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Development of improved thermoelectric materials for space nuclear power systems. Sixth technical progress report, March 1985

Description: The program consists of two main tasks encompassing (1) the development of an improved SiGe alloy and (2) the development of an as yet unspecified advanced material intended to have superior performance characteristics when compared to SiGe alloys. Significant progress was made toward the goal of producing a SiGe based material with an improved figure-of-merit during this reporting period. In these studies, a quantitative evaluation of the characteristics which produce the low thermal conductivities observed in SiGe alloys is being developed. Specific areas of emphasis include the effects of grain size, charge carrier and GaP concentrations. An alternate method for alloying with GaP was evaluated in which the GaP was added to SiGe during the melting operation.
Date: January 1, 1985
Partner: UNT Libraries Government Documents Department

Chemical thermodynamic assessment of the Li-U-O system for possible space nuclear applications

Description: A thermochemical assessment of possible oxide fuel-lithium coolant interactions in conceptual 100-kW(e) space nuclear power reactors has been performed. Results of the evaluation indicate that in the event of a cladding breach the fuel and coolant will interact with extremely negative consequences. The lithium has the potential to reduce the fuel to metallic uranium. Differences in temperature within the coolant loop can drive oxygen and uranium transport processes.
Date: June 1, 1985
Creator: Besmann, T.M. & Cooper, R.H. Jr.
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

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

Development and characterization of carbon-bonded carbon fiber insulation for radioisotope space power systems

Description: The General-Purpose Heat Source (GPHS), an improved radioisotope heat source, employs a unique thermal insulation material, carbon-bonded carbon fiber (CBCF), to protect the fuel capsule and to help achieve the highest possible specific power. The CBCF insulation is made from chopped rayon fiber about 10 ..mu..m in diameter and 250 ..mu..m long, which is carbonized and bonded with phenolic resin particles. The CBCF shapes, both tubes and plates, are formed in a multiple molding facility by vacuum molding a water slurry of the carbonized chopped-rayon fiber (54 wt %) and phenolic resin (46 wt %). The molded shapes are subsequently dried and cured. Final carbonization of the resin is at 1600/sup 0/C. Machining to close tolerances (+-0.08 mm) is accomplished by conventional tooling and fixturing. The resulting material is an excellent lightweight insulation with a nominal density of 0.2 Mg/m/sup 3/ and a thermal conductivity of 0.24 W(m.K) in vacuum at 2000/sup 0/C. Several attributes that make CBCF superior to other known high-temperature insulation materials for the GPHS application have been identified. It has the excellent attributes of light weight, low thermal conductivity, chemical compatibility, and high-temperature capabilities. The mechanical strength of CBCF insulation is satisfactory for the GPHS application; it has passed vibration tests simulating launch conditions. The basic fabrication technique was refined to eliminate undesirable large pores and cracks often present in materials fabricated by earlier techniques. Also, processing was scaled up to incease the fabrication rate by a factor of 10. The specific properties of the CBCF were tailored by adjusting material and processing variables to obtain the desired results. We report here how work on CBCF characterization and development conducted at ORNL from 1978 through 1980 has contributed to the GPHS program to meet the requirements of both the Galileo and Ulysees Missions.
Date: June 1, 1985
Creator: Wei, G.C. & Robbins, J.M.
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

Cermet fuels for space power systems

Description: A refractory-metal matrix, UN-fueled cermet is a very promising fuel candidate for a wide range of multi-megawatt space reactor systems, e.g., steady-state, flexible duty-cycle, or bimodal, single- or two-phase liquid-metal cooled reactors, or thermionic reactors (Coomes et al. 1986, Takkuhen 1969, Unpublished ANL). Cermet fuel is especially promising for reactor designs that require operational strategies which incorporate rapid power changes because of its anticipated capability to withstand thermal shock.
Date: November 1, 1985
Creator: Barner, J.O.; Coomes, E.P.; Williford, R.E. & Neimark, L.A.
Partner: UNT Libraries Government Documents Department

SPR-8 multi-mega watt space power system (MMW-SPS) concept description and concept refinement plan

