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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 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Thermoplastic Composite Lunar Tower Truss Structure: Design Development and Verification Plans

The National Aeronautics and Space Administration (NASA) Space Technology and Mission Directorate (STMD) is advancing thermoplastic composite (TPC) technologies for exploration missions. The Technology Development for Exploration Applications (TDEA) project goals are to develop and mature TPC materials, designs, analyses tools and techniques, and mature manufacturing processes. This includes development of manufacturing and joining approaches relevant to space environments. To these ends TDEA endeavors toward demonstrating a TPC truss structure for a lunar tower configuration. The design, predicated on robotic assembly, uses open section truss elements fused to a joint splice plate, without a structural adhesive. This presentation details the TDEA lunar truss structure design development approach including design heritage, the requirements established, the mechanical design and analyses, and thermal analyses demonstrating structural requirements conformance, as well as planned building block verification efforts either underway or planned. The mechanical analyses show the most severe environment is a moon-quake the truss dynamic responses. The thermal analyses show the extreme cold for on-orbit welding, the window for less severe on-orbit welding, as well as the large thermal gradients on the truss. The building block approach shown includes ultrasonic welding and lap shear coupon testing on various truss element thicknesses and layups. Knockdown factor determinations due to lunar dust contamination (simulated) and effects of welding in a vacuum are presented. The most highly loaded truss joint configuration sub-element verification test matrix is outlined. Lastly, plans to build, inspect, and test a 2-bay truss representative unit cell that is 1.5 meters by 1.5 meters by 3.0 meters tall are detailed.

Lunar Tower↗
NASA NTRSDate not supplied

A Formal Verification Framework for Runtime Assurance

The simplex architecture is an instance of Runtime Assurance (RTA) where a trusted component takes control of a safety-critical system when an untrusted component violates a safety property. This paper presents a formalization of the simplex RTA framework in the language of hybrid programs. A feature of this formal verification framework is that, for a given system, a specific instantiation can be created and its safety properties are guaranteed by construction. Instantiations may be kept at varying levels of generality, allowing for black box components, such as ML/AI-based controllers, to be modeled. The framework is written in the Prototype Verification System (PVS) using Plaidypvs, an embedding of differential dynamic logic in PVS. As a proof of concept, the framework is illustrated on an automatic vehicle braking system.

Runtime assurance↗
NASA NTRSDate not supplied

The Roman Space Telescope Optical System: Status, Test, and Verification Update

The Nancy Grace Roman Space Telescope (“Roman”) is NASA’s next flagship observatory. Launching in 2026, Roman will explore the nature of dark energy as well as expand the census of exoplanets in our galaxy via microlensing. Roman’s large field of view, agile survey capabilities, and excellent stability enable these scientific objectives, yet present unique challenges for the design, test, and verification of its optical system. Roman recently completed a comprehensive thermal vacuum test of the Spacecraft bus + Integrated Payload Assembly (SCIPA), followed by integrating the Outer Barrel Assembly (OBA), Solar Array Sunshield (SASS), and Deployable Aperture Cover (DAC) with SCIPA to complete the Observatory. This paper will present an overview of the thermal vacuum optical testing as well as a status of the optical system performance and verification.

Matthew Bolcar↗
DOE OSTI2012

A Spectral Verification of the HELIOS-2 Lattice Physics Code

Core modeling of the Advanced Test Reactor (ATR) at INL is currently undergoing a significant update through the Core Modeling Update Project1. The intent of the project is to bring ATR core modeling in line with today’s standard of computational efficiency and verification and validation practices. The HELIOS-2 lattice physics code2 is the lead code of several reactor physics codes to be dedicated to modernize ATR core analysis. This presentation is concerned with an independent verification of the HELIOS-2 spectral representation including the slowing down and thermalization algorithm and its data dependency. Here, we will describe and demonstrate a recently developed simple cross section generation algorithm based entirely on analytical multigroup parameters for both the slowing down and thermal spectrum. The new capability features fine group detail to assess the flux and multiplication factor dependencies on cross section data sets using the fundamental infinite medium as an example.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2012

Safeguards Verification Measurements using Laser Ablation, Absorbance Ratio Spectrometry in Gaseous Centrifuge Enrichment Plants

