Sample records for silicide fuel behavior

  1. Simulated Fission Gas Behavior in Silicide Fuel at LWR Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Mo, Kun [Argonne National Lab. (ANL), Argonne, IL (United States); Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States); Harp, Jason [Argonne National Lab. (ANL), Argonne, IL (United States)


    As a promising candidate for the accident tolerant fuel (ATF) used in light water reactors (LWRs), the fuel performance of uranium silicide (U3Si2) at LWR conditions needs to be well-understood. However, existing experimental post-irradiation examination (PIE) data are limited to the research reactor conditions, which involve lower fuel temperature compared to LWR conditions. This lack of appropriate experimental data significantly affects the development of fuel performance codes that can precisely predict the microstructure evolution and property degradation at LWR conditions, and therefore evaluate the qualification of U3Si2 as an AFT for LWRs. Considering the high cost, long timescale, and restrictive access of the in-pile irradiation experiments, this study aims to utilize ion irradiation to simulate the inpile behavior of the U3Si2 fuel. Both in situ TEM ion irradiation and ex situ high-energy ATLAS ion irradiation experiments were employed to simulate different types of microstructure modifications in U3Si2. Multiple PIE techniques were used or will be used to quantitatively analyze the microstructure evolution induced by ion irradiation so as to provide valuable reference for the development of fuel performance code prior to the availability of the in-pile irradiation data.

  2. Behavior of silicon in nitric media. Application to uranium silicides fuels reprocessing; Comportement du silicium en milieu nitrique. Application au retraitement des combustibles siliciures d'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Cheroux, L


    Uranium silicides are used in some research reactors. Reprocessing them is a solution for their cycle end. A list of reprocessing scenarios has been set the most realistic being a nitric dissolution close to the classic spent fuel reprocessing. This uranium silicide fuel contains a lot of silicon and few things are known about polymerization of silicic acid in concentrated nitric acid. The study of this polymerization allows to point out the main parameters: acidity, temperature, silicon concentration. The presence of aluminum seems to speed up heavily the polymerization. It has been impossible to find an analytical technique smart and fast enough to characterize the first steps of silicic acid polymerization. However the action of silicic species on emulsions stabilization formed by mixing them with an organic phase containing TBP has been studied, Silicon slows down the phase separation by means of oligomeric species forming complex with TBP. The existence of these intermediate species is short and heating can avoid any stabilization. When non irradiated uranium silicide fuel is attacked by a nitric solution, aluminum and uranium are quickly dissolved whereas silicon mainly stands in solid state. That builds a gangue of hydrated silica around the uranium silicide particulates without preventing uranium dissolution. A small part of silicon passes into the solution and polymerize towards the highly poly-condensed forms, just 2% of initial silicon is still in molecular form at the end of the dissolution. A thermal treatment of the fuel element, by forming inter-metallic phases U-Al-Si, allows the whole silicon to pass into the solution and next to precipitate. The behavior of silicon in spent fuels should be between these two situations. (author)

  3. Development of molecular dynamics potential for uranium silicide fuels

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jianguo; Zhang, Yongfeng; Hales, Jason D.


    Use of uranium–silicide (U-Si) in place of uranium dioxide (UO2) is one of the promising concepts being proposed to increase the accident tolerance of nuclear fuels. This is due to a higher thermal conductivity than UO2 that results in lower centerline temperatures. U-Si also has a higher fissile density, which may enable some new cladding concepts that would otherwise require increased enrichment limits to compensate for their neutronic penalty. However, many critical material properties for U-Si have not been determined experimentally. For example, silicide compounds (U3Si2 and U3Si) are known to become amorphous under irradiation. There was clear independent experimental evidence to support a crystalline to amorphous transformation in those compounds. However, it is still not well understood how the amorphous transformation will affect on fuel behavior. It is anticipated that modeling and simulation may deliver guidance on the importance of various properties and help prioritize experimental work. In order to develop knowledge-based models for use at the engineering scale with a minimum of empirical parameters and increase the predictive capabilities of the developed model, inputs from atomistic simulations are essential. First-principles based density functional theory (DFT) calculations will provide the most reliable information. However, it is probably not possible to obtain kinetic information such as amorphization under irradiation directly from DFT simulations due to size and time limitations. Thus, a more feasible way may be to employ molecular dynamics (MD) simulation. Unfortunately, so far no MD potential is available for U-Si to discover the underlying mechanisms. Here, we will present our recent progress in developing a U-Si potential from ab initio data. This work is supported by the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program funded by the U.S. Department of Energy, Office of Nuclear Energy.

  4. Radiation Re-solution Calculation in Uranium-Silicide Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Unal, Cetin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    The release of fission gas from nuclear fuels is of primary concern for safe operation of nuclear power plants. Although the production of fission gas atoms can be easily calculated from the fission rate in the fuel and the average yield of fission gas, the actual diffusion, behavior, and ultimate escape of fission gas from nuclear fuel depends on many other variables. As fission gas diffuses through the fuel grain, it tends to collect into intra-granular bubbles, as portrayed in Figure 1.1. These bubbles continue to grow due to absorption of single gas atoms. Simultaneously, passing fission fragments can cause collisions in the bubble that result in gas atoms being knocked back into the grain. This so called “re-solution” event results in a transient equilibrium of single gas atoms within the grain. As single gas atoms progress through the grain, they will eventually collect along grain boundaries, creating inter-granular bubbles. As the inter-granular bubbles grow over time, they will interconnect with other grain-face bubbles until a pathway is created to the outside of the fuel surface, at which point the highly pressurized inter-granular bubbles will expel their contents into the fuel plenum. This last process is the primary cause of fission gas release. From the simple description above, it is clear there are several parameters that ultimately affect fission gas release, including the diffusivity of single gas atoms, the absorption and knockout rate of single gas atoms in intra-granular bubbles, and the growth and interlinkage of intergranular bubbles. Of these, the knockout, or re-solution rate has an particularly important role in determining the transient concentration of single gas atoms in the grain. The re-solution rate will be explored in the following sections with regards to uranium-silicide fuels in order to support future models of fission gas bubble behavior.

  5. Status of the atomized uranium silicide fuel development at KAERI

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.K.; Kim, K.H.; Park, H.D.; Kuk, I.H. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)


    While developing KMRR fuel fabrication technology an atomizing technique has been applied in order to eliminate the difficulties relating to the tough property of U{sub 3}Si and to take advantage of the rapid solidification effect of atomization. The comparison between the conventionally comminuted powder dispersion fuel and the atomized powder dispersion fuel has been made. As the result, the processes, uranium silicide powdering and heat treatment for U{sub 3}Si transformation, become simplified. The workability, the thermal conductivity and the thermal compatibility of fuel meat have been investigated and found to be improved due to the spherical shape of atomized powder. In this presentation the overall developments of atomized U{sub 3}Si dispersion fuel and the planned activities for applying the atomizing technique to the real fuel fabrication are described.

  6. Dual fuel gradients in uranium silicide plates

    Energy Technology Data Exchange (ETDEWEB)

    Pace, B.W. [Babock and Wilcox, Lynchburg, VA (United States)


    Babcock & Wilcox has been able to achieve dual gradient plates with good repeatability in small lots of U{sub 3}Si{sub 2} plates. Improvements in homogeneity and other processing parameters and techniques have allowed the development of contoured fuel within the cladding. The most difficult obstacles to overcome have been the ability to evaluate the bidirectional fuel loadings in comparison to the perfect loading model and the different methods of instilling the gradients in the early compact stage. The overriding conclusion is that to control the contour of the fuel, a known relationship between the compact, the frames and final core gradient must exist. Therefore, further development in the creation and control of dual gradients in fuel plates will involve arriving at a plausible gradient requirement and building the correct model between the compact configuration and the final contoured loading requirements.

  7. Rate Theory Modeling and Simulations of Silicide Fuel at LWR Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Ye, Bei [Argonne National Lab. (ANL), Argonne, IL (United States); Mei, Zhigang [Argonne National Lab. (ANL), Argonne, IL (United States); Hofman, Gerard [Argonne National Lab. (ANL), Argonne, IL (United States); Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States)


    Uranium silicide (U3Si2) fuel has higher thermal conductivity and higher uranium density, making it a promising candidate for the accident-tolerant fuel (ATF) used in light water reactors (LWRs). However, previous studies on the fuel performance of U3Si2, including both experimental and computational approaches, have been focusing on the irradiation conditions in research reactors, which usually involve low operation temperatures and high fuel burnups. Thus, it is important to examine the fuel performance of U3Si2 at typical LWR conditions so as to evaluate the feasibility of replacing conventional uranium dioxide fuel with this silicide fuel material. As in-reactor irradiation experiments involve significant time and financial cost, it is appropriate to utilize modeling tools to estimate the behavior of U3Si2 in LWRs based on all those available research reactor experimental references and state-of-the-art density functional theory (DFT) calculation capabilities at the early development stage. Hence, in this report, a comprehensive investigation of the fission gas swelling behavior of U3Si2 at LWR conditions is introduced. The modeling efforts mentioned in this report was based on the rate theory (RT) model of fission gas bubble evolution that has been successfully applied for a variety of fuel materials at devious reactor conditions. Both existing experimental data and DFT-calculated results were used for the optimization of the parameters adopted by the RT model. Meanwhile, the fuel-cladding interaction was captured by the coupling of the RT model with simplified mechanical correlations. Therefore, the swelling behavior of U3Si2 fuel and its consequent interaction with cladding in LWRs was predicted by the rate theory modeling, providing valuable information for the development of U3Si2 fuel as an accident

  8. Rate Theory Modeling and Simulation of Silicide Fuel at LWR Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Ye, Bei [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Hofman, Gerard [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Gamble, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation; Mei, Zhi-Gang [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division


    As a promising candidate for the accident tolerant fuel (ATF) used in light water reactors (LWRs), the fuel performance of uranium silicide (U3Si2) at LWR conditions needs to be well understood. In this report, rate theory model was developed based on existing experimental data and density functional theory (DFT) calculations so as to predict the fission gas behavior in U3Si2 at LWR conditions. The fission gas behavior of U3Si2 can be divided into three temperature regimes. During steady-state operation, the majority of the fission gas stays in intragranular bubbles, whereas the dominance of intergranular bubbles and fission gas release only occurs beyond 1000 K. The steady-state rate theory model was also used as reference to establish a gaseous swelling correlation of U3Si2 for the BISON code. Meanwhile, the overpressurized bubble model was also developed so that the fission gas behavior at LOCA can be simulated. LOCA simulation showed that intragranular bubbles are still dominant after a 70 second LOCA, resulting in a controllable gaseous swelling. The fission gas behavior of U3Si2 at LWR conditions is benign according to the rate theory prediction at both steady-state and LOCA conditions, which provides important references to the qualification of U3Si2 as a LWR fuel material with excellent fuel performance and enhanced accident tolerance.

  9. Oxidation behavior of multiphase molybdenum-molybdenum silicide-molybdenum silicide boride intermetallics (United States)

    Dheeradhada, Voramon Supatarawanich

    Multiphase Mo-Mo3Si-Mo5SiB2(T2) alloys of various compositions and microstructures were investigated for oxidation resistance at 800 and 1300°C. The alloys varied in Si/B ratio from 1:1 to 1:2 and their microstructures were processed to have the Mo phase distributed as a continuous phase or as discrete particles. At 800°C, the alloys exhibited poor oxidation resistance regardless of Si/B ratio or their microstructures. Oxide scale consisted of MoO 3 and boron-containing glass. Alloys with lower Si/B ratio yielded silicate glass with lower viscosity that resulted in lower weight loss compared to the high Si/B ratio alloys. Intermediate layers of Mo and Mo-Si-O were observed adjacent to Mo5SiB2 and Mo3Si phases, respectively. At 1300°C, the multiphase alloys developed a protective glass scale with an intermediate layer of (Mo+glass) between the base alloy and outer glass scale. Boron-lean silicate glass was essential for the protection from further oxidation. For oxidation resistance at 1300°C, alloys require a high Si/B ratio. In terms of microstructures, the multiphase alloys consisting of small Mo particles uniformly dispersed in fine spacing of silicide phases provide better oxidation resistance than the alloys with continuous Mo dendrites. Glass preferentially formed at Mo3Si rather than at T2 phase. Vapor-solid diffusion experiments were carried out with single phase alloys containing either Mo3Si or T2 as the major phase, and the multiphase Mo-10Si-10B(at%) alloy. The alloys were exposed to vacuum to induce silicon loss resulting in the formation of a Mo layer. In addition, microprobe analysis was carried out for the determination of composition profiles across the (Mo+glass) layer and the external glass scale formed on the Mo-13.2Si-13.2B (at%) alloy oxidized at 1300°C. The microprobe data were analyzed for interdiffusion fluxes and interdiffusion coefficients with the aid of a computer program called "MultiDiFlux (c)". The effective interdiffusion

  10. The whole-core LEU silicide fuel demonstration in the JMTR

    Energy Technology Data Exchange (ETDEWEB)

    Aso, Tomokazu; Akashi, Kazutomo; Nagao, Yoshiharu [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)] [and others


    The JMTR was fully converted to LEU silicide (U{sub 3}Si{sub 2}) fuel with cadmium wires as burnable absorber in January, 1994. The reduced enrichment program for the JMTR was initiated in 1979, and the conversion to MEU (enrichment ; 45%) aluminide fuel was carried out in 1986 as the first step of the program. The final goal of the program was terminated by the present LEU conversion. This paper describes the results of core physics measurement through the conversion phase from MEU fuel core to LEU fuel core. Measured excess reactivities of the LEU fuel cores are mostly in good agreement with predicted values. Reactivity effect and burnup of cadmium wires, therefore, were proved to be well predicted. Control rod worth in the LEU fuel core is mostly less than that in the MEU fuel core. Shutdown margin was verified to be within the safety limit. There is no significant difference in temperature coefficient of reactivity between the MEU and LEU fuel cores. These results verified that the JMTR was successfully and safely converted to LEU fuel. Extension of the operating cycle period was achieved and reduction of spend fuel elements is expected by using the fuel with high uranium density.

  11. Status of core conversion with LEU silicide fuel in JRR-4

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Teruo; Ohnishi, Nobuaki; Shirai, Eiji [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)


    Japan Research Reactor No.4 (JRR-4) is a light water moderated and cooled, 93% enriched uranium ETR-type fuel used and swimming pool type reactor with thermal output of 3.5MW. Since the first criticality was achieved on January 28, 1965, JRR-4 has been used for shielding experiments, radioisotope production, neutron activation analyses, training for reactor engineers and so on for about 30 years. Within the framework of the RERTR Program, the works for conversion to LEU fuel are now under way, and neutronic and thermal-hydraulic calculations emphasizing on safety and performance aspects are being carried out. The design and evaluation for the core conversion are based on the Guides for Safety Design and Evaluation of research and testing reactor facilities in Japan. These results show that the JRR-4 will be able to convert to use LEU fuel without any major design change of core and size of fuel element. LEU silicide fuel (19.75%) will be used and maximum neutron flux in irradiation hole would be slightly decreased from present neutron flux value of 7x10{sup 13}(n/cm{sup 2}/s). The conversion works are scheduled to complete in 1998, including with upgrade of the reactor building and utilization facilities.

  12. Vertically grown multiwalled carbon nanotube anode and nickel silicide integrated high performance microsized (1.25 μl) microbial fuel cell

    KAUST Repository

    Mink, Justine E.


    Microbial fuel cells (MFCs) are an environmentally friendly method for water purification and self-sustained electricity generation using microorganisms. Microsized MFCs can also be a useful power source for lab-on-a-chip and similar integrated devices. We fabricated a 1.25 μL microsized MFC containing an anode of vertically aligned, forest type multiwalled carbon nanotubes (MWCNTs) with a nickel silicide (NiSi) contact area that produced 197 mA/m 2 of current density and 392 mW/m 3 of power density. The MWCNTs increased the anode surface-to-volume ratio, which improved the ability of the microorganisms to couple and transfer electrons to the anode. The use of nickel silicide also helped to boost the output current by providing a low resistance contact area to more efficiently shuttle electrons from the anode out of the device. © 2012 American Chemical Society.

  13. Safety evaluation report related to the evaluation of low-enriched uranium silicide-aluminum dispersion fuel for use in non-power reactors

    Energy Technology Data Exchange (ETDEWEB)


    Low-enriched uranium silicide-aluminum dispersion plate-type fuels have been extensively researched and developed under the international program, Reduced Enrichment in Research and Test Reactors. The international effort was led by Argonne National Laboratory (ANL) in the United States. This evaluation is based primarily on reports issued by ANL that discuss and summarize the developmental tests and experiments, including postirradiation examinations, of both miniature and full-sized plates of prototypical fuel compositions. This evaluation concludes that plate-type fuels suitable and acceptable for use in research and test reactors can be fabricated with U/sub 3/Si/sub 2/-Al dispersion compacts with uranium densities up to 4.8 g/cm/sup 3/. 4 refs., 1 fig.

  14. High temperature structural silicides

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.


    Structural silicides have important high temperature applications in oxidizing and aggressive environments. Most prominent are MoSi{sub 2}-based materials, which are borderline ceramic-intermetallic compounds. MoSi{sub 2} single crystals exhibit macroscopic compressive ductility at temperatures below room temperature in some orientations. Polycrystalline MoSi{sub 2} possesses elevated temperature creep behavior which is highly sensitive to grain size. MoSi{sub 2}-Si{sub 3}N{sub 4} composites show an important combination of oxidation resistance, creep resistance, and low temperature fracture toughness. Current potential applications of MoSi{sub 2}-based materials include furnace heating elements, molten metal lances, industrial gas burners, aerospace turbine engine components, diesel engine glow plugs, and materials for glass processing.

  15. Copper silicide/silicon nanowire heterostructures: in situ TEM observation of growth behaviors and electron transport properties. (United States)

    Chiu, Chung-Hua; Huang, Chun-Wei; Chen, Jui-Yuan; Huang, Yu-Ting; Hu, Jung-Chih; Chen, Lien-Tai; Hsin, Cheng-Lun; Wu, Wen-Wei


    Copper silicide has been studied in the applications of electronic devices and catalysts. In this study, Cu3Si/Si nanowire heterostructures were fabricated through solid state reaction in an in situ transmission electron microscope (TEM). The dynamic diffusion of the copper atoms in the growth process and the formation mechanism are characterized. We found that two dimensional stacking faults (SF) may retard the growth of Cu3Si. Due to the evidence of the block of edge-nucleation (heterogeneous) by the surface oxide, center-nucleation (homogeneous) is suggested to dominate the silicidation. Furthermore, the electrical transport properties of various silicon channel length with Cu3Si/Si heterostructure interfaces and metallic Cu3Si NWs have been investigated. The observations not only provided an alternative pathway to explore the formation mechanisms and interface properties of Cu3Si/Si, but also suggested the potential application of Cu3Si at nanoscale for future processing in nanotechnology.

  16. Thermoelectric Properties of Semiconducting Silicide Nanowires (United States)

    Jin, Song; Sczech, Jeannine; Higgins, Jeremy; Zhou, Feng; Shi, Li


    Semiconducting silicides are promising thermoelectric materials. In addition to their respectable thermoelectric figure-of-merit (ZT up to 0.8), silicides have the advantages of low cost, excellent thermal stability and mechanical strength, and outstanding oxidation resistance, making them suitable for high temperature applications. We have developed general synthetic approaches to single crystal nanowires of silicides to investigate the enhancement of thermoelectric properties due to the reduced nanoscale dimension and to explore their applications in thermoelectrics. We will discuss the synthesis and structural characterization of nanowires of chromium disilicide (CrSi2) prepared via a chemical vapor transport (CVT) method and chemical vapor deposition (CVD) of organometallic precursors to synthesize the Novontony Chimney ladder phase MnSi1.75. The Seebeck coefficient, electrical conductivity, and thermal conductivity of individual CrSi2 nanowires were characterized using a suspended microdevice and correlated with the structural information obtained by microscopy on the same nanowires. This combined Seebeck coefficient and electrical conductivity measurements also provide an effective approach to probing the Fermi level, carrier concentration and mobility in nanowires. We will also discuss our progress in using individual nanostructures combined well-defined structural characterization to conclusively investigate the complex thermoelectric behaviors of silicide materials.

  17. Fire behavior in masticated fuels: a review (United States)

    Jesse K. Kreye; Nolan W. Brewer; Penelope Morgan; J. Morgan Varner; Alistair M.S. Smith; Chad M. Hoffman; Roger D. Ottmar


    Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity, but fuel models do not exist for predicting fire behavior in these fuel types. Recent fires burning in masticated fuels have behaved in unexpected and contradictory ways, likely...

  18. A physical description of fission product behavior fuels for advanced power reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Kaganas, G.; Rest, J.; Nuclear Engineering Division; Florida International Univ.


    The Global Nuclear Energy Partnership (GNEP) is considering a list of reactors and nuclear fuels as part of its chartered initiative. Because many of the candidate materials have not been explored experimentally under the conditions of interest, and in order to economize on program costs, analytical support in the form of combined first principle and mechanistic modeling is highly desirable. The present work is a compilation of mechanistic models developed in order to describe the fission product behavior of irradiated nuclear fuel. The mechanistic nature of the model development allows for the possibility of describing a range of nuclear fuels under varying operating conditions. Key sources include the FASTGRASS code with an application to UO{sub 2} power reactor fuel and the Dispersion Analysis Research Tool (DART ) with an application to uranium-silicide and uranium-molybdenum research reactor fuel. Described behavior mechanisms are divided into subdivisions treating fundamental materials processes under normal operation as well as the effect of transient heating conditions on these processes. Model topics discussed include intra- and intergranular gas-atom and bubble diffusion, bubble nucleation and growth, gas-atom re-solution, fuel swelling and ?scion gas release. In addition, the effect of an evolving microstructure on these processes (e.g., irradiation-induced recrystallization) is considered. The uranium-alloy fuel, U-xPu-Zr, is investigated and behavior mechanisms are proposed for swelling in the {alpha}-, intermediate- and {gamma}-uranium zones of this fuel. The work reviews the FASTGRASS kinetic/mechanistic description of volatile ?scion products and, separately, the basis for the DART calculation of bubble behavior in amorphous fuels. Development areas and applications for physical nuclear fuel models are identified.

  19. Sensitivity of fire behavior simulations to fuel model variations (United States)

    Lucy A. Salazar


    Stylized fuel models, or numerical descriptions of fuel arrays, are used as inputs to fire behavior simulation models. These fuel models are often chosen on the basis of generalized fuel descriptions, which are related to field observations. Site-specific observations of fuels or fire behavior in the field are not readily available or necessary for most fire management...

  20. Nanoscale contact engineering for Silicon/Silicide nanowire devices (United States)

    Lin, Yung-Chen

    Metal silicides have been used in silicon technology as contacts to achieve high device performance and desired device functions. The growth and applications of silicide materials have recently attracted increasing interest for nanoscale device applications. Nanoscale silicide materials have been demonstrated with various synthetic approaches. Solid state reaction wherein high quality silicides form through diffusion of metal atoms into silicon nano-templates and the subsequent phase transformation caught significant attention for the fabrication of nanoscale Si devices. Very interestingly, studies on the diffusion and phase transformation processes at nanoscale have indicated possible deviations from the bulk and the thin film system. Here we studied growth kinetics, electronic properties and device applications of nanoscale silicides formed through solid state reaction. We have grown single crystal PtSi nanowires and PtSi/Si/PtSi nanowire heterostructures through solid state reaction. TEM studies show that the heterostructures have atomically sharp interfaces free of defects. Electrical measurement of PtSi nanowires shows a low resistivity of ˜28.6 μΩ·cm and a high breakdown current density beyond 108 A/cm2. Furthermore, using single-crystal PtSi/Si/PtSi nanowire heterostructures with atomically clean interfaces, we have fabricated p-channel enhancement mode transistors with the best reported performance for intrinsic silicon nanowires to date. In our results, silicide can provide a clean and no Fermi level pinning interface and then silicide can form Ohmic-contact behavior by replacing the source/drain metal with PtSi. It has been proven by our experiment by contacting PtSi with intrinsic Si nanowires (no extrinsic doping) to achieve high performance p-channel device. By utilizing the same approach, single crystal MnSi nanowires and MnSi/Si/MnSi nanowire heterojunction with atomically sharp interfaces can also been grown. Electrical transport studies on Mn

  1. Reactive growth of niobium silicides in bulk diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Milanese, Chiara; Buscaglia, Vincenzo; Maglia, Filippo; Anselmi-Tamburini, Umberto


    The diffusion-controlled growth of niobium silicides (NbSi{sub 2} and Nb{sub 5}Si{sub 3}) was studied in Nb/Si and Nb/NbSi{sub 2} bulk diffusion couples annealed at 1200-1350 degree sign C for 2-24 h. Both compounds were found to grow as parallel layers, according to the parabolic rate law. The concept of the integrated diffusion coefficient is used to describe the growth kinetics of the two silicides. The corresponding activation energy is 263 kJ/mol for Nb{sub 5}Si{sub 3} and 304 kJ/mol for NbSi{sub 2}. The activation energy (in eV) scales as 0.98T{sub m}(K)/1000 for Nb{sub 5}Si{sub 3} and as 1.4T{sub m}(K)/1000 for NbSi{sub 2} in agreement with the general behavior observed for many transition metal silicides. The position of the Kirkendall plane inside the Nb{sub 5}Si{sub 3} layer developed in Nb/NbSi{sub 2} couples indicates that, in the present temperature range, the diffusion of Si in Nb{sub 5}Si{sub 3} is considerably faster than that of Nb.

