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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

A Semantic Search Capability for a Grid Model Repository

The operation of electric grids is becoming more challenging due to continued increases in wind and solar generation, the proliferation of decentralization generation resources, and cyber security threats. To support the needed research, new large scale realistic public grid models have been developed and placed in a repository for access by researchers. To assist researchers in easily finding grid models that are suitable for their specific research needs, an approach to searching numerous large grid models was evaluated, prototyped and developed. Here, the research identified multiple possible approaches to using graph database techniques and a natural language processing for the search algorithm. Results of the prototype, the final approach for production repository and the search algorithm formulation are described.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

Mineral-specific heterogeneous neptunium sorption onto geological repository rocks in oxic and anoxic conditions and various temperatures

Neptunium poses challenges for radioactive wastes management due to its long half-life and ingrowth from americium decay, as well as its high mobility in water in its oxidized forms. Np(V)-bearing aqueous solutions were contacted with polished and crushed gneiss and dolerite from the Yeniseisky site, Russia, which is under consideration as a location for an underground repository, both in oxic and anoxic conditions at 20 and 90 °C. Neptunium sorption on crushed gneiss and dolerite in oxic conditions at 20 °C was quite low, but increased substantially in anoxic conditions. Autoradiography on samples treated at 20 °C revealed that sorbed Np was associated mostly with dark colored iron-bearing minerals, and solvent extraction indicated partial reduction of Np(V) to Np(IV). Sorption of Np from aqueous solutions contacted with dolerite and gneiss at 90 °C was in all cases higher than at the lower temperature. Autoradiography of polished rock samples treated in anoxic conditions at 90 °C revealed that Fe-bearing minerals had 3–4 orders of magnitude more Np sorbed on them than the quartz and feldspar grains. X-ray photoelectron spectroscopy indicated this sorbed Np was present as NpO 2 . This study supports the concept that the geologic conditions present at the planned repository site will retard Np migration.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Reduced-order modeling of near-field THMC coupled processes for nuclear waste repositories in shale

Performance assessment (PA) of geologic radioactive waste repositories requires three-dimensional simulation of highly nonlinear, thermo-hydro-mechanical-chemical (THMC), multiphase flow and transport processes across many kilometers and over tens to hundreds of thousands of years. Integrating the effects of a near-field geomechanical process (i.e. buffer swelling) into coupled THC simulations through reduced-order modeling, rather than through fully coupled geomechanics, can reduce the dimensionality of the problem and improve computational efficiency. In this study, PFLOTRAN simulations model a single waste package in a shale host rock repository, where re-saturation of a bentonite buffer causes the buffer to swell and exert stress on a highly fractured disturbed rock zone (DRZ). Three types of stress-dependent permeability functions (exponential, modified cubic, and Two-part Hooke’s law models) are implemented to describe mechanical characteristics of the system. Overall, our modeling study suggests that compressing fractures reduces DRZ permeability, which could influence the rate of radionuclide transport and exchange with corrosive species in host rock groundwater that could accelerate waste package degradation. Less permeable shale host rock delays buffer swelling, consequently retarding DRZ permeability reduction as well as chemical transport within the barrier system.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Machine Learning Surrogates of a Fuel Matrix Degradation Process Model for Performance Assessment of a Nuclear Waste Repository

Spent nuclear fuel repository simulations are currently not able to incorporate detailed fuel matrix degradation (FMD) process models due to their computational cost, especially when large numbers of waste packages breach. The current paper uses machine learning to develop artificial neural network and k-nearest neighbor regression surrogate models that approximate the detailed FMD process model while being computationally much faster to evaluate. Further, using fuel cask temperature, dose rate, and the environmental concentrations of CO 3 2- , O 2 , Fe 2+ , and H 2 as inputs, these surrogates show good agreement with the FMD process model predictions of the UO 2 degradation rate for conditions within the range of the training data. A demonstration in a full-scale shale repository reference case simulation shows that the incorporation of the surrogate models captures local and temporal environmental effects on fuel degradation rates while retaining good computational efficiency.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Science and Engineering Team Repository Selection and Validation

