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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.

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At least 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

The properties and fate of the galactic center G2 cloud

The object G2 was recently discovered descending into the gravitational potential of the supermassive black hole (BH) Sgr A*. We test the photoionized cloud scenario, determine the cloud properties, and estimate the emission during the pericenter passage. The incident radiation is computed starting from the individual stars at the locations of G2. The radiative transfer calculations are conducted with CLOUDY code and 2011 broadband and line luminosities are fitted. The spherically symmetric, tidally distorted, and magnetically arrested cloud shapes are tested with both the interstellar medium dust and 10 nm graphite dust. The best-fitting magnetically arrested model has the initial density n {sub init} = 1.8 × 10{sup 5} cm{sup –3}, initial radius R {sub init} = 2.2 × 10{sup 15} cm = 17 mas, mass m {sub cloud} = 4 M {sub Earth}, and dust relative abundance A = 0.072. It provides a good fit to 2011 data, is consistent with the luminosities in 2004 and 2008, and reaches an agreement with the observed size. We revise down the predicted radio and X-ray bow shock luminosities to be below the quiescent level of Sgr A*, which readily leads to non-detection in agreement to observations. The magnetic energy dissipation in the cloud at the pericenter coupled with more powerful irradiation may lead to an infrared source with an apparent magnitude m{sub L{sup ′}}≈13.0. No shock into the cloud and no X-rays are expected from cloud squeezing by the ambient gas pressure. Larger than previously estimated cloud mass m {sub cloud} = (4-20) M {sub Earth} may produce a higher accretion rate and a brighter state of Sgr A* as the debris descend onto the BH.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Use of Hygrothermal Models for Understanding Water Transport in Corrosion Under Insulation Applications

Thermal insulation is used in operating facilities to conserve heat and protect against freezing amongst others. A consequence of insulating the equipment is the necessity to manage the introduced threat of corrosion under insulation (CUI). For CUI to occur, water and oxygen must enter and migrate through the insulation to reach the external surface of the equipment. The water transport characteristics are dependent on several factors such as type of insulation, type of jacketing, equipment operating temperature, external weather, water entry/leakage rate and cyclic service. In hot piping, there are competing water transport characteristics, as in water vapor moves outwards away from the equipment as water enters insulation. Knowing the water transport and the parameters that influence the time of wetness at the metal surface helps in understanding conditions favoring CUI.The use of transient hygrothermal models for moisture control is well established in the building insulation design codes and standards. The building designs naturally shed the liquid water to minimize entry and facilitate vapor management so that moisture doesn’t accumulate within building. Several building industry hygrothermal models have been developed and are available for commercial use. One such commercial model has been used to understand water transport in a CUI application. The case study involves evaluation of piping and equipment installed with a closed cell polyurethane insulation. The hygrothermal model provided insights on the parameters influencing the time of wetness and the ease of water escaping the equipment-insulation-jacketing system.

Venkateswaran, Sai P.↗
DOE OSTI2013

Modeling of plasma processes in the slowly diverging magnetic fields at the exit of an applied-field magnetoplasmadynamic thruster

The performance of plasma thrusters with applied electric and magnetic fields can be enhanced by increasing the magnetic field strength, which is applied in the thrust chamber and the exit region propulsive plume. The ejected plasma which passes through a slowly diverging magnetic field will expand but can be restricted within the magnetic nozzle fields. To examine in detail the processes that occur, a new method with Particle-in-cell calculations is applied here. A two-dimensional axisymmetric particle dynamic code is used to model an AF-MPDT (Applied-field Magnetoplasmadynamic Thruster) for which extensive experimental data are available; it used Ar propellant and had applied magnetic coils of 101.5 mm radius and 153 mm length. From the results of the simulation study, it is found that total thrust increases linearly with magnetic field strength in the range of 0–0.1 T, but it decreases with increasing applied magnetic field up to 0.6 T. Thrust efficiency is found to increase to a maximum of 8.4% when B = 0.1 T; further, the peak value of nozzle efficiency reaches 91% at a moderate magnetic field (0.3 T). In detail, it is found that distributions of plasma density (10{sup 14}–10{sup 15} m{sup −3}) that form in the magnetic nozzle demonstrate a significant pattern of concentration up to fields of B = 0.3 T where ions begin to be magnetized. However, azimuthal velocities of ions behave differently with different degrees of magnetization, i.e., weakly magnetized ions follow rotating electrons in a right-handed direction, while fully magnetized ions revolve in left-handed direction due to electromagnetic forces. Notably, a feedback effect on total magnetic field due to plasma motion identified in other studies is not found to be present in the working conditions of the AF-MPDT examined here.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