  2. Thermal behavior analysis of PWR fuel during RIA at various fuel burnups using modified theatre code

    Directory of Open Access Journals (Sweden)

    Nawaz Amjad


    Full Text Available The fuel irradiation and burnup causes geometrical and dimensional changes in the fuel rod which affects its thermal resistance and ultimately affects the fuel rod behavior during steady-state and transient conditions. The consistent analysis of fuel rod thermal performance is essential for precise evaluation of reactor safety in operational transients and accidents. In this work, analysis of PWR fuel rod thermal performance is carried out under steady-state and transient conditions at different fuel burnups. The analysis is performed by using thermal hydraulic code, THEATRe. The code is modified by adding burnup dependent fuel rod behavior models. The original code uses as-fabricated fuel rod dimensions during steady-state and transient conditions which can be modified to perform more consistent reactor safety analysis. AP1000 reactor is considered as a reference reactor for this analysis. The effect of burnup on steady-state fuel rod parameters has been investigated. For transient analysis, hypothetical reactivity initiated accident was simulated by considering a triangular power pulse of variable pulse height (relative to the full power reactor operating conditions and pulse width at different fuel burnups which corresponds to fresh fuel, low and medium burnup fuels. The effect of power pulse height, pulse width and fuel burnup on fuel rod temperatures has been investigated. The results of reactivity initiated accident analysis show that the fuel failure mechanisms are different for fresh fuel and fuel at different burnup levels. The fuel failure in fresh fuel is expected due to fuel melting as fuel temperature increases with increase in pulse energy (pulse height. However, at relatively higher burnups, the fuel failure is expected due to cladding failure caused by strong pellet clad mechanical interaction, where, the contact pressure increases beyond the cladding yield strength.

  3. Tuning magnetic response of epitaxial iron-silicide nanoislands by controlled self-assembled growth (United States)

    Goldfarb, I.; Camus, Y.; Dascalu, M.; Cesura, F.; Chalasani, R.; Kohn, A.


    We investigated the dependence of the magnetic response from epitaxial Si-rich iron-silicide nanostructures on their geometry. By varying substrate orientation and deposition parameters, we altered the growth kinetics and the lattice matching conditions at the silicide/silicon interface. These affected the silicide nanoisland crystal structure, size, shape, and proximity due to spatial ordering and, consequently, their magnetic response in terms of shape and opening of the respective hysteresis loops. In particular, we demonstrated correlation between magnetic anisotropy, expressed as the hysteresis coercive field, and the nanoisland spatial length-to-width aspect ratio. This correlation is explained by the contribution of undercoordinated island edge atoms to the overall measured magnetic behavior of the nanoisland arrays. Further, the island self-ordering along periodic surface steps adds dipolar interactions between the otherwise superparamagnetic nanoislands, consequently resulting in a magnetic response resembling that of a superspin glass.

  4. Silicides: Materials for thermoelectric energy conversion (United States)

    Fedorov, Mikhail I.; Isachenko, Grigory N.


    There are few silicides that could be used for thermoelectric energy conversion, following higher silicides of transition metals: CrSi2, MnSi1.75, β-FeSi2, Ru2Si3, ReSi1.75, and solid solutions based on compounds of Mg2X (X = Si, Ge, and Sn). Some of them have very high figures of merit (ZT). It can be shown that, in some silicides, a high ZT is the result of energy spectrum optimization besides the decrease in thermal conductivity. This is very difficult to achieve in some materials, because the density of states is typically dependent only on the band structure of a material, for which there is no means to produce such a change. However, in solid solutions, if they have a special band structure of components, it is possible to alter the band structure to increase ZT.

  5. Steady-state fuel behavior modeling of nitride fuels in FRAPCON-EP (United States)

    Feng, Bo; Karahan, Aydın; Kazimi, Mujid S.


    Fuel material properties and mechanistic fission gas models in FRAPCON-EP were updated to model the steady-state behavior of high-porosity nitride fuel operating at temperatures below half of the melting point. The fuel thermal conductivity and fuel thermal expansion models were updated with correlations for UN and (U,Pu)N fuels. Hot-pressing of the as-fabricated porosity was modeled as a function of the hydrostatic pressure and creep rate. The solid fission product swelling was assumed to increase linearly with burnup. Fission gas swelling constitutive models were updated to appropriately capture the intragranular gas bubble evolution in nitride fuel. Intergranular gas swelling was neglected due to the assumed high porosity of the fuel. The fission gas release behavior was modeled by fitting the fission gas diffusion coefficient in UN to FRAPCON's default fission gas release model. This fitted gas diffusion coefficient reflects the effects of porosity, burnup, operating temperature, fission rate, and bubble sink strength. Fission gas release and fuel swelling benchmarks against irradiation data were performed. The updated code was applied to UN fuel in typical PWR geometry and operating conditions, with an extended cycle length of 24 months. The results show that swelling of the nitride fuel up to 60 MWd/kg burnup did not lead to excessive straining of the cladding. Furthermore, this study showed that a porous (>15% porosity) nitride fuel pellet could achieve a much higher margin to failure from the cladding collapse and grid-to-rod fretting.

  6. Standard fire behavior fuel models: a comprehensive set for use with Rothermel's surface fire spread model (United States)

    Joe H. Scott; Robert E. Burgan


    This report describes a new set of standard fire behavior fuel models for use with Rothermel's surface fire spread model and the relationship of the new set to the original set of 13 fire behavior fuel models. To assist with transition to using the new fuel models, a fuel model selection guide, fuel model crosswalk, and set of fuel model photos are provided.

  7. Synthesis and design of silicide intermetallic materials

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; Castro, R.G.; Butt, D.P. [Los Alamos National Lab., NM (United States)] [and others


    The overall objective of this program is to develop structural silicide-based materials with optimum combinations of elevated temperature strength/creep resistance, low temperature fracture toughness, and high temperature oxidation and corrosion resistance for applications of importance to the U.S. processing industry. A further objective is to develop silicide-based prototype industrial components. The ultimate aim of the program is to work with industry to transfer the structural silicide materials technology to the private sector in order to promote international competitiveness in the area of advanced high temperature materials and important applications in major energy-intensive U.S. processing industries. The program presently has a number of developing industrial connections, including a CRADA with Schuller International Inc. targeted at the area of MoSi{sub 2}-based high temperature materials and components for fiberglass melting and processing applications. The authors are also developing an interaction with the Institute of Gas Technology (IGT) to develop silicides for high temperature radiant gas burner applications, for the glass and other industries. Current experimental emphasis is on the development and characterization of MoSi{sub 2}-Si{sub 3}N{sub 4} and MoSi{sub 2}-SiC composites, the plasma spraying of MoSi{sub 2}-based materials, and the joining of MoSi{sub 2} materials to metals.

  8. Novel Accident-Tolerant Fuel Meat and Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Robert D. Mariani; Pavel G Medvedev; Douglas L Porter; Steven L Hayes; James I. Cole; Xian-Ming Bai


    A novel accident-tolerant fuel meat and cladding are here proposed. The fuel meat design incorporates annular fuel with inserts and discs that are fabricated from a material having high thermal conductivity, for example niobium. The inserts are rods or tubes. Discs separate the fuel pellets. Using the BISON fuel performance code it was found that the peak fuel temperature can be lowered by more than 600 degrees C for one set of conditions with niobium metal as the thermal conductor. In addition to improved safety margin, several advantages are expected from the lower temperature such as decreased fission gas release and fuel cracking. Advantages and disadvantages are discussed. An enrichment of only 7.5% fully compensates the lost reactivity of the displaced UO2. Slightly higher enrichments, such as 9%, allow uprates and increased burnups to offset the initial costs for retooling. The design has applications for fast reactors and transuranic burning, which may accelerate its development. A zirconium silicide coating is also described for accident tolerant applications. A self-limiting degradation behavior for this coating is expected to produce a glassy, self-healing layer that becomes more protective at elevated temperature, with some similarities to MoSi2 and other silicides. Both the fuel and coating may benefit from the existing technology infrastructure and the associated wide expertise for a more rapid development in comparison to other, more novel fuels and cladding.

  9. Thermal-mechanical behavior of fuel element in SCWR design

    Energy Technology Data Exchange (ETDEWEB)

    Xu, R.; Yetisir, M.; Hamilton, H. [Atomic Energy of Canada Limited, Chalk River, ON (Canada)


    This paper presents a study on thermal-mechanical behavior of a fuel element proposed for the Canadian Supercritical Water Cooled Reactor (SCWR). In the Canadian SCWR, the coolant pressure is 25 MPa, and the temperature is 350{sup o}C at the inlet and 625{sup o}C at the outlet of the reactor core. Critical design decisions for fuel design will be the selection of the fuel sheath material and details of the fuel element design options (sheath thickness, pellet-clad gap, internal pressure, etc.). The analysis presented in this paper predicted temperature, stress and strain in the fuel element of the Canadian SCWR with a collapsible sheath using ANSYS. Typical conditions for the evaluation of the fuel behavior, such as linear heat generation rate, coolant temperature and sheath surface heat transfer coefficient, were extracted from core and fuel channel designs. The temperature distribution in the fuel element is predicted by a thermal model and then the thermal model is coupled sequentially with a structural model to predict fuel sheath deformation under the predicted temperature distribution and external (coolant) pressure. Nonlinear thermo-mechanical simulations include nonlinear buckling with elastic-plastic deformation. Three sheath collapse phenomena are considered: (1) elastic collapse by buckling, (2) longitudinal ridging and (3) plastic collapse by yielding. The numerical models are validated against analytical and experimental data. The presented results show the temperature distribution, deformed shape, stress and strain of the fuel element, allowing the designers to select appropriate sheath material and element design options for the SCWR fuel element design. (author)

  10. Fusion silicide coatings for tantalum alloys. (United States)

    Warnock, R. V.; Stetson, A. R.


    Calculation of the performance of fusion silicide coatings under simulated atmospheric reentry conditions to a maximum temperature of 1810 K (2800 F). Both recently developed and commercially available coatings are included. Data are presented on oxidation rate with and without intentional defecting, the influence of the coatings on the ductile-brittle bend transition temperature, and the mechanical properties. Coatings appear capable of affording protection for at least 100 simulated cycles to 2600 F and 63 cycles to 2800 F.

  11. Modeling of the repository behavior of TRISO fuel.

    Energy Technology Data Exchange (ETDEWEB)

    Morris, E. E.; Bauer, T. H.


    This report satisfies Milestone 4295 for Work Package A0403K11. The long-term behavior of TRISO nuclear reactor fuel in a geologic repository is examined in terms of its durability and thermal impact. The TRISO fuel concept, under development at General Atomics[1] involves embedding fissile uranium and/or actinides in a carbonaceous material as shown in Fig. 1. In the concept, fuel kernels containing fissile material are surrounded with a porous carbon buffer and coated with inner and outer pyrocarbon layers separated with a SiC layer. The fuel particles are then imbedded in a graphite compact and the compacts placed in fuel channels drilled in fuel assembly blocks as shown in the lower right-hand corner of the figure. Dimensions are listed in Table 1. Available data on the degradation of the carbonaceous materials in an aqueous environment is reviewed. A model accounting for waste package failure and the resulting degradation of the waste forms is used to evaluate the potential for the long-term sequestration of radionuclides from spent TRISO fuel in the Yucca Mountain Repository. Finally, thermal analyses of decay heat assess the potential benefits in repository space utilization from recycling actinides from PWR spent fuel as very high burnup TRISO fuel. Experimental data on the aqueous dissolution of carbonaceous materials is relatively sparse and in some cases is based on measurements carried out at temperatures much higher than would be expected in the repository. In addition, the degree to which the aqueous solutions used in the measurements are representative of Yucca Mountain groundwater is uncertain. However, the available dissolution rate data are generally two or more orders of magnitude lower than the Yucca Mountain Project's dissolution model for borosilicate glass. Model calculations show that if the observed rates are applicable to the Yucca Mountain environment, directly disposed TRISO fuel has the potential to prevent significant release of


    Energy Technology Data Exchange (ETDEWEB)

    R. L. Williamson; J. D. Hales; S. R. Novascone; M. R. Tonks; D. R. Gaston; C. J. Permann; D. Andrs; R. C. Martineau


    Important aspects of fuel rod behavior, for example pellet-clad mechanical interaction (PCMI), fuel fracture, oxide formation, non-axisymmetric cooling, and response to fuel manufacturing defects, are inherently multidimensional in addition to being complicated multiphysics problems. Many current modeling tools are strictly 2D axisymmetric or even 1.5D. This paper outlines the capabilities of a new fuel modeling tool able to analyze either 2D axisymmetric or fully 3D models. These capabilities include temperature-dependent thermal conductivity of fuel; swelling and densification; fuel creep; pellet fracture; fission gas release; cladding creep; irradiation growth; and gap mechanics (contact and gap heat transfer). The need for multiphysics, multidimensional modeling is then demonstrated through a discussion of results for a set of example problems. The first, a 10-pellet rodlet, demonstrates the viability of the solution method employed. This example highlights the effect of our smeared cracking model and also shows the multidimensional nature of discrete fuel pellet modeling. The second example relies on our the multidimensional, multiphysics approach to analyze a missing pellet surface problem. As a final example, we show a lower-length-scale simulation coupled to a continuum-scale simulation.

  13. Fabrication and Gas-Sensing Properties of Ni-Silicide/Si Nanowires


    Hsu, Hsun-Feng; Chen, Chun-An; Liu, Shang-Wu; Tang, Chun-Kai


    Ni-silicide/Si nanowires were fabricated by atomic force microscope nano-oxidation on silicon-on-insulator substrates, selective wet etching, and reactive deposition epitaxy. Ni-silicide nanocrystal-modified Si nanowire and Ni-silicide/Si heterostructure multi-stacked nanowire were formed by low- and high-coverage depositions of Ni, respectively. The Ni-silicide/Si Schottky junction and Ni-silicide region were attributed high- and low-resistance parts of nanowire, respectively, causing the re...

  14. Standard guide for drying behavior of spent nuclear fuel

    CERN Document Server

    American Society for Testing and Materials. Philadelphia


    1.1 This guide is organized to discuss the three major components of significance in the drying behavior of spent nuclear fuel: evaluating the need for drying, drying spent nuclear fuel, and confirmation of adequate dryness. 1.1.1 The guide addresses drying methods and their limitations in drying spent nuclear fuels that have been in storage at water pools. The guide discusses sources and forms of water that remain in SNF, its container, or both, after the drying process and discusses the importance and potential effects they may have on fuel integrity, and container materials. The effects of residual water are discussed mechanistically as a function of the container thermal and radiological environment to provide guidance on situations that may require extraordinary drying methods, specialized handling, or other treatments. 1.1.2 The basic issue in drying is to determine how dry the SNF must be in order to prevent issues with fuel retrievability, container pressurization, or container corrosion. Adequate d...

  15. Multi-Dimensional Simulation of LWR Fuel Behavior in the BISON Fuel Performance Code (United States)

    Williamson, R. L.; Capps, N. A.; Liu, W.; Rashid, Y. R.; Wirth, B. D.


    Nuclear fuel operates in an extreme environment that induces complex multiphysics phenomena occurring over distances ranging from inter-atomic spacing to meters, and times scales ranging from microseconds to years. To simulate this behavior requires a wide variety of material models that are often complex and nonlinear. The recently developed BISON code represents a powerful fuel performance simulation tool based on its material and physical behavior capabilities, finite-element versatility of spatial representation, and use of parallel computing. The code can operate in full three dimensional (3D) mode, as well as in reduced two dimensional (2D) modes, e.g., axisymmetric radial-axial ( R- Z) or plane radial-circumferential ( R- θ), to suit the application and to allow treatment of global and local effects. A BISON case study was used to illustrate analysis of Pellet Clad Mechanical Interaction failures from manufacturing defects using combined 2D and 3D analyses. The analysis involved commercial fuel rods and demonstrated successful computation of metrics of interest to fuel failures, including cladding peak hoop stress and strain energy density. In comparison with a failure threshold derived from power ramp tests, results corroborate industry analyses of the root cause of the pellet-clad interaction failures and illustrate the importance of modeling 3D local effects around fuel pellet defects, which can produce complex effects including cold spots in the cladding, stress concentrations, and hot spots in the fuel that can lead to enhanced cladding degradation such as hydriding, oxidation, CRUD formation, and stress corrosion cracking.

  16. Thermoelectric properties of group VI metal silicide semiconductors (United States)

    Nonomura, T.; Wen, C.; Kato, A.; Isobe, K.; Kubota, Y.; Nakamura, T.; Yamashita, M.; Hayakawa, Y.; Tatsuoka, H.

    The electrical and thermoelectric properties of group VI metal silicides, such as the Mo- and W-silicides as well as CrSi2, were investigated. The electronic band structures of the hexagonal- MoSi2, - WSi2 and CrSi2, were calculated using the first-principles total-energy calculation program in pseudopotential schemes with plane-wave basis functions, and their Seebeck coefficients were also calculated. In addition, the Mo- and W-silicides were synthesized using mechanical alloying followed by a spark plasma sintering technique, and their structural, electric and thermoelectric properties were examined.

  17. Performance of fire behavior fuel models developed for the Rothermel Surface Fire Spread Model (United States)

    Robert Ziel; W. Matt Jolly


    In 2005, 40 new fire behavior fuel models were published for use with the Rothermel Surface Fire Spread Model. These new models are intended to augment the original 13 developed in 1972 and 1976. As a compiled set of quantitative fuel descriptions that serve as input to the Rothermel model, the selected fire behavior fuel model has always been critical to the resulting...

  18. Behavior of iodine in the dissolution of spent nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, Tsutomu; Komatsu, Kazunori; Takahashi, A. [Japan Atomic Energy Research Institute, Ibaraki-ken (Japan)


    The results of laboratory-scale experiments concerning the behavior of iodine in the dissolution of spent nuclear fuels, which were carried out at the Japan Atomic Energy Research Institute, are summarized. Based on previous and new experimental results, the difference in quantity of residual iodine in the fuel solution between laboratory-scale experiments and reprocessing plants is discussed, Iodine in spent fuels is converted to the following four states: (1) oxidation into I{sub 2} by nitric acid, (2) oxidation into I{sub 2} by nitrous acid generated in the dissolution, (3) formation of a colloid of insoluble iodides such as AgI and PdI{sub 2}, and (4) deposition on insoluble residue. Nitrous acid controls the amount of colloid formed. As a result, up to 10% of iodine in spent fuels is retained in the fuel solution, up to 3% is deposited on insoluble residue, and the balance volatilizes to the off-gas, Contrary to earlier belief, when the dissolution is carried out in 3 to 4 M HNO{sub 3} at 100{degrees}C, the main iodine species in a fuel solution is a colloid, not iodate, Immediately after its formation, the colloid is unstable and decomposes partially in the hot nitric acid solution through the following reaction: AgI(s) + 2HNO{sub 3}(aq) = {1/2}I{sub 2}(aq) + AgNO{sub 3}(aq) + NO{sub 2}(g) + H{sub 2}O(1). For high concentrations of gaseous iodine, I{sub 2}(g), and NO{sub 2}, this reaction is reversed towards formation of the colloid (AgI). Since these concentrations are high near the liquid surface of a plant-scale dissolver, there is a possibility that the colloid is formed there through this reversal, Simulations performed in laboratory-scale experiments demonstrated this reversal, This phenomenon can be one reason the quantity of residual iodine in spent fuels is higher in reprocessing plants than in laboratory-scale experiments. 17 refs., 5 figs., 3 tabs.

  19. Thermal transport across metal silicide-silicon interfaces: An experimental comparison between epitaxial and nonepitaxial interfaces (United States)

    Ye, Ning; Feser, Joseph P.; Sadasivam, Sridhar; Fisher, Timothy S.; Wang, Tianshi; Ni, Chaoying; Janotti, Anderson


    Silicides are used extensively in nano- and microdevices due to their low electrical resistivity, low contact resistance to silicon, and their process compatibility. In this work, the thermal interface conductance of TiSi2, CoSi2, NiSi, and PtSi are studied using time-domain thermoreflectance. Exploiting the fact that most silicides formed on Si(111) substrates grow epitaxially, while most silicides on Si(100) do not, we study the effect of epitaxy, and show that for a wide variety of interfaces there is no dependence of interface conductance on the detailed structure of the interface. In particular, there is no difference in the thermal interface conductance between epitaxial and nonepitaxial silicide/silicon interfaces, nor between epitaxial interfaces with different interface orientations. While these silicide-based interfaces yield the highest reported interface conductances of any known interface with silicon, none of the interfaces studied are found to operate close to the phonon radiation limit, indicating that phonon transmission coefficients are nonunity in all cases and yet remain insensitive to interfacial structure. In the case of CoSi2, a comparison is made with detailed computational models using (1) full-dispersion diffuse mismatch modeling (DMM) including the effect of near-interfacial strain, and (2) an atomistic Green' function (AGF) approach that integrates near-interface changes in the interatomic force constants obtained through density functional perturbation theory. Above 100 K, the AGF approach significantly underpredicts interface conductance suggesting that energy transport does not occur purely by coherent transmission of phonons, even for epitaxial interfaces. The full-dispersion DMM closely predicts the experimentally observed interface conductances for CoSi2, NiSi, and TiSi2 interfaces, while it remains an open question whether inelastic scattering, cross-interfacial electron-phonon coupling, or other mechanisms could also account for

  20. An analysis of heating fuel market behavior, 1989--1990

    Energy Technology Data Exchange (ETDEWEB)


    The purpose of this report is to fully assess the heating fuel crisis from a broader and longer-term perspective. Using EIA final, monthly data, in conjunction with credible information from non-government sources, the pricing phenomena exhibited by heating fuels in late December 1989 and early January 1990 are described and evaluated in more detail and more accurately than in the interim report. Additionally, data through February 1990 (and, in some cases, preliminary figures for March) make it possible to assess the market impact of movements in prices and supplies over the heating season as a whole. Finally, the longer time frame and the availability of quarterly reports filed with the Securities and Exchange Commission make it possible to weigh the impact of revenue gains in December and January on overall profits over the two winter quarters. Some of the major, related issues raised during the House and Senate hearings in January concerned the structure of heating fuel markets and the degree to which changes in this structure over the last decade may have influenced the behavior and financial performance of market participants. Have these markets become more concentrated Was collusion or market manipulation behind December's rising prices Did these, or other, factors permit suppliers to realize excessive profits What additional costs were incurred by consumers as a result of such forces These questions, and others, are addressed in the course of this report.

  1. Rare earth silicide nanowires on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Martina


    The growth, structure and electronic properties of rare earth silicide nanowires are investigated on planar and vicinal Si(001) und Si(111) surfaces with scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and angle-resolved photoelectron spectroscopy (ARPES). On all surfaces investigated within this work hexagonal disilicides are grown epitaxially with a lattice mismatch of -2.55% up to +0.83% along the hexagonal a-axis. Along the hexagonal c-axis the lattice mismatch is essentially larger with 6.5%. On the Si(001)2 x 1 surface two types of nanowires are grown epitaxially. The socalled broad wires show a one-dimensional metallic valence band structure with states crossing the Fermi level. Along the nanowires two strongly dispersing states at the anti J point and a strongly dispersing state at the anti {gamma} point can be observed. Along the thin nanowires dispersing states could not be observed. Merely in the direction perpendicular to the wires an intensity variation could be observed, which corresponds to the observed spacial structure of the thin nanowires. The electronic properties of the broad erbium silicide nanowires are very similar to the broad dysprosium silicide nanowires. The electronic properties of the DySi{sub 2}-monolayer and the Dy{sub 3}Si{sub 5}-multilayer on the Si(111) surface are investigated in comparison to the known ErSi{sub 2}/Si(111) and Er{sub 3}Si{sub 5}/Si(111) system. The positions and the energetic locations of the observed band in the surface Brillouin zone will be confirmed for dysprosium. The shape of the electron pockets in the (vector)k {sub parallel} space is elliptical at the anti M points, while the hole pocket at the anti {gamma} point is showing a hexagonal symmetry. On the Si(557) surface the structural and electronic properties depend strongly on the different preparation conditions likewise, in particular on the rare earth coverage. At submonolayer coverage the thin nanowires grow in wide areas

  2. Steady-state thermal hydraulic analysis and flow channel blockage accident analysis of JRR-4 silicide LEU core

    Energy Technology Data Exchange (ETDEWEB)

    Kaminaga, Masanori; Yamamoto, Kazuyoshi; Watanabe, Shukichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    JRR-4 is a light water moderated and cooled, graphite reflected pool type research reactor using high enriched uranium (HEU) plate-type fuels. Its thermal power is 3.5 MW. The core conversion program from HEU fuel to uranium-silicon-aluminum (U{sub 3}Si{sub 2}-Al) dispersion type fuel (Silicide fuel) with low enriched uranium (LEU) is currently conducted at the JRR-4. This report describes about the steady-state thermal hydraulic analysis results and the flow channel blockage accident analysis result. In JRR-4, there are two operation mode. One is high power operation mode up to 3.5 MW, under forced convection cooling using the primary and the secondary cooling systems. The other is low power operation mode up to 200 kW, under natural circulation cooling between the reactor core and the reactor pool without the primary and the secondary cooling systems. For the analysis of the high power operation mode under forced convection cooling and the flow channel blockage accident, COOLOD code was used. On the other hand, for the analysis of low power operation under natural convection cooling, COOLOD-N2 code was used. From steady-state thermal hydraulic analysis results of both forced and natural convection cooling, fuel temperature, minimum DNBR etc. meet the design criteria and JRR-4 LEU silicide core has enough safety margin under normal operation conditions. Furthermore, flow channel blockage accident analysis results show that one channel flow blockage accident meet the safety criteria for accident conditions which have been established for JRR-4 LEU silicide core. (author)

  3. Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael


    Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

  4. Hydrogen generation systems and methods utilizing sodium silicide and sodium silica gel materials (United States)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael


    Systems, devices, and methods combine thermally stable reactant materials and aqueous solutions to generate hydrogen and a non-toxic liquid by-product. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Springs and other pressurization mechanisms pressurize and deliver an aqueous solution to the reaction. A check valve and other pressure regulation mechanisms regulate the pressure of the aqueous solution delivered to the reactant fuel material in the reactor based upon characteristics of the pressurization mechanisms and can regulate the pressure of the delivered aqueous solution as a steady decay associated with the pressurization force. The pressure regulation mechanism can also prevent hydrogen gas from deflecting the pressure regulation mechanism.

