Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Performance Rating Method”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

The Impact of Intensity Modulated Radiation Therapy on Hospitalization Outcomes in the SEER-Medicare Population With Anal Squamous Cell Carcinoma

Purpose: We examined the impact of intensity modulated radiation therapy (IMRT) on hospitalization rates in the Surveillance, Epidemiology, and End Results (SEER)–Medicare population with anal squamous cell carcinoma (SCC). Methods and Materials: We performed a retrospective cohort study using the SEER-Medicare database. We identified patients with nonmetastatic anal SCC diagnosed between 2001 and 2011 and treated with chemoradiation therapy. We assessed the relation between IMRT and first hospitalization by use of a multivariate competing-risk model, as well as instrumental variable analysis, using provider IMRT affinity as our instrument. Results: Of the 1165 patients included in our study, 458 (39%) received IMRT. IMRT use increased over time and was associated more with regional and provider characteristics than with patient characteristics. The 3- and 6-month cumulative incidences of first hospitalization were 41.9% (95% confidence interval [CI], 37.3%-46.4%) and 47.6% (95% CI, 43.0%-52.2%), respectively, for the IMRT cohort and 46.7% (95% CI, 43.0%-50.4%) and 52.1% (95% CI, 48.4%-55.7%), respectively, for the non-IMRT cohort. IMRT was associated with a decreased hazard of first hospitalization compared with 3-dimensional radiation techniques (hazard ratio, 0.70; 95% CI, 0.58-0.84; P=.0002). Instrumental variable analysis suggested an even greater reduction in hospitalizations with IMRT after controlling for unmeasured confounders. There was a trend toward improved overall survival with IMRT, with an adjusted hazard ratio of 0.77 (95% CI, 0.59-1.00; P=.05). Conclusions: The use of IMRT is associated with reduced hospitalizations in elderly patients with anal SCC. Further work is warranted to understand the long-term health and cost impact of IMRT, particularly for patient subgroups most at risk of toxicity and hospitalization.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Perspective: Tipping the scales: Search for drifting constants from molecular spectra

Transitions in atoms and molecules provide an ideal test ground for constraining or detecting a possible variation of the fundamental constants of nature. In this perspective, we review molecular species that are of specific interest in the search for a drifting proton-to-electron mass ratio μ. In particular, we outline the procedures that are used to calculate the sensitivity coefficients for transitions in these molecules and discuss current searches. These methods have led to a rate of change in μ bounded to 6 × 10{sup −14}/yr from a laboratory experiment performed in the present epoch. On a cosmological time scale, the variation is limited to |Δμ/μ| < 10{sup −5} for look-back times of 10–12× 10{sup 9} years and to |Δμ/μ| < 10{sup −7} for look-back times of 7× 10{sup 9} years. The last result, obtained from high-redshift observation of methanol, translates into μ{sup .}/μ=(1.4±1.4)×10{sup −17}/yr if a linear rate of change is assumed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

SU-E-J-70: Evaluation of Multiple Isocentric Intensity Modulated and Volumetric Modulated Arc Therapy Techniques Using Portal Dosimetry

