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At least 307 records · Page 17

Benchmark Exercise Report for Experimental Study of Bubble Scrubbing in Water Coolant Pool

Mechanistic assessments of radionuclide release during postulated accidents are expected to be included in advanced reactor license applications. The mechanistic source term (MST) provides an opportunity for vendors to realistically evaluate the radiological consequences of an incident, and may aid in justifying reduced emergency planning zones and plant sites. However, the development of MSTs for advanced nuclear reactors is challenging because there are numerous phenomena that can affect the transport and retention of radionuclides. As part of a trial MST assessment for a metal-fueled, pool-type sodium cooled fast reactor (SFR), led by Argonne National Laboratory, a simplified radionuclide transport code (SRT code) was developed, which includes models to estimate the quantity of fission product aerosols scrubbed in the sodium pool during postulated accident scenarios. In a pool-type SFR, when fission products are released into the coolant pool due to failure of fuel pins, most of the radionuclides are scrubbed by the coolant pool, but some have the potential to migrate to the cover gas region through entrainment within gas bubbles. The SRT code contains a model that evaluates this scrubbing behavior and calculates the fraction of fission product aerosols that reach the cover gas. Due to a lack of available validation data for sodium pool scrubbing, the U.S. Department of Energy funded an experiment at the University of Wisconsin-Madison to measure aerosol scrubbing by injecting air bubbles containing aerosol into a coolant pool. Prior to performing an experiment with liquid sodium, a water loop experiment was performed. Their experiment evaluated the effect of changing the aerosol size, aerosol density, aerosol concentration, bubble size, and pool depth on the aerosol scrubbing efficiency of the pool. In this benchmark experiment, the base tests were conducted by repeated tests of isolated bubbles. Afterwards, more prototypic tests with bubble swarms were performed to evaluate the interactions between the bubbles. The bubble swarm test was able to confirm that a larger amount of aerosol scrubbing occurred than the single bubble test. It was also confirmed that as the bubble size, aerosol density, and pool height increase, the extent of pool scrubbing also increases and does not change with the aerosol concentration. In addition, since the degree of scrubbing is the lowest at aerosol sizes between 0.01 and 1 μm, that is, the largest amount of aerosol is emitted, it was confirmed that the analysis of this size in MST is the most important. This benchmark experiment informs the direction of future sodium experiments.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

SAGE aerosol measurements. Volume 3: January 1, 1981 to November 18, 1981

The Stratospheric Aerosol and Gas Experiment (SAGE) satellite system, launched February 18, 1979, obtained profiles of aerosol extinction at 1.00 micron and 0.45 micron ozone concentration, and nitrogen dioxide concentration. Data taken during sunset events are presented in the form of zonal and seasonal averages of aerosol extinction of 1.00 micron and 0.45 micron, ratios of aerosol extinction to molecular extinction at 1.00 micron and ratios of aerosol extinction at 0.45 micron to aerosol extinction at 1.00 micron. Averages for 1981 are shown in tables, and in profile and contour plots (as a function of altitude and latitude). In addition, temperature data provided by NOAA for the time and location of each SAGE measurement are averaged and shown in a similar format. The stratospheric aerosol distribution for 1981 shows effects of volcanically injected material from eruptions of Ulawun, Alaid, and Pagan. Peak values of aerosol extinction at 0.45 micron and 1.00 micron were 2 to 4 times higher than typical peak values observed during near background conditions. Stratospheric aerosol optical depth values at 1.00 microns increased by a factor of about 2 from near background levels in regions of volcanic activity. During the year, these values ranged from between 0.001 and 0.006. The largest were near the location of a recent eruption. The distribution of the ratio of aerosol to molecular extinction at 1.00 microns also showed that maximum values are found in the vicinity of an eruption. These maximums varied in altitude, but remained below a height of about 25 km. No attempt has been made to give detailed explanations or interpretations of these data. The intent is to provide, in a ready-to-use visual format, representative zonal and seasonal averages of aerosol extinction data for the third calendar year of the SAGE data set to facilitate atmospheric and climatic studies.

