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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Platform for Automated Anomaly Detection in the Mercury Process System at the Target System in the Spallation Neutron Source

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory accelerates proton beams, which are directed toward a mercury target to generate the world’s most intense neutron beams via spallation. The target system consists of several interconnected subsystems and accounts for a major share of the facility’s overall downtime. Early detection of anomalies in the target system response can thus provide the possibility of taking corrective actions to reduce downtime. Accelerator facilities have largely focused on the beam side for data-driven fault prognostics. On the target side, SNS relies on operational shift technicians (OSTs), who respond to alarms and manually flag anomalies onto the System Tracking and Reliability (STAR) platform. This paper presents one of the first studies of using machine learning (ML) to automate anomaly detection in the target system. The study focused on the mercury process system as the first use case and employed reconstruction-based anomaly detection on minutely sampled time series signals. The pipeline was integrated into the STAR platform to autonomously rank and flag anomalies every week. The STAR platform provides a user interface for the OSTs to evaluate the flagged anomalies, thereby incorporating human feedback.

Anomaly detection↗
DOE OSTI2019

Spallation reactions induced by 4.4 GeV deuterons on lead isotopes

Independent and cumulative production cross sections for radioactive nuclear fragments from the deuteron-irradiation of isotopically enriched lead (204Pb, 206Pb, 207Pb, and 208Pb) targets were obtained for the first time. The experiment has been performed with a 4.4 GeV deuteron beam from the Nuclotron of the Laboratory of High Energy Physics (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. The production cross sections of target fragments were determined by off-line γ-ray spectroscopy. Charge dispersion and mass-yield distributions were deduced from these data. The results are discussed in terms of the relative importance of different reaction mechanisms (evaporation–spallation, fission and multifragmentation). Comparison of our results with the data from the reaction induced by protons of about the same kinetic energy per nucleon, has been performed. The coexistence of the different decay modes in the formation of the reaction residues, such as spallation, fission and multifragmentation is suggested.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2016

Preparation and testing of corrosion and spallation-resistant coatings

The goal of this project was to take a recently developed method of bonding oxide dispersion-strengthened (ODS) FeCrAl plating to nickel superalloys closer to commercial use in syngas-fired turbines. The project was designed to better understand and develop the bonding process and to determine if plating APMT®, a specific highly oxidation-resistant ODS FeCrAl alloy made by Kanthal, onto nickel-based superalloy turbine parts is a viable method for substantially improving the lifetimes and maximum use temperatures of the parts. The superalloys investigated for protection were CM247LC and Rene® 80, both alumina scale-forming alloys. The method for bonding the APMT plate to the superalloys is called evaporative metal bonding, which involves placing a thin foil of zinc between the plate and the superalloy, clamping them together, and heating in an atmosphere-controlled furnace. Upon heating, the zinc melts and dissolves the oxide skins of the alloys at the bond line, allowing the two alloys to diffuse into each other. The zinc then diffuses through the alloys and evaporates from their surfaces, creating a bond between the APMT and the superalloy that is stronger than the APMT itself. Testing showed that the diffusivity of zinc in both APMT and CM247LC is quite similar at 700°C but 15 times higher in the APMT at 1214°C. Coefficients of thermal expansion were determined for each of the alloys as a function of temperature. This information was entered into a finite-element model using ANSYS, which was used to design a clamping jig for pressing the APMT to the superalloys at the bonding temperature. Scanning electron microscopy analyses of representative joints showed that no zinc remained in the alloys after bonding Unfortunately, the analyses also showed some small pieces of broken aluminum oxide scale near the bond lines, indicating that its scale was not sufficiently removed during prebonding cleaning. Samples from each of the bonded blocks were sent to Siemens for its standard oxidation, spallation, and corrosion testing, which was scheduled for completion in the spring of 2016. However, because of commercial demands, the tests were not completed by the time of this report except some initial spallation tests at 1150°C. In those tests, several of the APMT plates separated from the CM247LC, likely because of the remaining aluminum oxide scale on the surface of the CM247LC. This implies that surface preparation may need to include machining to remove the oxide scale before bonding rather than just sandblasting. In previous tensile testing at 950°C, the breaks in the tensile samples always occurred in the APMT and not at the joints. Gasifier sampling was completed to determine what types of trace contaminants may occur in cleaned and combusted syngas and that could lead to corrosion or deposition in turbines firing coal syngas. The sampling was done from a pressurized fluidized-bed gasifier and a pressurized entrained-flow gasifier. The particles captured on a filter from syngas were typically 0.2 to 0.5 μm in diameter, whereas those captured from the combusted syngas were slightly larger and more spherical. X-ray photoelectron spectroscopy done at Oak Ridge National Laboratory showed that the particles do not contain any metals and have an atomic composition almost identical to that of the polycarbonate filter. This indicates that the particles are primarily soot-based and not formed from volatilization of metals in the gasifiers.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2026

