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DOE OSTI2017

Microstructure of In-Core Molten Salt Corrosion Hastelloy N{sup R} and 316 Stainless Steel

Since 2011, many materials have been discussed for potential application in Fluoride salt-cooled High-temperature nuclear Reactors (FHRs), which are emerging as leading reactor concept for the next generation of nuclear reactors thanks to the benefits of a high degree of passive safety, high thermal efficiency, and low spent fuel volume. Among these discussed materials, Hastelloy N{sup R} and 316L stainless steel have been selected as the most likely candidate alloys for FHRs. To provide direct experience in integrating a real system using molten FLiBe salt for reactor operation, these two candidate alloys were experimentally tested in Li-7 enriched Li{sub 2}BeF{sub 4} (FLiBe) molten salt in the core of MIT Research Reactor (MITR) at 700 deg. C for 1000 hours. After in-core corrosion testing, some basic post-irradiation examinations (PIE) including weight change per unit area and surface profile as well as surface morphology were conducted in the MIT Nuclear Reactor Laboratory (NRL) and compared with out-of-reactor corrosion samples. The deep understanding of these alloys in high-temperature molten salt with strong neutron irradiation requires further microstructural analysis such as electron microscopy and energy dispersive spectroscopy on the surface and cross-section of the in-core corrosion tested samples. The challenge in the microstructural analysis is due to the high radioactivity from the gamma emitting isotopes formed in alloys during neutron irradiation. Additionally, the facilities that are authorized for radioactive materials are very limited on campus. In this study, the microstructure of the in-core corrosion tested Hastelloy N{sup R} and 316L stainless steel specimen was analyzed by using the facilities at the Center for Advanced Energy Studies (CAES) at Idaho National Laboratory (INL) through the Nuclear Science User Facilities (NSUF) Rapid Turnaround Experiment (RTE) program.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS2010

Petrology of the Crystalline Rocks Hosting the Santa Fe Impact Structure

We collected samples from within the area of shatter cone occurrence and for approximately 8 kilometers (map distance) along the roadway. Our primary goal is to date the impact. Our secondary goal is to use the petrology and Ar systematics to provide further insight into size and scale of the impact. Our approach is to: Conduct a detailed petrology study to identify lithologies that share petrologic characteristics and tectonic histories but with differing degrees of shock. Obtain micro-cores of K-bearing minerals from multiple samples for Ar-40/Ar-39 analysis. Examine the Ar diffusion patterns for multiple minerals in multiple shocked and control samples. This will help us to better understand outcrop and regional scale relationships among rocks and their responses to the impact event.

Schrader, C. M.↗

NASA NTRS1995

Planetary and Primitive Object Strength Measurement and Sampling Apparatus

Support is requested for continuation of a program of dynamic impact (harpoon) coring of planetary, comet, or asteroid surface materials. We have previously demonstrated that good quality cores are obtainable for planetary materials with compressive strengths less than 200 MPa. Since the dynamics of penetration are observable on a Discovery class spacecraft, which images the sampling operation, these data can be used with a model developed under this project, to measure in-situ strength and frictional strength of the crust of the object. During the last year we have developed a detailed analytic model of penetrator mechanics. Progress is reported for the solid penetrators experiments, the CIT penetrator model, and the impact spall sampling apparatus.

Ahrens, Thomas J.↗

NASA NTRS2011

Compression Behavior of Fluted-Core Composite Panels

In recent years, fiber-reinforced composites have become more accepted for aerospace applications. Specifically, during NASA s recent efforts to develop new launch vehicles, composite materials were considered and baselined for a number of structures. Because of mass and stiffness requirements, sandwich composites are often selected for many applications. However, there are a number of manufacturing and in-service concerns associated with traditional honeycomb-core sandwich composites that in certain instances may be alleviated through the use of other core materials or construction methods. Fluted-core, which consists of integral angled web members with structural radius fillers spaced between laminate face sheets, is one such construction alternative and is considered herein. Two different fluted-core designs were considered: a subscale design and a full-scale design sized for a heavy-lift-launch-vehicle interstage. In particular, axial compression of fluted-core composites was evaluated with experiments and finite-element analyses (FEA); axial compression is the primary loading condition in dry launch-vehicle barrel sections. Detailed finite-element models were developed to represent all components of the fluted-core construction, and geometrically nonlinear analyses were conducted to predict both buckling and material failures. Good agreement was obtained between test data and analyses, for both local buckling and ultimate material failure. Though the local buckling events are not catastrophic, the resulting deformations contribute to material failures. Consequently, an important observation is that the material failure loads and modes would not be captured by either linear analyses or nonlinear smeared-shell analyses. Compression-after-impact (CAI) performance of fluted core composites was also investigated by experimentally testing samples impacted with 6 ft.-lb. impact energies. It was found that such impacts reduced the ultimate load carrying capability by approximately 40% on the subscale test articles and by less than 20% on the full-scale test articles. Nondestructive inspection of the damage zones indicated that the detectable damage was limited to no more than one flute on either side of any given impact. More study is needed, but this may indicate that an inherent damage-arrest capability of fluted core could provide benefits over traditional sandwich designs in certain weight-critical applications.

