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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Visual Attention Allocation Between Robotic Arm and Environmental Process Control: Validating the STOM Task Switching Model

Fifty six participants time shared a spacecraft environmental control system task with a realistic space robotic arm control task in either a manual or highly automated version. The former could suffer minor failures, whose diagnosis and repair were supported by a decision aid. At the end of the experiment this decision aid unexpectedly failed. We measured visual attention allocation and switching between the two tasks, in each of the eight conditions formed by manual-automated arm X expected-unexpected failure X monitoring- failure management. We also used our multi-attribute task switching model, based on task attributes of priority interest, difficulty and salience that were self-rated by participants, to predict allocation. An un-weighted model based on attributes of difficulty, interest and salience accounted for 96 percent of the task allocation variance across the 8 different conditions. Task difficulty served as an attractor, with more difficult tasks increasing the tendency to stay on task.

STOM attention allocation model validation↗
DOE OSTI2020

ONIX: An open-source depletion code

Open Source software enables innovative, community-based software development. ONIX brings this concept to the field of depletion calculations. It is an open-source depletion software to be used for nuclear reactor simulations, for fissile material production analysis as well as for nuclear arms control applications. ONIX provides a module to solve the depletion equation using a Chebyshev Rational Approximation Method. For the generation of one-group cross sections, it includes a coupling interface for the open-source neutron transport code, OpenMC, as well as a module to read pre-computed values in a stand-alone mode. ONIX has special features to optimize nuclear data libraries, to update isomeric branching ratio during burnup, and to support automation of simulations for nuclear archaeology. In conclusion, ONIX has been validated against results from numerical and experimental benchmarks, and its results agree with other methods within expected error ranges.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2014

Phase 3 Trial of Domiciliary Humidification to Mitigate Acute Mucosal Toxicity During Radiation Therapy for Head-and-Neck Cancer: First Report of Trans Tasman Radiation Oncology Group (TROG) 07.03 RadioHUM Study

Purpose: To assess the impact of domicile-based humidification on symptom burden during radiation therapy (RT) for head-and-neck (H and N) cancer. Methods and Materials: From June 2007 through June 2011, 210 patients with H and N cancer receiving RT were randomized to either a control arm or to receive humidification using the Fisher and Paykel Healthcare MR880 humidifier. Humidification commenced on day 1 of RT and continued until Common Terminology Criteria for Adverse Events (CTCAE), version 3.0, clinical mucositis (CMuc) grade ≤1 occurred. Forty-three patients (42%) met a defined benchmark for humidification compliance and contributed to per protocol (PP) analysis. Acute toxicities, hospitalizations, and feeding tube events were recorded prospectively. The McMaster University Head and Neck Radiotherapy Questionnaire (HNRQ) was used for patient-reported outcomes. The primary endpoint was area under the curve (AUC) for CMuc grade ≥2. Results: There were no significant differences in AUC for CMuc ≥2 between the 2 arms. Humidification patients had significantly fewer days in hospital (P=.017). In compliant PP patients, the AUC for CTCAE functional mucositis score (FMuc) ≥2 was significantly reduced (P=.009), and the proportion who never required a feeding tube was significantly greater (P=.04). HNRQ PP analysis estimates also in the direction favoring humidification with less symptom severity, although differences at most time points did not reach significance. Conclusions: TROG 07.03 has provided efficacy signals consistent with a role for humidification in reducing symptom burden from mucositis, but the influence of humidification compliance on the results moderates recommendations regarding its practical utility.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Long-Term Results of a Randomized Trial in Locally Advanced Rectal Cancer: No Benefit From Adding a Brachytherapy Boost