Purpose: To develop a method for verification of dose distribution in a patient during treatment using multiple isocentric Intensity modulated and volumetric modulated arc therapy techniques with portal dosimetry. Methods: Varian True Beam accelerator, equipped with an aS1000 megavoltage electronic portal imaging device (EPID) has an integrated image mode for portal dosimetry (PD). The source-to-imager distance was taken at 150 cm to avoid collision to the table. Fourteen fractions were analyzed for this study. During shift in a single plan from one isocenter to another isocenter, EPID also shifted longitudinally for each field by taking the extent of divergence of beam into the consideration for EPID distance of 150cm. Patients were given treatment everyday with EPID placed in proper position for each field. Several parameters were obtained by comparing the dose distribution between fractions to fraction. The impact of the intra-fraction and inter-fraction of the patient in combination with isocenter shift of the beams were observed. Results: During treatment, measurements were performed by EPID and were evaluated by the gamma method. Analysis was done between fractions for multiple isocenter treatments. The pass rates of the gamma analysis with a criterion of 3% and 3 mm for the 14 fractions were over 97.8% with good consistency. Whereas maximum gamma exceeded the criteria in few fractions (in<1 cc vol). Average gamma was observed in the criteria of 0.5%. Maximum dose difference and average dose differences were less than 0.22 CU and 0.01 CU for maximum tolerance of 1.0 CU and 0.2 CU respectively. Conclusion: EPID with extended distance is ideal method to verify the multiple isocentric dose distribution in patient during treatment, especially cold and hot spots in junction dose. Verification of shifts as well as the dose differences between each fraction due to inter-fraction and intra-fraction of the patient can be derived.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Dataset for: Price Controls for Scarcity Events in Real-Time and Transactive Energy Systems

Real time pricing (RTP) is often promoted as a mechanism to improve the economic efficiency of the electricity system. However, many regulators have been hesitant to adopt RTP due to concerns about exposing customers to extreme price swings. To balance these concerns, this paper proposes a methodology for establishing price controls, based on the supply of demand-side flexibility in the system. As an illustrative example, we measure price responsiveness using an agent-based simulation model that is representative of the ERCOT market. The model is composed of a distribution feeder that has 250 customers with active agents controlling their HVAC systems in response to the historical ERCOT RTP with an artificially added high-price event. These agents are subjected to increasing electricity prices during the event, which we then use to create a supply curve for demand-side resources in our modeled scarcity event. We set potential price caps at points on the supply curve where customers’ have exhausted their flexible capacity. Using historical prices, we examine the systemic costs of these price caps, and present regulatory options for recouping them. Utilities and regulators interested in limiting consumer risk from dynamic pricing can utilize these methods to develop rate structures and encourage conservation. The attached data upload allows for the duplication or modification of the analysis performed in this study.

Kerby, Jessica R↗
DOE OSTI2014

An efficient particle Fokker–Planck algorithm for rarefied gas flows

This paper is devoted to the algorithmic improvement and careful analysis of the Fokker–Planck kinetic model derived by Jenny et al. [1] and Gorji et al. [2]. The motivation behind the Fokker–Planck based particle methods is to gain efficiency in low Knudsen rarefied gas flow simulations, where conventional direct simulation Monte Carlo (DSMC) becomes expensive. This can be achieved due to the fact that the resulting model equations are continuous stochastic differential equations in velocity space. Accordingly, the computational particles evolve along independent stochastic paths and thus no collision needs to be calculated. Therefore the computational cost of the solution algorithm becomes independent of the Knudsen number. In the present study, different computational improvements were persuaded in order to augment the method, including an accurate time integration scheme, local time stepping and noise reduction. For assessment of the performance, gas flow around a cylinder and lid driven cavity flow were studied. Convergence rates, accuracy and computational costs were compared with respect to DSMC for a range of Knudsen numbers (from hydrodynamic regime up to above one). In all the considered cases, the model together with the proposed scheme give rise to very efficient yet accurate solution algorithms.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Evaluation of clear-sky and satellite-derived irradiance data for determining the degradation of photovoltaic system performance

Knowing the degradation in performance of a photovoltaic (PV) system over time is important for estimating the lifetime energy produced and the financial return. A key parameter for normalizing performance and determining degradation is the plane-of-array (POA) irradiance. Because accurate long-term POA measurements are not always readily available, three methods of providing irradiance data for determining the degradation rate of PV systems were evaluated—a method using irradiance data modeled with the Ineichen clear-sky model and monthly Linke turbidity coefficients, a method using the supplemental clear-sky irradiance data from the National Solar Radiation Data Base (NSRDB), and a method using the NSRDB solar irradiance data for both cloudy and clear-sky conditions (all-sky). The irradiance data from the three methods were evaluated using measured irradiance data from 1998 through 2018 for the seven-station SURFRAD network and for 3-, 5-, and 10-year periods that might be used for evaluating PV system performance. Only the two clear-sky methods for the 10-year periods had less uncertainty with respect to determining PV system degradation than the expected median degradation rate for PV systems of -0.5%/year to -0.6%/year. Shorter periods and the all-sky method had larger uncertainties, making their use questionable for determining the degradation rates of PV systems.

