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Nuclear technology for the year 2000

Description: Eighteen papers and abstracts are presented under the following session headings: space nuclear power, health physics and dosimetry, nuclear design and thermal hydraulics, nuclear diagnostics, and fusion technology and plasma physics. The papers were processed separately for the data base. (DLC)
Date: January 1, 1987
Partner: UNT Libraries Government Documents Department

A comparison of propulsion systems for potential space mission applications

Description: A derivative of the NERVA nuclear rocket engine was compared with a chemical propulsion system and a nuclear electric propulsion system to assess the relative capabilities of the different propulsion system options for three potential space missions. The missions considered were (1) orbital transfer from low earth orbit (LEO) to geosynchronous earth orbit (GEO), (2) LEO to a lunar base, and (3) LEO to Mars. The results of this comparison indicate that the direct-thrust NERVA-derivative nuclear rocket engine has the best performance characteristics for the missions considered. The combined high thrust and high specific impulse achievable with a direct-thrust nuclear stage permits short operating times (transfer times) comparable to chemical propulsion systems, but with considerably less required propellant. While nuclear-electric propulsion systems are more fuel efficient than either direct-nuclear or chemical propulsion, they are not stand-alone systems, since their relatively low thrust levels require the use of high-thrust ferry or lander stages in high gravity applications such as surface-to-orbit propulsion. The extremely long transfer times and inefficient trajectories associated with electric propulsion systems were also found to be a significant drawback.
Date: January 1, 1987
Creator: Harvego, E.A. & Sulmeisters, T.K.
Partner: UNT Libraries Government Documents Department

Development of a high-heat-flux target for multimegawatt, multisecond neutral beams at ORNL

Description: A high-heat-flux target has been developed for intercepting multimegawatt, multisecond neutral beam power at the Oak Ridge National Laboratory (ORNL). Water-cooled copper swirl tubes are used for the heat transfer medium; these tubes exhibit an enhancement in burnout heat flux over conventional axial-flow tubes. The target consists of 126 swirl tubes (each 0.95 cm in outside diameter with 0.16-cm-thick walls and approx. =1 m long) arranged in a V-shape. Two arrays of parallel tubes inclined at an angle ..cap alpha.. to the beam axis form the V-shape, and this geometry reduces the surface heat flux by a factor of 1/sin ..cap alpha.. (for the present design, ..cap alpha.. =13/sup 0/ and 21/sup 0/). In tests with the ORNL long-pulse ion source (13- by 43-cm grid), the target has handled up to 3-MW, 30-s beam pulses with no deleterious effects. The peak power density was estimated at approx. =15 kW/cm/sup 2/ normal to the beam axis (5.4 kW/cm/sup 2/ maximum on tube surfaces). The water flow rate through the target was 41.6 L/s (660 gpm) or 0.33 L/s (5.2 gpm) per tube (axial flow velocity = 11.6 m/s). The corresponding pressure drop across the target was 1.14 MPa (165 psi) with an inlet pressure of 1.45 MPa (210 psia). Data are also presented from backup experiments in which individual tubes were heated by a small ion source (10-cm-diam grid) to characterize tube performance. These results suggest that the target should handle peak power densities in the range 25 to 30 kW/cm/sup 2/ normal to the beam axis (approx. =10 kW/cm/sup 2/ maximum on tube surfaces) with the present flow parameters. This translates to beam power levels of 5 to 6 MW for equivalent beam optics.
Date: January 1, 1984
Creator: Combs, S.K.; Milora, S.L.; Bush, C.E.; Foster, C.A.; Haselton, H.H.; Hayes, P.H. et al.
Partner: UNT Libraries Government Documents Department

Nuclear reactor power for an electrically powered orbital transfer vehicle

Description: To help determine the systems requirements for a 300-kWe space nuclear reactor power system, a mission and spacecraft have been examined which utilize electric propulsion and this nuclear reactor 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 trip 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.
Date: January 1, 1987
Creator: Jaffe, L.; Beatty, R.; Bhandari, P.; Chow, E.; Deininger, W.; Ewell, R. et al.
Partner: UNT Libraries Government Documents Department