The National Nuclear Security Administration’s Office of Nuclear Smuggling Detection and Deterrence (NSDD), Science and Engineering Team (SET) has engaged Brookhaven National Laboratory (BNL) in the selection, development and management of a knowledge management platform. This platform will serve as a repository for programmatic documents, data, and other relevant files. In support of this effort, BNL implemented a sixteen-month process to ensure the selection of the most relevant and user-friendly repository from among several commercially available and open source options.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
NASA NTRSDate not supplied

SatCORPS Hybridized Cloud Product Data Storage: The Design of a Hybrid Data Repository That Leverages the Strengths of the Cloud and the Data Center

There is a strong demand for the near real time NASA Langley Satellite ClOud and Radiation Property retrieval System (SatCORPS) products. As important as real-time information, archived copies of the products form the basis for targeted research focusing on specific events or conditions. To make these SatCORPS products available for downloading, the SatCORPS group has developed a number of tools and technologies to create a hybrid data storage system that leverages the strengths of both cloud and on-premises resources. In this work, we describe the technologies the group uses to marshal disparate data repositories and materialize them into a single searchable overview and give a broad description of the organization of the dataset. As with any implementation, the strengths, weaknesses and constraints surrounding the components establish priorities and provide insight where trade-offs are necessary. We further describe the design and architecture underpinning our hybrid data repository and delivery system.

AWS↗
NASA NTRS2025

NASA Open Science Data Repository: Open Science for Life in Space

Space biology and health data are critical for the success of deep space missions and sustainable human presence off-world. At the core of effectively managing biomedical risks is the commitment to open science principles, which ensure that data are findable, accessible, interoperable, reusable, reproducible and maximally open. The 2021 integration of the Ames Life Sciences Data Archive with GeneLab to establish the NASA Open Science Data Repository significantly enhanced access to a wide range of life sciences, biomedical-clinical, and mission telemetry data alongside existing ‘omics data from GeneLab. This paper describes the new database, its architecture, and new data streams supporting diverse data types and enhancing data submission, retrieval, and analysis. Features include the Biological Data Management Environment for improved data submission, a new user interface, controlled data access, an enhanced API, and comprehensive public visualization tools for environmental telemetry, radiation dosimetry data, and ‘omics analyses. By fostering global collaboration through its Analysis Working Groups and training programs, the Open Science Data Repository promotes widespread engagement in space biology, ensuring transparency and inclusivity in research. It supports the global scientific community in advancing our understanding of spaceflight's impact on biological systems, ensuring humans will thrive in future deep space missions.

OSDR↗
DOE OSTI2019

Corrosion Behavior of Fe-7Cr-1Mo-12Zr Metal Waste Form Alloy in Simulated Repository Environment

Metal waste forms (MWF) are solid metallic waste categorized as high-level radioactive waste generated during pyro-reprocessing of spent metallic fuels and geologically disposed off. This waste form generated requires an excellent corrosion resistance in a geological repository environment. In the present work, Fe-7Cr-1Mo-12Zr MWF alloy was developed by casting in an arc melting furnace. The x-ray diffraction analysis revealed the formation of stable phases of α-Fe solid solution and the intermetallic phases of Fe{sub 2}Zr and Fe{sub 23}Zr{sub 6}. The corrosion behavior of Fe-7Cr-1Mo-12Zr alloy was investigated using electrochemical techniques in aggressive (highly acidic with Cl{sup −}) and nominal repository pH environment. Cyclic potentiodynamic polarization studies indicated the shift in corrosion potential toward cathodic potential in highly acidic solution with Cl{sup −}. The corrosion mechanism of pitting is associated with acidified pH medium with more Cl{sup −}, whereas uniform corrosion or transpassive dissolution is resultant of mild acidity or mild alkaline medium. The passive region is wider in pH 5 and 8 when compared to pH 1 and 3. Electrochemical impedance spectroscopic (EIS) analysis revealed the lowering of passive film stability in the highly acidic medium in the presence of Cl{sup −}. The role of passive oxide layers on the corrosion resistance of the Fe-7Cr-1Mo-12Zr MWF alloy is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Chemical degradation of fly ash blended concrete with the seasonal variation of rainwater in a radioactive waste repository: A thermodynamic modeling approach

