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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

pyTCR: A tropical cyclone rainfall model for python

pyTCR is a climatology software package developed in the Python programming language. It integrates the capabilities of several legacy physical models and increases computational efficiency to allow rapid estimation of tropical cyclone (TC) rainfall consistent with the large-scale environment. Specifically, pyTCR implements a horizontally distributed and vertically integrated model [Zhu et al., 2013] for simulating rainfall driven by TCs. Along storm tracks, rainfall is estimated by computing the cross-boundary-layer, upward water vapor transport caused by different mechanisms including frictional convergence, vortex stretching, large-scale baroclinic effect (i.e., wind shear), topographic forcing, and radiative cooling [Lu et al., 2018]. The package provides essential functionalities for modeling and interpreting spatio-temporal TC rainfall data. pyTCR requires a limited number of model input parameters, making it a convenient and useful tool for analyzing rainfall mechanisms driven by TCs. To sample rare (most intense) rainfall events that are often of great societal interest, pyTCR adapts and leverages outputs from a statistical-dynamical TC downscaling model [Lin et al., 2023] capable of rapidly generating a large number of synthetic TCs given a certain climate. As a result, pyTCR significantly reduces computational effort and improves the efficiency in capturing extreme TC rainfall events at the tail of the distributions from limited datasets. Furthermore, the TC downscaling model is forced entirely by large-scale environmental conditions from reanalysis data or coupled General Circulation Models (GCMs), simplifying the projection of TC-induced rainfall and wind speed under future climate using pyTCR. Finally, pyTCR can be coupled with hydrological and wind models to assess risks associated with independent and compound events (e.g., storm surges and freshwater flooding).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Classification Analysis of Southwest Pacific Tropical Cyclone Intensity Changes Prior to Landfall

This study evaluates the ability of a random forest classifier to identify tropical cyclone (TC) intensification or weakening prior to landfall over the western region of the Southwest Pacific Ocean (SWPO) basin. For both Australia mainland and SWPO island cases, when a TC first crosses land after spending ≥24 h over the ocean, the closest hour prior to the intersection is considered as the landfall hour. If the maximum wind speed (V max ) at the landfall hour increased or remained the same from the 24-h mark prior to landfall, the TC is labeled as intensifying and if the V max at the landfall hour decreases, the TC is labeled as weakening. Geophysical and aerosol variables closest to the 24 h before landfall hour were collected for each sample. The random forest model with leave-one-out cross validation and the random oversampling example technique was identified as the best-performing classifier for both mainland and island cases. The model identified longitude, initial intensity, and sea skin temperature as the most important variables for the mainland and island landfall classification decisions. Incorrectly classified cases from the test data were analyzed by sorting the cases by their initial intensity hour, landfall hour, monthly distribution, and 24-h intensity changes. TC intensity changes near land strongly impact coastal preparations such as wind damage and flood damage mitigations; hence, this study will contribute to improve identifying and prioritizing prediction of important variables contributing to TC intensity change before landfall.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Future North Atlantic tropical cyclone intensities in thermodynamically modified historical environments

Tropical cyclones (TCs) rank as the deadliest and most financially crippling natural disasters in the United States for the last half-century. It is imperative to assess potential shifts in TC intensity within the paradigm of an evolving climate. In this study, we have modeled the intensities of 620 historical TC events in the North Atlantic Basin using the Risk Analysis Framework for Tropical Cyclones (RAFT)'s deep learning intensity model. By applying a thermodynamic warming signal extrapolated from Global Climate Models, we rerun historical events under eight different future climate scenarios, providing a spectrum of potential TC intensity outcomes. One of the future simulations indicates a staggering 43% increase in the number of major hurricanes, underscoring the critical impact of climate change on TC intensity. Additionally, an interactive dashboard has been created to enable users to explore individual storm simulations and understand the influence of future climate signals on environmental conditions of TC development and resulting TC intensities. This dataset and the user-friendly tool offer invaluable resources for systematic exploration of the discrete effects that changes in the air-sea thermodynamic state have on the intensities of TCs.

