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All sources NASA NTRS DOE OSTI

DOE OSTI2018

Grain Boundary Diffusion Characterized by KPFM

Materials aging is a high-consequence failure mode in electronic systems. Such mechanisms can degrade the electrical properties of connectors, relays, wire bonds, and other interconnections. Lost performance will impact, not only that of the device, but also the function and reliability of next-level assemblies and the weapons system as a whole. The detections of changes to materials surfaces at the nanometer-scale resolution, provides a means to identify aging processes at their early stages before they manifest into latent failures that affect system-level performance and reliability. Diffusion will be studied on thin films that undergo accelerated aging using the nanometer scale characterization technique of Frequency Modulated Kelvin Probe Force Microscopy (FM-KPFM). The KPFM provides a relatively easy, non-destructive methodology that does not require high-vacuum facilities to obtain nanometer spatial resolution of surface chemistry changes. The KPFM method can provide the means to measure surface, and near-surface, elemental concentrations that allow the determination of diffusion rate kinetics. These attributes will be illustrated by assessing diffusion in a thin film couple. Validation data will obtained from traditional techniques: (a) Auger electron spectroscopy (AES), x-ray fluorescence (XRF), and xray photoelectron spectroscopy (XPS).

36 MATERIALS SCIENCE↗

DOE OSTI2018

Grain Boundary Diffusion Characterized by KPFM

36 MATERIALS SCIENCE↗

DOE OSTI2017

Sandia Dynamic Materials Program Strategic Plan.

Materials in nuclear and conventional weapons can reach multi-megabar pressures and 1000s of degree temperatures on timescales ranging from microseconds to nanoseconds. Understanding the response of complex materials under these conditions is important for designing and assessing changes to nuclear weapons. In the next few decades, a major concern will be evaluating the behavior of aging materials and remanufactured components. The science to enable the program to underwrite decisions quickly and confidently on use, remanufacturing, and replacement of these materials will be critical to NNSA’s new Stockpile Responsiveness Program. Material response is also important for assessing the risks posed by adversaries or proliferants. Dynamic materials research, which refers to the use of high-speed experiments to produce extreme conditions in matter, is an important part of NNSA’s Stockpile Stewardship Program.

36 MATERIALS SCIENCE↗

NASA NTRS1974

The effect of microstructure on the fracture toughness of titanium alloys

The microstructure of the alpha titanium alloy Ti-5Al-2.5Sn and the metastable beta titanium alloy Beta 3 was examined. The material was from normal and extra low interstitial grade plates which were either air-cooled or furnace-cooled from an annealing treatment. Beta 3 was studied in alpha-aged and omega-aged plates which were heat treated to similar strength levels. Tensile and plane strain fracture toughness tests were conducted at room temperature on the alpha-aged material. The microstructure and fracture mechanisms of alloys were studied using optical metallography, electron microscopy, microprobe analyses, and texture pole figures. Future experiments are described.

Vanstone, R. H.↗

DOE OSTI2021

Tritium embrittlement of austenitic stainless-steel tubing at low helium contents

Austenitic stainless steels are the standard materials for containment of hydrogen and tritium because of their resistance to mechanical property degradation in those environments. The mechanical performance of the primary containment material is critical for tritium handling, processing, and storage, thus comprehensive understanding of the processes of tritium embrittlement is an enabling capability for fusion energy. This work describes the investigation of the effects of low levels of tritium-decay-helium ingrowth on 304 L tubes. Long-term aging with tritium leads to high helium contents in austenitic stainless steels and can reduce fracture toughness by 95 %, but the details of behavior at low helium contents are not as well characterized. Here, we present results from tensile testing of tritium pre-charged 304 L tube specimens with a variety of starting microstructures that all contain a low level of helium. The results of the tritium exposed-and-aged materials are compared to previously reported results on similar specimens tested in an unexposed condition as well as the hydrogen precharged condition. Tritium precharging and aging for a short duration resulted in increased yield strengths, ultimate tensile strengths and slightly increased elongation to failure, comparable to higher concentrations of hydrogen precharging.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2021

Tribology Test Bed: NiWC3b Cermet, Chloride Salts (Technical Report)

In this project, the best material and processes that we have available now are used build a pump for validation testing and to be able to provide a quotation for a pump for the Gen3 CSP Phase 3 test facility. Enough high temperature and aged material data is collected to be able to safely design a pump with a high level of confidence of good performance. Manufacturing processes for the nano-composite material including spray coating and joining methods are investigated. These processes enable application of this novel material to pump components.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Static Corrosion Summary: Static Corrosion Testing, Haynes 230 Recession Rate, Chloride Salts

