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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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29 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

FFTF Passive Safety Test Data for Benchmarks for New LMR Designs

Liquid Metal Reactors (LMRs) continue to be considered as an attractive concept for advanced reactor design. Software packages such as SASSYS are being used to im-prove new LMR designs and operating characteristics. Significant cost and safety im-provements can be realized in advanced liquid metal reactor designs by emphasizing inherent or passive safety through crediting the beneficial reactivity feedbacks associ-ated with core and structural movement. This passive safety approach was adopted for the Fast Flux Test Facility (FFTF), and an experimental program was conducted to characterize the structural reactivity feedback. The FFTF passive safety testing pro-gram was developed to examine how specific design elements influenced dynamic re-activity feedback in response to a reactivity input and to demonstrate the scalability of reactivity feedback results to reactors of current interest. The U.S. Department of En-ergy, Office of Nuclear Energy Advanced Reactor Technology program is in the pro-cess of preserving, protecting, securing, and placing in electronic format information and data from the FFTF, including the core configurations and data collected during the passive safety tests. Benchmarks based on empirical data gathered during operation of the Fast Flux Test Facility (FFTF) as well as design documents and post-irradiation examination will aid in the validation of these software packages and the models and calculations they produce. Evaluation of these actual test data could provide insight to improve analytical methods which may be used to support future licensing applications for LMRs

Wootan, David W.↗
DOE OSTI2017

High-Field Nb3Sn Cos-theta Dipole with Stress Management

Cost-effective superconducting dipole magnets with operating fields up to 16 T are being considered for the LHC en-ergy upgrade (HE-LHC) and a Future Circular Collider (FCC). To demonstrate feasibility of 15 T accelerator quality dipole mag-nets, FNAL as a part of the US-MDP is developing a single-aper-ture Nb3Sn dipole demonstrator based on a 4-layer graded cos-theta coil with 60 mm aperture and cold iron yoke. In parallel, to explore the limit of the Nb3Sn accelerator magnet technology, op-timize magnet design and performance parameters, and reduce magnet cost, magnet design studies are also being performed to push the nominal bore field to 16 T in a 60-mm aperture cos-theta dipole. Results of these studies are reported and discussed in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Dielectric-plate-implanted Higher Order Mode (HOM) Waveguide for High Intensity Multi-beam Device Application

A mode-selective oversized RF-beam channel has been investigated for high intensity multi-beam devices. Implanting the equi-spaced dielectric plates at the transverse positions where longitudinal electric fields of a HOM are minimal in the mic ro-metallic structure strongly suppresses all lower energy modes and other wakefield modes. The dielectric lattice captures only a single HOM of the wavelengths that correspond to the plate spacing. Electromagnetic simulations have shown that the lower en ergy modes, TE10 and TE20 modes, are suppressed down to < ~ -60 dB by two plate loads, while TE310-mode prominently propagates through the 2 mm long waveguide only with 4 dB (= -2dB/mm) at 1 THz. The numerical calculation indicated that the TE30 mode has ~ a few times higher Q than the lower energy modes. The strong single mode selectivity has been extensively looked into with a more highly overmoded structure. Feasibility analysis of the HOM structure for multi-beam device application is under investiga tion. Particle-in-cell (PIC) simulation has shown coherent beam bunching and energy gain from THz driving signal.

43 PARTICLE ACCELERATORS↗
DOE OSTI2023

Scalable Graph Analytics and HPC Operational Enhancement: Parallel Computing and ML/DL Innovations

Parallel computing plays a pivotal role in the efficient processing of large-scale graphs. Complex network analysis stands as a capti- vating research frontier, holding promise across diverse scientific domains such as sociology, biology, online media, and recommenda- tion systems. In this era, Machine Learning (ML) and Deep Learning (DL) have emerged as indispensable tools, underpinning remarkable technological achievements. Within this dynamic landscape, my research revolves around advancing parallel algorithms tailored for large-scale graph operations. To achieve this, I harness the power of cutting-edge technologies including OpenMP, MPI, HIP, and CUDA, on the High-Performance Computing (HPC) platforms to unlock optimal performance. I also apply ML/DL techniques to HPC operational data, to streamline the monitoring and maintenance of supercomputers, alleviating the complexities associated with their upkeep and enhancing user support. My research echoes the syn- ergy between parallel computing, large-scale graph analysis, and ML/DL, improving computational efficiency and user experience.