  5. Evaluation of Transmission Line Model Structures for Silicide-to-Silicon Specific Contact Resistance Extraction

    NARCIS (Netherlands)

    Stavitski, N.; van Dal, Mark J.H.; Lauwers, Anne; Vrancken, Christa; Kovalgin, Alexeij Y.; Wolters, Robertus A.M.


    In order to measure silicide-to-silicon specific contact resistance �?c, transmission line model (TLM) structures were proposed as attractive candidates for embedding in CMOS processes. We optimized TLM structures for nickel silicide and platinum silicide and evaluated them for various doping levels

  6. High Temperature Silicides and Refractory Alloys Symposium Held in Boston, Massachusetts on November 29 -December 2, 1993. Volume 322 (United States)


    MECHANICAL BEHAVIOR OF Nb-Ti BASE BETA + SILICIDE ALLOYS . ................................... 491 P.R. Subramanian, M.G. Mendiratta, and D.M. Dimiduk...above -1300°C, the amorphous silica can transform to a- cristobalite . The oxygen diffusivity will change as the structure of the silica changes, and...first 10 to 40 hours. After 100 hours of oxidation, the XRD analysis shows that the oxide layer is cristobalite , the stable crystalline phase of silica

  7. Anomalous frequency dependent diamagnetism in metal silicide (United States)

    Dahal, Ashutosh; Gunasekera, Jagat; Harriger, Leland; Singh, David J.; Singh, Deepak K.; Leland Harriger Collaboration

    Discovery of superconductivity in PbO-type FeSe has generated a lot of interest. Among the samples we synthesize with similar structure, NiSi has showed anomalous but very interesting results. Nickel silicides are important electronic materials that have been used as contacts for field effect transistors, as interconnects and in nanoelectronic devices. The magnetic properties of NiSi are not well known, however. In this presentation, we report a highly unusual magnetic phenomenon in NiSi. The ac susceptibility measurements on NiSi reveal strong frequency dependence of static and dynamic susceptibilities that are primarily diamagnetic at room temperature. The static susceptibility is found to exhibit a strong frequency dependence of the diamagnetic response below 100K, while dynamic susceptibility showed peak type feature at 10KHz frequency around 50K. Detailed neutron scattering measurements on high quality powder sample of NiSi on SPINS cold spectrometer further revealed an inelastic peak around 1.5meV, even though no magnetic order is detected. The inelastic peak dissipates above 100K, which is where the static susceptibility starts to diverge with frequency. Research is supported by U.S. Department of Energy, Office of Basic Energy Sciences under Grant No. DE-SC0014461.

  8. Submicron Features in Higher Manganese Silicide

    Directory of Open Access Journals (Sweden)

    Yatir Sadia


    Full Text Available The world energy crisis had increased the demand for alternative energy sources and as such is one of the topics at the forefront of research. One way for reducing energy consumption is by thermoelectricity. Thermoelectric effects enable direct conversion of thermal into electrical energy. Higher manganese silicide (HMS, MnSi1.75 is one of the promising materials for applications in the field of thermoelectricity. The abundance and low cost of the elements, combined with good thermoelectric properties and high mechanical and chemical stability at high temperatures, make it very attractive for thermoelectric applications. Recent studies have shown that Si-rich HMS has improved thermoelectric properties. The most interesting of which is the unusual reduction in thermal conductivity. In the current research, transmission (TEM and scanning (SEM electron microscopy as well as X-ray diffraction methods were applied for investigation of the govern mechanisms resulting in very low thermal conductivity values of an Si-rich HMS composition, following arc melting and hot-pressing procedures. In this paper, it is shown that there is a presence of sub-micron dislocations walls, stacking faults, and silicon and HMS precipitates inside each other apparent in the matrix, following a high temperature (0.9 Tm hot pressing for an hour. These are not just responsible for the low thermal conductivity values observed but also indicate the ability to create complicate nano-structures that will last during the production process and possibly during the application.

  9. Comparative analysis of thermal behavior in hollow nuclear fuel pellets

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Beatriz M. dos; Alvim, Antonio C.M., E-mail:, E-mail: [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (PEN/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear


    The increase in energy demand in Brazil and in the world is a real problem and several solutions are being considered to mitigate it. Maximization of energy generation, within the safety standards of fuel resources already known, is one of them. In this respect, nuclear energy is a crucial technology to sustain energy demand on several countries. Performances of a solid cylindrical and an annular rod have been verified and compared; where it has been proven that the annular rod can reach a higher nominal power in relation to the solid one. In this paper, the temperature profiles of two distinct nuclear fuel pellets, one of them annular and the other in the shape of a hollow biconcave disc (like the cross section of a red blood cell), were compared to analyze the efficiency and safety of both. The finite differences method allowed the evaluation of the thermal behavior of these pellets, where one specific physical condition was analyzed, regarding convection and conduction at the lateral edges. The results show that the temperature profile of the hollow biconcave disc pellet is lower, about 70 deg C below, when compared to the temperature profile of the annular pellet, considering the same simulation parameters for both pellets. (author)

  10. Si-Ge Nano-Structured with Tungsten Silicide Inclusions (United States)

    Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred


    Traditional silicon germanium high temperature thermoelectrics have potential for improvements in figure of merit via nano-structuring with a silicide phase. A second phase of nano-sized silicides can theoretically reduce the lattice component of thermal conductivity without significantly reducing the electrical conductivity. However, experimentally achieving such improvements in line with the theory is complicated by factors such as control of silicide size during sintering, dopant segregation, matrix homogeneity, and sintering kinetics. Samples are prepared using powder metallurgy techniques; including mechanochemical alloying via ball milling and spark plasma sintering for densification. In addition to microstructural development, thermal stability of thermoelectric transport properties are reported, as well as couple and device level characterization.

  11. Formation of cobalt silicide by ion beam mixing (United States)

    Min, Ye; Burte, Edmund P.; Ryssel, Heiner


    The formation of cobalt silicides by arsenic ion implantation through a cobalt film which causes a mixing of the metal with the silicon substrate was investigated. Furthermore, cobalt suicides were formed by rapid thermal annealing (RTA). Sheet resistance and silicide phases of implanted Co/Si samples depend on the As dose. Ion beam mixing at doses higher than 5 × 10 15 cm -2 and RTA at temperatures T ⩾ 900° C result in almost equal values of Rs. RBS and XRD spectra of these samples illustrate the formation of a homogeneous CoSi 2 layer. Significant lateral growth of cobalt silicide beyond the edge of patterned SiO 2 was observed in samples which were only subjected to an RTA process ( T ⩾ 900 ° C), while this lateral suicide growth could be reduced efficiently by As implantation prior to RTA.

  12. Ultra Thin Poly-Si Nanosheet Junctionless Field-Effect Transistor with Nickel Silicide Contact. (United States)

    Lin, Yu-Ru; Tsai, Wan-Ting; Wu, Yung-Chun; Lin, Yu-Hsien


    This study demonstrated an ultra thin poly-Si junctionless nanosheet field-effect transistor (JL NS-FET) with nickel silicide contact. For the nickel silicide film, two-step annealing and a Ti capping layer were adopted to form an ultra thin uniform nickel silicide film with low sheet resistance (Rs). The JL NS-FET with nickel silicide contact exhibited favorable electrical properties, including a high driving current (>10⁷A), subthreshold slope (186 mV/dec.), and low parasitic resistance. In addition, this study compared the electrical characteristics of JL NS-FETs with and without nickel silicide contact.

  13. Ultra Thin Poly-Si Nanosheet Junctionless Field-Effect Transistor with Nickel Silicide Contact

    Directory of Open Access Journals (Sweden)

    Yu-Ru Lin


    Full Text Available This study demonstrated an ultra thin poly-Si junctionless nanosheet field-effect transistor (JL NS-FET with nickel silicide contact. For the nickel silicide film, two-step annealing and a Ti capping layer were adopted to form an ultra thin uniform nickel silicide film with low sheet resistance (Rs. The JL NS-FET with nickel silicide contact exhibited favorable electrical properties, including a high driving current (>107A, subthreshold slope (186 mV/dec., and low parasitic resistance. In addition, this study compared the electrical characteristics of JL NS-FETs with and without nickel silicide contact.

  14. Ni and Ni Silicides Ohmic Contacts on N-type 6H-SiC with Medium and Low Doping Level

    Directory of Open Access Journals (Sweden)

    S. Cichon


    Full Text Available Ni silicides contacts, which are expected to be advantageous contact materials on SiC, were tested in this work. Prepared contact structures were ohmic with low contact resistivity approximately 8×10-4 Ω cm2 after annealing at 960°C as far as the SiC substrate with a medium doping level was concerned, no matter whether Ni or Ni silicides were used. At lower annealing temperatures, only Schottky behavior was observed by means of I-V characteristics measurements. In the case of SiC substrate with a low doping level, the behavior differed. It was necessary to anneal the structures at 1070°C to see ohmic behavior appearing with resistivities reaching 8×10-3 Ω cm2 and this was valid only for Ni and Ni2Si. Raman spectroscopy measurements confirmed formation of single Ni silicides as expected. It was found that Ni silicides can keep as good resistivity as Ni contacts while they interact with SiC in limited way and their undesirable drop-like morphology is expected to be overcome for example with a covering layer.

  15. Study of fuel control strategy based on an fuel behavior model for starting conditions; Nenryo kyodo model ni motozuita shidoji no nenryo hosei hosho ni tsuite no kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Y.; Uchida, M.; Iwano, H.; Oba, H. [Nissan Motor Co. Ltd., Tokyo (Japan)


    We have applied a fuel behavior model to a fuel injection system which we call SOFIS (Sophisticated and Optimized Fuel Injection System) so that we get air/fuel ratio control accuracy and good driveability. However the fuel behavior under starting conditions is still not clear. To meet low emission rules and to get better driveability under starting conditions, better air/fuel ratio control is necessary. Now we have understood the ignition timing, injection timing, and injection pulse width required in such conditions. In former days, we analyzed the state of the air/fuel mixture under cold conditions and made a new fuel behavior model which considered fuel loss such as hydrocarbons and dissolution into oil and so on. Al this time, we have applied this idea to starting. We confirm this new model offers improved air/fuel ratio control. 6 refs., 9 figs., 3 tabs.

  16. Introduction-2nd Fire Behavior and Fuels Conference: The fire environment-innovations, management, and policy (United States)

    Wayne Cook; Bret W. Butler


    The 2nd Fire Behavior and Fuels Conference: Fire Environment -- Innovations, Management and Policy was held in Destin, FL, March 26-30, 2007. Following on the success of the 1st Fire Behavior and Fuels Conference, this conference was initiated in response to the needs of the National Wildfire Coordinating Group -- Fire Environment Working Team.

  17. Metallic interconnects for proton ceramic fuel cells : oxidation behavior under simulated fuel cell conditions


    Skilbred, Anders Werner Bredvei


    Fuel cells are expected to serve as a contribution to meet the demand for clean energy. High temperature fuel cells such as solid oxide fuel cells (SOFC) and proton ceramic fuel cells (PCFC) are developed for use as environment friendly energy conversion devices. However, the successful implementation of such devices in practical applications relies on series connections of multiple cells by so-called interconnects. During operation at high temperatures (600 – 850 °C) facing both air and fuel...

  18. Developing Custom Fire Behavior Fuel Models for Mediterranean Wildland-Urban Interfaces in Southern Italy (United States)

    Elia, Mario; Lafortezza, Raffaele; Lovreglio, Raffaella; Sanesi, Giovanni


    The dramatic increase of fire hazard in wildland-urban interfaces (WUIs) has required more detailed fuel management programs to preserve ecosystem functions and human settlements. Designing effective fuel treatment strategies allows to achieve goals such as resilient landscapes, fire-adapted communities, and ecosystem response. Therefore, obtaining background information on forest fuel parameters and fuel accumulation patterns has become an important first step in planning fuel management interventions. Site-specific fuel inventory data enhance the accuracy of fuel management planning and help forest managers in fuel management decision-making. We have customized four fuel models for WUIs in southern Italy, starting from forest classes of land-cover use and adopting a hierarchical clustering approach. Furthermore, we provide a prediction of the potential fire behavior of our customized fuel models using FlamMap 5 under different weather conditions. The results suggest that fuel model IIIP (Mediterranean maquis) has the most severe fire potential for the 95th percentile weather conditions and the least severe potential fire behavior for the 85th percentile weather conditions. This study shows that it is possible to create customized fuel models directly from fuel inventory data. This achievement has broad implications for land managers, particularly forest managers of the Mediterranean landscape, an ecosystem that is susceptible not only to wildfires but also to the increasing human population and man-made infrastructures.

  19. Scratch Behaviors of Cr-Coated Zr-Based Fuel Claddings for Accident-Tolerant Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Ho; Kim, Il-Hyun; Kim, Hyun-Gil; Kim, Hyung-Kyu; Koo, Yang-Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    As the progression of Fukushima accident is worsened by the runaway reaction at a high temperature above 1200 .deg. C, it is essential to ensure the stabilities of coating layers on conventional Zr-based alloys during normal operations as well as severe accident conditions. This is because the failures of coating layer result in galvanic corrosion phenomenon by potential difference between coating layer and Zr alloy. Also, it is possible to damage the coating layer during handling and manufacturing process by contacting structural components of a fuel assembly. So, adhesion strength is one of the key factors determining the reliability of the coating layer on conventional Zr-based alloy. In this study, two kinds of Cr-coated Zr-based claddings were prepared using arc ion plating (AIP) and direct laser (DL) coating methods. The objective is to evaluate the scratch deformation behaviors of each coating layers on Zr alloys. Large area spallation below normal load of about 15 N appeared to be the predominant mode of failure in the AIP coating during scratch test. However, no tensile crack were found in entire stroke length. In DL coating, small plastic deformation and grooving behavior are more dominant scratching results. It was observed that the change of the slope of the COF curve did not coincide with the failure of coating layer.

  20. Reactor Physics Behavior of Transuranic-Bearing TRISO-Particle Fuel in a Pressurized Water Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Michael A. Pope; R. Sonat Sen; Abderrafi M. Ougouag; Gilles Youinou; Brian Boer


    Calculations have been performed to assess the neutronic behavior of pins of Fully-Ceramic Micro-encapsulated (FCM) fuel in otherwise-conventional Pressurized Water Reactor (PWR) fuel pins. The FCM fuel contains transuranic (TRU)-only oxide fuel in tri-isotropic (TRISO) particles with the TRU loading coming from the spent fuel of a conventional LWR after 5 years of cooling. Use of the TRISO particle fuel would provide an additional barrier to fission product release in the event of cladding failure. Depletion calculations were performed to evaluate reactivity-limited burnup of the TRU-only FCM fuel. These calculations showed that due to relatively little space available for fuel, the achievable burnup with these pins alone is quite small. Various reactivity parameters were also evaluated at each burnup step including moderator temperature coefficient (MTC), Doppler, and soluble boron worth. These were compared to reference UO{sub 2} and MOX unit cells. The TRU-only FCM fuel exhibits degraded MTC and Doppler coefficients relative to UO{sub 2} and MOX. Also, the reactivity effects of coolant voiding suggest that the behavior of this fuel would be similar to a MOX fuel of very high plutonium fraction, which are known to have positive void reactivity. In general, loading of TRU-only FCM fuel into an assembly without significant quantities of uranium presents challenges to the reactor design. However, if such FCM fuel pins are included in a heterogeneous assembly alongside LEU fuel pins, the overall reactivity behavior would be dominated by the uranium pins while attractive TRU destruction performance levels in the TRU-only FCM fuel pins is. From this work, it is concluded that use of heterogeneous assemblies such as these appears feasible from a preliminary reactor physics standpoint.

  1. Silicide Schottky Contacts to Silicon: Screened Pinning at Defect Levels

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, T.J.


    Silicide Schottky contacts can be as large as 0.955 eV (E{sub v} + 0.165 eV) on n-type silicon and as large as 1.05 eV (E{sub c} {minus} 0.07 eV) on p-type silicon. Current models of Schottky barrier formation do not provide a satisfactory explanation of occurrence of this wide variation. A model for understanding Schottky contacts via screened pinning at defect levels is presented. In the present paper it is shown that most transition metal silicides are pinned approximately 0.48 eV above the valence band by interstitial Si clusters. Rare earth disilicides pin close to the divacancy acceptor level 0.41 eV below the conduction band edge while high work function silicides of Ir and Pt pin close to the divacancy donor level 0.21 eV above the valence band edge. Selection of a particular defect pinning level depends strongly on the relative positions of the silicide work function and the defect energy level on an absolute energy scale.

  2. Silicon and silicide nanowires applications, fabrication, and properties

    CERN Document Server

    Tu, King-Ning


    This book comprises theoretical and experimental analysis of various properties of silicon nanocrystals, research methods and preparation techniques, and some promising applications. It comprises nine chapters. The first three are based on processing, the next three on properties, and the last three on applications of nanowires of silicon and silicides.

  3. Spin, Charge, and Bonding in Transition Metal Mono Silicides

    NARCIS (Netherlands)

    Marel, D. van der; Damascelli, A.; Schulte, K.; Menovsky, A. A.


    Published in: Physica B 244 (1998) 138-147 citations recorded in [Science Citation Index] Abstract: We review some of the relevant physical properties of the transition metal mono-silicides with the FeSi structure (CrSi, MnSi, FeSi, CoSi, NiSi, etc) and explore the relation between their structural

  4. Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials (United States)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael


    Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

  5. Hydrogen generation systems utilizing sodium silicide and sodium silica gel materials

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, Andrew P.; Melack, John M.; Lefenfeld, Michael


    Systems, devices, and methods combine reactant materials and aqueous solutions to generate hydrogen. The reactant materials can sodium silicide or sodium silica gel. The hydrogen generation devices are used in fuels cells and other industrial applications. One system combines cooling, pumping, water storage, and other devices to sense and control reactions between reactant materials and aqueous solutions to generate hydrogen. Multiple inlets of varied placement geometries deliver aqueous solution to the reaction. The reactant materials and aqueous solution are churned to control the state of the reaction. The aqueous solution can be recycled and returned to the reaction. One system operates over a range of temperatures and pressures and includes a hydrogen separator, a heat removal mechanism, and state of reaction control devices. The systems, devices, and methods of generating hydrogen provide thermally stable solids, near-instant reaction with the aqueous solutions, and a non-toxic liquid by-product.

  6. Pack cementation Cr-Al coating of steels and Ge-doped silicide coating of Cr-Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    He, Y.R.; Zheng, M.H.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States)


    Carbon steels or low-alloy steels used in utility boilers, heat exchangers, petrochemical plants and coal gasification systems are subjected to high temperature corrosion attack such as oxidation, sulfidation and hot corrosion. The pack cementation coating process has proven to be an economical and effective method to enhance the corrosion resistance by modifying the surface composition of steels. With the aid of a computer program, STEPSOL, pack cementation conditions to produce a ferrite Cr-Al diffusion coating on carbon-containing steels by using elemental Cr and Al powders have been calculated and experimentally verified. The cyclic oxidation kinetics for the Cr-Al coated steels are presented. Chromium silicide can maintain high oxidation resistance up to 1100{degrees}C by forming a SiO{sub 2} protective scale. Previous studies at Ohio State University have shown that the cyclic oxidation resistance of MOSi{sub 2} and TiSi{sub 2} can be further improved by Ge addition introduced during coating growth. The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating in a single processing step for the ORNL-developed Cr-Nb advanced intermetallic alloy. The oxidation behavior of the silicide-coated Cr-Nb alloy was excellent: weight gain of about 1 mg/cm{sup 2} upon oxidation at 1100{degrees}C in air for 100 hours.

  7. Texture in thin film silicides and germanides: A review

    Energy Technology Data Exchange (ETDEWEB)

    De Schutter, B., E-mail:; De Keyser, K.; Detavernier, C. [Department of Solid State Sciences, Ghent University, Ghent (Belgium); Lavoie, C. [IBM Research Division, T.J. Watson Research Center, P.O. Box 218, Yorktown Heights, New York 10598 (United States)


    Silicides and germanides are compounds consisting of a metal and silicon or germanium. In the microelectronics industry, silicides are the material of choice for contacting silicon based devices (over the years, CoSi{sub 2}, C54-TiSi{sub 2}, and NiSi have been adopted), while germanides are considered as a top candidate for contacting future germanium based electronics. Since also strain engineering through the use of Si{sub 1−x}Ge{sub x} in the source/drain/gate regions of MOSFET devices is an important technique for improving device characteristics in modern Si-based microelectronics industry, a profound understanding of the formation of silicide/germanide contacts to silicon and germanium is of utmost importance. The crystallographic texture of these films, which is defined as the statistical distribution of the orientation of the grains in the film, has been the subject of scientific studies since the 1970s. Different types of texture like epitaxy, axiotaxy, fiber, or combinations thereof have been observed in such films. In recent years, it has become increasingly clear that film texture can have a profound influence on the formation and stability of silicide/germanide contacts, as it controls the type and orientation of grain boundaries (affecting diffusion and agglomeration) and the interface energy (affecting nucleation during the solid-state reaction). Furthermore, the texture also has an impact on the electrical characteristics of the contact, as the orientation and size of individual grains influences functional properties such as contact resistance and sheet resistance and will induce local variations in strain and Schottky barrier height. This review aims to give a comprehensive overview of the scientific work that has been published in the field of texture studies on thin film silicide/germanide contacts.

  8. Preparation and properties of sputtered nitrogen-doped cobalt silicide film

    Energy Technology Data Exchange (ETDEWEB)

    Ting, J.-H.; Shiau, S.-H.; Chen, Y.-J.; Pan, F.-M.; Wong Harianto; Pu, Gibson M.; Kung, C.-Y


    It is the purpose of this study to develop tough hinge material for the application of the torsional springs. Nitrogen-doped cobalt silicide (CoSi{sub x}N{sub y}) film is sputtered from cobalt silicide (CoSi{sub 2}) target in Ar/N{sub 2} discharge. Stress and sheet resistance of CoSi{sub x}N{sub y} film are two major properties to be evaluated. Taguchi method is practiced in reactive sputtering deposition of CoSi{sub x}N{sub y} film. Process pressure is most critical to the CoSi{sub x}N{sub y} film stress and the optimum condition of 1000 W, 0.8 Pa, and 20% N{sub 2} flow ratio, indeed results in low tensile CoSi{sub x}N{sub y} film stress, about 54. MPa. Reannealing process indicates that stability of CoSi{sub x}N{sub y} film is attained after first annealing process. Stress hysteresis behaviors of CoSi{sub x} and CoSi{sub x}N{sub y} films resemble that of metal film with a complete elastic manner in the second stage of heating and cooling. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses suggest that toughness and strength of the film is achievable. It is concluded that CoSi{sub x}N{sub y} film as a hinge material is feasible.

  9. Integrating Fire Behavior Models and Geospatial Analysis for Wildland Fire Risk Assessment and Fuel Management Planning

    Directory of Open Access Journals (Sweden)

    Alan A. Ager


    Full Text Available Wildland fire risk assessment and fuel management planning on federal lands in the US are complex problems that require state-of-the-art fire behavior modeling and intensive geospatial analyses. Fuel management is a particularly complicated process where the benefits and potential impacts of fuel treatments must be demonstrated in the context of land management goals and public expectations. A number of fire behavior metrics, including fire spread, intensity, likelihood, and ecological risk must be analyzed for multiple treatment alternatives. The effect of treatments on wildfire impacts must be considered at multiple scales. The process is complicated by the lack of data integration among fire behavior models, and weak linkages to geographic information systems, corporate data, and desktop office software. This paper describes our efforts to build a streamlined fuel management planning and risk assessment framework, and an integrated system of tools for designing and testing fuel treatment programs on fire-prone wildlands.