36 MATERIALS SCIENCE↗

DOE OSTI2021

Validation Salt Pump: NiWC3B Cermet, H230, Chloride Salts (Technical Report)

36 MATERIALS SCIENCE↗

DOE OSTI2015

Photo-oxidation of Polymers Synthesized by Plasma and Initiated CVD

Plasma polymers are often limited by their susceptibility to spontaneous and photo-oxidation. We show that the unusual photoluminescence (PL) behavior of a plasma polymer of trans-2-butene is correlated with its photoluminescence strength. These photo-processes occur under blue light illumination (λ=405 nm), distinguishing them from traditional ultraviolet degradation of polymers. These photo-active defects are likely formed during the plasma deposition process and we show that a polymer synthesized using initiated (i)CVD, non-plasma method, has 1000× lower PL signal and enhanced photo-stability. In conclusion, non-plasma methods such as iCVD may therefore be a route to overcoming material aging issues that limit the adoption of plasma polymers.

36 MATERIALS SCIENCE↗

NASA NTRS2000

Laboratory investigation of the contribution of complex aromatic/aliphatic polycyclic hybrid molecular structures to interstellar ultraviolet extinction and infrared emission

We have demonstrated by experiment that, in an energetic environment, a simple polycyclic aromatic hydrocarbon (PAH) such as naphthalene will undergo chemical reactions that produce a wide array of more complex species (an aggregate). For a stellar wind of a highly evolved star (post-asymptotic giant branch [post-AGB]), this process would be in addition to what is expected from reactions occurring under thermodynamic equilibrium. A surprising result of that work was that produced in substantial abundance are hydrogenated forms that are hybrids of polycyclic aromatic and polycyclic alkanes. Infrared spectroscopy described here reveals a spectral character for these materials that has much in common with that observed for the constituents of circumstellar clouds of post-AGB stars. It can be demonstrated that a methylene (-CH2-) substructure, as in cycloalkanes, is the likely carrier of the 6.9 microns band emission of dust that has recently been formed around IRAS 22272+5433, NGC 7027, and CPD -56 8032. Ultraviolet spectroscopy previously done with a lower limit of 190 nm had revealed that this molecular aggregate can contribute to the interstellar extinction feature at 2175 angstroms. We have now extended our UV spectroscopy of these materials to 110 nm by a vacuum ultraviolet technique. That work, described here, reveals new spectral characteristics and describes how material newly formed during the late stages of stellar evolution could have produced an extinction feature claimed to exist at 1700 angstroms in the spectrum of HD 145502 and also how the newly formed hydrocarbon material would be transformed/aged in the general interstellar environment. The contribution of this molecular aggregate to the rise in interstellar extinction at wavelengths below 1500 angstroms is also examined. The panspectral measurements of the materials produced in the laboratory, using plasmas of H, He, N, and O to convert the simple PAH naphthalene to an aggregate of complex species, provide insight into possible molecular structure details of newly formed hydrocarbon-rich interstellar dust and its transformation into aged material that becomes resident in the interstellar medium. Specifically the presence of naphthalene-like and butadiene-like conjugated structures as chromophores for the 2175 angstroms ultraviolet extinction feature is indicated.

NASA Discipline Exobiology↗

DOE OSTI2017

Enhanced electrical penetration components meet the high safety standards required for China's HTR-PM Shidaowan and generation mPower small modular reactors - 300