Purpose/Objective(s): Mature data on tumor control and survival are presented from a randomized trial of the addition of a brachytherapy boost to long-course neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer. Methods and Materials: Between March 2005 and November 2008, 248 patients with T3-4N0-2M0 rectal cancer were prospectively randomized to either long-course preoperative CRT (50.4 Gy in 28 fractions, per oral tegafur-uracil and L-leucovorin) alone or the same CRT schedule plus a brachytherapy boost (10 Gy in 2 fractions). The primary trial endpoint was pathologic complete response (pCR) at the time of surgery; secondary endpoints included overall survival (OS), progression-free survival (PFS), and freedom from locoregional failure. Results: Results for the primary endpoint have previously been reported. This analysis presents survival data for the 224 patients in the Danish part of the trial. In all, 221 patients (111 control arm, 110 brachytherapy boost arm) had data available for analysis, with a median follow-up time of 5.4 years. Despite a significant increase in tumor response at the time of surgery, no differences in 5-year OS (70.6% vs 63.6%, hazard ratio [HR] = 1.24, P=.34) and PFS (63.9% vs 52.0%, HR=1.22, P=.32) were observed. Freedom from locoregional failure at 5 years were 93.9% and 85.7% (HR=2.60, P=.06) in the standard and in the brachytherapy arms, respectively. There was no difference in the prevalence of stoma. Explorative analysis based on stratification for tumor regression grade and resection margin status indicated the presence of response migration. Conclusions: Despite increased pathologic tumor regression at the time of surgery, we observed no benefit on late outcome. Improved tumor regression does not necessarily lead to a relevant clinical benefit when the neoadjuvant treatment is followed by high-quality surgery.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Information barrier experimental: Toward a trusted and open-source computing platform for nuclear warhead verification

Trusted measurement systems are critical for the verification of future arms-control treaties that involve confirming the authenticity of nuclear warheads on the basis of their radiation signatures. Several research efforts have produced prototype systems, but their designs are typically not published in detail, making it difficult to enable trust in these devices. The Information Barrier Experimental (IBX) is a new prototype built around the Red Pitaya computing platform using passive gamma spectroscopy. It is the first such platform designed to help a broad research community study vulnerabilities and define the required specifications for a common, trusted inspection system. It is low-cost, simple to assemble, and enables comprehensive hardware and software authentication studies. The device follows a digital data acquisition approach, which significantly reduces the number of components between scintillator and spectrum output. Finally, measurements demonstrate that this approach is technically feasible and produces excellent measurement results.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Neutron response characterization for an EJ299-33 plastic scintillation detector

Organic scintillation detectors have shown promise as neutron detectors for characterizing special nuclear materials in various arms-control and homeland security applications. Recent advances have yielded a new plastic scintillator - EJ299-33 - with pulse-shape-discrimination (PSD) capability. Plastic scintillators would have a much expanded range of deployment relative to liquids and crystals. Here in this paper, we present a full characterization of pulse height response to fission-energy neutrons for an EJ299-33 detector with 7.62-by-7.62-cm cylindrical active volume, and compare with an EJ309 liquid scintillator in the same assembly. Scintillation light output relations, energy resolutions, and response matrices are presented for both detectors. A Continuous spectrum neutron source, obtained via the bombardment of 27 Al with 7.44-MeV deuterons at the Edwards Accelerator Facility at Ohio University, was used for the measurement. A new procedure for evaluating and comparing PSD performance is presented which accounts for the effect of the light output relation on the ability to detect low energy neutrons. The EJ299-33 is shown to have considerable deficit in matrix condition, and in PSD figure of merit when compared to EJ309, especially when neutron energy is taken into account. Furthermore the EJ299 is likely to bring a modest PSD capability into a array of held applications that are not accessible to liquids or crystals.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Experimental demonstration and modeling of a robotic neutron detector with spectral and directional sensitivity for treaty verification

