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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Do We Need Daily Image-Guided Radiotherapy by Megavoltage Computed Tomography in Head and Neck Helical Tomotherapy? The Actual Delivered Dose to the Spinal Cord

Purpose: To quantify the actual delivered dose to the cervical spinal cord with different image-guided radiotherapy (IGRT) approaches during head and neck (HN) cancer helical tomotherapy. Methods and Materials: Twenty HN patients (HNpts) treated with bilateral nodal irradiation were analyzed. Daily megavoltage computed tomography MVCT) scans were performed for setup purposes. The maximum dose on the planning CT scan (plan-Dmax) and the magnitude and localization of the actual delivered Dmax (a-Dmax) were analyzed for four scenarios: daily image-guided radiotherapy (dIGRT), twice weekly IGRT (2 Multiplication-Sign WkIGRT), once weekly IGRT (1 Multiplication-Sign WkIGRT), and no IGRT at all (non-IGRT). The spinal cord was recontoured on 236 MVCTs for each scenario (total, 944 fractions), and the delivered dose was recalculated for each fraction (fx) separately. Results: Fifty-one percent of the analyzed fx for dIGRT, 56% of the analyzed fx for the 2 Multiplication-Sign WkIGRT, 62% of the analyzed fx for the 1 Multiplication-Sign WkIGRT, and 63% of the analyzed fx for the non-IGRT scenarios received a higher a-Dmax than the plan-Dmax. The median increase of dose in these fx was 3.3% more for dIGRT, 5.8% more for 2 Multiplication-Sign WkIGRT, 10.0% more for 1 Multiplication-Sign WkIGRT, and 9.5% more for non-IGRT than the plan-Dmax. The median spinal cord volumes receiving a higher dose than the plan-Dmax were 0.02 cm{sup 3} for dIGRT, 0.11 cm{sup 3} for 2 Multiplication-Sign WkIGRT, 0.31 cm{sup 3} for 1 Multiplication-Sign WkIGRT, and 0.22 cm{sup 3} for non-IGRT. Differences between the dIGRT and all other scenarios were statistically significant (p < 0.05). Conclusions: Compared to the Dmax of the initial plan, daily IGRT had the smallest increase in dose. Furthermore, daily IGRT had the lowest proportion of fractions and the smallest volumes affected by a dose that was higher than the planned dose. For patients treated with doses close to the tolerance dose of the spinal cord, we recommend daily IGRT. For all other cases, twice weekly IGRT is sufficient.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Development and assessment of a reactor system prognosis model with physics-guided machine learning

Autonomous control systems provide recommendations to help operators in decision-making during plant operations ranging from normal operation to accident management. An important step of autonomous control is prognosis. In nuclear engineering domain, prognosis is the process of predicting future conditions of a system or equipment based on present signs and symptoms of a fault. The prognosis model allows predicting future reactor states for possible candidate control strategies so that the outcomes can be evaluated to determine the best control strategy. The prognosis model requires representing direct relationships between the symptoms and the predictions. In nuclear engineering, computational simulations are approximate representations of the operation of the real system. However, prognosis with computational simulations requires high computation power and time due to possible large number of scenarios. Necessary computation resources can be reduced with machine learning (ML) approach for fast predictions by building a surrogate function using the simulation data. A critical issue is, ML models are ignorant of physical knowledge, and these models approximate statistical relationships between the system variables. This ignorance can produce results that are inconsistent with physical laws, even if an optimal result is achieved from a mathematical point of view. Physics-guided machine learning (PGML) is an approach to tackle this issue. Here, this work formulates and illustrates a framework to guide development and assessment of the ML-based prognosis model for autonomous control systems. The development of the prognosis model considers the training of a ML model which consists of optimizing many aspects of the ML approach. The assessment of the prognosis model considers training data limitations and uncertainties of the ML approach. Prognosis models with standalone ML and PGML are developed and assessed on the loss-of-flow scenario of Experimental Breeder Reactor II. The results indicate that PGML based prognosis model has the best performance compared to other prognosis models.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2021

The effect of a transducer’s spatial averaging on an elastodynamic guided wave’s wavenumber spectrum

