46 Matching Results

Search Results

Advanced search parameters have been applied.

New vision solar system mission study. Final report

Description: The vision for the future of the planetary exploration program includes the capability to deliver {open_quotes}constellations{close_quotes} or {open_quotes}fleets{close_quotes} of microspacecraft to a planetary destination. These fleets will act in a coordinated manner to gather science data from a variety of locations on or around the target body, thus providing detailed, global coverage without requiring development of a single large, complex and costly spacecraft. Such constellations of spacecraft, coupled with advanced information processing and visualization techniques and high-rate communications, could provide the basis for development of a {open_quotes}virtual{close_quotes} {open_quotes}presence{close_quotes} in the solar system. A goal could be the near real-time delivery of planetary images and video to a wide variety of users in the general public and the science community. This will be a major step in making the solar system accessible to the public and will help make solar system exploration a part of the human experience on Earth.
Date: March 1, 1996
Creator: Mondt, J.F. & Zubrin, R.M.
Partner: UNT Libraries Government Documents Department

Development program to recycle and purify plutonium-238 oxide fuel from scrap

Description: Nuclear Materials Technology (NMT) Division has initiated a development program to recover and purify plutonium-238 oxide from impure sources. A glove box line has been designed and a process flowsheet developed to perform this task on a large scale. The initial effort has focused on purification of {sup 238}PuO{sub 2} fuel that fails to meet General Purpose Heat Source (GPHS) specifications because of impurities. The notable non-actinide impurities were silicon and phosphorus, but aluminum, chromium, iron and nickel were also near or in excess of limits specified by GPHS fuel powder specifications. Among actinide impurities, uranium is of paramount concern because {sup 234}U is the daughter of {sup 2238}Pu by alpha decay, and is the largest actinide impurity. An aqueous method based on nitric acid was selected for purification of the {sup 238}PuO{sub 2} fuel. All aqueous processing used high purity reagents, and was performed in PTFE apparatus to minimize introduction of new contaminants. Impure {sup 238}PuO{sub 2} was first dissolved in refluxing HNO{sub 3}/HF and then the solution was filtered. The dissolved {sup 238}Pu was adjusted to the trivalent state by an excess of reducing reagents to compensate for radiolytic effects, precipitated as plutonium(III) oxalate, and recovered by filtration. The plutonium(III) oxalate was subsequently calcined to convert the plutonium to the oxide. Decontamination factors for silicon, phosphorus and uranium were excellent. Decontamination factors for aluminum, chromium, iron and nickel were very good. The purity of the {sup 238}PuO{sub 2} recovered from this operation was significantly better than specifications. Efforts continue to develop the capability for efficient, safe, cost-effective, and environmentally acceptable methods to recover and purify {sup 238}PuO{sub 2} fuel in a glovebox environment. Plutonium-238 materials targeted for recovery includes impure oxide and scrap items that are lean in {sup 238}Pu values.
Date: December 1996
Creator: Schulte, L. D.; Silver, G. L.; Avens, L. R.; Jarvinen, G. D.; Espinoza, J.; Foltyn, E. M. et al.
Partner: UNT Libraries Government Documents Department

General-purpose heat source: Research and development program. Radioisotope thermoelectric generator impact tests: RTG-1 and RTG-2

Description: The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of {sup 238}Pu decay to an array of thermoelectric elements in a radioisotope thermoelectric generator (RTG). Because the potential for a launch abort or return from orbit exists for any space mission, the heat source response to credible accident scenarios is being evaluated. The first two RTG Impact Tests were designed to provide information on the response of a fully loaded RTG to end-on impact against a concrete target. The results of these tests indicated that at impact velocities up to 57 m/s the converter shell and internal components protect the GPHS capsules from excessive deformation. At higher velocities, some of the internal components of the RTG interact with the GPHS capsules to cause excessive localized deformation and failure.
Date: July 1, 1996
Creator: Reimus, M.A.H.; Hinckley, J.E. & George, T.G.
Partner: UNT Libraries Government Documents Department

[Radioisotope thermoelectric generators and ancillary activities]. Monthly technical progress report, 1 April--28 April 1996

Description: Tehnical progress achieved during this period on radioisotope thermoelectric generators is described under the following tasks: engineering support, safety analysis, qualified unicouple fabrication, ETG fabrication/assembly/test, RTG shipping/launch support, design/review/mission applications, and project management/quality assurance/reliability.
Date: June 1, 1996
Partner: UNT Libraries Government Documents Department

