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DOE OSTI2025

Risk-informed Graded Approach for Reliability and Performance Assessment of Machine Learning and Artificial Intelligence for Advanced Condition Monitoring Techniques

With the shift away from time-based maintenance and toward condition-based maintenance, and to reduce overall maintenance costs, there has been an upsurge in the usage and development of advanced condition monitoring (ACM) techniques for real-time monitoring of nuclear power plant (NPP) components. ACM is particularly useful in the development of digital twins, which are designed to predict the failure or degradation of plant components. Successful implementation of ACM requires an assessment to inform the development of a risk-informed approach to evaluate the use of ACM to meet Nuclear Regulatory Committee (NRC) regulations for in-service testing (IST) programs. This includes the monitoring and diagnostics of reactor components and systems in current, new, and advanced reactors. A key component in ACM is the usage of machine learning (ML) and artificial intelligence (AI) algorithms that can employ real-time data from instrumentation and sensors to detect and predict reactor component degradations. Such predictive capabilities enable early detection of component degradation so as to help plant personnel plan and execute necessary maintenance. For successful implementation of ML/AI in ACM such that regulatory requirements are met, a risk-informed graded approach is needed to assess the reliability and performance of ML/AI for ACM. The American Society for Mechanical Engineers (ASME) developed their Operations and Maintenance (O&M) Code to provide guidance on safe, reliable O&M of NPPs. The IST section of the O&M Code specifically establishes requirements for IST and examination to gauge operational readiness of components in water-cooled NPPs. This paper presents a state-of-the-art review of how reliability and risk assessment can be integrated with ACM to assess component performance by non-nuclear industries. This is followed by different methodologies and approaches for conducting performance and reliability assessments so as to meet IST requirements for NPP components.

97 - MATHEMATICS AND COMPUTING↗

NASA NTRSDate not supplied

Comparative Analysis of Thermal Conversion Technologies for Deep Space Missions

Radioisotope power systems (RPS) utilizing Plutonium-238 as a heat source for thermal-to-electric energy conversion have been used as a reliable power source for NASA’s deep space missions for sixty years. Recent innovations and improvements to thermal energy technologies show potential increases to radioisotope system efficiencies from current measurements of ~5-7% to efficiencies upwards of 20%. This report surveys and ranks recent, innovative thermal-to-electric energy conversion research technologies. Technologies being developed at universities and industry are compared with respect to thermal conversion method and relevant key performance parameters. Key performance parameters are identified as system specific power per kg, efficiency, power output, technology readiness level, and system mass. Analytical Hierarchy Process (AHP) was utilized to create weighted values for each evaluation criterion. The AHP tables combined with decision matrices create table scores for past, present, and potential future systems. The table score was combined with a conversion method score in an adjustable system to add value to flight-proven or well-tested thermal conversion technologies such as thermoelectrics. While the three highest-ranking systems reviewed are currently being developed by NASA’s RPS Program, the additional highest-ranking systems not under-development by RPS could warrant further research.

Radioisotope Power System↗

DOE OSTI2025

Risk-informed Graded Approach for Reliability and Performance Assessment for Advanced Condition Monitoring Techniques

99 - GENERAL AND MISCELLANEOUS↗

DOE OSTI2023

Bat Smart Curtailment: Efficacy and Operational Testing

Curtailment, or blanket curtailment, is a leading method to mitigate the impacts to bats from operating wind turbines. Although this strategy results in considerable decreases in bat fatalities, it also results in decreased energy production. In 2019, Natural Power was awarded funding by the Department of Energy to assess the readiness of the informed smart curtailment technology, EchoSense (formerly referred to as Detection and Active Response Curtailment, [DARC]). The research undertaken by this project expands the understanding of alternative methods, known as smart curtailment, to maintain a reduction in bat fatalities while simultaneously recovering lost energy associated with blanket curtailment. The overall project was composed of three major tasks; Task 1 was focused on cybersecurity compliance of the EchoSense system in accordance with the North American Electric Reliability Corporation Critical Infrastructure Protection (“NERC CIP”) standards, Task 2 assessed the mechanical loads exerted on turbines when operating under a smart curtailment regime, and Task 3 assessed the efficacy of the EchoSense system at an operational wind farm. Regarding Task 1, an external review by the National Renewable Energy Laboratory determined that the EchoSense system did not create any new cybersecurity weaknesses and was compliant with the NERC CIP standards. As a result of this process, Natural Power developed some best practices (10.1) for wind- wildlife technology developers. In conjunction with the National Renewable Energy Laboratory, the results (10.2) of the loads testing demonstrated that the periodic curtailment and release of turbines by the EchoSense system did not have any detrimental impact on the mechanical components of a wind turbine (Task 2). During the late summer to fall of 2020 and 2021, Natural Power demonstrated that the use of the EchoSense smart curtailment system resulted in no significant difference in bat fatalities compared to blanket curtailment with cut-in speeds at 6.9 m/s (2020) and 5.0 m/s (2021) while resulting in a significant difference in decreased lost energy (Task 3). This translates to an average of 41% (2020) and 56% (2021) reduction in per turbine energy loss compared to blanket curtailment. The reduction in energy loss that would have been achieved by EchoSense curtailment compared to blanket curtailment, if applied across all 69 turbines, is roughly equivalent to having an additional turbine on site. These results are notable for finding a balance between the environmental impact of wind energy and the economic feasibility in energy production associated with mitigating that impact. https://www.naturalpower.com/us/expertise/service/engineering-operations/echosense