Sattar, Naw Safrin↗
DOE OSTI2019

An investigation of a novel reusable radiochromic sheet for 2D dose measurement

Purpose Radiochromic film remains a useful and versatile clinical dosimetry tool. Current film options are single use. Here, we introduce a novel prototype two‐dimensional (2D) radiochromic sheet, which optically clears naturally at room temperature after irradiation and can be reused. We evaluate the sheets for potential as a 2D dosimeter and as a radiochromic bolus with capability for dose measurement. Methods A novel derivative of reusable Presage ® was manufactured into thin sheets of 5 mm thickness. The sheets contained 2% cumin‐leucomalachitegreen‐diethylamine (LMG‐DEA) and plasticizer (up to 25% by weight). Irradiation experiments were performed to characterize the response to megavoltage radiation, including dose sensitivity, temporal decay rate, consistency of repeat irradiations, intra and inter‐sheet reproducibility, multi‐modality response (electrons and photons), and temperature sensitivity (22°C to 36°C). The local change in optical‐density (ΔOD), before and after radiation, was obtained with a flat‐bed film scanner and extracting the red channel. Repeat scanning enabled investigation of the temporal decay of ΔOD. Additional studies investigated clinical utility of the sheets through application to IMRT treatment plans (prostate and a TG119 commissioning plan), and a chest wall electron boost treatment. In the latter test, the sheet performed as a radiochromic bolus. Results The radiation induced OD change in the sheets was found to be proportional to dose and to exponentially decay to baseline in ~24 h (R2 = 0.9986). The sheet could be reused and had similar sensitivity (within 1% after the first irradiation) for at least eight irradiations. Importantly, no memory of previous irradiations was observed within measurement uncertainty. The consistency of dose response from photons (6 and 15 MV) and electrons (6–20 MeV) was found to be within calibration uncertainty (~1%). The dose sensitivity of the sheets had a temperature dependence of 0.0012 ΔOD/°C. For the short (1 min) single field IMRT QA verification, good agreement was observed between the Presage sheet and EBT film (gamma pass rate 97% at 3% 3 mm dose‐difference and distance‐to‐agreement tolerance, with a 10% threshold). For the longer (~13 min) TG‐119 9‐field IMRT verification the gamma agreement was lower at 93% pass rate at 5% 3 mm, 10% threshold, when compared with Eclipse. The lower rate is attributed to uncertainty arising from signal decay during irradiation and indicates a current limitation. For the electron cutout treatment, both Presage and EBT agreed well (within 2% RMS difference) but differed from the Eclipse treatment plan (~7% RMS difference) indicating some limitations to the Eclipse modeling in this case. The worst case estimates of uncertainty introduced by the signal decay for deliveries of 2, 5, and 10 min are 0.6%, 1.4%, and 2.8% respectively. Conclusions Reusable Presage sheets show promise for 2D dose measurement and as a radiochromic bolus for in vivo dose measurement. The current prototype is suitable for deliveries of length up to 5 min, where the uncertainty introduced by signal decay is anticipated to be ~1% (worst case 1.4%), or for longer deliveries where there is no temporal modulation (e.g. physical compensators, or open beams). Additionally, spatial resolution is limited by sheet thickness and scanner resolution, resulting in a practical resolution of 0.8 mm.

