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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Structural Analysis Results of Thermal, Operating and Seismic Analysis for Hanford Single-Shell Tank Integrity - 12261

Since Hanford's 149 Single-Shell Tanks (SSTs) are well beyond their design life, the U.S. Department of Energy has commissioned a state of the art engineering analysis to assess the structural integrity of the tanks to ensure that they are fit for service during the cleanup and closure phase. The structural integrity analysis has several challenging factors. There are four different tank sizes in various configurations that require analysis. Within each tank type there are different waste level and temperature histories, soil overburden depths, tank floor arrangements, riser sizes and locations, and other on-tank structures that need to be addressed. Furthermore, soil properties vary throughout the tank farms. This paper describes the structural integrity analysis that was performed for the SSTs using finite element models that incorporate the detailed design features of each tank type. The analysis was performed with two different models: an ANSYS static model for the Thermal and Operating Loads Analysis, and an ANSYS dynamic model for the seismic analysis. The TOLA analyses simulate the waste level and thermal history and it included a matrix of analysis cases that bounded the material property uncertainties. The TOLA also predicts the occurrence of concrete thermal degradations and cracking, reinforcement yielding, and soil plasticity. The seismic analysis matrix included uncertainty in waste properties, waste height and the soil modulus. In seismic analysis the tank concrete was modeled as a linear elastic material that was adjusted for the present day degraded conditions. Also, the soil was treated as a linear elastic material while special modeling techniques were used to avoid soil arching and achieve proper soil pressure on the tank walls. Seismic time histories in both the horizontal and vertical directions were applied to the seismic model. Structural demands from both Thermal and Operating Loads Analysis and seismic models were extracted in the form of section forces and moments for sections throughout the tank under the appropriate load combinations. These demands were evaluated against the American Concrete Institute (ACI) code requirements for nuclear safety-related concrete structures as defined in ACI-349-06. Structural integrity analysis of Hanford's Type II and Type III Single-Shell Tanks (SSTs) was performed using finite element models (ANSYS software) that incorporate the detailed design features of each tank type. The analysis was performed with two different models: a static model for the Thermal and Operating Loads Analysis, and a dynamic model for the seismic analysis. Structural demands from both Thermal and Operating Loads Analysis and seismic models were evaluated against the American Concrete Institute (ACI) code requirements for nuclear safety-related concrete structures as defined in ACI-349-06. The ratio of demand to capacity (D/C) was reported as a measure of structural integrity for the applicable ACI-349-06 load combinations. Although the Type II and Type III analysis matrix showed varying demands depending on the material combinations, all of the tank regions that are critical to structural stability passed the ACI 349-06 acceptance criteria. This was true for the conservative combination of maximum recorded thermal loads and maximum soil overburden depth combined with the analysis matrix of bounding material property combinations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1995

Aerospace safety advisory panel

The Aerospace Safety Advisory Panel (ASAP) monitored NASA's activities and provided feedback to the NASA Administrator, other NASA officials and Congress throughout the year. Particular attention was paid to the Space Shuttle, its launch processing and planned and potential safety improvements. The Panel monitored Space Shuttle processing at the Kennedy Space Center (KSC) and will continue to follow it as personnel reductions are implemented. There is particular concern that upgrades in hardware, software, and operations with the potential for significant risk reduction not be overlooked due to the extraordinary budget pressures facing the agency. The authorization of all of the Space Shuttle Main Engine (SSME) Block II components portends future Space Shuttle operations at lower risk levels and with greater margins for handling unplanned ascent events. Throughout the year, the Panel attempted to monitor the safety activities related to the Russian involvement in both space and aeronautics programs. This proved difficult as the working relationships between NASA and the Russians were still being defined as the year unfolded. NASA's concern for the unique safety problems inherent in a multi-national endeavor appears appropriate. Actions are underway or contemplated which should be capable of identifying and rectifying problem areas. The balance of this report presents 'Findings and Recommendations' (Section 2), 'Information in Support of Findings and Recommendations' (Section 3) and Appendices describing Panel membership, the NASA response to the March 1994 ASAP report, and a chronology of the panel's activities during the reporting period (Section 4).

