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At least 145 records · Page 8

A review of predictive nonlinear theories for multiscale modeling of heterogeneous materials

Since the beginning of the industrial age, material performance and design have been in the midst of innovation of many disruptive technologies. Today's electronics, space, medical, transportation, and other industries are enriched by development, design and deployment of composite, heterogeneous and multifunctional materials. As a result, materials innovation is now considerably outpaced by other aspects from component design to product cycle. In this article, we review predictive nonlinear theories for multiscale modeling of heterogeneous materials. Deeper attention is given to multiscale modeling in space and to computational homogenization in addressing challenging materials science questions. Moreover, we discuss a state-of-the-art platform in predictive image-based, multiscale modeling with co-designed simulations and experiments that executes on the world's largest supercomputers. Such a modeling framework consists of experimental tools, computational methods, and digital data strategies. Once fully completed, this collaborative and interdisciplinary framework can be the basis of Virtual Materials Testing standards and aids in the development of new material formulations. Moreover, it will decrease the time to market of innovative products.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Prospects for in vivo estimation of photon linear attenuation coefficients using postprocessing dual-energy CT imaging on a commercial scanner: Comparison of analytic and polyenergetic statistical reconstruction algorithms

Purpose: Accurate patient-specific photon cross-section information is needed to support more accurate model-based dose calculation for low energy photon-emitting modalities in medicine such as brachytherapy and kilovoltage x-ray imaging procedures. A postprocessing dual-energy CT (pDECT) technique for noninvasivein vivo estimation of photon linear attenuation coefficients has been experimentally implemented on a commercial CT scanner and its accuracy assessed in idealized phantom geometries. Methods: Eight test materials of known composition and density were used to compare pDECT-estimated linear attenuation coefficients to NIST reference values over an energy range from 10 keV to 1 MeV. As statistical image reconstruction (SIR) has been shown to reconstruct images with less random and systematic error than conventional filtered backprojection (FBP), the pDECT technique was implemented with both an in-house polyenergetic SIR algorithm, alternating minimization (AM), as well as a conventional FBP reconstruction algorithm. Improvement from increased spectral separation was also investigated by filtering the high-energy beam with an additional 0.5 mm of tin. The law of propagated uncertainty was employed to assess the sensitivity of the pDECT process to errors in reconstructed images. Results: Mean pDECT-estimated linear attenuation coefficients for the eight test materials agreed within 1% of NIST reference values for energies from 1 MeV down to 30 keV, with mean errors rising to between 3% and 6% at 10 keV, indicating that the method is unbiased when measurement and calibration phantom geometries are matched. Reconstruction with FBP and AM algorithms conferred similar mean pDECT accuracy. However, single-voxel pDECT estimates reconstructed on a 1 × 1 × 3 mm{sup 3} grid are shown to be highly sensitive to reconstructed image uncertainty; in some cases pDECT attenuation coefficient estimates exhibited standard deviations on the order of 20% around the mean. Reconstruction with the statistical AM algorithm led to standard deviations roughly 40% to 60% less than FBP reconstruction. Additional tin filtration of the high energy beam exhibits similar pDECT estimation accuracy as the unfiltered beam, even when scanning with only 25% of the dose. Using the law of propagated uncertainty, low Z materials are found to be more sensitive to image reconstruction errors than high Z materials. Furthermore, it is estimated that reconstructed CT image uncertainty must be limited to less than 0.25% to achieve a target linear-attenuation coefficient estimation uncertainty of 3% at 28 keV. Conclusions: That pDECT supports mean linear attenuation coefficient measurement accuracies of 1% of reference values for energies greater than 30 keV is encouraging. However, the sensitivity of the pDECT measurements to noise and systematic errors in reconstructed CT images warrants further investigation in more complex phantom geometries. The investigated statistical reconstruction algorithm, AM, reduced random measurement uncertainty relative to FBP owing to improved noise performance. These early results also support efforts to increase DE spectral separation, which can further reduce the pDECT sensitivity to measurement uncertainty.