Mccormick, M. Patrick↗

Vegetation Warming Experiment: 15N Uptake Experiment Arctagrostis latifolia Canopy Traits, Utqiagvik (Barrow), Alaska, 2018

This dataset consists of measured Arctagrostis latifolia canopy traits harvested from vegetation warming experiment enclosures and paired control plots located on the BEO, Utqiavik, Alaska. Harvest types include both natural abundance and enriched A. latifolia. Canopy traits measured include leaf area index (LAI), specific leaf area (SLA) and maximum height. Vegetation warming chambers (Zero Power) were deployed on the Barrow Environmental Observatory (BEO), Utqiavik, Alaska. These chambers (Figure 1) consistently elevated air temperatures by approximately 4°C using a self-venting system described by Lewin et al (2017). Five chambers were deployed from June 17, 2018 to September 24, 2018 on the BEO within a 1 km2 area centered on 71.275N, -156.641W. Each chamber was co-located with an ambient plot where temperatures were not manipulated on patches of tundra containing the target species Arctagrostis latifolia. An intensive field campaign in late July investigated the impact of warming had on A. latifolia biomass, chemistry, and uptake of 15N labeled ammonia that was injected into the surface soils for one week. Initial measurements were taken on July 21, 2018. Harvest occurred on July 27, 2018. Water-extractable nutrients in soils were measured in July following harvests of A. latifolia plants and underlying soils. Availability of ammonia, nitrate, and phosphate throughout the growing season was measured by extracting nutrients bound to anion and cation binding resins deployed from July through September. Environmental variables (thaw depth, surface soil temperatures, surface soil moisture) were measured. Leaf traits and root traits of A. latifolia were also measured. This dataset includes one csv file and one pdf file. The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research. The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska. Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗

Effects of swirl and high turbulence on a jet in a crossflow

An experimental study has been conducted on the effects of initial swirl and high turbulence in the exhaust of a circular jet injected from a flat plate at a 90-deg angle into a crossflow. The different jet types studied were low-exit turbulence (3 percent), high-exit turbulence (over 10 percent), and 40 and 58 percent swirl. Surface pressure distributions and mean velocity vector plots were obtained for all of these cases. For the surface pressure distribution tests, the jet to crossflow velocity ratios R were 2.2, 4, and 8 for most of the jet types. For the mean velocity vector plots, R = 4 was chosen. Turbulence information in the jet plume was also obtained for the low-exit turbulence case at R = 4. The results showed that the higher-exit turbulence reduced the penetration height, and it also reduced the surface area influenced by negative pressures. The swirl-caused asymmetric pressure distributions and the swirl effects were more pronounced for lower-velocity ratios.

Kavsaoglu, M. S.↗

SR90, strontium shaped-charge critical ionization velocity experiment

In May 1986 an experiment was performed to test Alfven's critical ionization velocity (CIV) effect in free space, using the first high explosive shaped charge with a conical liner of strontium metal. The release, made at 540 km altitude at dawn twilight, was aimed at 48 deg to B. The background electron density was 1.5 x 10(exp 4) cu cm. A faint field-aligned Sr(+) ion streak with tip velocity of 2.6 km/s was observed from two optical sites. Using two calibration methods, it was calculated that between 4.5 x 10(exp 20) and 2 x 10(exp 21) ions were visible. An ionization time constant of 1920 s was calculated for Sr from the solar UV spectrum and ionization cross section which combined with a computer simulation of the injection predicts 1.7 x 10(exp 21) solar UV ions in the low-velocity part of the ion streak. Thus all the observed ions are from solar UV ionization of the slow (less than critical) velocity portion of the neutral jet. The observed neutral Sr velocity distribution and computer simulations indicate that 2 x 10(exp 21) solar UV ions would have been created from the fast (greater than critical) part of the jet. They would have been more diffuse, and were not observed. Using this fact it was estimated that any CIV ions created were less than 10(exp 21). It was concluded that future Sr CIV free space experiments should be conducted below the UV shadow height and in much larger background plasma density.