Climate Change↗
DOE OSTI2023

AGR-5/6/7 Thermal Model with Non-uniform Gas Gaps

Fuel compact temperatures are a crucial factor in assessing the irradiation performance of tri-structural isotropic fuel particles. In the absence of direct measurement, fuel compact temperatures were calculated using a three-dimensional finite element thermal model, which is subject to simulation uncertainty. The most dominant factor in the uncertainty of calculated fuel temperatures is the gas gap uncertainty due to the nub-to-shell clearance caused by a design error of AGR-5/6/7 capsules. The thermal model was revised to examine the most probable graphite offset position for six different days during the irradiation for Capsules 1 and 2. The analysis varied the offset distance and azimuthal direction at both the top and bottom of the holder. The best-fit offset was estimated based on the minimum root mean square error of the residuals (measured minus calculated) for the operational thermocouples (TCs). From these results, the following conclusions were made: (1) The holder offsets led to slightly lower average temperatures but wider temperature variations (lower minimum and higher peak fuel temperatures) for both Capsule 1 and Capsule 2. (2) During earlier cycles (162A–164B), when numerous TCs were still operational, the best-fit offset distance varied over a specific range for both the top and bottom ([0.002–0.0035 in.] for Capsule 1 and [0.003-0.004 in] for Capsule 2). In contrast, the offset azimuthal direction varied widely, especially for the offset at the bottom of the Capsule 1 holder. This is because holder movement was somewhat constrained at the top of Capsule 1 by the TC leads running through the capsule head and into the holder and by the through tubes in Capsule 2, but the Capsule 1 bottom did not have this type of constraint. (3) During later cycles, when all TCs failed, applying the maximum possible offset of 0.006 in. to the northwest direction for both the top and bottom resulted in a calculated peak fuel temperature of 1557? in Capsule 1 (i.e., a 135? increase from 1422? with zero offset on September 20, 2019 (166A)); the maximum offset of 0.0068 in. to the south for both top and bottom resulted in a calculated peak fuel temperature of 1110°C in Capsule 2 on April 20, 2020 (i.e., a 116? increase from 994? with zero offset (168A)). High peak fuel temperatures in Capsule 1 during Cycle 166A could be the cause of massive particle failure near the end of this cycle. (4) Even though the highest temperature at the tip of Type-N TCs, such as TC-1-7, slightly exceeded 1000?, the temperature along the TC wire reached as high as 1335? assuming an offset of 0.006 in. in the northwest of Capsule 1 holder near the end of Cycle 166A. This temperature significantly exceeds the temperature threshold at which TC degradation is expected to occur, ultimately contributing to considerable particle failures in Capsule 1. For eight Type-N TCs in Capsule 2, the peak TC line temperature was much lower (i.e., 1029°C for TC-2-5), assuming maximum offset of 00068 in. to the south during cycle 168A.