International safeguards and arms control agreements often require labor-intensive, intrusive onsite inspections to perform verification tasks. The ability to localize a neutron source and/or characterize a neutron field may be imperative for identifying anomalies. We are interested in the role of autonomous mobile robots, which, if designed properly, may be more effective and efficient and less intrusive than their human counterparts. Toward developing such a capability, we, for this study, have constructed the N-SpecDir Bot, comprised of three boron-coated straw detectors azimuthally-distributed within a cylinder of high-density polyethylene, which is mounted on an omni-directional robotic platform. Our N-SpecDir Bot is specifically designed to provide spectral and directional sensitivity, in addition to gross counts, by utilizing the signals from the three detectors. The detection system has been extensively characterized by MCNP modeling, which has been benchmarked to experiments conducted at the Princeton Plasma Physics Laboratory. We demonstrate the spectral and directional sensitivity experimentally and in simulation, and provide a simple yet robust method for directional measurements.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2025

Angular-spectral filtering of recoil protons for optimization of fast neutron imaging employing proton converters

Fast neutron imaging is an important capability for diverse applications such as inertial confinement fusion diagnostics, cargo security, nuclear nonproliferation and arms control, and industrial inspection. Traditional phosphor image plates can be enhanced for fast neutron imaging using hydrogenous plastic converters which allow fast neutrons to scatter off hydrogen nuclei to produce energetic protons that can be recorded by the image plate. However, protons emitted by image plates are not constrained in their emission angle, which contributes to the blur of the resulting image. Here, we investigate two methods that can alter the spatial extent of converted protons that deposit energy in the image plate: reducing the converter thickness, and introducing a proton filter between the plastic converter and image plate to reduce the contribution of lower-energy, off-axis protons to the image. Here we determine the optimal plastic converter thickness for maximizing the signal intensity to be 2–3 mm through Monte Carlo simulations, and we benchmark this result against experimental measurements with a deuterium-tritium (DT) neutron generator. Next, we evaluate the image smearing and signal loss for various converters to show that solely reducing the converter thickness has the expected effect of reducing the blur from proton image smearing of the sharpness of an edge recorded on the image plate at the cost of reducing the signal intensity. The use of a proton filter is shown to achieve a similar improvement of edge sharpness as reducing the converter thickness while also sacrificing the signal intensity. We conclude that the use of proton energy filtering can improve the sharpness of fast neutron images in situations where the converter thickness cannot be reduced below some practical minimum. For more intense neutron sources, the signal intensity is of less concern, and optimizing the resolution of the image plate and therefore of the imaging system could have greater value. In these applications, proton filters may allow for improved fast neutron imaging measurements.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Tools and Incentives for Implementing Codes of Ethics to Help Prevent the Reemergence of Chemical Weapons

Since the entry into force of the Chemical Weapons Convention (CWC) and the establishment of the Organisation for Prohibition of Chemical Weapons (OPCW) in 1997, 96% of the world’s declared stockpile, comprising 72,305 metric tons of chemical warfare agents have been destroyed. Despite this notable progress, the convergence of chemistry and biology brings new challenges to preventing chemical weapons production, as the technical capability to manipulate the chemistry of microorganisms has diffused beyond the chemical industry and academic research communities. The development and voluntary adoption by chemical practitioners around the world of ethical codes or guidelines, such as The Hague Ethical Guidelines and the Global Chemists’ Code of Ethics (GCCE) , are important steps in strengthening international nonproliferation efforts through their potential to impact the intent of the individual by normalizing ethical behavior. However, the simple act of adopting a code does not guarantee ethical behavior. Care must be taken to ensure those adopting the code understand specifically the behavior being asked of them, and they must be given ample opportunities to practice exercising those behaviors in low-risk situations and encouragement to keep trying when they fail. Furthermore, in small-to-medium chemical companies, concerns that adopting such measures could negatively impact profit margins may dissuade some business owners from voluntarily adopting ethical codes, while a country’s decision makers may not prioritize establishment of new regulatory mechanisms that could address some of these concerns. In this paper, factors that may positively influence a chemical company’s decision to adopt ethical guidelines, such as integration of social sustainability elements into frameworks and approaches to maintain social legitimacy in the eyes of the broader community, are explored. Voluntary adoption of ethical codes gives teeth to arms control regimes. By encouraging chemical companies to become engaged in the community around them and providing easy-to-use tools like scenario-based E-learning to enable remote engagement and facilitate understanding of the principles undergirding the GCCE, they actively participate in making the world a better place and minimizing the potential for reemergence of chemical weapons.

