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96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
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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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Failure Mechanism Traceability and Application in Human System Interface of Nuclear Power Plants using RESHA
In recent years, there has been considerable effort to modernize existing and new nuclear power plants with digital instrumentation and control systems (DI&C). However, there has also been considerable concern both by industry and regulatory bodies for the risk and consequence analysis of these systems. Of particular concern are digital common cause failures (CCFs) specifically related to software defects. These “misbehaviors” by the software can occur in both the control and monitoring of a system. While many new methods have been proposed to identify potential software failure modes, such as Systems-theoretic Process Analysis (STPA), Hazard and Consequence Analysis for Digital Systems (HAZCADS), etc., these methods are focused primarily on the control action pathway of a system. In contrast, the information feedback pathway lacks unsafe control actions (UCAs), which are typically related to software basic events; thus, assessment of software basic events in such systems is unclear. In this work, we present the idea of intermediate processors and unsafe information flow (UIF) to help safety analysts trace failure mechanisms in the feedback pathway and how they can be integrated into a fault tree for improved assessment capability. The concepts presented are demonstrated in two comprehensive case studies, a smart sensor integrated platform for unmanned autonomous vehicles and another on a representative advanced human system interface (HSI) for safety critical plant monitoring. The qualitative software basic events are identified, and a fault tree analysis is conducted based on a modified Redundancy-guided Systems-theoretic Hazard Analysis (RESHA) methodology. The case studies demonstrate the use of UIF and intermediate processors in the fault tree to improve traceability of software failures in highly complex digital instrumentation feedback. The improved method can also clarify fault tree construction when multiple component dependencies are present in the system.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Failure Mechanism Traceability and Application in Human System Interface of Nuclear Power Plants using RESHA
In recent years, there has been considerable effort to modernize existing and new nuclear power plants with digital instrumentation and control systems (DI&C). However, there has also been considerable concern both by industry and regulatory bodies for the risk and consequence analysis of these systems. Of particular concern are digital common cause failures (CCFs) specifically related to software defects. These “misbehaviors” by the software can occur in both the control and monitoring of a system. While many new methods have been proposed to identify potential software failure modes, such as Systems-theoretic Process Analysis (STPA), Hazard and Consequence Analysis for Digital Systems (HAZCADS), etc., these methods are focused primarily on the control action pathway of a system. In contrast, the information feedback pathway lacks unsafe control actions (UCAs), which are typically related to software basic events; thus, assessment of software basic events in such systems is unclear. In this work, we present the idea of intermediate processors and unsafe information flow (UIF) to help safety analysts trace failure mechanisms in the feedback pathway and how they can be integrated into a fault tree for improved assessment capability. The concepts presented are demonstrated in two comprehensive case studies, a smart sensor integrated platform for unmanned autonomous vehicles and another on a representative advanced human system interface (HSI) for safety critical plant monitoring. The qualitative software basic events are identified, and a fault tree analysis is conducted based on a modified Redundancy-guided Systems-theoretic Hazard Analysis (RESHA) methodology. The case studies demonstrate the use of UIF and intermediate processors in the fault tree to improve traceability of software failures in highly complex digital instrumentation feedback. The improved method can also clarify fault tree construction when multiple component dependencies are present in the system.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
New generation of data acquisition and data storage systems of the IBR-2 reactor spectrometers complex
