scholarly journals Overview of the Tolerance Limit Calculations with Application to TSURFER

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7092
Author(s):  
Hany Abdel-Khalik ◽  
Dongli Huang ◽  
Ugur Mertyurek ◽  
William Marshall ◽  
William Wieselquist
Keyword(s):  
New Technologies ◽  
National Laboratory ◽  
Integrated Approach ◽  
Tolerance Limit ◽  
Nuclear Industry ◽  
Mathematical Methods ◽  
Tolerance Limits ◽  
Regulatory Requirement ◽  
Oak Ridge ◽  
Wide Range

To establish confidence in the results of computerized physics models, a key regulatory requirement is to develop a scientifically defendable process. The methods employed for confidence, characterization, and consolidation, or C3, are statistically involved and are often accessible only to avid statisticians. This manuscript serves as a pedagogical presentation of the C3 process to all stakeholders—including researchers, industrial practitioners, and regulators—to impart an intuitive understanding of the key concepts and mathematical methods entailed by C3. The primary focus is on calculation of tolerance limits, which is the overall goal of the C3 process. Tolerance limits encode the confidence in the calculation results as communicated to the regulator. Understanding the C3 process is especially critical today, as the nuclear industry is considering more innovative ways to assess new technologies, including new reactor and fuel concepts, via an integrated approach that optimally combines modeling and simulation and minimal targeted validation experiments. This manuscript employs intuitive, analytical, numerical, and visual representations to explain how tolerance limits may be calculated for a wide range of configurations, and it also describes how their values may be interpreted. Various verification tests have been developed to test the calculated tolerance limits and to help delineate their values. The manuscript demonstrates the calculation of tolerance limits for TSURFER, a computer code developed by the Oak Ridge National Laboratory for criticality safety applications. The goal is to evaluate the tolerance limit for TSURFER-determined criticality biases to support the determination of upper, subcritical limits for regulatory purposes.

Review of Proposed Methodology for Risk-Informed Relaxation to ASME Section XI: Appendix G

2010 ◽  
Author(s):  
Terry Dickson ◽  
Eric Focht ◽  
Mark Kirk
Keyword(s):  
Structural Integrity ◽  
National Laboratory ◽  
The United States ◽  
Pressure Vessels ◽  
Reactor Vessel ◽  
Nuclear Industry ◽  
Oak Ridge ◽  
Wide Range ◽  
Asme Code ◽  
Reactor Pressure

The current regulations, as set forth by the United States Nuclear Regulatory Commission (NRC), to insure that light-water nuclear reactor pressure vessels (RPVs) maintain their structural integrity when subjected to planned normal reactor startup (heat-up) and shut-down (cool-down) transients are specified in Appendix G to 10 CFR Part 50, which incorporates by reference Appendix G to Section XI of the American Society of Mechanical Engineers (ASME) Code. The technical basis for these regulations are now recognized by the technical community as being conservative and some plants are finding it increasingly difficult to comply with the current regulations. Consequently, the nuclear industry has developed, and submitted to the ASME Code for approval, an alternative risk-informed methodology that reduces the conservatism and is consistent with the methods previously used to develop a risk-informed revision to the regulations for accidental transients such as pressurized thermal shock (PTS). The objective of the alternative methodology is to provide a relaxation to the current regulations which will provide more operational flexibility, particularly for reactor pressure vessels with relatively high irradiation levels and radiation sensitive materials, while continuing to provide reasonable assurance of adequate protection to public health and safety. The NRC and its contractor at Oak Ridge National Laboratory (ORNL) have recently performed an independent review of the industry proposed methodology. The NRC / ORNL review consisted of performing probabilistic fracture mechanics (PFM) analyses for a matrix of cool-down and heat-up rates, permutated over various reactor geometries and characteristics, each at multiple levels of embrittlement, including 60 effective full power years (EFPY) and beyond, for various postulated flaw characterizations. The objective of this review is to quantify the risk of a reactor vessel experiencing non-ductile fracture, and possible subsequent failure, over a wide range of normal transient conditions, when the maximum allowable thermal-hydraulic boundary conditions, derived from both the current ASME code and the industry proposed methodology, are imposed on the inner surface of the reactor vessel. This paper discusses the results of the NRC/ORNL review of the industry proposal including the matrices of PFM analyses, results, insights, and conclusions derived from these analyses.

scholarly journals Octane Index Applicability over the Pressure-Temperature Domain