Description: The SPR-8 MMW-SPS concept can satisfy both continuous and burst mode power requirements. At 10 MWe continuous mode power for 5 yr and 75 MWe burst mode power for 200 sec, the SPR-8 concept can power radar systems for detecting ballistic missile launchings and for discriminating between warheads and decoys. When enemy action is detected the SPR-8 MMW-SPS can power a rail gun, free electron laser, or particle beam and destroy the missile in the boost phase or warheads in space flight. The SPR-8 concept is based on the SPR-6 system (ref. 1) for providing continuous mode power. The system uses a fast UN-fueled, lithium-cooled reactor. Heat is transferred from the lithium coolant to potassium in a shell and tube heat exchanger-boiler. Potassium vapor is expanded through a turbine in a saturated Rankine cycle. After passing through the turbine the potassium is condensed in a compact heat exchanger by transferring heat to the radiator working fluid. An advanced radiator design is envisioned. Much work will be required in radiator technology to achieve low mass and plan form. For completeness of the SPR-8 system concept, a charged liquid droplet radiator is assumed but other types should be considered. Mechanical pumps are used for simplicity, but other types should be considered. A block diagram of the SPR-8 system is given.
Date: April 15, 1985
Creator: Walter, C.E.
Partner: UNT Libraries Government Documents Department

Commercial Nuclear Waste Research and Development Program. Quarterly report, April-June 1985

Description: Support was provided to DOE/NV during preparation of a proposal, requested by the DOE San Francisco office, for performance of SP-100 Ground Engineering Systems tests at the E-MAD facility. The site selection committee visited the Nevada Test Site in May for a tour and briefings on all aspects of the proposal. The fuel assembly used in the two-year metal cask simulation test was removed from the test stand and characterized to document its post-test condition. Fuel assembly integrity monitoring for the second half of FY 1985 was completed of six of the fuel assemblies being stored in unwelded canisters. Post-storage characterization was completed on three fuel assemblies which were stored in welded canisters. All test procedures have been completed and delivered for the Canister Assembly Launch Test Program being conducted at another Area 25 facility. The "Safety Assessment Document for Spent Fuel Handling, Packaging, and Storage Demonstrations at the E-MAD Facility on the Nevada Test Site," DOE/NV10250-20, was revised to be consistent with new and revised DOE Orders and Directives, and delivered to DOE/NV.
Date: July 1985
Partner: UNT Libraries Government Documents Department

Light-Weight Radioisotope Heater Unit Safety Analysis Report (LWRHU-SAR). Volume I. A. Introduction and executive summary. B. Reference Design Document (RDD)

Description: The orbiter and probe portions of the NASA Galileo spacecraft contain components which require auxiliary heat during the mission. To meet these needs, the Department of Energy's (DOE's) Office of Special Nuclear Projects (OSNP) has sponsored the design, fabrication, and testing of a one-watt encapsulated plutonium dioxide-fueled thermal heater named the Light-Weight Radioisotope Heater Unit (LWRHU). This report addresses the radiological risks which might be encountered by people both at the launch area and worldwide should postulate mission failures or malfunctions occur, which would result in the release of the LWRHUs to the environment. Included are data from the design, mission descriptions, postulated accidents with their consequences, test data, and the derived source terms and personnel exposures for the various events.
Date: October 1, 1985
Creator: Johnson, E.W.
Partner: UNT Libraries Government Documents Department

Tethered nuclear power for the Space Station

Description: A nuclear space power system the SP-100 is being developed for future missions where large amounts of electrical power will be required. Although it is primarily intended for unmanned spacecraft, it can be adapted to a manned space platform by tethering it above the station through an electrical transmission line which isolates the reactor far away from the inhabited platform and conveys its power back to where it is needed. The transmission line, used in conjunction with an instrument rate shield, attenuates reactor radiation in the vicinity of the space station to less than one-one hundredth of the natural background which is already there. This combination of shielding and distance attenuation is less than one-tenth the mass of boom-mounted or onboard man-rated shields that are required when the reactor is mounted nearby. This paper describes how connection is made to the platform (configuration, operational requirements) and introduces a new element the coaxial transmission tube which enables efficient transmission of electrical power through long tethers in space. Design methodology for transmission tubes and tube arrays is discussed. An example conceptual design is presented that shows SP-100 at three power levels 100 kWe, 300 kWe, and 1000 kWe connected to space station via a 2 km HVDC transmission line/tether. Power system performance, mass, and radiation hazard are estimated with impacts on space station architecture and operation.
Date: January 1, 1985
Creator: Bents, D.J.
Partner: UNT Libraries Government Documents Department

Testimony (on space nuclear power) before the Subcommittee on Energy Research and Production of the Committee on Science and Technology, US House of Representatives

Description: This brief presentation consists of four parts: first, a few introductory comments about space nuclear power technology; second, a description of activities currently underway at Martin Marietta Energy Systems; third, a discussion of future directions at Martin Marietta Energy Systems; and fourth, some recommendations.
Date: October 9, 1985
Creator: Mynatt, F.R.
Partner: UNT Libraries Government Documents Department

