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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Optimization of heat treatment and calibration procedures for high temperature irradiation resistant thermocouples [The development of calibration procedures for high temperature irradiation resistant thermocouples]

Here, a detailed description is provided for the optimization of heat treatment and calibrating procedure for Idaho National Laboratory’s high temperature irradiation resistant thermocouples (HTIR-TC). Also discussed is the implication of the procedures on the overall performance of the HTIR-TC finished product; in particular, for the case of long lead sections that are typical of sensors deployed in nuclear reactors. The effect on the measurement accuracy of fluctuations of the reference temperature and localized heating along the sensor lead is also investigated. A calibration graphical user interface (GUI) and accompanying script is presented for unifying the calibration process. A fifth-order polynomial function was found to be best for fitting HTIR-TC calibration data. The performance of the HTIR-TCs subject to the optimized heat treatment and calibration procedures is shown to be robust and consistent with other TC industry standards. Electromotive force curves versus length of the TC are presented to clarify positioning of TCs in general and how its effect on the calibrated temperatures.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

SU-E-T-522: Investigation of Underdosage of Total Body Irradiation with Bilateral Irradiation Scheme

Purpose: Patient in-vivo measurements report lower readings than those predicted from TMR-based treatment planning on TBI patient knees and ankles where rice was placed to fill the gap between patient’s legs. This study is to understand and correct the under dosage of Total Body Irradiation(TBI) with rice tissue equivalent bolus placement at TBI treatment patient setup. Methods: Bilateral TBI scheme was investigated with rice bags bolus placing between patient’s two legs acting as missing tissue. In-house TMR based treatment planning system was commissioned with measurements under TBI condition at 10MV, i.e. source-to-reference distance 383.4cm with 40×40cm field size with 1cm thickness Lucite. Predictions of patient specific dose points are reported at different sites with 200cGy prescription at patient umbilicus point. Solid water and rice bag phantoms are used at TBI conditions for the attenuation factor verification and CT scanned to verify the CT number and electron density. Results: We found that the rice bag bolus overall density is 11% lower than the water; however, the attenuation factor of rice bags could become 15% lower than that of water at TBI condition. This overestimate of rice bag electron density could cause the lack of lateral scatter and the lack of backscatter. This could Result in an overestimate of dose at in-vivo dosimeter measurement points with TMR-based treatment planning systems. Observations of patient specific optically stimulated luminescent dosimeters(OSLDs) were used to confirm this overestimation. Measurements of setups with increasing the rice bag filled patient leg separation were performed to demonstrate eliminating the overdose issue. Conclusion: Rice bolus has a lower electron density than water does(11%) but results in 15% lower in attenuation factor at TBI condition. This effect was observed in patient delivery with OSLD measurements and can be corrected by increasing the filling rice bolus thickness with 15% longer of separation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Advanced electron microscopic techniques applied to the characterization of irradiation effects and fission product identification of irradiated TRISO coated particles from the AGR-1 experiment

Preliminary electron microscopy of coated fuel particles from the AGR-1 experiment was conducted using characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and wavelength dispersive spectroscopy (WDS). Microscopic quantification of fission-product precipitates was performed. Although numerous micro- and nano-sized precipitates observed in the coating layers during initial SEM characterization of the cross-sections, and in subsequent TEM diffraction patterns, were indexed as UPd{sub 2}Si{sub 2}, no Ag was conclusively found. Additionally, characterization of these precipitates highlighted the difficulty of measuring low concentrations of Ag in precipitates in the presence of significantly higher concentrations of Pd and U. The electron microscopy team followed a multi-directional and phased approach in the identification of fission products in irradiated TRISO fuel. The advanced electron microscopy techniques discussed in this paper, not only demonstrate the usefulness of the equipment (methods) as relevant research tools, but also provide relevant scientific results which increase the knowledge about TRISO fuel particles microstructure and fission products transport.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Using synchrotron X-ray phase-contrast micro-computed tomography to study tissue damage by laser irradiation: STUDY TISSUE DAMAGE BY LASER IRRADIATION

Background and Objective: The aim of this study was to determine if X-ray micro-computed tomography could be used to locate and characterize tissue damage caused by laser irradiation and to describe its advantages over classical histology for this application. Study Design/Materials and Methods: A surgical CO2 laser, operated in single pulse mode (100 milliseconds) at different power settings, was used to ablate different types of cadaveric animal tissues. Tissue samples were then harvested and imaged with synchrotron X-ray phasecontrast and micro-computed tomography to generate stacks of virtual sections of the tissues. Subsequently, Fiji (ImageJ) software was used to locate tissue damage, then to quantify volumes of laser ablation cones and thermal coagulation damage from 3D renderings of tissue image stacks. Visual comparisons of tissue structures in X-ray images with those visible by classic light microscopy histology were made. Results: We demonstrated that micro-computed tomography could be used to rapidly identify areas of surgical laser ablation, vacuolization, carbonization, and thermally coagulated tissue. Quantification and comparison of the ablation crater, which represents the volume of ablated tissue, and the thermal coagulation zone volumeswere performed faster than we could by classical histology. We demonstrated that these procedures can be performed on fresh hydrated and non-sectioned plastic embedded tissue. Conclusion: We demonstrated that the application of non-destructive micro-computed tomography to the visualization and analysis of laser induced tissue damage without tissue sectioning is possible. This will improve evaluation of new surgical lasers and their corresponding effect on tissues.

Ablation↗
DOE OSTI2019

GaAs/silicon PVMirror tandem photovoltaic mini‐module with 29.6% efficiency with respect to the outdoor global irradiance

Abstract Balance‐of‐system costs now dominate the installed cost of photovoltaic systems, causing the annually averaged module efficiency to become a primary system cost driver. The resulting continued push towards higher module efficiencies, coupled with the dominance of single‐axis tracking in the utility‐scale PV market, may create an opportunity for a low‐concentration tandem module technology. Here, we demonstrate such a tandem, using the “PVMirror” concept, on the mini‐module scale. The tandem couples a (concentrating) silicon PVMirror having an aperture area of 156.25 cm 2 with a gallium arsenide receiver to achieve 29.6% efficiency with respect to the outdoor global irradiance. Unlike most concentrating technologies, the silicon PVMirror collects some of the diffuse light, but the tandem would nevertheless achieve 31% efficiency in the absence of diffuse light, as in a laboratory measurement. The same tandem technology can be implemented with a wide‐bandgap thin‐film PVMirror and silicon receiver—a potentially cost‐competitive combination—when efficient wide‐bandgap cells have been developed.

Yu, Zhengshan J.↗
DOE OSTI2019

Ag–TiO 2 Hybrid Nanocrystal Photocatalyst: Hydrogen Evolution under UV Irradiation but Not under Visible-Light Irradiation

In this work, we report a thermolytic reduction of silver precursors in the presence of anatase TiO 2 nanorods to form Ag–TiO 2 hybrid nanocrystals (HNCs). Upon changing the reaction conditions, the size and number density of Ag on the HNCs could be adjusted. The size and number density of Ag on the HNCs were found to have an inverse relation. We assess the hydrogen evolution of TiO 2 nanorods, P25 TiO 2 , and Ag–TiO 2 HNCs in methanol/water under xenon lamp irradiation. The turnover frequency for hydrogen evolution on silica-supported Ag–TiO 2 was 1.4 × 10 –4 s –1 , greater than that of the anatase TiO 2 nanorods (9.8 × 10 –6 s –1 ) or the coupled anatase/rutile TiO 2 (P25 catalyst; 5.2 × 10 –5 s –1 ).

36 MATERIALS SCIENCE↗