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DOE OSTI2024

Effect of Sample Thickness on the Tensile Strength of Small Graphite Discs

This report formally documents the completion of the Advanced Reactor Technologies (ART) Level 3 Milestone (M3TG-24OR0501054), “Continue activities related to Split Disc-DIC - complete analysis of effect of sample thickness on one fine grain graphite,” due May 31, 2024. Details within this report outline the status of activities aimed at elucidating the effect of sample thickness on the tensile strength measurement using the small-disc, split-disc testing standard in support of the US Department of Energy’s ART Graphite R&D Program. The ASTM D8289, Standard Test Method for Tensile Strength Estimate by Disc Compression of Manufactured Graphite, was developed to provide an alternative means for testing tensile strength on smaller specimens, which are compatible with available irradiation capsule volumes, and other compatibility measurements. ASTM D8289 specifies that acceptable specimen diameter can range from 6 to 12.7 mm and that the maximum allowed sample thickness should be half of the diameter. However, information is limited with respect to the effect of thickness on the measured splitting tensile strength. This report documents efforts to understand the effect of sample thickness on splitting tensile strength. The work involved testing Ø12.7 mm samples of fine-grain graphites 2114 and IG-110 of different thicknesses (6.35, 5, 4, and 3 mm). The digital image correlation (DIC) method was applied to the samples, along with the ASTM D8289 Standard, to help interpret the measured results.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Results for the October 2025 Semiannual Salt Waste Processing Facility Decontaminated Salt Solution Sample

In this Technical Report, the chemical and radionuclide contaminant results from the October 2025 Semiannual sample of the Salt Waste Processing Facility (SWPF) Decontaminated Salt Solution (DSS) salt solution are presented in tabulated form. The information from this characterization will be used by Savannah River Mission Completion (SRMC) for the transfer of aqueous waste from SWPF to the Saltstone Production Facility (SPF) where the waste will be treated and disposed in the Saltstone Disposal Facility. This Technical Report compares results, where applicable, to SPF Waste Acceptance Criteria (WAC) LIMITS and TAR GETS that were established at the time the SWPF DSS sample was obtained. 1 The October 2025 Semiannual sample of the SWPF DSS is a composite from one month of SWPF processing during the Third Quarter Fiscal Year 2025 (3QFY2025) and two months of SWPF processing during the Fourth Quarter Fiscal Year 2025 (4QFY2025).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2017

Delayed Slater determinant update algorithms for high efficiency quantum Monte Carlo

Within ab initio Quantum Monte Carlo simulations, the leading numerical cost for large systems is the computation of the values of the Slater determinants in the trial wavefunction. Each Monte Carlo step requires finding the determinant of a dense matrix. This is most commonly iteratively evaluated using a rank-1 Sherman-Morrison updating scheme to avoid repeated explicit calculation of the inverse. The overall computational cost is therefore formally cubic in the number of electrons or matrix size. To improve the numerical efficiency of this procedure, we propose a novel multiple rank delayed update scheme. This strategy enables probability evaluation with application of accepted moves to the matrices delayed until after a predetermined number of moves, K . The accepted events are then applied to the matrices en bloc with enhanced arithmetic intensity and computational efficiency via matrix-matrix operations instead of matrix-vector operations. Here this procedure does not change the underlying Monte Carlo sampling or its statistical efficiency. For calculations on large systems and algorithms such as diffusion Monte Carlo where the acceptance ratio is high, order of magnitude improvements in the update time can be obtained on both multi- core CPUs and GPUs.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2019

Characterization Results For The July 2018 H-Tank Farm 2h Evaporator Overhead Samples

This report contains the radioanalytical results of the 2H evaporator overhead sample received at Savannah River National Laboratory (SRNL) on July 16, 2018. Specifically, concentrations of 137 Cs, 90 Sr, and 129 I are reported and compared to the corresponding Waste Acceptance Criteria (WAC) limits of the Effluent Treatment Project (ETP) Waste Water Collection Tank (WWCT) (rev. 6). The radionuclide concentrations in the sample were found to be in compliance with the ETP WAC limits.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2019

Characterization Results for the July 2018 H-Tank Farm 2H Evaporator Overhead Samples