Enhanced glass-to-metal feedthroughs will be used to carry key instrumentation and control (I and C) signals in China's high-temperature, gas-cooled pebble-bed modular reactor (HTR-PM) at Shidaowan, and in Small Modular Reactor (SMR) prototyping. Chinergy Co., Ltd and Jiamusi Electric Machine Co., Ltd will use the feedthroughs, also called electrical penetration assemblies (EPAs), at the Shidaowan twin-reactor high temperature reactor (HTR). These feedthroughs are manufactured using specialized processes that make them far more robust than counterparts made with organic or ceramic materials. Improved EPAs manufactured by SCHOTT are the only feedthrough solution that can be used in the primary loop of an HTR because organic seals cannot withstand the high temperatures and pressures of this environment. Glass-to-metal seals (GTMS) are made using inorganic, non-aging materials which enable a virtually unlimited lifespan in high-temperature, high-radiation and high-pressure applications. This I and C technology package is being enhanced by the development and testing of new mineral-insulated (MI) cable connectors and EPAs made of crystallized glass-ceramic combined with superalloys. The EPAs have a maintenance-free lifespan of over 60 years, preventing any outage time related to these components and subsequently reducing costs associated with shutdowns. They are far more robust than organic seals and provide increased safety at a lower lifetime cost. Resistance against high pressure and high temperature are especially ideal qualities that make EPAs a valuable choice for environments with high standards for fire protection, such as nuclear plants, subsea oil drilling, or any other underwater application. Due to their significant offering of safety-relevant qualities, the EPAs have also been chosen by BWXT for implementation in its mPower SMR. Small modular reactor requirements are complex and very challenging but are met by the new EPA components, which will help form a strong I and C safety chain. Unlike ordinary compression glass-to-metal seals, GTMS with crystallized glass-ceramic have the ability to withstand temperatures of over 350 deg. C / 662 deg. F and operating pressures of 3500 bar. Furthermore, their lifetime is qualified for up to 60 years, including pressure and radiation requirements in accordance with the latest IEC/IEEE standards. Higher-specification EPAs and MI cable connectors have been designed into severe accident I and C instruments, including advanced hydrogen and oxygen sensors that exceed the challenging requirements of both HTR and SMR applications. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2024

Monitoring of Photovoltaic (PV) Performance and Degradation: Integrated Renewable Energy Systems (IRES) - PV Monitoring Task

The Integrated Renewable Energy System (IRES) testbed demonstration at the Pacific Northwest National Laboratory (PNNL) Sequim campus includes development of a suite of capabilities for tracking the performance of photovoltaic (PV) renewable energy components located on a floating platform (floating PV) and on a shoreline building rooftop. The marine environment represents potentially harsh and corrosive conditions for PV modules. Compared to terrestrial PV, potential concerns for offshore PV arising from high humidity and occasional contact with saltwater, marine wildlife, and aquaculture. These environmental factors can reduce electricity generation efficiency and increase the risk of electrical faults, polymer insulation or jacketing degradation and hydrolysis of the PV cell encapsulant materials. Offshore PV modules may also be exposed to lower temperatures and buoyant and vibrating motions with a floating platform. It is not clear how the long-term performance of floating PV will be affected by these factors. To understand expected energy generation through solar cells on a floating platform, monitoring of the performance of PV modules in the marine environment is needed. This report outlines a plan for long-term testing of IRES PV components utilizing resources of the PNNL Material Aging and Detection (MAaD) Science team and the Marine and Coastal Research Laboratory (MCRL). Equipment applicable for onsite testing and real-time monitoring of the PV performance associated with environmental conditions including temperature, solar irradiance, shading and soiling is included. In case of performance loss, equipment for fault detection, failure analysis, material testing, and further troubleshooting are also available. Through establishment of this capabilities, the enabling IRES project sets the stage for future research to advance off-shore and near-shore energy options for businesses and communities.

14 SOLAR ENERGY↗

DOE OSTI2024

Rapid Predictions of Part Lifetimes in Corrosive Environments, Corrosion

Corrosion challenges persist throughout SNL’s mission areas. The primary difficulty lies in the fact that corrosion typically manifests as isolated, rare events, making preemptive identification exceedingly difficult. Our current strategy for addressing corrosion issues, such as anomalies and SFIs, is similarly isolated and reactive. This method is costly, time-consuming, heavily dependent on a limited number of experts, and offers minimal understanding of the overall damage distribution within the stockpile. This technical challenge is not unique to corrosion but is also prevalent in other material aging phenomena, such as tin-whisker growth in lead-free solder and fatigue failure of springs.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Analysis of Material Properties of Aged Rigid Polyurethane Foam

Polyurethane foams are organic materials which can be classified as mechanically rigid or flexible. They are chemically inert, relatively unaffected by the presence of water (cracking, swelling, absorption), and can be manufactured in densities from 3-40 lb/ft 3 . In addition, polyurethane foams have exceptional mechanical and thermal properties, which support use of polyurethane foams in the 9977 shipping packages. These packages are designed for shipment of special nuclear material and are approved for storage in the K-area complex (KAC) at Savannah River Site. Through the analysis of conditioned foams, a service life ofFR-3700 can be estimated for the storage of the 9977 packages. Thus, considering anticipated temperatures of the 9977 packages in the KAC, FR-3700 was conditioned at 160°F, 185°F, 215°F, 250°F, and 160°F with 50% relative humidity, which remains within the service temperature of-320°F - 250°F of the FR-3700 foam in the 9977 packages. Prior studies have analyzed foams after 7, 20, and 30 months of conditioning with the current study analyzing foams up to 55 months of conditioning. Considering the limited information on the effects of radiation on FR-3700, samples were irradiated with a cobalt-60 source at a high and low dose rate of 90.9 krad/hr and 16.67 krad/hr, respectively, to examine the effects of irradiation and dose rate on thermal properties. It was found that foams conditioned up to 55 months had comparable heat capacity values to FR-3700, with a slight increase due to humidity. Results suggest that fire additives began decomposing at higher conditioning temperatures, reducing the average percent mass loss. Overall, irradiation and humidity had minimal effects on thermal properties of FR-3700.