61 RADIATION PROTECTION AND DOSIMETRY↗

Addendum to the Corrective Action Decision Document/Closure Report for Corrective Action Unit 529: Area 25 Contaminated Materials, Nevada Test Site, Nevada (Rev. 1)

This document constitutes an addendum to the Corrective Action Decision Document/Closure Report for Corrective Action Unit 529: Area 25 Contaminated Materials, Nevada Test Site, Nevada as described in the document Recommendations and Justifications To Remove Use Restrictions Established under the U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office Federal Facility Agreement and Consent Order dated September 2013. The Use Restriction (UR) Removal document was approved by the Nevada Division of Environmental Protection on October 16, 2013. The approval of the UR Removal document constituted approval of each of the recommended UR removals. In conformance with the UR Removal document, this addendum consists of: This page that refers the reader to the UR Removal document for additional information The cover, title, and signature pages of the UR Removal document The NDEP approval letter The corresponding section of the UR Removal document This addendum provides the documentation justifying the cancellation of the UR for CAS 25-23-17, Contaminated Wash (Parcel H). This UR was established as part of FFACO corrective actions and was based on the presence of total petroleum hydrocarbon diesel-range organics contamination at concentrations greater than the NDEP action level at the time of the initial investigation.

54 ENVIRONMENTAL SCIENCES↗

Review Paper: Review of Instrumentation for Irradiation Testing of Nuclear Fuels and Materials

Over 50 years of nuclear fuels and materials irradiation testing has led to many countries developing significant improvements in instrumentation to monitor physical parameters and to control the test conditions in material test reactors (MTRs). Recently, there is increased interest to irradiate new materials and reactor fuels for advanced pressurized water reactors and Gen-IV reactor systems, such as sodium-cooled fast reactors, very high temperature reactors, supercritical water-cooled reactors, and gas-cooled fast reactors. This review paper documents the current state of instrumentation technologies in MTRs in the world and summarizes ongoing research efforts to deploy new sensors. As described in this paper, a wide range of sensors is available to measure key parameters of interest during fuels and materials irradiations in MTRs. Ongoing development efforts focus on providing MTR users a wider range of parameter measurements with smaller, higher accuracy sensors.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Evaluating Non-Fluoropolymer-Based Co-Extruded Backsheets Using Combined-Accelerated Stress Testing and Materials Forensics

Co-extruded, non-fluoropolymer backsheet films for photovoltaic (PV) modules have gained popularity in recent years based on their cost competitiveness. However, their viability has been thrown into question as a result of widespread, early-life field-failures of some materials, particularly the polyamide (PA)-based “AAA” backsheet product. Failure to detect weaknesses in those earlier products could be due, in part, to insufficient quality testing practices. New testing protocols have recently been developed to better evaluate such materials. Here we show the testing results for a non-fluoropolymer, co-extruded PA-based backsheet film, which demonstrates greater durability than AAA and some commercial fluoropolymers. Using material characterization techniques including Fourier-transform infrared spectroscopy (FTIR), wide-angle x-ray scattering (WAXS), differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy (XPS), elongation-to-break (ETB), and optical microscopy we perform a comprehensive failure analysis to better understand the materials weaknesses. This analysis can ultimately inform how best to improve the material and extend its lifetime. This work serves as a demonstration that some materials should not be discounted due to a single poorly designed product and that more appropriate qualification testing with subsequent materials analysis can be used to develop better materials.

41 EE - Solar Energy Technologies Office (EE-4S)↗

Impact of corrosion test container material in molten fluorides

The effects of crucible material choice on alloy corrosion rates in immersion tests in molten LiF–NaF–KF (46.5–11.5-42 mol. %) salt held at 850 °C for 500 hrs are described. Four crucible materials were studied. Molten salt exposures of Incoloy-800H in graphite, Ni, Incoloy-800H, and pyrolytic boron nitride (PyBN) crucibles all led to weight-loss in the Incoloy-800H coupons. Alloy weight loss was ~30 times higher in the graphite and Ni crucibles in comparison to the Incoloy-800H and PyBN crucibles. It is hypothesized galvanic coupling between the alloy coupons and crucible materials contributed to the higher corrosion rates. Alloy salt immersion in graphite and Ni crucibles had similar weight-loss hypothesized to occur due to the rate limiting out diffusion of Cr in the alloys to the surface where it reacts with and dissolves into the molten salt, followed by the reduction of Cr from solution at the molten salt and graphite/Ni interfaces. As a result, both the graphite and the Ni crucibles provided sinks for the Cr, in the formation of a Ni–Cr alloy in the case of the Ni crucible, and Cr carbide in the case of the graphite crucible.

