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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 127 records · Page 7

Pacific Northwest National Laboratory Investigation of the Stress Corrosion Cracking in Nickel-Base Alloys (Volume 2)

The objective of this program is to evaluate the primary water stress corrosion cracking (PWSCC) susceptibility of high chromium alloy 690 and its weld metals, establish quantitative measurements of crack-growth rates and determine relationships among cracking susceptibility, environmental conditions and metallurgical characteristics. Stress-corrosion, crack-growth rates have been determined for 12 alloy 690 specimens, 11 alloy 152/52/52M weld metal specimens, 4 alloy 52M/182 overlay specimens and 2 alloy 52M/82 inlay specimens in simulated PWR primary water environments. The alloy 690 test materials included three different heats of extruded control-rod-drive mechanism (CRDM) tubing with variations in the initial material condition and degree of cold work for one heat. Two cold-rolled (CR) alloy 690 plate heats were also obtained and evaluated enabling comparisons to the CR CRDM materials. Weld metal, overlay and inlay specimens were machined from industry mock ups to provide plant-representative materials for testing. Specimens have been tested for one alloy 152 weld, two alloy 52 welds and three alloy 52M welds. The overlay and inlay specimens were prepared to propagate stress-corrosion cracks from the alloy 182 or 82 material into the more resistant alloy 52M. In all cases, crack extension was monitored in situ by direct current potential drop (DCPD) with length resolution of about +1 µm making it possible to measure extremely low growth rates approaching 5x10 -10 mm/s. Most SCC tests were performed at 325-360°C with hydrogen concentrations from 11-29 cc/kg; however, environmental conditions were modified during a few experiments to evaluate the influence of temperature, water chemistry or electrochemical potential on propagation rates. In addition, low-temperature (~50°C) cracking behavior was examined for selected alloy 690 and weld metal specimens. Extensive characterizations have been performed on material microstructures and stress-corrosion cracks by optical and electron microscopy techniques and linked to crack-growth test results to help define material and environmental parameters controlling SCC susceptibility.

Bruemmer, Stephen M.↗

Dissolution of Material and Test reactor Fuel in an H-Canyon Dissolver

In an amended record of decision for the management of spent nuclear fuel (SNF) at the Savannah River Site, the US Department of Energy has authorized the dissolution and recovery of U from 1000 bundles of Al-clad SNF. The SNF is fuel from domestic and foreign research reactors and is typically referred to as Material Test Reactor (MTR) fuel. Bundles of MTR fuel containing assemblies fabricated from U-Al alloys (or other U compounds) are currently dissolved using a Hg-catalyzed HNO3 flowsheet. Since the development of the existing flowsheet, improved experimental methods have been developed to more accurately characterize the offgas composition and generation rate during laboratory dissolutions. Recently, these new techniques were successfully used to develop a flowsheet for the dissolution of High Flux Isotope Reactor (HFIR) fuel. Using the data from the HFIR dissolution flowsheet development and necessary laboratory experiments, the Savannah River National Laboratory (SRNL) was requested to define flowsheet conditions for the dissolution of MTR fuels. With improved offgas characterization techniques, SRNL will be able define the number of bundles of fuel which can be charged to an H-Canyon dissolver with much less conservatism.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Laser-accelerated particle beams for stress testing of materials

Laser-driven particle acceleration, obtained by irradiation of a solid target using an ultra-intense (I > 10 18 W/cm 2 ) short-pulse (duration <1 ps) laser, is a growing field of interest, in particular for its manifold potential applications in different domains. Here, we provide experimental evidence that laser-generated particles, in particular protons, can be used for stress testing materials and are particularly suited for identifying materials to be used in harsh conditions. We show that these laser-generated protons can produce, in a very short time scale, a strong mechanical and thermal damage, that, given the short irradiation time, does not allow for recovery of the material. We confirm this by analyzing changes in the mechanical, optical, electrical, and morphological properties of five materials of interest to be used in harsh conditions.