Schultz, Marc R.↗

NASA NTRSDate not supplied

Emulation of Core Flight System Applications for Flight Software Development and Validation

The Mars Sample Return (MSR) campaign is an unprecedented attempt in the return of Martian samples back to Earth. The ascent from the surface will be performed by the Mars Ascent Vehicle (MAV), a critical element in the mission that National Aeronautics and Space Administration (NASA) Marshall Space Flight Center (MSFC) is developing. To this end, innovations in flight software development, verification, and validation are occurring. The MAV flight computer will run Core Flight System (cFS), an open-source software environment developed by NASA Goddard Space Flight Center (GSFC). NASA Marshall’s MAV Mission and Fault Management (M&FM) Team has implemented an emulation of two applications of this architecture: Limit Checker and Stored Command. Using an emulation of the functionalities of these applications allows for rapid prototyping of table-based algorithms. Further, M&FM is leveraging an in-house, low-fidelity but high-throughput State Analysis Model (SAM), an integrated MATLAB Stateflow Plant and Software model. This model is run in parallel with the cFS emulation for full flyout testing of the M&FM algorithms, verification of intent of these algorithms, and for future auto-generation of application-ingestible M&FM tables. The tables can then be delivered to the MAV Flight Software (FSW) team in a seamless process, reducing the cost of traditional FSW development and the risk of starting M&FM FSW development at later points in the NASA program life cycle.

Cody Wheeler↗

NASA NTRSDate not supplied

Emulation of Core Flight System Applications for Flight Software Development and Validation

Cody Wheeler↗

NASA NTRS1988

Primary sedimentary structures and the internal architecture of a Martian sand body in search of evidence for sand transport and deposition

Lunar experiences show that unmanned sample return missions, despite limitations on sample size, can produce invaluable data to infer crustal processes, regolith processes, regolith-atmosphere/ionosphere interaction processes, etc. Drill cores provide a record of regolith evolution as well as a more complete sample of the regolith than small scoops and/or rakes. It is proposed that: (1) a hole be drilled in a sand body to obtain continuous oriented cores; a depth of about 10 m would be compatible with what we know of bed form hierarchy of terrestrial stream deposits; (2) two trenches, at right angles to each other and close to the drill-hole, be dug and the walls scraped lightly such that primary/internal sedimentary structures of the sand body become visible; (3) the walls of the trenches be made gravitationally stable by impregnation techniques; (4) acetate or other peels of a strip on each wall be taken; and (5) appropriately scaled photographs of the walls be taken at different sun-angles to ensure maximum ease of interpretation of sedimentary structures; and, to correlate these structural features with those in the core at different depth levels of the core.

Basu, Abhijit↗

DOE OSTI2015

Zooming in on the progenitors of superluminous supernovae with the HST

We present Hubble Space Telescope (HST) rest-frame ultraviolet imaging of the host galaxies of 16 hydrogen-poor superluminous supernovae (SLSNe), including 11 events from the Pan-STARRS Medium Deep Survey. Taking advantage of the superb angular resolution of HST, we characterize the galaxies’ morphological properties, sizes, and star formation rate (SFR) densities. We determine the supernova (SN) locations within the host galaxies through precise astrometric matching and measure physical and host-normalized offsets as well as the SN positions within the cumulative distribution of UV light pixel brightness. We find that the host galaxies of H-poor SLSNe are irregular, compact dwarf galaxies, with a median half-light radius of just 0.9 kpc. The UV-derived SFR densities are high (〈Σ{sub SFR}〉≃0.1M{sub ⊙} yr{sup −1} kpc{sup −2}), suggesting that SLSNe form in overdense environments. Their locations trace the UV light of their host galaxies, with a distribution intermediate between that of long-duration gamma-ray bursts (LGRBs; which are strongly clustered on the brightest regions of their hosts) and a uniform distribution (characteristic of normal core-collapse SNe), though cannot be statistically distinguished from either with the current sample size. Taken together, this strengthens the picture that SLSN progenitors require different conditions than those of ordinary core-collapse SNe to form and that they explode in broadly similar galaxies as do LGRBs. If the tendency for SLSNe to be less clustered on the brightest regions than are LGRBs is confirmed by a larger sample, this would indicate a different, potentially lower-mass progenitor for SLSNe than LRGBs.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2016