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRSDate not supplied

Finite Element Thermal Model for Ultrasonic Welding of Thermoplastic Composites

Ultrasonic welding, UW, is a fast and energy-efficient technique for joining thermoplastic composites. It involves the use of high-frequency mechanical vibrations and a static welding force to melt and join adherends. Ultrasonic welding is an enabling technology to reduce the cost and complexity of in-space construction because lightweight thermoplastic composite components can be packaged compactly for launch and then efficiently assembled using supervised autonomous robotic technologies on site. However, the temperatures in space present challenges to UW, and it is critical that the efficacy of process parameters selected for manufacturing in space is understood prior to launch. To this end, a three-dimensional finite element model is presented in this technical presentation. The model incorporates equations for effects of viscoelastic heating and heat transfer on the welding process. The proposed model is applied to predict the temperature distribution in single lap shear, SLS, samples composed of AS4/PEEK (TC1200) composite that were welded using a terrestrial machine as part of a comprehensive weldability study. Thermocouple and infrared spot sensor data from the SLS samples provide empirical temperature measurements for calibration and validation of the UW thermal model. Calibration and validation of the model is an important step given the significant uncertainties in material properties such as the loss modulus and necessary assumptions in the physics implementations which allow the model to converge in an acceptable amount of time. The validated thermal model can be used to simulate the process for the space environment. Future validation sample testing is planned in a vacuum chamber. The result will be a model capable of guiding process parameter selection to ensure acceptable weld bonds when manufacturing in space.

Josh Fody↗

DOE OSTI2011

Crystal-chemistry of mullite-type aluminoborates Al{sub 18}B{sub 4}O{sub 33} and Al{sub 5}BO{sub 9}: A stoichiometry puzzle

Orthorhombic Al{sub 2}O{sub 3}-rich aluminoborate is an important ceramic material for which two slightly different compositions have been assumed: Al{sub 5}BO{sub 9} (5Al{sub 2}O{sub 3}:B{sub 2}O{sub 3}) and Al{sub 18}B{sub 4}O{sub 33} (9Al{sub 2}O{sub 3}:2B{sub 2}O{sub 3}). The formula Al{sub 18}B{sub 4}O{sub 33} (=Al{sub 4.91}B{sub 1.09}O{sub 9}) was derived from results of chemical analyses when crystal structure data were not yet available. Subsequent structural investigations indicated Al{sub 5}BO{sub 9} composition. Nevertheless, Al{sub 18}B{sub 4}O{sub 33} was still accepted as the correct stoichiometry assuming that additional B replaces 9% Al. Powder samples of both compositions and ones with excess boron were prepared by solid state reactions between {alpha}-Al{sub 2}O{sub 3} and B{sub 2}O{sub 3}/H{sub 3}BO{sub 3} at temperatures above 1100 {sup o}C and single-crystals were grown from flux at 1100 and 1550 {sup o}C. Products were investigated by single-crystal and powder XRD, {sup 11}B and {sup 27}Al solid-state MAS-NMR, Raman and FTIR spectroscopy as well as Laser-ablation ICP-MS. No indication of the predicted 9% B{yields}Al substitution was found. LA ICP-MS indicated 12.36(27) wt% B{sub 2}O{sub 3} corresponding to Al{sub 4.97}B{sub 1.03}O{sub 9}. Hence, the suggested Al{sub 18}B{sub 4}O{sub 33} stoichiometry can be excluded for all synthesized samples. A very low amount of Al vacancies at a five-fold coordinated site are likely, charge balanced by an additional nearby three-fold coordinated B site. All evidences indicate that the title compound should be reported as Al{sub 5-x}B{sub 1+x}O{sub 9} with x<0.038(6), which is close to Al{sub 5}BO{sub 9}. -- Graphical abstract: A chemical composition of Al{sub 18}B{sub 4}O{sub 33}=Al{sub 4.91}B{sub 1.09}O{sub 9}=9Al{sub 2}O{sub 3}:2B{sub 2}O{sub 3} has been assumed for mullite-type aluminoborate with Al{sub 5}BO{sub 9} structure. However, samples prepared by different routes showed compositions close to 5Al{sub 2}O{sub 3}:B{sub 2}O{sub 3}. Display Omitted

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2010

Surfactant-free synthesis and electrochemical properties of chrysanthemum-like InVO{sub 4} hierarchical microstructures

Novel chrysanthemum-like hierarchical microstructures of orthorhombic InVO{sub 4} were synthesized via a hydrothermal route without assistance of any template or organic additive. The chrysanthemum-like InVO{sub 4} microstructures are built up of numerous nanobelts radially aligned around the spherical surface. Based on the structural feature of orthorhombic InVO{sub 4} and the key role of the pH value, a probable mechanism of the etching-splitting growth process induced by H{sup +} ions was proposed to explain the formation of InVO{sub 4} microstructures. Furthermore, the chrysanthemum-like InVO{sub 4} sample shows a high discharge capacity of 608.6 mAh g{sup -1} and acceptable capacity retention when used as an electrode material in lithium ion batteries. The pure orthorhombic phase and unique porous morphology play basic roles in the structural requirement to serve as transport paths for lithium ion.

