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Fabric composite radiators for space nuclear power applications. Final report, March 1993

Description: Nuclear power systems will be required to provide much greater power levels for both civilian and defense space activities in the future than an currently needed. Limitations on the amount of usable power from radioisotope thermal generators and the limited availability of radioisotope heat source materials lead directly to the conclusion that nuclear power reactors will be needed to enhance the exploration of the solar system as well as to provide for an adequate defense. Lunar bases and travel to the Martian surface will be greatly enhanced by the use of high levels of nuclear power. Space based radar systems requiring many kilowatts of electrical power can provide intercontinental airline traffic control and defense early warning systems. Since the, figure of merit used in defining any space power system is the specific power, the decrease in die mass of any reactor system component will yield a tremendous benefit to the overall system performance. Also, since the heat rejection system of any power system can make up a large portion of the total system mass, any reduction in the mass of the heat rejection radiators will significantly affect the performance of the power system. Composite materials which combine the high strength, flexibility, and low mass characteristics of Si% based fibers with the attractive compatibility and heat transfer features of metallic foils, have been proposed for use m a number of space radiator applications. Thus, the weave of the fabric and the high strength capability of the individual fibers are combined with the high conductivity and chemical stability of a metallic liner to provide a light weight, flexible alternative to heavy, rigid, metallic radiator structural containers. The primary focus of this investigation revolves around two applications of the fabric composite materials, notably a fabric heat pipe radiator design and the Bubble Membrane ...
Date: March 24, 1993
Creator: Klein, A.C.; Al-Baroudi, H.; Gulshan-Ara, Z.; Kiestler, W.C.; Snuggerud, R.D.; Abdul-Hamid, S.A. et al.
Partner: UNT Libraries Government Documents Department

A Gas-Cooled Reactor Surface Power System

Description: A human outpost on Mars requires plentiful power to assure survival of the astronauts. Anywhere from 50 to 500 kW of electric power (kWe) will be needed, depending on the number of astronauts, level of scientific activity, and life- cycle closure desired. This paper describes a 250-kWe power system based on a gas-cooled nuclear reactor with a recuperated closed Brayton cycle conversion system. The design draws upon the extensive data and engineering experience developed under the various high-temperature gas cooled reactor programs and under the SP-100 program. The reactor core is similar in power and size to the research reactors found on numerous university campuses. The fuel is uranium nitide clad in Nb 1 %Zr, which has been extensively tested under the SP-I 00 program The fiel rods are arranged in a hexagonal array within a BeO block. The BeO softens the spectrum, allowing better use of the fbel and stabilizing the geometty against deformation during impact or other loadings. The system has a negative temperature feedback coefficient so that the power level will automatically follow a variable load without the need for continuous adjustment of control elements. Waste heat is removed by an air-cooled heat exchanger using cold Martian air. The amount of radioactivity in the reactor at launch is very small (less than a Curie, and about equal to a truckload of uranium ore). The system will need to be engineered so that criticality cannot occur for any launch accident. This system is also adaptable for electric propulsion or life-support during transit to and from Mars.
Date: November 9, 1998
Creator: Harms, G.A.; Lenard, R.X.; Lipinski, R.J. & Wright, S.A.
Partner: UNT Libraries Government Documents Department

An assessment of space reactor technology needs and recommendations for development

Description: In order to provide a strategy for space reactor technology development, the Defense Nuclear Agency (DNA) has authorized a brief review of potential national needs that may be addressed by space reactor systems. a systematic approach was used to explore needs at several levels that are increasingly specific. Level 0 -- general trends and issues; Level 1 -- generic space capabilities to address trends; Level 2 -- requirements to support capabilities; Level 3 -- system types capable of meeting requirements; Level 4 --generic reactor system types; and Level 5 -- specific baseline systems. Using these findings, a strategy was developed to support important space reactor technologies within a limited budget. A preliminary evaluation identified key technical issues and provide a prioritized set of candidate research projects. The evaluation of issues and the recommended research projects are presented in a companion paper.
Date: November 1, 1995
Creator: Marshall, A.C. & Wiley, R.L.
Partner: UNT Libraries Government Documents Department

Welding and Weldability of Thorium-Doped Iridium Alloys

Description: Ir-0.3%W alloys doped with thorium are currently used as post-impact containment material for radioactive fuel in thermoelectric generators that provide stable electrical power for a variety of outer planetary space exploration missions. Welding and weldability of a series of alloys was investigated using arc and laser welding processes. Some of these alloys are prone to severe hot-cracking during welding. Weldability of these alloys was characterized using Sigmajig weldability test. Hot-cracking is influenced to a great extent by the fusion zone microstructure and composition. Thorium content and welding atmosphere were found to be very critical. The weld cracking behavior in these alloys can be controlled by modifying the fusion zone microstructure. Fusion zone microstructure was found to be controlled by welding process, process parameters, and the weld pool shape.
Date: March 12, 2000
Creator: David, S.A.; Ohriner, E.K. & King, J.F.
Partner: UNT Libraries Government Documents Department