Wescott, Eugene M.↗

The 1992/93 eclipse of 31 Cygni

Extensive new ultraviolet and optical spectra of an atmospheric eclipse define the physical properties throughout the wind and chromosphere of 31 Cyg. These data require mass loss of approximately 3 x 10(exp -8) solar masses/yr in a wind that may merge smoothly into the chromosphere. Considerations of how energy is injected into the wind, however, suggest that the chromosphere and wind are separate structures. Most, if not all, of the velocity structure in metallic lines, which we have heretofore simulated with Doppler widths in the range 15-25 km/s, results from differential expansion of the atmosphere. Electron densities in the inner R(sub star) of the chromosphere are in the range 1.5 x 10(exp 9) - 2 x 10(exp 8)/cu cm, which implies clumping of the gas. The ionization of oxygen and nitrogen is consistent with clumping by factors of 3-30 in the outer chromosphere, roughly the amount required to give enough gas pressure to support the chromosphere. Chromospheric gas in 31 Cyg becomes hotter with increasing height, thus with decreasing optical depth, in a way that seems similar for all the zeta Aur binaries. Excitation temperature for Fe II in 1992/93 rises from about 5000 K at the deepest points sampled to about 12,500 K high in the wind. Strengths of violet Balmer lines give an excitation temperature for hydrogen of 6200-6500 K above a radial mass column density of approximately 0.01 g/sq cm. This amount of excitation implies that Lyman-alpha is thermalized beneath about 4 x 10(exp -3) g/sq cm. The outer atmosphere was symmetrical to within a factor of 2 in 1992/93, although it was clearly variable at this level, and it had similar mass column densities as in 1982. One manifestation of the variability was a flow toward the B star at phases 0.013-0.022 spanning velocities 45-100 km/s. Several lines of evidence point to a complicated and variable ionization in the wind: At large distance from the K star, measured mass column densities are less by up to a factor of 3 than required by a smoothly flowing wind. Also, much of the gas beyond r = 350 solar radii = 1.75 R(sub star) has a negative radial velocity. Radial velocities of the shell lines imply the outer atmosphere rotates in the direction of orbital motion, possibly through the deflection of wind flow lines in this direction.

Eaton, Joel A.↗

From Well Log to Formation Model: A Novel Laboratory Calibrated Methodology with Demonstration

This work demonstrates how the characterization and modeling of both elastic and creep properties are essential to describe zones in layered rock formations as either low-stress targets for stimulation or high-stress barriers to fracture growth. Prediction of fracture height is critical for designing stimulation operations in oil and gas wells. Ideally, fractures are placed in target zones which will produce hydrocarbons and should not propagate into zones expected to be unproductive or to produce unwanted fluids such as water which in turn must be treated and/or disposed. The essential task in designing stimulation plans is predicting which zones have low horizontal stresses and which will be high-stress barriers to fracture growth. Despite this importance, there are gaps in current knowledge and a complete workflow from laboratory characterization to a finite element model which includes time dependent rock deformation is required. While the research and methodology presented here also have application to CO 2or hydrogen storage, wastewater injection, and geothermal applications, the focus will be on hydrocarbon extraction. This thesis presents the results of a characterization-to-prediction workflow for the Caney shale, which is an emerging hydrocarbon resource in Oklahoma, USA. It begins with an investigation to enable critical evaluation of the Caney zonation into nominally “brittle” and “ductile” zones based on properties observed from well logs. It shows none of the zones are consistently “brittle” or “ductile” mechanical behavior based on the variety of definitions of these terms. However, the nominally ductile zones are weaker and more prone to creep. A laboratory investigation of samples including strength, elastic, and creep properties, is then used in a finite element model of stress evolution. The model includes both elastic deformation and viscoplastic creep. Results predict the least creep-prone layers to have the lowest horizontal stresses, therefore comprising hydraulic fracturing targets. The most creep-prone layers attain a horizontal stress similar to the vertical stress and therefore are predicted to be high stress barriers to hydraulic fracture stimulation. In addition to defining stimulation target intervals, the model shows how as tectonic strain rate increases, there is a transition from creep-dominated stresses to stresses dominated by elasticity.