Nuclear powered Mars cargo transport mission utilizing advanced ion propulsion

Description: Nuclear-powered ion propulsion technology was combined with detailed trajectory analysis to determine propulsion system and trajectory options for an unmanned cargo mission to Mars in support of manned Mars missions. A total of 96 mission scenarios were identified by combining two power levels, two propellants, four values of specific impulse per propellant, three starting altitudes, and two starting velocities. Sixty of these scenarios were selected for a detailed trajectory analysis; a complete propulsion system study was then conducted for 20 of these trajectories. Trip times ranged from 344 days for a xenon propulsion system operating at 300 kW total power and starting from lunar orbit with escape velocity, to 770 days for an argon propulsion system operating at 300 kW total power and starting from nuclear start orbit with circular velocity. Trip times for the 3 MW cases studied ranged from 356 to 413 days. Payload masses ranged from 5700 to 12,300 kg for the 300 kW power level, and from 72,200 to 81,500 kg for the 3 MW power level.
Date: January 1, 1987
Creator: Galecki, D.L. & Patterson, M.J.
Partner: UNT Libraries Government Documents Department

GES (Ground Engineering System) test site preparation

Description: Activities are under way at Hanford to convert the 309 containment building and its associated service wing to a nuclear test facility for the Ground Engineering System (GES) test. Conceptual design is about 80% complete, encompassing facility modifications, a secondary heat transport system, a large vacuum system, a test article cell and handing system, control and data handling systems, and safety andl auxiliary systems. The design makes extensive use of existing equipment to minimize technical risk and cost. Refurbishment of this equipment is 25% complete. Cleanout of some 1000 m/sup 3/ of equipment from the earlier reactor test in the facility is 85% complete. An Environmental Assessment was prepared and revised to incorporate Department of Energy (DOE) comments. It is now in the DOE approval chain, where a Finding of No Significant Impact is expected. During the next year, definite design will be well advanced, long-lead procurements will be initiated, construction planning will be completed, an operator training plan will be prepared, and the site (preliminary) safety analysis report will be drafted.
Date: October 1, 1987
Creator: Cox, C.M.; Mahaffey, M.K.; Miller, W.C.; Schade, A.R. & Toyoda, K.G.
Partner: UNT Libraries Government Documents Department

Inertial fusion power for space applications

Description: More than thirty-seven design concepts have been proposed for terrestrial ICF power plants. The design space is large because of the many allowable driver and reaction chamber combinations. These design studies have illustrated advantages of ICF power plants over other sources in lower impact on the environment, high safety, and almost no dependence on consumables like fuel. The fact that, once built, a 1000 MW/sub e/ ICF power plant would require only 240 kg of deuterium and from 770 to 9260 kg of lithium to run for five years (at 70% capacity factor) makes it potentially attractive for space power also. However, the designs proposed to date have emphasized features that would make the plant attractive for terrestrial applications, where economics, efficiency, and environmental considerations dominate. The resulting plants are large and contain many very heavy components that would not be at attractive for space applications. In this paper, we evaluate alternative ICF driver and reactor technologies using space application criteria and also discuss how some of those technologies can be altered to produce smaller, lighter fusion power sources for space.
Date: May 19, 1986
Creator: Meier, W.R.; Hogan, W.J.; Hoffman, N.J.; Murray, K.A. & Olson, R.E.
Partner: UNT Libraries Government Documents Department

Forming of metal components for radioisotope heat sources

Description: Flight-quality iridium components can be fabricated from iridium alloys by modifying standard production processes. A large quantity of metrological and NDE data support the quality of these devices, which, in turn, justify their use in containing plutonium fuel for space system applications.
Date: January 1, 1984
Creator: Johnson, E.W.
Partner: UNT Libraries Government Documents Department