Characteristics of a Mixed Thorium-Uranium Dioxide High-Burnup Fuel

Description: Future nuclear fuels must satisfy three sets of requirements: longer times between refueling; concerns for weapons proliferation; and development of a spent fuel form more suitable for direct geologic disposal. This project has investigated a fuel consisting of mixed thorium and uranium dioxide to satisfy these requirements. Results using the SCALE 4.3 code system indicated that the mixed Th-U fuel could be burned to 72 MWD/kg or 100 MWD/kg using 25% of 35% UO2 respectively. The uranium remained below 20% total fissile fraction throughout the cycle, making it unusable for weapons. Total plutonium production per MWD was a factor of 4.5 less in the Th-U fuel than in the conventional fuel; Pu-239 production per MWD was a factor of 6.5 less; and the plutonium produced was high in Pu-238, leading to a decay heat 5 times greater than that from plutonium derived from conventional fuel and 40 times greater than weapons grade plutonium. High decay heat would require active cooling of any crude weapon, lest the components surrounding the plutonium be melted. Spontaneous neutron production for plutonium from Th-U fuel was 2.3 times greater than that from conventional fuel and 15 times greater than that from weapons grade plutonium. High spontaneous neutron production drastically limits the probable yield of a crude weapon. Because ThO2 is the highest oxide of thorium, while UO2 can be oxidized further to U3O8, ThO2-UO2 fuel may be a superior wasteform if the spent fuel is ever to be exposed to oxygenated water. Even if the cost of fabricating the mixed Th-U fuel is $100/kg greater, the cost of the Th-U fuel is 13% to 15% less than that of the fuels using uranium only.
Date: June 1, 1999
Creator: Herring, J. S. & MacDonald, P. E.
Partner: UNT Libraries Government Documents Department

GPHS-RTGs in support of the Cassini Mission. Semi-annual technical progress report, April 3, 1995--October 1, 1995

Description: This document is the April-October 1995 Progress Report on the Cassini RTG Program. Nine tasks are summarized; (1) Spacecraft integration and liason, (2) Engineering support, (3) Safety, (4) Unicouple fabrication, (5) ETG fabrication, assembly, and test, (6) Ground support equipment, (7) RTG shipping and launch support, (8) Design, reviews, and mission applications, and (9) Project management, QA, contract changes, and material acquisitions.
Date: October 24, 1995
Partner: UNT Libraries Government Documents Department

A bimodal spacecraft bus based on a cermet fueled heat pipe reactor

Description: Bimodal space reactor systems provide both thermal propulsion for the spacecraft orbital transfer and electrical power to the spacecraft bus once it is on station. These systems have the potential to increase both the available payload in high energy orbits and the available power to that payload. These increased mass and power capabilities can be used to either reduce mission cost by permitting the use of smaller launch vehicles or to provide increased mission performance from the current launch vehicle. A major barrier to the deployment of these bimodal systems has been the cost associated with their development. This paper describes a bimodal spacecraft bus with performance potential to permit more than 70% of the instrumented payload of the Titan IV/Centaur to be launched from the Atlas IIAS. The development cost is minimized by basing the design on existing component technologies.
Date: July 1995
Creator: Polansky, G. F.; Rochow, R. F.; Gunther, N. G. & Bixler, C. H.
Partner: UNT Libraries Government Documents Department

Superconducting thermoelectric generator

Description: This invention is comprised of an apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a higher thermal conductivity than that of the superconducting material. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials, establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.
Date: December 31, 1992
Creator: Metzger, J.D. & El-Genk, M.
Partner: UNT Libraries Government Documents Department