Temperature of a tungsten spallation target

We discuss the heat load inside a neutron spallation target made of tungsten hit by an 800 MeV proton beam. This problem is important for the Neutron Target project, where a spallation target will be surrounded by an extended graphite or beryllium cube to create a neutron target. The idea of a free-neutron target enables the measurement of neutron-induced reactions in inverse kinematics. This idea is part of the LANSCE strategy to stay a worldwide leader for neutron-induced research.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1974

Titanium spallation cross sections between 30 and 584 MeV and Ar-39 activities on the moon

The production cross sections of Ar39 for Ti spallation at 45-, 319-, 433-, and 584-MeV proton energies were measured to be 0.37 + or - 0.09, 12.4 + or - 3.7, 9.1 + or - 2.7, and 17.8 + or - 6.2 mb, respectively. Normalized Ar39 production rates and activities are also derived for protons above 40 MeV and for three differential proton spectra of the type approximately E(- alpha). It is concluded that, even for samples of high-Ti content, Ti spallation by solar protons below 200-MeV energy does not contribute significantly to their Ar39 radioactivity.

Steinburnn, F.↗
NASA NTRS1974

Calculation of astrophysical spallation reactions using the RENO model

The RENO model for the Monte-Carlo treatment of astrophysical spallation reactions has been used to generate preliminary cross-sections for the purpose of illustrating the discrete-nucleon approach to spallation modeling and to exhibit differences between two versions of RENO. Comparisons with experimental, theoretical, and semiempirical data demonstrate the practicability of the discrete-nucleon approach.-

Ayres, C. L.↗
NASA NTRS1974

Titanium spallation cross sections between 30 and 584 MeV and Ar-39 activities on the moon

The production cross sections of Ar-39 for Ti spallation at 45-, 319-, 433-, and 584-MeV proton energies were measured to be 0.37 + or - 09, 12.4 + or - 3.7, 9.1 + or - 2.7, and 17.8 + or - 6.2 mb, respectively. Normalized Ar-39 production rates and activities are also derived for protons above 40 Mev and for three differential proton spectra. It is concluded that even for samples of high-Ti content, Ti spallation by solar protons below 200-MeV energy does not contribute significantly to their Ar-39 radioactivity.

Steinbrunn, F.↗
NASA NTRS1985

Calculation of improved spallation cross sections

Several research groups have recently carried out highly precise measurements (to about 10 percent) of high-energy nuclear spallation cross sections. These measurements, above 5 GeV, cover a broad range of elements: V, Fe, Cu, Ag, Ta and Au. Even the small cross sections far off the peak of the isotopic distribution curves have been measured. The semiempirical calculations are compared with the measured values. Preliminary comparisons indicate that the parameters of our spallation relations (Silberberg and Tsao, 1973) for atomic numbers 20 to 83 need modifications, e.g. a reduced slope of the mass yield distribution, broader isotopic distributions, and a shift of the isotopic distribution toward the neutron-deficient side. The required modifications are negligible near Fe and Cu, but increase with increasing target mass.

Tsao, C. H.↗
NASA NTRS1992

CNO destruction by spallation and type I X-ray bursts

Recent work on the surface boundary conditions of accreting neutron stars indicates that appreciable amounts of CNO elements can be destroyed by spallation. Previous authors assume an accretion of near-solar-abundance material which is not altered by boundary effects. Steady state models of accreting neutron stars are constructed assuming all but traces of metals are destroyed due to spallation in the surface layers. Models with solar accretion for comparison are also constructed. The models are compared with Exosat observations of 4U/MXB 1636 - 53. It is found that the simplifications introduced by assuming CNO destruction does not bring theory closer to describing what is observed.