14 SOLAR ENERGY↗

Elucidating the Impact of Flow on Material-Sensitive Critical Heat Flux and Boiling Heat Transfer Coefficients: An Experimental Study with Various Materials

In this work, steady-state internal flow boiling critical heat flux (CHF) experiments were carried out at 10°C inlet subcooling and atmospheric pressure (84 kPa at an altitude of about 5300 feet) with mass flux ranging from 200 to 2,000 kg/m 2 -s on seven tube materials, including the accident-tolerant fuel cladding candidate FeCrAl (C26M) alloy. At a relatively low flow rate, the sensitivity of CHF to different materials was appreciable (the average difference among the tested materials was 19% at 200 kg/m 2 -s). As the absolute CHF differences stayed constant for higher flow rates, the increased flow rate led to reduced relative CHF differences among the tested materials (average relative difference of 15% at 1,000 kg/m 2 -s). FeCrAl alloy claddings that were oxidized under simulated Light Water Reactor (LWR) conditions yielded CHF comparable to as-received FeCrAl alloy cladding, with less than 1.8% difference. Experimental CHF results imply marginal material sensitivity impacts on the departure from nucleate boiling ratio in steady-state nuclear reactor cores. Yet, for accident progression analysis, material sensitivity may hold importance, as boiling behavior variation at low mass flux is appreciable. Macroscopic material parameters (surface wettability, surface roughness, and thermal properties) do not provide a suitable explanation for observed material-sensitive CHFs. Yet, surface roughness and thermal effusivity revealed power and linear relations, respectively, to the nucleate boiling heat transfer coefficients at low mass flux. At high mass flux, material sensitivity on nucleate boiling heat transfer significantly decreased due to the increased shear stress on boiling surface overwhelming material-related boiling implications.

36 MATERIALS SCIENCE↗

Report on the FY18 Uniaxial Material Model Testing and Key Feature Test Articles Testing of Grade 91

This report summarizes the results from experiments performed in FY18 on Gr. 91 steel (heat 30176). The testing of Gr. 91 has technical significance because, currently, it is the only approved material for Class A construction in ASME Section III Division 5 that is strongly cyclic softening. The focus of this investigation is the effect of pre-cyclic loading history on the responses of Gr. 91 under key feature testing with Simplified Model Test (SMT) creep fatigue and two-bar thermal ratchet loading. For the pre-softened SMT, the SMT life reduction ratio was found to be approximately the same as the pre-softening fatigue damage ratio. The pre-softening also affected the ratchet behavior for the SMT specimens. Under the same two-bar thermal ratchet test conditions, the pre-softened specimens showed faster ratchet ting rates or larger accumulated strains than those without pre-softening history. In addition, results from previous uniaxial mechanical tests in support of the viscoplastic material model development for Gr. 91 are summarized, and the new results from thermomechanical testing at high temperature range are reported.

36 MATERIALS SCIENCE↗

NEET Micro-Pocket Fission Detector. Final Project report

A collaboration between the Idaho National Laboratory (INL), the Kansas State University (KSU), and the French Alternative Energies and Atomic Energy Commission, Commissariat à l'Énergie Atomique et aux Energies Alternatives, (CEA), is funded by the Nuclear Energy Enabling Technologies (NEET) program to develop and test Micro-Pocket Fission Detectors (MPFDs), which are compact fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package. When deployed, these sensors will significantly advance flux detection capabilities for irradiation tests in US Material Test Reactors (MTRs). Ultimately, evaluations may lead to a more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, and high performance reactors, allowing several Department of Energy Office of Nuclear Energy (DOE-NE) programs to obtain higher accuracy/higher resolution data from irradiation tests of candidate new fuels and materials. Specifically, deployment of MPFDs will address several challenges faced in irradiations performed at MTRs: Current fission chamber technologies do not offer the ability to measure fast flux, thermal flux and temperature within a single compact probe; MPFDs offer this option. MPFD construction is very different than current fission chamber construction; the use of high temperature materials allow MPFDs to be specifically tailored to survive harsh conditions encountered in-core of high performance MTRs. The higher accuracy, high fidelity data available from the compact MPFD will significantly enhance efforts to validate new high-fidelity reactor physics codes and new multi-scale, multi-physics codes. MPFDs can be built with variable sensitivities to survive the lifetime of an experiment or fuel assembly in some MTRs, allowing for more efficient and cost effective power monitoring. The small size of the MPFDs allows multiple sensors to be deployed, offering the potential to accurately measure the flux and temperature profiles in the reactor. This report summarizes the status at the end of year two of this three year project. As documented in this report, all planned accomplishments for developing this unique new, compact, multipurpose sensor have been completed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Improvements in design and operation of bubblers in the Savannah river site defense waste processing facility melter - 15163