Monthly technical progress report, 29 January 1996--25 Februray 1996

Description: This report discusses the technical progress made on the radioisotope thermoelectric generators and ancillary activities for the Cassini space probe mission to the planet Saturn. The probe is designated for launch in October of 1997. This report covers the project reporting period from 29 January 1996 through 25 February 1996. The report is organized by program task structure and includes activities for: spacecraft integration and liason; engineering support; safety; qualified unicouple production; ETG fabrication, assembly, and testing; RTG shipping and launch support; designs, reviews and mission applications; quality assurance, reliability and contract changes; and CAGO acquisition.
Date: April 1, 1996
Partner: UNT Libraries Government Documents Department

Comparison of different pressing techniques for the preparation of n-type silicon-germanium thermoelectric alloys

Description: Improvements to state-of-the-art Si{sub 80}Ge{sub 20} thermoelectric alloys have been observed in laboratory-scale samples by the powder metallurgy techniques of mechanical alloying and hot pressing. Incorporating these improvements in large scale compacts for the production of thermoelectric generator elements is the next step in achieving higher efficiency RTGs. This paper discusses consolidation of large quantities of mechanically alloyed powders into production size compacts. Differences in thermoelectric properties are noted between the compacts prepared by the standard technique of hot uniaxial pressing and hot isostatic pressing. Most significant is the difference in carrier concentration between the alloys prepared by the two consolidation techniques.
Date: June 1, 1996
Creator: Harringa, J.L. & Cook, B.A.
Partner: UNT Libraries Government Documents Department

Cassini RTG Program. Monthly technical progress report, 27 November--31 December 1995

Description: This monthly technical progress report provided information on the following tasks: spacecraft integration and liaison; engineering support; safety analysis; qualified unicouple fabrication; ETG fabrication, assembly, and test; ground support equipment (GSE); RTG shipping and launch support; designs, reviews, and mission applications; project management, quality assurance, and reliability, and contractor acquired government owned (CAGO) property acquisition.
Date: January 24, 1996
Partner: UNT Libraries Government Documents Department

Developing high-performance cross-functional teams: Understanding motivations, functional loyalties, and teaming fundamentals

Description: Teamwork is the key to the future of effective technology management. Today`s technologies and markets have become too complex for individuals to work alone. Global competition, limited resources, cost consciousness, and time pressures have forced organizations and project managers to encourage teamwork. Many of these teams will be cross-functional teams that can draw on a multitude of talents and knowledge. To develop high-performing cross-functional teams, managers must understand motivations, functional loyalties, and the different backgrounds of the individual team members. To develop a better understanding of these issues, managers can learn from experience and from literature on teams and teaming concepts. When studying the literature to learn about cross-functional teaming, managers will find many good theoretical concepts, but when put into practice, these concepts have varying effects. This issue of varying effectiveness is what drives the research for this paper. The teaming concepts were studied to confirm or modify current understanding. The literature was compared with a {open_quotes}ground truth{close_quotes}, a survey of the reality of teaming practices, to examine the teaming concepts that the literature finds to be critical to the success of teams. These results are compared to existing teams to determine if such techniques apply in real-world cases.
Date: August 1, 1996
Creator: Miller, M.A.
Partner: UNT Libraries Government Documents Department

Nuclear source term evaluation for launch accident environments

Description: When United States space missions involve launching vehicles carrying significant quantities of nuclear material, US law requires that prior to launch the mission be approved by the Office of the President. This approval is to be based on an evaluation of the nuclear safety risks associated with the mission and the projected benefits. To assist in the technical evaluation of risks for each mission, an Interagency Nuclear Safety Review Panel (INSRP) is instituted to provide an independent assessment of the mission risks. INSRP`s assessment begins with a review of the safety analysis for the mission completed by the organization proposing the mission and documented in a Safety Analysis Report (SAR). In addition, INSRP may execute other analyses it deems necessary. Results are documented and passed to the decision maker in a Safety Evaluation Report (SER). The INSRP review and evaluation process has been described in some detail in a number of papers.
Date: May 1, 1996
Creator: McCulloch, W.H.
Partner: UNT Libraries Government Documents Department