Oxidation controlled phase composition of FeCo(Zr) nanoparticles in CaF{sub 2} matrix

Results of the study of oxidised (FeCoZr){sub x}(CaF{sub 2}){sub 100−x} films in a wide composition range (30 ≤ x ≤ 74 at.%) sintered at oxygen pressures P{sub O} = 4.3 and 9.8 mPa with X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), {sup 57}Fe Mössbauer spectroscopy (MS), and vibrating sample magnetometry (VSM) are reported. A “crystalline metallic core–amorphous oxide shell” structure of nanoparticles (NPs) in films oxidised at lower P{sub O} = 4.3 mPa is observed in TEM images. A combined use of XRD, MS and XAS techniques provides identification of NP phase composition evidencing α-FeCo(Zr) core of the variable content depending on x and a complex oxide shell including amorphous α-Fe{sup 3+}{sub 2}O{sub 3} together with Co{sup 2+}{sub 1−y}Fe{sup 2+}{sub y}O at low x (30–36 at.%). Full oxidation of NPs at higher P{sub O} = 9.8 mPa is indicated by TEM, XRD, MS and XAS patterns evidencing the formation of “crystalline Co{sup 2+}{sub 1−y}Fe{sup 2+}{sub y}O core–amorphous α-Fe{sup 3+}{sub 2}O{sub 3} shell” structure. Progressive oxidation of NPs with decreasing x at P{sub O} = 4.3 mPa as well as with P{sub O} increase is followed by variation of average centre shifts < δ > obtained from deconvoluted {sup 57}Fe Mössbauer spectra. Magnetometry measurements of films sintered at P{sub O} = 4.3 mPa reveal an effect of exchange bias confirming “ferromagnetic metallic core–antiferromagnetic oxide shell” structure of NPs. The results show that phase composition of oxide shells is governed both by concentration of oxygen available during synthesis and on the x. Schemes of progressive NP oxidation with identified phase composition as a function of P{sub O} and x values are proposed. - Highlights: • A selective oxidation of Fe in Fe–Co nanoparticles, NPs, is revealed. • Oxidation controlled composition of Fe–Co NPs in CaF{sub 2} matrix is determined. • “Metallic core–amorphous oxide shell”-like NPs are obtained at low oxygen pressure. • “Crystalline core–amorphous shell” oxide structures appear at high oxygen pressure. • A scheme of phase occurrence and structure of nanoparticles is proposed.

36 MATERIALS SCIENCE↗

NASA NTRS1993

Was Martian mantle wet? A possible consequence of rapid core formation

Degassing of H2O in the planetary interior possibly plays an important role in the evolution of surface environment as well as geologic activity on the terrestrial planets. Mars may be such a planet that well preserves the materials and the geologic features directly related to early evolution of H2O. H2O content in the interior of proto-Mars during accretion and also core formation were investigated. Geodetic data shows that Mars has a dense core. The existence of iron-rich core on Mars may be also supported by the depletion of siderophile elements in SNC meteorites assuming that these samples came from Mars. Isotope systematics of these meteorites indicate that the core formation occurred very early, probably concurrently with Mars formation. Considering the kinetics of metal segregation from silicate, the melting of silicate is likely to precede the core formation. Once the core formation occurs, substantial amount of gravitational energy is released and thus the planetary interior is heated. This energy may be large enough to keep the silicate material in partially molten state along with the accretional heating. Under such circumstances, the silicate melt probably migrates to the surface. Early crustal formation, therefore, is also likely to be associated with the core formation.

Kuramoto, Kiyoshi↗

DOE OSTI2016

Corium stratification test using intermediate products of degraded core materials in severe accident of BWR

Two series of corium stratification tests using samples including intermediate products (B{sub 4}C-Fe alloy, Fe-Zr alloy) in BWR severe accidents were performed to investigate the influence of initial chemical composition. Chemical features of intermediate products of degraded core materials in severe accidents are considered to change depend upon oxygen potential in the atmosphere and temperature of the products in accordance with the accident progression and the features are highly important for evaluating the relocation and stratification behavior of fuel debris, especially for boron distribution in fuel debris. The initial compositions of samples were determined based on the results of our previous control blade and channel box degradation tests. The present results indicate that the U concentration in the metallic layer largely depends on the oxygen potential in the atmosphere and the apparent red-ox reaction rate between UO{sub 2} and Zr is mitigated when the typical intermediate product B{sub 4}C-Fe alloy coexists with UO{sub 2} and Zr. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2014