14 SOLAR ENERGY↗
DOE OSTI2018

Ruthenium oxide nanostring clusters anchored Graphene oxide nanocomposites for high-performance supercapacitors application

Highlights: • GO-RuO{sub 2} nanocomposites were synthesized by simple hydrothermal method. • GO-RuO{sub 2} nanocomposites were characterized by XRD, SEM, TEM and EDS. • GO-RuO{sub 2} nanostring composite has shown a maximum specific capacitance of 859 Fg{sup −1} at the scan rate of 5 mVs{sup −1}. • GO-RuO{sub 2} nanostring composite electrode exhibits tremendous cyclic stability. - Abstract: Here, we report simple hydrothermal method for the preparation of Graphene oxide (GO) is embellished with nanostring clusters of ruthenium oxide (GO-RuO{sub 2}). The structure of the nanocomposite material was ascertained using X-ray diffraction (XRD), Raman spectroscopy, Scanning electron spectroscopy (SEM), Energy dispersive spectroscopy (EDS) and Transmission spectroscopy (TEM). The supercapacitor performance of the nanocomposites was investigated in acidic electrolyte, 1.0 M H{sub 2}SO{sub 4}, in a three-electrode setup. GO-RuO{sub 2} nanostring composite has shown a maximum specific capacitance of 859 Fg{sup −1} at the scan rate of 5 mVs{sup −1} using Cyclic voltammetry (CV) and by using Chronopotentiometry (CP) the specific capacitance towered up to 512 Fg{sup −1} at a current density of 2.5 Ag{sup −1}. Further, the material also possesses a high energy density of 246 Wh kg{sup -1}with a maximum power density of 1028 W kg{sup -1}. GO-RuO{sub 2} nanostring composite electrode exhibits tremendous cyclic stability with the specific capacitance retention of nearly 99% of the initial capacitance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2013

Diagnostic Cardiac Catheterization Using the MEDRAD Avanta™ Fluid Management System as Compared to the Traditional Manual Injection Method