SP-100 low mass shield design

Description: The shielding considerations for an unmanned space reactor system are somewhat different from those for a terrestrial reactor. An unmanned operation in space implies that only a shadow shield, rather than a 4..pi.. one, is required to protect payload hardware that typically can tolerate 10/sup 4/ to 10/sup 6/ times more radiation than can a human crew. On the other hand, the system mass, of which the radiation shield can be a significant fraction, is a severe constraint for space reactors and not normally a problem with terrestrial ones. The object of this paper is to briefly summarize advancements made on various aspects of low mass shield design for space reactors, including materials and their arrangements, geometric factors and their potential impact on system design optimization, and proposed new configuration concepts for further mass reduction.
Date: January 1, 1985
Creator: Carlson, D.E.
Partner: UNT Libraries Government Documents Department

Transient heat pipe investigations for space power systems

Description: A 4-meter long, high temperature, high power, molybdenum-lithium heat pipe has been fabricated and tested in transient and steady state operation at temperatures to 1500 K. Maximum power throughput during the tests was approximately 37 kW/cm/sup 2/ for the 1.4 cm diameter vapor space of the annular wick heat pipe. The evaporator flux density for the tests was 150.0 W/cm/sup 2/ over a length of 40 cm. Condenser length was approximately 3.0 m with radiant heat rejection from the condenser to a coaxial, water cooled radiation calorimeter. A variable radiation shield, controllable from the outside of the vacuum enclosure, was used to vary the load on the heat pipe during the tests. 1 ref., 9 figs.
Date: January 1, 1985
Creator: Merrigan, M.A.; Keddy, E.S. & Sena, J.T.
Partner: UNT Libraries Government Documents Department

Environmental safety analysis tests on the Light Weight Radioisotope Heater Unit (LWRHU)

Description: A series of safety tests has been performed on the Light Weight Radioisotope Heater Unit (LWRHU), a /sup 238/PuO/sub 2/-fueled device designed to provide thermal energy at selected locations in a spacecraft. The tests simulate the thermal and mechanical environments postulated for spacecraft accidents on the launch pad and on reentry abort. The tests demonstrate almost complete containment of the fuel, or fuel simulant (depleted UO/sub 2/), in (1) an overpressure environment of 12.76 MPa (1850 psi), (2) on impact by an 18-g aluminum fuel-tank fragment at velocities greater than 750 m/s (2460 ft/s) but less than 900 m/s (2950 ft/s), (3) during a 10.5-min burn of a 0.9 x 0.9 x 0.9 m (3 x 3 x 3 ft) block of solid rocket motor propellant, (4) after impact at 49 m/s (161 ft/s) in four different orientations on a hard surface, and (5) during immersion in seawater for 1.75 years at both sea level pressure and at a pressure equivalent to 6000 m (19,700 ft) of ocean depth.
Date: May 1, 1985
Creator: Tate, R.E. & Land, C.C.
Partner: UNT Libraries Government Documents Department

Long-term exposure of /sup 238/PuO/sub 2/ to a terrestrial environment. Volume III

Description: A plutonium oxide source consisting of a single piece of 83% /sup 238/PuO/sub 2/ and weighing 38 g was exposed for 2.9 years to a humid, temperate terrestrial environment in an environmental simulation chamber. The soil tray of the chamber was divided into four compartments so that different soil types could be studied under identical conditions. Soils examined in this experiment included loam, silt loam, sand, and humus. Plutonium released into the soils, the soil drainages, and the condensates from the dehumidifier was monitored throughout the experiment. The total plutonium release rate from the PuO/sub 2/ source was approximately 2 ng/m/sup 2//s. The generation of short-ranged airborne plutonium, able to travel from a few centimeters to half a meter, was one of the most significant release pathways. The amount of plutonium released in this way was 10 times that washed directly off the source by rainwater and 20 times that from the fully airborne (longer ranged) release. Of the 200 ..mu..g of plutonium deposited in the soils, less than 0.1 ..mu..g was released into the soil percolates. In fact, the soil percolates constituted the least significant release pathway. Within the uncertainties in deriving the plutonium inventories of the soil compartments, we found no discernible differences among the behaviors of the four soil types towards plutonium. There was little or no seasonal effect on the release of plutonium from the soil.
Date: February 1, 1985
Creator: Heaton, R.C.; Patterson, J.H.; Steinkruger, F.J. & Coffelt, K.P.
Partner: UNT Libraries Government Documents Department