The paper presents an overview of works on the creation of data acquisition and data storage systems, which have been carried out in the Department of the IBR-2 spectrometers complex (DCS) of the Frank Laboratory of Neutron Physics (FLNP) over the past 15 years (before, during, and after the modernization of the IBR-2 reactor). These systems represent a unified set of identical (from the viewpoint of hardware) modules limited in type but functionally complete, wherein distinctions in parameters, functional capabilities, encoding, correction and preliminary data processing procedures specific to each spectrometer are realized on the level of microprograms, electronic tables, and integrated software control system.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Preliminary System Interface Failure Mode Analysis for Two Advanced Reactors
This study explores two distinct Balance of Plant (BOP) configurations: the Rankine cycle for a sodium-cooled fast reactor (SFR) and the Brayton cycle for a gas-cooled reactor (GCR). As representative designs, the Power Reactor Innovative Small Module (PRISM) by GE Hitachi Nuclear Energy was selected for the SFR, while the Gas Turbine Modular Helium Reactor (GT MHR) by General Atomics was chosen for the gas-cooled reactor. Both configurations were adapted to deliver high-quality heat for industrial applications. A Failure Modes and Effects Analysis (FMEA) was conducted for each system to identify critical failure modes affecting key components. This study marks the first phase of a two-step design optimization approach, integrating FMEA into the design process. Based on the analysis, design modifications and mitigation strategies were proposed to enhance system resilience. The second phase, to be detailed in a subsequent report, will focus on the role of the control system in mitigating these failures. The FMEA serves as a foundation for defining the control topology, ensuring system resilience against component failures that could compromise essential functions, such as electricity and heat production.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Reactor System Facility Modification to Detect Compromised Human Machine Interfaces
This study focuses on a multi-layered Industrial Control System (ICS)/Operational Technology (OT) security architecture to aid in the discovery and mitigation of compromised Human Machine Interface (HMI)/Instrumentation & Control (I&C) based systems for modifying a prototypical reactor condition test facility called the Flowing Autoclave System (FAS) at Idaho National Laboratory (INL). This is achieved through a three-layered combination of network security solutions, hash-based algorithms, and blockchain technologies. Hash algorithms are mathematical functions used to generate a predetermined set of fixed-length values. They are widely used in computer security to verify the integrity of system information and data, both on a local network and the wider internet. Even small amounts of unauthorized system modification will cause the hash algorithm to output a set of characters that deviate significantly from its original value. Assisting secure hash functions, blockchain technology is a secure and distributed technology used to provide an immutable set of records replicated on all devices within a decentralized network. Blockchain offers a cost-effective solution to detect system compromise by providing a traceable breadcrumb trail of all network activity and data modification happening on a system. If both are used in conjunction with network monitoring tools, the integration of this three-pronged approach can become an asset in detecting suspected system compromises before any real damage can occur.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Calreticulin discriminates the proximal region at the N-glycosylation site of Glc1Man9GlcNAc2 ligand
Calreticulin (CRT) is well known as a lectin-like chaperone that recognizes Glc1Man9GlcNAc2 (G1M9)-glycoproteins in the endoplasmic reticulum (ER). However, whether CRT can directly interact with the aglycone moiety (protein portion) of the glycoprotein remains controversial. To improve our understanding of CRT interactions, structure-defined G1M9-derivatives with different aglycones (–OH, –Gly–NH{sub 2}, and –Gly–Glu–{sup t}Bu) were used as CRT ligands, and their interactions with recombinant CRT were analyzed using thermal shift analysis. The results showed that CRT binds strongly to a G1M9-ligand in the order –Gly–Glu–{sup t}Bu > –Gly–NH{sub 2} > –OH, which is the same as that of the reglucosylation of Man9GlcNAc2 (M9)-derivatives by the folding sensor enzyme UGGT (UDP-glucose: glycoprotein glucosyltransferase). Our results indicate that, similar to UGGT, CRT discriminates the proximal region at the N-glycosylation site, suggesting a similar mechanism mediating the recognition of aglycone moieties in the ER glycoprotein quality control system. - Highlights: • Glc1Man9GlcNAc2 (G1M9) ligands with different aglycones were chemically prepared. • Calreticulin (CRT) discriminates the aglycone of Glc1Man9GlcNAc2 (G1M9) ligand. • CRT binds with G1M9 ligands in a similar manner to folding sensor enzyme.
