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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 217 records · Page 12

Corrosion sensitivity of nickel-based Alloy Inconel 600 in pressurized water reactor water chemistry: Can KOH replace LiOH?

Lithium hydroxide (LiOH) has been used to balance water acidity against boric acid moderators in the primary water of Western pressurized water reactor (PWR) designs for decades. However, the demand and the cost of lithium-7 has grown significantly since 2015. Potassium hydroxide (KOH) has been identified as a suitable and cost-effective substitute for LiOH and has been used successfully in Russian PWR designs for more than 40 years. However, it is important to know if alloys and water conditions used in Western PWR’s (Alloy 600) are similarly compatible with KOH additions. This work is focused on the aqueous corrosion behaviors of Alloy 600 with LiOH versus KOH additions at normal operating concentrations and crevice water chemistry at simulated PWR primary water conditions. TEM was used to characterize the formed oxide through diffraction analysis; SIMS was used to probe the cation ingress into the material; Atom probe tomography was used to determine the 3D elemental distribution within the oxide/metal structures; finally electrochemical impedance spectroscopy was used to discuss the structure and corrosion resistance of the oxide films. These advanced characterization techniques complement the weight measurments which showed lower mass gain in KOH than LiOH crevice water due to less oxide formation. Overall, the use of KOH as a potential alternative to LiOH in PWR is discussed.

Alloy 600↗

A Novel Surface Restoration Method for Hydropower Steel Components: Plasma Gouging and Inconel Cold Spray Coating for Material Repair

A novel surface restoration approach combining plasma gouging with subsequent cold spray deposition is demonstrated in this study. Plasma gouging effectively removes the damaged steel surface, leaving grooves and forming a plasma gouging affected zone up to ~300?µm thick. Within this zone, a hardened martensitic layer with a peak hardness of ~370?HV—almost twice that of the base substrate (~200?HV)—is produced. Following plasma gouging, cold spray deposition is applied to rebuild the surface. Experimental results reveal that cold spray coatings deposited at low energy suffer from delamination, whereas high energy cold spray deposits yield a well-bonded coating. Microstructural analysis further shows that the martensitic layer formed by plasma gouging undergoes dynamic recrystallization during cold spray, reducing the hardness to 317?HV. These findings demonstrate the feasibility of this hybrid method for effective surface restoration of damaged steel components.

Wang, Tianhao↗

Exploring the Feasibility of INCONEL® ALLOY 740H® for Power Plant Headers: Integrating Machine Learning with Computational Fluid Dynamics (CFD)

This keynote presentation explores the behavior of headers—essential components of pipeline systems—using ANSYS simulation software and machine learning techniques. The study aims to predict the thermal and mechanical performance of headers under diverse conditions through both steady-state and transient simulations. We investigate critical parameters such as heat transfer coefficient, fluid velocity, and temperature to optimize header design. Conducted as part of a DOE project led by NCAT in collaboration with UNC Charlotte, this research encompasses multiple key topics. The initial section focuses on the behavior of header systems under steady-state conditions using ANSYS simulation. It underscores the importance of headers in industrial infrastructure, especially in the energy sector, and examines the implications of material selection and flow direction on heat transfer dynamics. Methodologically, we employ Computational Fluid Dynamics (CFD) analysis through ANSYS, detailing the development of models, material properties, geometry specifications, boundary conditions, and meshing strategies. Our simulations explore various operational parameters, including temperature and mass flow rates, crucial for predicting heat transfer coefficients and enhancing header design. Results from the study include parametric investigations into mesh sensitivity, viscosity model evaluations, and the effects of heat transfer locations, all validated against theoretical calculations. We conclude with insights on mesh optimization, the suitability of viscosity models, and recommendations for future research aimed at improving header system efficiency and sustainability in industrial applications.

20 FOSSIL-FUELED POWER PLANTS↗

In-Plane Liftout and Push-to-Pull for In Situ Mechanical Testing of Irradiated Inconel X-750

A streamlined sample preparation method for nanomechanical testing is needed to improve the quality of specimens, reduce the cost, and increase the versatility of specimen fabrication. This work outlines an in-plane liftout focused ion beam (FIB) fabrication procedure to prepare electron-transparent specimens for in situ transmission electron microscopy (TEM) nanomechanical testing. Ion etching and electron backscatter diffraction (EBSD) techniques were used to lift out a [110] oriented grain from a neutron-irradiated bulk X-750 alloy. Careful control of voltages and currents ensured precision. Top surface thinning sweeps prevented resurfacing and redeposition while dog-bone geometries were shaped with a 1:4 gauge width-to-milling pattern diameter ratio. Nanotensile testing in the TEM with a picoindenter allowed for the estimation of an ultimate tensile strength of 2.41 GPa, and inspection revealed a high density of bubbles in the X-750 matrix. The proposed fabrication procedure is significant for preparing samples from radioactive materials, studying complex structures that are orientation-dependent, and analyzing desired planar areas.

36 MATERIALS SCIENCE↗