The magnetic furnace: intense core dynamos in B stars

The dynamo action achieved in the convective cores of main-sequence massive stars is explored here through three-dimensional (3D) global simulations of convective core dynamos operating within a young 10 M{sub ⊙} B-type star, using the anelastic spherical harmonic code. These simulations capture the inner 65% of this star by radius, encompassing the convective nuclear-burning core (about 23% by radius) and a portion of the overlying radiative envelope. Eight rotation rates are considered, ranging from 0.05% to 16% of the surface breakup velocity, thereby capturing both convection that barely senses the effects of rotation and other situations in which the Coriolis forces are prominent. The vigorous dynamo action realized within all of these turbulent convective cores builds magnetic fields with peak strengths exceeding a megagauss, with the overall magnetic energy (ME) in the faster rotators reaching super-equipartition levels compared to the convective kinetic energy (KE). The core convection typically involves turbulent columnar velocity structures roughly aligned with the rotation axis, with magnetic fields threading through these rolls and possessing complex linkages throughout the core. The very strong fields are able to coexist with the flows without quenching them through Lorentz forces. The velocity and magnetic fields achieve such a state by being nearly co-aligned, and with peak magnetic islands being somewhat displaced from the fastest flows as the intricate evolution proceeds. As the rotation rate is increased, the primary force balance shifts from nonlinear advection balancing Lorentz forces to a magnetostrophic balance between Coriolis and Lorentz forces.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

RECONSTRUCTION OF INDIVIDUAL DOSES DUE TO MEDICAL EXPOSURES FOR MEMBERS OF THE TECHA RIVER COHORT

Purpose: To describe a methodology for reconstruction of doses due to medical exposures for members of the Techa River Cohort (TRC) who received diagnostic radiation at the clinic of the Urals Research Center for Radiation Medicine (URCRM) in 1952–2005. To calculate doses of medical exposure for the TRC members and compare with the doses that resulted from radioactive contamination of the Techa River. Material and Methods: Reconstruction of individual medical doses is based on data on x-ray diagnostic procedures available for each person examined at the URCRM clinics and values of absorbed dose in 12 organs per typical x-ray procedure calculated with the use of a mathematical phantom. Personal data on x-ray diagnostic examinations have been complied in the computerized “Registry of x-ray diagnostic procedures.” Sources of information are archival registry books from the URCRM x-ray room (available since 1956) and records on x-ray diagnostic procedures in patient-case histories (since 1952). The absorbed doses for 12 organs of interest have been evaluated per unit typical x-ray procedure with account taken of the x-ray examination parameters characteristic for the diagnostic machines used at the URCRM clinics. These parameters have been evaluated from published data on technical characteristics of the x-ray diagnostic machines used at the URCRM clinics in 1952–1988 and taken from the x-ray room for machines used at the URCRM in 1989–2005. Absorbed doses in the 12 organs per unit typical x-ray procedure have been calculated with use of a special computer code, EDEREX, developed at the Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev. Individual accumulated doses of medical exposure have been calculated with a computer code, MEDS (Medical Exposure Dosimetry System), specifically developed at the URCRM. Results: At present, the “Registry of x-ray diagnostic procedures” contains information on individual x-ray examinations for over 9,500 persons including 6,415 TRC members. Statistical analysis of the Registry data showed that the more frequent types of examinations were fluoroscopy and radiography of the chest and fluoroscopy of the stomach and the esophagus. Average absorbed doses accumulated by year 2005 calculated for the 12 organs varied from 4 mGy for testes to 40 mGy for bone surfaces. Maximum individual medical doses could reach 500–650 mGy and in some cases exceeded doses from exposure at the Techa River. Conclusions: For the first time the doses of medical exposure were calculated and analyzed for members of the Techa River Cohort who received diagnostic radiation at the URCRM clinics. These results are being used in radiation-risk analysis to adjust for this source of confounding exposure in the TRC.

