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  1. Gas core nuclear thermal rocket engine research and development in the former USSR

    Beginning in 1957 and continuing into the mid 1970s, the USSR conducted an extensive investigation into the use of both solid and gas core nuclear thermal rocket engines for space missions. During this time the scientific and engineering. problems associated with the development of a solid core engine were resolved. At the same time research was undertaken on a gas core engine, and some of the basic engineering problems associated with the concept were investigated. At the conclusion of the program, the basic principles of the solid core concept were established. However, a prototype solid core engine was not builtmore » because no established mission required such an engine. For the gas core concept, some of the basic physical processes involved were studied both theoretically and experimentally. However, no simple method of conducting proof-of-principle tests in a neutron flux was devised. This report focuses primarily on the development of the. gas core concept in the former USSR. A variety of gas core engine system parameters and designs are presented, along with a summary discussion of the basic physical principles and limitations involved in their design. The parallel development of the solid core concept is briefly described to provide an overall perspective of the magnitude of the nuclear thermal propulsion program and a technical comparison with the gas core concept.« less
  2. Gas core nuclear thermal rocket engine research and development in the former USSR

    Beginning in 1957 and continuing into the mid 1970s, the USSR conducted an extensive investigation into the use of both solid and gas core nuclear thermal rocket engines for space missions. During this time the scientific and engineering. problems associated with the development of a solid core engine were resolved. At the same time research was undertaken on a gas core engine, and some of the basic engineering problems associated with the concept were investigated. At the conclusion of the program, the basic principles of the solid core concept were established. However, a prototype solid core engine was not builtmore » because no established mission required such an engine. For the gas core concept, some of the basic physical processes involved were studied both theoretically and experimentally. However, no simple method of conducting proof-of-principle tests in a neutron flux was devised. This report focuses primarily on the development of the. gas core concept in the former USSR. A variety of gas core engine system parameters and designs are presented, along with a summary discussion of the basic physical principles and limitations involved in their design. The parallel development of the solid core concept is briefly described to provide an overall perspective of the magnitude of the nuclear thermal propulsion program and a technical comparison with the gas core concept.« less
  3. Distributed production system for {sup 99m}Tc-I: System overview

    Technetium-99m is the radioisotope of choice for >80% of all nuclear medical imaging procedures today in the United States. There are > 12 million {sup 99m}Tc scans performed in the United States per year. Since the development of fission-based radio nuclide generators for {sup 99}Mo, {sup 99m}Tc use has grown steadily over the past 20 yr. Despite the widespread demand for {sup 99m}Tc in medicine, a reliable and assured supply of the parent, {sup 99}Mo, does not exist. Construction of Maple-1 and -2, two new Canadian isotope production reactors intended to replace the aging National Research Universal (NRU) reactor, hasmore » been approved in an agreement among Atomic Energy of Canada Limited, MDS Nordion, and the Canadian government. However, the project is expensive: The anticipated cost of Maple-1 and -2 is $C140 million. Outlays toward this cost have recently driven the price of {sup 99}Mo up by 40%, even though the Canadian {sup 99}Mo production will continue to be heavily subsidized by an interest-free construction loan. Research and development for an accelerator-based facility has been undertaken and is described.« less
  4. Thermo-chemical modeling of internal-reforming SOFCs at the Idaho National Engineering Laboratory

    The Idaho National Engineering Laboratory is performing research and development of a cross-flow, internal-reforming SOFC. Part of the effort entails development of a thermo-chemical computer model to execute scoping, design, and performance studies of the INTEL SOFC design. A one-dimensional model is being completed and extensions to two and three-dimensions are planned. Mass, heat, electrochemical, and chemical kinetic balance equations are presented along with preliminary simulation results.
  5. A system of {sup 99m}Tc production based on distributed electron accelerators and thermal separation

    A system has been developed for the production of {sup 99m}Tc based on distributed electron accelerators and thermal separation. The radioactive decay parent of {sup 99m}Tc, {sup 99}Mo, is produced from {sup 100}Mo by a photoneutron reaction. Two alternative thermal separation processes have been developed to extract {sup 99m}Tc. Experiments have been performed to verify the technical feasibility of the production and assess the efficiency of the extraction processes. A system based on this technology enables the economical supply of {sup 99m}Tc for a large nuclear pharmacy. Twenty such production centers distributed near major metropolitan areas could produce the entiremore » US supply of {sup 99m}Tc at a cost less than the current subsidized price.« less
  6. User's guide for numerical modeling of buoyant plumes in a turbulent, stratified atmosphere