Laser Ablation Absorbance Ratio Spectrometry (LAARS) is a new verification measurement technology under development at the US Department of Energy’s (DOE) Pacific Northwest National Laboratory (PNNL). LAARS uses three lasers to ablate and then measure the relative isotopic abundance of uranium compounds. An ablation laser is tightly focused on uranium-bearing solids producing a small plume containing uranium atoms. Two collinear wavelength-tuned spectrometry lasers transit through the plume and the absorbance of U-235 and U-238 isotopes are measured to determine U-235 enrichment. The measurement has high relative precision and detection limits approaching the femtogram range for uranium. It is independent of chemical form and degree of dilution with nuisance dust and other materials. High speed sample scanning and pinpoint characterization allow measurements on millions of particles/hour to detect and analyze the enrichment of trace uranium in samples. The spectrometer is assembled using commercially available components at comparatively low cost, and features a compact and low power design. Future designs can be engineered for reliable, autonomous deployment within an industrial plant environment. Two specific applications of the spectrometer are under development: 1) automated unattended aerosol sampling and analysis and 2) on-site small sample destructive assay measurement. The two applications propose game-changing technological advances in gaseous centrifuge enrichment plant (GCEP) safeguards verification. The aerosol measurement instrument, LAARS-environmental sampling (ES), collects aerosol particles from the plant environment in a purpose-built rotating drum impactor and then uses LAARS-ES to quickly scan the surface of the impactor to measure the enrichments of the captured particles. The current approach to plant misuse detection involves swipe sampling and offsite analysis. Though this approach is very robust it generally requires several months to obtain results from a given sample collection. The destructive assay instrument, LAARS-destructive assay (DA), uses a simple purpose-built fixture with a sampling planchet to collect adsorbed UF6 gas from a cylinder valve or from a process line tap or pigtail. A portable LAARS-DA instrument scans the microgram quantity of uranium collected on the planchet and the assay of the uranium is measured to ~0.15% relative precision. Currently, destructive assay samples for bias defect measurements are collected in small sample cylinders for offsite mass spectrometry measurement.

Enrichment Monitoring↗
DOE OSTI2012

NGSI: IAEA Verification of UF6 Cylinders

The International Atomic Energy Agency (IAEA) is often ignorant of the location of declared, uranium hexafluoride (UF6) cylinders following verification, because cylinders are not typically tracked onsite or off. This paper will assess various methods the IAEA uses to verify cylinder gross defects, and how the task could be ameliorated through the use of improved identification and monitoring. The assessment will be restricted to current verification methods together with one that has been applied on a trial basis—short-notice random inspections coupled with mailbox declarations. This paper is part of the NNSA Office of Nonproliferation and International Security’s Next Generation Safeguards Initiative (NGSI) program to investigate the concept of a global monitoring scheme that uniquely identifies and tracks UF6 cylinders.

cylinder monitoring tracking IAEA↗
DOE OSTI2012

Safeguards Verification Measurements using Laser Ablation, Absorbance Ratio Spectrometry in Gaseous Centrifuge Enrichment Plants

Laser Ablation Absorbance Ratio Spectrometry (LAARS) is a new verification measurement technology under development at the US Department of Energy (DOE) Pacific Northwest National Laboratory (PNNL). LAARS uses three lasers to ablate and then measure the relative isotopic abundance of uranium compounds. An ablation laser is tightly focused on uranium-bearing solids, producing a small atomic uranium vapor plume. Two collinear wavelength-tuned spectrometry lasers transit through the plume and the absorbance of U-235 and U-238 isotopes are measured to determine U-235 enrichment. The measurement is independent of chemical form and degree of dilution with nuisance dust and other materials. LAARS has high relative precision and detection limits approaching the femtogram range for U-235. The sample is scanned and assayed point-by-point at rates reaching 1 million measurements/hour, enabling LAARS to detect and analyze uranium in trace samples. The spectrometer is assembled using primarily commercially available components and features a compact design and automated analysis.Two specific gaseous centrifuge enrichment plant (GCEP) applications of the spectrometer are currently under development: 1) LAARS-Environmental Sampling (ES), which collects and analyzes aerosol particles for GCEP misuse detection and 2) LAARS-Destructive Assay (DA), which enables onsite enrichment DA sample collection and analysis for protracted diversion detection. The two applications propose game-changing technological advances in GCEP safeguards verification.