dose reconstruction↗
DOE OSTI2013

LOW MACH NUMBER MODELING OF CORE CONVECTION IN MASSIVE STARS

This work presents three-dimensional simulations of core convection in a 15 M{sub Sun} star halfway through its main sequence lifetime. To perform the necessary long-time calculations, we use the low Mach number code MAESTRO, with initial conditions taken from a one-dimensional stellar model. We first identify several key factors that the one-dimensional initial model must satisfy to ensure efficient simulation of the convection process. We then use the three-dimensional simulations to examine the effects of two common modeling choices on the resulting convective flow: using a fixed composition approximation and using a reduced domain size. We find that using a fixed composition model actually increases the computational cost relative to using the full multi-species model because the fixed composition system takes longer to reach convection that is in a quasi-static state. Using a reduced (octant rather than full sphere) simulation domain yields flow with statistical properties that are within a factor of two of the full sphere simulation values. Both the octant and full sphere simulations show similar mixing across the convection zone boundary that is consistent with the turbulent entrainment model. However, the global character of the flow is distinctly different in the octant simulation, showing more rapid changes in the large-scale structure of the flow and thus a more isotropic flow on average.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

The Dark Energy Survey Data Processing and Calibration System

The Dark Energy Survey (DES) is a 5000 deg2 grizY survey reaching characteristic photometric depths of 24th magnitude (10 sigma) and enabling accurate photometry and morphology of objects ten times fainter than in SDSS. Preparations for DES have included building a dedicated 3 deg2 CCD camera (DECam), upgrading the existing CTIO Blanco 4m telescope and developing a new high performance computing (HPC) enabled data management system (DESDM). The DESDM system will be used for processing, calibrating and serving the DES data. The total data volumes are high (~2PB), and so considerable effort has gone into designing an automated processing and quality control system. Special purpose image detrending and photometric calibration codes have been developed to meet the data quality requirements, while survey astrometric calibration, coaddition and cataloging rely on new extensions of the AstrOmatic codes which now include tools for PSF modeling, PSF homogenization, PSF corrected model fitting cataloging and joint model fitting across multiple input images. The DESDM system has been deployed on dedicated development clusters and HPC systems in the US and Germany. An extensive program of testing with small rapid turn-around and larger campaign simulated datasets has been carried out. The system has also been tested on large real datasets, including Blanco Cosmology Survey data from the Mosaic2 camera. In Fall 2012 the DESDM system will be used for DECam commissioning, and, thereafter, the system will go into full science operations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Results and Lessons Learned From the DOE Commercial Building Partnerships: Preprint

Over the course of 5 years, NREL worked with commercial building owners and their design teams in the DOE Commercial Building Partnerships (CBP) to cut energy consumption by 50% in new construction (versus code) and by 30% in existing building pilot projects (versus code or pre-retrofit operational energy use depending on the preference of the Partner) using strategies that could be replicated across their building portfolios. A number of different building types were addressed, including supermarket, retail merchandise, combination big box (general merchandise and food sales), high rise office space, and warehouse. The projects began in pre-design and included a year of measurement data to evaluate performance against design expectations. Focused attention was required throughout the entire process to achieve a design with the potential to hit the energy performance target and to operate the resulting building to reach this potential. This paper will report quantitative results and cover both the technical and the human sides of CBP, including the elements that were required to succeed and where stumbling blocks were encountered. It will also address the impact of energy performance goals and intensive energy modeling on the design process innovations and best practices.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

Clad to coolant heat transfer during RIA in PWR conditions

The power pulse during an insertion of reactivity accident (RIA) leads to a transient heating of the fuel. Heat transfer toward the coolant through the clad and associated temperature transient of the clad is of safety significance since it may largely impact the risk of clad failure. For sufficiently large enthalpy deposited within the fuel, clad temperature increases rapidly and this can lead to coolant boiling. This paper concerns the critical review of the present understanding and of the models for the clad to coolant heat transfer in RIA for PWR conditions. The results of past experiments are reviewed and the reliability of current models dedicated to these conditions is analyzed. It appears that the use of classical models for wall to fluid heat transfer does not allow predicting the clad temperature transient as measured in RIA-related experiments. The deviation is all the more large when film boiling conditions are reached. To reproduce the experimental data, some correlations of heat transfer can be fitted but the reliability of such model out of the range of conditions of the experimental data is low. It is mainly due to a rather low level of understanding of the heat transfer in very transient conditions (i.e. when the time scale of variation of the main heat transfer parameters, like a wall temperature, is less than the typical internal time scale of the heat transfer process itself). It results in a very large scattering in the numerical simulation of clad temperature when several fuel codes are considered. To improve the reliability of these calculations, it is believed that the study of transient boiling heat transfer thanks to devoted experimental facilities is required.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

HACC: extreme scaling and performance across diverse architectures, In: SC '13 Proceedings of the International Conference on High Performance Computing, Networking, Storage and Analysis