Benge, Margaret↗

Heavy ions from the Galilean satellites and the centrifugal distortion of the Jovian magnetosphere

The Galilean satellites constitute a potentially significant source of plasma to the Jovian atmosphere. The paper examines the distortion of the Jovian magnetosphere that would result from injection of ions at the Galilean satellites. The magnetic distortion produced is a localized perturbation near the equatorial plane, in contrast to the large-scale distortion produced by Jovian atmospheric ions. The study estimates the relative perturbation currents resulting from the two sources in terms of the unknown ion production rate at the satellites. It is found that the two perturbations would be of comparable magnitudes if the ion source flux at all of the Galilean satellites were comparable to the photo-ion escape flux from Jupiter's atmosphere. More specifically, ions produced by the Galilean satellites should be confined near the equatorial plane of Jupiter's magnetosphere in a sheet whose thickness is determined by a centrifugal scale height given essentially by the ion thermal speed divided by the corotation frequency.

Hill, T. W.↗

A novel Whole Air Sample Profiler (WASP) for the quantification of volatile organic compounds in the boundary layer

The emission and fate of reactive VOCs is of inherent interest to those studying chemical biosphere-atmosphere interactions. In-canopy VOC observations are obtainable using tower-based samplers, but the lack of suitable sampling systems for the full boundary 5 layer has limited the data characterizing the vertical structure of such gases above the canopy height and still in the boundary layer. This is the important region where many reactive VOCs are oxidized or otherwise removed. Here we describe an airborne sampling system designed to collect a vertical profile of air into a 3/800 OD tube 150m in length. The inlet ram air pressure is used to flow sampled air through the 10 tube, which results in a varying flow rate based on aircraft speed and altitude. Since aircraft velocity decreases during ascent, it is necessary to account for the variable flow rate into the tube. This is accomplished using a reference gas that is pulsed into the air stream so that the precise altitude of the collected air can be reconstructed post-collection. The pulsed injections are also used to determine any significant effect 15 from diffusion/mixing within the sampling tube, either during collection or subsequent extraction for gas analysis. This system has been successfully deployed, and we show some measured vertical profiles of isoprene and its oxidation products methacrolein and methyl vinyl ketone from a mixed canopy near Columbia, Missouri.

Mak, J. E.↗

SOLAR HARD X-RAY SOURCE SIZES IN A BEAM-HEATED AND IONIZED CHROMOSPHERE

Solar flare hard X-rays (HXRs) are produced as bremsstrahlung when an accelerated population of electrons interacts with the dense chromospheric plasma. HXR observations presented by Kontar et al. using the Ramaty High-Energy Solar Spectroscopic Imager have shown that HXR source sizes are three to six times more extended in height than those predicted by the standard collisional thick target model (CTTM). Several possible explanations have been put forward including the multi-threaded nature of flare loops, pitch-angle scattering, and magnetic mirroring. However, the nonuniform ionization (NUI) structure along the path of the electron beam has not been fully explored as a solution to this problem. Ionized plasma is known to be less effective at producing nonthermal bremsstrahlung HXRs when compared to neutral plasma. If the peak HXR emission was produced in a locally ionized region within the chromosphere, the intensity of emission will be preferentially reduced around this peak, resulting in a more extended source. Due to this effect, along with the associated density enhancement in the upper chromosphere, injection of a beam of electrons into a partially ionized plasma should result in an HXR source that is substantially more vertically extended relative to that for a neutral target. Here we present the results of a modification to the CTTM, which takes into account both a localized form of chromospheric NUI and an increased target density. We find 50 keV HXR source widths, with and without the inclusion of a locally ionized region, of ∼3 Mm and ∼0.7 Mm, respectively. This helps to provide a theoretical solution to the currently open question of overly extended HXR sources.

