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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Evolving the SP-100 reactor in order to boost large payloads to GEO and to low lunar orbit via nuclear-electric propulsion

In striving to reduce exploration cost and exploration risks, a crucial aspect of the plans is program continuity, i.e., the continuing application of a given technology over a long period so that experience will accumulate from extended testing here on earth and from a diversity of applications in space. An integrated view needs to be formed of the missions SEI will carry out, near term as well as far, and of the ways in which these missions can mutually support one another. Near term programs should be so constituted as to provide for the long term missions both the enabling technologies and the accumulation of experience they need. In achieving this, missions in earth orbit should both evolve and show the technologies crucial to long term missions on the lunar surfaces, and the program for the lunar labs should evolve and show the enabling technologies for exploration of the surface of Mars and for flights of human beings to Mars and return. In the near term, the program for the Space Station should be directed and funded to develop and demonstrate the solar Brayton power plant that will be most useful as the power generator for the SP-100 nuclear reactor.

English, Robert E.↗
NASA NTRS1991

A cermet fuel reactor for nuclear thermal propulsion

Work on the cermet fuel reactor done in the 1960's by General Electric (GE) and the Argonne National Laboratory (ANL) that had as its goal the development of systems that could be used for nuclear rocket propulsion as well as closed cycle propulsion system designs for ship propulsion, space nuclear propulsion, and other propulsion systems is reviewed. It is concluded that the work done in the 1960's has demonstrated that we can have excellent thermal and mechanical performance with cermet fuel. Thousands of hours of testing were performed on the cermet fuel at both GE and AGL, including very rapid transients and some radiation performance history. We conclude that there are no feasibility issues with cermet fuel. What is needed is reactivation of existing technology and qualification testing of a specific fuel form. We believe this can be done with a minimum development risk.

Kruger, Gordon↗
NASA NTRS1991

Pellet bed reactor for nuclear propelled vehicles: Part 2: Missions and vehicle integration trades

Mission and vehicle integration tradeoffs involving the use of the pellet bed reactor (PBR) for nuclear powered vehicles is discussed, with much of the information being given in viewgraph form. Information is given on propellant tank geometries, shield weight requirements for conventional tank configurations, effective specific impulse, radiation mapping, radiation dose rate after shutdown, space transfer vehicle design data, a Mars mission summary, sample pellet bed nuclear orbit transfer vehicle mass breakdown, and payload fraction vs. velocity increment.

Haloulakos, V. E.↗
NASA NTRS1991

Atmospheric pressure flow reactor: Gas phase chemical kinetics under tropospheric conditions without wall effects

A flow reactor for simulating the interaction in the troposphere is set forth. A first reactant mixed with a carrier gas is delivered from a pump and flows through a duct having louvers therein. The louvers straighten out the flow, reduce turbulence and provide laminar flow discharge from the duct. A second reactant delivered from a source through a pump is input into the flowing stream, the second reactant being diffused through a plurality of small diffusion tubes to avoid disturbing the laminar flow. The commingled first and second reactants in the carrier gas are then directed along an elongated duct where the walls are spaced away from the flow of reactants to avoid wall interference, disturbance or turbulence arising from the walls. A probe connected with a measuring device can be inserted through various sampling ports in the second duct to complete measurements of the first and second reactants and the product of their reaction at selected XYZ locations relative to the flowing system.

Koontz, Steven L.↗
NASA NTRS1992

High aspect reactor vessel and method of use

An improved bio-reactor vessel and system useful for carrying out mammalian cell growth in suspension in a culture media are presented. The main goal of the invention is to grow and maintain cells under a homogeneous distribution under acceptable biochemical environment of gas partial pressures and nutrient levels without introducing direct agitation mechanisms or associated disruptive mechanical forces. The culture chamber rotates to maintain an even distribution of cells in suspension and minimizes the length of a gas diffusion path. The culture chamber design is presented and discussed.

Wolf, David A.↗
NASA NTRS1991

Surface reaction and pore diffusion in flow-tube reactors

The interaction of gas diffusion with surface reaction in porous solids is discussed and applied specifically to heterogeneous rate measurements in flow-tube reactors. External diffusion to the outer surface of a reactive solid, internal diffusion within the pores, surface reaction, and laminar flow are considered. A procedure is developed to correct observed surface rate constants for the interaction of these processes. Measured surface areas and bulk densities are used to construct a semiempirical model for porous diffusion in vapor-formed HNO3-H2O ices which are used to simulate polar stratospheric cloud surfaces. The model is tested experimentally by varying the thickness of these ices from about 15 to 120 microns. The results are consistent with the model predictions and show that the HNO3-H2O ices used are highly porous, and the internal surface must be considered in calculating kinetic parameters from observed loss rates. The best fit of the data yields a tortuosity factor of 3.3 +/-1.1 for the ice substrates.