Uranium Enrichment Laser Safeguards↗
DOE OSTI2015

Systems Approach to Arms Control Verification

Using the decades of experience of developing concepts and technologies for verifying bilateral and multilateral arms control agreements, a broad conceptual systems approach is being developed that takes into account varying levels of information and risk. The IAEA has already demonstrated the applicability of a systems approach by implementing safeguards at the State level, with acquisition path analysis as the key element. In order to test whether such an approach could also be implemented for arms control verification, an exercise was conducted in November 2014 at the JRC ITU Ispra. Based on the scenario of a hypothetical treaty between two model nuclear weapons states aimed at capping their nuclear arsenals at existing levels, the goal of this exercise was to explore how to use acquisition path analysis in an arms control context. Our contribution will present the scenario, objectives and results of this exercise, and attempt to define future workshops aimed at further developing verification measures that will deter or detect treaty violations.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2016

Verification of a Configuration Space Method for Evaluating the All-Orders Linear Kinetic Plasma Response to RF Power

Progress towards verification of a configuration space algorithm for evaluating the linear kinetic plasma current response to applied radio-frequency power is presented. This follows a previously published [1] verification of the parallel-only response, by verifying the perpendicular response required for much of the ion-and electron-cyclotron range of frequencies. In particular, we use the Colestock-Kashuba fast-wave to ion-Bernstein-wave benchmark [2] where we show that the Kinetic-J computational kernel is able to reproduce a known reference solution calculated via the AORSA full-wave code [3]. We also discuss the computational and scaling aspects of this novel approach, as well as the difficulties presented by the temporal scales in this multi-species problem.

Green, David↗
DOE OSTI2018

Verification of a Numerical Model of the Offshore Wind Turbine from the Alpha Ventus Wind Farm Within OC5 Phase III: Preprint

The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project, is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project analyzes the Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. This paper shows results of the verification of the OWT models (code-to-code comparison). A subsequent publication will focus on their validation (comparison of simulated results to measured physical system response data). Based on the available data, the participants of Phase III set up numerical models of the OWT in their simulation tools. It was necessary to verify and to tune these models. The verification and tuning were performed against an OWT model available at the University of Stuttgart - Stuttgart Wind Energy (SWE) and documentation provided by Senvion and OWEC Tower. A very good match was achieved between the results from the reference SWE model and models set up by OC5 Phase III participants.

17 WIND ENERGY↗
DOE OSTI2019

Field programmable gate array bitstream verification

Described herein are various technologies pertaining to confirming an integrity of a FPGA. A verifier circuit is placed into an FPGA bitstream to enable external verification of the FPGA configuration in real time without requiring readout of the FPGA configuration itself. Number generators are utilized to generate a key which is shared between the FPGA and an external verification component (VC). The key is utilized to configure an initial state of sequence registers respectively located on both the FPGA and the VC. When the FPGA is operating with an approved configuration, output from the sequence registers at the FPGA and the VC are the same.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Verification and Validation of Systems in which AI is a Key Element

Many systems are being considered in which artificial intelligence (AI) will be a key element. Failure of an AI element can lead to system failure, hence the need for AI verification and validation (V&V). This article addresses V&V of such a system, focusing on the issues created by characteristics of AI that make V&V challenging. The element(s) containing AI capabilities is treated as a subsystem and V&V is conducted on that subsystem and its interfaces with other elements of the system under study, just as V&V would be conducted on other subsystems. That is, the high-level definitions of verification and of validation do not change for systems containing one or more AI elements. However, AI V&V challenges require approaches and solutions beyond those for conventional or traditional (those without AI elements) systems. This article provides an overview of how machine learning components/subsystems “fit” in the systems engineering framework (Section 1), identifies characteristics of AI subsystems that create challenges in their V&V (Section 2), describes those challenges (Section 3) and provides some potential solutions (Section 4).

Pullum, Laura↗
DOE OSTI2021

(Paper) TRIPWIRE: Multi-modal Distributed Sensing For Repository Verification

Underground geological repositories for storing used nuclear fuel are being planned and developed around the world. Research is being performed to understand technical aspects of sealing entombed materials and underground repositories to ensure the radiological and nuclear materials remain contained. To support safeguards verification for these facilities research at Idaho National Laboratory (INL) is underway to develop and demonstrate a multi-modal sensor system, TRIPWIRE, for containment verification in inaccessible radiological and nuclear waste repositories. The TRIPWIRE system will continuously monitor ionizing radiation and electromagnetic fields in the vicinity of emplaced nuclear materials buried in a repository, reporting on disturbances with a real-time alarm control station. The system will use long-length scintillating fiber bundles (SFBs) to perform area radiation monitoring; these will be coupled to kilometer-scale multimodal optical communication fibers – all light sensors and electronic components used with this system will be located above ground. Electromagnetic fields, and changes in local dielectric conditions caused by intrusion and soil movement, will be monitored using commercial grade, ported "leaky" coaxial cables (PCCs), with control electronics also located above ground. Tamper-indicating self-diagnostic assessments will be done using optical and electronic time domain reflectometry in the SFBs and PCCs, respectively. The result will be a long, kilometer-scale multi-modal SFB-PCC system. Simulation and modeling are being used to inform the work and a demonstration of the system's utility is planned at a nuclear storage facility in the future.