In order to accelerate the closing of High Level Waste (HLW) tanks at the Savannah River Site (SRS), it was necessary to process more waste throughout the SRS liquid waste facilities. Therefore the Defense Waste Processing Facility (DWPF) needed to increase its production rate of radioactive waste glass filled canisters. To attain the increased production rate, four bubblers were installed in the DWPF Melter in September 2010 to agitate the DWPF Melter glass pool. The four bubblers were designed to be installed in existing nozzles on the top-head of the DWPF Melter. After a few years of successful operation with the original design, several changes have been made to the bubblers. The main change allows for the lower end (inside melter) of the bubbler to be replaced while the top end (outside melter) of the bubbler can be reused. This minimizes cost and waste at the DWPF. Material testing of the Inconel 690 bubbler pipes of used lower bubblers has been performed. Based on the material testing and issue with the integrity of some lower bubbler pipes used in the melter, a protective sleeve at the melt line was also added. Other changes for operational improvement or cost savings have also been made. Overall, performance of the bubblers continues to be excellent as canister production records have been achieved at the DWPF due in large part to the use of bubblers. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

STANDARD REFERENCE MATERIAL CHARPY TESTING FROM HIGH FLUENCE SURVEILLANCE CAPSULE

The Palisades Nuclear Generating Station included in its original surveillance program a surveillance capsule, designated A-60. The capsule was removed from its surveillance position in early 1995 and has been resident in the spent fuel pool since that time. It was harvested to perform characterization of surveillance specimens in this capsule in 2023. This capsule was irradiated to a fluence of 1.96x1020 n/cm2 (E> 1MeV) that is equivalent for more than 150 effective full power years for the current US reactor pressure vessel (RPV) fleet. This capsule contained several materials, including Charpy specimens of standard reference material (SRM) from Heavy-Section Steel Technology (HSST) A533-B Plate 01. To perform Charpy testing of this highly irradiated material, the new Charpy specimen transfer system was designed and implemented on Charpy impact testing machine in the hot cell to accommodate remote testing of these specimens. This new transfer system includes integrated environmental chamber to cool or heat Charpy specimens to the desired temperature. Testing of this highly irradiated material revealed very large shift of Charpy transition temperature, 188oC.

Sokolov, Mikhail [ORNL] (ORCID:0000000256373346)↗

NEET Micro-Pocket Fission Detector - FY 2012 Status Report

A research program has been initiated by the NEET program for developing and testing compact miniature fission chambers capable of simultaneously measuring thermal neutron flux, fast neutron flux and temperature within a single package. When implemented, these sensors will significantly advance flux detection capabilities for irradiation tests in US Materials Test Reactors (MTRs). Ultimately, evaluations may lead to a more compact, more accurate, and longer lifetime flux sensor for critical mock-ups, high performance reactors and commercial nuclear power plants. Deployment of Micro-Pocket Fission Detectors (MPFDs) in US DOE-NE program irradiation tests will address several challenges: Current fission chamber technologies do not offer the ability to measure fast flux, thermal flux and temperature within a single compact probe, MPFDs offer this option. MPFD construction is very different then current fission chamber construction; the use of high temperature materials allow MPFDs to be specifically tailored to survive harsh conditions in typical high performance MTR irradiation tests.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Improved precision and accuracy in quantifying plutonium isotope ratios by RIMS