Tillett, Jason C.↗
NASA NTRS1993

Separation of spallation and terrestrial C-14 in chondrites

Weathering products and contamination severely hamper our ability to accurately measure the C-14 spallation component in meteorites, but can give insights into a sample's terrestrial history. A procedure was developed to measure the C-14 in these components using CO and CO2 separations from temperature extractions from 200-500 mg of material. The Bruderheim (L6) chondrite was chosen as a standard following the practice of previous researchers, crosschecked against Peace River (L6), Abee (EH4), and Juvinas (EUC). Low temperature fractions (less than 900 C) give C-14 signatures consistent with a modern terrestrial C-14 source; melt fractions show elevated levels attesting to a spallogenic origin. Higher yields of CO in the melt fraction are less affected by the low levels of experimental contamination than the CO2. This fraction gave a mean CO:CO2 ratio in Bruderheim of 81.6 +/- 7.7; the ratio of the spallation component is 79.8 +/- 8.1. These values suggest equilibrium release of gases on the olivine-silica-pyroxene-iron buffer. This is corroborated by approximately equal release of the two components at 900 C. The chondrites gave an average saturation level of 54.3 +/- 2.9 dpm/kg; the achondrite gave 49.6 +/- 2.0 dpm/kg. No clear correlation with oxygen content is apparent, though shielding effects have yet to be evaluated. A further evaluation of this subject matter is given.

Cresswell, R. G.↗
NASA NTRS1995

Coupled Ablation, Heat Conduction, Pyrolysis, Shape Change and Spallation of the Galileo Probe

The Galileo probe enters the atmosphere of Jupiter in December 1995. This paper presents numerical methodology and detailed results of our final pre-impact calculations for the heat shield response. The calculations are performed using a highly modified version of a viscous shock layer code with massive radiation coupled with a surface thermochemical ablation and spallation model and with the transient in-depth thermal response of the charring and ablating heat shield. The flowfield is quasi-steady along the trajectory, but the heat shield thermal response is dynamic. Each surface node of the VSL grid is coupled with a one-dimensional thermal response calculation. The thermal solver includes heat conduction, pyrolysis, and grid movement owing to surface recession. Initial conditions for the heat shield temperature and density were obtained from the high altitude rarefied-flow calculations of Haas and Milos. Galileo probe surface temperature, shape, mass flux, and element flux are all determined as functions of time along the trajectory with spallation varied parametrically. The calculations also estimate the in-depth density and temperature profiles for the heat shield. All this information is required to determine the time-dependent vehicle mass and drag coefficient which are necessary inputs for the atmospheric reconstruction experiment on board the probe.

Milos, Frank S.↗
NASA NTRS1990

Spallation processes and nuclear interaction products of cosmic rays

Most cosmic-ray nuclei heavier than helium have suffered nuclear collisions in the interstellar gas, with transformation of nuclear composition. The isotopic and elemental composition at the sources has to be inferred from the observed composition near the Earth. The source composition permits tests of current ideas on sites of origin, nucleosynthesis in stars, evolution of stars, the mixing and composition of the interstellar medium and injection processes prior to acceleration. The effects of nuclear spallation, production of radioactive nuclides and the time dependence of their decay provide valuable information on the acceleration and propagation of cosmic rays, their nuclear transformations, and their confinement time in the Galaxy. The formation of spallation products that only decay by electron capture and are relatively long-lived permits an investigation of the nature and density fluctuations (like clouds) of the interstellar medium. Since nuclear collisions yield positrons, antiprotons, gamma rays and neutrinos, we shall discuss these topics briefly.

Non-NASA Center↗
DOE OSTI2017

A Simplified Quantitative Model for Fissile Material Production from Fast Spallation Neutrons

The Accelerator Driven System (ADS) as a reactor to produce fissile material, or for partitioning & transmutation purposes, has potential as an inherently safe reactor since it can be shut down by simply turning off the accelerator. Multiple studies have focused on the intranuclear and internuclear physics involved in the spallation process for high-energy projectiles impacting high-Z targets relevant to ADS applications. To quantify spallation neutronics, and thereby fissile material production, generally requires numerical methods such as MCNP, and such calculations are specific to the geometry under consideration. This study uses published cross sections from the ENDF database and an assumed generic cylindrical geometry for the ADS target and fertile blanket to derive analytic expressions for the production of Pu-239 and U-233, without needing to run MCNP codes, yet matching published data.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Automating Anomaly Detection for Target systems at Spallation Neutron Source

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory, produces the world’s most intense pulse neutrons beams. An accelerated proton beam is directed into a mercury target to generate neutrons via spallation. The target system accounted for over 40% of the overall downtime of the facility in 2022. Thus, early detection in anomalies in the target systems can enable taking corrective actions to avoid failures and reduce downtime. Fault prognostics and anomaly detection in accelerators, both at SNS and outside, has largely focused on the beam side. This paper presents one the first studies exploring leveraging machine learning to automate the detection of anomalies in the target system. The target system consists of over 30 different interconnected subsystems, and the present work focuses on the mercury process system as a use case. Analyzing data from 28 process variables from 2022 and 2023, tree-based and reconstruction-based algorithms are employed to detect anomalies in archived data. The algorithms detected previously unreported anomalies, several of which were deemed alert worthy by human experts, particularly those found by reconstruction-based algorithms. Using data from each production run in the accelerator increased the generalizability of the models in time. Efforts are now underway to implement a workflow for incorporating human feedback to update the models and evaluating performance on unseen data. The models will eventually be integrated into the existing System Tracking and Reliability system with a web interface for automated anomaly detection and reporting along with a pathway for incorporating human feedback for model updates.