Science & Technology - Other Topics↗

Poster for 12th World Conference for Neutron Radiography (WCNR-12)

Complimentary Relationships Between Neutron Computed Radiography and Digital X-ray Radiography of Radioactive Specimens The Transient Reactor Test (TREAT) Facility is a 19,000 MW reactor located at the Idaho National Laboratory which is used for transient testing of materials and experiments. A neutron radiography facility is installed which allows for low resolution neutron imaging with a capability of items up to 20 cm wide and 400 cm long. Along with the neutron radiography facility, a 370 kV digital X-ray system is located onsite for when X-ray imaging is more practical or when rapid imaging is requested. The X-ray facility can accommodate specimens up to 61 cm wide and 1000 cm long. This poster discusses the complimentary relationship between transfer-method Neutron Computed Radiography (nCR) and Digital X-ray Radiography (DR) imaging of radioactive specimens along with practical applications for nuclear fuels and materials testing programs. Both nCR and DR images were acquired of inert gas and water filled apparatus containing differing materials at varying radiation levels. Highly radioactive items have no effect on nCR image quality whereas radioactivity has varying degrees of effect in DR. Radioactive items as high as 20 mSv/h have been successfully imaged using X-ray DR methods.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Investigation of Laser Coupling for Impulse Generation

The goal of the proposed work is to develop new laser-target configurations such that with the appropriate laser irradiation parameters (intensity, pulse-shape, pulsewidth) and target design, the induced stress (shock) wave in test materials simulates that which would result from absorption of an intense x-ray pulse. We will develop new target configurations using added ‘laser coupling/tamping’ layer(s) to materials under test to increase and to tailor the laser induced impulse. The successful completion of the proposed research will develop new capabilities and techniques that will provide cost effective techniques to allow assessment of new aeroshell materials and aeroshell configurations for strategic applications and allow measurement of key material properties, thus providing basic data needed for detailed modeling and simulation that can be extrapolated to threat conditions.

36 MATERIALS SCIENCE↗

Controlled shear/tension fixture

A test fixture for simultaneously testing two material test samples is provided. The fixture provides substantially equal shear and tensile stresses in each test specimens. By gradually applying a load force to the fixture only one of the two specimens fractures. Upon fracture of the one specimen, the fixture and the load train lose contact and the second specimen is preserved in a state of upset just prior to fracture. Particular advantages of the fixture are (1) to control the tensile to shear load on the specimen for understanding the effect of these stresses on the deformation behavior of advanced materials, (2) to control the location of fracture for accessing localized material properties including the variation of the mechanical properties and residual stresses across the thickness of advanced materials, (3) to yield a fractured specimen for strength measurement and an unfractured specimen for examining the microstructure just prior to fracture.

36 MATERIALS SCIENCE↗

Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo-Controlled Tube Bulge Testing Apparatus

Biaxial stress tests of rolled pure titanium sheet (JIS 1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure titanium sheet was bent and welded to make tubular specimens. Combined tension-internal pressure was applied to the tubular specimens using the servo-controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101-117 (2002)], so that the strain rate ratio, {epsilon}{sub {phi}}:{epsilon}{theta}, in the axial ({phi}) and circumferential ({theta}) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.

36 MATERIALS SCIENCE↗

The National Criticality Experiments Research Center at the Device Assembly Facility, Nevada National Security Site: Status and Capabilities, Summary Report

The National Criticality Experiments Research Center (NCERC) was officially opened on August 29, 2011. Located within the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS), the NCERC has become a consolidation facility within the United States for critical configuration testing, particularly those involving highly enriched uranium (HEU). The DAF is a Department of Energy (DOE) owned facility that is operated by the National Nuclear Security Agency/Nevada Site Office (NNSA/NSO). User laboratories include the Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL). Personnel bring their home lab qualifications and procedures with them to the DAF, such that non-site specific training need not be repeated to conduct work at DAF. The NNSS Management and Operating contractor is National Security Technologies, LLC (NSTec) and the NNSS Safeguards and Security contractor is Wackenhut Services. The complete report provides an overview and status of the available laboratories and test bays at NCERC, available test materials and test support configurations, and test requirements and limitations for performing sub-critical and critical tests. The current summary provides a brief summary of the facility status and the method by which experiments may be introduced to NCERC.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Test Methods for Cementitious Seal Materials for Borehole Disposal - 17352