98 - NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL↗
DOE OSTI2024

Demonstration and Verification of Thermo-Mechanical Bowing in a Limited Free-Bow SFR Concept Using MOOSE

Core bowing due to thermal gradients and irradiation induced swelling and creep introduces significant reactivity feedback effects in liquid metal-cooled fast spectrum reactors. During startup, normal operations, and transient events, differential thermal and flux gradients cause expansion, creep, and swelling, which results in bowing in preferential directions depending on local material properties and load-pad and restraint-ring design. The bowing phenomenon produces negative reactivity during accident conditions provided the restraint system has been properly designed to optimally guide the deformation outwards in the active core region. Under the Department of Energy Nuclear Energy Advanced Modeling and Simulation program, a Multiphysics Object Oriented Simulation Environment (MOOSE)-based multiphysics approach to model core bowing is being developed. The present work expands on previous modeling of simpler International Atomic Energy Agency (IAEA) verification problems with these tools by modeling IAEA Verification Problem 4, which involves a symmetric sector of a reactor core with ducted assemblies undergoing differential thermal expansion due to thermal gradients bowing outward with duct-to-duct contact. This model is available on the National Reactor Innovation Center Virtual Test Bed repository. This example was verified against benchmark participant results, which includes bowing deformation evaluation and duct-to-duct interactions at load pads with mechanical contact.

22 - GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2011

Software Verification and Validation Plan Activities, 2011, Project Number: N6423, SAPHIRE Version 8

The SV&V Plan experienced changes over the past year to bring it into the operational software life cycle of SAPHIRE 8 and to maintain its sections on design features. Peer review of the SVVP with the former IV&V members identified the need for the operational use of metrics as a tool for quality maintenance and improvement. New tests were added to the SVVP to verify the operation of the new design features incorporated into SAPHIRE 8. Other additions to the SVVP were the addition of software metrics and the PDR and CDR processes. Audit support was provided for the NRC Technical Manager and Project Manager for the NRC OIG Audit performed throughout 2011. The SVVP is considered to be an up to date reference and useful roadmap of verification and validation activities going forward.

42 ENGINEERING↗
NASA NTRSDate not supplied

Formal Verification of Termination Criteria for First-Order Recursive Functions

This paper presents a formalization of several termination criteria for first-order recursive functions. The formalization, which is developed in the Prototype Verification System (PVS), includes the specification and proof of equivalence of semantic termination, Turing termination, size change principle, calling context graphs, and matrix-weighted graphs. These termination criteria are defined on a computational model that consists of a basic functional language called PVS0, which is an embedding of recursive first-order functions. Through this embedding, the native mechanism for checking termination of recursive functions in PVS could be soundly extended with semi-automatic termination criteria such as calling contexts graphs. As a proof of concept, this paper illustrates how such an extension can be implemented using proof strategies based on computational reflection.

Formal Verification↗
DOE OSTI2018

OpenMP 4.5 Validation and Verification Suite for Device Offload

OpenMP has been widely adopted for shared memory systems for over a decade. With the heterogeneity trend in architectures rapidly growing, the programming model needed to evolve such that applications could not only be ported to traditional CPUs but also to accelerators often acting as discrete or integrated devices to CPUs. To that end, OpenMP started to provide support for heterogeneous systems since 2013 when the version 4.0 of the specification was ratified. OpenMP 4.5 is being enhanced to cover major requirements of Exascale Computing Project (ECP) applications. As a result it is time-critical to ensure that the implementations of the 4.5 features are correct and conforming to the specification. This paper focuses on building a Validation and Verification testsuite that will test and present results for several offloading features implemented in compilers such as Clang, IBM XL C/C++, CCE, and GCC. We have results for our testsuite on TITAN, Summitdev and Summit at the Oak Ridge National Lab. We will highlight some of the ambiguities we encountered in the process of validating and verifying feature implementations. We also make the testsuite available for anyone to use and will walk the readers through the infrastructure and the workflow of the testsuite. A website has been built to capture our efforts narrated in this paper https://crpl.cis.udel.edu/ompvvsollve.

99 GENERAL AND MISCELLANEOUS↗