79 ASTRONOMY AND ASTROPHYSICS↗

Effects of diffusion and mass flows on C IV and Si IV lines formed in the solar atmosphere

A model for the transition region is derived from an initial interpretation of EUV observations, assuming ionization equilibrium and constant elemental abundance with height. The effects of diffusion and mass flows are then included in the initial model and the emergent profiles of several C IV and Si IV lines are computed. It is found that diffusion and mass flows have a strong effect on both the emergent intensity and spectral shape of these lines. Diffusion acts to deplete the transition region of heavy ions to an extent which depends on the detailed temperature and density structure. The net effect is a weighting of the coronal emission relative to that in the transition. On the basis of the results, it is suggested that the downflows observed in the network in lines of C IV and Si IV could be due to gravitational settling of the ions following their injection, via diffusion, into the corona from spicules. When flows are superposed on the basic diffusion model, the rapid change in elemental abundance characteristic of the model is virtually eliminated and the coronal contribution to the emission in C IV and Si IV lines becomes negligible relative to that in the transition region. Flows have a strong effect on the computed line intensities and introduce large asymmetries into the line shapes.

Roussel-Dupre, R.↗

Effect of volcanic debris on stratospheric ion conductivity

The reduction is reported of stratospheric ion conductivities in the altitude range of 20 to 27 km attributable to the aerosols injected into the stratosphere by the eruption of volcano Nevado Del Ruiz on November 13, 1985. Three balloon experiments were conducted from Hyderabad, India (17.5 N, 78.6 E) carrying a Langmuir probe payload for measuring stratospheric ion conductivities. The first flight took place about 9 months before the volcanic eruption, the second 3 weeks after the eruption and the third about a year later. Lidar observations from Japan, Hawaii and Europe reported detection of aerosol layers in the 18 to 25 km altitude range attributable to the Nevado Del Ruiz volcanic eruption. A comparison of the conductivity profiles shows that the reduction of ion conductivities is: 57.3 percent at 20 km and 31 percent at 25 km. A year after the eruption, conductivities at all heights tended to recover.

Somayajulu, Y. V.↗

Vegetation Warming Experiment: 15N Uptake Experiment Environmental Observations and Thaw Depth, Utqiagvik (Barrow), Alaska, 2018

This dataset consists of measured soil thaw depth, soil temperature, soil moisture, and Arctagrostis latifolia height in vegetation warming experiment enclosures and paired control plots. Vegetation warming chambers (Zero Power) were deployed on the Barrow Environmental Observatory (BEO), Utqiagvik, Alaska. These chambers (Figure 1) consistently elevated air temperatures by approximately 4°C using a self-venting system described by Lewin et al (2017). Five chambers were deployed from June 17, 2018 to September 24, 2018 on the BEO within a 1 km2 area centered on 71.275N, -156.641W. Each chamber was co-located with an ambient plot where temperatures were not manipulated on patches of tundra containing the target species Arctagrostis latifolia. An intensive field campaign in late July investigated the impact of warming had on A. latifolia biomass, chemistry, and uptake of 15N labeled ammonia that was injected into the surface soils for one week. Initial measurements were taken on July 21, 2018. Harvest occurred on July 27, 2018. Water-extractable nutrients in soils were measured in July following harvests of A. latifolia plants and underlying soils. Availability of ammonia, nitrate, and phosphate throughout the growing season was measured by extracting nutrients bound to anion and cation binding resins deployed from July through September. Environmental variables (thaw depth, surface soil temperatures, surface soil moisture) were measured. Leaf traits and root traits of A. latifolia were also measured. Included are two *.csv data files and one *.pdf user guide. The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research. The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska. Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗

Plasma impurities observed by a pulse height analysis diagnostic during the divertor campaign of the Wendelstein 7-X stellarator

The paper reports on the optimization process of the soft X-ray pulse height analyzer installed on the Wendelstein 7-X (W7-X) stellarator. It is a 3-channel system that records X-ray spectra in the range from 0.6 to 19.6 keV. X-ray spectra, with a temporal and spatial resolution of 100 ms and 2.5 cm (depending on selected slit sizes), respectively, are line integrated along a line-of-sight that crosses near to the plasma center. In the second W7-X operation phase with a carbon test divertor unit, we report light impurities, e.g., carbon and oxygen, were observed as well as mid- to high-Z elements, e.g., sulfur, chlorine, chromium, manganese, iron, and nickel. In addition, X-ray lines from several tracer elements have been observed after the laser blow-off injection of different impurities, e.g., silicon, titanium, and iron, and during discharges with prefill or a gas puff of neon or argon. These measurements were achieved by optimizing light absorber-foil selection, which defines the detected energy range, and remotely controlled pinhole size, which defines photon flux. The identification of X-ray lines was confirmed by other spectroscopic diagnostics, e.g., by the High-Efficiency XUV Overview Spectrometer, HEXOS, and high-resolution X-ray imaging spectrometer, HR-XIS.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Numerical modeling of the interstellar medium in galactic disks

We have been developing detailed hydrodynamic models of the global interstellar medium in the hope of understanding the mass and volume occupied by various phases, as well as their structure and kinematics. In our model, the gas is modeled by one fluid while representative Pop 1 stars are modeled by a second fluid. The two fluids are coupled in that the gas forms into stars at a rate given by a Schmidt law while stellar mass loss returns matter into the gas phase (on a time scale of 100 Myr). Also, the stars heat the gas through stellar winds and the gas cools through optically thin radiation. The time behavior of these two fluids is studied in two spatial dimensions with the Eulerian finite difference numerical hydrodynamic code Zen. The two spatial dimensions are along the plane of a disk (x, total length of 2 kpc) and perpendicular to the disk (z, total height of +/- 15 kpc) and a galactic gravitational field in the z direction, typical of that at the solar circle, is imposed upon the simulation; self-gravity and rotation are absent. For the boundary conditions, outflow is permitted at the top and bottom of the grid (z = +/- 15 kpc) while periodic boundary conditions are imposed upon left and right sides of the grid. As initial conditions, we assumed a gaseous distribution like that seen for the H1 by earlier researchers, although the results are insensitive to the initial conditions. We have run simulations in which the heating due to stars, parameterized as a stellar wind velocity, a, is varied from low (a = 150 km/s), to intermediate (a = 300 km/s), to high (a = 600 km/s). Since the intermediate case is roughly equivalent to the Galactic energy injection rate from supernovae, this summary will concentrate on results from this simulation.

Rosen, A.↗

Separation and Detection of Toxic Gases with a Silicon Micromachined Gas Chromatography System

A miniature gas chromatography (GC) system was designed and fabricated using silicon micromachining and integrated circuit (IC) processing techniques. The silicon micromachined gas chromatography system (SMGCS) is composed of a miniature sample injector that incorporates a 10 microliter sample loop; a 0.9 meter long, rectangular shaped (300 micrometer width and 10 micrometer height) capillary column coated with a 0.2 micrometer thick copper phthalocyanine (CuPc) stationary phase; and a dual detector scheme based upon a CuPc-coated chemiresistor and a commercially available 125 micrometer diameter thermal conductivity detector (TCD) bead. Silicon micromachining was employed to fabricate the interface between the sample injector and the GC column, the column itself, and the dual detector cavity. A novel IC thin-film processing technique was developed to sublime the CuPc stationary phase coating on the column walls that were micromachined in the host silicon wafer substrate and Pyrex (r) cover plate, which were then electrostatically bonded together. The SMGCS can separate binary gas mixtures composed of parts-per-million (ppm) concentrations of ammonia (NH3) and nitrogen dioxide (NO2) when isothermally operated (55-80 degrees C). With a helium carrier gas and nitrogen diluent, a 10 microliter sample volume containing ammonia and nitrogen dioxide injected at 40 psi ((2.8 x 10(exp 5)Pa)) can be separated in less than 30 minutes.

