Zeolites and Metal Organic Frameworks for Noble Gas Separation
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Demers, Steven [Savannah River National Laboratory↗
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Regularizing the linearly extrapolated BDF2 scheme for incompressible flows with time relaxation
This paper presents a highly-efficient finite element scheme for the time relaxation model (TRM). The efficiency is achieved through the second-order BDF2 time-stepping scheme with linear extrapolation (BDF2LE). The accuracy of the scheme is also greatly enhanced through the use of the divergence-free Scott-Vogeulis finite elements, and van Cittert approximate deconvolution. A complete finite element analysis is provided, which includes rigorous proofs for the stability, well-possessedness, and convergence of both velocity and pressure solutions. Furthermore, we also demonstrate that the inclusion of the linear time relaxation term preserves the long-time stability of the unregularized BDF2LE scheme. Finally, numerical experiments are presented that demonstrate the added stability and accuracy that time relaxation can provide.
97 MATHEMATICS AND COMPUTING↗
Overview of oxygen opacity experiments at the National Ignition Facility and investigation of potential systematic errors
Experiments to measure oxygen opacity at stellar interior conditions have been performed at the National Ignition Facility in a Discovery Science campaign. These experiments utilize the Opacity-on-NIF platform with a sample comprised of O, Mg, and Si. The spectral data from the Opacity Spectrometer cover the 1000–2000 eV photon energy range showing bound-free continuum absorption from O and line absorption from Mg and Si. DANTE and the Gated X-ray Detector are employed to measure the sample plasma’s temperature and density, respectively. Initial data show lower transmission than expected by theoretical models, raising questions of whether potential background or data uniformity concerns could produce systematic errors in the inferred transmission. Here, we investigate three concerns thought to be important for the oxygen opacity data, including instrumental scattered background, sample self-emission non-uniformity, and backlight continuum non-uniformity. Additionally, we show the effect of a recently developed method to account for 2nd order crystal reflection. The total effect of these concerns on one experiment is found to be small compared to the observed difference between the inferred transmission and a model calculation at the inferred temperature and density. Thus, we conclude that these potential sources of systematic error cannot account for the observed difference, increasing the likelihood of a real effect due to the high temperature and density conditions. However, because this is only a single experiment, we cannot make a firm conclusion. More experiments measuring the opacity and necessary calibrations are needed to assess the reproducibility and uncertainty of this result.
79 ASTRONOMY AND ASTROPHYSICS↗
Detecting 127 Xe in an atmospheric tracer experiment
The Xcounts algorithm for calculating air concentrations of radioactive xenon isotopes (Eslinger et al., 2023) has been extended to estimate 127 Xe in addition to 131m Xe, 133m Xe, 133 Xe, and 135 Xe. The algorithm was applied to 119 samples collected with a SAUNA Q B system (Ringbom et al., 2023) during a two-month atmospheric tracer release experiment. Finally, the algorithm identified two samples with 127 Xe present from a single 1.5 h release about 3.5 km upwind of the sampler and no false detections of 127 Xe were observed in the other samples.
127Xe calibration↗
Inferring fusion nuclear burnwidths with low gain photomultiplier impulse response functions
When an inertial confinement fusion implosion is compressed, it maintains thermonuclear density and temperatures for a very short time scale, about 100 ps. The Gamma Reaction History diagnostic measures the time evolution of the fusion burn, but its temporal resolution is limited by the use of a photomultiplier tube (PMT) to amplify the photon signal. Multichannel plate-based PMTs have a fast (~120 ps) full-width at half-max impulse response function (IRF), but the time scale is similar to the incoming physics signal. An analysis routine is used to remove the effect of the PMT IRF and infer the incident fusion burnwidth. With the National Ignition Facility achieving ignition and creating much brighter signals, the PMTs are run at gains three orders of magnitude lower than nominal operation. Calibration at these settings shows the PMT IRFs get ~15% wider. Taking the gain-dependent IRF can affect the inferred nuclear burnwidths by up to ~15%.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Experimental shock Hugoniot and melt boundary temperatures of aluminum
Aluminum is a ubiquitous component in dynamic compression, pulsed power, and other high energy density physics studies. Its high-pressure behavior and phase diagram are extensively studied standards in shockwave physics. While theoretical calculations and multiphase equations of state have been benchmarked to velocity measurements of loading and unloading waves, pressure and density under shock, and other mechanical data, experimental temperature data under these conditions have not been reported. We conducted a series of experiments shocking and releasing aluminum 6061 and 1100 samples into lithium fluoride windows. We measured temperature at the sample–window interface under steady compression and subsequent isentropic release. These results allow us to constrain the temperature of the solid Hugoniot and the boundary between the liquid and face-centered cubic solid phases.