60 APPLIED LIFE SCIENCES↗
Image-based tracking system for vibration measurement of a rotating object using a laser scanning vibrometer
An image-based tracking system using laser scanning vibrometer is developed for vibration measurement of a rotating object. The proposed system unlike a conventional one can be used where the position or velocity sensor such as an encoder cannot be attached to an object. An image processing algorithm is introduced to detect a landmark and laser beam based on their colors. Then, through using feedback control system, the laser beam can track a rotating object.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
From plot to scale: ex-ante assessment of conservation agriculture in Zambia
This study combined bottom-up and top-down approaches to assess the ex-ante effects of conservation agriculture (CA)-based systems in Zambia considering both biophysical and economic factors and prevailing farm systems characteristics. For continuous maize cropping we compared a CA-based system of no-tillage with crop residue retention to a control system of conventional tillage with crop residue removal. First, we simulated yield effects that were calibrated and evaluated against multiple datasets, including on-farm agronomic trials from two seasons and six sites. Next, we extrapolated our simulations to all maize-growing areas in Zambia using gridded climate and soil datasets. Then simulated yields (in kg ha( -1 )) were combined with economic data from a nationally-representative household survey to construct economic indicators including benefit-cost ratios (based on gross benefits and variable costs both in $ ha( -1 )) that captured the implicit value of crop residues and labor demands. The field scale (per ha) indicators were scaled out using harvested areas as an expansion factor. All indicators were calculated over 3-, 10-, and 20-year simulation periods using an interpolated sequence of historical climate data. Finally, we conducted a spatial farm typology analysis to help understand the spatial variation in our field-scale indicators and provide insights into trade-offs and the suitability of CA-based systems for farmers. Average changes in yield from using CA-based systems (compared with the control) at the district scale ranged from -37% to 70% (average 33%), with a similar range of changes in benefit-cost ratios once economic factors were included, in addition to intra-district yield variability. Combining the changes in benefit cost ratios with maize harvested area resulted in an average annual change in district-scale net benefit ranging from US $ - 3.9 to US $9.9 million (with an average of US $1.1 million). The heterogeneity in biophysical and economic factors gave a ranking of provinces different according to biophysical or economic indicators, reinforcing the importance of coupling biophysical and economic approaches. The spatial farm typology analysis highlighted the specific contexts of farmers relevant to the suitability of CA, such as their mineral fertilizer applications rates, ownership of livestock, and prevailing soil texture and rainfall.
54 ENVIRONMENTAL SCIENCES↗
A study of improved MHR 50/100 toward a higher level of inherent safety
A new concept of the Mitsubishi small-sized High temperature gas-cooled modular Reactors (MHR-50/100) had been developed and published in papers. The study results of the first design concept show that the MHR-50/100 can achieve the inherent safety level set as a design target in case of water ingress during steam generator tube rupture accident. And more specifically, the reactor was shown to remain stable during long-term station black out (SBO) with protection of only passive devices during a depressurization accident and with additional motion of steam dump system during a water ingress accident. Recently greater requirements for safety of future nuclear plants including the MHR-50/100 have been expected. This study has thus made a key design improvement for the MHR-50/100 in order to secure the inherent safety aspect without reliance on active steam dump system in case of a water ingress accident. The innovative technologies listed below have been created and investigated to achieve the improved MHR-50/100 design; (1) Design improvement of steam generator, (2) Heat balance optimization of steam cycle, (3) Control system design of differential pressure between primary helium gas and water/steam, (4) Study on operation procedure during a water ingress accident. (authors)
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Renovation of Thermal Vacuum Chambers at Idaho National Laboratory (INL) for Testing of Radioisotope Power Systems (RPS)
The Radioisotope Power Systems (RPS) program at Idaho National Laboratory (INL) fuels and performs environmental testing of RPS in support of National Aeronautics and Space Administration (NASA) missions. Recently the programs’ thermal vacuum chambers, housed within INL’s Space and Security Power Systems Facility (SSPSF), underwent successful renovations to improve functional capabilities and system control in support of customer missions. Thermal vacuum system renovations focused primarily on three core functions. The first focus area was integration of semi-automated Programmable Logic Controllers (PLC) to enhance operational feedback and process control. This included the use of numerically controlled vacuum valves and integration of real time feedback from process pressure transducers. Improvements to the system high vacuum pumping technology was the second priority focus. Legacy diffusion pumps were replaced with turbo-molecular and cryogenic pumps to help mitigate the possibility of back streaming diffusion pump oil onto the surface of the test article or radiative cooling surfaces located within the chambers. The third and final core function involved meeting emergent customer thermal requirements. This led to retro-fitting one of the vacuum chambers with a cryogenically cooled Thermal Conditioning Unit (TCU) and thermal shrouds. The TCU utilizes gaseous nitrogen to heat or cool a cylindrical shroud to maintain a set temperature with a programmable range of -I85 °C to I00 °C. With the successful completion of RPS acceptance testing, the newly renovated thermal vacuum chamber systems are operational and better equipped to support testing of Radioisotope Power Systems for space exploration missions.