Nearly 4 million patient procedures performed annually in US cardiac catheterization laboratories utilize contrast media to achieve vessel opacification. The amount of contrast media used is variable and depends on the complexity of the procedure, the method of contrast delivery as well as the skill-level of the operator. Since the total amount of contrast used for each procedure can have both patient safety and economic implications, it is essential for cardiologists to have the ability to control contrast delivery such that optimal angiographic image quality is achieved using the least amount of contrast. Although the complication rate associated with cardiac catheterization remains low, the most common serious complication, contrast-induced nephropathy (CIN), is associated with poor prognosis and a high mortality rate. Numerous interventional strategies for preventing and reducing the severity of CIN have demonstrated varying degrees of clinical benefit, but none has been shown to reliably prevent this serious complication. To date, the most effective approach for reducing the risk of CIN is to properly hydrate the patient and to minimize the amount of contrast media administered. Automated injection systems are intended for use in virtually all cardiac catheterization procedures and have numerous features which can provide potential advantages over traditional methods. With automated injection technology the operator is able to control and precisely monitor contrast delivery. Additionally, the MEDRAD Avanta Fluid Management Injection System utilizes a sterile contrast reservoir which eliminates the need to discard unused contrast in individual opened containers following each procedure. Considering that an average of 50% of opened contrast media is wasted using manual injection methods, this savings can provide a substantial economic benefit. Automated systems also facilitate the use of smaller (5 French) catheter sizes. Precise flow control and the use of smaller diameter catheters have both been shown to reduce the volume of contrast administered. The use of smaller size catheters also permits more rapid hemostasis, thus allowing shorter ambulation time without the need for costly wound closure devices. These factors can result in enhanced patient satisfaction as well as more efficient management of post-procedure rooms. The intent of this study was to demonstrate that using the MEDRAD Avanta™ Fluid Management Injection System (MEDRAD, INC., Pittsburgh, PA) for coronary diagnostic procedures can produce a reduction in the volume of contrast administered without loss of operational quality or efficiency. In addition, this study will explore procedure time and efficiency in an effort to minimize the amount of ionizing radiation delivered to the patient as well as the diagnostic team members. Study Design This is a post-market study designed to collect data during diagnostic cardiac catheterization when utilizing 5FR or 6FR catheters in conjunction with the Avanta Fluid Management System or a manual manifold injection method control group. A minimum of 420 patients scheduled for diagnostic cardiac catheterization will be enrolled in the study cohort. Patients will be assigned into the following two groups. Group 1: Catheterization with 5FR or 6FR catheters, using the traditional manual manifold injection method for contrast media delivery which is defined as manual hand injection of contrast media through a 3 or 4 port manifold and left ventriculography performed via standard fixed rate power injection. Group 2: Catheterization with 5FR or 6FR catheters, using the MEDRAD Avanta™ system for contrast media delivery. Study endpoints include volume of contrast media administered during diagnostic cardiac catheterization, volume of contrast media wasted post-procedure, procedure time (defined as the time from first catheter insertion to last diagnostic catheter removal), fluoroscopy time and angiographic image quality. The study demonstrated that use of the Advanta system reduced overall contrast utilization by decreasing the amount of contrast administered to the patient and reducing the amount of contrast wasted during preparation and post-procedure clean-up. The quality of the angiographic images and the radiation exposure to the patient were not affected.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Fitting of Failure Rate Data to a Closed Form Solution using Gamma-Poisson Method of Moments

Due to the responsibility and gravity of estimation of nuclear power plant failure rates, it is required that there be consistent and accurate methodology for describing the likelihood of an event occurring. However, the methodology currently employed can vary dependent on the data, as well as subjective conjecture from the expert performing the analysis. The current implementation of the empirical Bayes method to a Gamma-Poisson (GaP) distribution utilizes algorithms to solve for the parameters that do not provide consistent answers. Additionally, to achieve a distribution of the likelihood, the variance of each parameter of the GaP must be determined. There does not exist an exact solution to one of the parameters variance and is typically estimated using techniques like the Kass-Steffey adjustment. Thus a new approach to the problem is proposed, built upon the method of moments for a negative binomial, based upon the work of Bradlow. Using the method of moments approach, we are able to achieve a closed form estimation of the mean and variance for each parameter in the negative binomial distribution. Due to the relationship between the negative binominal and GaP distribution, results can be made between the distributions. The hyper-priors defined assume beta prime distribution which is appropriately informed; the results of this application translate back to the Gamma distribution for easy utilization in SAPHIRE. Additionally several cases are explored using publically available NRC data that considers zero inflated, over dispersed, and Poisson data.