17 WIND ENERGY↗

NASA NTRS1980

The NASA high-speed turboprop program

NASA's Advanced Turboprop Project is a three-phase effort initiated in 1978 to provide technology readiness for Mach 0.7 to 0.8 turboprop-powered aircraft; with the potential for fuel savings and DOC reductions of up to 30 and 15%, respectively, relative to current in-service aircraft. This paper reviews the status of Phase I in the areas of propeller aeroacoustics, propeller structures, turboprop installed performance, aircraft cabin environment, and turboprop engine and aircraft studies. Current plans to establish large-scale propeller characteristics and to conduct high-speed propeller flight research tests using a modified testbed aircraft are also presented.

Dugan, J. F.↗

NASA NTRS1987

Electromagnetic emission experiences using electric propulsion systems: A survey

As electric propulsion systems become ready to integrate with spacecraft systems, the impact of propulsion system radiated emissions are of significant interest. Radiated emissions from electromagnetic, electrostatic, and electrothermal systems have been characterized and results synopsized from the literature describing 21 space flight programs. Electromagnetic radiated emission results from ground tests and flight experiences are presented with particular attention paid to the performance of spacecraft subsystems and payloads during thruster operations. The impacts to transmission of radio frequency signals through plasma plumes are also reviewed.

Sovey, James S.↗

NASA NTRS1987

Electromagnetic emission experiences using electric propulsion systems - A survey

Sovey, James S.↗

NASA NTRS2000

Development of a PPT for the EO-1 Spacecraft

A Pulsed Plasma Thruster (PPT) has been developed for use in a technology demonstration flight experiment on the Earth Observing 1 (EO-1) New Millennium Program mission. The thruster replaces the spacecraft pitch axis momentum wheel for control and momentum management during an experiment of a minimum three-day duration. The EO-1 PPT configuration is a combination of new technology and design heritage from similar systems flown in the 1970's and 1980's. Acceptance testing of the protoflight unit has validated readiness for flight, and integration with the spacecraft, including initial combined testing, has been completed. The thruster provides a range of capability from 90 microN-sec impulse bit at 650 sec specific impulse for 12 W input power, through 860 microN-sec impulse bit at 1400 see specific impulse for 70 W input power. Development of this thruster reinitiates technology research and development and re-establishes an industry base for production of flight hardware. This paper reviews the EO-1 PPT development, including technology selection, design and fabrication, acceptance testing, and initial spacecraft integration and test.

Benson, Scott W.↗

NASA NTRSDate not supplied

A Technology Maturation Plan for the Development of Nuclear Electric Propulsion

Over the last two years NASA’s Space Nuclear Propulsion (SNP) Project formulated a Technology Maturation Plan (TMP) for development of the sub-systems needed for a MW-class Nuclear Electric Propulsion (NEP) system which, combined with a high thrust chemical propulsion stage, would be suitable for human missions to Mars. Two recent assessments, independently conducted by the National Academies for Science, Engineering, and Medicine and the NASA Engineering & Safety Center, concluded that the technologies required for a high-power NEP system are immature and the attendant risks insufficiently quantified to justify initiating a flight project. For NEP to be available as a viable option to meet flight opportunities in the late 2030s / 2040s time frame, development of the key sub-systems must begin now. SNP has subdivided the NEP system into five Critical Technology Elements (CTE): the nuclear reactor, power conversion, power management and distribution, electric propulsion sub-system, and the primary heat rejection system. Development plans for each of these CTEs have been drafted which will serve as the template for a focused milestone-driven research and development campaign intended to advance each CTE to Technology Readiness Level (TRL) 5. This will be accomplished by building and testing hardware at relevant power levels (~ 1 MW) and for relevant durations (2,500 hours, ~10% of the required operational lifetime) and conducting numerical modeling of the CTEs anchored by the accumulated test data to predict system performance and reliability. Concurrent with this work, high-level coupled system/mission modeling will be carried out to refine the key performance parameters that the various CTEs must achieve. Non-advocate reviews will be held at milestone points to assess progress and inform down-select decisions. The strategy for formulating the TMP was described previously; this paper describes ongoing progress on the drafting and baselining of the plan, including key specific details.