  10. Validation of BEHAVE fire behavior predictions in oak savannas using five fuel models (United States)

    Keith Grabner; John Dwyer; Bruce Cutter


    Prescribed fire is a valuable tool in the restoration and management of oak savannas. BEHAVE, a fire behavior prediction system developed by the United States Forest Service, can be a useful tool when managing oak savannas with prescribed fire. BEHAVE predictions of fire rate-of-spread and flame length were validated using four standardized fuel models: Fuel Model 1 (...


    Directory of Open Access Journals (Sweden)

    H.J. RYU


    Full Text Available Since 2001, a series of five irradiation test campaigns for atomized U-Mo dispersion fuel rods, KOMO-1, -2, -3, -4, and -5, has been conducted at HANARO (Korea in order to develop high performance low enriched uranium dispersion fuel for research reactors. The KOMO irradiation tests provided valuable information on the irradiation behavior of U-Mo fuel that results from the distinct fuel design and irradiation conditions of the rod fuel for HANARO. Full size U-Mo dispersion fuel rods of 4–5 g-U/cm3 were irradiated at a maximum linear power of approximately 105 kW/m up to 85% of the initial U-235 depletion burnup without breakaway swelling or fuel cladding failure. Electron probe microanalyses of the irradiated samples showed localized distribution of the silicon that was added in the matrix during fuel fabrication and confirmed its beneficial effect on interaction layer growth during irradiation. The modifications of U-Mo fuel particles by the addition of a ternary alloying element (Ti or Zr, additional protective coatings (silicide or nitride, and the use of larger fuel particles resulted in significantly reduced interaction layers between fuel particles and Al.

  12. Gas cluster ion beam assisted NiPt germano-silicide formation on SiGe

    Energy Technology Data Exchange (ETDEWEB)

    Ozcan, Ahmet S., E-mail: [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Lavoie, Christian; Jordan-Sweet, Jean [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598 (United States); Alptekin, Emre; Zhu, Frank [IBM Semiconductor Research and Development Center, 2070 Route 52, Hopewell Junction, New York 12533 (United States); Leith, Allen; Pfeifer, Brian D.; LaRose, J. D.; Russell, N. M. [TEL Epion Inc., 900 Middlesex Turnpike, Bldg. 6, Billerica, Massachusetts 01821 (United States)


    We report the formation of very uniform and smooth Ni(Pt)Si on epitaxially grown SiGe using Si gas cluster ion beam treatment after metal-rich silicide formation. The gas cluster ion implantation process was optimized to infuse Si into the metal-rich silicide layer and lowered the NiSi nucleation temperature significantly according to in situ X-ray diffraction measurements. This novel method which leads to more uniform films can also be used to control silicide depth in ultra-shallow junctions, especially for high Ge containing devices, where silicidation is problematic as it leads to much rougher interfaces.

  13. Advancements in the behavioral modeling of fuel elements and related structures

    Energy Technology Data Exchange (ETDEWEB)

    Billone, M.C.; Montgomery, R.O.; Rashid, Y.R.; Head, J.L. (Argonne National Lab., IL (USA); ANATECH Research Corp., San Diego, CA (USA); Royal Naval Coll., Greenwich (UK))


    An important aspect of the design and analysis of nuclear reactors is the ability to predict the behavior of fuel elements in the adverse environment of a reactor system. By understanding the thermomechanical behavior of the different materials which constitute a nuclear fuel element, analysis and predictions can be made regarding the integrity and reliability of fuel element designs. The SMiRT conference series, through the division on fuel elements and the post-conference seminars on fuel element modeling, provided technical forums for the international participation in the exchange of knowledge concerning the thermomechanical modeling of fuel elements. This paper discusses the technical advances in the behavioral modeling of fuel elements presented at the SMiRT conference series since its inception in 1971. Progress in the areas of material properties and constitutive relationships, modeling methodologies, and integral modeling approaches was reviewed and is summarized in light of their impact on the thermomechanical modeling of nuclear fuel elements. 34 refs., 5 tabs.

  14. Macroscopic behavior of fast reactor fuel subjected to simulated thermal transients

    Energy Technology Data Exchange (ETDEWEB)

    Fenske, G.R.; Emerson, J.E.; Savoie, F.E.


    High-speed cinematography has been used to characterize the macroscopic behavior of irradiated and unirradiated fuel subjected to thermal transients prototypical of fast reactor transients. The results demonstrate that as the cladding melts, the fuel can disperse via spallation if the fuel contains in excess of approx. 16 of fission gas. Once the cladding has melted, the macroscopic behavior (time to failure and dispersive nature) was strongly influenced by the presence of volatile fission products and the heating rate.

  15. Electronic properties of semiconducting silicides: fundamentals and recent predictions

    Energy Technology Data Exchange (ETDEWEB)

    Ivanenko, L.I.; Shaposhnikov, V.L.; Filonov, A.B.; Krivosheeva, A.V.; Borisenko, V.E.; Migas, D.B.; Miglio, L.; Behr, G.; Schumann, J


    This review emphasizes progress in theoretical simulation and experiments that have been performed in the past years for semiconducting silicides. New fundamental electronic and optical properties of Ca{sub 2}Si and BaSi{sub 2}, recently found RuSi{sub 2} phase, ternaries in Fe-Os-Si and Ru-Os-Si systems, {beta}-FeSi{sub 2}, Mg{sub 2}Si and CrSi{sub 2} with stretched and compressed lattices as well as transport properties of {beta}-FeSi{sub 2}, ReSi{sub 1.75}, Ru{sub 2}Si{sub 3} are presented. Prospects for practical applications of semiconducting silicides are discussed.

  16. Syntheses of Nanostructure Bundles Based on Semiconducting Metal Silicides (United States)

    Li, Wen; Ishikawa, Daisuke; Tatsuoka, Hirokazu


    A variety of nanostructure bundles and arrays based on semiconducting metal silicides have been synthesized using abundant and non-toxic starting materials. Three types of fabrication techniques of the nanostructure bundles or arrays, including direct growth, template synthesis using natural nanostructured materials and template synthesis using artificially fabricated nanostructured materials are demonstrated. CrSi2 nanowire bundles were directly grown by the exposure of Si substrates to CrCl2 vapor at atmospheric pressure. A hexagonal MoSi2 nanosheet, Mg2Si/MgO composite nanowire and Mg2Si nanowire bundles and MnSi1.7 nanowire array were synthesized using a MoS2 layered material, a SiOx nanofiber bundle, a Si nanowire array, and a Si nanowire array as the templates, respectively. Additionally, the fabrication phenomenon and structural properties of the nanostructured semiconducting metal silicides were investigated. These reactions provided the low-cost and controllable synthetic techniques to synthesize large scale and one-dimensional semiconducting metal silicides for thermoelectric applications.

  17. The influence of fuels treatment and landscape arrangement on simulated fire behavior, southern Cascade Range, California (United States)

    David A. Schmidt; Alan H. Taylor; Carl N. Skinner


    Wildfire behavior can be modified by altering the quantity, structure, and arrangement of fuel (flammable vegetation) by silvicultural treatments such as forest thinning and prescribed burning. The type and arrangement (including landscape location) of treated areas have been demonstrated to influence wildfire behavior. This study analyzes the response of several key...

  18. Does habitual behavior affect the choice of alternative fuel vehicles?

    DEFF Research Database (Denmark)

    Valeri, Eva; Cherchi, Elisabetta


    Because of the recent improvements in the electrification process of cars, several types of alternative fuel vehicles are appearing in the car market. However, these new engine technologies are not easily penetrating the market around the world and the conventional ones are still the leaders. A v...

  19. Understanding and Improving High-Temperature Structural Properties of Metal-Silicide Intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Bruce S. Kang


    The objective of this project was to understand and improve high-temperature structural properties of metal-silicide intermetallic alloys. Through research collaboration between the research team at West Virginia University (WVU) and Dr. J.H. Schneibel at Oak Ridge National Laboratory (ORNL), molybdenum silicide alloys were developed at ORNL and evaluated at WVU through atomistic modeling analyses, thermo-mechanical tests, and metallurgical studies. In this study, molybdenum-based alloys were ductilized by dispersing MgAl2O4 or MgO spinel particles. The addition of spinel particles is hypothesized to getter impurities such as oxygen and nitrogen from the alloy matrix with the result of ductility improvement. The introduction of fine dispersions has also been postulated to improve ductility by acting as a dislocation source or reducing dislocation pile-ups at grain boundaries. The spinel particles, on the other hand, can also act as local notches or crack initiation sites, which is detrimental to the alloy mechanical properties. Optimization of material processing condition is important to develop the desirable molybdenum alloys with sufficient room-temperature ductility. Atomistic analyses were conducted to further understand the mechanism of ductility improvement of the molybdenum alloys and the results showed that trace amount of residual oxygen may be responsible for the brittle behavior of the as-cast Mo alloys. For the alloys studied, uniaxial tensile tests were conducted at different loading rates, and at room and elevated temperatures. Thermal cycling effect on the mechanical properties was also studied. Tensile tests for specimens subjected to either ten or twenty thermal cycles were conducted. For each test, a follow-up detailed fractography and microstructural analysis were carried out. The test results were correlated to the size, density, distribution of the spinel particles and processing time. Thermal expansion tests were carried out using thermo

  20. Mechanical behavior of fast reactor fuel pin cladding subjected to simulated overpower transients

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, G.D.; Hunter, C.W.


    Cladding mechanical property data for analysis and prediction of fuel pin transient behavior were obtained under experimental conditions in which the temperature ramps of reactor transients were simulated. All cladding specimens were 20% CW Type 316 stainless steel and were cut from EBR-II irradiated fuel pins. It was determined that irradiation degraded the cladding ductility and failure strength. Specimens that had been adjacent to the fuel exhibited the poorest properties. Correlations were developed to describe the effect of neutron fluence on the mechanical behavior of the cladding. Metallographic examinations were conducted to characterize the failure mode and to establish the nature of internal and external surface corrosion. Various mechanisms for the fuel adjacency effect were examined and results for helium concentration profiles were presented. Results from the simulated transient tests were compared with TREAT test results.

  1. Mechanoactivation of chromium silicide formation in the SiC-Cr-Si system

    Directory of Open Access Journals (Sweden)

    Vlasova M.


    Full Text Available The processes of simultaneous grinding of the components of a SiC-Cr-Si mixture and further temperature treatment in the temperature range 1073-1793 K were studied by X-ray phase analysis, IR spectroscopy, electron microscopy, and X-ray microanalysis. It was established that, during grinding of the mixture, chromium silicides form. A temperature treatment completes the process. Silicide formation proceeds within the framework of the diffusion of silicon into chromium. In the presence of SiO2 in the mixture, silicide formation occurs also as a result of the reduction of silica by silicon and silicon carbide. The sintering of synthesized composite SiC-chromium silicides powders at a high temperature under a high pressure (T = 2073 K, P = 5 GPa is accompanied by the destruction of cc-SiC particles, the cc/3 transition in silicon carbide and deformation distortions of the lattices of chromium silicides.

  2. Behavior of actinides in the Integral Fast Reactor fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, J.C. [Louisiana State Univ., Baton Rouge, LA (United States). Nuclear Science Center; Lineberry, M.J. [Argonne National Lab., Idaho Falls, ID (United States). Technology Development Div.


    The Integral Fast Reactor (IFR) under development by Argonne National Laboratory uses metallic fuels instead of ceramics. This allows electrorefining of spent fuels and presents opportunities for recycling minor actinide elements. Four minor actinides ({sup 237}Np, {sup 240}Pu, {sup 241}Am, and {sup 243}Am) determine the waste storage requirements of spent fuel from all types of fission reactors. These nuclides behave the same as uranium and other plutonium isotopes in electrorefining, so they can be recycled back to the reactor without elaborate chemical processing. An experiment has been designed to demonstrate the effectiveness of the high-energy neutron spectra of the IFR in consuming these four nuclides and plutonium. Eighteen sets of seven actinide and five light metal targets have been selected for ten day exposure in the Experimental Breeder Reactor-2 which serves as a prototype of the IFR. Post-irradiation analyses of the exposed targets by gamma, alpha, and mass spectroscopy are used to determine nuclear reaction-rates and neutron spectra. These experimental data increase the authors` confidence in their ability to predict reaction rates in candidate IFR designs using a variety of neutron transport and diffusion programs.

  3. Analysis of Ignition Behavior in a Turbocharged Direct Injection Dual Fuel Engine Using Propane and Methane as Primary Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Polk, A. C.; Gibson, C. M.; Shoemaker, N. T.; Srinivasan, K. K.; Krishnan, S. R.


    This paper presents experimental analyses of the ignition delay (ID) behavior for diesel-ignited propane and diesel-ignited methane dual fuel combustion. Two sets of experiments were performed at a constant speed (1800 rev/min) using a 4-cylinder direct injection diesel engine with the stock ECU and a wastegated turbocharger. First, the effects of fuel-air equivalence ratios (© pilot ¼ 0.2-0.6 and © overall ¼ 0.2-0.9) on IDs were quantified. Second, the effects of gaseous fuel percent energy substitution (PES) and brake mean effective pressure (BMEP) (from 2.5 to 10 bar) on IDs were investigated. With constant © pilot (> 0.5), increasing © overall with propane initially decreased ID but eventually led to premature propane autoignition; however, the corresponding effects with methane were relatively minor. Cyclic variations in the start of combustion (SOC) increased with increasing © overall (at constant © pilot), more significantly for propane than for methane. With increasing PES at constant BMEP, the ID showed a nonlinear (initially increasing and later decreasing) trend at low BMEPs for propane but a linearly decreasing trend at high BMEPs. For methane, increasing PES only increased IDs at all BMEPs. At low BMEPs, increasing PES led to significantly higher cyclic SOC variations and SOC advancement for both propane and methane. Finally, the engine ignition delay (EID) was also shown to be a useful metric to understand the influence of ID on dual fuel combustion.

  4. Comparison of Material Behavior of Matrix Graphite for HTGR Fuel Elements upon Irradiation: A literature Survey

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Woo; Yeo, Seunghwan; Cho, Moon Sung [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    The fuel elements for the HTGRs (i.e., spherical fuel element in pebble-bed type core design and fuel compact in prismatic core design) consists of coated fuel particles dispersed and bonded in a closely packed array within a carbonaceous matrix. This matrix is generally made by mixing fully graphitized natural and needle- or pitchcoke originated powders admixed with a binder material (pitch or phenolic resin), The resulting resinated graphite powder mixture, when compacted, may influence a number of material properties as well as its behavior under neutron irradiation during reactor operation. In the fabrication routes of these two different fuel element forms, different consolidation methods are employed; a quasi-isostatic pressing method is generally adopted to make pebbles while fuel compacts are fabricated by uni-axial pressing mode. The result showed that the hardness values obtained from the two directions showed an anisotropic behavior: The values obtained from the perpendicular section showed much higher micro hardness (176.6±10.5MPa in average) than from the parallel section ((125.6±MPa in average). This anisotropic behavior was concluded to be related to the microstructure of the matrix graphite. This may imply that the uni-axial pressing method to make compacts influence the microstructure of the matrix and hence the material properties of the matrix graphite.

  5. A comparison of geospatially modeled fire behavior and potential application to fire and fuels management for the Savannah River Site.

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, Laurie; Hollingsworth, LaWen; Shea, Dan


    This study evaluates modeled fire behavior for the Savannah River Site in the Atlantic Coastal Plain of the southeastern U.S. using three data sources: FCCS, LANDFIRE, and SWRA. The Fuel Characteristic Classification System (FCCS) was used to build fuelbeds from intensive field sampling of 629 plots. Custom fire behavior fuel models were derived from these fuelbeds. LANDFIRE developed surface fire behavior fuel models and canopy attributes for the U.S. using satellite imagery informed by field data. The Southern Wildfire Risk Assessment (SWRA) developed surface fire behavior fuel models and canopy cover for the southeastern U.S. using satellite imagery.

  6. Preliminary Modeling of Accident Tolerant Fuel Concepts under Accident Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle A.; Hales, Jason D.


    The catastrophic events that occurred at the Fukushima-Daiichi nuclear power plant in 2011 have led to widespread interest in research of alternative fuels and claddings that are proposed to be accident tolerant. Thus, the United States Department of Energy through its NEAMS (Nuclear Energy Advanced Modeling and Simulation) program has funded an Accident Tolerant Fuel (ATF) High Impact Problem (HIP). The ATF HIP is funded for a three-year period. The purpose of the HIP is to perform research into two potential accident tolerant concepts and provide an in-depth report to the Advanced Fuels Campaign (AFC) describing the behavior of the concepts, both of which are being considered for inclusion in a lead test assembly scheduled for placement into a commercial reactor in 2022. The initial focus of the HIP is on uranium silicide fuel and iron-chromium-aluminum (FeCrAl) alloy cladding. Utilizing the expertise of three national laboratory participants (INL, LANL, and ANL) a comprehensive mulitscale approach to modeling is being used including atomistic modeling, molecular dynamics, rate theory, phase-field, and fuel performance simulations. In this paper, we present simulations of two proposed accident tolerant fuel systems: U3Si2 fuel with Zircaloy-4 cladding, and UO2 fuel with FeCrAl cladding. The simulations investigate the fuel performance response of the proposed ATF systems under Loss of Coolant and Station Blackout conditions using the BISON code. Sensitivity analyses are completed using Sandia National Laboratories’ DAKOTA software to determine which input parameters (e.g., fuel specific heat) have the greatest influence on the output metrics of interest (e.g., fuel centerline temperature). Early results indicate that each concept has significant advantages as well as areas of concern. Further work is required prior to formulating the proposition report for the Advanced Fuels Campaign.

  7. Investigations into the low temperature behavior of jet fuels: Visualization, modeling, and viscosity studies (United States)

    Atkins, Daniel L.

    Aircraft operation in arctic regions or at high altitudes exposes jet fuel to temperatures below freeze point temperature specifications. Fuel constituents may solidify and remain within tanks or block fuel system components. Military and scientific requirements have been met with costly, low freeze point specialty jet fuels. Commercial airline interest in polar routes and the use of high altitude unmanned aerial vehicles (UAVs) has spurred interest in the effects of low temperatures and low-temperature additives on jet fuel. The solidification of jet fuel due to freezing is not well understood and limited visualization of fuel freezing existed prior to the research presented in this dissertation. Consequently, computational fluid dynamics (CFD) modeling that simulates jet fuel freezing and model validation were incomplete prior to the present work. The ability to simulate jet fuel freezing is a necessary tool for fuel system designers. An additional impediment to the understanding and simulation of jet fuel freezing has been the absence of published low-temperature thermo-physical properties, including viscosity, which the present work addresses. The dissertation is subdivided into three major segments covering visualization, modeling and validation, and viscosity studies. In the first segment samples of jet fuel, JPTS, kerosene, Jet A and Jet A containing additives, were cooled below their freeze point temperatures in a rectangular, optical cell. Images and temperature data recorded during the solidification process provided information on crystal habit, crystallization behavior, and the influence of the buoyancy-driven flow on freezing. N-alkane composition of the samples was determined. The Jet A sample contained the least n-alkane mass. The cooling of JPTS resulted in the least wax formation while the cooling of kerosene yielded the greatest wax formation. The JPTS and kerosene samples exhibited similar crystallization behavior and crystal habits during

  8. XRD and XPS characterisation of transition metal silicide thin films (United States)

    Tam, P. L.; Cao, Y.; Nyborg, L.


    Binary transition metal silicides based on the systems Ti-Si, Fe-Si, Ni-Si and Cr-Si were fabricated on Si wafers by means of ion-beam co-sputter deposition and subsequent annealing. The crystalline structures of the phases formed were identified from the characteristic patterns acquired by means of X-ray diffraction (XRD) measurements. The phase formation sequences were described by means of the Pretorius' effective heat of formation (EHF) model. For the Ti-Si, Fe-Si and Ni-Si systems, single phase thin films of TiSi2, β-FeSi2 and NiSi2 were generated as the model predicts, while a mixture of CrSi + CrSi2 phases was obtained for the Cr-Si system. The surface chemical condition of individual specimens was analysed by using X-ray photoelectron spectroscopy (XPS). The chemical shifts of transition metal 2p3/2 peaks from their metallic to silicide states were depicted by means of the Auger parameters and the Wagner plots. The positive chemical shift of 2.0 eV for Ni 2p3/2 peak of NiSi2 is mainly governed by the initial-state effects. For the other silicide specimens, the initial-state and final-state effects may oppose one another with similar impact. Consequently, smaller binding energy shifts of both negative and positive character are noted; a positive binding energy shift of 0.3 eV for the Fe 2p3/2 level was shown for β-FeSi2 and negative binding energy shifts of 0.1 and 0.3 eV were determined for CrSi + CrSi2 and TiSi2, respectively.

  9. MATPRO: a handbook of materials properties for use in the analysis of light water reactor fuel rod behavior

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, P.E.; Thompson, L.B. (eds.)


    This handbook describes the materials properties correlations and computer subcodes (MATPRO) developed for use with various LWR fuel rod behavior analytical programs at the Idaho National Engineering Laboratory. Documentation and formulations that are generally semiempirical in nature are presented for uranium dioxide and mixed uranium-plutonium dioxide fuel, zircaloy cladding, gas mixture, and LWR fuel rod material properties.

  10. Refueling Behavior of Flexible Fuel Vehicle Drivers in the Federal Fleet

    Energy Technology Data Exchange (ETDEWEB)

    Daley, R.; Nangle, J.; Boeckman, G.; Miller, M.


    Federal fleets are a frequent subject of legislative and executive efforts to lead a national transition to alternative fuels and advanced vehicle technologies. Section 701 of the Energy Policy Act of 2005 requires that all dual-fueled alternative fuel vehicles in the federal fleet be operated on alternative fuel 100% of the time when they have access to it. However, in Fiscal Year (FY) 2012, drivers of federal flex fuel vehicles (FFV) leased through the General Services Administration refueled with E85 24% of the time when it was available--falling well short of the mandate. The U.S. Department of Energy's National Renewable Energy Laboratory completed a 2-year Laboratory Directed Research and Development project to identify the factors that influence the refueling behavior of federal FFV drivers. The project began with two primary hypotheses. First, information scarcity increases the tendency to miss opportunities to purchase E85. Second, even with perfect information, there are limits to how far drivers will go out of their way to purchase E85. This paper discusses the results of the project, which included a June 2012 survey of federal fleet drivers and an empirical analysis of actual refueling behavior from FY 2009 to 2012. This research will aid in the design and implementation of intervention programs aimed at increasing alternative fuel use and reducing petroleum consumption.

  11. Test Plans for Investigating Molten Fuel Behavior in Coolant Channel during SFR Core Melting Accidents

    Energy Technology Data Exchange (ETDEWEB)

    Suk, Soo Dong; Hahn, Doo Hee; Lee, Yong Bum


    The metal-fueled, sodium-cooled fast reactor system is expected to accommodate all credible malfunctions or accident initiators passively without damage to the core. However, the evaluation of the safety performance and the containment requirements for this system will most likely require consideration of postulated low-probability accident sequences that result in partial or whole core melting. For these sequences, some phenomenological uncertainties exist and experimental data are needed for modeling purposes. One such data need is concerned with the potential for freezing and plugging of molten metallic fuel in above-and below-core structures and possibly in inter subassembly spaces. The first basic data need is the properties for metallic fuel/steel mixtures such as liquidus/solidus and mobilization temperatures, as part of measurement of phenomenological data describing the relocation and freezing behavior of molten metallic fuel. Accordingly, plans for two different tests, one for determination of the liquidus/solidus temperature and another for determination of the mobilization temperature, are described in this report. Test plans are then described in the report for the investigations of the relocation and freezing behavior of molten metallic fuel in coolant channels, including possible chemical interactions of molten fuel with the channel steel structure.

  12. Analysis of the Coupling Behavior of PEM Fuel Cells and DC-DC Converters

    Directory of Open Access Journals (Sweden)

    Achim Kienle


    Full Text Available The connection between PEM fuel cells and common DC-DC converters is examined. The analysis is model-based and done for boost, buck and buck-boost converters. In a first step, the effect of the converter ripples upon the PEM fuel cell is shown. They introduce oscillations in the fuel cell. Their appearance is explained, discussed and possibilities for their suppression are given. After that, the overall behaviors of the coupled fuel cell-converter systems are analyzed. It is shown, that neither stationary multiplicities nor oscillations can be introduced by the couplings and therefore separate control approaches for both the PEMFC and the DC-DC converters are applicable.