Enhanced-locality fiber-optic two-photon-fluorescence live-brain interrogation

Two-photon excitation is shown to substantially enhance the locality of fiber-based optical interrogation of strongly scattering biotissues. In our experiments, a high-numerical-aperture, large-core-are fiber probe is used to deliver the 200-fs output of a 100-MHz mode-locked ytterbium fiber laser to samples of live mouse brain, induce two-photon fluorescence of nitrogen–vacancy centers in diamond markers in brain sample. Fiber probes with a high numerical aperture and a large core area are shown to enable locality enhancement in fiber-laser–fiber-probe two-photon brain excitation and interrogation without sacrificing the efficiency of fluorescence response collection.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS2000

Mars Immunoassay Life Detection Instrument (MILDI)

The direct detection of organic biomarkers for living or fossil microbes on Mars by an in situ instrument is a worthy goal for future lander missions. We have proposed an instrument based on immunological reactions to specific antibodies to cause activation of fluorescent stains. Antibodies are raised or acquired to a variety of general and specific substances that might be in Mars soil. These antibodies are then combined with various fluorescent stains and applied to small numbered spots on a small (two to three centimeters) test plate where they become firmly attached after drying. On Mars, a sample of soil from a trench or drill core is extracted with water and/or an organic solvent that is then applied to the test plate. Any substance, which has an antibody on the test plate, will react with its antibody and activate its fluorescent stain. A small ultraviolet light source will illuminate the test plate, which is observed with a small CCD camera. The numbered spots that fluoresce indicate the presence of the tested-for substance, and the intensity indicates relative amounts. The entire instrument can be quite small and light, on the order of ten cm in each dimension. A possible choice for light source may be small UV lasers at several wavelengths. Up to 1000 different sample spots can be placed on a plate 3 cm on a side, but a more practical number might be 100. Each antibody can have a redundant position for independent verification of reaction. Some of the wells or spots can contain simply standard fluorescent stains used to detect live cells, dead cells, DNA, etc. These the stains in these spots may be directly activated; no antibodies are necessary.

McKay, David↗

DOE OSTI2018

Assessing the response of methane hydrates to environmental change at the Svalbard continental margin

This project reflects the results of cooperative research efforts between the US Department of Energy and scientists from Norway and Germany, who collaboratively designed the study, collected and analyzed samples from the water column and sediment and arrive at conclusions presented in joint publications. The main goal of the project was to assess the role of gas hydrate deposits in modulating methane discharge revealed through water column data, and assess the changes in environmental parameters, geochemical and microbiological conditions that drive the methane release in this high latitude region. Samples and data were collected from seven expeditions that encompassed extensive water column surveys, gravity coring, remotely-operated towed instrumentation and seafloor drilling campaigns. Geochemical and microbiological results were interpreted in the context of correlative geophysical data and numerical models, to generate a comprehensive and interdisciplinary view of the processes operating along the Svalbard margin. Incubation experiments complement the filed observations and provide additional data on the microbiological response to methane change. Collectively our results show that methane seepage in this margin is a component of a large methane plume, the Svalbard plume, which is not associated with gas hydrate processes. Consistently, numerical models of data from shallow (gravity cores offshore Storfjordrenna, bearing gas hydrate) and deep (MeBo drilling offshore Prins Karls Foreland) sediment samples show that methane and gas hydrate dynamics at sites that lie within the upper edge of gas hydrate stability are not responding to modern changes in bottom water temperature. Rather the data point to a long history of methane release, dominantly controlled by large scale Earth system changes (e.g., geology, oceanography, and glaciology) with gas hydrate as a temporary methane reservoir. Further results document the episodicity of the methane release, the role of microbes in sequestering methane carbon into authigenic carbonate, reaction networks involved in carbon recycling pathways at the sulfate-methane transition, and response of microbial communities to changes in methane flux allowing for a richer understanding of microbial ecology in response to change at methane seep sites.

58 GEOSCIENCES↗

NASA NTRS1983

An upper bound on the radius of a highly electrically conducting lunar core

Parker's (1980) nonlinear inverse theory for the electromagnetic sounding problem is converted to a form suitable for analysis of lunar day-side transfer function data by: (1) transforming the solution in plane geometry to that in spherical geometry; and (2) transforming the theoretical lunar transfer function in the dipole limit to an apparent resistivity function. The theory is applied to the revised lunar transfer function data set of Hood et al. (1982), which extends in frequency from 10 to the -5th to 10 to the -3rd Hz. On the assumption that an iron-rich lunar core, whether molten or solid, can be represented by a perfect conductor at the minimum sampled frequency, an upper bound of 435 km on the maximum radius of such a core is calculated. This bound is somewhat larger than values of 360-375 km previously estimated from the same data set via forward model calculations because the prior work did not consider all possible mantle conductivity functions.