Heatpipe space power and propulsion systems

Description: Safe, reliable, low-mass space power and propulsion systems could have numerous civilian and military applications. This paper discusses two fission-powered concepts: The Heatpipe Power System (HPS), which provides power only; and the Heatpipe Bimodal System (HBS), which provides both power and thermal propulsion. Both concepts have 10 important features. First, only existing technology and recently tested fuel forms are used. Second, fuel can be removed whenever desired, which greatly facilitates system fabrication and handling. Third, full electrically heated system testing of all modes is possible, with minimal operations required to replace the heaters with fuel and to ready the system for launch. Fourth, the systems are passively subcritical during launch accidents. Fifth, a modular approach is used, and most technical issues can be resolved with inexpensive module tests. Sixth, bonds between dissimilar metals are minimized. Seventh, there are no single-point failures during power mode operation. Eighth, the fuel burnup rate is quite low to help ensure >10-yr system life. Ninth, there are no pumped coolant loops, and the systems can be shut down and restarted without coolant freeze/thaw concerns. Finally, full ground nuclear test is not needed, and development costs will be low. One design for a low-power HPS uses SNAP-10A-style thermoelectric power converters to produce 5 kWe at a system mass of {approximately}500 kg. The unicouple thermoelectric converters have a hot-shoe temperature of 1275 K and reject waste heat at 775 K. This type of thermoelectric converter has been used extensively by the space program and has demonstrated an operational lifetime of decades. A core with a larger number of smaller modules (same overall size) can be used to provide up to 500 kWt to a power conversion subsystem, and a slightly larger core using a higher heatpipe to fuel ratio can provide >1 MWt.
Date: December 1, 1995
Creator: Houts, M.G.; Poston, D.I. & Ranken, W.A.
Partner: UNT Libraries Government Documents Department

Application of GIS for Cassini Launch Support

Description: The Cassini spacecraft began its eleven-year mission to Saturn on October 15, 1997. The spacecraft is powered by Radioisotope Thermoelectric Generators and Light Weight Radioisotope Heating Units comprised primarily of plutonium-238 as fuel. Due to the potential for a radiation release in the event of a launch accident, the US Department of Energy deployed a contingency response team to Cape Canaveral to support the National Aeronautics and Space Administration for the Cassini launch. The team was comprised of radiation monitoring and assessment teams, a communications/logistics team, and a team of Field Analysis System for Emergency Response (FASER) Geographic Information System personnel. FASER is a system developed around Arc/Info and Arcview for integrating and analyzing spatial information for nuclear emergency response activities. FASER operators integrated data from radiological prediction models, background radiation measurements, and a global positioning system-based Flight Path Recovery System for monitoring real-time aircraft locations. With this system, spatial data met the need to be processed and presented to mission managers quickly during the hours preceding launch.
Date: August 1, 1998
Creator: Guber, A.L.
Partner: UNT Libraries Government Documents Department

A preliminary investigation of the Topaz II reactor as a lunar surface power supply

Description: Reactor power supplies offer many attractive characteristics for lunar surface applications. The Topaz II reactor resulted from an extensive development program in the former Soviet Union. Flight quality reactor units remain from this program and are currently under evaluation in the United States. This paper examines the potential for applying the Topaz II, originally developed to provide spacecraft power, as a lunar surface power supply.
Date: December 31, 1995
Creator: Polansky, G.F. & Houts, M.G.
Partner: UNT Libraries Government Documents Department

Recommendations for space reactor R&D tasks

Description: A rationale was developed to determine which technologies a space nuclear reactor technology based program pursue based on the fact that budgets would be limited. A preliminary evaluation was conducted to identify key technical issues and to recommend a prioritized set of candidate research projects that could be undertaken as part of the Defense Nuclear Agency (DNA) program in the near term. The recommendations made have not been adopted formally by the DNA`s Topaz International Program process. (TIP), but serve as inputs to the program plannin process.
Date: December 1, 1995
Creator: Wiley, R.L. & Marshall, A.C.
Partner: UNT Libraries Government Documents Department

A document review to characterize Atomic International SNAP fuels shipped to INEL 1966--1973

Description: This report provides the results of a document search and review study to obtain information on the spent fuels for the following six Nuclear Auxiliary Power (SNAP) reactor cores now stored at the Idaho National Engineering Laboratory (INEL): SNAP-2 Experimental Reactor, SNAP-2 Development Reactor, SNAP-10A Ground Test Reactor, SNAP-8 Experimental Reactor, SNAP-8 Development Reactor, and Shield Test Reactor. The report also covers documentation on SNAP fuel materials from four in-pile materials tests: NAA-82-1, NAA-115-2, NAA-117-1, and NAA-121. Pieces of these fuel materials are also stored at INEL as part of the SNAP fuel shipments.
Date: September 1, 1995
Creator: Wahnschaffe, S.D.; Lords, R.E.; Kneff, D.W.; Nagel, W.E.; Pearlman, H. & Schaubert, V.J.
Partner: UNT Libraries Government Documents Department

Comment on "Indication from Pioneer 10/11, Galileo, and Ulysses Data, of an Apparent Anomalous, Weak, Long-Range Acceleration"