The Nuclear and Energy Research Institute (IPEN-CNEN/SP) in Sao Paulo-Brazil, is considering borehole disposal of disused sealed radioactive sources (DSRS), which were used in smoke detectors, lightning arresters, radiotherapy, industrial gauges, irradiators, and other applications. The current IPEN concept of borehole is a modified BOSS system developed by the International Atomic Energy Agency (IAEA). It differs from the IAEA's design in that the disposal zone is below 300 m, and the DSRS are placed directly in the disposal packages constituted of stainless steel containers with 1.5 L capacity. A borehole drilled through sediment and granite, stabilized with stainless steel casing and cement grout is proposed for the conceptual model. Standard cement-material test methods and performance specific test methods, including accelerated aging methods, are needed for modeling the performance of the candidate cementitious grouts. A cross-disciplinary team from the USA Savannah River National laboratory is providing technical assistance to IPEN in this performance assessment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

In Vitro Thrombogenicity Testing of Biomaterials in a Dynamic Flow Loop: Effects of Length and Quantity of Test Samples

Abstract The results of in vitro dynamic thrombogenicity testing of biomaterials and medical devices can be significantly impacted by test conditions. To develop and standardize a robust dynamic in vitro thrombogenicity tool, the key test parameters need to be appropriately evaluated and optimized. We used a flow loop test system previously developed in our laboratory to investigate the effects of sample length and the number of samples per test loop on the thrombogenicity results. Porcine blood heparinized to a donor-specific target concentration was recirculated at room temperature through polyvinyl chloride (PVC) tubing loops containing test materials for 1 h at 200 mL/min. Four test materials (polytetrafluoroethylene (PTFE), latex, PVC, and silicone) with various thrombotic potentials in two sample lengths (12 and 18 cm) were examined. For the 12-cm long materials, two different test configurations (one and two samples per loop) were compared. Thrombogenicity was assessed through percent thrombus surface coverage, thrombus weight, and platelet count reduction in the blood. The test system was able to effectively differentiate the thrombogenicity profile of the materials (latex > silicone > PVC ≥ PTFE) at all test configurations. Increasing test sample length by 50% did not significantly impact the test results as both 12 and 18 cm sample lengths were shown to equally differentiate thrombotic potentials between the materials. The addition of a second test sample to each loop did not increase the test sensitivity and may produce confounding results, and thus a single test sample per loop is recommended.

Engineering↗

Testing of Materials and Coatings at up to 1150°C and 300 bar for use in Oxy-Combustion Turbine

Various materials that may be used in a supercritical carbon dioxide (sCO2) oxy-fuel turbine in the 150-300 MWe size range are being evaluated in various environments of interest. The inlet of the turbine must be capable of 1,150 °C at 300 bar and the exhaust temperature is expected to be within the 725-775 °C range. The design requirements are pushing the known limits of high temperature materials. Little is known about the oxidation of the metallic alloys considered for turbine nozzles and blades or about the resilience of thermal management solutions, such as thermal barrier coatings (TBC), required to accommodate these high temperatures. The combinations of high temperature resistant materials and coatings must be tested in sCO2 to evaluate their reliability in an oxy-fuel turbine environment. A total of 13 alloys were chosen to be tested. They included bare samples, with nano deposited MCrAlY bond coat only, or with the addition of a TBC. A unique test facility was developed to expose those materials in sCO2 at up to 300 bar and 1150 °C for up to 5,000 hours. This was accomplished by placing an induction heater inside an autoclave to achieve those high temperature locally while the pressurized vessel is cooled externally. The specimens are weighed before and after exposure to determine the oxidation rate. The integrity, morphology, and composition of some of the coatings and thermally grown oxide will be investigated by scanning electron microscopy (SEM). This paper presents the up-to-date results of the testing coated and uncoated superalloys in sCO2 at up to 1150 °C and up to 300 bar performed at Southwest Research Institute.

