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At least 91 records · Page 5

Reactivity Studies of Inconel 625 with Sodium, and Lunar Regolith Stimulant

In the event of the need for nuclear power in exploration, high flux heat pipes will be needed for heat transfer from space nuclear reactors to various energy conversion devices, and to safely dissipate excess heat. Successful habitation will necessitate continuous operation of alkali metal filled heat pipes for 10 or-more years in a hostile environment with little maintenance. They must be chemical and creep resistant in the high vacuum of space (lunar), and they must operate reliably in low gravity conditions with intermittent high radiation fluxes. One candidate material for the heat pipe shell, namely Inconel 625, has been tested to determine its compatibility with liquid sodium. Any reactivity could manifest itself as a problem over the long time periods anticipated. In addition, possible reactions with the lunar regolith will take place, as will evaporation of selected elements at the external surfaces of the heat pipes, and so there is a need for extensive long-term testing under simulated lunar conditions.

Gillies, Donald↗

Comparison of evolving photovoltaic and nuclear power systems for earth orbital applications

Photovoltaic and fission reactor orbital power systems are compared in terms of the end-to-end system power-to-mass ratios. Three PV systems are examined, i.e., a solid substrate with a cell array and a NiCd battery, a modified SEP array and an NiH2 battery, and a 62-micron Si cell array and a fuel cell. All arrays were modeled to be 13.5% efficient and to produce 25 kW dc. The SP-100 reactor consists of the heat source, radiation shield, heat pipes to transfer thermal energy from the reactor to thermoelectric elements, and a waste heat radiator. Consideration is given to system applications in orbits ranging from LEO to GEO, and to mission durations of 1, 5, and 10 yr. PV systems are concluded to be flight-proven, useful out of radiation belts, and best for low to moderate power levels. Limitations exist for operations where atmospheric drag may become a factor and due to the size of a large PV power supply. Space nuclear reactors will continue under development and uses at high power levels and in low altitude orbits are foreseen.

Rockey, D. E.↗

High Temperature Heat Rejection System for Large Heat Loads; Architecture and Trade Study Results

To investigate space nuclear reactor technologies, NASA has awarded several contracts under Project Prometheus, the Nuclear Systems Program. The effort described in this paper was performed under one of those contracts (the Brayton NRA) . Like all power conversion systems, nuclear power conversion systems operate at efficiencies less than 100% resulting in the need to reject waste heat to space. Several different HRSs (Heat Rejection Systems) potential designs have been identified for rejecting NEP (Nuclear Electric Power) waste heat and several of them for a CBC (Closed Brayton Cycle) power conversion system are described herein and the results of their initial analyses presented. The analyses presented were performed as part of an initial trade study to recommend a promising HRS for advancement of its TRL.

Nilitkin, Michael N.↗

Thermionic technology infrastructure for space power

An assessment is made of the potential effectiveness, designs, and technological difficulties involved in the construction of space nuclear reactors coupled to thermionic energy converters (TEC). The TECs can be positioned either inside or outside of the reactor core. The out-of-core design lowers the reactor shielding requirements, as well as removing the need for mechanically pumped coolant for the reactor. R&D is still needed for the heat pipes for the reactor and the collectors, electrical insulation, and to reduce the potential losses in the interelectrode space. A cylindrical converter for the out-of-core configuration consists of a tungsten emitter heated by a tungsten-lithium heat pipe. The collector is a layer of tungsten oxide deposited on a Nb-1%Zr alloy, and has been tested at emitter temperatures of 1300-1850 K and a collector temperature range of 700-850 K. A design of a superheated thermionic converter is described, noting that a prototype has been operated at 1730 K for 12,000 hr.

Huffman, F.↗

Safety status of space radioisotope and reactor power sources

The current overall safety criterion for both radioisotope and reactor power sources is containment or immobilization in the case of a reentry accident. In addition, reactors are designed to remain subcritical under conditions of land impact or water immersion. A very extensive safety test and analysis program was completed on the radioisotope thermoelectric generators (RTGs) in use on the Galileo spacecraft and planned for use on the Ulysses spacecraft. The results of this work show that the RTGs will pose little or no risk for any credible accident. The SP-100 space nuclear reactor program has begun addressing its safety criteria, and the design is planned to be such as to ensure meeting the various safety criteria. Preliminary mission risk analyses on SP-100 show the expected value population dose from postulated accidents on the reference mission to be very small. It is concluded that the current US nuclear power sources are the safest flown.