42 ENGINEERING↗
Renovation of Thermal Vacuum Chambers at Idaho National Laboratory for Testing of Radioisotope Power Systems
The Radioisotope Power Systems (RPS) program at Idaho National Laboratory (INL) fuels and performs environmental testing of RPS in support of National Aeronautics and Space Administration (NASA) missions. Recently the programs’ thermal vacuum chambers, housed within INL’s Space and Security Power Systems Facility (SSPSF), underwent successful renovations to improve functional capabilities and system control in support of customer missions. Thermal vacuum system renovations focused primarily on three core functions. The first focus area was integration of semi-automated Programmable Logic Controllers (PLC) to enhance operational feedback and process control. This included the use of numerically controlled vacuum valves and integration of real time feedback from process pressure transducers. Improvements to the system high vacuum pumping technology was the second priority focus. Legacy diffusion pumps were replaced with turbo-molecular and cryogenic pumps to help mitigate the possibility of back streaming diffusion pump oil onto the surface of the test article or radiative cooling surfaces located within the chambers. The third and final core function involved meeting emergent customer thermal requirements. This led to retro-fitting one of the vacuum chambers with a cryogenically cooled Thermal Conditioning Unit (TCU) and thermal shrouds. The TCU utilizes gaseous nitrogen to heat or cool a cylindrical shroud to maintain a set temperature with a programmable range of -I85 °C to I00 °C. With the successful completion of RPS acceptance testing, the newly renovated thermal vacuum chamber systems are operational and better equipped to support testing of Radioisotope Power Systems for space exploration missions.
42 ENGINEERING↗
Renovation of Thermal Vacuum Chambers at Idaho National Laboratory (INL) for Testing of Radioisotope Power Systems (RPS)
The Radioisotope Power Systems (RPS) program at Idaho National Laboratory (INL) fuels and performs environmental testing of RPS in support of National Aeronautics and Space Administration (NASA) missions. Recently the programs’ thermal vacuum chambers, housed within INL’s Space and Security Power Systems Facility (SSPSF), underwent successful renovations to improve functional capabilities and system control in support of customer missions. Thermal vacuum system renovations focused primarily on three core functions. The first focus area was integration of semi-automated Programmable Logic Controllers (PLC) to enhance operational feedback and process control. This included the use of numerically controlled vacuum valves and integration of real time feedback from process pressure transducers. Improvements to the system high vacuum pumping technology was the second priority focus. Legacy diffusion pumps were replaced with turbo-molecular and cryogenic pumps to help mitigate the possibility of back streaming diffusion pump oil onto the surface of the test article or radiative cooling surfaces located within the chambers. The third and final core function involved meeting emergent customer thermal requirements. This led to retro-fitting one of the vacuum chambers with a cryogenically cooled Thermal Conditioning Unit (TCU) and thermal shrouds. The TCU utilizes gaseous nitrogen to heat or cool a cylindrical shroud to maintain a set temperature with a programmable range of -I85 °C to I00 °C. With the successful completion of RPS acceptance testing, the newly renovated thermal vacuum chamber systems are operational and better equipped to support testing of Radioisotope Power Systems for space exploration missions.