36 MATERIALS SCIENCE↗

DOE OSTI2017

A practical method to test the validity of the standard Gumbel distribution in logit-based multinomial choice models of travel behavior

Most multinomial choice models (e.g., the multinomial logit model) adopted in practice assume an extreme-value Gumbel distribution for the random components (error terms) of utility functions. This distributional assumption offers a closed-form likelihood expression when the utility maximization principle is applied to model choice behaviors. As a result, model coefficients can be easily estimated using the standard maximum likelihood estimation method. However, maximum likelihood estimators are consistent and efficient only if distributional assumptions on the random error terms are valid. It is therefore critical to test the validity of underlying distributional assumptions on the error terms that form the basis of parameter estimation and policy evaluation. In this paper, a practical yet statistically rigorous method is proposed to test the validity of the distributional assumption on the random components of utility functions in both the multinomial logit (MNL) model and multiple discrete-continuous extreme value (MDCEV) model. Based on a semi-nonparametric approach, a closed-form likelihood function that nests the MNL or MDCEV model being tested is derived. The proposed method allows traditional likelihood ratio tests to be used to test violations of the standard Gumbel distribution assumption. Simulation experiments are conducted to demonstrate that the proposed test yields acceptable Type-I and Type-II error probabilities at commonly available sample sizes. The test is then applied to three real-world discrete and discrete-continuous choice models. For all three models, the proposed test rejects the validity of the standard Gumbel distribution in most utility functions, calling for the development of robust choice models that overcome adverse effects of violations of distributional assumptions on the error terms in random utility functions.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2014

Evaluating the Accuracy and Precision of Multiple Abundance Estimators Using State-Space Models: A Case Study for a Threatened Population of Chinook Salmon in Johnson Creek, Idaho

Abstract Over the last century, Chinook Salmon Oncorhynchus tshawytscha populations in the Pacific Northwest have experienced dramatic declines, leading to many of them being listed as threatened under the Endangered Species Act. The abundance of these threatened populations relative to the thresholds for delisting remains the primary metric for assessing recovery, yet determining the true population abundances from multiple survey types with unknown levels of accuracy and precision remains difficult. The abundance of the spring–summer Chinook Salmon population in Johnson Creek, Idaho, has been measured using a mark–recapture survey and three different redd count surveys (RCSs) that vary temporally and spatially. Using a state-space model, we determined the accuracy and precision of each survey type by decoupling the observation error of the survey from the process error describing the annual variability in the true population abundance. We then extended the results of the model to determine the risk of managers’ incorrectly delisting the population (a type I error) or incorrectly keeping it listed (a type II error). Finally, we show that salmon managers with data-limited populations (primarily those with only single-pass index RCSs) might use the results of our risk analysis to determine whether expanding survey efforts to minimize management risks is appropriate when they are confronted with dwindling financial resources. For example, we determined that although both the multiple-pass extended RCS (CV = 0.06) and mark–recapture surveys (CV = 0.14) provide unbiased estimates of salmon abundance in Johnson Creek, the mark–recapture study can have annual costs that are 30–100 times greater. Managers may determine that directing research funds toward acquiring information unique to weir-based mark–recapture surveys (i.e., migration timing, good genetics samples, etc.) may not be justified for all populations. Received October 7, 2013; accepted March 5, 2014