  13. Fission product behavior during the PBF (Power Burst Facility) Severe Fuel Damage Test 1-1

    Energy Technology Data Exchange (ETDEWEB)

    Hartwell, J K; Petti, D A; Hagrman, D L; Jensen, S M; Cronenberg, A W


    In response to the accident at Three Mile Island Unit 2 (TMI-2), the United States Nuclear Regulatory Commission (USNRC) initiated a series of Severe Fuel Damage tests that were performed in the Power Burst Facility at the Idaho National Engineering Laboratory to obtain data necessary to understand (a) fission product release, transport, and deposition; (b) hydrogen generation; and (c) fuel/cladding material behavior during degraded core accidents. Data are presented about fission product behavior noted during the second experiment of this series, the Severe Fuel Damage Test 1-1, with an in-depth analysis of the fission product release, transport, and deposition phenomena that were observed. Real-time release and transport data of certain fission products were obtained from on-line gamma spectroscopy measurements. Liquid and gas effluent grab samples were collected at selected periods during the test transient. Additional information was obtained from steamline deposition analysis. From these and other data, fission product release rates and total release fractions are estimated and compared with predicted release behavior using current models. Fission product distributions and a mass balance are also summarized, and certain probable chemical forms are predicted for iodine, cesium, and tellurium. An in-depth evaluation of phenomena affecting the behavior of the high-volatility fission products - xenon, krypton, iodine, cesium, and tellurium - is presented. Analysis indicates that volatile release from fuel is strongly influenced by parameters other than fuel temperature. Fission product behavior during transport through the Power Burst Facility effluent line to the fission product monitoring system is assessed. Tellurium release behavior is also examined relatve to the extent of Zircaloy cladding oxidation. 81 fig., 53 tabs.

  14. Growth and stability of dysprosium silicide nanostructures on Si(001) (United States)

    Zeman, Matthew; Nemanich, Robert


    The growth and coarsening dynamics of epitaxial dysprosium silicide nanostructures on Si(001) are observed using tunable ultra-violet free electron laser excitation for photo-electron emission microscopy (PEEM). A dense array of compact silicide nanostructures is observed to coarsen during annealing at 950-1050C. Some of the nanostructures grow into large flat-topped rectangular islands at the expense of smaller islands which disappear via Ostwald ripening. The coarsening rate of the island distribution increases with increasing temperature, and the formation of a flat top on the growing islands is related to strain relaxation. Additionally, the shape and growth rates of the islands may be influenced by the island crystal structure and/or local island distributions. A subsequent deposition of dysprosium onto the surface results in the nucleation of new island and nanowire structures. Immediately after the deposition is terminated the nanowires begin to decay from the ends while the larger island structures grow. The decay of the wires can be attributed to Ostwald ripening and is explained in terms of the Gibbs-Thompson relation, where the high adatom concentration at the nanowire ends leads to the diffusion of adatoms away from the wires towards the larger surrounding structures. In situ movies will be presented which detail the growth and coarsening processes.

  15. Fuel loads and simulated fire behavior in "old-stage" beetle-infested ponderosa pine of the Colorado Plateau (United States)

    E. Matthew Hansen; Morris C. Johnson; Barbara J. Bentz; James C. Vandygriff; A. Steven. Munson


    Recent bark beetle outbreaks in western North America have led to concerns regarding changes in fuel profiles and associated changes in fire behavior. Data are lacking for a range of infestation severities and time since outbreak, especially for relatively arid cover types. We surveyed fuel loads and simulated fire behavior for ponderosa pine stands of the...

  16. Practical tools for assessing potential crown fire behavior and canopy fuel characteristics (United States)

    Martin E. Alexander; Miguel G. Cruz


    This presentation recapitulates the main points made at a technology and information transfer workshop held in advance of the conference that provided overviews of two software applications, developed by the authors, for use in assessing crown fire behavior and canopy fuel characteristics. These are the Crown Fire Initiation and Spread (CFIS) software system and the...

  17. Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Robert; Tomé, Carlos; Liu, Wenfeng; Alankar, Alankar; Subramanian, Gopinath; Stanek, Christopher


    Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. CASL has endeavored to improve upon this approach by incorporating a microstructurally-based, atomistically-informed, zirconium alloy mechanical deformation analysis capability into the BISON-CASL engineering scale fuel performance code. Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tome´ [2], has been coupled with BISON-CASL to represent the mechanistic material processes controlling the deformation behavior of the cladding. A critical component of VPSC is the representation of the crystallographic orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON-CASL and provides initial results utilizing the coupled functionality.

  18. Linking 3D spatial models of fuels and fire: Effects of spatial heterogeneity on fire behavior (United States)

    Russell A. Parsons; William E. Mell; Peter McCauley


    Crownfire endangers fire fighters and can have severe ecological consequences. Prediction of fire behavior in tree crowns is essential to informed decisions in fire management. Current methods used in fire management do not address variability in crown fuels. New mechanistic physics-based fire models address convective heat transfer with computational fluid dynamics (...

  19. Contact behavior modelling and its size effect on proton exchange membrane fuel cell (United States)

    Qiu, Diankai; Peng, Linfa; Yi, Peiyun; Lai, Xinmin; Janßen, Holger; Lehnert, Werner


    Contact behavior between the gas diffusion layer (GDL) and bipolar plate (BPP) is of significant importance for proton exchange membrane fuel cells. Most current studies on contact behavior utilize experiments and finite element modelling and focus on fuel cells with graphite BPPs, which lead to high costs and huge computational requirements. The objective of this work is to build a more effective analytical method for contact behavior in fuel cells and investigate the size effect resulting from configuration alteration of channel and rib (channel/rib). Firstly, a mathematical description of channel/rib geometry is outlined in accordance with the fabrication of metallic BPP. Based on the interface deformation characteristic and Winkler surface model, contact pressure between BPP and GDL is then calculated to predict contact resistance and GDL porosity as evaluative parameters of contact behavior. Then, experiments on BPP fabrication and contact resistance measurement are conducted to validate the model. The measured results demonstrate an obvious dependence on channel/rib size. Feasibility of the model used in graphite fuel cells is also discussed. Finally, size factor is proposed for evaluating the rule of size effect. Significant increase occurs in contact resistance and porosity for higher size factor, in which channel/rib width decrease.

  20. Fuels and predicted fire behavior in the southern Appalachian Mountains and fire and fire surrogate treatments (United States)

    Thomas Waldrop; Ross J. Phillips; Dean A. Simon


    This study tested the success of fuel reduction treatments for mitigating wildfire behavior in an area that has had little previous research on fire, the southern Appalachian Mountains. A secondary objective of treatments was to restore the community to an open woodland condition. Three blocks of four treatments were installed in a mature hardwood forest in western...

  1. Influence of IR-laser irradiation on {alpha}-SiC-chromium silicides ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Vlasova, M. [Centro de Investigaciones en Ingenieria y Ciencias Aplicadas, Autonomous University of State of Morelos, Av. Universidad 1001-Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico)]. E-mail:; Marquez Aguilar, P.A. [Centro de Investigaciones en Ingenieria y Ciencias Aplicadas, Autonomous University of State of Morelos, Av. Universidad 1001-Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico); Resendiz-Gonzalez, M.C. [Centro de Investigaciones en Ingenieria y Ciencias Aplicadas, Autonomous University of State of Morelos, Av. Universidad 1001-Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico); Kakazey, M. [Centro de Investigaciones en Ingenieria y Ciencias Aplicadas, Autonomous University of State of Morelos, Av. Universidad 1001-Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico); Bykov, A. [Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Str. Krzhizhanovskogo 3, Kiev 252680 (Ukraine); Gonzalez Morales, I. [Centro de Investigaciones en Ingenieria y Ciencias Aplicadas, Autonomous University of State of Morelos, Av. Universidad 1001-Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico)


    This project investigated the influence of IR-laser irradiation ({lambda} = 1064 nm, P = 240 mW) on composite ceramics SiC-chromium silicides (CrSi{sub 2}, CrSi, Cr{sub 5}Si{sub 3}) by methods of X-ray diffraction, electron microscopy, atomic force microscopy, and X-ray microanalysis. Samples were irradiated in air. It was established that a surface temperature of 1990 K was required to melt chromium silicides, evaporate silicon from SiC, oxidize chromium silicides, and enrich superficial layer by carbon and chromium oxide.

  2. Irradiation behavior of modified high-performance nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Jungwirth, Rainer


    To overcome the problem of UMo/Al fuel swelling, four different possibilities have been identified: (i) the modification of the Al matrix by adding diffusion limiting elements (ii) the insertion of a diffusion barrier at the interface UMo-Al (iii) further alloying the UMo with a third element to stabilize the γ-UMo phase (iv) a combination of means (i)-(iii). In consequence, 20 different UMoX/AlY (X=Si, Ti, Mg, Bi, with and without oxidation layer; Y=Nb, Ti, Pt) samples have been examined before and after irradiation with Iodine at 80MeV. First it has been shown, that a protective oxidation layer on the UMo grains does not prevent the formation of a interdiffusion layer. In contrast, additions to the Al matrix can be reduced to the self-acting formation of a protective layer at the UMo/Al interface. Additions to the UMo to stabilize the γ-UMo upon heating are of minor importance since irradiation reverses the phase decomposition of UMo.

  3. Behavior of a methanol fuel cell in transitory regime

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.F.; Pilla, A.S.; Duarte, M.M.E.; Mayer, C.E. [Instituto de Ingenieria Electroquimica y Corrosion, Depto. de Ingenieria Quimica, Universidad Nacional del Sur, Av. Alem 1253, 8000 Bahia Blanca (Argentina)


    The operation of a polymeric electrolyte methanol/air fuel cell connected to a storage tank with anolyte batch recycle is analyzed. When the cell is discharged at constant current, far below the anode reaction limiting current density, the concentration in the tank is found to decrease with time following a lineal variation. At zero time, a high CO{sub 2} concentration is detected in the air leaving the cathode compartment, which increased when higher methanol concentration is used in the anode compartment. This effect is associated to the crossover of methanol through the membrane. The amount of CO{sub 2} in the air outlet is important, and both this quantity and the crossover flux decrease when methanol concentration diminish in the anolyte. A model derived from electrochemical reactor analysis, that correlates methanol concentration changes in the storage tank, and methanol concentration at the anodic compartment exit with the amount consumed in the cell reaction and the flow through the membrane is developed. (author)

  4. Comparison of nickel silicide and aluminium ohmic contact metallizations for low-temperature quantum transport measurements

    Directory of Open Access Journals (Sweden)

    Polley Craig


    Full Text Available Abstract We examine nickel silicide as a viable ohmic contact metallization for low-temperature, low-magnetic-field transport measurements of atomic-scale devices in silicon. In particular, we compare a nickel silicide metallization with aluminium, a common ohmic contact for silicon devices. Nickel silicide can be formed at the low temperatures (<400°C required for maintaining atomic precision placement in donor-based devices, and it avoids the complications found with aluminium contacts which become superconducting at cryogenic measurement temperatures. Importantly, we show that the use of nickel silicide as an ohmic contact at low temperatures does not affect the thermal equilibration of carriers nor contribute to hysteresis in a magnetic field.

  5. NMOS contact resistance reduction with selenium implant into NiPt silicide (United States)

    Rao, K. V.; Khaja, F. A.; Ni, C. N.; Muthukrishnan, S.; Darlark, A.; Lei, J.; Peidous, I.; Brand, A.; Henry, T.; Variam, N.; Erokhin, Y.


    A 25% reduction in NMOS contact resistance (Rc) was achieved by Selenium implantation into NiPt silicide film in VIISta Trident high-current single-wafer implanter. The Trident implanter is designed for shallow high-dose implants with high beam currents to maintain high throughput (for low CoO), with improved micro-uniformity and no energy contamination. The integration of Se implant was realized using a test chip dedicated to investigating silicide/junction related electrical properties and testable after silicidation. The silicide module processes were optimized, including the pre-clean (prior to RF PVD NiPt dep) and pre- and post-implant anneals. A 270°C soak anneal was used for RTP1, whereas a msec laser anneal was employed for RTP2 with sufficient process window (800-850°C), while maintaining excellent junction characteristics without Rs degradation.

  6. Silicon to Nickel Silicide Longitudinal Nanowire Heterostructures: Synthesis, Electrical Characterization and Novel Devices


    Weber, Walter Michael


    The scope of this thesis is the synthesis and electrical characterization of Si to Ni silicide nanowire heterostructures with the focus on investigating their electronic transport properties and conceiving a novel type of transistor. Intrinsic Si nanowires (SiNW) were grown employing the vapor-liquid-solid mechanism. A central part of this thesis is the development of the longitudinal intrusion of Ni silicide into the SiNWs resulting in interfaces with a sharpness of at most a couple of n...

  7. Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Robert, E-mail: [Pacific Northwest National Laboratory (United States); Tomé, Carlos, E-mail: [Los Alamos National Laboratory (United States); Liu, Wenfeng, E-mail: [ANATECH Corporation (United States); Alankar, Alankar, E-mail: [Indian Institute of Technology Bombay (India); Subramanian, Gopinath, E-mail: [University of Southern Mississippi (United States); Stanek, Christopher, E-mail: [Los Alamos National Laboratory (United States)


    Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical constitutive models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. To improve upon this approach, a microstructurally-based zirconium alloy mechanical deformation analysis capability is being developed within the United States Department of Energy Consortium for Advanced Simulation of Light Water Reactors (CASL). Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tomé [1], has been coupled with the BISON engineering scale fuel performance code to represent the mechanistic material processes controlling the deformation behavior of light water reactor (LWR) cladding. A critical component of VPSC is the representation of the crystallographic nature (defect and dislocation movement) and orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. A future goal is for VPSC to obtain information on reaction rate kinetics from atomistic calculations to inform the defect and dislocation behavior models described in VPSC. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON and provides initial results utilizing the coupled functionality.

  8. Lethal and behavioral impacts of diesel and fuel oil on the Antarctic amphipod Paramoera walkeri. (United States)

    Brown, Kathryn E; King, Catherine K; Harrison, Peter L


    Toxicity testing with Antarctic species is required for risk assessment of fuel spills in Antarctic coastal waters. The lethal and sublethal (movement behavior) sensitivities of adults and juveniles of the Antarctic amphipod Paramoera walkeri to the water accommodated fractions (WAFs) of 3 fuels were estimated in extended-duration tests at -1 °C to 21 d. Response of P. walkeri for lethal hydrocarbon concentrations was slow, with 50% lethal concentrations (LC50s) first able to be estimated at 7 d for adults exposed to Special Antarctic Blend diesel (SAB), which had the highest hydrocarbon concentrations of the 3 fuel WAFs. Juveniles showed greater response to marine gas oil (MGO) and intermediate residual fuel oil (IFO 180) at longer exposure durations and were most sensitive at 21 d to IFO 180 (LC50 = 12 μg/L). Adults were initially more sensitive than juveniles; at 21 d, however, juveniles were more than twice as sensitive as adults to SAB (LC50 = 153 μg/L and 377 μg/L, respectively). Significant effects on movement behavior were evident at earlier time points and lower concentrations than was mortality in all 3 fuel WAFs, and juveniles were highly sensitive to sublethal effects of MGO. These first estimates of Antarctic amphipod sensitivity to diesel and fuel oils in seawater contribute to the development of ecologically relevant risk assessments for management of hydrocarbon contamination in the region. Environ Toxicol Chem 2017;36:2444-2455. © 2017 SETAC. © 2017 SETAC.

  9. Mechanical Behavior of Free-Standing Fuel Cell Electrodes on Water Surface. (United States)

    Kim, Sanwi; Kim, Jae-Han; Oh, Jong-Gil; Jang, Kyung-Lim; Jeong, Byeong-Heon; Hong, Bo Ki; Kim, Taek-Soo


    Fundamental understanding of the mechanical behavior of polymer electrolyte fuel cell electrodes as free-standing materials is essential to develop mechanically robust fuel cells. However, this has been a significant challenge due to critical difficulties, such as separating the pristine electrode from the substrate without damage and precisely measuring the mechanical properties of the very fragile and thin electrodes. We report the mechanical behavior of free-standing fuel cell electrodes on the water surface through adopting an innovative ice-assisted separation method to separate the electrode from decal transfer film. It is found that doubling the ionomer content in electrodes increases not only the tensile stress at the break and the Young's modulus (E) of the electrodes by approximately 2.1-3.5 and 1.7-2.4 times, respectively, but also the elongation at the break by approximately 1.5-1.7 times, which indicates that stronger, stiffer, and tougher electrodes are attained with increasing ionomer content, which have been of significant interest in materials research fields. The scaling law relationship between Young's modulus and density (ρ) has been unveiled as E ∼ ρ(1.6), and it is compared with other materials. These findings can be used to develop mechanically robust electrodes for fuel cell applications.


    Energy Technology Data Exchange (ETDEWEB)

    Samuel J. Miller; Hakan Ozaltun


    This article analyzes dimensional changes due to irradiation of monolithic plate-type nuclear fuel and compares results with finite element analysis of the plates during fabrication and irradiation. Monolithic fuel plates tested in the Advanced Test Reactor (ATR) at Idaho National Lab (INL) are being used to benchmark proposed fuel performance for several high power research reactors. Post-irradiation metallographic images of plates sectioned at the midpoint were analyzed to determine dimensional changes of the fuel and the cladding response. A constitutive model of the fabrication process and irradiation behavior of the tested plates was developed using the general purpose commercial finite element analysis package, Abaqus. Using calculated burn-up profiles of irradiated plates to model the power distribution and including irradiation behaviors such as swelling and irradiation enhanced creep, model simulations allow analysis of plate parameters that are either impossible or infeasible in an experimental setting. The development and progression of fabrication induced stress concentrations at the plate edges was of primary interest, as these locations have a unique stress profile during irradiation. Additionally, comparison between 2D and 3D models was performed to optimize analysis methodology. In particular, the ability of 2D and 3D models account for out of plane stresses which result in 3-dimensional creep behavior that is a product of these components. Results show that assumptions made in 2D models for the out-of-plane stresses and strains cannot capture the 3-dimensional physics accurately and thus 2D approximations are not computationally accurate. Stress-strain fields are dependent on plate geometry and irradiation conditions, thus, if stress based criteria is used to predict plate behavior (as opposed to material impurities, fine micro-structural defects, or sharp power gradients), unique 3D finite element formulation for each plate is required.

  11. Impacts of climate on shrubland fuels and fire behavior in the Owyhee Basin, Idaho (United States)

    Vogelmann, J. E.; Shi, H.; Hawbaker, T.; Li, Z.


    There is evidence that wildland fire is increasing as a function of global change. However, fire activity is spatially, temporally and ecologically variable across the globe, and our understanding of fire risk and behavior in many ecosystems is limited. After a series of severe fire seasons that occurred during the late 1990's in the western United States, the LANDFIRE program was developed with the goals of providing the fire community with objective spatial fuel data for assessing wildland fire risk. Even with access to the data provided by LANDFIRE, assessing fire behavior in shrublands in sagebrush-dominated ecosystems of the western United States has proven especially problematic, in part due to the complex nature of the vegetation, the variable influence of understory vegetation including invasive species (e.g. cheatgrass), and prior fire history events. Climate is undoubtedly playing a major role, affecting the intra- and inter-annual variability in vegetation conditions, which in turn impacts fire behavior. In order to further our understanding of climate-vegetation-fire interactions in shrublands, we initiated a study in the Owyhee Basin, which is located in southwestern Idaho and adjacent Nevada. Our goals include: (1) assessing the relationship between climate and vegetation condition, (2) quantifying the range of temporal variability in grassland and shrubland fuel loads, (3) identifying methods to operationally map the variability in fuel loads, and (4) assessing how the variability in fuel loads affect fire spread simulations. To address these goals, we are using a wide variety of geospatial data, including remotely sensed time-series data sets derived from MODIS and Landsat, and climate data from DAYMET and PRISM. Remotely-sensed information is used to characterize climate-induced temporal variability in primary productivity in the Basin, where fire spread can be extensive after senescence when dry vegetation is added to dead fuel loads. Gridded

  12. Sudden oak death-caused changes to surface fuel loading and potential fire behavior in Douglas-fir-tanoak forests (United States)

    Y.S. Valachovic; C.A. Lee; H. Scanlon; J.M. Varner; R. Glebocki; B.D. Graham; D.M. Rizzo


    We compared stand structure and fuel loading in northwestern California forests invaded by Phytophthora ramorum, the cause of sudden oak death, to assess whether the continued presence of this pathogen alters surface fuel loading and potential fire behavior in ways that may encumber future firefighting response. To attempt to account for these...

  13. Technology CAD of silicided Schottky barrier MOSFET for elevated source-drain engineering

    Energy Technology Data Exchange (ETDEWEB)

    Saha, A.R. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)]. E-mail:; Chattopadhyay, S. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India); School of Electrical, Electronics and Computer Engineering, University of Newcastle, Newcastle upon Tyne (United Kingdom); Bose, C. [Department of Electronics and Telecommunication Engineering, Jadavpur University, Calcutta 700032 (India); Maiti, C.K. [Department of Electronics and ECE, IIT, Kharagpur 721302 (India)


    Technology CAD has been used to study the performance of a silicided Schottky barrier (SB) MOSFET with gate, source and drain contacts realized with nickel-silicide. Elevated source-drain structures have been used towards the S/D engineering of CMOS devices. A full process-to-device simulation has been employed to predict the performance of sub-micron SB n-MOSFETs for the first time. A model for the diffusion and alloy growth kinetics has been incorporated in SILVACO-ATLAS and ATHENA to explore the processing and design parameter space for the Ni-silicided MOSFETs. The temperature and concentration dependent diffusion model for NiSi have been developed and necessary material parameters for nickel-silicide and epitaxial-Si have been incorporated through the C-interpreter function. Two-dimensional (2D) process-to-device simulations have also been used to study the dc and ac (RF) performance of silicided Schottky barrier (SB) n-MOSFETs. The extracted sheet resistivity, as a function of annealing temperature of the silicided S/D contacts, is found to be lower than the conventional contacts currently in use. It is also shown that the Technology CAD has the full capability to predict the possible dc and ac performance enhancement of a MOSFET with elevated S/D structures. While the simulated dc performance shows a clear enhancement, the RF analyses show no performance degradation in the cut-off frequency/propagation delay and also improve the ac performance due to the incorporation of silicide contacts in the S/D region.

  14. The dynamic and steady state behavior of a PEM fuel cell as an electric energy source

    Energy Technology Data Exchange (ETDEWEB)

    Costa, R.A. [Fundacao Educacional de Barretos (FEB), School of Electrical Engineering, Av. Prof. Roberto Frade Monte, 389 Aeroporto, 14783.226, Barretos, SP (Brazil); Camacho, J.R. [Universidade Federal de Uberlandia, School of Electrical Engineering, Rural Electricity and Alternative Energy Sources Lab., Av. Joao N. de Avila, 2121, 38400.902, Uberlandia, MG (Brazil)


    The main objective of this work is to extract information on the internal behavior of three small polymer electrolyte membrane fuel cells under static and dynamic load conditions. A computational model was developed using Scilab [SCILAB 4, Scilab-a free scientific software package,, INRIA, France, December, 2005] to simulate the static and dynamic performance [J.M. Correa, A.F. Farret, L.N. Canha, An analysis of the dynamic performance of proton exchange membrane fuel cells using an electrochemical model, in: 27th Annual Conference of IEEE Industrial Electronics Society, 2001, pp. 141-146] of this particular type of fuel cell. This dynamic model is based on electrochemical equations and takes into consideration most of the chemical and physical characteristics of the device in order to generate electric power. The model takes into consideration the operating, design parameters and physical material properties. The results show the internal losses and concentration effects behavior, which are of interest for power engineers and researchers. (author)

  15. Pyrolysis behavior of tire-derived fuels at different temperatures and heating rates. (United States)

    Unapumnuk, Kessinee; Keener, Tim C; Lu, Mingming; Khang, Soon-Jai


    Pyrolytic product distribution rates and pyrolysis behavior of tire-derived fuels (TDF) were investigated using thermogravimetric analyzer (TGA) techniques. A TGA was designed and built to investigate the behavior and products of pyrolysis of typical TDF specimens. The fundamental knowledge of TGA analysis and principal fuel analysis are applied in this study. Thermogravimetry of the degradation temperature of the TDF confirms the overall decomposition rate of the volatile products during the depolymerization reaction. The principal fuel analysis (proximate and ultimate analysis) of the pyrolytic char products show the correlation of volatilization into the gas and liquid phases and the existence of fixed carbon and other compounds that remain as a solid char. The kinetic parameters were calculated using least square with minimizing sum of error square technique. The results show that the average kinetic parameters of TDF are the activation energy, E = 1322 +/- 244 kJ/mol, a pre-exponential constant of A = 2.06 +/- 3.47 x 10(10) min(-1), and a reaction order n = 1.62 +/- 0.31. The model-predicted rate equations agree with the experimental data. The overall TDF weight conversion represents the carbon weight conversion in the sample.