Elastodynamic guided waves propagate in an elastic solid which makes it difficult, if not impractical, to place a receiving transducer in the direct path of the propagating wave (as one would for an acoustic wave in a fluid medium). Thus, to account for this, receiving transducers are often placed on the surface of the solid waveguide such that the transducer surface is parallel to the wave propagation direction. This transducer orientation introduces spatial averaging, which causes the received signal to have an altered signal amplitude and mode bias. We investigate both of these effects and present a simple model from which we derive a scaling-ratio expression that describes the effects of spatial averaging. Furthermore, we then test its performance using finite-element simulations that incorporate “real-world” assumptions (e.g., transient waves, piezoelectric effects, etc.). The results from the simulations demonstrate that the scaling-ratio can characterize the effects resulting from spatial averaging. The scaling-ratio expression will be particularly useful when designing experiments involving high frequency (small wavelength) guided waves. Lastly, the proposed scaling-ratio expression could be applied to other sensing methods, like Laser Doppler Vibrometry (LDV) or piezoelectric waveguides with inter-digitated transducers, because of its generality. However, the authors are careful to note that the scaling-ratio expression is not intended as a replacement of multi-physics analysis or good experimental design, and the effects of spatial averaging should be avoided whenever possible.

2DFFT↗
DOE OSTI2018

Energy Conversion by Parallel Electric Fields During Guide Field Reconnection in Scaled Laboratory and Space Experiments

Here, we present direct and scaled comparisons between laboratory and in situ space observations of magnetic reconnection with a guide field, comparing results from the Magnetospheric Multiscale Mission and the Magnetic Reconnection eXperiment (MRX). While Magnetospheric Multiscale Mission observations obtain high–resolution and fully kinetic data, MRX observations fully cover the 2–D reconnection plane near the current sheet, removing uncertainties in situating the measurements compared to the reconnection region. Through scaling transformations, we show a quantitative agreement in magnetic field and current density profiles, which agree within a factor of 2 from each other. The introduction of the guide field causes the energy conversion J·E in the current sheet to be dominated by J || E || in both cases. However, parallel electric fields reported by recent spacecraft crossings are significantly (5–10 times) larger than values obtained on MRX, highlighting an important issue for understanding energy conversion by reconnection.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2015

Compact turnkey focussing neutron guide system for inelastic scattering investigations

We demonstrate the performance of a compact neutron guide module which boosts the intensity in inelastic neutron scattering experiments by approximately a factor of 40. The module consists of two housings containing truly curved elliptic focussing guide elements, positioned before and after the sample. The advantage of the module lies in the ease with which it may be reproducibly mounted on a spectrometer within a few hours, on the same timescale as conventional sample environments. It is particularly well suited for samples with a volume of a few mm{sup 3}, thus enabling the investigation of materials which to date would have been considered prohibitively small or samples exposed to extreme environments, where there are space constraints. We benchmark the excellent performance of the module by measurements of the structural and magnetic excitations in single crystals of model systems. In particular, we report the phonon dispersion in the simple element lead. We also determine the magnon dispersion in the spinel ZnCr{sub 2}Se{sub 4} (V = 12.5 mm{sup 3}), where strong magnetic diffuse scattering at low temperatures evolves into distinct helical order.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

A Redundancy-Guided Approach for the Hazard Analysis of Digital Instrumentation and Control Systems in Advanced Nuclear Power Plants

We report digital instrumentation and control (I&C) upgrades are a vital research area for the nuclear industry. Despite their performance benefits, deployment of digital I&C in nuclear power plants (NPPs) has been limited. Digital I&C systems exhibit complex failure modes including common cause failures (CCFs), which can be difficult to identify. This paper describes the development of a redundancy-guided application of the Systems-Theoretic Process Analysis and fault tree analysis for the hazard analysis of digital I&C in advanced NPPs. The resulting Redundancy-Guided Systems-Theoretic Hazard Analysis (RESHA) is applied for the case study of a representative state-of-the-art digital reactor trip system. The analysis qualitatively and systematically identifies the most critical CCFs and other hazards of digital I&C systems. Ultimately, the RESHA can help researchers make informed decisions for how, and to what degree, defensive measures such as redundancy, diversity, and defense in depth can be used to mitigate or eliminate the potential hazards of digital I&C systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2012

