Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Safety”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

Airspace Safety Threshold Study: Status Update to SC-228 DAA Safety Sub-Group

Realization of the expected proliferation of Unmanned Aircraft System (UAS) operations in the National Airspace System (NAS) depends on the development and validation of performance standards for UAS Detect and Avoid (DAA) Systems. The RTCA Special Committee 228 is charged with leading the development of draft Minimum Operational Performance Standards (MOPS) for UAS DAA Systems. NASA, as a participating member of RTCA SC-228, is committed to supporting the development and validation of draft requirements as well as the safety substantiation and end-to-end assessment of DAA system performance. A recent study conducted using NASA's ACES (Airspace Concept Evaluation System) simulation capability begins to address questions surrounding the development of draft MOPS for DAA systems. ACES analyses were conducted to determine: 1) the rate at which IFR aircraft encounter other IFR and VFR aircraft, and 2) the rate at which UAS aircraft encounter VFR aircraft. Five different separation thresholds were used (two for encounter and one each for well-clear, near mid-air collision, and closest point of approach). The results will be used by SC228 to inform decisions about the safety aspect of UAS DAA systems and future requirements development and validation efforts.

Risk ratio↗
DOE OSTI2015

Quantifying Safety Margin Using the Risk-Informed Safety Margin Characterization (RISMC)

The Risk-Informed Safety Margin Characterization (RISMC), developed by Idaho National Laboratory as part of the Light-Water Reactor Sustainability Project, utilizes a probabilistic safety margin comparison between a load and capacity distribution, rather than a deterministic comparison between two values, as is usually done in best-estimate plus uncertainty analyses. The goal is to determine the failure probability, or in other words, the probability of the system load equaling or exceeding the system capacity. While this method has been used in pilot studies, there has been little work conducted investigating the statistical significance of the resulting failure probability. In particular, it is difficult to determine how many simulations are necessary to properly characterize the failure probability. This work uses classical (frequentist) statistics and confidence intervals to examine the impact in statistical accuracy when the number of simulations is varied. Two methods are proposed to establish confidence intervals related to the failure probability established using a RISMC analysis. The confidence interval provides information about the statistical accuracy of the method utilized to explore the uncertainty space, and offers a quantitative method to gauge the increase in statistical accuracy due to performing additional simulations.

Grabaskas, David↗
NASA NTRS2022

Calculating Factors of Safety and Margins of Safety from Interaction Equations for Preloaded Bolts

This report presents the derivation of the factored interaction equations for preloaded bolts in two- or three-dimensional space. This is an extension of the previous work of the first author which covered factored interaction equations consisting of load or stress-ratios which were either solely constant or solely varying quantities. The factored interaction equations for preloaded bolts consist of an axial load-ratio that is a combination of a constant quantity, preload and thermal load at preload, and a varying quantity, tensile and bending loads, and was not covered under the previous work. Two forms of the factored interaction equations for preloaded bolts, arising from two perspectives, are presented and compared. Closed form solutions for the tensile, shear, and bending loads as functions of the other concurrent loads that produces zero margin of safety are presented.

interaction equations↗
NASA NTRS2016

Early Engagement of Safety and Mission Assurance Expertise Using Systems Engineering Tools: A Risk-Based Approach to Early Identification of Safety and Assurance Requirements

Decades of systems engineering practice have demonstrated that the earlier the identification of requirements occurs, the lower the chance that costly redesigns will needed later in the project life cycle. A better understanding of all requirements can also improve the likelihood of a design's success. Significant effort has been put into developing tools and practices that facilitate requirements determination, including those that are part of the model-based systems engineering (MBSE) paradigm. These efforts have yielded improvements in requirements definition, but have thus far focused on a design's performance needs. The identification of safety & mission assurance (S&MA) related requirements, in comparison, can occur after preliminary designs are already established, yielding forced redesigns. Engaging S&MA expertise at an earlier stage, facilitated by the use of MBSE tools, and focused on actual project risk, can yield the same type of design life cycle improvements that have been realized in technical and performance requirements.

Requirement↗
DOE OSTI2018

Trace element migration during UF4 bomb reduction: Implications to metal fuel production, worker health and safety, and nuclear forensics

Understanding the migration of trace contaminants during the production of U metal is vital for fabricating advanced nuclear fuels, for managing worker health and safety at foundry and processing facilities, and for advancing nuclear forensic science. A common method used to produce actinide metals is the bomb reduction of suitable U precursors. Here, we report the results of a series of experiments designed to quantitatively track the trace contaminants Th, Ca, and, Mg through a bomb reduction of UF4 using a vacuum induction furnace. In this series, UF4 charges were doped with increasing levels of elemental Th from 0-1000 ppm Th/U. Following reduction, the metal ingot products and the associated slag and crucibles were individually digested and analyzed using inductively coupled plasma-mass spectrometry. The results show that Th fractionation occurred at all concentrations but was most significant, and near quantitative, in samples starting with Th concentrations below 100 ppm. Thorium was found to incorporate into the slag and crucible in roughly equal proportions. A significant amount of U and Ca migrated into the crucible walls, each correlated with Mg migration from the MgO crucible to the U metal product.