Resonance ionization mass spectrometry (RIMS) holds the promise of rapid, isobar-free quantification of actinide isotope ratios in as-received materials (i.e. not chemically purified). Recent progress in achieving this potential using two Pu test materials is presented. RIMS measurements were conducted multiple times over a period of two months on two different Pu solutions deposited on metal surfaces. Measurements were bracketed with a Pu isotopic standard, and yielded absolute accuracies of the measured Pu-240/Pu-239 ratios of 0.7 and 0.58 %, with precisions (95 % confidence intervals) of 1.49 and 0.91 %. The minor isotope Pu-238 was also quantified despite the presence of a significant quantity of U-238 in the samples.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Springback Analysis of Draw-Bending of 980 MPa Cold Rolled Steel Sheet and Its Experimental Validation

Draw-bending experiment is carried out using a 1.2 mm-thick high strength steel sheet with a tensile strength of 980 MPa and the residual curvature of the draw-bent specimens are precisely measured. The die profile of the draw-bending testing machine rotates, so that the effect of friction force on the curvature data after springback can be neglected. Moreover, in order to quantitatively evaluate the Bauschinger effect of the test material, stress reversal tests are performed using an in-plane stress reversal testing machine. Furthermore, the finite element analyses (FEA) of the draw-bending experiment are carried out. The effect of the work hardening models (isotropic or combined), element types (shell or solid), and the number of integration points in the through-thickness direction on the amount of springback (residual curvature) are investigated in detail.

36 MATERIALS SCIENCE↗

Report on Project performance under the CRADA No PNNL/254, PLA 1, between BATTELLE as operator of Pacific Northwest National Laboratory under its U.S. Department of Energy Contract No. DE-AC05-76RL0 1830 and Isonics Corporation, Chairman and CEO: Christopher M. Toffales

Unattended decontamination of bio agents in enclosed environments. The goal of the project is the development of unattended method for environmentally safe, highly effective volumetric decontamination that kills on a contact multiple bio-agents including airborne and surface-adsorbed pathogens of different nature in enclosed environments with complex geometry like various buildings and transportation units as aircraft and ships The method employs two elements, proprietary Vortical Aerosol Generator (VAG) and Electrochemically Activated Solutions (EAS). The prototype of the method was developed under CRADA No PNNL/254, and was shown highly effective for irreversible decontamination of vegetative microbial cells, spores and viruses in a test chamber of ~100 ft 3 and in a room of ~3000 ft 3 . The electrochemical activation technology is based on the production of meta-stable (activated) solutions with anomalous physicochemical and catalytic reactivity for their further use in various technological processes in place of traditionally applied aggressive chemicals. Usual source for electrochemical activation processes is sodium chloride aqueous solution with the concentration of 1.0 g/L. EAS bactericidal effectiveness was previously demonstrated for different applications however, in all previous applications EAS was only used as a liquid agent. Present Method suggests an application of EAS as micro-aerosol (particle size in the range of 0.5-10 mµ), which behaves like a gas and eventually fills entire enclosed environment including hardly, not otherwise accessible sites. The term micro-aerosol of EAS (MAEAS) herein refers to an air-suspended EAS having micro-particle droplets of characteristic cross section and/or size comprising electrochemically-active agents with sufficiently large surface areas whereby the probability of a contact with bio agents in a process area is extremely high. EAS is produced with a commercially available STEL device (FEM-3 flow electrochemical module element; US Pat 5,635,040). Pneumatic Vortical Aerosol Generator (VAG) produces MAEAS. VAG is an original high output atomizer allowing for the production of the aerosol particles with the size in the range of 0.5 to 12 µm at the rate from 5 to 300 ml/min correspondingly, allowing a control of a required particle size. MAEAS has significant advantages over EAS, allowing for simultaneous decontamination of airborne and surface-adsorbed bio agents with minimal volume of atomized EAS and with essentially no waste. Experimental data indicate that MAEAS has very low corrosiveness, possess no negative effect to sensitive equipment and does not destroy the surface of different tested materials. Limited toxicity tests were conducted with mice directly exposed to EAS aerosol; no acute and short-term toxicity was identified.

bioagents↗