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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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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Control system studies for thermionic reactors

In core thermionic reactor concepts are of interest for space missions that require electrical power in the range of a few tens of kilowatts up to several megawatts. The physical principle involved--thermionic direct conversion of heat to electricity at net efficiencies up to 15 percent--offers potential advantages when compared to other nuclear powerplant concepts. However, the integration of the thermionic diode electrode structure with high-temperature nuclear fuel materials presents new design problems and new reactor physical constraints. Among the topics that must be investigated are those associated with the control system. The results of analytical and simulation studies of thermionic reactor control performed at the Jet Propulsion Laboratory are discussed.

Hermsen, R. J.↗
NASA NTRS1987

Jet pump-drive system for heat removal

The invention does away with the necessity of moving parts such as a check valve in a nuclear reactor cooling system. Instead, a jet pump, in combination with a TEMP, is employed to assure safe cooling of a nuclear reactor after shutdown. A main flow exists for a reactor coolant. A point of withdrawal is provided for a secondary flow. A TEMP, responsive to the heat from said coolant in the secondary flow path, automatically pumps said withdrawn coolant to a higher pressure and thus higher velocity compared to the main flow. The high velocity coolant is applied as a driver flow for the jet pump which has a main flow chamber located in the main flow circulation pump. Upon nuclear shutdown and loss of power for the main reactor pumping system, the TEMP/jet pump combination continues to boost the coolant flow in the direction it is already circulating. During the decay time for the nuclear reactor, the jet pump keeps running until the coolant temperature drops to a lower and safe temperature where the heat is no longer a problem. At this lower temperature, the TEMP/jet pump combination ceases its circulation boosting operation. When the nuclear reactor is restarted and the coolant again exceeds the lower temperature setting, the TEMP/jet pump automatically resumes operation. The TEMP/jet pump combination is thus automatic, self-regulating and provides an emergency pumping system free of moving parts.

French, James R.↗
NASA NTRS2015

Shielding Development for Nuclear Thermal Propulsion

Radiation shielding analysis and development for the Nuclear Cryogenic Propulsion Stage (NCPS) effort is currently in progress and preliminary results have enabled consideration for critical interfaces in the reactor and propulsion stage systems. Early analyses have highlighted a number of engineering constraints, challenges, and possible mitigating solutions. Performance constraints include permissible crew dose rates (shared with expected cosmic ray dose), radiation heating flux into cryogenic propellant, and material radiation damage in critical components. Design strategies in staging can serve to reduce radiation scatter and enhance the effectiveness of inherent shielding within the spacecraft while minimizing the required mass of shielding in the reactor system. Within the reactor system, shield design is further constrained by the need for active cooling with minimal radiation streaming through flow channels. Material selection and thermal design must maximize the reliability of the shield to survive the extreme environment through a long duration mission with multiple engine restarts. A discussion of these challenges and relevant design strategies are provided for the mitigation of radiation in nuclear thermal propulsion.

Caffrey, Jarvis A.↗
NASA NTRS1972

Nuclear reactor descriptions for space power systems analysis

For the small, high performance reactors required for space electric applications, adequate neutronic analysis is of crucial importance, but in terms of computational time consumed, nuclear calculations probably yield the least amount of detail for mission analysis study. It has been found possible, after generation of only a few designs of a reactor family in elaborate thermomechanical and nuclear detail to use simple curve fitting techniques to assure desired neutronic performance while still performing the thermomechanical analysis in explicit detail. The resulting speed-up in computation time permits a broad detailed examination of constraints by the mission analyst.

Mccauley, E. W.↗
NASA NTRS2000

A Comparison of Brayton and Stirling Space Nuclear Power Systems for Power Levels from 1 Kilowatt to 10 Megawatts

An analytical study was conducted to assess the performance and mass of Brayton and Stirling nuclear power systems for a wide range of future NASA space exploration missions. The power levels and design concepts were based on three different mission classes. Isotope systems, with power levels from 1 to 10 kW, were considered for planetary surface rovers and robotic science. Reactor power systems for planetary surface outposts and bases were evaluated from 10 to 500 kW. Finally, reactor power systems in the range from 100 kW to 10 mW were assessed for advanced propulsion applications. The analysis also examined the effect of advanced component technology on system performance. The advanced technologies included high temperature materials, lightweight radiators, and high voltage power management and distribution.

