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At least 361 records · Page 20

All sources NASA NTRS DOE OSTI

DOE OSTI2016

Modeling, Analysis, and Impedance Design of Battery Energy Stored Single-Phase Quasi-Z Source Photovoltaic Inverter System

The battery energy stored quasi-Z-source (BES-qZS) based photovoltaic (PV) power generation system combines advantages of the qZS inverter and the battery energy storage system. However, the second harmonic (2 ) power ripple will degrade the system's performance and affect the system's design. An accurate model to analyze the 2 ripple is very important. The existing models did not consider the battery, and with the assumption L1=L2 and C1=C2, which causes the non-optimized design for the impedance parameters of qZS network. This paper proposes a comprehensive model for single-phase BES-qZS-PV inverter system, where the battery is considered and without any restriction of L1, L2, C1, and C2. A BES-qZS impedance design method based on the built model is proposed to mitigate the 2 ripple. Simulation and experimental results verify the proposed 2 ripple model and design method.

Xue, Yaosuo↗

DOE OSTI2018

Reduction of Stored NOx with CO/H2 and Hydrocarbons: A Spatial Resolution Analysis

Lean NOx traps (LNT) are multi-function multi-component catalysts which operate in an integral and transient reactor mode to reduce NOx in the exhaust from diesel or lean-burn gasoline engines. This chapter addresses the regeneration phase of the LNT operation, discussing various types of reductants and reactions involved. We describe how reductants of different reactivity influence catalyst functions, reactions, and overall regeneration efficiency. The presented examples highlight the importance of understanding the spatial and temporal development of key reactions and their interplay to rationalize the global performance of practical LNTs which are generally honeycomb-shaped ceramic monoliths. The emphasis is on explaining global NOx removal performance (i.e., activity and selectivity) based on the insights gained through spatially resolved techniques, including initial distribution and redistribution of stored NOx; oxygen storage and reduction; transformation of feed reductants; and formation and utilization of reduction intermediates. Pathways leading to N2O and NH3 byproduct formation as well as mitigation strategies are also discussed.

Choi, Jae-Soon↗

DOE OSTI2015

Variable Electricity from Base-load Nuclear Power Plants Using Stored Heat

Restrictions on greenhouse gas emissions and growth of renewables change the price structure of electricity markets with more hours per year of low electricity prices and high electricity prices. This creates large economic incentives to (1) store energy at times of low electricity prices to produce electricity when prices are high and (2) couple base-load nuclear plants to heat storage to avoid selling electricity at times of low prices and increase electricity sales at times of high prices. Nuclear energy coupled with thermal energy storage has potentially superior economics to alternative energy storage technologies for peak electricity production because (1) heat storage is cheaper than electricity storage, (2) economics of scale for energy storage, (3) more storage cycles per year and (4) dispatchable electricity generation that avoids full depletion of energy storage systems. Nuclear with heat storage is potentially the enabling technology for a zero-carbon nuclear renewable electricity grid. The changing electricity market, nuclear thermal energy storage options, and market analysis using the Texas electricity grid as an example are described.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2018

System and method of storing and analyzing information

A system and method of storing and analyzing information is disclosed. The system includes a compiler layer to convert user queries to data parallel executable code. The system further includes a library of multithreaded algorithms, processes, and data structures. The system also includes a multithreaded runtime library for implementing compiled code at runtime. The executable code is dynamically loaded on computing elements and contains calls to the library of multithreaded algorithms, processes, and data structures and the multithreaded runtime library.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2019

Methods and systems for capturing and storing carbon dioxide

Methods and systems for capturing and storing carbon dioxide are disclosed. In some embodiments, the methods include the following: mixing materials including magnesium or calcium with one or more acids and chelating agents to form a magnesium or calcium-rich solvent; using the organic acids derived from biogenic wastes as acids or chelating agents; generating carbonate ions by reacting a gas including carbon dioxide with a carbonic anhydrase biocatalyst; reacting the solvent with the carbonate ions to form magnesium or calcium carbonates; recycling a solution containing the biocatalyst after forming magnesium or calcium carbonates for re-use in the generating step; using the magnesium and calcium carbonates as carbon neutral filler materials and using the silica product as green filler materials or inexpensive absorbents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

System and method of storing and analyzing information

Feo, John T.↗

DOE OSTI2022

Model Predictive Control of Dual-Mode Energy-Stored Quasi-Z-Source Photovoltaic System

The energy-stored quasi-Z-source inverter (ES-qZSI) has attracted much attention for photovoltaic (PV) power generations, due to its capability to stabilize the PV power fluctuations and other advantages of Z-source inverter. Traditional ES-qZSI suffers from poor operation at night or cloudy days when PV power is extremely low. In order to overcome that, this paper proposes a model predictive control (MPC) strategy for an improved dual-mode ES-qZSI, which is designed to support all-weather operation of PV power generation system. The system predictive models in both day and night operating modes are derived. And the control strategy based on MPC is disclosed to ensure the high-performance operation of the system. Simulation is carried out on PV power fluctuation in daytime and switching between the two modes, to verify the effectiveness of proposed control strategy.