Description: In a recent Letter Anderson et al. report some very intriguing radio observations flom various interplanetary spaceprobes over the past 18 years. They interpret this data as an anomalous deceleration of the spaceprobes. Here I offer a different interpretation: that the anomaly is related to the cosmological red shift.
Date: October 27, 1998
Creator: Humphreys, D.R.
Partner: UNT Libraries Government Documents Department

Radiological effluents released from nuclear rocket and ramjet engine tests at the Nevada Test Site 1959 through 1969: Fact Book

Description: Nuclear rocket and ramjet engine tests were conducted on the Nevada Test Site (NTS) in Area 25 and Area 26, about 80 miles northwest of Las Vegas, Nevada, from July 1959 through September 1969. This document presents a brief history of the nuclear rocket engine tests, information on the off-site radiological monitoring, and descriptions of the tests.
Date: June 1, 1995
Creator: Friesen, H.N.
Partner: UNT Libraries Government Documents Department

Effluent Containment System for space thermal nuclear propulsion ground test facilities

Description: This report presents the research and development study work performed for the Space Reactor Power System Division of the U.S. Department of Energy on an innovative ECS that would be used during ground testing of a space nuclear thermal rocket engine. A significant portion of the ground test facilities for a space nuclear thermal propulsion engine are the effluent treatment and containment systems. The proposed ECS configuration developed recycles all engine coolant media and does not impact the environment by venting radioactive material. All coolant media, hydrogen and water, are collected, treated for removal of radioactive particulates, and recycled for use in subsequent tests until the end of the facility life. Radioactive materials removed by the treatment systems are recovered, stored for decay of short-lived isotopes, or packaged for disposal as waste. At the end of the useful life, the facility will be decontaminated and dismantled for disposal.
Date: August 1, 1995
Partner: UNT Libraries Government Documents Department

Plutonium dioxide storage: Conditions for preparation and handling

Description: Desorption and adsorption of plutonium dioxide are derived from production-scale experiments that demonstrate techniques of preparing weapons-grade material for extended storage. In combination with data from literature, results define conditions for preparing and certifying PuO{sub 2} and provide essential information for developing and implementing a repackaging process compliant with DOE standards for safe storage of plutonium. As demonstrated by loss-on-ignition (LOI) analysis, adsorbates are effectively removed by heating the oxide in air at 950 C for two hours. After oxides are fired at this temperature, specific surface areas are consistently less than 5 m{sup 2}/g. Due to this low surface area, water adsorption by fired oxide is limited to a maximum of 0.2 mass % at 50% relative humidity. Kinetic data for the adsorption process show that water is accommodated on the oxide surface by a sequence of distinct first-order steps comprising five types of adsorbate interaction and accumulating ten molecular layers of H{sub 2}0 at 100% humidity. An equation defining the humidity dependence of the adsorption rate during the first step is applied in estimating time periods that a fired oxide may remain in given configurations without detrimental adsorption. Particle size measurements show that the source terms for environmental dispersal of oxides prepared by hydride-catalyzed reaction of metal and by oxalate calcination are approximately 20 and 0.1 mass %, respectively, and that the values are reduced by firing. Evidence for a chemical reaction between dioxide and water is discussed and practical applications of the results to oxide stabilization and LOI analysis are presented.
Date: August 1, 1995
Creator: Haschke, J.M. & Ricketts, T.E.
Partner: UNT Libraries Government Documents Department

On-Orbit Asset Management System, September 1995. Final report

Description: Declining budgets have prompted the need to decrease launch cost, increase satellite lifetime, and accomplish more with each satellite. This study evaluates an OOAMS system for its ability to lengthen lifetime of on-orbit assets, decrease the number of satellites required to perform a mission, increase responsiveness, and provide increased mission capability/tactical advantage. Lifetime analysis suggest that the larger satellite systems (NASA and military communication systems, surveillance satellites and earth observing satellites) would benefit most from a nuclear bimodal OOAMS. Evaluation of satellite constellations indicate that a modest reduction in the number of satellites could be realized using OOAMS if the thermal restart capability was at least ten. An OOAMS could improve the responsiveness (launching of new assets) using on-orbit reconstitution of assets. A top level utility assessment was done to address system cost issues relating to funding profiles, first unit cost, and break-even analysis. From mission capture and orbital lifetime criteria, the recommended minimum orbital altitude is 900 km. The on-orbit thermal restart capability should be increased from five to ten. Analysis of total impulse vs propellant consumed for selected missions suggests that total impulse be increased from 40 million to 48 million Newton-seconds.
Date: October 10, 1995
Partner: UNT Libraries Government Documents Department