Hartsfield, Thomas Murray [Sandia National Laborat↗
Seismoacoustic background noise variations and state of health assessment across a geographically diverse sensor network in Nevada
AGU 2024 poster
Malach, Amrit Kaur [Sandia National Laboratories (↗
Compression behavior of lithium fluoride up to 80 GPa and 2300 K
Here, the high-temperature compression behavior of lithium fluoride (LiF) has been determined to ∼80 GPa and 2300 K by means of high-resolution synchrotron-based x-ray diffraction in a laser-heated diamond-anvil cell. The room-temperature Vinet equation of state (EOS) for LiF yields an isothermal room-temperature, ambient-pressure lattice parameter a 0 = 4.028 (±0.003) Å, volume V 0 = 65.35 (±0.03) Å 3 , bulk modulus K 0 = 67.57 (±0.34) GPa, and its pressure derivative K 0 ’ = 4.64 (±0.03). This expanded experimental dataset is in good agreement with the LiF thermal equation of state by Myint et al. (2019) up to ∼2300 K and 25 GPa. At higher pressures and temperatures our data shows reduced thermal expansion compared to the prediction and may be particularly important for experiments at more extreme conditions.
High-pressure behavior↗
Energy response characterization of current-mode MeV Cherenkov aerogel detectors
Current-mode Cherenkov aerogel detectors have been used to measure time resolved spectra of MeV radiographic x-ray sources and have been considered to replace gas Cherenkov systems. The simulations of the Cherenkov response of aerogel detectors have uncertainties in how to model the complex structure of aerogels. Data from three sites—the Idaho electron beam, the Los Alamos Site electron beam and microtron sources at Los Alamos—have been used to calibrate the relative energy response of 15 aerogels, varying in density from 10 to 430 mg/cm 3 , from incident electrons with energies from 1 to 12 MeV. Detector simulations need to introduce density variation in the aerogels to match the collected data.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Real-Time, Adaptive Radiological Anomaly Detection and Isotope Identification Using Non-Negative Matrix Factorization
Spectroscopic anomaly detection and isotope identification algorithms are integral components in nuclear nonproliferation applications such as search operations. The task is especially challenging in the case of mobile detector systems because the observed gamma-ray background changes more than for a static detector system, and a pretrained background model can easily find itself out of domain. The result is that algorithms may exceed their intended false alarm rate or sacrifice detection sensitivity to maintain the desired false alarm rate. Non-negative matrix factorization (NMF) is a powerful tool for spectral anomaly detection and identification, but, like many similar algorithms that rely on data-driven background models, in its conventional implementation, it is unable to update in real time to account for environmental changes that affect the background spectroscopic signature. Here, we have developed a novel NMF-based algorithm that periodically updates its background model to accommodate changing environmental conditions. The adaptive NMF algorithm involves fewer assumptions about its environment, making it more generalizable than existing NMF-based methods while maintaining or exceeding detection performance on simulated and real-world datasets.
Anomaly detection↗
Post-Closure Report for Closed Resource Conservation and Recovery Act Corrective Action Units, Nevada National Security Site, Nevada
This report covers fiscal year 2012 (October 2011–September 2012). The post-closure requirements for these sites are described in Resource Conservation and Recovery Act Permit Number NEV HW0101 and summarized in each CAU-specific section in Section 1.0 of this report. The results of the inspections, a summary of maintenance activities, and an evaluation of monitoring data are presented in this report.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Nevada National Security Site 2012 Data Report: Groundwater Monitoring Program Area 5 Radioactive Waste Management Site
This report is a compilation of the groundwater sampling results from the Area 5 Radioactive Waste Management Site (RWMS). The data have been collected since 1993 and include calendar year 2012 results. During 2012, groundwater samples were collected and static water levels were measured at the three pilot wells surrounding the Area 5 RWMS. Groundwater samples were collected at UE5PW-1, UE5PW-2, and UE5PW-3 on March 21, August 7, August 21, and September 11, 2012, and static water levels were measured at each of the three pilot wells on March 19, June 6, August 2, and October 15, 2012. Groundwater samples were analyzed for the following indicators of contamination: pH, specific conductance, total organic carbon, total organic halides, and tritium. Indicators of general water chemistry (cations and anions) were also measured. Final results from samples collected in 2012 were within the limits established by agreement with the Nevada Division of Environmental Protection for each analyte. These data indicate that there has been no measurable impact to the uppermost aquifer from the Area 5 RWMS. There were no significant changes in measured groundwater parameters compared to previous years. The report contains an updated cumulative chronology for the Area 5 RWMS Groundwater Monitoring Program and a brief description of the site hydrogeology.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Completion Report for Well ER-20-11, Corrective Action Units 101 and 102: Central and Western Pahute Mesa