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Tommy R. Powell ◽  
James P. Szybist ◽  
Flavio Dal Forno Chuahy ◽  
Scott J. Curran ◽  
John Mengwasser ◽  
...  
Keyword(s):  
High Efficiency ◽  
National Laboratory ◽  
Operating Conditions ◽  
Dominant Factor ◽  
Compression Ignition ◽  
Oak Ridge ◽  
Operating Modes ◽  
Wide Range ◽  
Thermodynamic Conditions ◽  
Si Engines

Modern boosted spark-ignition (SI) engines and emerging advanced compression ignition (ACI) engines operate under conditions that deviate substantially from the conditions of conventional autoignition metrics, namely the research and motor octane numbers (RON and MON). The octane index (OI) is an emerging autoignition metric based on RON and MON which was developed to better describe fuel knock resistance over a broader range of engine conditions. Prior research at Oak Ridge National Laboratory (ORNL) identified that OI performs reasonably well under stoichiometric boosted conditions, but inconsistencies exist in the ability of OI to predict autoignition behavior under ACI strategies. Instead, the autoignition behavior under ACI operation was found to correlate more closely to fuel composition, suggesting fuel chemistry differences that are insensitive to the conditions of the RON and MON tests may become the dominant factor under these high efficiency operating conditions. This investigation builds on earlier work to study autoignition behavior over six pressure-temperature (PT) trajectories that correspond to a wide range of operating conditions, including boosted SI operation, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). A total of 12 different fuels were investigated, including the Co-Optima core fuels and five fuels that represent refinery-relevant blending streams. It was found that, for the ACI operating modes investigated here, the low temperature reactions dominate reactivity, similar to boosted SI operating conditions because their PT trajectories lay close to the RON trajectory. Additionally, the OI metric was found to adequately predict autoignition resistance over the PT domain, for the ACI conditions investigated here, and for fuels from different chemical families. This finding is in contrast with the prior study using a different type of ACI operation with different thermodynamic conditions, specifically a significantly higher temperature at the start of compression, illustrating that fuel response depends highly on the ACI strategy being used.

scholarly journals Shared Research Equipment at OAK Ridge National Laboratory

1998 ◽  
Vol 4 (S2) ◽  
pp. 470-471
Author(s):  
N. D. Evans ◽  
E. A. Kenik ◽  
M. K. Miller
Keyword(s):  
Semiconductor Device ◽  
National Laboratory ◽  
Atomic Scale ◽  
Fiscal Year ◽  
Probe Field ◽  
Oak Ridge ◽  
Wide Range ◽  
Oak Ridge National Laboratory ◽  
Electron Microscopes ◽  
Research Equipment

The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory (ORNL) provides microanalytical facilities for studies within the materials sciences. Available instrumentation includes advanced analytical electron microscopes, atom probe field ion microscopes, and nanoindentation facilities. Through SHaRE, researchers from U.S. universities, industries, and government laboratories may collaborate with Facility scientists to perform research not possible at their home institutions. International collaborations are also possible. Most SHaRE projects seek correlations at the microscopic or atomic scale between structure and properties in a wide range of metallic, ceramic, and other structural materials. Typical research projects include studies of magnetic materials, advanced alloys, catalysts, semiconductor device materials, high Tc superconductors, and surface-modified polymers. Projects usually involve one or more external researchers visiting the SHaRE Facility for up to three weeks during the fiscal year (October 1 - September 30). Project approval is based upon the scientific excellence and relevance of proposed collaborative research.

Production function for short-rotation woody-crop Populus spp. plantations

1994 ◽  
Vol 24 (1) ◽  
pp. 180-184 ◽  
Author(s):  
David A. Lortz ◽  
David R. Betters ◽  
Lynn L. Wright
Keyword(s):  
Production Function ◽  
Cultural Practices ◽  
National Laboratory ◽  
Development Program ◽  
The United States ◽  
Oak Ridge ◽  
Short Rotation ◽  
Wide Range ◽  
Woody Crop ◽  
Populus Spp

Short-rotation woody-crop Populus spp. plantations have the potential to produce large amounts of biomass in short time periods, typically 4–8 years. A production function equation is shown to predict yields for such plantations. The equation is based, in part, on information from biomass production experiments conducted across the United States. These experimental plots are sponsored by the Biofuels Feedstock Development Program of Oak Ridge National Laboratory. The equation uses nine parameters including both cultural practices and climatic and soil site conditions as independent variables. The equation (R2 = 0.86) is accurate and applicable to a wide range of conditions.

scholarly journals Avaliação ocupacional quantitativa das temperaturas extremas em um laboratório acadêmico: os reflexos da exposição para a saúde dos trabalhadores