42 ENGINEERING↗
Design and verification of distributed logic controllers with application of Petri nets
The paper deals with the designing and verification of distributed logic controllers. The control system is initially modelled with Petri nets and formally verified against structural and behavioral properties with the application of the temporal logic and model checking technique. After that it is decomposed into separate sequential automata that are working concurrently. Each of them is re-verified and if the validation is successful, the system can be finally implemented.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Beam characteristics of energy-matched flattening filter free beams
Purpose: Flattening filter free (FFF) linear accelerators can increase treatment efficiency and plan quality. There are multiple methods of defining a FFF beam. The Elekta control system supports tuning of the delivered FFF beam energy to enable matching of the percentage depth-dose (PDD) of the flattened beam at 10 cm depth. This is compared to FFF beams where the linac control parameters are identical to those for the flattened beam. All beams were delivered on an Elekta Synergy accelerator with an Agility multi-leaf collimator installed and compared to the standard, flattened beam. The aim of this study is to compare “matched” FFF beams to both “unmatched” FFF beams and flattened beams to determine the benefits of matching beams. Methods: For the three modes of operation 6 MV flattened, 6 MV matched FFF, 6 MV unmatched FFF, 10 MV flattened, 10 MV matched FFF, and 10 MV unmatched FFF beam profiles were obtained using a plotting tank and were measured in steps of 0.1 mm in the penumbral region. Beam penumbra was defined as the distance between the 80% and 20% of the normalized dose when the inflection points of the unflattened and flattened profiles were normalized with the central axis dose of the flattened field set as 100%. PDD data was obtained at field sizes ranging from 3 cm × 3 cm to 40 cm × 40 cm. Radiation protection measurements were additionally performed to determine the head leakage and environmental monitoring through the maze and primary barriers. Results: No significant change is made to the beam penumbra for FFF beams with and without PDD matching, the maximum change in penumbra for a 10 cm × 10 cm field was within the experimental error of the study. The changes in the profile shape with increasing field size are most significant for the matched FFF beam, and both FFF beams showed less profile shape variation with increasing depth when compared to flattened beams, due to consistency in beam energy spectra across the radiation field. The PDDs of the FFF beams showed less variation with field size, the d{sub max} value was deeper for the matched FFF beam than the FFF beam and deeper than the flattened beam for field sizes greater than 5 cm × 5 cm. The head leakage when using the machine in FFF mode is less than half that for a flattened beam, but comparable for both FFF modes. The radiation protection dose-rate measurements show an increase of instantaneous dose-rates when operating the machines in FFF mode but that increase is less than the ratio of MU/min produced by the machine. Conclusions: The matching of a FFF beam to a flattened beam at a depth of 10 cm in water by increasing the FFF beam energy does not reduce any of the reported benefits of FFF beams. Conversely, there are a number of potential benefits resulting from matching the FFF beam; the depth of maximum dose is deeper, the out of field dose is potentially reduced, and the beam quality and penetration more closely resembles the flattened beams currently used in clinical practice, making dose distributions in water more alike. Highlighted in this work is the fact that some conventional specifications and methods for measurement of beam parameters such as penumbra are not relevant and further work is required to address this situation with respect to “matched” FFF beams and to determine methods of measurement that are not reliant on an associated flattened beam.
43 PARTICLE ACCELERATORS↗
Design and performance of an in-vacuum, magnetic field mapping system for the Muon g-2 experiment
The E989 Muon g-2 experiment at Fermilab aims to measure the anomalous magnetic moment, a$_\mu$, of the muon with a precision of 140 parts-per-billion. This requires a precise measurement of both the anomalous spin precession frequency, $\omega_a$, and the average magnetic field in terms of the equivalent, free proton Larmor frequency, $\omega_p$. The measurement of $\omega_p$ with a total systematic uncertainty of 70 parts-per-billion involves a combination of various NMR probes. There are 378 probes in fixed locations constantly monitoring field drifts. A water-based probe provides the calibration in terms of $\omega_p$. A crucial element for the multi-step measurement of $\omega_p$ is the regular mapping of the magnetic field over the muon storage region. The former E821 experiment at Brookhaven employed an in-vacuum field mapping system equipped with 17 NMR probes, which was developed by the University of Heidelberg. We have refurbished and upgraded this system with new probes and electronics. The upgrades include a new communication scheme incorporating time-division multiplexing to separate the important NMR reference clock from the data communication. The addition digitization of the NMR signals replaced the hardware-implemented zero-crossing counting of the E821 system. The digitized signals offer new capabilities in the NMR frequency analysis and its related systematic uncertainties. While the mechanical systems that move the field mapper around the ring have been mostly refurbished, the motion control system was completely replaced with a custom-built electronics centered around a commercial Galil motion controller. Both the field mapping NMR system and its motion control were successfully commissioned at Fermilab and have been in reliable operation during the first data taking periods. This article provides details of the upgrades of the field mapper and its performance.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Light Water Reactor Sustainability Program (2015 Accomplishments Report)
This report covers selected highlights from the four research pathways in the LWRS Program: Materials Aging and Degradation; Risk-Informed Safety Margin Characterization; Advanced Instrumentation, Information, and Control Systems Technologies; and Reactor Safety Technologies, as well as a look-ahead at planned activities for 2016.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