advanced gas reactors↗
DOE OSTI2023

AGR-5/6/7 Thermal Model with Non-uniform Gas Gaps

Fuel compact temperatures are a crucial factor in assessing the irradiation performance of tri-structural isotropic fuel particles. In the absence of direct measurement, fuel compact temperatures were calculated using a three-dimensional finite element thermal model, which is subject to simulation uncertainty. The most dominant factor in the uncertainty of calculated fuel temperatures is the gas gap uncertainty due to the nub-to-shell clearance caused by a design error of AGR-5/6/7 capsules. The thermal model was revised to examine the most probable graphite offset position for six different days during the irradiation for Capsules 1 and 2. The analysis varied the offset distance and azimuthal direction at both the top and bottom of the holder. The best-fit offset was estimated based on the minimum root mean square error of the residuals (measured minus calculated) for the operational thermocouples (TCs). From these results, the following conclusions were made: (1) The holder offsets led to slightly lower average temperatures but wider temperature variations (lower minimum and higher peak fuel temperatures) for both Capsule 1 and Capsule 2. (2) During earlier cycles (162A–164B), when numerous TCs were still operational, the best-fit offset distance varied over a specific range for both the top and bottom ([0.002–0.0035 in.] for Capsule 1 and [0.003-0.004 in] for Capsule 2). In contrast, the offset azimuthal direction varied widely, especially for the offset at the bottom of the Capsule 1 holder. This is because holder movement was somewhat constrained at the top of Capsule 1 by the TC leads running through the capsule head and into the holder and by the through tubes in Capsule 2, but the Capsule 1 bottom did not have this type of constraint. (3) During later cycles, when all TCs failed, applying the maximum possible offset of 0.006 in. to the northwest direction for both the top and bottom resulted in a calculated peak fuel temperature of 1557? in Capsule 1 (i.e., a 135? increase from 1422? with zero offset on September 20, 2019 (166A)); the maximum offset of 0.0068 in. to the south for both top and bottom resulted in a calculated peak fuel temperature of 1110°C in Capsule 2 on April 20, 2020 (i.e., a 116? increase from 994? with zero offset (168A)). High peak fuel temperatures in Capsule 1 during Cycle 166A could be the cause of massive particle failure near the end of this cycle. (4) Even though the highest temperature at the tip of Type-N TCs, such as TC-1-7, slightly exceeded 1000?, the temperature along the TC wire reached as high as 1335? assuming an offset of 0.006 in. in the northwest of Capsule 1 holder near the end of Cycle 166A. This temperature significantly exceeds the temperature threshold at which TC degradation is expected to occur, ultimately contributing to considerable particle failures in Capsule 1. For eight Type-N TCs in Capsule 2, the peak TC line temperature was much lower (i.e., 1029°C for TC-2-5), assuming maximum offset of 00068 in. to the south during cycle 168A.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

AGR-5/6/7 Thermal Model with Non-uniform Gas Gaps

Fuel compact temperatures are a crucial factor in assessing the irradiation performance of tri-structural isotropic fuel particles. In the absence of direct measurement, fuel compact temperatures were calculated using a three-dimensional finite element thermal model, which is subject to simulation uncertainty. The most dominant factor in the uncertainty of calculated fuel temperatures is the gas gap uncertainty due to the nub-to-shell clearance caused by a design error of AGR-5/6/7 capsules. The thermal model was revised to examine the most probable graphite offset position for six different days during the irradiation for Capsules 1 and 2. The analysis varied the offset distance and azimuthal direction at both the top and bottom of the holder. The best-fit offset was estimated based on the minimum root mean square error of the residuals (measured minus calculated) for the operational thermocouples (TCs). From these results, the following conclusions were made: (1) The holder offsets led to slightly lower average temperatures but wider temperature variations (lower minimum and higher peak fuel temperatures) for both Capsule 1 and Capsule 2. (2) During earlier cycles (162A–164B), when numerous TCs were still operational, the best-fit offset distance varied over a specific range for both the top and bottom ([0.002–0.0035 in.] for Capsule 1 and [0.003-0.004 in] for Capsule 2). In contrast, the offset azimuthal direction varied widely, especially for the offset at the bottom of the Capsule 1 holder. This is because holder movement was somewhat constrained at the top of Capsule 1 by the TC leads running through the capsule head and into the holder and by the through tubes in Capsule 2, but the Capsule 1 bottom did not have this type of constraint. (3) During later cycles, when all TCs failed, applying the maximum possible offset of 0.006 in. to the northwest direction for both the top and bottom resulted in a calculated peak fuel temperature of 1557? in Capsule 1 (i.e., a 135? increase from 1422? with zero offset on September 20, 2019 (166A)); the maximum offset of 0.0068 in. to the south for both top and bottom resulted in a calculated peak fuel temperature of 1110°C in Capsule 2 on April 20, 2020 (i.e., a 116? increase from 994? with zero offset (168A)). High peak fuel temperatures in Capsule 1 during Cycle 166A could be the cause of massive particle failure near the end of this cycle. (4) Even though the highest temperature at the tip of Type-N TCs, such as TC-1-7, slightly exceeded 1000?, the temperature along the TC wire reached as high as 1335? assuming an offset of 0.006 in. in the northwest of Capsule 1 holder near the end of Cycle 166A. This temperature significantly exceeds the temperature threshold at which TC degradation is expected to occur, ultimately contributing to considerable particle failures in Capsule 1. For eight Type-N TCs in Capsule 2, the peak TC line temperature was much lower (i.e., 1029°C for TC-2-5), assuming maximum offset of 00068 in. to the south during cycle 168A.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Materials Data on Al6Tc by Materials Project