Systematic measurements of whole-body imaging dose distributions in image-guided radiation therapy

Purpose: The full benefit of the increased precision of contemporary treatment techniques can only be exploited if the accuracy of the patient positioning is guaranteed. Therefore, more and more imaging modalities are used in the process of the patient setup in clinical routine of radiation therapy. The improved accuracy in patient positioning, however, results in additional dose contributions to the integral patient dose. To quantify this, absorbed dose measurements from typical imaging procedures involved in an image-guided radiation therapy treatment were measured in an anthropomorphic phantom for a complete course of treatment. The experimental setup, including the measurement positions in the phantom, was exactly the same as in a preceding study of radiotherapy stray dose measurements. This allows a direct combination of imaging dose distributions with the therapy dose distribution. Methods: Individually calibrated thermoluminescent dosimeters were used to measure absorbed dose in an anthropomorphic phantom at 184 locations. The dose distributions from imaging devices used with treatment machines from the manufacturers Accuray, Elekta, Siemens, and Varian and from computed tomography scanners from GE Healthcare were determined and the resulting effective dose was calculated. The list of investigated imaging techniques consisted of cone beam computed tomography (kilo- and megavoltage), megavoltage fan beam computed tomography, kilo- and megavoltage planar imaging, planning computed tomography with and without gating methods and planar scout views. Results: A conventional 3D planning CT resulted in an effective dose additional to the treatment stray dose of less than 1 mSv outside of the treated volume, whereas a 4D planning CT resulted in a 10 times larger dose. For a daily setup of the patient with two planar kilovoltage images or with a fan beam CT at the TomoTherapy unit, an additional effective dose outside of the treated volume of less than 0.4 mSv and 1.4 mSv was measured, respectively. Using kilovoltage or megavoltage radiation to obtain cone beam computed tomography scans led to an additional dose of 8-46 mSv. For treatment verification images performed once per week using double exposure technique, an additional effective dose of up to 18 mSv was measured. Conclusions: Daily setup imaging using kilovoltage planar images or TomoTherapy megavoltage fan beam CT imaging can be used as a standard procedure in clinical routine. Daily kilovoltage and megavoltage cone beam computed tomography setup imaging should be applied on an individual or indication based protocol. Depending on the imaging scheme applied, image-guided radiation therapy can be administered without increasing the dose outside of the treated volume compared to therapies without image guidance.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-527: Prior Knowledge Guided TomoTherapy Treatment Planning

Purpose: The quality and efficiency of radiotherapy treatment planning are highly planer dependent. Previously we have developed a statistical model to correlate anatomical features with dosimetry features of head and neck Tomotherapy treatment. The model enables us to predict the best achievable dosimetry for individual patient prior to treatment planning. The purpose of this work is to study if the prediction model can facilitate the treatment planning in both the efficiency and dosimetric quality. Methods: The anatomy-dosimetry correlation model was used to calculate the expected DVH for nine patients formerly treated. In Group A (3 patients), the model prediction agreed with the clinic plan; in Group B (3 patients), the model predicted lower larynx mean dose than the clinic plan; in Group C (3 patients), the model suggested the brainstem could be further spared. Guided by the prior knowledge, we re-planned all 9 cases. The number of interactions during the optimization process and dosimetric endpoints between the original clinical plan and model-guided re-plan were compared. Results: For Group A, the difference of target coverage and organs-at-risk sparing is insignificant (p>0.05) between the replan and the clinical plan. For Group B, the clinical plan larynx median dose is 49.4±4.7 Gy, while the prediction suggesting 40.0±6.2 Gy (p<0.05). The re-plan achieved 41.5±6.6 Gy, with similar dose on other structures as clinical plan. For Group C, the clinical plan brainstem maximum dose is 44.7±5.5 Gy. The model predicted lower value 32.2±3.8 Gy (p<0.05). The re-plans reduced brainstem maximum dose to 31.8±4.1 Gy without affecting the dosimetry of other structures. In the replanning of the 9 cases, the times operator interacted with TPS are reduced on average about 50% compared to the clinical plan. Conclusion: We have demonstrated that the prior expert knowledge embedded model improved the efficiency and quality of Tomotherapy treatment planning.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