Design of a Pu-238 waste incineration process

Description: Combustible /sup 238/Pu waste is generated as a result of normal operation and decommissioning activity at the Savannah River Plant and is being retrievably stored at the Plant. As part of the long-term plan to process the stored waste and current waste in preparation for future disposition, a /sup 238/Pu incinceration process is being cold-tested at SRL. The incineration process consists of a continuous-feed preparation system, a two-stage, electrically fired incinerator, and a filtration off-gas system. Process equipment has been designed, fabricated, and installed for nonradioactive testing and cold run-in. Design features to maximize the ability to remotely maintain the equipment were incorporated into the process. Interlock, alarm, and control functions are provided by a programmable controller. Cold testing is scheduled to be completed in 1986.
Date: January 1, 1985
Creator: Charlesworth, D.L. & McCampbell, R.B.
Partner: UNT Libraries Government Documents Department

Savannah River Laboratory monthly report

Description: Efforts in the area of nuclear reactors and scientific computations are reported, including: robotics; reactor irradiation of nonend-bonded target slugs; computer link with Los Alamos National Laboratory; L-reactor thermal mitigation; aging of carbon in SRP reactor airborne activity confinement systems; and reactor risk assessment for earthquakes. Activities in chemical processes and environmental technology are reported, including: solids formation in a plutonium product stream; revised safety analysis reporting for F and H-Canyon operations; organic carbon analysis of DWPF samples; applications of Fourier transform infrared spectrometry; water chemistry analyzer for SRP reactors; and study of a biological community in Par Pond. Defense waste and laboratory operations activities include: Pu-238 waste incinerator startup; experimental canister frit blaster; saltstone disposal area design; powder metallurgy core diameter measurement; and a new maintenance shop facility. Nuclear materials planning encompasses decontamination and decommissioning of SRP facilities and a comprehensive compilation of environmental and nuclear safety issues. (LEW)
Date: December 1, 1985
Partner: UNT Libraries Government Documents Department

Space reactor ground tests, assessment of facility needs

Description: This paper discusses facility requirements for previously-specified, space-reactor ground tests of operating reactor prototypes. The paper also discusses engineering development tests applicable to fully-integrated space reactors and their subsystems. The development tests were derived by considering the functions and environments that the reactor might encounter in normal or abnormal launch-to-recovery sequences. Surety (safety, safeguards, and reliability) priorities will influence the final character of both the test program and the facilities requirements. Sandia facilities suitable for conducting the above tests are the main focus of this paper.
Date: January 1, 1985
Creator: Philbin, J.S. & Wemple, R.P.
Partner: UNT Libraries Government Documents Department

Liquid metal thermoelectric converter (LMTEC) for solar applications

Description: An overview is given of the research and development plan for the Liquid Metal Thermoelectric Converter (LMTEC) being undertaken by Sandia Laboratories under the Solar Thermal Technologies program of DOE. Sandia initiated work in this area less than a year ago and has pursued the work as a specific subtask starting in FY 1985. As with any new project, a significant part of the initial effort has been spent on reviewing the current technology in thermo-electric converters including Thermally Regenerative Electrochemical Systems (TRES), fuel cells, thermionic devices, magnetohydrodynamics, and other modes of direct thermal-to-electric conversion. Consequently, no formal research results are included in this paper and the presentation is intended more to indicate those areas in which further research and development efforts could be expended to prove of positive impact on the solar application of LMTEC. The principal objective of this task is to design, engineer, and develop a LMTEC suitable for use in solar distributed receiver applications. Since the thermal requirements for the LMTEC are in the temperature range of parabolic dishes, the engineering development effort will concentrate on a device that can be mounted at the focal point of a dish and preferably incorporated into the receiver. Due to a technology review, the LMTEC most likely will be based on the current Sodium Heat Engine (SHE) concept. Our main effort will consist of optimizing the concept for solar applications and conducting the necessary engineering development to produce a 20 to 50 kWe device.
Date: January 1, 1985
Creator: Martinez, J.I.
Partner: UNT Libraries Government Documents Department

Analysis of alkali liquid metal Rankine space power systems

Description: Space power systems must have both high power density (kW/m/sup 3/) and high specific power output (kW/kg), while maintaining high reliability. Several power source and conversion options are available. A sketch of the Rankine system under consideration is shown. The design for the 100 kWe system analyzed here uses the same basic design concept as described by Jones for a 5 MWe system. In brief, it consists of a uranium nitride fuel pin reactor core with a tungsten/lithium hydride shield. Potassium at approx. 25% quality exits the reactor core. A separator is used to provide potassium vapor (at approx. 99%+ quality) to a full impulse turbine. Liquid from the separator is recirculated back to the core inlet using jet pumps. A heat pipe radiator condenses the vapor exiting the turbine while a separate turbine driven boiler feed pump returns the condensed liquid to the core inlet. Sizes and weights for the various system components were determined using design algorithms or were scaled from previous design studies.
Date: January 1, 1985
Creator: Yoder, G.L. & Graves, R.L.
Partner: UNT Libraries Government Documents Department