2019 ◽  
Vol 1 (44) ◽  
pp. 79
Author(s):  
Mayslane De Sousa Gomes ◽  
Brígida Monteiro Gualberto Montenegro ◽  
Daliane De Almeida Alves ◽  
Renata Paiva Da Nóbrega Costa
Keyword(s):  
Heat Exposure ◽  
Measurement Instrument ◽  
Education Institution ◽  
Tolerance Limit ◽  
Extreme Temperatures ◽  
Tolerance Limits ◽  
Environmental Evaluation ◽  
A Value ◽  
Wide Range ◽  
Environmental Agents

<p>Every day occupational diseases incapacitate thousands of workers in a wide range of activities causing problems which vary from temporary retirements until death The diseases usually start when there is exposure to physical environmental agents above tolerance limits such as: extreme temperatures (cold and heat) present in food laboratories. In this context, this study aimed to analyze the occupational exposure to extreme temperatures in an academic milk processing laboratory of a Public Education Institution. The methodology used a descriptive, quantitative approach. Data collection used the environmental measurement instrument A recommended Thermal Stress Measure for evaluation of heat exposure Humidity Bulb Index – Globe Thermometer (IBUTG), based on the Tolerance Limits proposed by NR 15 and environmental evaluation of the cold through the ACGIH Tolerance Limit Table. The result obtained for the evaluation of the heat was of an average IBUTG of 30.075 for yoghurt production, below the tolerance limit proposed by NR 15. In order to evaluate the cold, a value of 8 ºC was obtained and the temperature range could be considered acceptable by the ACGIH for a 1 hour and 40 minutes intercalated journey.</p>

Creep Strength and Microstructure of AL20-25+Nb Alloy Sheets and Foils for Advanced Microturbine Recuperators

2006 ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Neal D. Evans ◽  
Yukinori Yamamoto ◽  
Karren L. More ◽  
...  
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Creep Resistance ◽  
National Laboratory ◽  
Rupture Life ◽  
Cost Effective ◽  
Test Facility ◽  
Oak Ridge ◽  
Collaborative Program ◽  
Wide Range

The Oak Ridge National Laboratory (ORNL) and ATI Allegheny-Ludlum began a collaborative program in 2004 to produce a wide range of commercial sheets and foils of the new AL20-25+Nb stainless alloy, specifically designed for advanced microturbine recuperator applications. There is a need for cost-effective sheets/foils with more performance and reliability at 650–750°C than 347 stainless steel, particularly for larger 200–250 kW microturbines. Phase I of this collaborative program produced the sheets and foils needed for manufacturing brazed plated-fin (BPF) aircells, while Phase II provided foils for primary surface (PS) aircells, and modified processing to change the microstructure of sheets and foils for improved creep-resistance. Phase I sheets and foils of AL20-25+Nb have much more creep-resistance than 347 steel at 700–750°C, and foils are slightly stronger than HR120 and HR230. Preliminary results for Phase II show nearly double the creep-rupture life of sheets at 750°C/100 MPa, with the first foils tested approaching the creep resistance of alloy 625 foils. AL20-25+Nb alloy foils are also now being tested in the ORNL Recuperator Test Facility.

Z-Contrast Imaging of Grain Boundaries in Semiconductors

1996 ◽  
Vol 54 ◽  
pp. 332-333
Author(s):  
M. F. Chisholm ◽  
S. J. Pennycook
Keyword(s):  
Grain Boundaries ◽  
Chemical Potential ◽  
National Laboratory ◽  
Atomic Scale ◽  
Structural Defects ◽  
Specimen Thickness ◽  
Contrast Imaging ◽  
Oak Ridge ◽  
Wide Range ◽  
Annular Detector

Interest in grain boundaries in semiconductors is linked to the application of polycrystalline semiconductors as photovoltaic and interconnect materials. In real devices such as solar cells and MOS structures as well as future devices such as flat-panel displays, the intergranular regions of the polycrystalline solid have a significant effect on the flow of electronic current. These grain boundary barriers exist because the chemical potential of the boundary atoms are shifted from the bulk value by the change in local symmetry. The chemical potential is also changed by impurities, other structural defects, and other phases in the boundary. The lack of knowledge on the atomic structure of grain boundaries is, at present, the greatest barrier to advancements in the understanding of the electrical properties of these defects.The advances of the last few years have provided the tools with which to probe these interfaces at the true atomic scale. One such tool is the high-resolution scanning transmission electron microscope installed at Oak Ridge National Laboratory (VG Microscopes HB603) that can form a 1.27Å electron probe. Images are formed by scanning the probe across a thin sample and using an annular detector to collect electrons scattered to high angles. Because the annular detector collects electrons scattered over a wide range of angles, phase correlations and dynamical diffraction effects are averaged by this annular integration. Thus, an image with incoherent characteristics is produced and retained to relatively large specimen thickness.