Highlights: • The thermodynamic model for the cementitious system was successfully developed. • The chemical degradation of concrete was greatly affected by rainwater types. • Inorganic carbon species in rainwater reduced the chemical resistance of concrete. • The durability of concrete to rainwater decreased with increasing fly ash content. This study presents a long-term degradation behavior of fly ash blended concrete in a vault type low- and intermediate-level radioactive waste (LILW) repository by thermodynamic equilibrium calculations using PHREEQC combined with CEMDATA18 database. Since rainwater plays a predominant role as leachate for the concrete waste container in the repository, the effect of chemical properties of seasonal rainwater on the chemical degradation of concrete was analyzed. In addition, the impact of the blending with fly ash on the chemical degradation was evaluated through a gradual replacement of ordinary Portland cement (OPC) by fly ash. Regardless of the replacement level, autumn rainwater showed the greatest influence on the concrete degradation owing to the presence of inorganic carbon species, which induce the carbonation. The resistance of concrete to chemical degradation by rainwater was persistently reduced due to the decreasing formation of portlandite and calcium silicate hydrate (C-S-H) with increasing replacement level.

36 MATERIALS SCIENCE↗
DOE OSTI2015

On the impact of temperatures up to 200°C in clay repositories with bentonite engineer barrier systems: A study with coupled thermal, hydrological, chemical, and mechanical modeling

One of the most important design variables for a geological nuclear waste repository is the temperature limit up to which the engineered barrier system (EBS) and the natural geologic environment can be exposed. Up to now, almost all design concepts that involve bentonite-backfilled emplacement tunnels have chosen a maximum allowable temperature of about 100°C. Such a choice is largely based on the consideration that in clay-based materials illitization and the associated mechanical changes in the bentonite (and perhaps the clay host rock) could affect the barrier attributes of the EBS. However, existing experimental and modeling studies on the occurrence of illitization and related performance impacts are not conclusive, in part because the relevant couplings between the thermal, hydrological, chemical, and mechanical (THMC) processes have not been fully represented in the models. This work presents a fully coupled THMC simulation of a nuclear waste repository in a clay formation with a bentonite-backfilled EBS for 1000 years. Two scenarios were simulated for comparison: a case in which the temperature in the bentonite near the waste canister can reach about 200°C and a case in which the temperature in the bentonite near the waste canister peaks at about 100°C. The model simulations demonstrate some degree of illitization in both the bentonite buffer and the surrounding clay formation. Other chemical alterations include the dissolution of K-feldspar and calcite, and precipitation of quartz, chlorite, and kaolinite. In general, illitization in the bentonite and the clay formation is enhanced at higher temperature. However, the quantity of illitization is affected by many chemical factors and therefore varies a great deal. The most important chemical factors are the concentration of K in the pore water as well as the abundance and dissolution rate of K-feldspar; less important ones are the concentration of sodium and the quartz precipitation rate. In our modeling scenarios, the calculated decrease in smectite volume fraction in bentonite ranges from 1 to 8% of the initial volume fraction of smectite in the 100°C scenario and 1–27% in the 200°C scenario. Chemical changes in the 200°C scenario could also lead to a reduction in swelling stress up to 15–18% whereas those in the 100°C scenario result in about 14–15% reduction in swelling stress for the base case scenario. Model results also show that the 200°C scenario results in a much higher total stress than the 100°C scenario, mostly due to thermal pressurization. While cautions should be taken regarding the model results due to some limitations in the models, the modeling work is illustrative in light of the relative importance of different processes occurring in EBS bentonite and clay formation at higher than 100°C conditions, and could be of greater use when site specific data are available.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

A comparative study of discrete fracture network and equivalent continuum models for simulating flow and transport in the far field of a hypothetical nuclear waste repository in crystalline host rock