Space Nuclear Propulsion↗

NASA NTRSDate not supplied

A Technology Maturation Plan for the Development of Nuclear Electric Propulsion

Over the last two years NASA’s Space Nuclear Propulsion (SNP) Project formulated a Technology Maturation Plan (TMP) for development of the sub-systems needed for a MW-class Nuclear Electric Propulsion (NEP) system which, combined with a high thrust chemical propulsion stage, would be suitable for human missions to Mars. Two recent assessments, independently conducted by the National Academies for Science, Engineering, and Medicine and the NASA Engineering & Safety Center, concluded that the technologies required for a high-power NEP system are immature and the attendant risks insufficiently quantified to justify initiating a flight project. For NEP to be available as a viable option to meet flight opportunities in the late 2030s / 2040s time frame, development of the key sub-systems must begin now. SNP has subdivided the NEP system into five Critical Technology Elements (CTE): the nuclear reactor, power conversion, power management and distribution, electric propulsion sub-system, and the primary heat rejection system. Development plans for each of these CTEs have been drafted which will serve as the template for a focused milestone-driven research and development campaign intended to advance each CTE to Technology Readiness Level (TRL) 5. This will be accomplished by building and testing hardware at relevant power levels (~ 1 MW) and for relevant durations (2,500 hours, ~10% of the required operational lifetime) and conducting numerical modeling of the CTEs anchored by the accumulated test data to predict system performance and reliability. Concurrent with this work, high-level coupled system/mission modeling will be carried out to refine the key performance parameters that the various CTEs must achieve. Non-advocate reviews will be held at milestone points to assess progress and inform down-select decisions. The strategy for formulating the TMP was described previously*; this paper describes ongoing progress on the drafting and baselining of the plan, including key specific details. * “Strategy for Developing Technologies for Megawatt-class Nuclear Electric Propulsion Systems”, K.A. Polzin, et. al., International Electric Propulsion Conference IEPC 2022, IEPC-2022-155

Nuclear Electric Propulsion↗

DOE OSTI2022

Development of High-Temperature Emissivity Measurement Capabilities for Molten Salts at PNNL

In this study, an emissivity measurement system for a liquid molten salt was developed on the bases on the Stefan Boltzmann Law. A prototype device operating in ambient atmosphere was constructed an initial result compared well with available literature. The diffuse emissivity of NaCl-KCl system (NaCl, 51mol% NaCl – 49mol% KCl and KCl) was measured from 550 to 850 °C at a wavelength of 1.3 µm. The system appears to be relatively invariant with composition but a clear trend of decreasing emissivity values from ~0.9 at 550 °C to 0.75 at 850 °C was observed. A schematic for an enclosed system for inert atmosphere and actinide salts was drafted. Several of the components for fabrication of this device, improved laser system, furnace, nickel for capsule construction, have been purchased and are ready for assembly. The new laser system will have an improved measurement range of 275-1000 °C. The clam shell furnace has a maximum temperature of 1200 °C and will support the hermetically sealed inert encapsulation vessels. Nickel plate and tubing will create a relatively corrosion resistance capsule for testing that can withstand temperature up to 1000 °C. Emissivity measurements are important for a larger effort to understand radiative heat transfer within molten salts at elevated temperatures (600-1000 °C). Literature review of optical salt properties and radiative heat transfer models indicated that systems within elevated temperature regimes could see upwards of 20% or more of their total heat transferred through photonic mechanisms. Ultimately, future work will measure the total thermal conductivity and break down the molecular and radiative portions. Thermal conductivity, along with other thermal properties of molten salts, both coolant and fuel, are fundamental to modeling and simulations that support MSR design. The results presented here and ongoing work at PNNL will be useful in selecting optimal salt compositions, designing reactor systems, and optimizing heat transfer within a MSR power plant.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