Bennett, Gary L.↗

NASA Tech Briefs, September 2013

Topics include: ISS Ammonia Leak Detection Through X-Ray Fluorescence; A System for Measuring the Sway of the Vehicle Assembly Building; Fast, High-Precision Readout Circuit for Detector Arrays; Victim Simulator for Victim Detection Radar; Hydrometeor Size Distribution Measurements by Imaging the Attenuation of a Laser Spot; Quasi-Linear Circuit; High-Speed, High-Resolution Time-to-Digital Conversion; Li-Ion Battery and Supercapacitor Hybrid Design for Long Extravehicular Activities; Ultrasonic Low-Friction Containment Plate for Thermal and Ultrasonic Stir Weld Processes; High-Powered, Ultrasonically Assisted Thermal Stir Welding; Next-Generation MKIII Lightweight HUT/Hatch Assembly; Centrifugal Sieve for Gravity-Level-Independent Size; Segregation of Granular Materials; Ion Exchange Technology Development in Support of the Urine Processor Assembly; Nickel-Graphite Composite Compliant Interface and/or Hot Shoe Material; UltraSail CubeSat Solar Sail Flight Experiment; Mechanism for Deploying a Long, Thin-Film Antenna From a Rover; Counterflow Regolith Heat Exchanger; Acquisition and Retaining Granular Samples via a Rotating Coring Bit; Very-Low-Cost, Rugged Vacuum System; Medicine Delivery Device With Integrated Sterilization and Detection; FRET-Aptamer Assays for Bone Marker Assessment, C-Telopeptide, Creatinine, and Vitamin D; Multimode Directional Coupler for Utilization of Harmonic Frequencies from TWTAs; Dual-Polarization, Multi-Frequency Antenna Array for use with Hurricane Imaging Radiometer; Complementary Barrier Infrared Detector (CBIRD) Contact Methods; Autonomous Control of Space Nuclear Reactors; High-Power, High-Speed Electro-Optic Pockels Cell Modulator; Covariance Analysis Tool (G-CAT) for Computing Ascent, Descent, and Landing Errors; Enigma Version 12; Micrometeoroid and Orbital Debris (MMOD) Shield Ballistic Limit Analysis Program; Spitzer Telemetry Processing System; Planetary Protection Bioburden Analysis Program; Wing Leading Edge RCC Rapid Response Damage Prediction Tool (IMPACT2); ISSM: Ice Sheet System Model; Automated Loads Analysis System (ATLAS); Integrated Main Propulsion System Performance Reconstruction Process/Models. Phoenix Telemetry Processor; Contact Graph Routing Enhancements Developed in ION for DTN; GFEChutes Lo-Fi; Advanced Strategic and Tactical Relay Request Management for the Mars Relay Operations Service; Software for Generating Troposphere Corrections for InSAR Using GPS and Weather Model Data; Ionospheric Specifications for SAR Interferometry (ISSI); Implementation of a Wavefront-Sensing Algorithm; Sally Ride EarthKAM - Automated Image Geo-Referencing Using Google Earth Web Plug-In; Trade Space Specification Tool (TSST) for Rapid Mission Architecture (Version 1.2); Acoustic Emission Analysis Applet (AEAA) Software; Memory-Efficient Onboard Rock Segmentation; Advanced Multimission Operations System (ATMO); Robot Sequencing and Visualization Program (RSVP); Automating Hyperspectral Data for Rapid Response in Volcanic Emergencies; Raster-Based Approach to Solar Pressure Modeling; Space Images for NASA JPL Android Version; Kinect Engineering with Learning (KEWL); Spacecraft 3D Augmented Reality Mobile App; MPST Software: grl_pef_check; Real-Time Multimission Event Notification System for Mars Relay; SIM_EXPLORE: Software for Directed Exploration of Complex Systems; Mobile Timekeeping Application Built on Reverse-Engineered JPL Infrastructure; Advanced Query and Data Mining Capabilities for MaROS; Jettison Engineering Trajectory Tool; MPST Software: grl_suppdoc; PredGuid+A: Orion Entry Guidance Modified for Aerocapture; Planning Coverage Campaigns for Mission Design and Analysis: CLASP for DESDynl; and Space Place Prime.