One of the major challenges of simulating flow and transport in the far field of a geologic repository in crystalline host rock is related to reproducing the properties of the fracture network over the large volume of rock with sparse fracture characterization data. Various approaches have been developed to simulate flow and transport through the fractured rock. The approaches can be broadly divided into Discrete Fracture Network (DFN) and Equivalent Continuum Model (ECM). The DFN explicitly represents individual fractures, while the ECM uses fracture properties to determine equivalent continuum parameters. In this paper, we compare DFN and ECM in terms of upscaled observed transport properties through generic fracture networks. The major effort was directed on making the DFN and ECM approaches similar in their conceptual representations. This allows for separating differences related to the interpretation of the test conditions and parameters from the differences between the DFN and ECM approaches. The two models are compared using a benchmark test problem that is constructed to represent the far field (1 × 1 × 1 km 3 ) of a hypothetical repository in fractured crystalline rock. The test problem setting uses generic fracture properties that can be expected in crystalline rocks. The models are compared in terms of the: 1) effective permeability of the domain, and 2) nonreactive solute breakthrough curves through the domain. The principal differences between the models are mesh size, network connectivity, matrix diffusion and anisotropy. We demonstrate how these differences affect the flow and transport. Finally, we identify the factors that should be taken in consideration when selecting an approach most suitable for the site-specific conditions.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

StaNdaRT: a repository of standardised test models and outputs for supernova radiative transfer

We present the first results of a comprehensive supernova (SN) radiative-transfer (RT) code-comparison initiative (StaNdaRT), where the emission from the same set of standardised test models is simulated by currently used RT codes. We ran a total of ten codes on a set of four benchmark ejecta models of Type Ia SNe. We consider two sub-Chandrasekhar-mass (M tot = 1.0 M ⊙ ) toy models with analytic density and composition profiles and two Chandrasekhar-mass delayed-detonation models that are outcomes of hydrodynamical simulations. We adopt spherical symmetry for all four models. The results of the different codes, including the light curves, spectra, and the evolution of several physical properties as a function of radius and time are provided in electronic form in a standard format via a public repository. We also include the detailed test model profiles and several Python scripts for accessing and presenting the input and output files. We also provide the code used to generate the toy models studied here. In this paper, we describe the test models, radiative-transfer codes, and output formats in detail, and provide access to the repository. We present example results of several key diagnostic features.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

The Geant4 physics validation repository

The Geant4 collaboration regularly performs validation and regression tests. The results are stored in a central repository and can be easily accessed via a web application. In this article we describe the Geant4 physics validation repository which consists of a relational database storing experimental data and Geant4 test results, a java API and a web application. Lastly, the functionality of these components and the technology choices we made are also described

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2017

Software aspects of the Geant4 validation repository

The Geant4, GeantV and GENIE collaborations regularly perform validation and regression tests for simulation results. DoSSiER (Database of Scientic Simulation and Experimental Results) is being developed as a central repository to store the simulation results as well as the experimental data used for validation. DoSSiER is easily accessible via a web application. In addition, a web service allows for programmatic access to the repository to extract records in JSON or XML exchange formats. In this article, we describe the functionality and the current status of various components of DoSSiER as well as the technology choices we made.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

An Open-Access Repository of Synchrophasor Data Quality Examples: Curation and Example Applications

Synchrophasor measurements are critical in providing wide-area situational awareness to power system operators. However, data artifacts may be introduced due to various issues such as loss of communication, loss of GPS signal, internal clock error, and vendor-specific implementation of phasor estimation algorithms. Tools designed to provide actionable insights from synchrophasor data, hence, must be designed to be robust to these data quality issues. In this work, two years of synchrophasor data sourced from multiple electric utilities in the United States were analyzed to identify examples of data quality problems. These examples were then labeled and published in the Grid Event Signature Library, a publicly available repository of power system measurements hosted by the Oak Ridge National Laboratory. This paper describes the data curation process, and illustrates two application use cases where the dataset can be valuable to the research community. In the first use case, a random forest classifier is trained to distinguish power system disturbance signatures from data anomalies introduced in synchrophasor measurements due to clock errors. The second use case studies the impact of data quality issues on an example synchrophasor application (specifically, event start time determination). The choice of data quality problems investigated is informed by the examples in the repository curated in this work.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2013