36 MATERIALS SCIENCE↗

DOE OSTI2016

In-air and pressurized water reactor environment fatigue experiments of 316 stainless steel to study the effect of environment on cyclic hardening

Argonne National Laboratory (ANL), under the sponsorship of Department of Energy’s Light Water Reactor Sustainability (LWRS) program, is trying to develop a mechanistic approach for more accurate life estimation of LWR components. In this context, ANL has conducted many fatigue experiments under different test and environment conditions on type 316 stainless steel (316SS) material which is widely used in the US reactors. Contrary to the conventional S~N curve based empirical fatigue life estimation approach, the aim of the present DOE sponsored work is to develop an understanding of the material ageing issues more mechanistically (e.g. time dependent hardening and softening) under different test and environmental conditions. Better mechanistic understanding will help develop computer-based advanced modeling tools to better extrapolate stress-strain evolution of reactor components under multi-axial stress states and hence help predict their fatigue life more accurately. In this paper (part-I) the fatigue experiments under different test and environment conditions and related stress-strain results for 316 SS are discussed. In a second paper (part-II) the related evolutionary cyclic plasticity material modeling techniques and results are discussed.

Cyclic plasticity material modeling↗

DOE OSTI2025

Bio-Oil Impact on Water Diffusion and Durability of Bitumen: Influence of Aging and Salinity

Bio-oils derived from inexpensive biomass offer environmentally friendly options for modifying bitumen for improved durability or rejuvenating aged material, although their impact on bitumen moisture resistance can be mixed. A better understanding of water diffusion into bitumen and its interactions with bio-oil compounds would aid the development of effective bio-oils. In this study, the effect of water exposure on bio-oil-modified bitumen blends was examined by de-wetting contact angle measurements and differential FTIR spectroscopy. The bio-oils improved the anti-stripping behavior of the bitumen but also increased water absorption which could weaken cohesive strength. Short-term thermal aging increased water diffusion for all bitumen blends including the control, probably due to the presence of more oxidized compounds. Negative peaks of alkanes and polar groups in the differential FTIR data suggest the co-diffusion of surfactant molecules towards the bitumen-water interface. Basic pH increased de-wetting of some bitumen blends from silica, possibly by attacking the silica surface itself. The presence of salt in solution altered the bitumen surface composition through the formation of salt complexes with bitumen or bio-oil compounds. In particular, the formation of calcium-carboxylate complexes appeared to greatly improve anti-stripping effects of bio-oils. Water diffusion into most of the bitumen blends was insensitive to pH or salt concentration except for a few notable outliers. Identifying the compounds responsible for increasing or decreasing water diffusion in these outlier cases would be valuable developing future bio-oil formations that avoid or promote those compounds.

Hung, Albert M.↗

DOE OSTI2017

Accelerated materials evaluation for nuclear applications

This report addresses the opportunities and complexities of using materials test reactors with high neutron fluxes to perform accelerated studies of material aging in power reactors operating at lower neutron fluxes and with different neutron flux spectra. Radiation damage and gas production in different reactors have been compared using the code, SPECTER. This code provides a common standard from which to compare neutron damage data generated by different research groups using a variety of reactors.

36 MATERIALS SCIENCE↗

DOE OSTI2014

Predicted Radiation Output from Several Kilograms of Plutonium Oxide

Neutron and gamma signatures from 3.44 kg of plutonium oxide were predicted with MCNP6 in anticipation of a passive diagnostic measurement campaign. Calculated radiation fields are visualized through use of “FMESH” type tallies. This work is effectively an extension of previous efforts and application of MISC for the photon source term is the main advancement. Large sources of modeling uncertainty include physical can dimensions and thus internal volume and density estimates. Material age is unknown and will also affect the passive gamma signature. The measurement campaign will provide information for model refinement and subsequent simulations. The authors have requested passive data collection on the pair of cans with the largest and smallest mass and such data will be valuable for benchmarking purposes.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