Bocher, Florent↗

Experimental Findings on Minor Actinide and Lanthanide Separations using Ion Exchange

During FY14, experimental work focused in the following areas: (1) synthesis, characterization and testing of ion-exchange materials and (2) investigating methods to oxidize americium(III) in dilute nitric acid using peroxydisulfate. Ion-exchange materials tested at SRNL included antimony silicates. Inorganic and hybrid ion-exchange materials tested previously in this project are limited to a pH of about 2. In more concentrated acid solutions, the ion-exchange material is chemically unstable or exhibits poor ion-exchange performance for metal ions. FY14 research focused on testing antimony silicates, which had been reported to exhibit good ion-exchange in 0.2 – 1.0 M nitric acid and some ion-exchange capacity in as high as 3 M nitric acid. Performance testing of archived antimony silicate samples from Prof. R. Harjula (U. Helsinki) and freshly prepared samples showed very low affinity for lanthanide ions in 0.1, 1.0 and 3.0 M nitric acid. Tests carried out in FY14 continued work initiated the previous year to understand the effects that Pu(IV) and nitrite have on the oxidation of Am(III) by peroxydisulfate. Findings indicate that both Pu(IV) and nitrite are oxidized by peroxydisulfate. Consequently, an excess of peroxydisulfate is needed to maximize the conversion of Am(III) to Am(V).

Hobbs, D. T.↗

Fusion Advanced Design Studies

During the January 1, 2013 – December 31, 2015 contract period, the UW Fusion Technology Institute personnel have actively participated in the ARIES-ACT and FESS-FNSF projects, led the nuclear and thermostructural tasks, attended several project meetings, and participated in all conference calls. The main areas of effort and technical achievements include updating and documenting the nuclear analysis for ARIES-ACT1, performing nuclear analysis for ARIES-ACT2, performing thermostructural analysis for ARIES divertor, performing disruption analysis for ARIES vacuum vessel, and developing blanket testing strategy and Materials Test Module for FNSF.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Initial development of an in-situ, passive material surveillance test article for monitoring high temperature reactor structural components

This report describes the development of a family of passively-actuated surveillance test articles, suitable for use in an in-situ reactor test program monitoring the degradation in structural material properties caused by the reactor environment. The test articles apply creep-fatigue-type cyclic load to a test section driven by changes in the reactor coolant temperature converted to mechanical force by differential thermal expansion. The report describes three types of test articles, all of which apply the load to a 316H test section using Alloy 617 as the driver material. The three types of specimens each serve a unique purpose: (1) initial proof-of-concept, (2) validation of the models used to size the specimens to achieve a given strain range, and (3) demonstration that the articles can be miniaturized for use in an actual operating reactor. In addition to the specimen design, fabrication, and testing, this report describes the outline of two types of in-situ monitoring programs, using the test article. Monitoring programs such as these could be a critical component in gaining regulator acceptance for Molten Salt Reactor (MSR) designs using structural materials for which there is little long-term experimental environmental testing or operating experience available for calibrating the component structural design.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Accelerated computation of lattice thermal conductivity using neural network interatomic potentials

We report with the development of the density functional theory (DFT) and ever-increasing computational capacity, an accurate prediction of lattice thermal conductivity based on the Boltzmann transport theory becomes computationally feasible, contributing to a fundamental understanding of thermal conductivity as well as a choice of the optimal materials for specific applications. However, steep costs in evaluating third-order force constants limit the theoretical investigation to crystals with high symmetry and few atoms in the unit cell. Currently, machine learning potentials are garnering attention as a computationally efficient high-fidelity model of DFT, and several studies have demonstrated that the lattice thermal conductivity could be computed accurately via the machine learning potentials. However, test materials were mostly crystals with high symmetries, and the applicability of machine learning potentials to a wide range of materials has yet to be demonstrated. Furthermore, establishing a standard training set that provides consistent accuracy and computational efficiencies across a wide range of materials would be useful. To address these issues, herein we compute lattice thermal conductivities at 300 K using neural network interatomic potentials. As test materials, we select 25 materials with diverse symmetries and a wide range of lattice thermal conductivities between 10 -1 and 10 3 Wm -1 K -1 . Among various choices of training sets, we find that molecular dynamics trajectories at 50–700 K consistently provide results at par with DFT for the test materials. In contrast to pure DFT approaches, the computational cost in the present approach is uniform over the test materials, yielding a speed gain of 2–10 folds. When a smaller reduced training set is used, the relative efficiency increases by up to ~50 folds without sacrificing accuracy significantly. The current work will broaden the application scope of machine learning potentials by establishing a robust framework for accurately computing lattice thermal conductivity with machine learning potentials.

36 MATERIALS SCIENCE↗