Source record↗
DOE OSTI2020

Risk-Informed ATF and FLEX Analysis for an Enhanced Resilient BWR Under Design-Basis and Beyond-Design-Basis Accidents

This report documents the activities performed by the Idaho National Laboratory (INL) during fiscal year (FY) 2020 for the U.S. Department of Energy (DOE) Light Water Reactor Sustainability (LWRS) Program, Risk-Informed System Analysis (RISA) Pathway, Enhanced Resilient Plant (ERP) Systems research. The purpose of the RISA Pathway research and development is to support plant owner-operator decisions with the aim to improve the economics, reliability, and maintain the high levels of safety of current nuclear power plants over periods of extended plant operations. The concept of ERP refers to the combinations of accident-tolerant fuel (ATF), optimal use of diverse and flexible coping strategy (FLEX), enhancements to plant components and systems, and the incorporation of augmented or new passive cooling systems, as well as improved fuel cycle efficiency. The objective of the ERP research effort is to use the RISA methods and toolkit in industry applications, including methods development and early demonstration of technologies, in order to enhance existing reactors’ safety features (both active and passive) and to substantially reduce operating costs through risk-informed approaches to plant design modifications to the plant and their characterization. One main focus of the FY 2020 efforts documented in this report was to extend the analyses conducted in FYs 2018 and 2019 for a pressurized water reactor (PWR) to a boiling water reactor (BWR). The same analysis process, risk analysis approaches, and analysis tools as in the previous work for PWR were used for a generic BWR with near-term ATF cladding (i.e., Iron-Chromium-Aluminum [FeCrAl] cladding and Chromium [Cr]-coated cladding) designs under the postulated station blackout (SBO) and medium loss-of-coolant (MLOCA) accident scenarios. In addition, a FLEX model was developed and incorporated into a generic BWR probabilistic risk assessment (PRA) model using the INL-developed software tool, Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE), to assess the risk impact from FLEX. The other main focus of the FY 2020 efforts was to advance analysis methods, including developing dynamic approach for FLEX human reliability analysis (HRA) using the INL-developed software tool, Event Modeling Risk Assessment using Linked Diagrams (EMRALD), as well as developing a multicriterion benefit evaluation (MCBE) method for evaluating costs and benefits of safety enhancements in nuclear power plants (NPPs). As a case study, the MCBE method was applied to evaluate the costs and benefits brought by FLEX implementation.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2017

Status of the SAS4A/SASSYS-1 Safety Analysis Code

SAS4A/SASSYS-1 is a simulation tool used to perform deterministic analysis of anticipated events as well as design basis and beyond design basis accidents for advanced reactors. This report summarizes the current status of SAS4A/SASSYS-1, including the implementation of software quality assurance procedures for configuration management, new licenses, current users, and a gap assessment of the test suite. The existing copyright has been extended for an additional five years, which was essential so that Argonne can continue developing, distributing, and supporting the software for both domestic use and international collaborations. SAS4A/SASSYS-1 Version 5.2 was completed in March 2017 and released to users in May. The importance of SAS4A/SASSYS-1 maintenance reflects its relevance to a number of U.S. Department of Energy programs as well as domestic and international collaborations. External collaborations have also produced improvements in the SAS4A/SASSYS-1 code, and these are noted in this report. SAS4A/SASSYS-1 has a growing user base that continues to strengthen the promotion of advanced non-LWR reactor concepts. Additional users will help solidify DOE’s leadership role in fast reactor safety both domestically and in international collaborations.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2015

WE-G-BRA-06: Application of Systems and Control Theory-Based Hazard Analysis to Radiotherapy

Purpose: The process of delivering radiation occurs in a complex socio-technical system heavily reliant on human operators. Furthermore, both humans and software are notoriously challenging to account for in traditional hazard analysis models. High reliability industries such as aviation have approached this problem through using hazard analysis techniques grounded in systems and control theory. The purpose of this work is to apply the Systems Theoretic Accident Model Processes (STAMP) hazard model to radiotherapy. In particular, the System-Theoretic Process Analysis (STPA) approach is used to perform a hazard analysis of a proposed on-line adaptive cranial radiosurgery procedure that omits the CT Simulation step and uses only CBCT for planning, localization, and treatment. Methods: The STPA procedure first requires the definition of high-level accidents and hazards leading to those accidents. From there, hierarchical control structures were created followed by the identification and description of control actions for each control structure. Utilizing these control structures, unsafe states of each control action were created. Scenarios contributing to unsafe control action states were then identified and translated into system requirements to constrain process behavior within safe boundaries. Results: Ten control structures were created for this new CBCT-only process which covered the areas of hospital and department management, treatment design and delivery, and vendor service. Twenty three control actions were identified that contributed to over 80 unsafe states of those control actions resulting in over 220 failure scenarios. Conclusion: The interaction of people, hardware, and software are highlighted through the STPA approach. STPA provides a hierarchical model for understanding the role of management decisions in impacting system safety so that a process design requirement can be traced back to the hazard and accident that it is intended to mitigate. Varian Medical Systems, Inc.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Supplement to the NUBOW-3D Manual