Hobbs, B. A.↗

DOE OSTI2016

Fukushima Daiichi reactor source term attribution using cesium isotope ratios from contaminated environmental samples

Source term attribution of environmental contamination following the Fukushima Daiichi Nuclear Power Plant (FDNPP) disaster is complicated by a large number of possible similar emission source terms (e.g. FDNPP reactor cores 1–3 and spent fuel ponds 1–4). Cesium isotopic analyses can be utilized to discriminate between environmental contamination from different FDNPP source terms and, if samples are sufficiently temporally resolved, potentially provide insights into the extent of reactor core damage at a given time. In this work, rice, soil, mushroom, and soybean samples taken 100–250 km from the FDNPP site were dissolved using microwave digestion. Radiocesium was extracted and purified using two sequential ammonium molybdophosphate-polyacrylonitrile columns, following which 135 Cs/ 137 Cs isotope ratios were measured using thermal ionization mass spectrometry (TIMS). Results were compared with data reported previously from locations to the northwest of FDNPP and 30 km to the south of FDNPP. 135 Cs/ 137 Cs isotope ratios from samples 100–250 km to the southwest of the FDNPP site show a consistent value of 0.376 ± 0.008. 135 Cs/ 137 Cs versus 134 Cs/ 137 Cs correlation plots suggest that radiocesium to the southwest is derived from a mixture of FDNPP reactor cores 1, 2, and 3. Conclusions from the cesium isotopic data are in agreement with those derived independently based upon the event chronology combined with meteorological conditions at the time of the disaster. In conclusion, cesium isotopic analyses provide a powerful tool for source term discrimination of environmental radiocesium contamination at the FDNPP site. For higher precision source term attribution and forensic determination of the FDNPP core conditions based upon cesium, analyses of a larger number of samples from locations to the north and south of the FDNPP site (particularly time-resolved air filter samples) are needed. Published in 2016. This article is a U.S. Government work and is in the public domain in the USA.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2013

THE DENSITY PROFILES OF MASSIVE, RELAXED GALAXY CLUSTERS. II. SEPARATING LUMINOUS AND DARK MATTER IN CLUSTER CORES

We present stellar and dark matter (DM) density profiles for a sample of seven massive, relaxed galaxy clusters derived from strong and weak gravitational lensing and resolved stellar kinematic observations within the centrally located brightest cluster galaxies (BCGs). In Paper I of the series, we demonstrated that the total density profile derived from these data, which span three decades in radius, is consistent with numerical DM-only simulations at radii {approx}> 5-10 kpc, despite the significant contribution of stellar material in the core. Here, we decompose the inner mass profiles of these clusters into stellar and dark components. Parameterizing the DM density profile as a power law {rho}{sub DM}{proportional_to}r {sup -{beta}} on small scales, we find a mean slope ({beta}) = 0.50 {+-} 0.10(random){sup +0.14} {sub -0.13}(systematic). Alternatively, cored Navarro-Frenk-White (NFW) profiles with (log r {sub core}/kpc) = 1.14 {+-} 0.13{sup +0.14} {sub -0.22} provide an equally good description. These density profiles are significantly shallower than canonical NFW models at radii {approx}< 30 kpc, comparable to the effective radii of the BCGs. The inner DM profile is correlated with the distribution of stars in the BCG, suggesting a connection between the inner halo and the assembly of stars in the central galaxy. The stellar mass-to-light ratio inferred from lensing and stellar dynamics is consistent with that inferred using stellar population synthesis models if a Salpeter initial mass function is adopted. We compare these results to theories describing the interaction between baryons and DM in cluster cores, including adiabatic contraction models and the possible effects of galaxy mergers and active galactic nucleus feedback, and evaluate possible signatures of alternative DM candidates.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1973

Trace elements in fines from the Apollo 15 deep drill.

Samples of fines from the bottom of the Apollo 15 deep drill core and from each junction between the six 42.5-cm long segments of the drill stem were analyzed for Ag, Co, Cr, Cs, Cu, Ga, Hf, Rb, Sc, and Zn by neutron activation. The most striking feature of the results is the absence of significant variations in concentration for any element throughout the depth of the drill sample and despite the considerable stratigraphy of the cored material. The presence of a significant amount of KREEP material is indicated.

Helmke, P. A.↗