Xue, Yaosuo↗

DOE OSTI2022

DenKv: Addressing Design Trade-offs of Key-value Stores for Scientific Applications

High-performance computing (HPC) facilities have employed flash-based storage tier near to compute nodes to absorb high I/O demand by HPC applications during periodic system-level checkpoints. To accelerate these checkpoints, proxy-based distributed key-value stores (PD-KVS) gained particular attention for their flexibility to support multiple backends and different network configurations. PD-KVS rely internally on monolithic KVS, such as LevelDB or RocksDB, to exploit the KV interface and query support. However, PD-KVS are unaware of the high redundancy factor in checkpoint data, which can be up to GBs to TBs, and therefore, tend to generate high write and space amplification on these storage layers. In this paper, we propose DenKv which is deduplication-extended node-local LSM-tree-based KVS. DenKv employs asynchronous partially inline dedup (APID) and aims to maintain the performance characteristics of LSM-tree-based KVS while reducing the write and space amplification problems. We implemented DenKv atop BlobDB and showed that our proposed solution maintains performance while reducing write amplification up to 2× and space amplification by 4× on average.

Khan, Awais↗

DOE OSTI2013

Development and Testing of Techniques for In-Ground Stabilization, Size Reduction and Safe Removal of Radioactive Wastes Stored in Large Containments in Burial Grounds - 13591

Radioactive waste materials, including Transuranic (TRU) wastes from laboratories have been stored below ground in large containments at a number of sites in the US DOE Complex, and at nuclear sites in Europe. These containments are generally referred to as caissons or shafts. The containments are in a range of sizes and depths below grade. The caissons at the DOE's Hanford site are cylindrical, of the order of 2,500 mm in diameter, 3,050 mm in height and are buried about 6,000 mm below grade. One type of caisson is made out of corrugated pipe, whereas others are made of concrete with standard re-bar. However, the larger shafts in the UK are of the order of 4,600 mm in diameter, 53,500 mm deep, and 12,000 below grade. This paper describes the R and D work and testing activities performed to date to evaluate the concept of in-ground size reduction and stabilization of the contents of large containments similar to those at Hanford. In practice, the height of the Test Facility provided for a test cell that was approximately 22' deep. That prevented a 'full scale mockup' test in the sense that the Hanford Caisson configuration would be an identical replication. Therefore, the project was conducted in two phases. The first phase tested a simulated Caisson with surrogate contents, and part of a Chute section, and the second phase tested a full chute section. These tests were performed at VJ Technologies Test Facility located in East Haven, CT, as part of the Proof of Design Concept program for studying the feasibility of an in-situ grout/grind/mix/stabilize technology for the remediation of four caissons at the 618-11 Burial Ground at US Department of Energy Hanford Site. The test site was constructed such that multiple testing areas were provided for the evaluation of various tools, equipment and procedures under conditions that simulated the Hanford site, with representative soils and layout dimensions. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

Examination of long-stored uranium metal

A small quantity of unirradiated uranium from Magnox fuel elements is currently held in archive storage. Some of these samples date back to the late fifties. This material has been stored, untreated, in unsealed containers in air at ambient temperature, humidity and pressure conditions. Such conditions are relevant to those that may exist in a passive storage facility. A sample of this material has been subject to optical, electron-optical and Raman spectroscopic examination to determine the extent of corrosion and the composition of corrosion product arising from long-term, low-temperature oxidation of uranium metal in air. The examinations have established that, even after a period in excess of 40 years, there was no observable spalling of uranium oxide from the sample during storage. The extent of oxidation of the metal, derived by SEM analysis, was slight and insignificant in relation to overall structural stability of the material. Raman spectroscopy data showed that the bulk of the oxide layer was comprised of hyper-stoichiometric UO{sub 2}, with U{sub 4}O{sub 9} being the dominant component. The oxygen/uranium ratio was observed to be decreased at the metal/oxide interface, with a very thin layer that consisted of mainly UO{sub 2} at the metal surface. At the oxide/air interface, a very thin U{sub 3}O{sub 8} layer was detected. U{sub 4}O{sub 9} is relatively mechanically stable, due to a significantly higher density than UO{sub 2} and U{sub 3}O{sub 8}. It is likely that the lower internal stresses in the thick U{sub 4}O{sub 9} layer have resulted in less oxide film cracking than would be expected from UO{sub 2} or U{sub 3}O{sub 8} and hence the low oxidation rate observed. These results suggest that storage of uranium metal in air over decades is a safe and credible option. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