Supercomputing is evolving towards hybrid and accelerator-based architectures with millions of cores. The HACC (Hardware/Hybrid Accelerated Cosmology Code) framework exploits this diverse landscape at the largest scales of problem size, obtaining high scalability and sustained performance. Developed to satisfy the science requirements of cosmological surveys, HACC melds particle and grid methods using a novel algorithmic structure that flexibly maps across architectures, including CPU/GPU, multi/many-core, and Blue Gene systems. We demonstrate the success of HACC on two very different machines, the CPU/GPU system Titan and the BG/Q systems Sequoia and Mira, attaining unprecedented levels of scalable performance. We demonstrate strong and weak scaling on Titan, obtaining up to 99.2% parallel efficiency, evolving 1.1 trillion particles. On Sequoia, we reach 13.94 PFlops (69.2% of peak) and 90% parallel efficiency on 1,572,864 cores, with 3.6 trillion particles, the largest cosmological benchmark yet performed. HACC design concepts are applicable to several other supercomputer applications.

Computer Science↗
DOE OSTI2026

Augmenting Molecular Graphs with Geometries via Machine Learning Interatomic Potentials

Accurate molecular property predictions require 3D geometries, which are typically obtained using expensive methods such as density functional theory (DFT). Here, we attempt to obtain molecular geometries by relying solely on machine learning interatomic potential (MLIP) models. To this end, we first curate a large-scale molecular relaxation dataset comprising 3.5 million molecules and 300 million snapshots. Then MLIP pre-trained models are trained with supervised learning to predict energy and forces given 3D molecular structures. Once trained, we show that the pre-trained models can be used in different ways to obtain geometries either explicitly or implicitly. First, it can be used to obtain approximate low-energy 3D geometries via geometry optimization. While these geometries do not consistently reach DFT-level chemical accuracy or convergence, they can still improve downstream performance compared to non-relaxed structures. To mitigate potential biases and enhance downstream predictions, we introduce geometry fine-tuning based on the relaxed 3D geometries. Second, the pre-trained models can be directly fine-tuned for property prediction when ground truth 3D geometries are available. Our results demonstrate that MLIP pre-trained models trained on relaxation data can learn transferable molecular representations to improve downstream molecular property prediction and can provide practically valuable but approximate molecular geometries that benefit property predictions. Our code is publicly available at: https://github.com/divelab/AIRS/.

Fu, Cong [Texas A & M Univ., College Station, TX (↗
DOE OSTI2018

Stop coannihilation in the CMSSM and SubGUT models

Stop coannihilation may bring the relic density of heavy supersymmetric dark matter particles into the range allowed by cosmology. The efficiency of this pro-cess is enhanced by stop-antistop annihilations into the lon-gitudinal (Goldstone) modes of the W and Z bosons, as well as by Sommerfeld enhancement of stop annihilations and the effects of bound states. Since the couplings of the stops to the Goldstone modes are proportional to the trilin-ear soft supersymmetry-breaking A -terms, these annihila-tions are enhanced when the A-terms are large. Yet, the Higgs mass may be reduced below the measured value if the A-terms are too large. Unfortunately, the interpretation of this constraint on the stop coannihilation strip is clouded by differences between the available Higgs mass calculators. For our study, we use as our default calcula-tor FeynHiggs 2.13.0, the most recent publicly avail-able version of this code. Exploring the CMSSM parameter space, we find that along the stop coannihilation strip the masses of the stops are severely split by the large A-terms. This suppresses the Higgs mass drastically for μ and A 0 > 0, whilst the extent of the stop coannihilation strip is limited for A 0 < 0 and either sign of μ. However, in sub-GUT models, reduced renormalization-group running mitigates the effect of the large A-terms, allowing larger LSP masses to be consistent with the Higgs mass calculation. We give examples where the dark matter particle mass may reach ≳ 8 TeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Kinetic simulation of the O-X conversion process in dense magnetized plasmas