Chasco, Brandon E.↗

DOE OSTI2010

ON THE DEARTH OF COMPACT, MASSIVE, RED SEQUENCE GALAXIES IN THE LOCAL UNIVERSE

We set out to test the claim that the recently identified population of compact, massive, and quiescent galaxies at z {approx} 2.3 must undergo significant size evolution to match the properties of galaxies found in the local universe. Using data from the Sloan Digital Sky Survey (SDSS; Data Release 7), we have conducted a search for local red sequence galaxies with sizes and masses comparable to those found at z {approx} 2.3. The SDSS spectroscopic target selection algorithm excludes high surface brightness objects; we show that this makes incompleteness a concern for such massive, compact galaxies, particularly for low redshifts (z {approx}< 0.05). We have identified 63 M{sub *}>10{sup 10.7} M{sub sun} ({approx}5 x 10{sup 10} M{sub sun}) red sequence galaxies at 0.066 < z{sub spec} < 0.12 which are smaller than the median size-mass relation by a factor of 2 or more. Consistent with expectations from the virial theorem, the median offset from the mass-velocity dispersion relation for these galaxies is 0.12 dex. We do not, however, find any galaxies with sizes and masses comparable to those observed at z {approx} 2.3, implying a decrease in the comoving number density of these galaxies, at fixed size and mass, by a factor of {approx}>5000. This result cannot be explained by incompleteness: in the 0.066 < z < 0.12 interval, we estimate that the SDSS spectroscopic sample should typically be {approx}>75% complete for galaxies with the sizes and masses seen at high redshift, although for the very smallest galaxies it may be as low as {approx}20%. In order to confirm that the absence of such compact massive galaxies in SDSS is not produced by spectroscopic selection effects, we have also looked for such galaxies in the basic SDSS photometric catalog, using photometric redshifts. While we do find signs of a slight bias against massive, compact galaxies, this analysis suggests that the SDSS spectroscopic sample is missing at most a few objects in the regime we consider. Accepting the high-redshift results, it is clear that massive galaxies must undergo significant structural evolution over z {approx}< 2 in order to match the population seen in the local universe. Our results suggest that a highly stochastic mechanism (e.g., major mergers) cannot be the primary driver of this strong size evolution.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2015

Evidence of incomplete annealing at 800 °C and the effects of 120 °C baking on the crystal orientation and the surface superconducting properties of cold-worked and chemically polished Nb

High-purity niobium rods were cold-worked by wire-drawing, followed by various combinations of chemical polishing and high-vacuum baking at 120 °C or annealing at 800 °C in order to better understand changes to the surface superconducting properties resulting from typical superconducting radio-frequency cavity processing. AC susceptibility measurements revealed an enhanced upper transition T c at ~ 9.3–9.4 K in all samples that was stable through all annealing steps, a value significantly above the accepted T c of 9.23 K for pure annealed niobium. Corresponding elevations were seen in the critical fields, the ratio of the surface critical field H c3 to the bulk upper critical field H c2 rising to 2.3, well above the Ginzburg–Landau value of 1.695. Orientation imaging revealed an extensive dislocation rich sub-grain structure in the as-drawn rods, a small reduction of the surface strain after baking at 120 °C, and a substantial but incomplete recrystallization near the surface after annealing at 800 °C. We interpret these changes in surface superconducting and structural properties to extensive changes in the near-surface interstitial contamination produced by baking and annealing and to synergistic interactions between H and surface O introduced during electropolishing and buffered chemical polishing.

36 MATERIALS SCIENCE↗

DOE OSTI2010

In-medium effects on K{sup 0} mesons in relativistic heavy-ion collisions

We present the transverse momentum spectra and rapidity distributions of {pi}{sup -} and K{sub S}{sup 0} in Ar + KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the High Acceptance Di-Electron Spectrometer (HADES). The reconstructed K{sub S}{sup 0} sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental {pi}{sup -} and K{sub S}{sup 0} distributions to predictions by the Isospin Quantum Molecular Dynamics (IQMD) model. The model calculations show that K{sub S}{sup 0} at low transverse momenta constitute a particularly well-suited tool to investigate the kaon in-medium potential. Our K{sub S}{sup 0} data suggest a strong repulsive in-medium K{sup 0} potential of about 40 MeV strength.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2017

Steps in the Development of Nuclear Thermal Propulsion Fuels

Due to the recent increased interest in Mars and deep-space missions it has been determined to be feasible to revisit the ability for the United States to build a Nuclear Thermal Propulsion (NTP) system. The need to make and qualify a NTP fuel that meets mission performance requirements is an essential first step. Graphite fuels and cermet fuels are of particular interest since these fuels have shown significant advantages over other fuel types. This paper will address the history of NTP fuel fabrication technology as related to the NERVA, GE 710, and Argonne National Laboratory’s Nuclear Fuel Programs as well as recent efforts in recapturing heritage fuels and develop new NTP fuels. Substantial experimental databases and supporting documentation exists for the composite fuel. Some irradiation and high temperature test data is available for cermet fuels, but cermet fuels were never tested at prototypic NTP conditions. A first step in the development effort will be a fuel fabrication recapture effort to provide samples to show that the technology works and performance of the fuel is acceptable. Advances in fuel fabrication, materials processing, and coating technology are expected to improve and/or enhance future fuel development, maturation and certification efforts. The current plan is to perform, non-nuclear separate-effects and integrated tests to provide additional test data and insight into the capabilities of each fuel and to use that data to evaluate potential performance within a NTP engine stage.