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Advanced and Nontraditional Concepts Working Group Report

Advanced and nontraditional concepts relating to future space power requirements were examined with special emphasis on the requirements for the space station. Key findings in the following ares are outlined: dynamic radiation concepts, space nuclear reactors, energy conversion cycles, beam power transmission, electrodynamic tethers and advanced photovoltaics.

Hertzberg, A.↗

Modeling of transient heat pipe operation

Mathematical models and associated solution procedures which can be used to design heat pipe cooled structures for use on hypersonic vehicles are being developed. The models should also have the capability to predict off-design performance for a variety of operating conditions. It is expected that the resulting models can be used to predict startup behavior of liquid metal heat pipes to be used in reentry vehicles, hypersonic aircraft, and space nuclear reactors. Work to date related to numerical solutions of governing differential equations for the outer shell and the combination capillary structure and working fluid is summarized. Finite element numerical equations using both implicit, explicit, and combination methods were examined.

Colwell, G. T.↗

Static conversion systems

Historically, all space power systems that have actually flown in space have relied on static energy conversion technology. Thus, static conversion is being considered for space nuclear power systems as well. There are four potential static conversion technologies which should be considered. These include: the alkali metal thermoelectric converter (AMTEC), the thermionic converter, the thermoelectric converter, and the thermophotovoltaic converter (TPV). These four conversion technologies will be described in brief detail along with their current status and development needs. In addition, the systems implications of using each of these conversion technologies with a space nuclear reactor power system will be evaluated and some comparisons made.

Ewell, R.↗

SP-100 Advanced Technology Program

The goal of the triagency SP-100 Program is to develop long-lived, compact, lightweight, survivable nuclear reactor space power systems for application to the power range 50 kWe to 1 MWe. The successful development of these systems should enable or significantly enhance many of the future NASA civil and commercial missions. The NASA SP-100 Advanced Technology Program strongly augments the parallel SP-100 Ground Engineering System Development program and enhances the chances for success of the overall SP-100 program. The purpose of this paper is to discuss the key technical elements of the Advanced Technology Program and the progress made in the initial year and a half of the project.

Sovie, Ronald J.↗

Small reactor power systems for manned planetary surface bases

A preliminary feasibility study of the potential application of small nuclear reactor space power systems to manned planetary surface base missions was conducted. The purpose of the study was to identify and assess the technology, performance, and safety issues associated with integration of reactor power systems with an evolutionary manned planetary surface exploration scenario. The requirements and characteristics of a variety of human-rated modular reactor power system configurations selected for a range of power levels from 25 kWe to hundreds of kilowatts is described. Trade-off analyses for reactor power systems utilizing both man-made and indigenous shielding materials are provided to examine performance, installation and operational safety feasibility issues. The results of this study have confirmed the preliminary feasibility of a wide variety of small reactor power plant configurations for growth oriented manned planetary surface exploration missions. The capability for power level growth with increasing manned presence, while maintaining safe radiation levels, was favorably assessed for nominal 25 to 100 kWe modular configurations. No feasibility limitations or technical barriers were identified and the use of both distance and indigenous planetary soil material for human rated radiation shielding were shown to be viable and attractive options.

Bloomfield, Harvey S.↗

SP-100 Advanced Technology Program

The goal of the triagency SP-100 Program is to develop long-lived, compact, lightweight, survivable nuclear reactor space power systems for application to the power range 50 kWe to 1 MWe. The successful development of these systems should enable or significantly enhance many of the future NASA civil and commercial missions. The NASA SP-100 Advanced Technology Program strongly augments the parallel SP-100 Ground Engineering System Development program and enhances the chances for success of the overall SP-100 program. The purpose of this paper is to discuss the key technical elements of the Advanced Technology Program and the progress made in the initial year and a half of the project.