Solar Powering Your Community: A Guide for Local Governments, Second Edition (Fact Sheet)

This fact sheet describes the details of the Solar Powering Your Community: A Guide for Local Governments. This report has been developed by the U.S. Department of Energy (DOE) as a comprehensive resource to assist local governments and stakeholders in designing and implementing a strategic local solar plan. The guide presents helpful information on a wide array of topics that are of particularinterest to cities and local communities.

14 SOLAR ENERGY↗
DOE OSTI2013

Advanced Energy Retrofit Guide: Practical Ways to Improve Energy Performance; Grocery Stores (Revised) [Book]

The U.S. Department of Energy developed the Advanced Energy Retrofit Guides (AERGs) to provide specific methodologies, information, and guidance to help energy managers and other stakeholders successfully plan and execute energy efficiency improvements. Detailed technical discussion is fairly limited in these guides. Instead, we emphasize actionable information, practical methodologies, diversecase studies, and unbiased evaluations of the most promising retrofit measures for each building type. A series of AERGs is under development, addressing key segments of the commercial building stock. Grocery stores were selected as one of the highest priority sectors, because they represent one of the most energy-intensive market segments.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Advanced Energy Retrofit Guide: Practical Ways to Improve Energy Performance, K-12 Schools (Book)

The U.S. Department of Energy developed the Advanced Energy Retrofit Guides (AERGs) to provide specific methodologies, information, and guidance to help energy managers and other stakeholders plan and execute energy efficiency improvements. Detailed technical discussion is fairly limited. Instead, we emphasize actionable information, practical methodologies, diverse case studies, and unbiased evaluations of the most promising retrofit energy efficiency measures for each building type. A series of AERGs is under development, addressing key segments of the commercial building stock. K-12 schools were selected as one of the highest priority building sectors, because schools affect the lives of most Americans. They also represent approximately 8% of the energy use and 10% of the floor area in commercial buildings nationwide. U.S. K-12 school districts spend more than $8 billion each year on energy - more than they spend on computers and textbooks combined. Most occupy older buildings that often have poor operational performance - more than 30% of schools were built before 1960. The average age of a school is about 42 years - which is nearly the expected serviceable lifespan of the building. K-12 schools offer unique opportunities for deep, cost-effective energy efficiency improvements, and this guide provides convenient and practical guidance for exploiting these opportunities in the context of public, private, and parochial schools.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

RELAP-7 User's Guide

The document contains a user's guide on how to run the RELAP-7 code. The RELAP-7 code is the next generation nuclear reactor system safety analysis code being developed at the Idaho National Laboratory. RELAP-7 will become the main reactor systems simulation toolkit for the LWRS (Light Water Reactor Sustainability) program’s RISMC (Risk Informed Safety Margin Characterization) effort and the next generation tool in the RELAP reactor safety/systems analysis application series. RELAP-7 is written with object oriented programming language C++. A number of example problems and their associated input files are presented in this document to guide users to run the RELAP-7 code starting with simple pipe problems to problems with increasing complexity.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

Quality Assurance Framework Implementation Guide for Isolated Community Power Systems

This implementation guide is a companion document to the 'Quality Assurance Framework for Mini-Grids' technical report. This document is intended to be used by one of the many stakeholder groups that take part in the implementation of isolated power systems. Although the QAF could be applied to a single system, it was designed primarily to be used within the context of a larger national or regional rural electrification program in which many individual systems are being installed. This guide includes a detailed overview of the Quality Assurance Framework and provides guidance focused on the implementation of the Framework from the perspective of the different stakeholders that are commonly involved in expanding energy development within specific communities or regions. For the successful long-term implementation of a specific rural electrification program using mini-grid systems, six key stakeholders have been identified that are typically engaged, each with a different set of priorities 1. Regulatory agency 2. Governmental ministry 3. System developers 4. Mini-utility 5. Investors 6. Customers/consumers. This document is broken into two distinct sections. The first focuses on the administrative processes in the development and operation of community-based mini-grid programs, while the second focuses on the process around the installation of the mini-grid project itself.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2017