  16. Epitaxial insertion of gold silicide nanodisks during the growth of silicon nanowires. (United States)

    Um, Han-Don; Jee, Sang-Won; Park, Kwang-Tae; Jung, Jin-Young; Guo, Zhongyi; Lee, Jung-Ho


    Nanodisk-shaped, single-crystal gold silicide heterojunctions were inserted into silicon nanowires during vapor-liquid-solid growth using Au as a catalyst within a specific range of chlorine-to-hydrogen atomic ratio. The mechanism of nanodisk formation has been investigated by changing the source gas ratio of SiCl4 to H2. We report that an over-supply of silicon into the Au-Si liquid alloy leads to highly supersaturated solution and enhances the precipitation of Au in the silicon nanowires due to the formation of unstable phases within the liquid alloy. It is shown that the gold precipitates embedded in the silicon nanowires consisted of a metastable gold silicide. Interestingly, faceting of gold silicide was observed at the Au/Si interfaces, and silicon nanowires were epitaxially grown on the top of the nanodisk by vapor-liquid-solid growth. High resolution transmission electron microscopy confirmed that gold silicide nanodisks are epitaxially connected to the silicon nanowires in the direction of growth direction. These gold silicide nanodisks would be useful as nanosized electrical junctions for future applications in nanowire interconnections.

  17. Effect of silicide/silicon hetero-junction structure on thermal conductivity and Seebeck coefficient. (United States)

    Choi, Wonchul; Park, Young-Sam; Hyun, Younghoon; Zyung, Taehyoung; Kim, Jaehyeon; Kim, Soojung; Jeon, Hyojin; Shin, Mincheol; Jang, Moongyu


    We fabricated a thermoelectric device with a silicide/silicon laminated hetero-structure by using RF sputtering and rapid thermal annealing. The device was observed to have Ohmic characteristics by I-V measurement. The temperature differences and Seebeck coefficients of the proposed silicide/silicon laminated and bulk structure were measured. The laminated thermoelectric device shows suppression of heat flow from the hot to cold side. This is supported by the theory that the atomic mass difference between silicide and silicon creates a scattering center for phonons. The major impact of our work is that phonon transmission is suppressed at the interface between silicide and silicon without degrading electrical conductivity. The estimated thermal conductivity of the 3-layer laminated device is 126.2 +/- 3.7 W/m. K. Thus, by using the 3-layer laminated structure, thermal conductivity is reduced by around 16% compared to bulk silicon. However, the Seebeck coefficient of the thermoelectric device is degraded compared to that of bulk silicon. It is understood that electrical conductivity is improved by using silicide as a scattering center.

  18. Modeling and simulation of the dynamic behavior of portable proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, C.


    In order to analyze the operational behavior, a mathematical model of planar self-breathing fuel cells is developed and validated in Chapter 3 of this thesis. The multicomponent transport of the species is considered as well as the couplings between the transport processes of heat, charge, and mass and the electrochemical reactions. Furthermore, to explain the oxygen mass transport limitation in the porous electrode of the cathode side an agglomerate model for the oxygen reduction reaction is developed. In Chapter 4 the important issue of liquid water generation and transport in PEMFCs is addressed. One of the major tasks when operating this type of fuel cell is avoiding the complete flooding of the PEMFC during operation. A one-dimensional and isothermal model is developed that is based on a coupled system of partial differential equations. The model contains a dynamic and two-phase description of the proton exchange membrane fuel cell. The mass transport in the gas phase and in the liquid phase is considered as well as the phase transition between liquid water and water vapor. The transport of charges and the electrochemical reactions are part of the model. Flooding effects that are caused by liquid water accumulation are described by this model. Moreover, the model contains a time-dependent description of the membrane that accounts for Schroeder's paradox. The model is applied to simulate cyclic voltammograms. Chapter 5 is focused on the dynamic investigation of PEMFC stacks. Understanding the dynamic behavior of fuel cell stacks is important for the operation and control of fuel cell stacks. Using the single cell model of Chapter 3 and the dynamic model of Chapter 4 as basis, a mathematical model of a PEMFC stack is developed. However, due to the complexity of a fuel cell stack, the spatial resolution and dynamic description of the liquid water transport are not accounted for. These restrictions allow for direct comparison between the solution variables of

  19. Study of agglomeration behavior of combustion-synthesized nano-crystalline ceria using new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Srirupa T.; Bedekar, Vinila [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Patra, A.; Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)], E-mail:


    Ceria powders were prepared by gel combustion process using cerium nitrate and hitherto unexplored amino acid fuels such as aspartic acid, glutamic acid, arginine, tryptophan, phenyl alanine, valine, etc. These powders were characterized by X-ray diffraction, surface area analysis, sinterability, dynamic light scattering, scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS). The combustion-synthesized powders were agglomerates of nano-crystallites. SAXS profiles of the powders prepared using tryptophan, phenyl alanine and dimethyl urea exhibited fractal behavior.

  20. Anisotropic thermal expansion of Ni, Pd and Pt germanides and silicides (United States)

    Geenen, F. A.; Knaepen, W.; Moens, F.; Brondeel, L.; Leenaers, A.; Van den Berghe, S.; Detavernier, C.


    Silicon or germanium-based transistors are nowadays used in direct contact with silicide or germanide crystalline alloys for semiconductor device applications. Since these compounds are formed at elevated temperatures, accurate knowledge of the thermal expansion of both substrate and the contact is important to address temperature depending effects such as thermal stress. Here we report the linear coefficients of thermal expansion of Ni-, Pd- and Pt-based mono-germanides, mono-silicides and di-metal-silicides as determined by powder-based x-ray diffraction between 300 and 1225 K. The investigated mono-metallic compounds, all sharing the MnP crystal structure, as well as Pd2Si and Pt2Si exhibit anisotropic expansion. By consequence, this anisotropic behaviour should be taken into account for evaluating the crystal unit’s cell at elevated temperatures.

  1. Accident-tolerant oxide fuel and cladding (United States)

    Mariani, Robert D.


    Systems and methods for accident tolerant oxide fuel. One or more disks can be placed between fuel pellets comprising UO.sub.2, wherein such disks possess a higher thermal conductivity material than that of the UO.sub.2 to provide enhanced heat rejection thereof. Additionally, a cladding coating comprising zircaloy coated with a material that provides stability and high melting capability can be provided. The pellets can be configured as annular pellets having an annulus filled with the higher thermal conductivity material. The material coating the zircaloy can be, for example, Zr.sub.5Si.sub.4 or another silicide such as, for example, a Zr-Silicide that limits corrosion. The aforementioned higher thermal conductivity material can be, for example, Si, Zr.sub.xSi.sub.y, Zr, or Al.sub.2O.sub.3.

  2. Crystal Structure of Silicides in a Ti - 0.7 WT.% Si Nanostructured Alloy (United States)

    Ivanov, M. B.; Manokhin, S. S.; Kolobova, A. Yu.


    Using warm, lengthwise grooved-roll processing of the Ti - 0.7 wt.% Si alloy, a nanostructured state is formed in it at 873 K with the grain-subgrain elements measuring about 280 nm. The titanium silicides precipitating during the dynamic strain-induced aging of the alloy are investigated by the methods of high-resolution scanning electron microscopy. It is found that the shape of the silicides is close to spherical, they have an FCClattice and an incoherent interface with the matrix.

  3. Optical anisotropy of quasi-1D rare-earth silicide nanostructures on Si(001) (United States)

    Chandola, S.; Speiser, E.; Esser, N.; Appelfeller, S.; Franz, M.; Dähne, M.


    Rare earth metals are known to interact strongly with Si(001) surfaces to form different types of silicide nanostructures. Using STM to structurally characterize Dy and Tb silicide nanostructures on vicinal Si(001), it will be shown that reflectance anisotropy spectroscopy (RAS) can be used as an optical fingerprint technique to clearly distinguish between the formation of a semiconducting two-dimensional wetting layer and the metallic one-dimensional nanowires. Moreover, the distinctive spectral features can be related to structural units of the nanostructures. RAS spectra of Tb and Dy nanostructures are found to show similar features.

  4. Optically probing the detection mechanism in a molybdenum silicide superconducting nanowire single-photon detector

    CERN Document Server

    Caloz, Misael; Timoney, Nuala; Weiss, Markus; Gariglio, Stefano; Warburton, Richard J; Schönenberger, Christian; Renema, Jelmer; Zbinden, Hugo; Bussieres, Felix


    We experimentally investigate the detection mechanism in a meandered molybdenum silicide (MoSi) superconducting nanowire single-photon detector by characterising the detection probability as a function of bias current in the wavelength range of 750 to 2050 nm. Contrary to some previous observations on niobium nitride (NbN) or tungsten silicide (WSi) detectors, we find that the energy-current relation is nonlinear in this range. Furthermore, thanks to the presence of a saturated detection efficiency over the whole range of wavelengths, we precisely quantify the shape of the curves. This allows a detailed study of their features, which are indicative of both Fano fluctuations and position-dependent effects.

  5. Carbon mediated reduction of silicon dioxide and growth of copper silicide particles in uniform width channels

    DEFF Research Database (Denmark)

    Pizzocchero, Filippo; Bøggild, Peter; Booth, Tim


    We show that surface arc-discharge deposited carbon plays a critical intermediary role in the breakdown of thermally grown oxide diffusion barriers of 90 nm on a silicon wafer at 1035°C in an Ar/H2 atmosphere, resulting in the formation of epitaxial copper silicide particles in ≈ 10 μm wide...... channels, which are aligned with the intersections of the (100) surface of the wafer and the {110} planes on an oxidized silicon wafer, as well as endotaxial copper silicide nanoparticles within the wafer bulk. We apply energy dispersive x-ray spectroscopy, in combination with scanning and transmission...

  6. Partitioning behavior of aromatic components in jet fuel into diverse membrane-coated fibers. (United States)

    Baynes, Ronald E; Xia, Xin-Rui; Barlow, Beth M; Riviere, Jim E


    Jet fuel components are known to partition into skin and produce occupational irritant contact dermatitis (OICD) and potentially adverse systemic effects. The purpose of this study was to determine how jet fuel components partition (1) from solvent mixtures into diverse membrane-coated fibers (MCFs) and (2) from biological media into MCFs to predict tissue distribution. Three diverse MCFs, polydimethylsiloxane (PDMS, lipophilic), polyacrylate (PA, polarizable), and carbowax (CAR, polar), were selected to simulate the physicochemical properties of skin in vivo. Following an appropriate equilibrium time between the MCF and dosing solutions, the MCF was injected directly into a gas chromatograph/mass spectrometer (GC-MS) to quantify the amount that partitioned into the membrane. Three vehicles (water, 50% ethanol-water, and albumin-containing media solution) were studied for selected jet fuel components. The more hydrophobic the component, the greater was the partitioning into the membranes across all MCF types, especially from water. The presence of ethanol as a surrogate solvent resulted in significantly reduced partitioning into the MCFs with discernible differences across the three fibers based on their chemistries. The presence of a plasma substitute (media) also reduced partitioning into the MCF, with the CAR MCF system being better correlated to the predicted partitioning of aromatic components into skin. This study demonstrated that a single or multiple set of MCF fibers may be used as a surrogate for octanol/water systems and skin to assess partitioning behavior of nine aromatic components frequently formulated with jet fuels. These diverse inert fibers were able to assess solute partitioning from a blood substitute such as media into a membrane possessing physicochemical properties similar to human skin. This information may be incorporated into physiologically based pharmacokinetic (PBPK) models to provide a more accurate assessment of tissue dosimetry of

  7. Growth, structure and lattice dynamics of rare earth silicide nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Anja


    In the present thesis the epitaxial growth, crystal structure, stoichiometry, thermal stability and lattice dynamics of self-organized EuSi{sub 2} and DySi{sub 2} films, nanoislands and nanowires are investigated. The rare earth silicide (RESi) nanostructures have attracted considerable interest due to their high conductivity, very low Schottky barrier heights, remarkable chemical stability, self-organization in high area density and defects-free nano-objects with tunable size and shape, and the direct integration into the Si technology. The extensive research is driven by the continuous downscaling of the CMOS electronics that require new approaches in the devices architecture and circuits interconnects. Although RESi nanostructures attracted a lot of interest already several years ago and a lot of research has been done in this field, the lattice dynamics of these materials are still unknown. Recent developments at third generation synchrotron radiation sources have brought their performance to a stage where phonon spectroscopy of nanostructures and thin layers became feasible using nuclear inelastic X-ray scattering. This novel experimental technique is based on the process of phonon-assisted nuclear resonant absorption/emission of X-rays from the nuclei of Moessbauer-active isotopes. The method provides direct access to the phonon density of states (DOS) of the investigated element. Together with the ab initio calculations it was possible to get a comprehensive understanding of the lattice dynamics. EuSi{sub 2} films and nanoislands and DySi{sub 2} films, nanoislands and nanowires have been grown on the vicinal Si(001) surface by molecular beam epitaxy. While DySi{sub 2} was grown following known growth procedures, the growth conditions for EuSi{sub 2} had to be established first. EuSi{sub 2} was grown at two different growth conditions to study the influence of crystal structure and morphology upon different growth temperatures. The structure has been

  8. Effect of process parameters on the dynamic behavior of polymer electrolyte membrane fuel cells for electric vehicle applications

    Directory of Open Access Journals (Sweden)

    A.A. Abd El Monem


    Full Text Available This paper presents a dynamic mathematical model for Polymer Electrolyte Membrane “PEM” fuel cell systems to be used for electric vehicle applications. The performance of the fuel cell, depending on the developed model and taking the double layer charging effect into account, is investigated with different process parameters to evaluate their effect on the unit behavior. Thus, it will be easy to develop suitable controllers to regulate the unit operation, which encourages the use of fuel cells especially with electric vehicles applications. The steady-state performance of the fuel cell is verified using a comparison with datasheet data and curves provided by the manufacturer. The results and conclusions introduced in this paper provide a base for further investigation of fuel cells-driven dc motors for electric vehicle.

  9. Water splitting and electricity with semiconducting silicides in sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Demuth, Martin [Max-Planck-Institut fuer Bioanorganische Chemie, Muelheim an der Ruhr (Germany); H2 Solar GmbH, Loerrach (Germany); Kerpen, Klaus; Kuklya, Andriy; Wuestkamp, Marc-Andre [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany)


    Generation of hydrogen and oxygen from water is described using mainly the semiconductor titanium disilicide as catalyst and halogen light which closely mimics solar radiation. The reactions are carried out under non-aerobic conditions, i.e., under nitrogen. High efficiencies are reached at 1.1-1.2 bar pressure. In the first phase of these reactions the catalytically active centers are built up. During this phase of reaction the kinetics of the water splitting process is growing in and leads to a linear dependence in the further course of the reactions which consists of >96% water splitting to yield hydrogen and oxygen in a 2:1 ratio. Hydrogen is partially and reversibly stored physically, depending on temperature. Oxygen behaves differently since it is stored entirely under the applied reaction conditions (50-80 C and light) and can be liberated from storage upon heating the slurries in the dark. This allows convenient separation of hydrogen and oxygen. The stability of titanium disilicide has been positively tested over several months. This material is abundant and inexpensive besides that it absorbs most of the solar radiation. Further, XRD and XPS studies show that titanium disilicide is 80% crystalline and the oxide formation is limited to a few molecular layers in depth. By using labeled water it was shown that labeled dioxygen appears in the gas phase of such reactions, this showing definitively that hydrogen evolution occuring here stems from photochemical splitting of water. Further, water splitting is part of a project which involves photoelectrochemistry and in which the silicides are used as light-receiving electrode and transition metal-coated anodes serve to split water. (orig.)

  10. Fretting wear behavior of Cr-coated fuel rod for accident-tolerant fuel in flowing fluid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Kim, Hyung Kyu; Kim, Hyun Gil; Koo, Yang Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)


    Fretting wear test of the Cr-coated fuel clading candidate have been performed in the flowing fluid condition in order to verify the reliability of Cr-coated layer on zirconium-based fuel cladding. Rod wear volume at each grid spring and dimple is dramaically increased with GTR gap even though each wear scar is not evenly distributed within a 1x1 grid cell.

  11. Experimental and theoretical study on spray behaviors of modified bio-ethanol fuel employing direct injection system

    Directory of Open Access Journals (Sweden)

    Ghahremani Amirreza


    Full Text Available One of the key solutions to improve engine performance and reduce exhaust emissions of internal combustion engines is direct injection of bio-fuels. A new modified bio-ethanol is produced to be substituted by fossil fuels in gasoline direct injection engines. The key advantages of modified bio-ethanol fuel as an alternative fuel are higher octane number and oxygen content, a long-chain hydro-carbon fuel, and lower emissions compared to fossil fuels. In the present study spray properties of a modified bio-ethanol and its atomization behaviors have been studied experimentally and theoretically. Based on atomization physics of droplets dimensional analysis has been performed to develop a new non-dimensional number namely atomization index. This number determines the atomization level of the spray. Applying quasi-steady jet theory, air entrainment and fuel-air mixing studies have been performed. The spray atomization behaviors such as atomization index number, Ohnesorge number, and Sauter mean diameter have been investigated employing atomization model. The influences of injection and ambient conditions on spray properties of different blends of modified bio-ethanol and gasoline fuels have been investigated performing high-speed visualization technique. Results indicate that decreasing the difference of injection and ambient pressures increases spray cone angle and projected area, and decreases spray tip penetration length. As expected, increasing injection pressure improves atomization behaviors of the spray. Increasing percentage of modified bio-ethanol in the blend, increases spray tip penetration and decreases the projected area as well.

  12. Impact of laser anneal on NiPt silicide texture and chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Feautrier, C.; Ozcan, A. S.; Lavoie, C.; Valery, A.; Beneyton, R.; Borowiak, C.; Clément, L.; Pofelski, A.; Salem, B.


    We have combined synchrotron X-ray pole figure measurements and transmission electron microscopy (TEM) nano-beam diffraction to study the impact of millisecond laser anneal on the texture and microstructure of NiPt silicide thin films. The powerful use of nano-beam diffraction in plan-view geometry allows here for both a mapping of grain orientation and intra-grain measurements even if these crystalline grains become very small. With this unique combination of local and large-scale probes, we find that silicide formation on n and p doped substrates using laser annealing results in smaller grains compared with the films processed using standard rapid thermal annealing. The laser annealed samples also result in grains that are more epitaxially oriented with respect to the Si substrate. For n-type substrate, the film is dominated by (020) and (013) oriented fibers with significant levels of intra-grain bending (transrotation) observed in both types of grains. For p-type substrates, mostly epitaxially aligned grains are detected. TEM coupled with energy-dispersive X-ray analysis was also used to study the elemental distribution in the silicide samples. Here, we confirm that laser anneal leads to a larger accumulation of platinum at the silicide-substrate interface and modifies the distribution of dopants throughout the film.

  13. Role of Ti3Al/silicides on tensile properties of Timetal 834 at various ...

    Indian Academy of Sciences (India)

    Extremely fine coherent precipitates of ordered Ti3Al and relatively coarse incoherent precipitates of 2 silicide exist together in the near -titanium alloy, Timetal 834, in the dual phase matrix of primary and transformed . In order to assess the role of these precipitates, three heat treatments viz. WQ, WQ–A and WQ–OA, ...

  14. Effect of pre-treatment and nickel layer thickness on nickel silicide/silicon carbide contact (United States)

    Cao, Yu; Nyborg, Lars; Jelvestam, Urban; Yi, Danqing


    This investigation deals with the impact of pre-treatment and Ni thickness on the reactions of Ni-silicide/SiC contact fabrication. The specimens have been prepared by sputter depositing 3-100 nm Ni layer on 4H-SiC wafer followed by annealing at 800 °C in vacuum for 20 min. The results by means of XPS show as follows: among the chemical cleaning procedures which have been tested, the recipe NH4OH:H2O2:H2O = 1:1:5, 85 °C, 5 min; HF 10%, 80 °C, 2 min; boiling water 10 min is the most effective for SiC substrates. However, due to short time exposure in the air before experiment, certain contamination re-occurs. After annealing, the dominant silicide formed is Ni2Si, whereas C on the surface is graphite. Argon ion etching before the Ni deposition helps the formation of multi-layer structure. For the samples without pre-treatment or with chemical cleaning procedure, there is more C agglomerated at the surface and no multi-layer structure formed. Under the action of Ar ion etching, SiC decomposes more quickly and Ni diffuses faster. This effect together with limited C diffusivity in the formed silicide is a probable reason for the formation of the multi-layer structure. The silicides formed at the interface are dependent on the Ni layer thickness and substrate surface condition.

  15. Waste Photovoltaic Panels for Ultrapure Silicon and Hydrogen through the Low-Temperature Magnesium Silicide.

    Czech Academy of Sciences Publication Activity Database

    Dytrych, Pavel; Bumba, Jakub; Kaštánek, František; Fajgar, Radek; Koštejn, Martin; Šolcová, Olga


    Roč. 56, č. 45 (2017), s. 12863-12869 ISSN 0888-5885 R&D Projects: GA ČR GA15-14228S Institutional support: RVO:67985858 Keywords : magnesium silicide * waste photovoltaic panels * ultrapure silicon Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.843, year: 2016

  16. High pressure studies on uranium and thorium silicide compounds: Experiment and theory

    DEFF Research Database (Denmark)

    Yagoubi, S.; Heathman, S.; Svane, A.


    The actinide silicides ThSi, USi and USi2 have been studied under high pressure using both theory and experiment. High pressure synchrotron X-ray diffraction experiments were performed on polycrystalline samples in diamond anvil cells at room temperature and for pressures up to 54, 52 and 26 GPa,...

  17. The development of titanium silicide - boron doped polysilicon resistive temperature sensors

    NARCIS (Netherlands)

    Vereshchagina, E.; Vereshchagina, E.; Wolters, Robertus A.M.; Gardeniers, Johannes G.E.


    Thin films of titanium silicide (TiSi2) formed on heavily boron-doped polycrystalline silicon (poly-Si/B+) were applied for the first time for resistive temperature sensing. The temperature sensors exhibited a high-temperature coefficient of resistance of 3.8 × 10−3 ◦C−1, a linear dependence of

  18. Cross-Bridge Kelvin Resistor (CBKR) structures for silicide-semiconductor junctions characterization

    NARCIS (Netherlands)

    Stavitski, N.; van Dal, M.J.H.; Klootwijk, J.H.; Wolters, Robertus A.M.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan


    Analyzing the contact geometry factors for the conventional CBKR structures, it appeared that the contact geometries conventionally used for the metal-to-silicide contact resistance measurements were not always satisfactory to reveal the specific contact resistance values. To investigate these

  19. Role of Ti3Al/silicides on tensile properties of Timetal 834 at various ...

    Indian Academy of Sciences (India)


    conditions. Tensile properties in the above three heat treated conditions were determined at room tempera- ture, 673 K and 873 K. It was observed that largely Ti3Al precipitates were responsible for increase in the yield strength and decrease in ductility in this alloy. Keywords. Near α-titanium alloy; Timetal 834; Ti3Al/silicide ...

  20. Development of a methodology for the evaluation of the thermomechanical behavior of the TRISO fuel

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Lorena P. Rodríguez; Pérez, Daniel Milian; Hernández, Carlos Rafael García; Lorenzo, Daniel E. Milian; Lira, Carlos A. Brayner de Oliveira, E-mail:, E-mail:, E-mail:, E-mail:, E-mail: [Higher Institute of Technologies and Applied Sciences (InSTEC), Habana (Cuba); Universidad Federal de Pernambuco (UFPE), Recife (Brazil). Departamento de Energia Nuclear


    The use of the Generation IV Very High Temperature Reactors (VHTR) presents significant perspectives to assume the future nuclear energy and hydrogen production. VHTR has advantages because its low electricity generation costs, short construction periods, high hydrogen production efficiency, safety and reliability, proliferation resistance and inherent safety features of the fuel and reactor. However, it faces substantial challenges to be successfully deployed as a sustainable energy source. One of these key challenges is the nuclear safety which mainly relies on the quality and integrity of the coated fuel particles (TRISO) planned to be used in these reactors taking into consideration the high temperatures (1000°C in normal operation and up to 1800°C in accidents conditions) and burnup degrees (150 - 200 GWd/tonU) achievable in these reactors. In this paper is presented the current state of development of a methodology for the evaluation of the thermomechanical behavior of the TRISO fuel in function of the variation of different parameters in the VHTR. In order to achieve this goal will be used coupled computational modeling using analytical methods and Monte Carlo and CFD codes such as MCNPX version 2.6e and Ansys version 14. The studies performed in this investigation included the evaluation of key parameters in the TRISO such as the release of fission gases and CO, gas pressure, temperature distributions, kernel migration, maximum stress values, and failure probabilities. The results achieved in this investigation contributes to demonstrating the viability of the proposed methodology for the study, the design and safety calculations of VHTR. (author)

  1. MATPRO-Version 11: a handbook of materials properties for use in the analysis of light water reactor fuel rod behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hagrman, D.L.; Reymann, G.A. (comps.)


    This handbook describes the materials properties correlations and computer subcodes (MATPRO-Version 11) developed for use with various LWR fuel rod behavior analytical programs at the Idaho National Engineering Laboratory. Formulations of fuel rod material properties, which are generally semiempirical in nature, are presented for uranium dioxide and mixed uranium--plutonium dioxide fuel, zircaloy cladding, and fill gas mixtures.