Dose rate visualization of radioisotope thermoelectric generators

Description: Advanced visualization techniques can be used to investigate gamma ray and neutron dose rates around complex dose rate intensive operations. A method has been developed where thousands of dose points are calculated using the MCNP(Monte Carlo N-Particle) computer code and then displayed to create color contour plots of the dose rate for complex geometries. Once these contour plots are created, they are sequenced together creating an animation to dynamically show how the dose rate changes with changes in the geometry or source over time.
Date: September 1, 1995
Creator: Schwarz, R.A.; Kessler, S.F. & Tomaszewski, T.A.
Partner: UNT Libraries Government Documents Department

An overview of the Radioisotope Thermoelectric Generator Transporation System Program

Description: Radioisotope Thermoelectric Generators (RTG) convert the heat generated by radioactive decay to electricity using thermocouples. RTGs have a long operating life, are reasonably lightweight, and require little or no maintenance once assembled and tested. These factors make RTGs particularly attractive for use in spacecraft However, because RTGs contain significant quantities of radioactive materials, normally plutonium-238 and its decay products, they must be transported in packages built in accordance with Title 10, Code of Federal Regulations, Part 71. The US Department of Energy assigned the Radioisotope Thermoelectric Generator Transportation System (RTGTS) Program to Westinghouse Hanford Company in 1988 to develop a system meeting the regulatory requirements. The program objective was to develop a transportation system that would fully comply with 10 CFR 71 while protecting RTGs from adverse environmental conditions during normal conditions of transport (e.g., shock and heat). The RTGTS is scheduled for completion in December 1996 and will be available to support the National Aeronautics and Space Administrations Cassini mission to Saturn in October 1997. This paper provides an overview of the RTGTS and discusses the hardware being produced. Additionally, various program management innovations mandated by recent ma or changes in the US Department of Energy structure and resources will be outlined.
Date: October 1, 1995
Creator: McCoy, J.C.
Partner: UNT Libraries Government Documents Department

High temperature materials technology research for advanced thermionic systems. Quarterly progress report, March 1, 1995--June 30, 1995

Description: The concept of shift factor was used successfully to develop a model which described the role of solid solution atoms in dispersion strengthened tungsten alloys. This shift factor separates the solid solution strengthening effect of Re in the creep of W-Re-HfC materials. The creep of the alloys is expressed by the modified Lagneborg`s creep model in the following form: {dot {var_epsilon}} = A`(b/G{sup 3}kT)D{sub L}exp({minus} 580000eC{sup 1/2}/T)({sigma} {minus}{sigma}{sub p}){sup 4} (1955 K{le}T{le}2500 K), where D{sub L} is the lattice diffusion coefficient of tungsten.
Date: December 1, 1995
Creator: Zee, R.H. & Rose, M.F.
Partner: UNT Libraries Government Documents Department

Nuclear and thermal analysis of the heatpipe power and bimodal systems

Description: This paper discusses the nuclear and thermal analysis of two fission-powered concepts: (1)the Heatpipe Power System(HBS), which provides which provides power only, and (2) the Heatpipe Bimodal System (HBS), which provides both power and thermal propulsion. The HPS and HBS systems can provide substantial levels of power and propulsion at low mass with a high degree of safety and reliability. The systems have been designed to utilize existing technology and facilities, which will make the development cost relatively low.
Date: December 1, 1995
Creator: Poston, D.I. & Houts, M.G.
Partner: UNT Libraries Government Documents Department

Review of DOE criteria for safe storage of Pu metals and oxides.

Description: A technical review of the DOE criteria for storage of plutonium metals and oxides determined the maximum pressure that could be obtained from 50-year storage of 5.0-kg of PuO{sub 2} powder under the assumed worst-case conditions derived from the DOE standard [1,2]. Those conditions included a final temperature of 400 F and the reaction to yield H{sub 2} gas in accordance with the equation PuO{sub 2}(c) + x H{sub 2}O {r_arrow} PuO{sub 2+x}(c) + x H{sub 2}(g) where the x moles of sorbed water represents 0.5 wt.% of the PuO{sub 2}. The worst-case conditions also included the generation of He gas from the 50-year {alpha}-decay of the plutonium, that was considered to be power grade plutonium with the maximum limit of 3% for the short-lived isotope, Pu-238. The free volume for containment of the gases generated in the primary containment vessel, assuming failure of its inner boundary container, was assumed to be 2.5-L value given in the original standard.
Date: April 22, 1998
Creator: Rothman, A. B.
Partner: UNT Libraries Government Documents Department