TcAl6 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tc is bonded in a distorted q6 geometry to ten Al atoms. There are a spread of Tc–Al bond distances ranging from 2.52–2.67 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tc and nine Al atoms. There are a spread of Al–Al bond distances ranging from 2.69–2.96 Å. In the second Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tc and eight Al atoms. All Al–Al bond lengths are 2.97 Å. In the third Al site, Al is bonded in a 1-coordinate geometry to one Tc and ten Al atoms. There are one shorter (2.53 Å) and one longer (2.70 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U4Si6Tc7 by Materials Project

U4Tc7Si6 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. U+3.25+ is bonded in a hexagonal planar geometry to six equivalent Tc3- atoms. All U–Tc bond lengths are 2.91 Å. There are two inequivalent Tc3- sites. In the first Tc3- site, Tc3- is bonded to four equivalent U+3.25+, four equivalent Tc3-, and four equivalent Si+1.33+ atoms to form distorted TcU4Si4Tc4 cuboctahedra that share corners with four equivalent TcU4Si4Tc4 cuboctahedra, corners with four equivalent TcSi6 octahedra, edges with eight equivalent TcU4Si4Tc4 cuboctahedra, and faces with six equivalent TcU4Si4Tc4 cuboctahedra. The corner-sharing octahedral tilt angles are 53°. All Tc–Tc bond lengths are 2.91 Å. All Tc–Si bond lengths are 2.58 Å. In the second Tc3- site, Tc3- is bonded to six equivalent Si+1.33+ atoms to form corner-sharing TcSi6 octahedra. All Tc–Si bond lengths are 2.55 Å. Si+1.33+ is bonded in a 5-coordinate geometry to five Tc3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTc2Pd by Materials Project

LiTc2Pd is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Li is bonded in a distorted body-centered cubic geometry to eight equivalent Tc and six equivalent Pd atoms. All Li–Tc bond lengths are 2.64 Å. All Li–Pd bond lengths are 3.05 Å. Tc is bonded in a body-centered cubic geometry to four equivalent Li and four equivalent Pd atoms. All Tc–Pd bond lengths are 2.64 Å. Pd is bonded in a 8-coordinate geometry to six equivalent Li and eight equivalent Tc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTcPd by Materials Project

TcMnPd is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Tc is bonded to four equivalent Mn and six equivalent Pd atoms to form distorted TcMn4Pd6 tetrahedra that share corners with four equivalent PdMn4Tc6 tetrahedra, corners with six equivalent TcMn4Pd6 tetrahedra, edges with six equivalent PdMn4Tc6 tetrahedra, and faces with twelve equivalent TcMn4Pd6 tetrahedra. All Tc–Mn bond lengths are 2.51 Å. All Tc–Pd bond lengths are 2.89 Å. Mn is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Pd atoms. All Mn–Pd bond lengths are 2.51 Å. Pd is bonded to six equivalent Tc and four equivalent Mn atoms to form distorted PdMn4Tc6 tetrahedra that share corners with four equivalent TcMn4Pd6 tetrahedra, corners with six equivalent PdMn4Tc6 tetrahedra, edges with six equivalent TcMn4Pd6 tetrahedra, and faces with twelve equivalent PdMn4Tc6 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnTcMo by Materials Project

MoTcZn is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mo is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Zn atoms. All Mo–Tc bond lengths are 2.59 Å. All Mo–Zn bond lengths are 2.59 Å. Tc is bonded to four equivalent Mo and six equivalent Zn atoms to form distorted TcZn6Mo4 tetrahedra that share corners with four equivalent ZnTc6Mo4 tetrahedra, corners with six equivalent TcZn6Mo4 tetrahedra, edges with six equivalent ZnTc6Mo4 tetrahedra, and faces with twelve equivalent TcZn6Mo4 tetrahedra. All Tc–Zn bond lengths are 2.99 Å. Zn is bonded to four equivalent Mo and six equivalent Tc atoms to form distorted ZnTc6Mo4 tetrahedra that share corners with four equivalent TcZn6Mo4 tetrahedra, corners with six equivalent ZnTc6Mo4 tetrahedra, edges with six equivalent TcZn6Mo4 tetrahedra, and faces with twelve equivalent ZnTc6Mo4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CaTaTc by Materials Project