Collins, Cielle↗
DOE OSTI2014

An analysis of the uncertainty and bias in DCE-MRI measurements using the spoiled gradient-recalled echo pulse sequence

Purpose: The pharmacokinetic parameters derived from dynamic contrast-enhanced (DCE) MRI have been used in more than 100 phase I trials and investigator led studies. A comparison of the absolute values of these quantities requires an estimation of their respective probability distribution function (PDF). The statistical variation of the DCE-MRI measurement is analyzed by considering the fundamental sources of error in the MR signal intensity acquired with the spoiled gradient-echo (SPGR) pulse sequence. Methods: The variance in the SPGR signal intensity arises from quadrature detection and excitation flip angle inconsistency. The noise power was measured in 11 phantoms of contrast agent concentration in the range [0–1] mM (in steps of 0.1 mM) and in onein vivo acquisition of a tumor-bearing mouse. The distribution of the flip angle was determined in a uniform 10 mM CuSO{sub 4} phantom using the spin echo double angle method. The PDF of a wide range of T1 values measured with the varying flip angle (VFA) technique was estimated through numerical simulations of the SPGR equation. The resultant uncertainty in contrast agent concentration was incorporated in the most common model of tracer exchange kinetics and the PDF of the derived pharmacokinetic parameters was studied numerically. Results: The VFA method is an unbiased technique for measuringT1 only in the absence of bias in excitation flip angle. The time-dependent concentration of the contrast agent measured in vivo is within the theoretically predicted uncertainty. The uncertainty in measuring K{sup trans} with SPGR pulse sequences is of the same order, but always higher than, the uncertainty in measuring the pre-injection longitudinal relaxation time (T1{sub 0}). The lowest achievable bias/uncertainty in estimating this parameter is approximately 20%–70% higher than the bias/uncertainty in the measurement of the pre-injection T1 map. The fractional volume parameters derived from the extended Tofts model were found to be extremely sensitive to the variance in signal intensity. The SNR of the pre-injection T1 map indicates the limiting precision with which K{sup trans} can be calculated. Conclusions: Current small-animal imaging systems and pulse sequences robust to motion artifacts have the capacity for reproducible quantitative acquisitions with DCE-MRI. In these circumstances, it is feasible to achieve a level of precision limited only by physiologic variability.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

NREL Energy Models Examine the Potential for Wind and Solar Grid Integration (Fact Sheet)

As renewable energy generating sources, such as wind turbines and solar power systems, reach high levels of penetration in parts of the United States, the National Renewable Energy Laboratory (NREL) is helping the utility industry to peer into the future. Using software modeling tools that the lab developed, NREL is examining the future operation of the electrical grid as renewable energy continues to grow.

14 SOLAR ENERGY↗
DOE OSTI2015

NREL Analysis: Reimagining What's Possible for Clean Energy, Continuum Magazine, Summer 2015 / Issue 8; NREL (National Renewable Energy Laboratory)

This issue of Continuum Magazine covers the depth and breadth of NREL's ever-expanding analytical capabilities. For example, in one project we are leading national efforts to create a computer model of one of the most complex systems ever built. This system, the eastern part of the North American power grid, will likely host an increasing percentage of renewable energy in years to come. Understanding how this system will work is important to its success - and NREL analysis is playing a major role. We are also identifying the connections among energy, the environment and the economy through analysis that will point us toward a 'water smart' future.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2015

Eastern Renewable Generation Integration Study: Flexibility and High Penetrations of Wind and Solar; NREL (National Renewable Energy Laboratory)

Balancing wind and solar in a model is relatively easy. All you need to do is assume a very large system with infinite flexibility! But what if you don't have an infinitely flexible system? What if there are thousands of generators nestled in a handful of regions that are unlikely to change their operational practices? Would you still have enough flexibility to balance hundreds of gigawatts of wind and solar at a 5 minute level? At NREL, we think we can, and our industry partners agree. This presentation was presented at the IEEE Power and Energy Society General Meeting by Aaron Bloom, highlighting results of the Eastern Renewable Generation Integration Study.

14 SOLAR ENERGY↗
DOE OSTI2015

NREL Analysis: Reimagining What's Possible for Clean Energy, Continuum Magazine, Summer 2015 / Issue 8

This issue of Continuum Magazine covers the depth and breadth of NREL's ever-expanding analytical capabilities. For example, in one project we are leading national efforts to create a computer model of one of the most complex systems ever built. This system, the eastern part of the North American power grid, will likely host an increasing percentage of renewable energy in years to come. Understanding how this system will work is important to its success - and NREL analysis is playing a major role. We are also identifying the connections among energy, the environment and the economy through analysis that will point us toward a 'water smart' future.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