Fabrication of selenide segmented elements

Description: Processes are described for the fabrication of P- and N-type elements with high-efficiency selenide segments. Bonded hot and cold caps were attached to these elements with techniques based on processes developed in successful TRANSIT and Ring converter programs. An iron barrier was introduced in the segmented P-type element between the (Cu,Ag)/sub 2/Se and (Bi,Sb)/sub 2/Te/sub 3/ layers. This was made necessary by the known degradation in thermoelectric properties of (Bi,Sb)/sub 2/Te/sub 3/ contaminated with copper. Zero current thermal gradient tests of the segmented P-type element show the iron barrier successfully prevents copper contamination of the (Bi,Sb)/sub 2/Te/sub 3/.
Date: March 1, 1980
Creator: Elsner, N.B.; Chin, J. & Reynolds, G.H.
Partner: UNT Libraries Government Documents Department

Engineering data bases for refractory alloys

Description: Refractory alloys based on niobium, molybdenum, tantalum, and tungsten are required for the multi-100kW(e) space nuclear reactor power concepts that have been assessed in the SP-100 Program because of the extremely high temperatures involved. A review is presented of the technology efforts on the candidate refractory alloys in the areas of availability/fabricability, mechanical properties, irradiation effects, and compatibility. Of the niobium-base alloys, only Nb-1Zr has a data base that is sufficiently comprehensive for the high level of confidence required in the reference-alloy selection process for the reactor concept to be tested in the Ground Engineering System (GES) Phase of the SP-100 Program. Based on relatively short-term tests, the alloy PWC-11 (Nb-1Zr-0.1C) appears to have significantly greater creep strength than Nb-1Zr; however, concerns as to whether this precipitation-hardened alloy will remain thermally stable during seven years of full-power reactor operation need to be resolved. Additional information on the reference GES alloy will be needed for the detailed engineering design of a space power system and the fabrication of prototypical GES test components. Expedient development and demonstration of an adequate total manufacturing capability will be required if a high risk of significant schedule slippages and cost overruns is to be avoided. 4 refs., 1 fig., 3 tabs.
Date: January 1, 1985
Creator: Cooper, R.H. Jr. & Harms, W.O.
Partner: UNT Libraries Government Documents Department

Transactions of the fifth symposium on space nuclear power systems

Description: This paper contains the presented papers at the fourth symposium on space nuclear power systems. Topics of these paper include: space nuclear missions and applications, reactors and shielding, nuclear electric and nuclear propulsion, high-temperature materials, instrumentation and control, energy conversion and storage, space nuclear fuels, thermal management, nuclear safety, simulation and modeling, and multimegawatt system concepts. (LSP)
Date: January 1, 1988
Creator: El-Genk, M.S. & Hoover, M.D. (eds.)
Partner: UNT Libraries Government Documents Department

Transactions of the fourth symposium on space nuclear power systems

Description: This paper contains the presented papers at the fourth symposium on space nuclear power systems. Topics of these papers include: space nuclear missions and applications, reactors and shielding, nuclear electric and nuclear propulsion, refractory alloys and high-temperature materials, instrumentation and control, energy conversion and storage, space nuclear fuels, thermal management, nuclear safety, simulation and modeling, and multimegawatt system concepts. (LSP)
Date: January 1, 1987
Creator: El-Genk, M.S. & Hoover, M.D. (eds.)
Partner: UNT Libraries Government Documents Department

The oxidation of Ba dosed Mo(100) surfaces with O/sub 2/ at moderately high temperatures

Description: The oxidation of Mo(100) and Ba-covered Mo(100) by O/sub 2/ have been examined at moderately high temperature (700 to 1400/sup 0/K) using x-ray photoelectron spectroscopy. Results indicate that the Ba or BaO overlayer retards but does not prevent oxidation of the underlying Mo surface. The high temperature surface chemistry of the O/Ba/Mo surface is described. 11 refs., 3 figs.
Date: January 1, 1987
Creator: Rogers, J.W. Jr.; Blair, D.S. & Paffett, M.T.
Partner: UNT Libraries Government Documents Department

Swelling and tensile properties of EBR-II-irradiated tantalum alloys for space reactor applications