Qualls, A↗

DOE OSTI2012

Method for Improving Separation of Carbohydrates from Wood Pulping Liquors and Wood or Biomass Hydrolysis Liquors

Work with industrial partners to perform the studies needed to commercialize U.S. patent 7,699,958 for separation of carbohydrates from wood pulping liquors and wood or biomass hydrolysis liquors. These include: 1) selection of the best pulp mill liquor withdrawal sites, 2) additional purification or enzyme hydrolysis required to obtain acceptable sugar feedstocks, 3) and work with partners to optimize the stream and purification methods to provide acceptable feedstocks for algal fuels and industrial chemicals production, and 4) preparation of samples large enough for testing by downstream partners.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2016

Hard X-ray mirrors for Nuclear Security

Research performed under this LDRD aimed to demonstrate the ability to detect and measure hard X-ray emissions using multilayer X-ray reflective optics above 400 keV, to enable the development of inexpensive and high-accuracy mirror substrates, and to investigate applications of hard X-ray mirrors of interest to the nuclear security community. Experiments conducted at the European Synchrotron Radiation Facility demonstrated hard X-ray mirror reflectivity up to 650 keV for the first time. Hard X-ray optics substrates must have surface roughness under 3 to 4 Angstrom rms, and three materials were evaluated as potential substrates: polycarbonates, thin Schott glass and a new type of flexible glass called Willow Glass®. Chemical smoothing and thermal heating of the surface of polycarbonate samples, which are inexpensive but have poor intrinsic surface characteristics, did not yield acceptable surface roughness. D263 Schott glass was used for the focusing optics of the NASA NuSTAR telescope. The required specialized hardware and process were costly and motivated experiments with a modified non-contact slumping technique. The surface roughness of the glass was preserved and the process yielded cylindrical shells with good net shape pointing to the potential advantage of this technique. Finally, measured surface roughness of 200 and 130 μm thick Willow Glass sheets was between 2 and 2.5 A rms. Additional results of flexibility tests and multilayer deposition campaigns indicated it is a promising substrate for hard X-ray optics. The detection of U and Pu characteristics X-ray lines and gamma emission lines in a high background environment was identified as an area for which X-ray mirrors could have an impact and where focusing optics could help reduce signal to noise ratio by focusing signal onto a smaller detector. Hence the first one twelvetant of a Wolter I focusing optics for the 90 to 140 keV energy range based on aperiodic multilayer coating was designed. Finally, we conducted the first demonstration that reflective multilayer mirrors could be used as diagnostic for HED experiment with an order of magnitude improvement in signal-to-noise ratio for the multilayer optic compared a transmission crystal spectrometer.

36 MATERIALS SCIENCE↗

DOE OSTI2018

X-Ray Diffraction Texture Analysis of Uranium Alloy Fuel PLN-5527 R0

This test plan describes XRD sample characterization for uranium alloys. This test plan includes preferred sample preparation information, characterization method, instrument parameters, calibration method, analysis software, data-acceptance requirements, documentation/reporting requirements. Texture measurements will be taken based on relative peak shapes (e.g., peak height, area, integrated intensity, etc.), relative to the individual XRD pattern.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2022

Destructive Examination of Shipping Package 9975-02731

Destructive and non-destructive examinations were performed on the components of the package 9975-02731 as part of a comprehensive Savannah River Site surveillance program for plutonium materials stored in the K-Area Complex (KAC). The package stored nuclear materials in KAC for 13.8 years. Inspection of the package during opening in KAC noted one non-conforming condition: a large discolored area on the upper fiberboard subassembly. The package was subsequently transferred to Savannah River National Laboratory for more detailed examination. In addition to the observation noted in KAC, the following conditions were observed: (1) Axial gap of 1.021 inch slightly exceeded the 1 inch maximum criterion, and (2) Lead shield height exceeded drawing tolerance of 24.7 inch by 0.019 inch. Visual examination of the upper fiberboard assembly and analysis of the discolored fiberboard indicate the discoloration was due to wood glue residue. The physical, thermal, and mechanical properties of the fiberboard met the acceptance criteria and/or were within the range of previously tested fiberboard and baseline samples. The visual, microscopic and tensile testing results were consistent with previous O-ring and baseline Viton results. The lead shield surface was covered with corrosion product as observed on other shields but there was no evidence of excessive blistering, flaking, or spalling. Besides minor and expected corrosion, no evidence of a degraded condition was found in this package. Examination of the 9975-02731 corroborates existing evidence that the 9975 package is robust and the components can perform their expected functions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