NASA NTRS2019

Technology Development Roadmap for Habitable-Zone Exoplanet Observatory (HabEx) Baseline 4-M Primary Mirror

The Habitable Exoplanet Observatory (HabEx) is one of four mission concepts under study for the 2020 Astrophysics Decadal Survey. Its goal is to directly image and spectroscopically characterize planetary systems in the habitable zone around nearby sun-like stars. Additionally, HabEx will perform a broad range of general astrophysics science enabled by 115 to 2500 nm spectral range and 3 x 3 arc-minute FOV. Critical to achieving the HabEx science goals is a large, ultra-stable UV/Optical/Near-IR (UVOIR) telescope. The baseline HabEx telescope is 4-meter off-axis unobscured, diffraction limited at 400 nm with wavefront stability on the order of a few 10s of picometers. The technology readiness level (TRL) to manufacture and test the HabEx baseline primary mirror is assessed to be at TRL-6 for all but two TRL-4 technologies: 1) non-destructive process to quantify CTE homogeneity of a 4-m mirror substrate with a spatial sampling of at least 100 x 100 to better than +/- 1 ppb/K; and, 2) process to quantify self-weight gravity deflection to better than 4-nm rms over a 100 x 100 spatial sampling. This paper reviews the technology needs to manufacture the HabEx primary mirror, assesses their TRL and proposes a roadmap to mature the two remaining technologies to TRL-6.

Space Telescope Technology↗

NASA NTRS1981

A Module Experimental Process System Development Unit (MEPSDU)

The purpose of this program is to demonstrate the technical readiness of a cost effective process sequence that has the potential for the production of flat plate photovoltaic modules which met the price goal in 1986 of $.70 or less per watt peak. Program efforts included: preliminary design review, preliminary cell fabrication using the proposed process sequence, verification of sandblasting back cleanup, study of resist parameters, evaluation of pull strength of the proposed metallization, measurement of contact resistance of Electroless Ni contacts, optimization of process parameter, design of the MEPSDU module, identification and testing of insulator tapes, development of a lamination process sequence, identification, discussions, demonstrations and visits with candidate equipment vendors, evaluation of proposals for tabbing and stringing machine.

Source record↗

NASA NTRS2018

The SPACE Computer Code for Analyzing the International Space Station Electrical Power System: Past, Present, and Future

The System Power Analysis for Capability Evaluation (SPACE) computer code was initially developed by NASA in 1988 to assess the Space Station Freedom electric power system and later adapted to support contractor electrical power system capability analyses for the International Space Station (ISS). Over time, the code has supported many efforts such as ISS redesign activities in the early 1990s, assessment of time-phased loads against power system operating limits for future ISS assembly flights (including Certification of Flight Readiness reviews by the ISS program office), and determining the optimum solar array gimbal positions while respecting keep-out zones which minimize both solar array contamination and structural loads. The code has been validated by comparisons with ISS on-orbit data in multiple validation episodes. Recent updates to the code include the incorporation of a Lithium-Ion battery model in addition to the Nickel Hydrogen battery model and modifications to the solar array degradation model to better match on-orbit test results. SPACE has also been extended beyond the ISS to include modeling of the Orion Multi-Purpose Crew Vehicle electrical power system (SPACE-MPCV) and Mars Surface Electrical Power Systems (MSEPS). Portions of SPACE were integrated with a trajectory code to form a Solar Electric Propulsion Simulation (SEPSim), which can be used for analyzing solar electric propulsion missions. In addition, SPACE methods and subroutines have been adapted to a multitude of other projects. This paper summarizes the initial code development and subsequent code utilization in the context of the overall ISS program development and on-orbit operations. Recent updates and results from the code are discussed, including preliminary analyses for the Orion power system.