Raj, Anant [ORNL] (ORCID:0000000306711244)↗
DOE OSTI2015

Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values. Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associated with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscattering analysis (EBSD). It was also shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by necklaces of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. Moreover, the propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the larger than expected data scatter.

316L↗
DOE OSTI2025

Simulation and measurement of the dynamic strain response in a prototypical spallation target

The Second Target Station (STS) at the Spallation Neutron Source (SNS) will address emerging scientific challenges by providing a source of intense cold neutrons to instruments optimized for this source. The STS target will use rotating tungsten blocks and will receive 1.3 GeV proton beam pulses from the SNS accelerator at a repetition rate of 15 Hz. The facility life is planned for 40 years, and each target assembly life is expected to be approximately 10 years. An accurate strain prediction is then critical for fatigue life assessment of STS target blocks because they will be subject to approximately 10 8 beam pulses per lifetime. As an R&D activity, the Los Alamos Neutron Science Center (LANSCE) Weapons Neutron Research (WNR) Target 2 (Blue Room) facility was used to test the strain response of prototypical target blocks to the thermal shock of a proton pulse. The blue room was well suited for a pulsed proton beam impact test of subscale STS target blocks; the 800 MeV proton energy is approximately 60 % of the 1.3 GeV proton energy expected from the SNS accelerator to the STS. The LANSCE Proton Storage Ring (PSR) and SNS are both short-pulse proton beam sources with nominal pulse widths of 250 ns and 661 ns, respectively, so the energy deposition in the target occurs in <1 μs pulse duration. Strain measurements on the outer surface of three target blocks (bare tungsten, tantalum-clad tungsten, niobium-clad tungsten) were recorded for comparison against neutronics and structural simulations. In conclusion, this experiment and the supporting simulations satisfied the following primary research goals for the STS target.

Dynamic strain response↗
DOE OSTI2016

VESPA: The vibrational spectrometer for the European Spallation Source

VESPA, Vibrational Excitation Spectrometer with Pyrolytic-graphite Analysers, aims to probe molecular excitations via inelastic neutron scattering. It is a thermal high resolution inverted geometry time-of-flight instrument designed to maximise the use of the long pulse of the European Spallation Source. The wavelength frame multiplication technique was applied to provide simultaneously a broad dynamic range (about 0-500 meV) while a system of optical blind choppers allows to trade flux for energy resolution. Thanks to its high flux, VESPA will allow the investigation of dynamical and in situ experiments in physical chemistry. Here we describe the design parameters and the corresponding McStas simulations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Conceptual design of the time-of-flight backscattering spectrometer, MIRACLES, at the European Spallation Source

In this work, we present the conceptual design of the backscattering time-of-flight spectrometer MIRACLES approved for construction at the long-pulse European Spallation Source (ESS). MIRACLES’s unparalleled combination of variable resolution, high flux, extended energy, and momentum transfer (0.2–6 Å{sup −1}) ranges will open new avenues for neutron backscattering spectroscopy. Its remarkable flexibility can be attributed to 3 key elements: the long-pulse time structure and low repetition rate of the ESS neutron source, the chopper cascade that tailors the moderator pulse in the primary part of the spectrometer, and the bent Si(111) analyzer crystals arranged in a near-backscattering geometry in the secondary part of the spectrometer. Analytical calculations combined with instrument Monte-Carlo simulations show that the instrument will provide a variable elastic energy resolution, δ(ħ ω), between 2 and 32 μeV, when using a wavelength of λ ≈ 6.267 Å (Si(111)-reflection), with an energy transfer range, ħ ω, centered at the elastic line from −600 to +600 μeV. In addition, when selecting λ ≈ 2.08 Å (i.e., the Si(333)-reflection), δ(ħ ω) can be relaxed to 300 μeV and ħ ω from about 10 meV in energy gain to ca −40 meV in energy loss. Finally, the dynamic wavelength range of MIRACLES, approximately 1.8 Å, can be shifted within the interval of 2–20 Å to allow the measurement of low-energy inelastic excitations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