Modelling study to evaluate two variants for accessing a deep geological repository from the point of view of long-term safety

Siting a deep geological repository for radioactive waste essentially involves two interrelated steps: deciding on an appropriate geological environment for the underground facilities and selecting a suitable location for the associated surface facility. An acceptable solution is more easily achieved if some flexibility exists for siting the surface facility, irrespective of the exact position of the underground facilities. Such flexibility is available if a ramp is used as the main access route from the surface facility to the underground facilities. Another option is to use a combination of shafts and (sub)horizontal tunnels as the main access route. Both variants include shafts for ventilation, etc. In this paper, the two variants (i) main access via ramp and (ii) main access via shaft are compared in terms of long-term safety. To this end, the entire network of underground tunnels of a deep geological repository is implemented in an analytical resistor network flow model. Radionuclide release through the tunnel system and the host rock is then calculated with a numerical network transport model, using as input the results from the flow model. The results clearly indicate that, even in case of hypothetically deficient horizontal and sub-horizontal sealing elements, the choice between ramp and shaft as the main access route is irrelevant to long-term safety. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Public involvement on closure of Asse II radioactive waste repository in Germany

From 1967 to 1978, about 125,800 barrels of low- and intermediate level waste were disposed of - nominally for research purposes - in the former 'Asse' salt mine which had before been used for the production of potash for many years. Since 1988 an inflow of brine is being observed which will cause dangers of flooding and of a collapse due to salt weakening and dissolution if it should increase. Since several years the closure of the Asse repository is planned with the objective to prevent the flooding and collapse of the mine and the release of radioactive substances to the biosphere. The first concept that was presented by the former operator, however, seemed completely unacceptable to regional representatives from politics and NGOs. Their activities against these plans made the project a top issue on the political agenda from the federal to the local level. The paper traces the main reasons which lead to the severe safety problems in the past as well as relevant changes in the governance system today. A focus is put on the process for public involvement in which the Citizens' Advisory Group 'A2B' forms the core measure. Its structure and framework, experience and results, expectations from inside and outside perspectives are presented. Furthermore the question is tackled how far this process can serve as an example for a participatory approach in a siting process for a geological repository for high active waste which can be expected to be highly contested in the affected regions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Development of a specific methodology to assess suitable sites to receive a repository for L/ILW waste in the Portuguese territory

Portugal does not have nuclear power plants but records an increasing production of radioactive waste from medical, industrial and research applications of radioactive materials in the form of sealed and unsealed sources; the country totals include also the spent fuel of one nuclear reactor for research purposes. Since radioactive waste management policies and practices in Portugal will have to comply with the Council Directive 2011/70/Euratom and the IAEA Joint Convention, the search for scientific and technological solutions to deal with radioactive wastes produced in the country started some years ago. The research carried out recently under the scope of a national funded project (KADRWaste, PTDC/CTEGEX/ 82678/2006) represents a firm step in this commitment. Indeed, the transfer of methodologies tested and validated in this project allowed for improvement to a procedure to assess suitable sites to receive a near-surface repository for 'Low and Intermediate Level Waste, Short Live and Long Live' (LILWSL, LL) wastes in Portugal mainland. Although the main stages of the procedure can be of universal usage, details were designed according to the intrinsic geological, geomorphic and meteorological features of previously selected target-areas. All the requirements exhaustively listed in many reports of the IAEA were fulfilled and, in addition, the application of mineralogical, geochemical and textural criteria is strongly advised. The proposed procedure is based on a 5 key-steps approach preceded by clarification of the boundary conditions to be imposed, which are crucial to the inventory of various compulsory technical requirements. This analysis requires the adoption of stringent criteria, many of them of multidisciplinary nature, including tests of vulnerability and assessment of uncertainty, besides the environmental impact risk. As a result, priority targets that are not excluded will integrate different classes and, depending on the existing knowledge, it will be possible to select locations suitable for the repository installation, taking into account also the political, social and administrative dimensions behind this decision. (authors)

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