Description: The tantalum alloys T-111, ASTAR-811C, Ta-10 W, and unalloyed tantalum were examined following EBR-II irradiation to a fluence of 1.7 x 10/sup 26/ neutrons/m/sup 2/ (E > 0.1 MeV) at temperatures from 650 to 950 K. Swelling was found to be negligible for all alloys; only tantalum was found to exhibit swelling, 0.36%. Tensile testing revealed that irradiated T-111 and Ta-10 W are susceptible to plastic instability, but ASTAR-811C and tantalum were not. The tensile properties of ASTAR-811C appeared adequate for current SP-100 space nuclear reactor designs. Irradiated, oxygen-doped T-111 exhibited no plastic deformation, and the abrupt failure was intergranular in nature. The absence of plastic instability in ASTAR-811C is encouraging for alloys containing carbide precipitates. These fine precipitates might prevent dislocation channeling, which leads to plastic instability in many bcc metals after irradiation. 10 refs., 13 figs., 8 tabs.
Date: January 1, 1985
Creator: Grossbeck, M.L. & Wiffen, F.W.
Partner: UNT Libraries Government Documents Department

Transport vehicle for manned Mars missions powered by inertial confinement fusion

Description: Inertial confinement fusion (ICF) is an ideal engine power source for manned spacecraft to Mars because of its inherently high power-to-mass ratios and high specific impulses. We have produced a concept for a vehicle powered by ICF and utilizing a magnetic thrust chamber to avoid plasma thermalization with wall structures and the resultant degradation of specific impulse that are unavoidable with the use of mechanical thrust chambers. This vehicle is capable of 100-day manned Mars missions with a 100-metric-ton payload and a total vehicle launch mass near 6000 metric tons, based on advanced technology assumed to be available by A.D. 2020. Such short-duration missions minimize radiation exposures and physiological deterioration of astronauts.
Date: June 26, 1987
Creator: Orth, C.D.; Klein, G.; Sercel, J.; Hoffman, N.; Murray, K. & Chang-Diaz, F.
Partner: UNT Libraries Government Documents Department

Creep behavior of tungsten/niobium and tungsten/niobium-1 percent zirconium composites

Description: The creep behavior and microstructural stability of tungsten fiber-reinforced niobium and niobium-1% zirconium was determined at 1400 and 1500{degree}K in order to assess the potential of this material for use in advanced space power systems. The creep behavior of the composite materials could be described a power law creep equation. A linear relationship was found to exist between the minimum creep rate of the composite and the inverse of the composite creep rupture life. The composite materials had an order of magnitude increase in stress to achieve 1 percent creep strain and in rupture strength at test temperatures of 1400 and 1500{degree}K compared to unreinforced material. The composite materials were also stronger than the unreinforced materials by an order of magnitude when density was taken into consideration. Results indicate significant potential improvement in high temperature properties and mass reduction for space power system components. 12 refs., 1 2 figs., 2 tabs.
Date: January 1, 1988
Creator: Petrasek, D.W. & Titran, R.H.
Partner: UNT Libraries Government Documents Department

Preliminary upper axial shield design for space reactor ground test

Description: A prototype of the SP-100 space reactor will be tested in a vacuum environment on the ground to verify the design prior to flight applications. Neutronic calculations are under way to design shielding that will provide the appropriate operational protection for both personnel and instrumentation, and will not compromise any important flight-type conditions of the reactor and shield system. This document describes the preliminary design of the shielding system. 1 ref., 11 figs.
Date: November 1, 1987
Creator: Carter, L.L. & Bunch, W.L.
Partner: UNT Libraries Government Documents Department

Overview of the 1985 NASA Lewis Research Center SP-100 free-piston Stirling engine activities