    A widely applicable computational model of buoyant, bent-over plumes in realistic atmospheres is constructed. To do this, the two-dimensional, time-dependent fluid mechanics equations are numerically integrated, while a number of important physical approximations serve to keep the approach at a tractable level. A three-dimensional picture of a steady state plume is constructed from a sequence of time-dependent, two-dimensional plume cross sections--each cross section of the sequence is spaced progressively further downwind as it is advected for a progressively longer time by the prevailing wind. The dynamics of the plume simulations are quite general. The buoyancy sources in the plume includemore » the sensible heat in the plume, the latent heat absorbed or released in plume moisture processes, and the heating of the plume by a radioactive pollutant in the plume. The atmospheric state in the simulations is also quite general. Atmospheric variables are allowed to be functions of height, and the ambient atmospheric turbulence (also a function of height) is included in the simulations.« less
  7. Core gas dynamics and heat transfer analyses of the COMET nuclear thermal rocket engine

    There has been a renewed interest in nuclear space propulsion for both the Space Exploration Initiative and military missions. The conical multiple element thruster (COMET) nuclear-thermal rocket engine discussed in this paper is one of several designs that have been proposed as an alternative to the pellet-bed reactor, which the US Air Force has been developing for various military space missions. COMET was designed to have a thrust of 75,000 lb[sub f] and a specific impulse of 900 to 1000 s. The nuclear reactor subsystem consists of 37 fuel assemblies. The core geometry is conical, as is the shape ofmore » each individual assembly. A typical fuel assembly, consists of a conical hot flow channel surrounded by a conical fueled region. The fuel region contains [approx] 500 conical fuel wafers, which are each 0.5 mm thick. Each wafer is separated from the adjacent wafers by a 0.1-mm coolant channel, resulting in a fueled region porosity of 20%. Surrounding the fuel region is an annular inlet flow channel. The hydrogen propellant enters the inlet flow channel at the upper end of the fuel assembly at a temperature of [approx] 300 K. As the hydrogen flows down the inlet channel, it is diverted into the narrow fuel coolant channels and heated to [approx] 3150 K as it exits the fuel. The work reported here involved modeling the flow through the conical coolant channels and the hot flow duct of COMET fuel assemblies.« less
  8. Interferometric investigation of turbulently fluctuating temperature in an LMFBR outlet plenum geometry

    A novel optical technique is described for the measurement of turbulently fluctuating temperature in a transparent fluid flow. The technique employs a Mach-Zehnder interferometer of extremely short field and a simple photoconductive diode detector. The system produces a nearly linear D.C. electrical analog of the turbulent temperature fluctuations in a small, 1 mm/sup 3/ volume. The frequency response extends well above 2500 Hz, and can be improved by the choice of a more sophisticated photodetector. The turbulent sodium mixing in the ANL 1/sup 1///sub 15/-scale FFTF outlet plenum is investigated with a scale model outlet mixing plenum, using flows ofmore » air. The scale design represents a cross section of the ANL outlet plenum, so that the average recirculating flow inside the test cell is two dimensional. The range of the instrument is 120/sup 0/F above the ambient air temperature. The accuracy is generally +-5/sup 0/F, with most of the error due to noise originating from building vibrations and room noise. The power spectral density of the fluctuating temperature has been observed experimentally at six different stations in the flow. A strong 300 Hz component is generated in the inlet region, which decays as the flow progresses along streamlines. The effect of the inlet Reynolds number and the temperature difference between the inlet flows on the power spectral density has also been investigated. Traces of the actual fluctuating temperature are included for the six stations.« less
  9. Finite element stress analysis for coated particle fuel modeling under normal operating conditions

    This paper reports on finite element modeling of the stresses in TRISO-coated fuel particles under normal operating conditions that is undertaken with the ABAQUS code. Accurate results for the coating layer stresses are obtained with 30 finite elements in the model and {approximately}100 time steps through the life of the fuel. When compared to an earlier General Atomics/Forschungszentrum Julich (Ga/KFA) computer model of fuel performance, several discrepancies are uncovered in the earlier model. The GA/KFA model underpredicts the stresses in the silicon carbide layer, and the discrepancy increases with fission gas pressure.
  10. Hemangiosarcoma subsequent to radiotherapy for a hemangioma in infancy

    A case is presented of a 31-year-old white man who developed a hemangiosarcoma in the very place where 30 years ago a hemangioma had been treated by radiotherapy. The rarity of such an occurrence is attested to by the fact that only two similar cases were found in the English medical literature.
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