scholarly journals Neutrons and supercomputing for Complex Biological Systems

2014 ◽  
Vol 70 (a1) ◽  
pp. C17-C17
Author(s):  
Paul Langan
Keyword(s):  
Neutron Beam ◽  
High Performance ◽  
National Laboratory ◽  
Integrated Approach ◽  
Biological Research ◽  
Deuterium Labeling ◽  
Oak Ridge ◽  
Technological Advances ◽  
Experimental Approaches ◽  
Predictive Understanding

Frontier challenges in biological research increasingly require gaining a predictive understanding of complex dynamic and flexible multi-component systems. Gaining that understanding can come from combining several experimental approaches to inform multi-scale computer models and simulations. Complementary experimental approaches used include electron microscopy, mass spectrometry, X-ray scattering, and NMR, but outstanding challenges remain. Neutron scattering has great potential to address the remaining challenges by providing elusive information that cannot be obtained otherwise. Researchers are now gaining access to new instrumentation on intense neutron beam lines at the Spallation Neutron Source (SNS) and the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). An unprecedented opportunity exists that we are exploiting by developing and broadening the use of neutrons in biological research by leveraging deuterium labeling and high performance computing. In order to develop this innovative integrated approach, and to take full advantage of the increase in availability and capability of neutron beam lines, further technological advances are required. In this talk I will present an overview of neutron facilities at ORNL, and give examples of their growing application in biological research. I will then discuss how the future challenges in biology are driving further technological developments that will lead to new understanding in the emerging areas of dynamic functional assemblies, disorder and flexibility, biological membranes and associated complexes, and biomolecular function and ligand binding. Neutrons can provide unique information that will transform these areas of research, opening up new lines of biological inquiry.

3-D Modeling of Forced-Flow Thermal-Gradient CVI for Ceramic Composite Fabrication

1989 ◽  
Vol 168 ◽  
Author(s):  
Thomas L. Starr ◽  
Arlynn W. Smith
Keyword(s):  
Thermal Gradient ◽  
National Laboratory ◽  
Ceramic Composites ◽  
Chemical Vapor Infiltration ◽  
Forced Flow ◽  
Process Conditions ◽  
Uniform Density ◽  
Oak Ridge ◽  
Matrix Deposition ◽  
Wide Range

AbstractForced-flow thermal-gradient chemical vapor infiltration (FCVI) has demonstrated excellent potential for fabrication of high strength, high toughness ceramic composites. Extension of this process to large and complex shapes is facilitated by use of a computer model to optimize process conditions and hardware for rapid, uniform infiltration.A 3-D model has been developed using a “finite volume” formulation. A steady-state solution for heat conduction and Darcy's law permeation produces temperature and gas flow distributions within the fiber preform. These are used to generated matrix deposition rates within each volume element. By “marching” through time, a complete simulation of the densification process can be obtained.The model is demonstrated for a FCVI system with cylindrical symmetry and compared to experimental results obtained at the Oak Ridge National Laboratory. The model results suggest a self-optimizing feature of the force flow/thermal gradient CVI process that produces uniform density in the final composite over a range of infiltration conditions. This matches experimental observation where good uniformity has been achieved over a wide range of gas flows, pressure and temperature.

Developing New Cast Austenitic Stainless Steels With Improved High-Temperature Creep Resistance

2007 ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Neal D. Evans ◽  
Michael J. Pollard
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Creep Strength ◽  
Stainless Steels ◽  
Creep Resistance ◽  
National Laboratory ◽  
Austenitic Stainless Steels ◽  
Alloy Development ◽  
Oak Ridge ◽  
Wide Range

Oak Ridge National Laboratory (ORNL) and Caterpillar have recently developed a new cast austenitic stainless steel, CF8C-Plus, for a wide range of high-temperature applications, including diesel exhaust components and turbine casings. The creep-rupture life of the new CF8C-Plus is over ten times greater than that of the standard cast CF8C stainless steel, and the creep-strength is about double. Another variant, CF8C-Plus Cu/W has been developed with even more creep strength at 750–850°C. The creep-strength of these new cast austenitic stainless steels is close to that of Ni-based superalloys like 617. CF8C-Plus steel was developed in about 1.5 years using an “engineered microstructure” alloy development approach, which produces creep resistance based on formation of stable nano-carbides (NbC) and prevention of deleterious intermetallics (sigma, Laves). CF8C-Plus steel won a 2003 R&D 100 Award, and to date, over 32,000 lb have been produced in various commercial component trials. The current commercialization status of the alloy is summarized.

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