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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,783 records · Page 99
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Development of an advanced multi-scale subchannel model for CRUD risk assessments

AREVA NP has developed a process, based upon standard licensing methods and specialized applications, for the assessment of the risk of crud induced corrosion and crud induced axial off-set. This streamlined process allows for the evaluation of the crud risk for full core subchannel by subchannel models, by applying local conditions on each fuel rod/subchannel, with axial nodes spanning several centimeters. AREVA NP has applied these tools successfully to units from various NSSS vendors. To date, there have been no plant performance issues that have been outside the performance as predicted by the AREVA NP risk assessment tools. The study presented in this paper utilized the core simulator and thermal-hydraulic packages of this tool set to evaluate the effects of changing various fuel cycle design (e.g. radial zoning patterns) and fuel assembly design parameters (e.g. fuel rod diameter, spacer grid placement) on thermal-hydraulic key decision variables (KDVs) of interest. The study may be valuable as a first step towards optimizing the fuel cycle design, optimizing the fuel lattice design, or evaluating potential operating changes such as a power up-rate or modification of the cycle length for a given PWR plant. The various geometric inputs to the AREVA NP risk assessment process were tested by individually adjusting a single parameter and observing the effect. Multi-parameter studies are also included to assess the impact of optimized fuel cycle designs. The sensitivity of the model, in terms of thermal-hydraulic results, is presented. Provided a relationship between the thermal-hydraulic results to both crud deposition thickness and lithium uptake in the zirconium cladding oxide layer, approximate impacts to the risk of crud induced corrosion and crud induced axial off-set can be estimated. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

The Development of a Small-Scale Project Model for Waste Management at the Port Hope Conversion Facility - 19126

Cameco Corporation's (Cameco) Port Hope Conversion Facility (PHCF) was previously owned by the federal Crown Corporation, Eldorado Nuclear, which held a significant inventory of legacy waste material at the time Cameco was formed in 1988. Over time, Cameco's ongoing operations contributed to an increase in the volume of low-level radioactive waste managed onsite. Since 2011, Cameco has completed annual waste management campaigns with the goal of accelerating the recycle/disposal of accumulated legacy radioactive wastes stored at its Ontario operations. With disposal options for low-level radioactively contaminated wastes in Canada limited due to cost considerations and no commercially accessible landfills licensed for radioactive material. In recent years, Cameco has started to ship marginally contaminated wastes (<500 ppm uranium) to the United States for disposal in an appropriate landfill owned by US Ecology in Idaho. Numerous successful campaigns totaling over 1,000 successful shipments, have been completed to transport drummed and/or bagged material by rail in gondola cars to the disposal facility in Idaho since 2011. All shipments have been completed in compliance with all environmental regulations, with a perfect compliance record maintained to date. To achieve this excellent compliance record, the campaigns require careful planning by both organizations, as well as deployment of personnel from the Idaho facility during the campaign for project management, characterization and/or radiation monitoring support. As the accumulated waste inventory has been reduced through these projects, the scope and duration of each campaign has also decreased. In the last few years, road transport directly to the Idaho facility has also been utilized. This option allows for the deployment of small projects that may be completed for a smaller inventory of a specific waste type and to manage newly-generated low-level radioactive wastes on an ongoing basis. These projects have ranged from a single standard van shipment to multiple trucks running continuous loops between the Ontario and Idaho or Ontario and an intermediary site and have been utilized for marginally contaminated wastes (<500 ppm uranium) as well as marginally contaminated wastes with additional hazard classification. Cameco and US Ecology personnel have collaborated to develop characterization and shipment procedures that enable these projects to be executed in full compliance with all Canadian and US regulations, without deployment of personnel from the Idaho facility, while maintaining adequate oversight by both organizations to ensure that the waste is safely and compliantly managed. These protocols have been implemented and optimized for the Port Hope Conversion Facility and will be rolled out to other Cameco facilities in Ontario through 2019. Cameco expects to utilize the small project model for the long term to ensure that eligible marginally contaminated wastes (<500 ppm uranium) are managed appropriately to ensure that once the legacy material is eliminated, it remains so. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Multiscale Modeling of the Mechanical Response of Silicon Carbide Composite Within the Accelerated Fuel Qualification Framework

