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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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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Whisper Sensitivity Study of the NMIS ATR Fuel Storage Racks

A sensitivity study was performed on the NMIS ATR fuel storage racks as part of the CSE to implement the boron-carbide aluminum composite shelves. Whisper was used as part of this study to find applicable benchmarks for validation purposes. It was found that Whisper is very useful in finding benchmarks for the most sensitive isotopes in a problem but can be used to search for sensitivities related to specific isotopes. Whisper gave confidence in the NMIS validation and helped the author learn details about the physics of the problem as well.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2018

Experimental Investigation of the System Nonmetallic Inclusion-Molten Steel-Refractory System at High Temperatures

In continuous casting, the buildup of particles in the flow control system is called clogging. Clogging may be caused by preexisting nonmetallic inclusions attached to the refractory wall, interrupting or disturbing the fluid flow conditions. The interfacial properties of the nonmetallic inclusion-molten steel-refractory system are believed to play a key role in the clogging tendency of selected steel grades in contact with ceramics. The combination of a high-temperature laser scanning confocal microscope (HT-LSCM), which is employed for in situ observation of inclusions’ behavior in the liquid steel or at the steel/ceramic interface, and a high-temperature drop shape analyzer (HT-DSA), which is utilized for contact angle measurements, enabled the investigation of reactions and interactions in the described system at experimental temperatures of approximately 1600 °C. The objective of this study was to develop a method to obtain qualitative information on the deposition of nonmetallic inclusions (NMIs) in the submerged entry nozzle (SEN) during casting. The behavior of solid NMIs from a calcium-treated steel at the interface between liquid steel and Al{sub 2}O{sub 3} or MgO was investigated by means of HT-LSCM. During the test evaluation, inclusions were found to separate at the steel/ceramic interface due to an attractive force. This force increased with the NMIs’ size as well as with the ceramic particle change. The HT-DSA provided contact angle data between molten steel and the ceramic used for implementation into the theoretical capillary force model. A clear correspondence between the estimated and calculated capillary forces was observed. The change in the wettability of the system, as induced by the change in the ceramic from MgO to Al{sub 2}O{sub 3}, showed a reduction of the attractive forces, indicating a weaker separation toward the SEN for the same inclusion type. This study confirmed the strong potential of wettability investigations to predict the clogging tendency of certain steel grades.

36 MATERIALS SCIENCE↗
DOE OSTI2017

NMIS/FNMIS Comparison for US DOE Office of Nuclear Verification

A comparison of the characteristics of the Nuclear Materials Identification System (NMIS) and its more fieldable version that was developed for future treaty applications, the Fieldable Nuclear Materials Identification System (FNMIS), is presented. Both systems were developed for the US Department of Energy (DOE) Office of Nuclear Verification (ONV). Under the Warhead Safety and Security Exchange Agreement, NMIS was also jointly developed with the Russian Federation. The configuration of the systems and their characteristics are described. In addition, the capabilities, advantages and disadvantages, and a comparison fast-neutron transmission imaging measurement is presented. The comparison measurements gave essentially the same results because the software and imaging apparatus have the same capabilities, with the FNMIS completing the measurements slightly faster. NMIS is an open system that is more easily modified for research applications and is not suitable for the ONV mission, and FNMIS is compatible with an information barrier, which is more useful for ONV applications.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2018

Fluid Force-Induced Detachment Criteria for Nonmetallic Inclusions Adhered to a Refractory/Molten Steel Interface

Since nonmetallic inclusions (NMIs) in steel cannot be completely avoided, a greater understanding of their development and evolution during the steelmaking process is required. In particular, this includes the adhesion of microinclusions to the refractory/steel interface in the flow control system between the tundish and the mold. This phenomenon, commonly referred to as clogging, causes losses in productivity and product quality. Inclusions transported from the bulk melt to the boundary layer may adhere to the refractory/steel interface due to formation of a fluid cavity. A detailed model was derived for the detachment of NMIs adhering to a nozzle wall and is based on the local hydrodynamic conditions combined with the specific interfacial properties in the system consisting of the inclusions, the refractories, and the steel. The model is evaluated for three different application-oriented cases. This study has been focused on providing a better understanding of fluid flow in the near-wall region in order to reduce clogging during steelmaking.

42 ENGINEERING↗
DOE OSTI2019

Characterization of Nonmetallic Inclusions in 18CrNiMo7-6

The detrimental effect of nonmetallic inclusions (NMIs) in steels on, e.g., fatigue lifetime is well known. In order to increase the durability and safety of materials and components, inclusion control and a deep understanding of inclusion formation are essential. The present study examines the formation of inclusions as well as their content, type, morphology, and size distribution for different batches of the steel alloy 18CrNiMo7-6 (AISI 4317), which was processed with various refractory crucible materials. To this end, extensive metallographic investigations were carried out including fracture surface analyses, metallographic sections, and the chemical extraction of inclusions. Scanning electron microscopy supported by energy-dispersive X-ray spectroscopy was used alongside electron backscatter diffraction for the qualitative and quantitative analysis of the NMIs. Oxide contents were found to have a significant effect on sulfide precipitation behavior, and had a strong impact on the resulting sizes and numbers of inclusions. The formation and growth of sulfides and oxide-sulfides featuring different morphologies is discussed on the basis of these experimental results.

36 MATERIALS SCIENCE↗