Construction Guide to Next-Generation High-Performance Walls in Climate Zones 3-5 - Part 2: 2x4 Walls

Part 2 of this Construction Guide to High-Performance Walls in Climate Zones 3-5 provides straightforward and cost-effective strategies to construct durable, energy-efficient walls. It addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 inches thick over the WSP, and a cladding system installed over the foam sheathing in low-rise residential buildings up to three stories high. Walls with 2x6 framing are addressed in Part 1 of the Guide.

2x4 wood frame studs↗
DOE OSTI2017

Construction Guide to Next-Generation High-Performance Walls in Climate Zones 3-5 - Part 2: 2x4 Walls

Part 2 of this Construction Guide to High-Performance Walls in Climate Zones 3-5 provides straightforward and cost-effective strategies to construct durable, energy-efficient walls. It addresses walls constructed with 2x4 wood frame studs, wood structural panel (WSP) sheathing as wall bracing and added backing for foam sheathing, a layer of rigid foam sheathing insulation up to 1.5 inches thick over the WSP, and a cladding system installed over the foam sheathing in low-rise residential buildings up to three stories high. Walls with 2x6 framing are addressed in Part 1 of the Guide.

2x4 wood frame studs↗
DOE OSTI2019

SAM User's Guide

The System Analysis Module (SAM) is a modern system analysis tool being developed at Argonne National Laboratory for advanced non-LWR safety analysis. It aims to provide fast-running, whole-plant transient analyses capability with improved-fidelity for Sodium-cooled Fast Reactors (SFR), Lead-cooled Fast Reactors (LFR), and Molten Salt Reactors (MSR) or Fluoride-cooled High-temperature Reactors (FHR). SAM takes advantage of advances in physical modeling, numerical methods, and software engineering to enhance its user experience and usability. It utilizes an object-oriented application framework (MOOSE), and its underlying meshing and finite-element library (libMesh) and linear and non-linear solvers (PETSc), to leverage the modern advanced software environments and numerical methods. This document provides a user’s guide, which will help users understand the input description and core capabilities of the SAM code. A brief overview of the code is presented, as well as how to obtain and run it. The input syntax for various parts of the code is provided. Additionally, a number of example problems, starting with simple unit component problems to problems with increasing complexity, are provided. Because the code is still under active development, this SAM User’s Guide will evolve with periodic updates.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2021

SAM User’s Guide

The System Analysis Module (SAM) is a modern system analysis tool being developed at Argonne National Laboratory for advanced non-LWR safety analysis. It aims to provide fast-running, whole-plant transient analyses capability with improved-fidelity for Sodium-cooled Fast Reactors (SFR), Lead-cooled Fast Reactors (LFR), and Molten Salt Reactors (MSR) or Fluoride-cooled High-temperature Reactors (FHR). SAM takes advantage of advances in physical modeling, numerical methods, and software engineering to enhance its user experience and usability. It utilizes an object-oriented application framework (MOOSE), and its underlying meshing and finite-element library (libMesh) and linear and non-linear solvers (PETSc), to leverage the modern advanced software environments and numerical methods. This document provides a user’s guide, which will help users understand the input description and core capabilities of the SAM code. A brief overview of the code is presented, as well as how to obtain and run it. The input syntax for various parts of the code is provided. Additionally, a number of example problems, starting with simple unit component problems to problems with increasing complexity, are provided. Because the code is still under active development, this SAM User’s Guide will evolve with periodic updates.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2022

Light Weight Radioisotope Heater Unit User’s Guide

This user's guide provides an overview of Light Weight Radioisotope Heater Units (LWRHU), including aspects of its physical design and performance under normal operations. This guide also identifies the planning and execution involved in launching a nuclear payload. Physical characteristics, interfaces, and environmental characteristics of the LWRHU are discussed in detail. Information relating to project management interfaces and effort.

07 ISOTOPE AND RADIATION SOURCES↗