Well ER-20-11 was drilled for the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office in support of the Nevada Environmental Management Operations Underground Test Area (UGTA) Activity at the Nevada National Security Site (formerly Nevada Test Site), Nye County, Nevada. The well was drilled in September 2012 as part of the Central and Western Pahute Mesa Corrective Action Unit Phase II drilling program. Well ER-20-11 was constructed to further investigate the nature and extent of radionuclide-contaminated groundwater encountered in two nearby UGTA wells, to help define hydraulic and transport parameters for the contaminated Benham aquifer, and to provide data for the UGTA hydrostratigraphic framework model. The 44.5-centimeter (cm) surface hole was drilled to a depth of 520.0 meters (m) and cased with 34.0-cm casing to 511.5 m. The hole diameter was then decreased to 31.1 cm, and the borehole was drilled to a total depth of 915.6 m. The hole was completed to allow access for hydrologic testing and sampling in the target aquifer, which is a lava-flow aquifer known as the Benham aquifer. The completion casing string, set to the depth of 904.3 m, consists of a string of 6 5/8-inch (in.) stainless-steel casing hanging from a string of 7 5/8-in. carbon-steel casing. The stainless-steel casing has one slotted interval at 796.3 to 903.6 m. One piezometer string was installed, which consists of 2 7/8-in. stainless-steel tubing that hangs from 2 3/8-in. carbon-steel tubing via a crossover sub. This string was landed at 903.8 m and is slotted in the interval 795.3 to 903.1 m. Data collected during and shortly after hole construction include composite drill cuttings samples collected every 3.0 m, various geophysical logs, fluid samples (for groundwater chemistry analysis and tritium measurements), and water-level measurements. The well penetrated 915.6 m of Tertiary volcanic rock, including one saturated lava flow aquifer. Measurements on samples taken from the undeveloped well indicated elevated tritium levels within the Benham aquifer. The maximum tritium level measured with field equipment was 146,131 picocuries per liter from a sample obtained at the depth of 912.0 m. The fluid level was measured in the piezometer string at a depth of 504.5 m on September 26, 2012. All Fluid Management Plan (FMP) requirements for Well ER-20-11 were met. Analysis of monitoring samples and FMP confirmatory samples indicated that fluids generated during drilling at Well ER-20-11 met the FMP criteria for discharge to an unlined sump or designated infiltration area. Well development, hydrologic testing, and sampling will be conducted at a later date.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
RCRA Permit for a Hazardous Waste Management Facility Permit Number NEV HW0101 Annual Summary/Waste Minimization Report Calendar Year 2012, Nevada National Security Site, Nevada
This report summarizes the U.S. Environmental Protection Agency (EPA) identification number of each generator from which the Permittee received a waste stream, a description and quantity of each waste stream in tons and cubic feet received at the facility, the method of treatment, storage, and/or disposal for each waste stream, a description of the waste minimization efforts undertaken, a description of the changes in volume and toxicity of waste actually received, any unusual occurrences, and the results of tank integrity assessments. This Annual Summary/Waste Minimization Report is prepared in accordance with Section 2.13.3 of Permit Number NEV HW0101, issued 10/17/10.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Nevada National Security Site Environmental Report 2012 Summary
This document is a summary of the full Nevada National Security Site Environmental Report 2012.
54 ENVIRONMENTAL SCIENCES↗
Post-Closure Inspection Letter Report for Corrective Action Units on the Nevada National Security Site: Calendar Year 2013
This letter serves as the post-closure inspection letter report for Corrective Action Units (CAUs) on the Nevada National Security Site for calendar year 2013. The inspections identified maintenance and repair is required at the following sites: sign and/or fence repair is necessary at CAUs 113, 137, 139, 140, 143, 262, 370, 371, 372, 374, 476, 478, 529, 542, and 560; animal burrows were identified at CAU 547; and erosion was identified at CAUs 366, 367, 383, 551, and 574. In addition, the following use restrictions were removed during 2013 and will no longer be inspected in 2014: 165, 357, and 528.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Interim Activities at Corrective Action Unit 114: Area 25 EMAD Facility, Nevada National Security Site, Nevada, for Fiscal Years 2012 and 2013
This letter report documents interim activities that have been completed at CAU 114 in fiscal years 2012 and 2013.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Nevada National Security Site Environmental Report 2013
This report was prepared to meet the information needs of the public and the requirements and guidelines of the U.S. Department of Energy (DOE) for annual site environmental reports. It was prepared by National Security Technologies, LLC (NSTec), for the U.S. Department of Energy, National Nuclear Security Administration Nevada Field Office (NNSA/NFO) (formerly designated as the Nevada Site Office [NNSA/NSO]). The new field office designation occurred in March 2013. Published reports cited in this 2013 report, therefore, may bear the name or authorship of NNSA/NSO. This and previous years’ reports, called Annual Site Environmental Reports (ASERs), Nevada Test Site Environmental Reports (NTSERs), and, beginning in 2010, Nevada National Security Site Environmental Reports (NNSSERs), are posted on the NNSA/NFO website at http://www.nv.energy.gov/library/publications/aser.aspx.
54 ENVIRONMENTAL SCIENCES↗