General-purpose heat source: Research and development program. High-siliocon fuel characterization study: Half module impact tests 1 and 2

Description: The General-Purpose Heat Source (GPHS) provides power for space missions by transmitting the heat of {sup 238}Pu decay to an array of thermoelectric elements. Because any space mission could experience a launch abort or return from orbit, the heat source must be designed and constructed to survive credible accident environments. Previous testing conducted in support of the Galileo and Ulysses missions documented the response of GPHSs to a variety of fragment-impact, aging, atmospheric reentry, and earth-impact conditions. The evaluations documented in this report are part of an ongoing program to determine the effect of fuel impurities on the response of the heat source to conditions baselined during the Galileo/Ulysses test program. In the first two tests in this series, encapsulated GPHS fuel pellets containing high levels of silicon were aged, loaded into GPHS module halves, and impacted against steel plates. The results show no significant differences between the response of these capsules and the behavior of relatively low-silicon fuel pellets tested previously.
Date: March 1, 1996
Creator: Reimus, M.A.H. & George, T.G.
Partner: UNT Libraries Government Documents Department

Advanced Energy Projects FY 1996 research summaries

Description: The mission of the Advanced Energy Projects Division (AEP) is to explore the scientific feasibility of novel energy-related concepts. These concepts are typically at an early stage of scientific development and, therefore, are premature for consideration by applied research or technology development programs. The portfolio of projects is dynamic, but reflects the broad role of the Department in supporting research and development for improving the Nation`s energy posture. Topical areas presently receiving support include: alternative energy sources; innovative concepts for energy conversion and storage; alternate pathways to energy efficiency; exploring uses of new scientific discoveries; biologically-based energy concepts; renewable and biodegradable materials; novel materials for energy technology; and innovative approaches to waste treatment and reduction. Summaries of the 70 projects currently being supported are presented. Appendices contain budget information and investigator and institutional indices.
Date: September 1, 1996
Partner: UNT Libraries Government Documents Department

Lightweight Radioisotope Heater Unit (LWRHU) production for the Cassini mission

Description: The Lightweight Radioisotope Heater Unit (LWRHU) is a {sup 238}PuO{sub 2} fueled heat source designed to provide a thermal watt of power for space missions. The LWRHU will be used to maintain the temperature of various components on the spacecraft at the required level. The heat source consists of a {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh capsule, a pyrolytic graphite insulator, and a woven graphite aeroshell assembly. Los Alamos has fabricated 180 heater units, which will be used on the Cassini mission. This report summarizes the specifications, fabrication processes, and production data for the heat sources fabricated at Los Alamos.
Date: June 1, 1996
Creator: Rinehart, G.H.
Partner: UNT Libraries Government Documents Department

Automatic variance reduction for Monte Carlo simulations via the local importance function transform

Description: The author derives a transformed transport problem that can be solved theoretically by analog Monte Carlo with zero variance. However, the Monte Carlo simulation of this transformed problem cannot be implemented in practice, so he develops a method for approximating it. The approximation to the zero variance method consists of replacing the continuous adjoint transport solution in the transformed transport problem by a piecewise continuous approximation containing local biasing parameters obtained from a deterministic calculation. He uses the transport and collision processes of the transformed problem to bias distance-to-collision and selection of post-collision energy groups and trajectories in a traditional Monte Carlo simulation of ``real`` particles. He refers to the resulting variance reduction method as the Local Importance Function Transform (LIFI) method. He demonstrates the efficiency of the LIFT method for several 3-D, linearly anisotropic scattering, one-group, and multigroup problems. In these problems the LIFT method is shown to be more efficient than the AVATAR scheme, which is one of the best variance reduction techniques currently available in a state-of-the-art Monte Carlo code. For most of the problems considered, the LIFT method produces higher figures of merit than AVATAR, even when the LIFT method is used as a ``black box``. There are some problems that cause trouble for most variance reduction techniques, and the LIFT method is no exception. For example, the author demonstrates that problems with voids, or low density regions, can cause a reduction in the efficiency of the LIFT method. However, the LIFT method still performs better than survival biasing and AVATAR in these difficult cases.
Date: February 1, 1996
Creator: Turner, S.A.
Partner: UNT Libraries Government Documents Department

The effects of vent-notch area on bulging and thinning during the clad vent test closure-weld operation