The NUBOW-3D code (NUBOW) developed in 1978 is a custom FORTRAN analysis code that models the complex mechanical interaction of the fuel assemblies and the core restraint system in response to the effects of thermal expansion and irradiation swelling and creep. NUBOW-3D models the fuel assembly ducts as beams with springs representing the contact between ducts. The core temperature profile and neutron flux profiles are provided at various times during the planned operation of the reactor. NUBOW then calculates the changing shapes of the fuel assemblies and their equilibrium positions within the core restraints. An optional post-processing step calculates the reactivity changes based on new positions of the fuel assemblies using input displacement reactivity WORTHS. Understanding this reactivity change is a key feature to the inherent safety of a fast reactor core. NUBOW was developed to support the design of limited free bow core restraint systems. The NUBOW software was modified in 1987 but the documentation of the upgrades was not completed due to abrupt funding cuts. In the last few years, the software has been ported to a Windows platform using a current FORTRAN compiler and additional changes have been made including consolidating the code to a single executable. While the original NUBOW manual [1] written in 1978 provides an excellent description of the code and input parameters, it lacks the additional features added in the upgrades and in some cases describes features that are no longer operable. This report attempts to bridge the information gap between the original manual and the current state of the software.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Reassessing energy deposition for the ITER 5 MA vertical displacement event with an improved DINA model

The beryllium (Be) main chamber wall interaction during a 5 MA/1.8 T upward, unmitigated VDE scenario, first analysed in [J. Coburn et al., Phys. Scr. T171 (2020) 014076] for ITER, has been re-evaluated using the latest energy deposition analysis software. Updates to the DINA disruption model are summarized, including an improved numerical convergence for the 0D power balance, limitations on the safety factor within the plasma core, and the choice to maintain a constant plasma +halo poloidal cross-section. Such updates result in a broad halo region and higher radiated power fractions compared to previous models. The new scenario lasts for ~75 ms and deposits ~29 MJ of energy, with the radial distribution of parallel heat flux q‖(r)resembling an exponential falloff with an effective λ_q=75-198 mm. A maximum halo width w_h of 0.52 m at the outboard midplane is observed. SMITER field line tracing and energy deposition simulations calculate a q_{⊥,max} of ~83 MW/m^2 on the upper first wall panels (FWP). Heat transfer calculations with the MEMOS-U code show that the FWP surface temperature reaches ~1000 K, well below the Be melt threshold. Variations of this 5 MA scenario with Be im-purity densities from 0 to 3∙10^19 m^-3 also remain below the melt threshold despite differences in energy deposition and duration. These results are in contrast to the early study which predicted melt damage to the first wall [J. Coburn et al., Phys. Scr. T171 (2020) 014076], and emphasize the importance of accurate models for the halo width w_h and the heat flux distribution q‖(r)within that halo width. The 2020 halo model in DINA has been compared with halo current experiments on COMPASS, JET, and Alcator C-Mod, and the preliminary results build confidence in the broad halo width predictions. Results for the 5 MA VDE are compared with those for a 15 MA equivalent, generated using the new DINA model. At the higher current, significant melting of the upper FWP is to be expected.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1989

Predicting software reliability

A detailed look is given to software reliability techniques. A conceptual model of the failure process is examined, and some software reliability growth models are discussed. Problems for which no current solutions exist are addressed, emphasizing the very difficult problem of safety-critical systems for which the reliability requirements can be enormously demanding.

Littlewood, B.↗
NASA NTRS1994

Multimission Telemetry Visualization (MTV) system: A mission applications project from JPL's Multimedia Communications Laboratory

This paper describes the Multimission Telemetry Visualization (MTV) data acquisition/distribution system. MTV was developed by JPL's Multimedia Communications Laboratory (MCL) and designed to process and display digital, real-time, science and engineering data from JPL's Mission Control Center. The MTV system can be accessed using UNIX workstations and PC's over common datacom and telecom networks from worldwide locations. It is designed to lower data distribution costs while increasing data analysis functionality by integrating low-cost, off-the-shelf desktop hardware and software. MTV is expected to significantly lower the cost of real-time data display, processing, distribution, and allow for greater spacecraft safety and mission data access.

Koeberlein, Ernest, III↗
NASA NTRS2013

Human-rated Safety Certification of a High Voltage Robonaut Lithium-ion Battery

NASA's rigorous certification process is being followed for the R2 high voltage battery program for use of R2 on International Space Station (ISS). Rigorous development testing at appropriate levels to credible off-nominal conditions and review of test data led to design improvements for safety at the virtual cell, cartridge and battery levels. Tests were carried out at all levels to confirm that both hardware and software controls work. Stringent flight acceptance testing of the flight battery will be completed before launch for mission use on ISS.