The accelerated fuel qualification (AFQ) framework has been used for the initial development of multiscale modeling of silicon carbide (SiC) fiber reinforced composite (SiC-SiC). The AFQ framework provides a methodology to leverage physics-informed multiscale modeling along with a reduced set of empirical test data to reduce the time and cost of licensing and qualification of new nuclear fuel systems while maintaining the overall nuclear power plant safety case. SiC-SiC is being proposed for in-core applications, most notably fuel cladding, for current and next-generation nuclear reactors because of its high temperature stability, irradiation tolerance, and ability to withstand many accident conditions. As these composites exhibit multiscale architectures and complex microstructure-based fracture mechanics, it is an appealing use case for the AFQ methodology. While the end goal of this work is a single multiscale model that can be used for predictive in-core performance, current focus is on the individual various length scale models. Four individual models have been initially developed from microscale to engineering system level to capture key physics-based effects across different length scales. These models include a microscale homogenized tow model, a mesoscale fast Fourier transform–based weave model that integrates the homogenized tow model, a mesoscale finite element–based weave model, and a system-level BISON fuel performance model. Results of these models have undergone an initial comparison with separate-effects test data showing a good match to experimental results. By using the AFQ framework during model development, several near-term benefits have been secured including a reduction in development time for the SiC-SiC cladding, more targeted irradiation testing, and a better understanding of uncertainty.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Advanced Turbulence Models for Large-Scale Atmospheric Boundary Layer Flows

We present high-fidelity large-eddy-simulation (LES) modeling approaches for the turbulent atmospheric boundary layer (ABL) flows. Wind energy is a prime example of an application driven by ABL. Generation of electrical energy from farms of wind turbines at night in the stable ABL is a particularly interesting situation. In this report, we consider the well-known GEWEX (Global Energy and Water Cycle Experiment) Atmospheric Boundary Layer Study (GABLS) stably stratified benchmark LES case. We use a high-order spectral element code Nek5000/RS, which is supported under the DOE's Exascale Computing Project (ECP) Center for Efficient Exascale Discretizations (CEED) project, targeting application simulations on various acceleration-device based exascale computing platforms. In our earlier ANL report, we demonstrated our newly developed subgrid-scale (SGS) models based on high-pass filter (HPF), mean-field eddy viscosity (MFEV), and Smagorinsky (SMG) with no-slip and traction boundary conditions, provided with low-order statistics, convergence and turbulent structure analysis. In this report, we extend the range of our SGS modeling approaches in the context of the mean-field eddy viscosity (MFEV), to include the solution of an SGS turbulent kinetic energy equation (TKE). We demonstrate the model fidelity of Nek5000/RS in comparison to that of AMR-Wind, a block-structured second-order finite-volume code with adaptive-mesh-refinement capabilities, with which we studied scaling performance for both codes in comparison on DOE's leadership computing platforms.

17 WIND ENERGY↗
NASA NTRS1992

Scale effects in the response and failure of fiber reinforced composite laminates loaded in tension and in flexure

The feasibility of using scale model testing for predicting the full-scale behavior of flat composite coupons loaded in tension and beam-columns loaded in flexure is examined. Classical laws of similitude are applied to fabricate and test replica model specimens to identify scaling effects in the load response, strength, and mode of failure. Experiments were performed on graphite-epoxy composite specimens having different laminate stacking sequences and a range of scaled sizes. From the experiments it was deduced that the elastic response of scaled composite specimens was independent of size. However, a significant scale effect in strength was observed. In addition, a transition in failure mode was observed among scaled specimens of certain laminate stacking sequences. A Weibull statistical model and a fracture mechanics based model were applied to predict the strength scale effect since standard failure criteria cannot account for the influence of absolute specimen size on strength.

Jackson, Karen E.↗
NASA NTRS2012

Evaluation of Icing Scaling on Swept NACA 0012 Airfoil Models

Icing scaling tests in the NASA Glenn Icing Research Tunnel (IRT) were performed on swept wing models using existing recommended scaling methods that were originally developed for straight wing. Some needed modifications on the stagnation-point local collection efficiency (i.e., beta(sub 0) calculation and the corresponding convective heat transfer coefficient for swept NACA 0012 airfoil models have been studied and reported in 2009, and the correlations will be used in the current study. The reference tests used a 91.4-cm chord, 152.4-cm span, adjustable sweep airfoil model of NACA 0012 profile at velocities of 100 and 150 knot and MVD of 44 and 93 mm. Scale-to-reference model size ratio was 1:2.4. All tests were conducted at 0deg angle of attack (AoA) and 45deg sweep angle. Ice shape comparison results were presented for stagnation-point freezing fractions in the range of 0.4 to 1.0. Preliminary results showed that good scaling was achieved for the conditions test by using the modified scaling methods developed for swept wing icing.

Tsao, Jen-Ching↗