Description: The internal gas pressure during clad vent set (CVS) welding is vented through aligned vent notches in each cup. For Galileo, Ulysses, and most of Cassini CVS production, the vent-notch dimensional requirements for both cups were as follows: (1) vent-notch depth, 0.15/0.20 mm; (2) vent-notch width, 0.25/0.35 nun; (3) bottom of vent-notch comers, sharp to full radius; (4) top of vent-notch edge, 0.05 mm maximum break; and (5) maximum variation between vent notch and grit-blasted triangle centerlines, 3{degrees}. During the fuel encapsulation operation (with {sup 238}PuO{sub 2} fuel pellets) at Los Alamos National Laboratory (LANL), excessive bulges or blowouts at the CVS closure-weld tie-in location occurred with 11.8% (27 out of 229) of the flight-quality welds made with the aforementioned standard vent-notch dimensions. These bulges and blowouts are primarily the result of inadequate venting of the increased gas pressure during the thermal cycle of the closure-weld operation. Proper venting is dependent mostly upon the weld parameters and the total vent-notch area. Because of the increased incidence of bulges/blowouts in the {sup 238}PuO{sub 2}-fueled CVS units, LANL personnel requested that consideration be given to increasing the vent-notch size to minimize further the loss of CVS hardware and the potential loss of {sup 238}PuO{sub 2} pellets. Thus, increasing further the production yield of the closure-weld operation would avoid potentially severe schedule delays.
Date: September 1, 1996
Creator: Ulrich, G. B.
Partner: UNT Libraries Government Documents Department

GPHS-RTGs in support of the Cassini Mission. Semi annual technical progress report, 1 April 1996--29 September 1996

Description: This technical progress report discusses work on the Radioisotope Generators and Ancillary Activities for the Cassini spacecraft. The Cassini spacecraft is expected to launch in October 1997, and will explore Saturn and its moons. This progress report discusses issues in: spacecraft integration and liason, engineering support, safety, qualified unicouple fabrication, ETG fabrication and testing, ground support equipment, RTG shipping and launch support, designs, reviews and mission application. Safety analysis of the RTGs during reentry and launch accidents are covered. This report covers the period of April 1 to September 29, 1996.
Date: October 20, 1996
Partner: UNT Libraries Government Documents Department

Plutonium Focus Area research and development plan. Revision 1

Description: The Department of Energy (DOE) committed to a research and development program to support the technology needs for converting and stabilizing its nuclear materials for safe storage. The R and D Plan addresses five of the six material categories from the 94-1 Implementation Plan: plutonium (Pu) solutions, plutonium metals and oxides, plutonium residues, highly enriched uranium, and special isotopes. R and D efforts related to spent nuclear fuel (SNF) stabilization were specifically excluded from this plan. This updated plan has narrowed the focus to more effectively target specific problem areas by incorporating results form trade studies. Specifically, the trade studies involved salt; ash; sand, slag, and crucible (SS and C); combustibles; and scrub alloy. The plan anticipates possible disposition paths for nuclear materials and identifies resulting research requirements. These requirements may change as disposition paths become more certain. Thus, this plan represents a snapshot of the current progress and will continue to be updated on a regular basis. The paper discusses progress in safeguards and security, plutonium stabilization, special isotopes stabilization, highly-enriched uranium stabilization--MSRE remediation project, storage technologies, engineered systems, core technology, and proposed DOE/Russian technology exchange projects.
Date: November 1, 1996
Partner: UNT Libraries Government Documents Department

GPHS-RTGs in support of the Cassini mission. Semi annual technical progress report, 2 October 1995--31 March 1996

Description: The technical progress achieved during the period 2 October 1995 through 31 March 1996 on Contract No. DE-AC03-91SF18852, Radioisotope Generators and Ancillary Activities is described herein. This report is organized by the program task structure as follows: spacecraft integration and liaison; engineering support; safety; qualified unicouple fabrication; ETG fabrication, assembly, and test; ground support equipment (GSE); RTG shipping and launch support; designs, reviews, and mission applications; project management, quality assurance and reliability, contract changes, non-capital CAGO acquisition, and CAGO maintenance; contract acquired government-owned property (CAGO) acquisition; and program calendars.
Date: April 20, 1996
Partner: UNT Libraries Government Documents Department