Jeevarajan, Judith↗
NASA NTRS2016

Algorithms for Collision Detection Between a Point and a Moving Polygon, with Applications to Aircraft Weather Avoidance

This paper proposes mathematical definitions of functions that can be used to detect future collisions between a point and a moving polygon. The intended application is weather avoidance, where the given point represents an aircraft and bounding polygons are chosen to model regions with bad weather. Other applications could possibly include avoiding other moving obstacles. The motivation for the functions presented here is safety, and therefore they have been proved to be mathematically correct. The functions are being developed for inclusion in NASA's Stratway software tool, which allows low-fidelity air traffic management concepts to be easily prototyped and quickly tested.

Narkawicz, Anthony↗
NASA NTRSDate not supplied

Tutorial: Electrified Aircraft Propulsion Approaches for Modeling and Electrical Hardware-in-the-Loop Testing

This tutorial session outlines capabilities made available by the National Aeronautics and Space Administration for testing electrified aircraft propulsion (EAP) hardware and software prior to using turbomachinery. Removing these components from the experimentation process until necessary significantly reduces the development and testing costs and safety risks. Three facilities, the NASA Electric Aircraft Testbed (NEAT) and the Hybrid Propulsion Emulation Rig (HyPER) are unique facilities that provide the following capabilities: (i) the verification of megawatt-scale electrical and electromechanical system components at altitude, (ii) the verification of EAP control systems on sub-scale representative electromechanical architectures. The importance, operation, and specifications of each facility is described with detail. Provided examples of past testing showcase the abilities of each facility. Simple and complex methods for replicating the steady state and dynamical mechanical loading on the electrical power system are discussed

Electrified Aircraft Propulsion↗
NASA NTRS2026

Updates and Modernization of NASA’s Chemical Equilibrium with Applications (CEA) Code

NASA’s Chemical Equilibrium with Applications (CEA) code is a foundational tool for propulsion system analysis. It provides equilibrium chemistry, rocket performance, shock, and detonation calculations used across NASA and the broader aerospace community. NASA Engineering and Safety Center (NESC) Activity TI-22-01730 modernized the legacy CEA2 Fortran code into CEA v3, a Fortran 2008, object-oriented software package with expanded interface support, updated thermochemical data, improved maintainability, and substantially improved workflow integration. The modernized code preserves backward compatibility with legacy CEA input workflows while enabling direct use from modern analysis environments, including Python, C, MATLAB, and automated design studies.

Mark K Leader↗
NASA NTRS2026

Updates and Modernization of the Chemical Equilibrium with Applications (CEA) Code

NASA’s Chemical Equilibrium with Applications (CEA) code is a foundational tool for propulsion system analysis. It provides equilibrium chemistry, rocket performance, shock, and detonation calculations used across NASA and the broader aerospace community. NASA Engineering and Safety Center (NESC) Activity TI-22-01730 modernized the legacy CEA2 Fortran code into CEA v3, a Fortran 2008, object-oriented software package with expanded interface support, updated thermochemical data, improved maintainability, and substantially improved workflow integration. The modernized code preserves backward compatibility with legacy CEA input workflows while enabling direct use from modern analysis environments, including Python, C, MATLAB, and automated design studies.

Combustion↗
DOE OSTI2017

Developmental study of advanced HIS design method for digital I and C+HMIT of PWR plant - 277

A new conceptual frame of how to design and validate a digital HIS (human interface system) on an innovative numerical simulation basis is proposed for the support of plant operators' supervisory control of various types of automated complex NPPs (nuclear power plants). The proposed conceptual framework utilizes the object-oriented software for plant DiD (defense-in depth) risk monitor with the combination of nuclear reactor accident simulation by an advanced nuclear safety analysis code RELAP5/MOD4. The conceptual frame proposed in this paper will be applied for an example practice for the SBLOCA (small break loss of coolant accident) case of passive safety PWR (pressurized water reactor) AP1000. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

SymPLe 1131: A novel architectural solution for the realization of verifiable digital I and C systems and embedded digital devices - 387

One of the main reasons for the increasing popularity of FPGAs in embedded systems and digital I and C systems is that they provide many of the advantages from both hardware and software components. FPGAs provide configurability approaching that of SW, while at the same time delivering deterministic behavior of pure hardware solutions. However, with regard to Software Common Cause Failures (CCF), the use of FPGAs in digital I and C platforms should not be seen as plug-in remedy for reduction or elimination of CCF. To address CCF, we argue that it is not enough to manage the complexity of an I and C device or system, but we must also have the ability to constrain complexity (as needed) and rigorously reason about execution and device functionality. This paper presents the work done regarding an FPGA overlay architecture called SymPLe. SymPLe is designed to reduce the gap between software and hardware approaches for digital I and C systems and increases deterministic behavior and verifiability of the application, architecture and safety-critical system while reasoning about CCF. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