Failure Rate↗
DOE OSTI2016

Verification of BOUT++ by the method of manufactured solutions

BOUT++ is a software package designed for solving plasma fluid models. It has been used to simulate a wide range of plasma phenomena ranging from linear stability analysis to 3D plasma turbulence and is capable of simulating a wide range of drift-reduced plasma fluid and gyro-fluid models. A verification exercise has been performed as part of a EUROfusion Enabling Research project, to rigorously test the correctness of the algorithms implemented in BOUT++, by testing order-of-accuracy convergence rates using the Method of Manufactured Solutions (MMS). We present tests of individual components including time-integration and advection schemes, non-orthogonal toroidal field-aligned coordinate systems and the shifted metric procedure which is used to handle highly sheared grids. The flux coordinate independent approach to differencing along magnetic field-lines has been implemented in BOUT++ and is here verified using the MMS in a sheared slab configuration. Finally, we show tests of three complete models: 2-field Hasegawa-Wakatani in 2D slab, 3-field reduced magnetohydrodynamics (MHD) in 3D field-aligned toroidal coordinates, and 5-field reduced MHD in slab geometry.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Graphene-modified nanostructured vanadium pentoxide hybrids with extraordinary electrochemical performance for Li-ion batteries

The long-standing issues of low intrinsic electronic conductivity, slow lithium-ion diffusion and irreversible phase transitions on deep discharge prevent the high specific capacity/energy (443 mAh g -1 and 1,550 Wh kg -1 ) vanadium pentoxide from being used as the cathode material in practical battery applications. Here we develop a method to incorporate graphene sheets into vanadium pentoxide nanoribbons via the sol–gel process. The resulting graphene-modified nanostructured vanadium pentoxide hybrids contain only 2 wt. % graphene, yet exhibits extraordinary electrochemical performance: a specific capacity of 438 mAh g -1 , approaching the theoretical value (443 mAh g -1 ), a long cyclability and significantly enhanced rate capability. Such performance is the result of the combined effects of the graphene on structural stability, electronic conduction, vanadium redox reaction and lithium-ion diffusion supported by various experimental studies. Finally, this method provides a new avenue to create nanostructured metal oxide/graphene materials for advanced battery applications.

25 ENERGY STORAGE↗
DOE OSTI2014

Four dimensional hybrid ultrasound and optoacoustic imaging via passive element optical excitation in a hand-held probe

Ultrasonography and optoacoustic imaging share powerful advantages related to the natural aptitude for real-time image rendering with high resolution, the hand-held operation, and lack of ionizing radiation. The two methods also possess very different yet highly complementary advantages of the mechanical and optical contrast in living tissues. Nonetheless, efficient integration of these modalities remains challenging owing to the fundamental differences in the underlying physical contrast, optimal signal acquisition, and image reconstruction approaches. We report on a method for hybrid acquisition and reconstruction of three-dimensional pulse-echo ultrasound and optoacoustic images in real time based on passive ultrasound generation with an optical absorber, thus avoiding the hardware complexity of active ultrasound generation. In this way, complete hybrid datasets are generated with a single laser interrogation pulse, resulting in simultaneous rendering of ultrasound and optoacoustic images at an unprecedented rate of 10 volumetric frames per second. Performance is subsequently showcased in phantom experiments and in-vivo measurements from a healthy human volunteer, confirming general clinical applicability of the method.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Current Efforts in Immobilized Low-Activity Waste Glass Testing to Support the Hanford Site Integrated Disposal Facility - 17119

Cleanup plans for Hanford site high-level radioactive mixed tank waste calls for separating the waste into high-level waste (HLW) and low-activity waste (LAW) fractions. The fractions will be vitrified separately at the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The HLW glass will be sent to an offsite geological disposal facility while the immobilized low-activity waste (ILAW) glass will be disposed at the onsite Integrated Disposal Facility (IDF). In order to inform models used to predict the performance of ILAW glass at IDF, it is necessary to understand the corrosion behavior of the glass. In this paper, we discuss tests that account for the effects of 1) solution chemistry, 2) the ion exchange reaction, and 3) secondary phase formation on the glass dissolution rate. To quantify the effects of solution chemistry, specifically changes in pH, T, and Si concentration, the single-pass flow-through (SPFT) test method is applied. A designed set of these tests results in a set of kinetic rate law parameters that are used in a glass dissolution rate law based on transition-state theory. Furthermore, for SPFT tests with relatively high concentrations of Si, an ion exchange rate is provided. Additionally, through tests such as the pressurized unsaturated flow (PUF) test method, a suite of secondary phases can be compiled. The collection of kinetic rate law parameters, the ion exchange term, and the suite of secondary phases are provided to IDF performance assessment (PA) modelers. Lastly, we present a description of the efforts made to verify and validate the use of these parameters and secondary phases through the use of a field lysimeter present at the Hanford site. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Energy levels, oscillator strengths, line strengths, and transition probabilities in Si-like ions of La XLIII, Er LIV, Tm LV, and Yb LVI