RO concentrated water treatment equipment for risk reduction of contaminated water stored in tank in Fukushima NPS - 16655

At the Fukushima Daiichi Nuclear Power Station (NPS) site, concentrated waste water was stored in tanks, awaiting treatment to remove radionuclides using various multi-nuclide removal systems. To accelerate the treatment for risk reductions of radiation dose and tank leakage, we constructed reverse-osmosis (RO) concentrated water treatment equipment. The equipment consists of filters and five adsorbent vessels containing Cs-Sr simultaneous adsorbents with the removal ability of Sr being 1/1000(max) to 1/100(min), and the overall treatment capacity of 500 to 900 m{sup 3}/day. We developed a simulation code to calculate the Sr concentration of outlet water for each vessel in order to evaluate the bed life of the media. The simulation code makes it possible to plan when to change media in the vessels during the equipment operation. The successful treatment of concentrated waste water was conducted using the equipment from January to May 2015. Total amount of water treated was 82,194 m{sup 3}. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Low Level Radon Concentration and Radon Daughter Dose Monitoring in an Arid-zone Waste Store - 20081

Radioactive waste containing predominantly soil and rubble from the clean-up of a former uranium and thorium minerals processing research facility is currently stored at the Woomera Test Range in South Australia awaiting final disposal. Prior to commencing any manipulation of the nearly 10,000 waste drums (205 L or 55 gallon each), radon concentration monitoring and radon daughter dosimetry has been undertaken to (i) gain understanding of the temporal and spatial variation of radon and its daughters within the storage facility, which could provide insights into the radiological source term and (ii) confirm that radiological risks to workers are below the guideline values. A time series of nearly 12 months of detailed observations shows low level radon concentrations with annual average values that are slightly above the average radon concentrations in Australian homes. Peak values in summer are about three times higher than the annual average based on the CRM measurements. Both radon concentrations and annual effective dose are well below the regulatory limits. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2013

Neutrinos from Stored Muons nuSTORM: Expression of Interest

The nuSTORM facility has been designed to deliver beams of electron and muon neutrinos from the decay of a stored muon beam with a central momentum of 3.8 GeV/c and a momentum spread of 10%. The facility is unique in that it will: serve the future long- and short-baseline neutrino-oscillation programmes by providing definitive measurements of electron-neutrino- and muon-neutrino-nucleus cross sections with percent-level precision; allow searches for sterile neutrinos of exquisite sensitivity to be carried out; and constitute the essential first step in the incremental development of muon accelerators as a powerful new technique for particle physics. Of the world's proton-accelerator laboratories, only CERN and FNAL have the infrastructure required to mount nuSTORM. Since no siting decision has yet been taken, the purpose of this Expression of Interest (EoI) is to request the resources required to: investigate in detail how nuSTORM could be implemented at CERN; and develop options for decisive European contributions to the nuSTORM facility and experimental programme wherever the facility is sited. The EoI defines a two-year programme culminating in the delivery of a Technical Design Report.

43 PARTICLE ACCELERATORS↗

DOE OSTI2015

High stored-energy breakdown tests on electrodes made of stainless steel, copper, titanium and molybdenum

IRFM have conducted resilience tests on electrodes made of Cu, stainless steel 304L, Ti and Mo against breakdowns up to 170 kV and 300 J. The tests of the 10×10 cm{sup 2} electrodes have been performed at an electrode distance d=11 mm under vacuum (P∼5×10{sup −6} mbar). No great difference in voltage holding between the materials could be identified; all materials could reach a voltage holding between 140 and 170 kV over the 11 mm gap, i.e. results scatter within a ±10% band. After exposure to ∼10000 seconds of high-voltage (HV) on-time, having accumulated ∼1000 breakdowns, the electrodes were inspected. The anodes were covered with large and small craters. The rugosity of the anodes had increased substantially, that of the cathodes to a lesser extent. The molybdenum electrodes are least affected, but this does not show in their voltage holding capability. It is hypothesized that penetrating high-energy electrons from the breakdown project heat below the surface of the anode and cause a micro-explosion of material when melting point is exceeded. Polished electrodes have also been tested. The polishing results in a substantially reduced breakdown rate in the beginning, but after having suffered a relatively small number (∼100) of breakdowns, the polished electrodes behaved the same as the unpolished ones.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2015

Simulation of the dissipated and stored energy under deformation and failure of metallic materials