Small Chemical Companies, Codes of Ethics, E-learn↗
DOE OSTI2014

A zero-knowledge protocol for nuclear warhead verification

The verification of nuclear warheads for arms control involves a paradox: international inspectors will have to gain high confidence in the authenticity of submitted items while learning nothing about them. Proposed inspection systems featuring ‘information barriers’, designed to hide measurements stored in electronic systems, are at risk of tampering and snooping. Here we show the viability of a fundamentally new approach to nuclear warhead verification that incor-porates a zero-knowledge protocol, which is designed in such a way that sensitive information is never measured and so does not need to be hidden. We interrogate submitted items with energetic neutrons, making, in effect, differential measurements of both neutron transmission and emission. Calculations for scenarios in which material is diverted from a test object show that a high degree of discrimination can be achieved while revealing zero information. Our ideas for a physical zero-knowledge system could have applications beyond the context of nuclear disarmament. The proposed technique suggests a way to perform comparisons or computations on personal or confidential data without measuring the data in the first place.

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

A physical zero-knowledge object-comparison system for nuclear warhead verification

Zero-knowledge proofs are mathematical cryptographic methods to demonstrate the validity of a claim while providing no further information beyond the claim itself. The possibility of using such proofs to process classified and other sensitive physical data has attracted attention, especially in the field of nuclear arms control. Here we demonstrate a non-electronic fast neutron differential radiography technique using superheated emulsion detectors that can confirm that two objects are identical without revealing their geometry or composition. Such a technique could form the basis of a verification system that could confirm the authenticity of nuclear weapons without sharing any secret design information. More broadly, by demonstrating a physical zero-knowledge proof that can compare physical properties of objects, this experiment opens the door to developing other such secure proof-systems for other applications.

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

Producing two-dimensional dust clouds and clusters using a movable electrode for complex plasma and fundamental physics experiments

We report a Bidirectional Electrode Control Arm Assembly (BECAA) for precisely manipulating dust clouds levitated above the powered electrode in RF plasmas. The reported techniques allow the creation of perfectly 2D dust layers by eliminating off-plane particles by moving the electrode from outside the plasma chamber without altering the plasma conditions. Here, the tilting and moving of electrodes using BECAA also allows the precise and repeatable elimination of dust particles one by one to achieve any desired number of grains N without trial and error. Simultaneously acquired top and side view images of dust clusters show that they are perfectly planar or 2D. A demonstration of clusters with N = 1–28 without changing the plasma conditions is presented to show the utility of BECAA for complex plasma and statistical physics experimental design. Demonstration videos and 3D printable part files are available for easy reproduction and adaptation of this new method to repeatably produce 2D clusters in existing RF plasma chambers.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Physical cryptographic verification of nuclear warheads

Significance We provide a method for potentially solving one of the central problems in arms control: proving the authenticity of a nuclear warhead without revealing information about its construction. The proposal is the first, to our knowledge, to be proof-theoretically sound (i.e., unspoofable) and information-theoretically secure. The method uses a tomography technique which can resolve the spatial distribution of mass with isotopic specificity. The soundness and security emerge from an integral-geometric transform that is able to uniquely map 3D geometries from zero-dimensional point measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Nuclear Warhead Verification: A Review of Attribute and Template Systems

Verification of current nuclear arms control treaties between United States and Russia relies primarily on the verification of delivery vehicles. Warheads are counted indirectly via the delivery vehicles that they are associated with. As states move to lower numbers of nuclear weapons in their arsenals, verification will likely pose complex challenges. Most importantly, future nuclear disarmament treaties may place limits on the total number of nuclear weapons in the arsenals. Their verification would require inspections of individual nuclear warheads without revealing secret information. By confirming the authenticity of nuclear warheads and perhaps also of warhead components we show the verification challenge for future reductions in the nuclear arsenals. Our paper provides an overview of the development of verification systems, and highlights the challenges and the opportunities for future research in this area.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2019

