56 Matching Results

Search Results

Advanced search parameters have been applied.

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

High power density reactors based on direct cooled particle beds

Description: Reactors based on direct cooled HTGR type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out long the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBR's) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed. 12 figs.
Date: January 1, 1985
Creator: Powell, J.R. & Horn, F.L.
Partner: UNT Libraries Government Documents Department

Strategic defense initiative

Description: The Engineering Technology Division has a leading role, including that of program management, in a major new programmatic thrust of the Oak Ridge National Laboratory that is in support of the national Strategic Defense Initiative (SDI). It is appropriate for the Laboratory to become significantly involved in the program because several of the most promising SDI technologies are in areas for which ORNL (together with Y-12 and K-25) have strong capabilities and significant resources. The initial ORNL work in support of the SDI program is focused on three technologies in which ORNL has extensive experience and traditionally strong research and development programs: (1) space nuclear power, (2) flywheel energy storage, and (3) neutral particle beams. The space nuclear program will utilize our capabilities in areas such as refractory materials, high-temperature alkali metal systems, shielding, and instrumentation. Space nuclear reactors capable of supplying multimegawatt levels of electrical power on a continuous and long-term basis are envisioned to be required for a variety of SDI surveillance satellites and space-borne weapons platforms. The feasibility of an alkali metal Rankine power conversion cycle, which has promise of providing high power with a very low system mass, is planned for study.
Date: January 1, 1985
Creator: Nichols, J.P.
Partner: UNT Libraries Government Documents Department

Neutron flux, spectrum, and dose equivalent measurements for a 4500-W(th) /sup 238/PuO/sub 2/ general purpose heat source

Description: The total emission rate is (4.5 +- 0.4) 10/sup 7/ n/s, and the average neutron energy is (1.64 +- 0.07) MeV. The factor for converting from neutron fluence to dose equivalent for this spectrum is (3.10 +- 0.24) 10/sup -5/ mRem/n-cm/sup -2/. The factor for converting from neutron fluence to tissue absorbed dose is (3.18 +- 0.26) 10/sup -6/ mRad/n-cm/sup -2/.
Date: May 9, 1985
Creator: Anderson, M.E.
Partner: UNT Libraries Government Documents Department

PEGASUS: a multi-megawatt nuclear electric propulsion system

Description: With the Space Transportation System (STS), the advent of space station Columbus and the development of expertise at working in space that this will entail, the gateway is open to the final frontier. The exploration of this frontier is possible with state-of-the-art hydrogen/oxygen propulsion but would be greatly enhanced by the higher specific impulse of electric propulsion. This paper presents a concept that uses a multi-megawatt nuclear power plant to drive an electric propulsion system. The concept has been named PEGASUS, PowEr GenerAting System for Use in Space, and is intended as a ''work horse'' for general space transportation needs, both long- and short-haul missions. The recent efforts of the SP-100 program indicate that a power system capable of producing upwards of 1 megawatt of electric power should be available in the next decade. Additionally, efforts in other areas indicate that a power system with a constant power capability an order of magnitude greater could be available near the turn of the century. With the advances expected in megawatt-class space power systems, the high specific impulse propulsion systems must be reconsidered as potential propulsion systems. The power system is capable of meeting both the propulsion system and spacecraft power requirements.
Date: June 1, 1985
Creator: Coomes, E.P.; Cuta, J.M.; Webb, B.J. & King, D.Q.
Partner: UNT Libraries Government Documents Department

Regulatory analysis on emergency preparedness for fuel cycle and other radioactive material licensees. Draft report for comment

Description: Potential accidents for 15 types of fuel cycle and other radioactive material licensees were analyzed. The most potentially hazardous accident, by a large margin, was determined to be the sudden rupture of a heated multi-ton cylinder of UF/sub 6/. Acute fatalities offsite are probably not credible. Acute permanent injuries may be possible for many hundreds of meters, and clinically observable transient effects of unknown long term consequences may be possible for distances up to a few miles. These effects would be caused by the chemical toxicity of the UF/sub 6/. Radiation doses would not be significant. The most potentially hazardous accident due to radiation exposure was determined to be a large fire at certain facilities handling large quantities of alpha-emitting radionuclides (i.e., Po-210, Pu-238, Pu-239, Am-241, Cm-242, Cm-244) or radioiodines (I-125 and I-131). However, acute fatalities or injuries to people offsite due to accidental releases of these materials do not seem plausible. The only other significant accident was identified as a long-term pulsating criticality at fuel cycle facilities handling high-enriched uranium or plutonium. An important feature of the most serious accidents is that releases are likely to start without prior warning. The releases would usually end within about half an hour. Thus protective actions would have to be taken quickly to be effective. There is not likely to be enough time for dose projections, complicated decisionmaking during the accident, or the participation of personnel not in the immediate vicinity of the site. The appropriate response by the facility is to immediately notify local fire, police, and other emergency personnel and give them a brief predetermined message recommending protective actions. Emergency personnel are generally well qualified to respond effectively to small accidents of these types.
Date: June 1, 1985
Creator: McGuire, S.A.
Partner: UNT Libraries Government Documents Department

Feasibility of meltcasing strontium fluoride to produce high-density heat sources

Description: A modest proof-of-principle effort has been conducted to investigate melt casting as a process for compacting SrF/sub 2/ to near theoretical density. A nonradioactive SrF/sub 2/ mixture, similar in chemical composition and method of prepartion to SrF/sub 2/ encapsulated at the Hanford Waste Encapsulation and Storage Facility (WESF) was used for the test evaluations. Hard, dimensionally stable, monolithic ingots that are >98% of theoretical density have been produced. Significant chemical purification from Al, Fe, Cr, Ni, Na and Zr has been demonstrated.
Date: February 1, 1985
Creator: Wheelwright, E.J. & Montgomery, D.R.
Partner: UNT Libraries Government Documents Department

Current regulatory and licensing status for byproduct sources, facilities and applications

Description: Public use of nuclear byproducts, especially radioactive isotopes, will require approval by various regulatory agencies. Use of cesium-137 as an irradiation source for sterilizing medical products will require US Nuclear Regulatory Commission (NRC) approval. Two applications have been filed with NRC, and approval is expected soon. Widespread use of irradiation for food products depends on a favorable ruling by the Food and Drug Administration (FDA). A ruling is pending that would permit irradiation of fruits and vegetables up to 100 krad. NRC also controls the use of isotopes in remote power generators, but little regulatory action has been required in recent years. Recent development of radioluminescent (RL) lighting for runway lights has led to interest by commercial manufacturers. At the present time, a license has been issued to at least one manufacturer for sale of tritium-powered runway lights. 28 refs., 1 fig.
Date: February 1, 1985
Creator: Tingey, G.L.; Jensen, G.A. & Hazelton, R.F.
Partner: UNT Libraries Government Documents Department