Detailed calculations using the multi-configuration Dirac–Fock (MCDF) method are carried out for the lowest 64 fine-structure levels of the 3s{sup 2}3p{sup 2}, 3s{sup 2}3p3d, 3s3p{sup 3}, 3s3p{sup 2}3d, 3s{sup 2}3d{sup 2}, and 3p{sup 4} configurations in Si-like ions of La XLIII, Er LIV, Tm LV, and Yb LVI. Energies, oscillator strengths, wavelengths, line strengths, and radiative electric dipole transition rates are given for all ions. A parallel calculation using the many-body perturbation theory (MBPT) method is also carried out to assess the present energy levels accuracy. Comparisons are performed between these two sets of energy levels, as well as with other available results, showing that they are in good agreement with each other within 0.5%. These high accuracy results can be used to the modeling and the interpretation of astrophysical objects and fusion plasmas. - Highlights: • Energy levels and E1 transition rates of Si-like ions are presented. • Breit interaction and Quantum Electrodynamics effects are discussed. • Present results should be useful in the astrophysical application and plasma modeling.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Porous CoFe{sub 2}O{sub 4} nanowire arrays on carbon cloth as binder-free anodes for flexible lithium-ion batteries

Highlights: • Hierarchal CoFe{sub 2}O{sub 4} nanowire arrays are directly grown on flexible carbon cloth. • Porous CoFe{sub 2}O{sub 4} nanowires are composed of many nanocrystals of 20–40 nm. • CoFe{sub 2}O{sub 4} nanowire arrays exhibit excellent rate capability and cycling stability. • Integrated CoFe{sub 2}O{sub 4}/carbon cloth electrodes show high flexibility and areal capacity. - Abstract: A three-dimensional CoFe{sub 2}O{sub 4} nanowire array on carbon cloth was fabricated with a hydrothermal method together with a post-annealing treatment. As a binder-free and flexible anode material for LIBs, it showed an improved electrochemical performance with high cycling stability and excellent rate capability. It exhibited an initial discharge capacity of 1615 mAh g{sup −1} and retained a reversible capacity of about 1204 mAh g{sup −1} after 200 cycles at a specific current of 500 mA g{sup −1}. The high capacity, outstanding rate performance and cycling stability can be attributed to the special configuration of hierarchal porous CoFe{sub 2}O{sub 4} nanowires on carbon cloth, which possess many advantages like short diffusion length, easy strain relaxation and fast electron transport. Moreover, the integrated CoFe{sub 2}O{sub 4} nanowires/carbon cloth electrode shows high flexibility and high areal capacity (2.41 mAh cm{sup −2}), which makes it suitable for use as a binder-free anode to build flexible LIBs.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Verification of the Accountability Method as a Means to Classify Radioactive Wastes Processed Using THOR Fluidized Bed Steam Reforming at the Studsvik Processing Facility in Erwin, Tennessee, USA - 13087