Keyser, Leon F.↗
NASA NTRS1991

Advanced development of immobilized enzyme reactors

Fixed-bed reactors have been used at NASA-Marshall to purify wastewater generated by an end-use equipment facility, on the basis of a combination of multifiltration unibeds and enzyme unibeds. The enzyme beds were found to effectively remove such targeted organics as urea, alcohols, and aldehydes, down to levels lying below detection limits. The enzyme beds were also found to remove organic contaminants not specifically targeted.

Jolly, Clifford D.↗
NASA NTRS1991

Surface morphologies and photoluminescence of diamond films deposited in a hot filament reactor

A diamond film made of (100)-oriented diamond crystallites has relatively flat surfaces in parallel with the silicon surface. This is desirable because it provides a smoother surface of the diamond film. The difficulty in retaining the (100)-oriented diamond crystallites is strongly influenced by the growth temperature. This paper reports the results from a study on the surface morphologies of diamond films deposited in a hot filament reactor at reduced substrate temperature compared to that deposited at higher temperature.

Srivinyunon, T.↗
NASA NTRS1991

Survey of electronics capability for SP-100 space reactor power system applications

Because of reports indicating improvements in the radiation tolerance of some electronic parts, a survey was recently performed by SP-100 project personnel to determine the advisability of revising SP-100 SRPS (space reactor power systems) allowable neutron and gamma dose rates in order to reduce the size and mass of the radiation shield and thereby achieve system mass reductions. The survey results indicate that recent developments to increase the radiation tolerance of a limited set of electronics parts do not justify increasing the allowable SP-100 dose rates for electronic components. Specifically, the recent improvements on a limited set of parts do not justify increasing the current SP-100 allowable specifications of 5 x 10 exp 5 rads gamma dose and 1 x 10 exp 13 neutrons/sq cm fluence. However, if the improvements of 108 rads for gammas and 10 exp 15 neutrons/sq cm can be extended to a wide range of parts, significant mass savings would result.

Manvi, Ram↗
NASA NTRS1991

Approach to developing reliable space reactor power systems

During Phase II, the Engineering Development Phase, the SP-100 Project has defined and is pursuing a new approach to developing reliable power systems. The approach to developing such a system during the early technology phase is described along with some preliminary examples to help explain the approach. Developing reliable components to meet space reactor power system requirements is based on a top-down systems approach which includes a point design based on a detailed technical specification of a 100-kW power system. The SP-100 system requirements implicitly recognize the challenge of achieving a high system reliability for a ten-year lifetime, while at the same time using technologies that require very significant development efforts. A low-cost method for assessing reliability, based on an understanding of fundamental failure mechanisms and design margins for specific failure mechanisms, is being developed as part of the SP-100 Program.

Mondt, Jack F.↗
NASA NTRS1993

Advanced propulsion engine assessment based on a cermet reactor

A preferred Pratt & Whitney conceptual Nuclear Thermal Rocket Engine (NTRE) has been designed based on the fundamental NASA priorities of safety, reliability, cost, and performance. The basic philosophy underlying the design of the XNR2000 is the utilization of the most reliable form of ultrahigh temperature nuclear fuel and development of a core configuration which is optimized for uniform power distribution, operational flexibility, power maneuverability, weight, and robustness. The P&W NTRE system employs a fast spectrum, cermet fueled reactor configured in an expander cycle to ensure maximum operational safety. The cermet fuel form provides retention of fuel and fission products as well as high strength. A high level of confidence is provided by benchmark analysis and independent evaluations.

Parsley, Randy C.↗
NASA NTRS1993

Particle bed reactor modeling

The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

Sapyta, Joe↗
NASA NTRS1992

Flow effects in a vertical CVD reactor

A model is presented to simulate the non-Boussinesq flow in a vertical, two-dimensional, chemical vapor deposition reactor under atmospheric pressure. Temperature-dependent conductivity, mass diffusivity, viscosity models, and reactive species mass transfer to the substrate are incorporated. In the limits of small Mach number and small aspect ratio, asymptotic expressions for the flow, temperature, and species fields are developed. Soret diffusion effects are also investigated. Analytical solutions predict an inverse relationship between temperature field and concentration field due to Soret effects. This finding is consistent with numerical simulations, assisting in the understanding of the complex interactions amongst the flow, thermal, and species fields in a chemically reacting system.