Mason, Lee S.↗
NASA NTRS1987

NASA Growth Space Station missions and candidate nuclear/solar power systems

A brief summary is presented of a NASA study contract and in-house investigation on Growth Space Station missions and appropriate nuclear and solar space electric power systems. By the year 2000 some 300 kWe will be needed for missions and housekeeping power for a 12 to 18 person Station crew. Several Space Station configurations employing nuclear reactor power systems are discussed, including shielding requirements and power transmission schemes. Advantages of reactor power include a greatly simplified Station orientation procedure, greatly reduced occultation of views of the earth and deep space, near elimination of energy storage requirements, and significantly reduced station-keeping propellant mass due to very low drag of the reactor power system. The in-house studies of viable alternative Growth Space Station power systems showed that at 300 kWe a rigid silicon solar cell array with NiCd batteries had the highest specific mass at 275 kg/kWe, with solar Stirling the lowest at 40 kg/kWe. However, when 10 year propellant mass requirements are factored in, the 300 kWe nuclear Stirling exhibits the lowest total mass.

Heller, Jack A.↗
NASA NTRS1977

Systems definition space based power conversion systems: Executive summary

Potential space-located systems for the generation of electrical power for use on earth were investigated. These systems were of three basic types: (1) systems producing electrical power from solar energy; (2) systems producing electrical power from nuclear reactors; (3) systems for augmenting ground-based solar power plants by orbital sunlight reflectors. Configurations implementing these concepts were developed through an optimization process intended to yield the lowest cost for each. A complete program was developed for each concept, identifying required production rates, quantities of launches, required facilities, etc. Each program was costed in order to provide the electric power cost appropriate to each concept.

Source record↗
NASA NTRS1992

The NASA CSTI high capacity power project

The SP-100 Space Nuclear Power Program was established in 1983 by DOD, DOE, and NASA as a joint program to develop technology for military and civil applications. Starting in 1986, NASA has funded a technology program to maintain the momentum of promising aerospace technology advancement started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for a wide range of future space applications. The elements of the Civilian Space Technology Initiative (CSTI) High Capacity Power Project include Systems Analysis, Stirling Power Conversion, Thermoelectric Power Conversion, Thermal Management, Power Management, Systems Diagnostics, Environmental Interactions, and Material/Structural Development. Technology advancement in all elements is required to provide the growth capability, high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall project will develop and demonstrate the technology base required to provide a wide range of modular power systems compatible with the SP-100 reactor which facilitates operation during lunar and planetary day/night cycles as well as allowing spacecraft operation at any attitude or distance from the sun. Significant accomplishments in all of the project elements will be presented, along with revised goals and project timelines recently developed.

Winter, J.↗
NASA NTRS2004

Power-Conversion Concept Designed for the Jupiter Icy Moons Orbiter

The Jupiter Icy Moons Orbiter (JIMO) is a bold new mission being developed by NASA's Office of Space Science under Project Prometheus. JIMO is examining the potential of nuclear electric propulsion (NEP) technology to efficiently deliver scientific payloads to three of Jupiter's moons: Callisto, Ganymede, and Europa. A critical element of the NEP spacecraft is the space reactor power system (SRPS), consisting of the nuclear reactor, power conversion, heat rejection, and power management and distribution (PMAD).

Mason, Lee S.↗
NASA NTRS1988

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.↗
NASA NTRS1986

Nuclear reactor power for a space-based radar. SP-100 project

A space-based radar mission and spacecraft, using a 300 kWe nuclear reactor power system, has been examined, with emphasis on aspects affecting the power system. The radar antenna is a horizontal planar array, 32 X 64 m. The orbit is at 61 deg, 1088 km. The mass of the antenna with support structure is 42,000 kg; of the nuclear reactor power system, 8,300 kg; of the whole spacecraft about 51,000 kg, necessitating multiple launches and orbital assembly. The assembly orbit is at 57 deg, 400 km, high enough to provide the orbital lifetime needed for orbital assembly. The selected scenario uses six Shuttle launches to bring the spacecraft and a Centaur G upper-stage vehicle to assembly orbit. After assembly, the Centaur places the spacecraft in operational orbit, where it is deployed on radio command, the power system started, and the spacecraft becomes operational. Electric propulsion is an alternative and allows deployment in assembly orbit, but introduces a question of nuclear safety.