Electrical Power System↗

NASA NTRS2007

Human Factors in the Design of the Crew Exploration Vehicle (CEV)

NASA s Space Exploration vision for humans to venture to the moon and beyond provides interesting human factors opportunities and challenges. The Human Engineering group at NASA has been involved in the initial phases of development of the Crew Exploration Vehicle (CEV), Orion. Getting involved at the ground level, Human Factors engineers are beginning to influence design; this involvement is expected to continue throughout the development lifecycle. The information presented here describes what has been done to date, what is currently going on, and what is expected in the future. During Phase 1, prior to the contract award to Lockheed Martin, the Human Engineering group was involved in generating requirements, conducting preliminary task analyses based on interviews with subject matter experts in all vehicle systems areas, and developing preliminary concepts of operations based on the task analysis results. In addition, some early evaluations to look at CEV net habitable volume were also conducted. The program is currently in Phase 2, which is broken down into design cycles, including System Readiness Review, Preliminary Design Review, and Critical Design Review. Currently, there are ongoing Human Engineering Technical Interchange Meetings being held with both NASA and Lockheed Martin in order to establish processes, desired products, and schedules. Multiple design trades and quick-look evaluations (e.g. display device layout and external window size) are also in progress. Future Human Engineering activities include requirement verification assessments and crew/stakeholder evaluations of increasing fidelity. During actual flights of the CEV, the Human Engineering group is expected to be involved in in-situ testing and lessons learned reporting, in order to benefit human space flight beyond the initial CEV program.

Whitmore, Mihriban↗

NASA NTRS2005

Multiple Payload Ejector for Education, Science and Technology Experiments

The education research community no longer has a means of being manifested on Space Shuttle flights, and small orbital payload carriers must be flown as secondary payloads on ELV flights, as their launch schedule, secondary payload volume and mass permits. This has resulted in a backlog of small payloads, schedule and cost problems, and an inability for the small payloads community to achieve routine, low-cost access to orbit. This paper will discuss Goddard's Wallops Flight Facility funded effort to leverage its core competencies in small payloads, sounding rockets, balloons and range services to develop a low cost, multiple payload ejector (MPE) carrier for orbital experiments. The goal of the MPE is to provide a low-cost carrier intended primarily for educational flight research experiments. MPE can also be used by academia and industry for science, technology development and Exploration experiments. The MPE carrier will take advantage of the DARPAI NASA partnership to perform flight testing of DARPA s Falcon small, demonstration launch vehicle. The Falcon is similar to MPE fiom the standpoint of focusing on a low-cost, responsive system. Therefore, MPE and Falcon complement each other for the desired long-term goal of providing the small payloads community with a low-cost ride to orbit. The readiness dates of Falcon and MPE are complementary, also. MPE is being developed and readied for flight within 18 months by a small design team. Currently, MPE is preparing for Critical Design Review in fall 2005, payloads are being manifested on the first mission, and the carrier will be ready for flight on the first Falcon demonstration flight in summer, 2006. The MPE and attached experiments can weigh up to 900 lb. to be compatible with Falcon demonstration vehicle lift capabilities fiom Wallops, and will be delivered to the Falcon demonstration orbit - 100 nautical mile circular altitude.

Lechworth, Gary↗

NASA NTRS1993

COMET: First mission progress

The COMmercial Experiment Transporter (COMET) is a set of hardware and related infrastructure used to support orbital experiments of the Commerical Centers for the Development of Space (CCDS's) and their industrial partners. During the three years since the program started, contracts have been signed, design reviews conducted on all components, experiments selected for the first mission, all hardware has been manufactured, the first phase of integrated testing of the satellite, the experiments, and the Launch Facility have all been completed. The program experienced several delays in 1993. A component failure in the Service Module during preparation for environmental testing in January resulted in an eight-week delay for the Service Module part of the FreeFlyer. Discovery of large overruns of the mass budget required a major revision of the mission profile for COMET 1. In the spring of 1993, Space Industries Incorporated (SII) and Westinghouse stopped work because of a lack of funds. EER continued to work toward completion of their launch systems. SII and Westinghouse resumed work in September 1993. Since resumption of work, a technical review of all systems to ascertain their state of readiness has been completed. No major problems were discovered. All systems are proceeding toward a launch date in the first quarter of 1994.

Pawlick, Joseph F., Jr.↗

NASA NTRS2015

Achieving TASAR Operational Readiness

NASA has been developing and testing the Traffic Aware Strategic Aircrew Requests (TASAR) concept for aircraft operations featuring a NASA-developed cockpit automation tool, the Traffic Aware Planner (TAP), which computes traffic/hazard-compatible route changes to improve flight efficiency. The TAP technology is anticipated to save fuel and flight time and thereby provide immediate and pervasive benefits to the aircraft operator, as well as improving flight schedule compliance, passenger comfort, and pilot and controller workload. Previous work has indicated the potential for significant benefits for TASAR-equipped aircraft, and a flight trial of the TAP software application in the National Airspace System has demonstrated its technical viability. This paper reviews previous and ongoing activities to prepare TASAR for operational use.

Wing, David J.↗