A Cryptographic Escrow for Treaty Declarations and Step-by-Step Verification

The verification of arms-control and disarmament agreements requires states to provide declarations, including information on sensitive military sites and assets. There are important cases, however, where negotiations of these agreements are impeded because states are reluctant to provide any such data, because of concerns about prematurely handing over militarily significant information. To address this challenge, we present a cryptographic escrow that allows a state to make a complete declaration of sites and assets at the outset and commit to its content, but only reveal the sensitive information therein sequentially. Combined with an inspection regime, our escrow allows for step-by-step verification of the correctness and completeness of the initial declaration so that the information release and inspections keep pace with parallel diplomatic and political processes. We apply this approach to the possible denuclearization of North Korea. Such approaches can be applied, however, to any agreement requiring the sharing of sensitive information.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2022

Document-Based Nuclear Archaeology

Deeper reductions in the nuclear arsenals will require better understanding of historic fissile material management and production. The concept of “nuclear archaeology” has been considered since the 1990s to provide the tools and methods to develop independent production estimates, primarily based on nuclear forensic techniques. Here, we propose to add a framework for reconstructing the history of a nuclear program that complements traditional nuclear archaeology techniques by examining the role of operating records to support such an effort. As a test case, we use the JEEP II reactor, a 2 MW civilian research reactor at Norway’s Institute for Energy Technology (IFE), in operation for more than fifty years, however, recently shut down permanently. We have collected, analyzed, and started to preserve the reactor’s operating records, which exist on both analog and digital media, and to simulate parts of its history using OpenMC/ONIX neutronics calculations. Here, a particular focus of this project has been on digital data curation and preservation to confirm and maintain the integrity, authenticity, and provenance of these records. In developing guidelines for best practices that conform to existing standards for long-term digital preservation and curation, we hope this project can help lay the basis for future nuclear archaeology efforts to support nuclear arms control and disarmament.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2023

Ceci N’est Pas Une Bombe: Lessons from a Field Experiment Using Neutron and Gamma Measurements to Confirm the Absence of Nuclear Weapons

In March 2023, the UN Institute for Disarmament Research held a verification experiment that included a mockup onsite inspection at a former military facility in the municipality of Menzingen, Switzerland. The experiment included a visit to the site by an inspection team, accompanied by the host team. Among other activities, radiation measurements were used to confirm the non-nuclear nature of selected items stored onsite. In this paper, we discuss the neutron and gamma measurement systems used during the experiment and the inspection protocols followed to confirm the absence of nuclear weapons. Furthermore, results from the experiment and a laboratory reproduction are presented, before concluding with lessons learned for how absence-confirmation measurements can help support verification of future arms control agreements.

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

The history and outlook for seismic monitoring of nuclear explosions in the context of the Comprehensive Nuclear-Test-Ban Treaty

Modern methods of nuclear-explosion monitoring are vastly more capable than they were when underground nuclear testing began in the late 1950s, in part because a cycle of improvements in explosion monitoring in the 1960–80 period led to improvements in monitoring for earthquakes and other phenomena, which then led to a general growth in monitoring assets that in turn has been applied back to explosion monitoring. Practical experiences in nuclear-explosion monitoring, acquired during the era of active testing prior to finalization of the CTBT text in 1996, laid the basis for monitoring in support of this arms-control initiative. This article elaborates on the future of nuclear-test-monitoring technology, which can build upon an additional and remarkable growth of general monitoring assets that began in the 1990s, largely unrelated to the specifics of nuclear-test monitoring. A new cycle of improvements in earthquake monitoring is likely to improve monitoring for explosions. While it is not easy to quantify the degree of monitoring improvement afforded by such new assets, an example from North Korea indicates the improvement can be substantial.

99 GENERAL AND MISCELLANEOUS↗