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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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7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Influence of Joule Heating on the Stability of High Temperature Irradiation Resistant Thermocouples

Development of in-core instrumentation is driven by the pursuit of safer and more economic energy production from both existing nuclear reactors and Generation IV reactor designs. Idaho National Laboratory (INL) has developed high temperature irradiation resistant thermocouples (HTIR-TCs) for temperature sensing inside Generation IV nuclear reactors. These thermocouples are composed of phosphorus-doped niobium (Nb-P) and lanthana-doped molybdenum (Mo-LaO) thermoelements, an alumina (Al2O3) insulation, and a niobium sheath. HTIR-TCs require an initial heat treatment exceeding the maximum service temperature to stabilize the generated electromotive force (EMF) signal; however, the mechanism behind this stabilization is not well understood. This work evaluates the impact of Joule heating on the thermoelements' microstructures, chemical stability, and mechanical properties to determine the mechanisms by which the EMF signal stabilization occurs. Accordingly, during the Joule heat treatment, a secondary Nb3P phase coarsened along the length of the Nb-P thermoelement, along with the formation of an interaction region at the Al2O3/niobium interface. The interaction between the alumina insulation and the Nb-P thermoelement was also observed within the Mo-LaO thermoelement. Joule heating induced stability within the generated EMF signal of HTIR-TCs through the formation of secondary phases within the Nb-P and the interaction of the alumina insulation with the thermoelements.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
DOE OSTI2024

Influence of Joule Heating on the Stability of High Temperature Irradiation-resistant Thermocouples

Development of in-core instrumentation is driven by the pursuit of safer, more economic energy production from the perspective of both existing nuclear reactors and Generation IV reactor designs. Idaho National Laboratory has developed high-temperature irradiation-resistant thermocouples (HTIR-TCs) for temperature sensing inside Generation IV nuclear reactors. These thermocouples are composed of phosphorus-doped niobium (Nb-P) and lanthana-doped molybdenum (Mo-LaO) thermoelements, an alumina (Al2O3) insulation, and a niobium sheath. HTIR-TCs require an initial heat treatment exceeding the maximum service temperature to stabilize the generated electromotive force (EMF) signal. The mechanism behind the stabilization of the HTIR-TCs through traditional heat treatment methods is understood; however, the traditional heat treatment method is expensive, time consuming, and results in a heterogeneous microstructure. Therefore, we investigated a rapid method for stabilization and microstructure homogeneity, through Joule heating. This work evaluates the impact of Joule heating on the thermoelements’ microstructures, chemical stability, and mechanical properties so as to determine the mechanisms by which stabilization of the EMF signal occurs. Accordingly, during the Joule heat treatment, a secondary Nb3P phase coarsened along the length of the Nb-P thermoelement, along with the formation of an interaction region at the Al2O3/niobium interface. The interaction between the alumina insulation and the Nb-P thermoelement was also observed within the Mo-LaO thermoelement. Joule heating induced stability within the generated HTIR-TC EMF signal via the formation of secondary phases within the Nb-P and the interaction between the alumina insulation and the thermoelements.

46 - INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AN↗
DOE OSTI2021

Self-Assembled Thermoresponsive Molecular Brushes as Nanoreactors for Asymmetric Aldol Addition in Water

The manipulation and tunability of self-assembled block copolymers through external stimuli presents an attractive strategy to develop smart polymer-based nanoreactors as supports for non-orthogonal tandem catalysis. We report on thermoresponsive core-shell micelles based on poly[norbornene-poly(2-methyl-2-oxazoline-block-2-propyl-2-oxazoline)]-graft-poly[norbornene L-proline] (P[NB-P(MeOx-b-PropOx)]-graft-P[NB-L-proline]) as catalyst supports for L-proline. These molecular brushes exhibit large differences in lower critical solution temperature behavior and nanostructure size in water depending on the chain-lengths and proline connectivity. L-Proline-mediated aldol reactions expose the efficiency by which the molecular brushes self-assemble into micelles. Molecular brushes with an extended backbone show higher activity and selectivity, suggesting better core-shell segregation of the micelles and exclusion of water from the catalytic site. Catalytic efficiencies are not improved above the cloud point temperature, the catalytic be-havior is rather sensitive to conformational changes of the polymer chains.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Nb7P4 by Materials Project