This work is devoted to the development of the statistical model of the structural defect evolution which was developed at the Institute of continuous media mechanics UB RAS. This model takes into account stochastic properties of the defect evolution process, nonlinear interaction of defects, and connection between microplasticity and damage accumulation. The obtained constitutive equations allow us to propose a model of the energy storage and dissipation in the process of plastic deformation and failure of metallic materials. The obtained relations were adapted for standard finite-element package. Applicability of this model was demonstrated in three-dimensional simulation of the strain localization and crack propagation in metals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2025

Summary of Graphite Data Stored within NDMAS

The Graphite Technology Development Project provides data to support the design of graphite core components within specific reactor service conditions of the next generation of high-temperature, gas-cooled nuclear reactors. Physical, mechanical, and thermal properties of nuclear grade graphite were characterized for specimens that were unirradiated, irradiated, and irradiated under various stress conditions. The material properties include diameter, length, mass, density, compressive strength, tensile strength, flexural strength, modulus, resistivity, thermal diffusivity, and thermal expansion coefficient. Baseline graphite specimens are unirradiated from different grades (2114, IG-110, NBG-17, NBG-18, and PCEA) and different types used in different characterization tests (compressive, flexural, tensile, one-inch cylinder, and quarter-inch cylinder). The Advanced Graphite Creep (AGC) irradiation specimens are from a much larger number of grades and cylinder types (creep, piggyback, and pencil). For baseline graphite, characterization data for 7,756 specimens extracted from thirteen graphite billets were captured to the NDMAS database. For AGC experiments, four irradiation campaigns have been completed: AGC-1, AGC-2, AGC-3, and AGC-4. The ongoing HDG-1 (High-Dose Graphite) experiment, which began irradiation with Cycle 168B on August 26, 2020, includes specimens previously irradiated in AGC-2 in addition to the specimens originally destined for AGC-5.. Besides the characterization data, the AGC data includes irradiation monitoring and physics data representing the irradiation conditions of AGC specimens. Currently, all data for AGC-1, AGC-2, and AGC-3 have been captured to the NDMAS database. Only AGC-4 pre-irradiation and irradiation monitoring data have been captured, and HDG-1 pre-irradiation data are in process of being captured for unirradiated specimens. To date, a total of 38,149 material property records have been captured into NDMAS database for baseline and AGC specimens. All characterization data are qualified for use according to their perspective data verification reports. For the AGC irradiation campaigns, a total of 41,502 qualified physics calculation records were added for AGC-1, AGC-2, and AGC-3. Finally, a total of 173,698,505 AGC irradiation monitoring data records (thermocouple temperature, gas flow rate, gas pressure, gas moisture, applied load, and specimen displacement) have been captured to NDMAS; the majority of those records (~94%) are qualified data records.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2013

Analytics-Driven Lossless Data Compression for Rapid In-situ Indexing, Storing, and Querying

The analysis of scientific simulations is highly data-intensive and is becoming an increasingly important challenge. Peta-scale data sets require the use of light-weight query-driven analysis methods, as opposed to heavy-weight schemes that optimize for speed at the expense of size. This paper is an attempt in the direction of query processing over losslessly compressed scientific data. We propose a co-designed double-precision compression and indexing methodology for range queries by performing unique-value-based binning on the most significant bytes of double precision data (sign, exponent, and most significant mantissa bits), and inverting the resulting metadata to produce an inverted index over a reduced data representation. Without the inverted index, our method matches or improves compression ratios over both general-purpose and floating-point compression utilities. The inverted index is light-weight, and the overall storage requirement for both reduced column and index is less than 135%, whereas existing DBMS technologies can require 200-400%. As a proof-of-concept, we evaluate univariate range queries that additionally return column values, a critical component of data analytics, against state-of-the-art bitmap indexing technology, showing multi-fold query performance improvements.

Jenkins, John↗

DOE OSTI2013

ALACRITY: Analytics-Driven Lossless Data Compression for Rapid In-Situ Indexing, Storing, and Querying. In: Transactions on Large-Scale Data- and Knowledge-Centered Systems X. Lecture Notes in Computer Science, vol 8220

High-performance computing architectures face nontrivial data processing challenges, as computational and I/O components further diverge in performance trajectories. For scientific data analysis in particular, methods based on generating heavyweight access acceleration structures, e.g. indexes, are becoming less feasible for ever-increasing dataset sizes. We present ALACRITY, demonstrating the effectiveness of a fused data and index encoding of scientific, floating-point data in generating lightweight data structures amenable to common types of queries used in scientific data analysis. We exploit the representation of floating-point values by extracting significant bytes, using the resulting unique values to bin the remaining data along fixed-precision boundaries. To optimize query processing, we use an inverted index, mapping each generated bin to a list of records contained within, allowing us to optimize query processing with attribute range constraints. Overall, the storage footprint for both index and data is shown to be below numerous configurations of bitmap indexing, while matching or outperforming query performance.

Compression Ratio↗