Studsviks' Processing Facility Erwin (SPFE) has been treating Low-Level Radioactive Waste using its patented THOR process for over 13 years. Studsvik has been mixing and processing wastes of the same waste classification but different chemical and isotopic characteristics for the full extent of this period as a general matter of operations. Studsvik utilizes the accountability method to track the movement of radionuclides from acceptance of waste, through processing, and finally in the classification of waste for disposal. Recently the NRC has proposed to revise the 1995 Branch Technical Position on Concentration Averaging and Encapsulation (1995 BTP on CA) with additional clarification (draft BTP on CA). The draft BTP on CA has paved the way for large scale blending of higher activity and lower activity waste to produce a single waste for the purpose of classification. With the onset of blending in the waste treatment industry, there is concern from the public and state regulators as to the robustness of the accountability method and the ability of processors to prevent the inclusion of hot spots in waste. To address these concerns and verify the accountability method as applied by the SPFE, as well as the SPFE's ability to control waste package classification, testing of actual waste packages was performed. Testing consisted of a comprehensive dose rate survey of a container of processed waste. Separately, the waste package was modeled chemically and radiologically. Comparing the observed and theoretical data demonstrated that actual dose rates were lower than, but consistent with, modeled dose rates. Moreover, the distribution of radioactivity confirms that the SPFE can produce a radiologically homogeneous waste form. The results of the study demonstrate: 1) the accountability method as applied by the SPFE is valid and produces expected results; 2) the SPFE can produce a radiologically homogeneous waste; and 3) the SPFE can effectively control the waste package classification. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Creep in multi-principal element materials –– A review

The ongoing push towards enhanced energy efficiency and reduced emissions has necessitated the creation of materials with superior performance, especially under extreme conditions. Modern industries, such as aerospace, energy production, and nuclear power, rely heavily on materials that can withstand elevated temperatures without compromising structural integrity. At these heightened temperatures, materials, even when subjected to mechanical stresses well below their yield strength, may experience slow deformation leading to eventual rupture — a phenomenon known as creep. With the expansive design space that comes with the high entropy concept and their reported excellent high temperature strength, multi-principal element materials (MPEMs) have attracted interest in the scientific community for high-temperature applications. Here, this review offers a comprehensive examination of existing studies on creep in MPEMs, which includes multi-principal element−alloys, −bulk metallic glasses, −ceramics, and −superalloys, comparing published findings on MPEMs with pure elements, traditional alloys, bulk metallic glasses, and superalloys. The sub-topics covered include a comparison among different creep-testing methods, creep mechanisms, creep exponents, creep strain rates, activation volume, and creep-activation energy. Modeling efforts for predicting creep behavior of MPEMs are also reviewed. Methods for improving creep resistance by performing heat treatments and/or modifying microstructures are discussed. Overall, the current state of MPEMs has not yet surpassed the creep performance of commercial alloys. Finally, directions for future efforts are suggested, such as experimenting in various controlled environments, expanding the number of compositions tested, exploring advanced manufacturing techniques, and using machine-learning to predict creep properties based on compositions and microstructures.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Leach Testing of Laboratory-Scale Melter Evaporator Condensate Cementitious Waste Forms

Cementitious waste forms immobilizing evaporated AP-105 off-gas condensate were used to determine radionuclide and contaminant leachability in deionized water over a 63-day period. The off-gas condensate was collected during the actual tank AP-105 low activity waste continuous laboratory-scale melter (LSM)) run performed in fiscal year 2018 and was then solidified as a cementitious waste form using the Cast Stone formulation (8 weight percent [wt%] ordinary Portland cement, 45 wt% class F fly ash, 47 wt% blast furnace slag). Here, using the U.S. Environmental Protection Agency Method 1315 leach testing procedure, the release rate of technetium 99 (Tc), iodine-129 (I), nitrate (NO 3 - ), and sodium (Na + ) from two Cast Stone specimens was measured. From these measurements, observed diffusivity values for each constituent were calculated and can be used in future iterations and maintenance of the Integrated Disposal Facility performance assessments. Furthermore, by testing Cast Stone specimens immobilizing off-gas produced while vitrifying actual tank waste, the results of this effort improve the technical defensibility of long-term waste form performance estimates for the Cast Stone formulation. Finally, 99 Tc distribution within a representative waste form at the end of the 63-day leach period as well as bulk mineralogy were determined using solid phase characterization methods.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