Nb7P4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are eight inequivalent Nb sites. In the first Nb site, Nb is bonded in a 4-coordinate geometry to five P atoms. There are a spread of Nb–P bond distances ranging from 2.58–3.01 Å. In the second Nb site, Nb is bonded to five P atoms to form a mixture of distorted face, edge, and corner-sharing NbP5 trigonal bipyramids. There are a spread of Nb–P bond distances ranging from 2.50–2.59 Å. In the third Nb site, Nb is bonded in a 5-coordinate geometry to five P atoms. There are a spread of Nb–P bond distances ranging from 2.60–2.91 Å. In the fourth Nb site, Nb is bonded to five P atoms to form a mixture of distorted face, edge, and corner-sharing NbP5 trigonal bipyramids. There are a spread of Nb–P bond distances ranging from 2.46–2.62 Å. In the fifth Nb site, Nb is bonded in a 4-coordinate geometry to four P atoms. There are a spread of Nb–P bond distances ranging from 2.48–2.73 Å. In the sixth Nb site, Nb is bonded in a 4-coordinate geometry to five P atoms. There are a spread of Nb–P bond distances ranging from 2.60–3.05 Å. In the seventh Nb site, Nb is bonded in a square co-planar geometry to four P atoms. There are two shorter (2.61 Å) and two longer (2.65 Å) Nb–P bond lengths. In the eighth Nb site, Nb is bonded in a distorted square co-planar geometry to four P atoms. There are two shorter (2.53 Å) and two longer (2.69 Å) Nb–P bond lengths. There are four inequivalent P sites. In the first P site, P is bonded in a 9-coordinate geometry to nine Nb atoms. In the second P site, P is bonded in a 9-coordinate geometry to nine Nb atoms. In the third P site, P is bonded to seven Nb atoms to form a mixture of distorted edge and corner-sharing PNb7 pentagonal bipyramids. In the fourth P site, P is bonded in a 8-coordinate geometry to eight Nb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb2P5 by Materials Project

Nb2P5 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are two inequivalent Nb+3.50+ sites. In the first Nb+3.50+ site, Nb+3.50+ is bonded in a 8-coordinate geometry to eight P+1.40- atoms. There are a spread of Nb–P bond distances ranging from 2.51–2.67 Å. In the second Nb+3.50+ site, Nb+3.50+ is bonded in a 8-coordinate geometry to eight P+1.40- atoms. There are a spread of Nb–P bond distances ranging from 2.54–2.70 Å. There are five inequivalent P+1.40- sites. In the first P+1.40- site, P+1.40- is bonded in a 5-coordinate geometry to five Nb+3.50+ atoms. In the second P+1.40- site, P+1.40- is bonded in a 5-coordinate geometry to five Nb+3.50+ atoms. In the third P+1.40- site, P+1.40- is bonded to one Nb+3.50+ and three P+1.40- atoms to form distorted corner-sharing PNbP3 tetrahedra. There are one shorter (2.17 Å) and two longer (2.25 Å) P–P bond lengths. In the fourth P+1.40- site, P+1.40- is bonded to two equivalent Nb+3.50+ and two P+1.40- atoms to form distorted corner-sharing PNb2P2 tetrahedra. The P–P bond length is 2.22 Å. In the fifth P+1.40- site, P+1.40- is bonded in a 4-coordinate geometry to three equivalent Nb+3.50+ and three P+1.40- atoms. Both P–P bond lengths are 2.64 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Nb3P by Materials Project

Nb3P crystallizes in the tetragonal P4_2/n space group. The structure is three-dimensional. there are three inequivalent Nb sites. In the first Nb site, Nb is bonded in a distorted bent 150 degrees geometry to two equivalent P atoms. There are one shorter (2.59 Å) and one longer (2.62 Å) Nb–P bond lengths. In the second Nb site, Nb is bonded in a 4-coordinate geometry to four equivalent P atoms. There are a spread of Nb–P bond distances ranging from 2.57–2.66 Å. In the third Nb site, Nb is bonded in a 2-coordinate geometry to three equivalent P atoms. There are a spread of Nb–P bond distances ranging from 2.56–2.91 Å. P is bonded in a 9-coordinate geometry to nine Nb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NbP by Materials Project

NbP is alpha Niobium phosphide structured and crystallizes in the tetragonal I4_1/amd space group. The structure is two-dimensional and consists of four NbP sheets oriented in the (0, 0, 1) direction. Nb3+ is bonded in a square co-planar geometry to four equivalent P3- atoms. All Nb–P bond lengths are 2.49 Å. P3- is bonded in a square co-planar geometry to four equivalent Nb3+ atoms.

36 MATERIALS SCIENCE↗