One scheme for heating a dense magnetized plasma core, such as in a tokamak, involves launching an ordinary (O) electromagnetic wave at the low density edge. It is converted to a reflected extraordinary (X) electromagnetic wave under certain conditions, and then transformed into an electron Bernstein wave able to reach high density regions inaccessible to most other waves. The O-X mode conversion is important in heating and diagnostic processes in different devices such as tokamaks, stellarators, and some types of pinches. The goal of this study has been to demonstrate that the kinetic particle-in-cell (PIC) scheme is suitable for modeling the O-X conversion process as the first step toward a more complete simulation of O-X-B heating. The O-X process is considered and simulated with a kinetic particle model for parameters of the TJ-II stellarator using the PIC code, XOOPIC. This code is able to model the non-monotonic density and the magnetic profile of the TJ-II stellarator. It can also statistically represent the self-consistent distribution function of the plasma, which has not been possible in previous fluid models. By considering the electric and magnetic components of launched and reflected waves, the O-mode and X-mode waves can be detected, and the O-X conversion can be demonstrated. In this work, the optimum angle for conversion efficiency, as predicted by the previous theory and experimentally confirmed, is used. Via considering the power of the launched O-mode wave and the converted X-mode wave, the efficiency of 63% for O-X conversion for the optimum theoretical launch angle of 47{sup ∘} is obtained, which is in good agreement with efficiencies computed via full-wave simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

EXTENDED Ly{alpha} EMISSION FROM INTERACTING GALAXIES AT HIGH REDSHIFTS

Recent observations have discovered a population of extended Ly{alpha} sources, dubbed Ly{alpha} blobs (LABs), at high redshift z {approx} 2-6.6. These LABs typically have a luminosity of L {approx} 10{sup 42}-10{sup 44} erg s{sup -1}, and a size of tens of kiloparsecs, with some giant ones reaching up to D {approx} 100 kpc. However, the origin of these LABs is not well understood. In this paper, we investigate a merger model for the formation of LABs by studying Ly{alpha} emission from interacting galaxies at high redshifts by means of a combination of hydrodynamics simulations with three-dimensional radiative transfer calculations. Our galaxy simulations focus on a set of binary major mergers of galaxies with a mass range of 3-7 Multiplication-Sign 10{sup 12} M{sub Sun} in the redshift range z {approx} 3-7, and we use the newly improved ART{sup 2} code to perform the radiative transfer calculations, which couple multi-wavelength continuum, ionization of hydrogen, and Ly{alpha} line emission. We find that intense star formation and enhanced cooling induced by gravitational interaction produce strong Ly{alpha} emission from these merging galaxies. The Ly{alpha} emission appears to be extended due to the extended distribution of sources and gas. During the close encounter of galaxy progenitors when the star formation rate peaks at {approx}10{sup 3} M{sub Sun} yr{sup -1}, our model produces LABs with luminosity of L {approx} 10{sup 42}-10{sup 44} erg s{sup -1}, and size of D {approx} 10-20 kpc at z > 6 and D {approx} 20-50 kpc at z {approx} 3, in broad agreement with observations in the same redshift range. Our results suggest that merging galaxies may produce some typical LABs as observed, but the giant ones may be produced by mergers more massive than those in our model, or a combination of mergers and cold accretion from filaments on a large scale.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

24.77 Pflops on a Gravitational Tree-Code to Simulate the Milky Way Galaxy with 18600 GPUs, In: SC '14: Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis

We have simulated, for the first time, the long term evolution of the Milky Way Galaxy using 51 billion particles on the Swiss Piz Daint supercomputer with our N-body gravitational tree-code Bonsai. Herein, we describe the scientific motivation and numerical algorithms. The Milky Way model was simulated for 6 billion years, during which the bar structure and spiral arms were fully formed. This improves upon previous simulations by using 1000 times more particles, and provides a wealth of new data that can be directly compared with observations. We also report the scalability on both the Swiss Piz Daint and the US ORNL Titan. On Piz Daint the parallel efficiency of Bonsai was above 95%. The highest performance was achieved with a 242 billion particle Milky Way model using 18600 GPUs on Titan, thereby reaching a sustained GPU and application performance of 33.49 Pflops and 24.77 Pflops respectively.

Computer Science↗
DOE OSTI2019

Simulations of high-velocity impacts on metal in preparation for the Psyche mission

In 2026, the NASA Discovery mission Psyche will orbit the asteroid (16) Psyche, the largest known metal-rich asteroid in the main belt. To estimate relative ages of the surface, identify re-surfacing events and better constrain Psyche's history, impact craters will be counted and characterized. No spacecraft has ever visited a metal-rich small body; therefore, laboratory-scale impact experiments and numerical simulations will play an important role in the interpretation of the mission's data. However, the planetary applications of high-velocity impacts have so far mostly been studied for silicate targets. Limited attention has been drawn to planetary objects predominantly made of metal, and more laboratory experiments and numerical calibrations are needed. As part of this effort, we present a suite of numerical simulations using an adaptative smoothed particles hydrodynamics numerical code (ASPH) reproducing a high-velocity impact experiment conducted on a steel target. This work primarily focuses on the influence of the chosen equation of state and initial distribution of flaws in the material on the estimated crater dimensions, damage and temperature. Additionally, we find that changing the EOS and initial flaw distribution affects the crater dimensions, though for a vast majority of cases the dimensions remain within 20% of the experimental values. The target is in most cases only locally weakened but not fully damaged, independently from the EOS chosen. Finally, temperatures at the impact point and around the forming crater can reach values above the melting point of iron at <100 GPa, which is in agreement with experimental observations. These results allow us to speculate on the differences expected between the surfaces of visited silicate-rich asteroids and that of the metal-rich target of the Psyche mission.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Fast ion transport by sawtooth instability in the presence of ICRF-NBI synergy in JET plasmas