Sovie, Ronald J.↗

Nuclear-electric reusable orbital transfer vehicle

To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined that utilize electric propulsion supported by the nuclear reactor's power for multiple transfers of cargo between low earth orbit (LEO) and geosynchronous earth orbit (GEO). A propulsion system employing ion thrusters and xenon propellant was selected. Propellant and thrusters are replaced after each sortie to GEO. The mass of the orbital transfer vehicle (OTV), empty and dry, is 11,000 kg; nominal propellant load is 5000 kg. The OTV operates between a circular orbit at 925-km altitude, 28.5-deg inclination, and GEO. Cargo is brought to the OTV by Shuttle and an orbital maneuvering vehicle (OMV); the OTV then takes it to GEO. The OTV can also bring cargo back from GEO for transfer by OMV to the Shuttle. OTV propellant is resupplied, and the ion thrusters are replaced, by the OMV before each sortie to GEO. At the end of mission life, the OTV's electric propulsion is used to place it in a heliocentric orbit so that the reactor will not return to earth. The nominal cargo capability to GEO is 6000 kg, with a transit time of 120 days; 1350 kg can be transferred in 90 days, and 14,300 kg in 240 days. These capabilities can be considerably increased by using separate Shuttle launches to bring up propellant and cargo or by changing to mercury propellant.

Jaffe, Leonard D.↗

Conceptual arcjet system design considerations for the SP-100 mission

Conceptual spacecraft design considerations for using 30-kW class arcjet engines as an active load for a 100-kWe SP-100 space nuclear reactor power system flight experiment are discussed. These design considerations involve configuration trades; interfaces with power, attitude and velocity control, thermal management, orbit insertion and reaction control propulsion systems; imposed environments concerned with electromagnetic noise, survivability, and ammonia exhaust plumes; and associated diagnostic instrumentation.

Zafran, Sidney↗

Proposed advanced satellite applications utilizing space nuclear power systems

A review of the status of space nuclear reactor systems and their possible applications is presented. Such systems have been developed over the past twenty years and are capable of use in various military and civilian applications in the 5-1000-kWe power range. The capabilities and limitations of the currently proposed nuclear reactor systems are summarized. Statements of need are presented from DoD, DOE, and NASA. Safety issues are identified, and if they are properly addressed they should not pose a hindrance. Applications are summarized for the DoD, DOE, NASA, and the civilian community. These applications include both low- and high-altitude satellite surveillance missions, communications satellites, planetary probes, low- and high-power lunar and planetary base power systems, broadband global telecommunications, air traffic control, and high-definition television.

Bailey, Patrick G.↗

Technology and applications of space nuclear power

Requirements for a number of potential NASA civil space missions are addressed, and the nuclear power technology base to meet these requirements is described. Particular attention is given to applications of space nuclear power to lunar, Mars, and science missions and the technology status of space nuclear power with emphasis on dynamic isotope and space nuclear reactor power systems.

Reck, Gregory M.↗

Grain size control of rhenium strip

Ensuring the desired grain size in the pure Re strip employed by the SP-100 space nuclear reactor design entails the establishment of an initial grain size in the as-received strip and the avoidance of excessive grain growth during subsequent fabrication. Pure Re tapered tensile specimens have been fabricated and tested in order to quantify the effects of grain-boundary migration. Grain size could be rendered fine and uniform by means of a rolling procedure that uses rather large reductions between short intermediate anneals. The critical strain regime varies inversely with annealing temperature.

Schuster, Gary B.↗

Toward the last frontier - A strategy for the evolutionary development of space nuclear power systems

A number of exciting mission opportunities are being considered for the 21st century, including advanced robotic science missions to the outer planets and beyond, human exploration of the Moon and Mars, and advanced space transportation systems. All of these missions will require some form of nuclear power; however, it is clear that current budgetary constraints preclude developing many different types of space nuclear power systems. This paper reviews the specific civil space missions which have been identified, the power levels and lifetimes required, and the technologies available. From this an evolutionary space nuclear power program is developed which builds upon the experience of radioisotope thermoelectric generators, dynamic isotope power systems, and space nuclear reactors. It is strongly suggested that not only does this approach make technical and budgetary sense but that it is consistent with the normal development of new technologies.

Gary L Bennett↗