Monthly technical progress report, January 1, 1996 - January 28, 1996

Description: This is the January 1996 progress report contract DE-AC03-91SF18852 Radioisotope Thermoelectric Generators and Ancillary Activities, Cassini RTG Program. Included are discussions on the status of: (1) spacecraft integration and support, (2) engineering support, (3) safety, (4) qualified unicouple production, (5) ETG fabrication, Assembly, and Test, (6) ground support equipment, (7) RTG shipping and launch support, (8) designs, reviews, and mission applications, (9) project management, and (10) CAGO acquisition.
Date: February 24, 1996
Partner: UNT Libraries Government Documents Department

Monthly technical report progress by major report, 29 April--26 May 1996

Description: This article is the May 1996 monthly report for the Cassini RTG Program. Items covered include: (1) Spacecraft integration and liason, (2) Engineering support, (3) Safety, (4) Qualified unicouple production, (5) ETG fabrication, assembly, and test, (6) Ground support equipment, (7) RTG shipping and launch support, (8) Designs, reviews, and mission applications, and (10) Project management, QA, reliability, contract changes, and CAGO acquisition, maintenance, and repair.
Date: June 1, 1996
Partner: UNT Libraries Government Documents Department

Surplus weapons-grade plutonium: a resource for exploring and terraforming Mars

Description: With the end of the Cold War, greater than 100 metric tons (MT) of weapons-grade plutonium (WGPu) have become surplus to defense needs in the United States and the Former Soviet Union. This paper is a proposal for an option for WGPu disposition, i.e., use of the plutonium as a fuel for nuclear reactors for Mars exploration and eventual terraforming. WGPu was used in nuclear weapons because it has a much smaller critical mass than highly enriched uranium, allowing lighter weapons with consequent longer ranges. Similarly, WGPu reactors would also require smaller amounts of fuel to attain a critical mass, making the reactor much lighter overall and resulting in large savings in launch costs. The greater than 100 MT of WGPu would generate about 1000 billion kilowatt hours of heat energy, much of which could be converted into electricity. The waste heat would also be useful to a Martian outpost or colony. A potential way of getting the WGPu reactors into space is a large gas gun like that being developed at the Lawrence Livermore National Laboratory to orbit materials by achieving high velocity at the surface, greatly reducing launch costs and enhancing reliability. Reactor components would be launched on conventional rockets or space shuttles, the reactor fuel rods would be injected into orbit using the gas gun, and the reactor would be assembled in space. Implementation of this proposal would allow disposition of a serious, expensive problem on earth by removing the WGPu from the planet and simultaneously provide a very large energy resource for Mars exploration and terraforming.
Date: December 31, 1996
Creator: Muscatello, A.C. & Houts, M.G.
Partner: UNT Libraries Government Documents Department

High Performance Ultra-light Nuclear Rockets for NEO (Near Earth Objects) Interaction Missions

Description: The performance capabilities and technology features of ultra compact nuclear thermal rockets based on very high power density ({approximately} 30 Megawatts per liter) fuel elements are described. Nuclear rockets appear particularly attractive for carrying out missions to investigate or intercept Near Earth Objects (NEOS) that potentially could impact on the Earth. Many of these NEO threats, whether asteroids or comets, have extremely high closing velocities, i.e., tens of kilometers per second relative to the Earth. Nuclear rockets using hydrogen propellant enable flight velocities 2 to 3 times those achievable with chemical rockets, allowing interaction with a potential NEO threat at a much shorter time, and at much greater range. Two versions of an ultra compact nuclear rocket based on very high heat transfer rates are described: the PBR (Particle Bed Reactor), which has undergone substantial hardware development effort, and MITEE (Miniature Reactor Engine) which is a design derivative of the PBR. Nominal performance capabilities for the PBR are: thermal power - 1000 MW thrust - 45,000 lbsf, and weight - 500 kg. For MITEE, nominal capabilities are: thermal power - 100 MW; thrust {approx} 4500 lbsf, and weight - 50 kg. Development of operational PBR/MITEE systems would enable spacecraft launched from LEO (Low Earth Orbit) to investigate intercept NEO`s at a range of {approximately} 100 million kilometers in times of {approximately} 30 days.
Date: December 31, 1996
Creator: Powell, J.; Maise, G.; Ludewig, H. & Todosow, M.
Partner: UNT Libraries Government Documents Department