Bloomfield, Harvey↗
NASA NTRS2021

Compass Final Report: Nuclear Electric Propulsion (NEP)-Chemical Vehicle 1.2

Many previous studies have examined sending crews to and from Mars. The most economical involved a ‘conjunction’ class whereby the crew spends around 500 days on Mars waiting for a ‘cheap’ return. The total mission time results in over a 1000-day mission duration (about 3 years). Given the current experience level of only one year on the International Space Station (ISS), it of interest to reduce that time to only two years, thus reducing risk and minimizing required Mars surface infrastructure. The Phase 1.1 Study goal was stated as follows, “Determine the feasibility of a two-year roundtrip class Mars mission concept of operation that enables boots on Mars no later than 2036.” While the Phase1 study did show feasibility for the NEP-Chemical option, the 2036 Opposition opportunity was found to stress the schedule due to proposed technology development schedules. A 2039 Opposition (which requires even more energy than the 2036 case) was chosen as representative for Phase 1.2. Phase 1.2 also sought to further refine the concept, building on the feasibility, but addressing several challenges brought by the red team and habitat team. Given the date of 2039, nearer term technologies, primarily nuclear thermal and nuclear electric were deemed as the most viable for these missions. As will be shown, the energy required to perform such a mission in only two years (for the 2039 opportunity at least) is about three times that of the three-year conjunction mission. The rocket equation shows that this mission would then require several times the propellant of the three-year mission unless the specific impulse (ISP) of the propulsion system can be increased. Based on lunar needs, a limit of five Space Launch System (SLS) launchers with 8.4m fairings was imposed for the piloted transportation portion of the mission, limiting the size of the system. When using nuclear electric propulsion, the main limiting factor was packaging the required radiator area. The higher Isp nuclear electric propulsion (NEP) system option is described herein but with a twist: in order to keep the size of radiators packageable in one SLS and use proven reactor power system technology (~1200K reactor outlet temperature and superalloy-class Brayton) the NEP system had to be combined with a chemical propulsion system. This combination of electric propulsion and high thrust chemical was found to be useful in previous design studies combining solar electric propulsion (SEP) and chemical propulsion. Such a combination allowed the low-thrust system to provide significant change in velocity (∆V) during the interplanetary portions of the mission, thereby notably reducing the ∆V required by the high thrust system to capture and depart from the Mars gravity well. Here the high thrust ‘impulsive’ system is more efficient due to the Oberth Effect. A plethora of trades, both at the mission and system level, as well as the subsystem level were performed to develop these vehicle concepts. An entire family of NEP-Chemical transportation vehicles is described herein. The main driver and the primary focus was the piloted vehicle but additional concepts for cargo were performed using the same ‘building blocks’ in order to reduce costs and provide commonality.

Nuclear Power↗
NASA NTRS1989

Definition of an arcjet propulsion sub-system

An engineering flight demonstration of a 100 kW3 Space Reactor Power System is planned for the mid to late 1990s. An arcjet based propulsion subsystem will be included on the flight demonstraction as a secondary experiment. Two studies, sponsored by the Kay Technologies Directorate of the SDI Organization and managed by the Jet Propulsion Laboratory are currently under way to define that propulsion subsystem. The principal tasks of those contracts and the plans for two later phases, an experimental verification of the concept and a flight qualification/delivery of a flight unit, are described.

Price, Theodore W.↗
NASA NTRS1993

NTP comparison process

The systems engineering process for the concept definition phase of the program involves requirements definition, system definition, and consistent concept definition. The requirements definition process involves obtaining a complete understanding of the system requirements based on customer needs, mission scenarios, and nuclear thermal propulsion (NTP) operating characteristics. A system functional analysis is performed to provide a comprehensive traceability and verification of top-level requirements down to detailed system specifications and provides significant insight into the measures of system effectiveness to be utilized in system evaluation. The second key element in the process is the definition of system concepts to meet the requirements. This part of the process involves engine system and reactor contractor teams to develop alternative NTP system concepts that can be evaluated against specific attributes, as well as a reference configuration against which to compare system benefits and merits. Quality function deployment (QFD), as an excellent tool within Total Quality Management (TQM) techniques, can provide the required structure and provide a link to the voice of the customer in establishing critical system qualities and their relationships. The third element of the process is the consistent performance comparison. The comparison process involves validating developed concept data and quantifying system merits through analysis, computer modeling, simulation, and rapid prototyping of the proposed high risk NTP subsystems. The maximum amount possible of quantitative data will be developed and/or validated to be utilized in the QFD evaluation matrix. If upon evaluation of a new concept or its associated subsystems determine to have substantial merit, those features will be incorporated into the reference configuration for subsequent system definition and comparison efforts.

Corban, Robert↗
NASA NTRS2005

STS-114: Discovery Day 13 Mission Status Briefing

LeRoy Cain, STS-114 Ascent/Entry Flight Director, takes a solo stand with the Press in this briefing. He reports that the vehicle is in good shape, consumable status is excellent, and the shuttle crew is in high spirits and preparing for de-orbit and landing. LeRoy and his team have completed the entry system check up, flight control check up, reactor control system check up, and noted that all are at nominal performance; weather forecast is very good, the Entry team is ready and looking forward to de-orbit and landing at the Kennedy Space Center on Monday, August 8th. Re-entry, personal feelings, Columbia accident, data gathering, consumable situation, back up sites, weather, communication block out, night and day landing, and Commander Collin's piloting skills during night flight are some of the topics covered with the News media.

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