Young, G. W.↗
NASA NTRS1993

Two-dimensional thermal-hydraulics analyses of the Pellet Bed Reactor for Nuclear Thermal Propulsion

Thermal-hydraulics design and analyses of the Pellet Bed Reactor for nuclear thermal propulsion are performed using the nuclear propulsion thermal-hydraulic analysis model to determine the 2D steady-state temperature, pressure, and flow fields in the core and optimize the orificing in the hot-frit to avoid hot spots in the core at full power operation. Results show that by properly adjusting the axial porosity profile in the hot frit, hot spots in the core can be essentially eliminated during full power operation. This important accomplishment is achieved at the expense of slightly larger pressure losses in the core because of flow restriction at the hot frit. However, the overall pressure losses is only about 11 percent of the propellant inlet pressure.

Morley, Nicholas J.↗
NASA NTRS1992

Catalytic ignition model in monolithic reactor with in-depth reaction

A transient model has been developed to study ignition in a monolithic catalytic reactor. Special features are the inclusion of thermal and species structures in the porous catalytic layer and the resolution of small-time-scale events. Catalyst loading is used as a parameter to study these structure variations before and after ignition. Regions where the catalytic reaction is kinetically controlled and regions where the reaction is diffusionally controlled are identified in both steady and transient states.

Tien, Ta-Ching↗
NASA NTRS1952

Calculation of Internal Pressures in the Fuel Tube of a Nuclear Reactor

General procedures for computing internal pressures in fuel tubes of nuclear reactors are described and the effects on the pressure of varying neutron flux, fissioning material, and operating temperatures are discussed. A general proof is given that during pile operation each fission product is monotonically increasing and therefore a maximum amount of all elements is present at the time of shit down. The post-shutdown build-up of elements that are held in check during pile operation because of their inordinately high capture cross sections is calculated quantitatively. An account of chemical interactions between the many fission-product elements and the resulting effect on the total pressure completes the discussion. The general methods are illustrated by calculations applied to a system consisting of 90 percent enriched U235 in the form of UO2 packed into a hollow metal cylinder or "pin", operating at a flux of 8 x 10(exp 14) at 2000 F. Calculations of the pressure inside a pin are made with and without a sodium metal heat-transfer additive. The bulk of the pressure is shown to depend on the four elements, xenon, krypton, rubidium, and cesium; the amount of free oxygen, however, was also significant. For a shutdown time of 10(exp 6) seconds, the pressure was about 100 atmospheres.

Rosenbaum, B. M.↗
NASA NTRS1992

Design of A CVD Reactor for the Deposition of Diamond in A Microgravity Environment

There is a growing body of theoretical and experimental evidence suggesting that the uniformity, rate, adhesion, quality, and other key properties of Chemical Vapor Deposition (CVD) diamond coatings are influenced by the gas mixing kinetics in the thermal plasma environment of the reaction chamber. The implementation of, for example, Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) process in microgravity has, thus, been suggested. Such a diamond deposition system, which overcomes the limitations of present systems and which is distiguishable from them by the use of high pressure MPECVD and recirculation of the would be effluent hydrogen and carbon, is described. Given the key fact that there is nothing in the effluent of the MPECVD process that is truly a byproduct or 'waste', the system can, at least in principle, lend itself to being closed loop yet dynamic. The exhaust contains hydrogen and carbon species which can be recirculated to the plasma reactor, that is, since there are no unusable reaction byproducts, the effluent can be fed back to the reaction chamber with no detriment, thus allowing deployment in a microgravity environment.

M L Languell↗
NASA NTRS1996

GLSENS: A Generalized Extension of LSENS Including Global Reactions and Added Sensitivity Analysis for the Perfectly Stirred Reactor

A generalized version of the NASA Lewis general kinetics code, LSENS, is described. The new code allows the use of global reactions as well as molecular processes in a chemical mechanism. The code also incorporates the capability of performing sensitivity analysis calculations for a perfectly stirred reactor rapidly and conveniently at the same time that the main kinetics calculations are being done. The GLSENS code has been extensively tested and has been found to be accurate and efficient. Nine example problems are presented and complete user instructions are given for the new capabilities. This report is to be used in conjunction with the documentation for the original LSENS code.

Bittker, David A.↗