Kolesar, Edward S.↗

Overview of the COMPASS results *

COMPASS addressed several physical processes that may explain the behaviour of important phenomena. This paper presents results related to the main fields of COMPASS research obtained in the recent two years, including studies of turbulence, L–H transition, plasma material interaction, runaway electron, and disruption physics: Tomographic reconstruction of the edge/SOL turbulence observed by a fast visible camera allowed to visualize turbulent structures without perturbing the plasma. Dependence of the power threshold on the X-point height was studied and related role of radial electric field in the edge/SOL plasma was identified. The effect of high-field-side error fields on the L–H transition was investigated in order to assess the influence of the central solenoid misalignment and the possibility to compensate these error fields by low-field-side coils. Results of fast measurements of electron temperature during ELMs show the ELM peak values at the divertor are around 80% of the initial temperature at the pedestal. Liquid metals were used for the first time as plasma facing material in ELMy H-mode in the tokamak divertor. Good power handling capability was observed for heat fluxes up to 12 MW m –2 and no direct droplet ejection was observed. Partial detachment regime was achieved by impurity seeding in the divertor. The evolution of the heat flux footprint at the outer target was studied. Runaway electrons were studied using new unique systems—impact calorimetry, carbon pellet injection technique, wide variety of magnetic perturbations. Radial feedback control was imposed on the beam. Forces during plasma disruptions were monitored by a number of new diagnostics for vacuum vessel (VV) motion in order to contribute to the scaling laws of sideways disruption forces for ITER. Current flows towards the divertor tiles, incl. possible short-circuiting through PFCs, were investigated during the VDE experiments. The results support ATEC model and improve understanding of disruption loads.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

The Cypress Sandstone Seal System

The Cypress Sandstone is the youngest and shallowest unit in the Illinois Basin that was featured in the United States Carbon Utilization and Storage Atlas IV as a target for saline carbon storage with an estimated 0.2 to 2.3 GT of storage potential. Additional research on a residual oil zone (ROZ) developed within the Cypress Sandstone has delineated 27 prospects with approximately 290.8 million m3 (1.8 billion barrels) of oil in place. 21 to 31 million m 3 (144 to 196 million barrels) of oil is estimated to be recoverable using carbon dioxide enhanced oil recovery (CO 2 -EOR). Storage of CO 2 associated with EOR in these ROZ prospects alone, not accounting for associated main pay zones (MPZs), underlying brine formation, or intervals adjacent to or between prospects, is estimated to be up to 10.4 billion tonnes. The Cypress Sandstone is thus well understood to be a CO 2 injection target, both for EOR and associated storage. However, the seal system overlying the Cypress Sandstone is poorly understood. Unlike deeper formations such as the Mt. Simon Sandstone or the St. Peter Sandstone which are either in use as a CO 2 sink or being characterized for prospective storage, respectively, the Cypress is not overlain by hundreds of feet of impermeable shale. Rather, the Cypress is overlain by a lithologically variable interval that is composed generally of shales and limestones with some sandstone in the part of the Basin where the Cypress is deep enough to facilitate CO 2 storage. Also, due to its status as one of the shallowest and most prolific oil reservoirs in the Basin, the seal system overlying the Cypress Sandstone has a relatively high number of legacy well penetrations. The purpose of this report is to characterize the Cypress Sandstone seal system using well logs and available core. Gross thickness, lithology (facies), and mineralogy of seals is described and mapped across the Basin. The column height of CO 2 that can be held is calculated using capillary pressure data from a representative core.

02 PETROLEUM↗