Reilly, Dallas D.↗
DOE OSTI2018

NCRP Program Area Committee 3: Nuclear and Radiological Security and Safety [Update on the Ncrp Program Area Committee 3 Activities: Nuclear And Radiological Security and Safety]

The National Council on Radiation Protection and Measurements (NCRP) Program Area Committee (PAC) 3 covers the broad subject of nuclear and radiological security and safety and provides guidance and recommendations for response to nuclear and radiological incidents of both an accidental and deliberate nature. In 2017, PAC 3 Scientific Committee 3-1 completed the development of Guidance for Emergency Responder Dosimetry, and began development of a companion commentary on operational aspects of that guidance. PAC 3 members also organized the technical program for the 2017 Annual Meeting of the NCRP on “Assessment of National Efforts in Emergency Preparedness for Nuclear Terrorism: Is There a Need for Realignment to Close Remaining Gaps.” Based on discussions and presentations at the annual meeting, PAC 3 is working to develop a commentary on the subject that could serve as a roadmap for focusing our national efforts on the most pressing needs for preparing the nation for nuclear and radiological emergencies. PAC 3 is also engaged in active discussions, exploring the landscape of priority issues for its future activities. Lastly, an important consideration in this discussion is the extent of NCRP’s present and potential future resources to support the work of its scientific committees.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2017

Criticality Safety Evaluation of Standard Criticality Safety Requirements #1-520 g Operations in PF-4

Guidance has been requested from the Nuclear Criticality Safety Division (NCSD) regarding processes that involve 520 grams of fissionable material or less. This Level-3 evaluation was conducted and documented in accordance with NCS-AP-004 (Ref. 1), formerly NCS-GUIDE-01. This evaluation is being written as a generic evaluation for all operations that will be able to operate using a 520-gram mass limit. Implementation for specific operations will be performed using a Level 1 CSED, which will confirm and document that this CSED can be used for the specific operation as discussed in NCS-MEMO-17-007 (Ref. 2). This Level 3 CSED updates and supersedes the analysis performed in NCS-TECH-14-014 (Ref. 3).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1972

In-space propellant systems safety. Volume 3: System safety analysis

The primary objective was to examine from a system safety viewpoint in-space propellant logistic elements and operations to define the potential hazards and to recommend means to reduce, eliminate or control them. A secondary objective was to conduct trade studies of specific systems or operations to determine the safest of alternate approaches.

Source record↗
NASA NTRS1972

Manned space flight nuclear system safety. Volume 3: Reactor system preliminary nuclear safety analysis. Part 2: Accident Model Document (AMD)

The Accident Model Document is one of three documents of the Preliminary Safety Analysis Report (PSAR) - Reactor System as applied to a Space Base Program. Potential terrestrial nuclear hazards involving the zirconium hydride reactor-Brayton power module are identified for all phases of the Space Base program. The accidents/events that give rise to the hazards are defined and abort sequence trees are developed to determine the sequence of events leading to the hazard and the associated probabilities of occurence. Source terms are calculated to determine the magnitude of the hazards. The above data is used in the mission accident analysis to determine the most probable and significant accidents/events in each mission phase. The only significant hazards during the prelaunch and launch ascent phases of the mission are those which arise form criticality accidents. Fission product inventories during this time period were found to be very low due to very limited low power acceptance testing.

Source record↗
NASA NTRS1974

Bibliography on aircraft fire hazards and safety. Volume 2: Safety. Part 1: Key numbers 1 to 524

Bibliographic citations are presented to describe and define aircraft safety methods, equipment, and criteria. Some of the subjects discussed are: (1) fire and explosion suppression using whiffle balls, (2) ultraviolet flame detecting sensors, (3) evaluation of flame arrestor materials for aircraft fuel systems, (4) crash fire prevention system for supersonic commercial aircraft, and (5) fire suppression for aerospace vehicles.

Pelouch, J. J., Jr.↗
NASA NTRS2010

Range Safety for an Autonomous Flight Safety System

The Range Safety Algorithm software encapsulates the various constructs and algorithms required to accomplish Time Space Position Information (TSPI) data management from multiple tracking sources, autonomous mission mode detection and management, and flight-termination mission rule evaluation. The software evaluates various user-configurable rule sets that govern the qualification of TSPI data sources, provides a prelaunch autonomous hold-launch function, performs the flight-monitoring-and-termination functions, and performs end-of-mission safing

Lanzi, Raymond J.↗
NASA NTRS2023

NASA Engineering and Safety Center Technical Bulletin No. 23-01: Including Key Design Features in Safety-Critical Pyrotechnic Firing Circuits

Pyrotechnic systems often fall into a unique category in that inadvertent activation of these systems resulting from a fault and/or lack of safe margins can lead directly to loss of crew. For example, untimely activation of pyrotechnics used for a flight termination system could override an abort capability. Over the years, NASA and the military have learned lessons about safe pyrotechnic circuit design and test, many of which are codified. However, with NASA’s recent efforts to move toward a development model than leans more heavily on Commercial Partners these requirements have not always been directly levied on projects and in some cases been misinterpreted. This bulletin describes key safety features of pyrotechnic firing circuit design and provides rationale for inclusion of each feature.

Pyrotechnic Firing Curcuits↗