  2. Matpro--version 10: a handbook of materials properties for use in the analysis of light water reactor fuel rod behavior

    Energy Technology Data Exchange (ETDEWEB)

    Reymann, G.A. (comp.)


    The materials properties correlations and computer subcodes (MATPRO--Version 10) developed for use with various LWR fuel rod behavior analytical programs at the Idaho National Engineering Laboratory are described. Formulations of fuel rod material properties, which are generally semiempirical in nature, are presented for uranium dioxide and mixed uranium--plutonium dioxide fuel, zircaloy cladding, and fill gas mixtures.

  3. Adsorption behavior of low concentration carbon monoxide on polymer electrolyte fuel cell anodes for automotive applications (United States)

    Matsuda, Yoshiyuki; Shimizu, Takahiro; Mitsushima, Shigenori


    The adsorption behavior of CO on the anode around the concentration of 0.2 ppm allowed by ISO 14687-2 is investigated in polymer electrolyte fuel cells (PEFCs). CO and CO2 concentrations in the anode exhaust are measured during the operation of a JARI standard single cell at 60 °C cell temperature and 1000 mA cm-2 current density. CO coverage is estimated from the gas analysis and CO stripping voltammetry. The cell voltage decrease as a result of 0.2 ppm CO is 29 mV and the CO coverage is 0.6 at the steady state with 0.11 mg cm-2 of anode platinum loading. The CO coverage as a function of CO concentration approximately follows a Temkin-type isotherm. Oxygen permeated to the anode through a membrane is also measured during fuel cell operation. The exhaust velocity of oxygen from the anode was shown to be much higher than the CO supply velocity. Permeated oxygen should play an important role in CO oxidation under low CO concentration conditions.

  4. Nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Beauvy, M.; Berthoud, G.; Defranceschi, M.; Ducros, G.; Guerin, Y.; Limoge, Y.; Madic, Ch.; Santarini, G.; Seiler, J.M.; Sollogoub, P.; Vernaz, E.; Guillet, J.L.; Ballagny, A.; Bechade, J.L.; Bonin, B.; Brachet, J.Ch.; Delpech, M.; Dubois, S.; Ferry, C.; Freyss, M.; Gilbon, D.; Grouiller, J.P.; Iracane, D.; Lansiart, S.; Lemoine, P.; Lenain, R.; Marsault, Ph.; Michel, B.; Noirot, J.; Parrat, D.; Pelletier, M.; Perrais, Ch.; Phelip, M.; Pillon, S.; Poinssot, Ch.; Vallory, J.; Valot, C.; Pradel, Ph.; Bonin, B.; Bouquin, B.; Dozol, M.; Lecomte, M.; Vallee, A.; Bazile, F.; Parisot, J.F.; Finot, P.; Roberts, J.F


    Fuel is one of the essential components in a reactor. It is within that fuel that nuclear reactions take place, i.e. fission of heavy atoms, uranium and plutonium. Fuel is at the core of the reactor, but equally at the core of the nuclear system as a whole. Fuel design and properties influence reactor behavior, performance, and safety. Even though it only accounts for a small part of the cost per kilowatt-hour of power provided by current nuclear power plants, good utilization of fuel is a major economic issue. Major advances have yet to be achieved, to ensure longer in-reactor dwell-time, thus enabling fuel to yield more energy; and improve ruggedness. Aside from economics, and safety, such strategic issues as use of plutonium, conservation of resources, and nuclear waste management have to be addressed, and true technological challenges arise. This Monograph surveys current knowledge regarding in-reactor behavior, operating limits, and avenues for R and D. It also provides illustrations of ongoing research work, setting out a few noteworthy results recently achieved. Content: 1 - Introduction; 2 - Water reactor fuel: What are the features of water reactor fuel? 9 (What is the purpose of a nuclear fuel?, Ceramic fuel, Fuel rods, PWR fuel assemblies, BWR fuel assemblies); Fabrication of water reactor fuels (Fabrication of UO{sub 2} pellets, Fabrication of MOX (mixed uranium-plutonium oxide) pellets, Fabrication of claddings); In-reactor behavior of UO{sub 2} and MOX fuels (Irradiation conditions during nominal operation, Heat generation, and removal, The processes involved at the start of irradiation, Fission gas behavior, Microstructural changes); Water reactor fuel behavior in loss of tightness conditions (Cladding, the first containment barrier, Causes of failure, Consequences of a failure); Microscopic morphology of fuel ceramic and its evolution under irradiation; Migration and localization of fission products in UOX and MOX matrices (The ceramic under

  5. Rheological behavior of progressively shear-thickening solutions. [aircraft fuel polymer additives for fire protection in survivable crashes (United States)

    Peng, S. T. J.; Landel, R. F.


    The rheological behavior of the recently developed polymer FM-9 in Jet A fuel and JP 8 fuel is reported. In aqueous solution, FM 9 is found to exhibit strong time-dependent shear thickening behavior. Induction time necessary for the onset of thickening is found to depend on shear rate, solvent, concentration, and molecular weight. Altering the nature of the solvent results in effects similar to those obtained by changing the concentration or molecular weight. A critical shear rate is derived, and is inversely proportional to the zero shear rate viscosity of the solution for the temperature and concentrations observed. The onset of shear thickening behavior appears to be related to the onset of viscoelastic response, and thus the time scale follows reduced variable behavior.

  6. The importance of leadership in Soldiers' nutritional behaviors: results from the Soldier Fueling Initiative program evaluation. (United States)

    Jackson, Theresa K; Cable, Sonya J; Jin, Wana K; Robinson, Ayanna; Dennis, Sabriya D; Vo, Linda T; Prosser, Trish J; Rawlings, Jess A


    Improving Soldiers' nutritional habits continues to be a concern of the US Army, especially amidst increasing obesity and high injury rates. This study examines leadership influence on nutritional behaviors within the context of the Soldier Fueling Initiative, a program providing nutrition education and improved dining facility menus to Soldiers in Basic Combat Training (BCT) and Advanced Individual Training (AIT). A mixed methods design using surveys (N=486) and focus groups (N=112) was used to collect data at Fort Jackson, SC, and Fort Eustis, VA, in 2011. Survey results showed 75% of Soldiers in BCT believed their drill sergeant was helpful in making performance-enhancing food choices, and 86% agreed their drill sergeant believed it is important to eat for performance. Soldiers in AIT perceived their cadre as less helpful than their BCT drill sergeants and agreed less frequently that the AIT cadre believed it was important to eat for performance (Pnutritional attitudes and behaviors in both BCT and AIT. Focus groups revealed 5 key themes related to cadre influence and nutrition behavior (listed in order of most to least frequent): (1) cadre influence food choices through consequences related to selection, (2) cadre teach Soldiers how to eat, (3) cadre rush Soldiers to eat quickly to return to training, (4) cadre influence choice through example but often do not make healthy choices, and (5) cadre have no influence on food choices. Leaders influence most Soldiers' nutrition practices within the training environment, particularly within BCT. Given that leader influence can impact Soldiers' attitudes and behaviors, it is critical that military leaders become knowledgeable about optimal nutrition practices to disseminate appropriate information to their Soldiers, avoid reprimand associated with trainees' food choices, reinforce key messages associated with nutrition programming, and lead by example in their own food choices.

  7. Fire behavior, fuel treatments, and fire suppression on the Hayman Fire - Part 3: Effects of fuel treatments on fire severity (United States)

    Erik Martinson; Phillip N. Omi; Wayne Shepperd


    The role played by the fuel conditions within the Hayman Fire severity was complex and does not lend itself to a single conclusion or simple summary. Uncertainties in the original treatment prescription, its implementation, discerning the coverage, extent, and condition at the time of the fire made it difficult for us to clearly determine treatment effects and relate...

  8. Modeling the spatial distribution of forest crown biomass and effects on fire behavior with FUEL3D and WFDS (United States)

    Russell A. Parsons; William Mell; Peter McCauley


    Crown fire poses challenges to fire managers and can endanger fire fighters. Understanding of how fire interacts with tree crowns is essential to informed decisions about crown fire. Current operational crown fire predictions in the United States assume homogeneous crown fuels. While a new class of research fire models, which model fire behavior with computational...

  9. Strategic Placement of Treatments (SPOTS): Maximizing the Effectiveness of Fuel and Vegetation Treatments on Problem Fire Behavior and Effects (United States)

    Diane M. Gercke; Susan A. Stewart


    In 2005, eight U.S. Forest Service and Bureau of Land Management interdisciplinary teams participated in a test of strategic placement of treatments (SPOTS) techniques to maximize the effectiveness of fuel treatments in reducing problem fire behavior, adverse fire effects, and suppression costs. This interagency approach to standardizing the assessment of risks and...

  10. Behavior of spent nuclear fuel and storage system components in dry interim storage. Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A.B. Jr.; Gilbert, E.R.; Guenther, R.J.


    Irradiated nuclear fuel has been handled under dry conditions since the early days of nuclear reactor operation, and use of dry storage facilities for extended management of irradiated fuel began in 1964. Irradiated fuel is currently being stored dry in four types of facilities: dry wells, vaults, silos, and metal casks. Essentially all types of irradiated nuclear fuel are currently stored under dry conditions. Gas-cooled reactor (GCR) and liquid metal fast breeder reactor (LMFBR) fuels are stored in vaults and dry wells. Certain types of fuel are being stored in licensed dry storage facilities: Magnox fuel in vaults in the United Kingdom; organic-cooled reactor (OCR) fuel (clad with a zirconium alloy) in silos in Canada; and boiling water reactor (BWR) fuel (clad with Zircaloy) in a metal storage cask in Germany. Dry storage demonstrations are under way for Zircaloy-clad fuel from BWRs, pressurized heavy-water reactors (PHWRs), and pressurized water reactors (PWRs) in all four types of dry storage facilities. The demonstrations and related hot cell and laboratory tests are directed toward expanding the data base and establishing a licensing basis for dry storage of water reactor fuel. This report reviews the scope of dry interim storage technology, the performance of fuel and facility materials, the status of programs in several countries to license dry storage of water reactor fuel, and the characteristics of water reactor fuel that relate to dry storage conditions. 110 refs., 22 figs., 28 tabs.

  11. Shape modification of Si nanowires by using faceted silicide catalysts nucleated in Au-Si catalyst solution during the growth

    Directory of Open Access Journals (Sweden)

    Erchao Meng


    Full Text Available The shape modification of Si nanowires is demonstrated using faceted solid silicide catalysts. The Si nanowires were grown on Si(111 substrates covered with Au as a catalyst using MnCl2 and Si powders as source materials. The solid silicide catalysts were nucleated and formed in the Au-Si catalyst solution at the top of the nanowires during the growth. The faceted solid silicides grew larger with increased growth time and played a role as a solid catalyst. The faceted shape of the catalyst defines the shape of the faceted Si nanowire. The squared Si nanowires were grown with the growth direction of Si[111] and the sidewalls of {110} and {211} planes. The growth evolution of the faceted Si nanowires occurs by a vapor-liquid-solid mechanism followed by the silicide vapor-solid-solid mechanism.

  12. A fundamental study of the oxidation behavior of SI primary reference fuels with propionaldehyde and DTBP as an additive (United States)

    Johnson, Rodney

    In an effort to combine the benefits of SI and CI engines, Homogeneous Charge Compression Ignition (HCCI) engines are being developed. HCCI combustion is achieved by controlling the temperature, pressure, and composition of the fuel and air mixture so that autoignition occurs in proper phasing with the piston motion. This control system is fundamentally more challenging than using a spark plug or fuel injector to determine ignition timing as in SI and CI engines, respectively. As a result, this is a technical barrier that must be overcome to make HCCI engines applicable to a wide range of vehicles and viable for high volume production. One way to tailor the autoignition timing is to use small amounts of ignition enhancing additives. In this study, the effect of the addition of DTBP and propionaldehyde on the autoignition behavior of SI primary reference fuels was investigated. The present work was conducted in a new research facility built around a single cylinder Cooperative Fuels Research (CFR) octane rating engine but modified to run in HCCI mode. It focused on the effect of select oxygenated hydrocarbons on hydrocarbon fuel oxidation, specifically, the primary reference fuels n-heptane and iso-octane. This work was conducted under HCCI operating conditions. Previously, the operating parameters for this engine were validated for stable combustion under a wide range of operating parameters such as engine speeds, equivalence ratios, compression ratios and inlet manifold temperature. The stable operating range under these conditions was recorded and used for the present study. The major focus of this study was to examine the effect of the addition of DTBP or propionaldehyde on the oxidation behavior of SI primary reference fuels. Under every test condition the addition of the additives DTBP and propionaldehyde caused a change in fuel oxidation. DTBP always promoted fuel oxidation while propionaldehyde promoted oxidation for lower octane number fuels and delayed

  13. Thulium oxide fuel characterization study: Part 2, Environmental behavior and mechanical, thermal and chemical stability enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, C.A.


    A study was performed of the correlation between fuel form stability and exposure environment of (temperature and atmosphere). 100% Tm/sub 2/O/sub 3/, 80% Tm/sub 2/O/sub 3//20% Yb/sub 2/O/sub 3/ and 100% Yb/sub 2/O/sub 3/ wafers were subjected to air, dynamic vacuum and static vacuum at temperatures to 2000/sup 0/C for times to 100 hours. Results showed the Tm/sub 2/O/sub 3//Yb/sub 2/O/sub 3/ cubic structure to be unaffected by elemental levels of iron, aluminum, magnesium and silicon and unaffected by the environmental conditions imposed on the wafers. A second task emphasized the optimization of the thermal, mechanical and chemical stability of Tm/sub 2/O/sub 3/ fuel forms. Enhancement was sought through process variable optimization and the addition of metal oxides to Tm/sub 2/O/sub 3/. CaO, TiO/sub 2/ and Al/sub 2/O/sub 3/ were added to form a grain boundary precipitate to control fines generation. The presence of 1% additive was inadequate to depress the melting point of Tm/sub 2/O/sub 3/ or to change the cubic crystalline structure of Tm/sub 2/O/sub 3//Yb/sub 2/O/sub 3/. Tm/sub 2/O/sub 3//Yb/sub 2/O/sub 3/ wafers containing CaO developed a grain boundary phase that improved the resistance to fines generation. The presence of Yb/sub 2/O/sub 3/ did not appear to measurably influence behavior.

  14. Modeling the effects of different fuel treatment mosaics on wildfire spread and behavior in a Mediterranean agro-pastoral area. (United States)

    Salis, Michele; Del Giudice, Liliana; Arca, Bachisio; Ager, Alan A; Alcasena-Urdiroz, Fermin; Lozano, Olga; Bacciu, Valentina; Spano, Donatella; Duce, Pierpaolo


    Wildfire spread and behavior can be limited by fuel treatments, even if their effects can vary according to a number of factors including type, intensity, extension, and spatial arrangement. In this work, we simulated the response of key wildfire exposure metrics to variations in the percentage of treated area, treatment unit size, and spatial arrangement of fuel treatments under different wind intensities. The study was carried out in a fire-prone 625 km 2 agro-pastoral area mostly covered by herbaceous fuels, and located in Northern Sardinia, Italy. We constrained the selection of fuel treatment units to areas covered by specific herbaceous land use classes and low terrain slope (fuel treatment units for all treatment alternatives. The fuel treatment alternatives were designed create diverse mosaics of disconnected treatment units with different sizes (0.5-10 ha, LOW strategy; 10-25 ha, MED strategy; 25-50 ha, LAR strategy); in addition, treatment units in a 100-m buffer around the road network (ROAD strategy) were tested. We assessed pre- and post-treatment wildfire behavior by the Minimum Travel Time (MTT) fire spread algorithm. The simulations replicated a set of southwestern wind speed scenarios (16, 24 and 32 km h -1 ) and the driest fuel moisture conditions observed in the study area. Our results showed that fuel treatments implemented near the existing road network were significantly more efficient than the other alternatives, and this difference was amplified at the highest wind speed. Moreover, the largest treatment unit sizes were the most effective in containing wildfire growth. As expected, increasing the percentage of the landscape treated and reducing wind speed lowered fire exposure profiles for all fuel treatment alternatives, and this was observed at both the landscape scale and for highly valued resources. The methodology presented in this study can support the design and optimization of fuel management programs and policies in agro

  15. The effects of Ta on the formation of Ni-silicide in Ni{sub 0.95x}Ta{sub x0.05}/Si systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongwon [Department of Ceramic Engineering, Yonsei University, Seoul (Korea, Republic of); Do, Kihoon [Department of Ceramic Engineering, Yonsei University, Seoul (Korea, Republic of); Ko, Dae-Hong [Department of Ceramic Engineering, Yonsei University, Seoul (Korea, Republic of)]. E-mail:; Choi, Siyoung [Process Development Team, Semiconductor R and D Division, Samsung Electronics Ltd. (Korea, Republic of); Ku, Ja-Hum [Process Development Team, Semiconductor R and D Division, Samsung Electronics Ltd. (Korea, Republic of); Yang, Cheol-Woong [School of Metallurgical and Materials Engineering, Sungkyunkwan University Suwon (Korea, Republic of)


    We investigated a comparative study on the silicide formation in the Ni{sub 0.95}Ta{sub 0.05}/Si alloy systems and Ni/Si systems. Ni and Ni{sub 0.95}Ta{sub 0.05} films were deposited on Si(1 0 0) substrate by DC magnetron sputtering and processed at various silicidation temperatures. The sheet resistance of the silicide from the Ni{sub 0.95}Ta{sub 0.05}/Si alloy systems was obtained at lower values than those in pure Ni/Si systems at any temperature. Using RBS and TEM analyses, we confirmed the presence of a Ta rich layer at the top of the Ni-silicide layer and the presence of small amounts of Ta in the silicide layer. The stability of the silicide layer for the Ni{sub 0.95}Ta{sub 0.05} systems is explained by the presence of the Ta rich layer on top of the Ni-silicide layer, as well as by the presence of the small amount of Ta in the Ni-silicide layer. The Ni-silicide using Ni{sub 0.95}Ta{sub 0.05}/Si system displayed a stable sheet resistance value of {approx}5 {omega}/sq which was maintained during the anneal process at 600 deg. C.

  16. Behavior or Nonmetallic Materials in Shale Oil Derived Jet Fuels and in High Aromatic and High Sulfur Petroleum Fuels (United States)


    MATERIAL FUEL (pSi) (MPa) (% Coh) EC-2216 None (controls) 1600 11.0 Base JP-4, .1% sulfur 1710 11.9 40 + 25% arom . , 1% sulfur 1040* 7.2 15 + 35% arom ...1% sulfur ** ** + 45% arom . , 1% sulfur ** ** Synthetic JP-4 1310 9.0 35 Synthetic JET-A 1030 7.1 10 FM-47 None (Controls) 4250 29.3 100 Base JP-4...1% sulfur 3660 25.2 100 + 25% arom .-, 1% sulfur 3490 24.1 100 + 35% arom .-, 1% sulfur 3630 25.0 100 + 45% atom.-, 1% sulfur 3660 25.2 95 Synthetic JP

  17. Study of optical and luminescence properties of silicon — semiconducting silicide — silicon multilayer nanostructures

    Directory of Open Access Journals (Sweden)

    Galkin N.G.


    Full Text Available By method of in situ differential spectroscopy it was established that at the formation of monolayer Fe, Cr, Ca, Mg silicide and Mg stannide islands on the atomically clean silicon surface an appearance of loss peaks characteristic for these materials in the energy range of 1.1-2.6 eV is observed. An optimization of growth processes permit to grow monolithic double nanoheterostructures (DNHS with embedded Fe, Cr and Ca nanocrystals, and also polycrystalline DNHS with NC of Mg silicide and Mg stannide and Ca disilicide. By methods of optical spectroscopy and Raman spectroscopy it was shown that embedded NC form intensive peaks in the reflectance spectra at energies up to 2.5 eV and Raman peaks. In DNS with β-FeSi2 NC a photoluminescence and electroluminescence at room temperature were firstly observed.

  18. Development of a fused slurry silicide coating for the protection of tantalum alloys (United States)

    Packer, C. M.; Perkins, R. A.


    Results are reported of a research program to develop a reliable high-performance, fused slurry silicide protective coating for a tantalum-10 tungsten alloy for use at 1427 to 1538 C at 0.1 to 10 torr air pressure under cyclic temperature conditions. A review of silicide coating performance under these conditions indicated that the primary wear-out mode is associated with widening of hairline fissures in the coating. Consideration has been given to modifying the oxidation products that form on the coating surface to provide a seal for these fissures and to minimize their widening. On the basis of an analysis of the phase relationships between silica and various other oxides, a coating having the slurry composition 2.5Mn-33Ti-64.5Si was developed that is effective in the pressure range from 1 to 10 torr.

  19. Effect of Saturation Pressure Difference on Metal–Silicide Nanopowder Formation in Thermal Plasma Fabrication

    Directory of Open Access Journals (Sweden)

    Masaya Shigeta


    Full Text Available A computational investigation using a unique model and a solution algorithm was conducted, changing only the saturation pressure of one material artificially during nanopowder formation in thermal plasma fabrication, to highlight the effects of the saturation pressure difference between a metal and silicon. The model can not only express any profile of particle size–composition distribution for a metal–silicide nanopowder even with widely ranging sizes from sub-nanometers to a few hundred nanometers, but it can also simulate the entire growth process involving binary homogeneous nucleation, binary heterogeneous co-condensation, and coagulation among nanoparticles with different compositions. Greater differences in saturation pressures cause a greater time lag for co-condensation of two material vapors during the collective growth of the metal–silicide nanopowder. The greater time lag for co-condensation results in a wider range of composition of the mature nanopowder.

  20. Leakage current and deep levels in CoSi{sub 2} silicided junctions

    Energy Technology Data Exchange (ETDEWEB)

    Codegoni, D. [ST Microelectronics Via Olivetti 2, 20041 Agrate Brianza, Milan (Italy); Carnevale, G.P. [ST Microelectronics Via Olivetti 2, 20041 Agrate Brianza, Milan (Italy); De Marco, C. [ST Microelectronics Via Olivetti 2, 20041 Agrate Brianza, Milan (Italy); Mica, I. [ST Microelectronics Via Olivetti 2, 20041 Agrate Brianza, Milan (Italy); Polignano, M.L. [ST Microelectronics Via Olivetti 2, 20041 Agrate Brianza, Milan (Italy)]. E-mail:


    In this work the leakage current of junctions with a self-aligned cobalt silicide is studied. It is shown that junctions with a self-aligned CoSi{sub 2} layer show a leakage current excess which is strongly reduced by increasing the PAI energy. This indicates that the observed leakage current excess is related to the CoSi{sub 2} formation conditions. The mechanism responsible for the leakage of CoSi{sub 2} junctions is investigated by current versus temperature measurements and by deep level transient spectroscopy. In addition, the role of the mechanical stress is investigated by comparing different isolation structures and by numerical stress calculations. It is concluded that the shallow trench isolation (STI) induced stress and the cobalt silicide formation concur to produce a junction leakage current increase by creating a deep level in silicon located close to midgap. This level can possibly identified with a level ascribed to a point defect excess.

  1. Analysis of the behavior under irradiation of high burnup nuclear fuels with the computer programs FRAPCON and FRAPTRAN

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Regis; Silva, Antonio Teixeira e, E-mail: [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)


    The objective of this paper is to verify the validity and accuracy of the results provided by computer programs FRAPCON-3.4a and FRAPTRAN-1.4, used in the simulation process of the irradiation behavior of Pressurized Water Reactors (PWR) fuel rods, in steady-state and transient operational conditions at high burnup. To achieve this goal, the results provided by these computer simulations are compared with experimental data available in the database FUMEX III. Through the results, it was found that the computer programs used have a good ability to predict the operational behavior of PWR fuel rods in high burnup steady-state conditions and under the influence of Reactivity Initiated Accident (RIA). (author)

  2. Fundamental Processes of Coupled Radiation Damage and Mechanical Behavior in Nuclear Fuel Materials for High Temperature Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Phillpot, Simon; Tulenko, James


    The objective of this work has been to elucidate the relationship among microstructure, radiation damage and mechanical properties for nuclear fuel materials. As representative nuclear materials, we have taken an hcp metal (Mg as a generic metal, and Ti alloys for fast reactors) and UO2 (representing fuel). The degradation of the thermo-mechanical behavior of nuclear fuels under irradiation, both the fissionable material itself and its cladding, is a longstanding issue of critical importance to the nuclear industry. There are experimental indications that nanocrystalline metals and ceramics may be more resistant to radiation damage than their coarse-grained counterparts. The objective of this project look at the effect of microstructure on radiation damage and mechanical behavior in these materials. The approach to be taken was state-of-the-art, large-scale atomic-level simulation. This systematic simulation program of the effects of irradiation on the structure and mechanical properties of polycrystalline Ti and UO2 identified radiation damage mechanisms. Moreover, it will provided important insights into behavior that can be expected in nanocrystalline microstructures and, by extension, nanocomposites. The fundamental insights from this work can be expected to help in the design microstructures that are less susceptible to radiation damage and thermomechanical degradation.