JET experiments have shown that the three-ion scenarios using waves in the ion cyclotron range of frequencies (ICRF) is an efficient way to build fast ion population through beam ion acceleration by radio frequency (RF) waves. Here, such a heating scheme is applied to plasmas with at least two thermal ion species. Analysis of mixed discharges with complex heating schemes requires a workflow that allows to model thermal and fast ion transport consistently. This paper is dedicated to modelling of a mixed plasma discharge with significant fraction of fast ions and contributes to development of fast ion transport models. For interpretive analysis with the TRANSP code a JET hydrogen-deuterium (HD) plasma discharge with neutral beam injection (NBI) and ICRF heating has been chosen. The task is complicated by NBI-ICRF synergy and plasma magnetohydrodynamic activity, like sawtooth crashes. D beam ions accelerated by RF waves form a high energy tail in fast ion distribution. Significant difference between the neutron rate computed by TRANSP and measured one is observed if the same diffusivity for electrons and ions is assumed. Sensitivity studies show that uncertainties in input plasma parameters and thermal ion transport models are crucial for modelling mixed plasma discharges and increased D transport is required to reach the plasma composition consistent with diagnostic measurements at the plasma edge. Fast ion redistribution by a sawtooth instability is characterised by non-resonant transport due to reconnection of magnetic field lines and resonant transport caused by resonance interaction between the instability and fast ions. With ORBIT simulations it has been shown that resonant interaction strongly affects fast ions of high energies, like beam ions accelerated by RF waves and fusion products. For the considered case, fast ion profiles simulated by ORBIT remain peaked after the sawtooth crashes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Strategic Petroleum Reserve Cavern Leaching Monitoring CY21

Th e U.S. Strategic Petroleum Reserve (SPR) is a crude oil storage system administered by the U.S. Department of Energy. The reserve consists of 60 active storage caverns located in underground salt domes spread across four sites in Louisiana and Texas, near the Gulf of Mexico. Beginning in 2016, the SPR started executing C ongressionally mandated oil sales. The configuration of the reserve, with a total capacity of greater than 700 million barrels ( MMB ) , re quires that unsaturated water (referred to herein as ?raw? water) is injected into the storage caverns to displace oil for sales , exchanges, and drawdowns . As such, oil sales will produce cavern growth to the extent that raw water contacts the salt cavern walls and dissolves (leaches) the surrounding salt before reaching brine saturation. SPR injected a total of over 45 MMB of raw water into twenty - six caverns as part of oil sales in CY21 . Leaching effects were monitored in these caverns to understand how the sales operations may impact the long - term integrity of the caverns. While frequent sonars are the most direct means to monitor changes in cavern shape, they can be resource intensive for the number of caverns involved in sales and exchanges. An interm ediate option is to model the leaching effects and see if any concerning features develop. The leaching effects were modeled here using the Sandia Solution Mining Code , SANSMIC . The modeling results indicate that leaching - induced features do not raise co ncern for the majority of the caverns, 15 of 26. Eleven caverns, BH - 107, BH - 110, BH - 112, BH - 113, BM - 109, WH - 11, WH - 112, WH - 114, BC - 17, BC - 18, and BC - 19 have features that may grow with additional leaching and should be monitored as leaching continues in th ose caverns. Additionally, BH - 114, BM - 4, and BM - 106 were identified in previous leaching reports for recommendation of monitoring. Nine caverns had pre - and post - leach sonars that were compared with SANSMIC results. Overall, SANSMIC was able to capture the leaching well. A deviation in the SANSMIC and sonar cavern shapes was observed near the cavern floor in caverns with significant floor rise, a process not captured by SANSMIC. These results validate that SANSMIC continues to serve as a useful tool for mon itoring changes in cavern shape due to leaching effects related to sales and exchanges.

02 PETROLEUM↗