Description: An overview of the 1985 (NASA) Lewis Research Center free-piston Stirling engine activities in support of the SP-100 Program is presented. The SP-100 program is being conducted in support of the Department of Advanced Research Projects Agency (DARPA) and the Department of Energy (DOE), and NASA. This effort is keyed on the design, fabrication, assembly, and testing of a 25 kW(e) Stirling space-power technology-feasibility demonstrator engine. Another facet of the SP-100 project covers the status of a 9000-h goal endurance test conducted on a 2 kW(e) free-piston Stirling/linear alternator system employing hydrostatic gas bearings. Dynamic balancing of the RE-1000 engine (a 1 kW(e) free-piston Stirling engine) using a passive dynamic absorber is discussed, along with the results of a parametric study showing the relationships of Stirling power converter specific weight and efficiency as functions of Stirling engine heater to cooler temperature ratio. Planned tests are described covering a hydrodynamic gas bearing concept for potential SP-100 application.
Date: January 1, 1985
Creator: Slaby, J.G.
Partner: UNT Libraries Government Documents Department

Requirements and cost considerations for a Combined Space Nuclear Reactor Test Facility

Description: A number of US military programs are currently considering nuclear power systems for space propulsion and electric power applications. These space power systems will each require expensive ground testing of nuclear components and systems prior to deployment in space. In some cases, the ground test facility construction and operating costs can represent a major portion of the total program budget. To minimize the costs to individual programs, consideration is given to the potential for reducing total costs by constructing a single facility in which two or more test programs can be conducted simultaneously. This concept is referred to as a Combined Space Nuclear Reactor Test Facility. This paper presents the results of a study in which the requirements and costs associated with conducting two space nuclear reactor ground test programs separately and in combination were examined. The findings of this study were that, for all new construction, the costs associated with construction and operation of a combined Space Nuclear Reactor Test Facility were substantially less than those associated with constructing and operating separate facilities. However, if existing test support facilities can be used, the potential costs of the two options are comparable. 11 refs., 5 figs., 2 tabs.
Date: January 1, 1987
Creator: Harvego, E.A.; Park, D.L.; Ramsthaler, J.H.; Reed, W.C.; Whitbeck, J.F. & Gillies, B.B.
Partner: UNT Libraries Government Documents Department

Revised MITG design, fabrication procedure, and performance predictions

Description: The design, analysis, and key features of the Modular Isotopic Thermoelectric Generator (MITG) were described in a 1981 IECEC paper; and the design, fabrication, testing, and post-test analysis of test assemblies simulating prototypical MITG modules were described in preceding papers in these proceedings. These analyses succeeded in identifying and explaining the principal causes of thermal-stress problems encountered in the tests, and in confirming the effectiveness of design changes for alleviating them. The present paper presents additional design improvements for solving these and other problems, and describes new thermoelectric material properties generated by independent laboratories over the past two years. Based on these changes and on a revised fabrication procedure, it presents a reoptimization of the MITG design and computes the power-to-weight ratio for the revised design. That ratio is appreciably lower than the 1981 prediction, primarily because of changes in material properties; but it is still much higher than the specific power of current-generation RTGs.
Date: January 1, 1983
Creator: Schock, A.
Partner: UNT Libraries Government Documents Department

Design of a high-power density Ljungstrom turbine using potassium as a working fluid

Description: The ability to generate large quantities of high-quality power in space will be necessary to meet the needs of many proposed future space programs. The Pacific Northwest Laboratory is studying an advanced multi-megawatt space power system employing a liquid metal Rankine power cycle. This paper examines more closely one component of the system, the power turbine. The turbine design selected for this system is a counter-rotating radial-outflow machine developed in the early twentieth century by two brothers, Fredrik and Birger Ljungstroem turbine was selected because it provides a compact, high-power-density turbine with balanced rotational inertia and is tolerant of moisture in the working fluid. In commercial operation, Ljungstroem turbines have demonstrated excellent rapid start capabilities and good overall efficiency. Moreover, the disadvantages that have hindered its use in conventional power plants are tied to the steam's very large change in specific volume. These disadvantages are circumvented in a machine using potassium for a working fluid. A preliminary design study indicates that high-power turbines, using potassium as a working fluid, are feasible for the Ljungstroem turbine, and that Ljungstroem turbines of 200 MW and greater could easily fit into the cargo bay of the space shuttle. 10 refs., 5 figs. 3 tabs.
Date: April 1, 1986
Creator: Coomes, E.P.; Dodge, R.E.; Wilson, D.G. & McCabe, S.J.
Partner: UNT Libraries Government Documents Department