CaTaTc is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Ca is bonded in a 10-coordinate geometry to four equivalent Ta and six equivalent Tc atoms. All Ca–Ta bond lengths are 2.78 Å. All Ca–Tc bond lengths are 3.21 Å. Ta is bonded in a body-centered cubic geometry to four equivalent Ca and four equivalent Tc atoms. All Ta–Tc bond lengths are 2.78 Å. Tc is bonded in a 10-coordinate geometry to six equivalent Ca and four equivalent Ta atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnAlTc by Materials Project

TcMnAl is half-Heusler structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Tc is bonded in a 4-coordinate geometry to six equivalent Mn and four equivalent Al atoms. All Tc–Mn bond lengths are 2.91 Å. All Tc–Al bond lengths are 2.52 Å. Mn is bonded in a 10-coordinate geometry to six equivalent Tc and four equivalent Al atoms. All Mn–Al bond lengths are 2.52 Å. Al is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaTcPb2 by Materials Project

TaTcPb2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Ta is bonded in a distorted body-centered cubic geometry to four equivalent Tc and ten Pb atoms. There are a spread of Ta–Tc bond distances ranging from 2.99–3.04 Å. There are a spread of Ta–Pb bond distances ranging from 3.02–3.50 Å. Tc is bonded in a distorted body-centered cubic geometry to four equivalent Ta and four equivalent Pb atoms. There are one shorter (3.01 Å) and three longer (3.02 Å) Tc–Pb bond lengths. There are two inequivalent Pb sites. In the first Pb site, Pb is bonded to six equivalent Ta, four equivalent Tc, and four equivalent Pb atoms to form a mixture of distorted face and corner-sharing PbTa6Tc4Pb4 tetrahedra. All Pb–Pb bond lengths are 3.02 Å. In the second Pb site, Pb is bonded to four equivalent Ta and four equivalent Pb atoms to form distorted PbTa4Pb4 tetrahedra that share corners with twelve equivalent PbTa6Tc4Pb4 tetrahedra, edges with twelve equivalent PbTa4Pb4 tetrahedra, and faces with four equivalent PbTa6Tc4Pb4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ti2AlTc by Materials Project

Ti2TcAl is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ti is bonded in a body-centered cubic geometry to four equivalent Tc and four equivalent Al atoms. All Ti–Tc bond lengths are 2.72 Å. All Ti–Al bond lengths are 2.72 Å. Tc is bonded in a distorted body-centered cubic geometry to eight equivalent Ti and six equivalent Al atoms. All Tc–Al bond lengths are 3.14 Å. Al is bonded in a distorted body-centered cubic geometry to eight equivalent Ti and six equivalent Tc atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ErThTc2 by Materials Project

ThErTc2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Th is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Th–Tc bond lengths are 3.00 Å. Er is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Er–Tc bond lengths are 3.00 Å. Tc is bonded in a body-centered cubic geometry to four equivalent Th and four equivalent Er atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoThTc2 by Materials Project

ThHoTc2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Th is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Th–Tc bond lengths are 3.00 Å. Ho is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Ho–Tc bond lengths are 3.00 Å. Tc is bonded in a body-centered cubic geometry to four equivalent Th and four equivalent Ho atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfPaTc2 by Materials Project

PaHfTc2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Pa–Tc bond lengths are 2.91 Å. Hf is bonded in a body-centered cubic geometry to eight equivalent Tc atoms. All Hf–Tc bond lengths are 2.91 Å. Tc is bonded in a body-centered cubic geometry to four equivalent Pa and four equivalent Hf atoms.

36 MATERIALS SCIENCE↗