  3. Quantifying the effect of fuel reduction treatments on fire behavior in boreal forests (United States)

    B.W. Butler; R.D. Ottmar; T.S. Rupp; R. Jandt; E. Miller; K. Howard; R. Schmoll; S. Theisen; R.E. Vihnanek; D. Jimenez


    Mechanical (e.g., shearblading) and manual (e.g., thinning) fuel treatments have become the preferred strategy of many fire managers and agencies for reducing fire hazard in boreal forests. This study attempts to characterize the effectiveness of four fuel treatments through direct measurement of fire intensity and forest floor consumption during a single prescribed...

  4. Creep analysis of fuel plates for the Advanced Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Swinson, W.F.; Yahr, G.T.


    The reactor for the planned Advanced Neutron Source will use closely spaced arrays of fuel plates. The plates are thin and will have a core containing enriched uranium silicide fuel clad in aluminum. The heat load caused by the nuclear reactions within the fuel plates will be removed by flowing high-velocity heavy water through narrow channels between the plates. However, the plates will still be at elevated temperatures while in service, and the potential for excessive plate deformation because of creep must be considered. An analysis to include creep for deformation and stresses because of temperature over a given time span has been performed and is reported herein.

  5. Fuel Property Blend Model

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mehl, Marco [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wagnon, Scott J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Zhang, Kuiwen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kukkadapu, Goutham [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Westbrook, Charles K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    The object of this project is to develop chemical models and associated correlations to predict the blending behavior of bio-derived fuels when mixed with conventional fuels like gasoline and diesel fuels.

  6. Simulation of tubular solid oxide fuel cell behavior for integration into gas turbine cycles (United States)

    Haynes, Comas Lamar

    Models have been developed and validated for the characterization of tubular solid oxide fuel cells (TSOFCs) and a corresponding fuel cell/gas turbine (FC/GT) power cycle. This promising area of technology is expected to attain near-term commercialization (most notably the SiemensWestinghouse "SureCell" initiative). There is a need for continued conceptual design research in order for the full potential of these systems to be realized. Parametric studies were performed to delineate the impact of cell stack operating conditions on power generation, cell stack thermal management, independent cell load-following and performance quality. The diverse operating conditions included variations in physical cell design, stack pressure, operating voltage, stoichiometric number and stack fuel utilization. A number of novel findings are reported throughout the thesis. As an example, it has been shown that lowering cell stack fuel utilization has a number of benefits for both the simple TSOFC arrangement and the hybrid TSOFC/ GT scenario. The cell stack produces more power at lower fuel utilizations, because fuel supply to the stack actually increases. Additionally, fuel depletion issues (i.e., Nernst potential decrease and smaller limiting currents) are not as influential. A gas turbine bottoming engine would also increase in power production, at lower stack fuel utilizations, because a greater amount of fuel would then fire it. Note that power generation expense is measured per unit rating (e.g., $/kW). Increasing power capacity may then be a means of lowering cost, which is the key obstacle to commercialization. Another cost reduction may stein from the greater contribution of turbomachinery to system power generation, when stack fuel utilization is lowered. FC/GT system efficiency remains stable across a wide domain of cell stack fuel utilizations. This is a result of both the indirect internally reforming (IIR) fuel processor efficiency and Brayton cycle regeneration

  7. The influence of an incomplete fuels treatment on fire behavior and effects in the 2007 Tin Cup Fire, Bitterroot National Forest, Montana (United States)

    Michael Harrington; Erin Noonan-Wright


    Extensive forested areas have received fuels treatments in recent decades and significant funding is available for additional treatments in an attempt to mitigate undesirable high wildfire intensities and impacts. Fuel treatment successes and failures in moderating fire behavior and effects can be found in quantified and anecdotal reports. Questions remain about the...

  8. The effects of bark beetle outbreaks on forest development, fuel loads and potential fire behavior in salvage logged and untreated lodgepole pine forests (United States)

    B. J. Collins; C. C. Rhoades; M. A. Battaglia; R. M. Hubbard


    Recent mountain pine beetle infestations have resulted in widespread tree mortality and the accumulation of dead woody fuels across the Rocky Mountain region, creating concerns over future forest stand conditions and fire behavior. We quantified how salvage logging influenced tree regeneration and fuel loads relative to nearby, uncut stands for 24 lodgepole pine...

  9. An experimental study of the influence of oxygen on silicide formation with tungsten deposited from tungsten hexafluoride (United States)

    Zhang, S.-L.; Smith, U.; Buchta, R.; Östling, M.


    Tungsten disilicide (WSi2) was formed by annealing tungsten films deposited by low-pressure chemical vapor deposition on -silicon substrates. The influence of oxygen on the silicidation rate was studied. Si wafers with different oxygen content in the form of Czochralski, float-zone, and epitaxial wafers were used. Oxygen was also ion implanted into either the silicon substrate or the as-deposited tungsten film. The Rutherford backscattering technique was used to follow the progress of the silicidation. The silicidation rate was found to be dependent on the oxygen content of the Si substrates. The rate was lowest for Czochralski substrates and highest for float-zone substrates. Secondary ion mass spectroscopy was used to study the oxygen and fluorine profiles in the films prior to and after silicidation. Growth of WSi2 was found to be retarded concurrently with a pile-up of fluorine at the tungsten side of the W/WSi2 interface and a gettering of oxygen from the annealing atmosphere at the interface. Growth of WSi2 was then transferred to the tungsten surface. Oxygen implantation into silicon and tungsten, respectively, reduced the rate of silicide formation. Oxygen implantation into tungsten altered the distribution of fluorine and suppressed WSi2 growth at the tungsten surface. The observations led to a conceptual model, which ascribes the retardation in the growth of the inner WSi2 to a``poisoning'' effect caused by the increase of oxygen and fluorine levels at the interface.

  10. Using fine-scale fuel measurements to assess wildland fuels, potential fire behavior and hazard mitigation treatments in the southeastern USA (United States)

    Roger D. Ottmar; John I. Blake; William T. Crolly


    The inherent spatial and temporal heterogeneity of fuel beds in forests of the southeastern United States may require fine scale fuel measurements for providing reliable fire hazard and fuel treatment effectiveness estimates. In a series of five papers, an intensive, fine scale fuel inventory from the Savanna River Site in the southeastern United States is used for...

  11. Probing Transition-Metal Silicides as PGM-Free Catalysts for Hydrogen Oxidation and Evolution in Acidic Medium (United States)

    Mittermeier, Thomas; Madkikar, Pankaj; Wang, Xiaodong; Gasteiger, Hubert A.; Piana, Michele


    In this experimental study, we investigate various transition-metal silicides as platinum-group-metal-(PGM)-free electrocatalysts for the hydrogen oxidation reaction (HOR), and for the hydrogen evolution reaction (HER) in acidic environment for the first time. Using cyclic voltammetry in 0.1 M HClO4, we first demonstrate that the tested materials exhibit sufficient stability against dissolution in the relevant potential window. Further, we determine the HOR and HER activities for Mo, W, Ta, Ni and Mo-Ni silicides in rotating disk electrode experiments. In conclusion, for the HOR only Ni2Si shows limited activity, and the HER activity of the investigated silicides is considerably lower compared to other PGM-free HER catalysts reported in the literature. PMID:28773022

  12. Temperature and Stress Simulation of 4H-SiC during Laser-Induced Silicidation for Ohmic Contact Generation

    Directory of Open Access Journals (Sweden)

    Benedikt Adelmann


    Full Text Available We report here on the simulation of temperature and stress evolution of 4H-SiC during laser-induced silicidation to locally generate ohmic contacts between the semiconductor and nickel metallization. The simulation is based on optical free carrier absorption, thermal conduction, and thermal radiation. Our results show that, during laser irradiation, similar temperatures and correspondingly similar contact resistances, as compared to conventional oven-driven annealing processes, are achievable, yet with the advantageous potential to limit the temperature treatment spatially to the desired regions for electrical contacts and without the necessity of heating complete wafers. However, due to temperature gradients during local laser silicidation, thermal induced stress appears, which may damage the SiC wafer. Based on the simulated results for temperature and stress increase, we identify an optimized regime for laser-induced local silicidation and compare it to experimental data and observations.

  13. Characterization and Detailed Analysis of Regression Behavior for HTPB Solid Fuels Containing High Aluminum Loadings (United States)

    Kibbey, Timothy P.; Cortopassi, Andrew C.; Boyer, Eric C.


    NASA Marshall Space Flight Center's Materials and Processes Department, with support from the Propulsion Systems Department, has renewed the development and maintenance of a hybrid test bed for exposing ablative thermal protection materials to an environment similar to that seen in solid rocket motors (SRM). The Solid Fuel Torch (SFT), operated during the Space Shuttle program, utilized gaseous oxygen for oxidizer and an aluminized hydroxyl-terminated polybutadiene (HTPB) fuel grain to expose a converging section of phenolic material to a 400 psi, 2-phase flow combustion environment. The configuration allows for up to a 2 foot long, 5 inch diameter fuel grain cartridge. Wanting to now test rubber insulation materials with a turn-back feature to mimic the geometry of an aft dome being impinged by alumina particles, the throat area has now been increased by several times to afford flow similarity. Combined with the desire to maintain a higher operating pressure, the oxidizer flow rate is being increased by a factor of 10. Out of these changes has arisen the need to characterize the fuel/oxidizer combination in a higher mass flux condition than has been previously tested at MSFC, and at which the literature has little to no reporting as well. For (especially) metalized fuels, hybrid references have pointed out possible dependence of fuel regression rate on a number of variables: mass flux, G - oxidizer only (G0), or - total mass flux (Gtot), Length, L, Pressure, P, and Diameter, D.

  14. Intercalation synthesis of graphene-capped iron silicide atop Ni(111): Evolution of electronic structure and ferromagnetic ordering

    Energy Technology Data Exchange (ETDEWEB)

    Grebenyuk, G.S. [Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Vilkov, O.Yu.; Rybkin, A.G. [St. Petersburg State University, 199034 St. Petersburg (Russian Federation); Gomoyunova, M.V. [Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Senkovskiy, B.V. [St. Petersburg State University, 199034 St. Petersburg (Russian Federation); II. Physikalisches Institut, Universität zu Köln, D-50937 Cologne (Germany); Usachov, D.Yu. [St. Petersburg State University, 199034 St. Petersburg (Russian Federation); Vyalikh, D.V. [St. Petersburg State University, 199034 St. Petersburg (Russian Federation); Institute of Solid State Physics, Dresden University of Technology, 01062 Dresden (Germany); Molodtsov, S.L. [European XFEL GmbH, 22761 Hamburg (Germany); Institute of Experimental Physics, Technische Universität Bergakademie Freiberg, 09599 Freiberg (Germany); ITMO University, 197101 St. Petersburg (Russian Federation); Pronin, I.I., E-mail: [Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); ITMO University, 197101 St. Petersburg (Russian Federation)


    Highlights: • Evolution of Graphene/Ni system due to intercalation with Fe and Si is studied. • Graphene strongly interacts with the topmost atoms of the intercalated fcc Fe film. • The in-plane ferromagnetic ordering of the film arises after intercalation of 5 ML Fe. • Fe-Si solid solution and Fe{sub 3}Si surface silicide are formed after intercalation of Si. • The capping graphene layer is weakly electronically coupled to the silicide phase. - Abstract: A new method for synthesis of graphene-protected iron silicides has been tested, which consists in formation of graphene on Ni(111) followed by two-step intercalation of the system with Fe and Si. Characterization of the samples was performed in situ by low-energy electron diffraction, angular-resolved photoelectron spectroscopy, core-level photoelectron spectroscopy with synchrotron radiation and magnetic linear dichroism in photoemission of Fe 3p electrons. It is shown, that at 400 °C the intercalation of graphene/Ni(111) with iron occurs in a range up to 14 ML. The graphene layer strongly interacts with the topmost Fe atoms and stabilizes the fcc structure of the film. The in-plane ferromagnetic ordering of the film has a threshold nature and arises after the intercalation of 5 ML Fe due to the thickness-driven spin reorientation transition. Subsequent intercalation of graphene/Fe/Ni(111) with Si leads to the formation of the inhomogeneous system consisted of intercalated and nonintercalated areas. The intercalated islands coalesce at 2 ML Si when a Fe-Si solid solution covered with the Fe{sub 3}Si surface silicide is formed. The Fe{sub 3}Si silicide is ferromagnetic and has an ordered (√3 × √3)R30° structure. The graphene layer is weakly electronically coupled to the silicide phase keeping its remarkable properties ready for use.

  15. Formation, optical properties, and electronic structure of thin Yb silicide films on Si(111) (United States)

    Galkin, N. G.; Maslov, A. M.; Polyarnyi, V. O.


    Continuous very thin (2.5-3.0 nm) and thin (16-18 nm) ytterbium suicide films with some pinhole density (3×107- 1×108 cm-2) have been formed on Si(111) by solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE) growth methods on templates. The stoichiometric ytterbium suicide (YbSi2) formation has shown in SPE grown films by AES and EELS data. Very thin Yb suicide films grown by RDE method had the silicon enrichment in YbSi2 suicide composition. The analysis of LEED data and AFM imaging has shown that ytterbium suicide films had non-oriented blocks with the polycrystalline structure. The analysis of scanning region length dependencies of the root mean square roughness deviation (σR(L)) for grown suicide films has shown that the formation of ytterbium suicide in SPE and RDE growth methods is determined by the surface diffusion of Yb atoms during the three-dimensional growth process. Optical functions (n, k, α, ɛ1, ɛ2, Im ɛ1-1, neff, ɛeff) of ytterbium silicide films grown on Si(1 1 1) have been calculated from transmittance and reflectance spectra in the energy range of 0.1-6.2 eV. Two nearly discrete absorption bands have been observed in the electronic structure of Yb silicide films with different composition, which connected with interband transitions on divalent and trivalent Yb states. It was established that the reflection coefficient minimum in R-spectra at energies higher 4.2 eV corresponds to the state density minimum in Yb suicide between divalent and trivalent Yb states. It was shown from optical data that Yb silicide films have the semi-metallic properties with low state densities at energies less 0.4 eV and high state densities at 0.5-2.5 eV.

  16. Combustion synthesis of molybdenum silicides and borosilicides for ultrahigh-temperature structural applications (United States)

    Alam, Mohammad Shafiul

    Molybdenum silicides and borosilicides are promising structural materials for gas-turbine power plants. A major challenge, however, is to simultaneously achieve high oxidation resistance and acceptable mechanical properties at high temperatures. For example, molybdenum disilicide (MoSi2) has excellent oxidation resistance and poor mechanical properties, while Mo-rich silicides such as Mo5Si3 (called T 1) have much better mechanical properties but poor oxidation resistance. One approach is based on the fabrication of MoSi2-T 1 composites that combine high oxidation resistance of MoSi2 and good mechanical properties of T1. Another approach involves the addition of boron to Mo-rich silicides for improving their oxidation resistance through the formation of a borosilicate surface layer. In particular, Mo 5SiB2 (called T2) phase is considered as an attractive material. In the thesis, MoSi2-T1 composites and materials based on T2 phase are obtained by mechanically activated SHS. Use of SHS compaction (quasi-isostatic pressing) significantly improves oxidation resistance of the obtained MoSi2-T1 composites. Combustion of Mo-Si-B mixtures for the formation of T2 phase becomes possible if the composition is designed for the addition of more exothermic reactions leading to the formation of molybdenum boride. These mixtures exhibit spin combustion, the characteristics of which are in good agreement with the spin combustion theory. Oxidation resistance of the obtained Mo-Si-B materials is independent on the concentration of Mo phase in the products so that the materials with a higher Mo content are preferable because of better mechanical properties. Also, T2 phase has been obtained by the chemical oven combustion synthesis technique.

  17. X-ray photoemission spectromicroscopy of titanium silicide formation in patterned microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.; Solak, H.; Cerrina, F. [Univ. of Wisconsin-Madison, Stoughton, WI (United States)] [and others


    Titanium silicide has the lowest resistivity of all the refractory metal silicides and has good thermal stability as well as excellent compatibility with Al metallization. It is used as an intermediate buffer layer between W vias and the Si substrate to provide good electrical contact in ULSI technology, whose submicron patterned features form the basis of the integrated circuits of today and tomorrow, in the self aligned silicide (salicide) formation process. TiSi{sub 2} exists in two phases: a metastable C49 base-centered orthorhombic phase with specific resistivity of 60-90 {mu}{Omega}-cm that is formed at a lower temperature (formation anneal) and the stable 12-15 {mu}{Omega}-cm resistivity face-centered orthorhombic C54 phase into which C49 is transformed with a higher temperature (conversion anneal) step. C54 is clearly the target for low resistivity VLSI interconnects. However, it has been observed that when dimensions shrink below 1/mic (or when the Ti thickness drops below several hundred angstroms), the transformation of C49 into C54 is inhibited and agglomeration often occurs in fine lines at high temperatures. This results in a rise in resistivity due to incomplete transformation to C54 and because of discontinuities in the interconnect line resulting from agglomeration. Spectromicroscopy is an appropriate tool to study the evolution of the TiSi2 formation process because of its high resolution chemical imaging ability which can detect bonding changes even in the absence of changes in the relative amounts of species and because of the capability of studying thick {open_quotes}as is{close_quotes} industrial samples.

  18. In situ, real-time characterization of silicide nanostructure coarsening dynamics by photo-electron emission microscopy (United States)

    Zeman, Matthew Casimir

    Photo-electron emission microscopy (PEEM) was used to observe the growth and coarsening dynamics of transition metal (TM) silicide and rare earth (RE) silicide nanostructures on silicon surfaces in real-time with high lateral resolution during in situ annealing. Evidence was obtained indicating that the coarsening of the silicide islands is strongly influenced by local variations in the size, shape, and number of nanostructures on the surface. The titanium, hafnium, and zirconium silicide nanostructures were observed to grow via Ostwald ripening and attractive migration and coalescence (AMC) at temperatures as high as ~1200°C. Ostwald ripening is a classic coarsening process in which larger nanostructures grow at the expense of smaller surrounding structures as per the Gibbs-Thompson relation. Attractive migration and coalescence is a newly discovered coarsening pathway where nearby islands are observed to migrate attractively towards each other and subsequently coalesce in response to local adatom concentration variations on the surface. A shape distortion of the normally compact and rounded TM silicide islands has been observed during these coarsening processes. The shape distortion suggests that the nanostructures are exchanging mass with each other via diffusion limited processes and these observations support the AMC model. The dysprosium and erbium silicide nanostructures exhibit a distinct faceted morphology and primarily coarsen via Ostwald ripening. The RE silicides form highly elongated nanowires and compact rectangular nanostructures on Si(001) and triangular or hexagonal structures on Si(111). We show that the wires are metastable structures which decay in favor of the larger rectangular islands at high temperatures. Additionally, the rectangular shape and faceted morphology of the RE silicide nanostructures strongly influences their coarsening dynamics. A separate PEEM study explored the thermal stability of thin films of TM oxides (TiO2, ZrO2, HfO2

  19. Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

    KAUST Repository

    Bahabry, R. R.


    We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

  20. Evaluation of anomalies during nickel and titanium silicide formation using the effective heat of formation mode

    CSIR Research Space (South Africa)

    Pretorius, R


    Full Text Available stream_source_info pretorius_1993.pdf.txt stream_content_type text/plain stream_size 39978 Content-Encoding ISO-8859-1 stream_name pretorius_1993.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Materials Chemistry... and Physics, 36 (1993) 31-38 31 Evaluation of anomalies during nickel and titanium silicide formation using the effective heat of formation model R. Pretorius, C.C. Theron IonSolid Znteraction Division, Van de H.A. Ras and T...

  1. On the structural and electronic properties of Ir-silicide nanowires on Si(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Fatima,; Hossain, Sehtab; Mohottige, Rasika; Oncel, Nuri, E-mail:, E-mail: [Department of Physics and Astrophysics, University of North Dakota, Grand Forks, North Dakota 58202 (United States); Can Oguz, Ismail; Gulseren, Oguz, E-mail:, E-mail: [Department of Physics, Bilkent University, Ankara (Turkey); Çakır, Deniz [Department of Physics, University of Antwerp, Antwerp 2610 (Belgium)


    Iridium (Ir) modified Silicon (Si) (001) surface is studied with Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and Density Functional Theory (DFT). A model for Ir-silicide nanowires based on STM images and ab-initio calculations is proposed. According to our model, the Ir adatom is on the top of the substrate dimer row and directly binds to the dimer atoms. I-V curves measured at 77 K shows that the nanowires are metallic. DFT calculations confirm strong metallic nature of the nanowires.

  2. Effect of stress evolution on microstructural behavior in U-Mo/Al dispersion fuel (United States)

    Jeong, G. Y.; Kim, Yeon Soo; Jamison, L. M.; Robinson, A. B.; Lee, K. H.; Sohn, Dong-Seong


    U-Mo/Al dispersion fuel irradiated to high burnup at high power (high fission rate) exhibited microstructural changes including deformation of the fuel particles, pore growth, and rupture of the Al matrix. The driving force for these microstructural changes was meat swelling resulting from a combination of fuel particle swelling and interaction layer (IL) growth. In some cases, pore growth in the interaction layers also contributed to meat swelling. The main objective of this work was to determine the stress distribution within the fuel meat that caused these phenomena. A mechanical equilibrium between the stress generated by fuel meat swelling and the stress relieved by fission-induced creep in the meat constituents (U-Mo particles, Al matrix, and IL) was considered. Test plates with well-recorded fabrication data and irradiation conditions were used, and their post-irradiation examination (PIE) data was obtained. ABAQUS finite element analysis (FEA) was utilized to simulate the microstructural evolution of the plates. The simulation results allowed for the determination of effective stress and hydrostatic stress exerted on the meat constituents. The effects of fabrication and irradiation parameters on the stress distribution that drives microstructural evolutions, such as pore growth in the IL and Al matrix rupture, were investigated.

  3. Modelling Accident Tolerant Fuel Concepts

    Energy Technology Data Exchange (ETDEWEB)

    Hales, Jason Dean [Idaho National Laboratory; Gamble, Kyle Allan Lawrence [Idaho National Laboratory


    The catastrophic events that occurred at the Fukushima-Daiichi nuclear power plant in 2011 have led to widespread interest in research of alternative fuels and claddings that are proposed to be accident tolerant. The United States Department of Energy (DOE) through its Nuclear Energy Advanced Modeling and Simulation (NEAMS) program has funded an Accident Tolerant Fuel (ATF) High Impact Problem (HIP). The ATF HIP is a three-year project to perform research on two accident tolerant concepts. The final outcome of the ATF HIP will be an in-depth report to the DOE Advanced Fuels Campaign (AFC) giving a recommendation on whether either of the two concepts should be included in their lead test assembly scheduled for placement into a commercial reactor in 2022. The two ATF concepts under investigation in the HIP are uranium silicide fuel and iron-chromium-aluminum (FeCrAl) alloy cladding. Utilizing the expertise of three national laboratory participants (Idaho National Laboratory, Los Alamos National Laboratory, and Argonne National Laboratory), a comprehensive multiscale approach to modeling is being used that includes atomistic modeling, molecular dynamics, rate theory, phase-field, and fuel performance simulations. Model development and fuel performance analysis are critical since a full suite of experimental studies will not be complete before AFC must prioritize concepts for focused development. In this paper, we present simulations of the two proposed accident tolerance fuel systems: U3Si2 fuel with Zircaloy-4 cladding, and UO2 fuel with FeCrAl cladding. Sensitivity analyses are completed using Sandia National Laboratories’ Dakota software to determine which input parameters (e.g., fuel specific heat) have the greatest influence on the output metrics of interest (e.g., fuel centerline temperature). We also outline the multiscale modelling approach being employed. Considerable additional work is required prior to preparing the recommendation report for the Advanced

  4. Behavior of spent fuel and cask components after extended periods of dry storage

    Energy Technology Data Exchange (ETDEWEB)

    Kenneally, R. [U.S. Nuclear Regulatory Commission, Rockville, MD (United States); Kessler, J. [Electric Power Research Inst., Palo Alto, CA (United States)


    The U.S. Nuclear Regulatory Commission (NRC) promulgated 10 CFR Part 72, Title 10, for the independent storage of spent nuclear fuel and high-level radioactive waste outside reactor spent fuel pools. Part 72 currently limits the license term for an independent spent fuel storage installation to 20 years from the date of issuance. Licenses may be renewed by the Commission at or before the expiration of the license term. Applications for renewal of a license should be filed at least two years prior to the expiration of the existing license. In preparation for possible license renewal, the NRC Office of Nuclear Material and Safeguards, Spent Fuel Project Office, is developing the technical basis for renewals of licenses and Certificates of Compliance for dry storage systems for spent nuclear fuel and high-level radioactive waste at independent spent fuel storage installation sites. An analysis of past performance of selected components of these systems is required as part of that technical basis. In the years 1980 through the early 1990, the Department of Energy (DOE) procured four prototype dry storage casks for testing at the Idaho National Engineering and Environmental Laboratory (INEEL): Castor-V/21, MC-10, TN-24P, and VSC-17. The primary purpose of the testing was to benchmark thermal and radiological codes and to determine the thermal and radiological characteristics of the casks. A series of examinations in 1999 and early 2000 to investigate the integrity of the Castor V/21 cask were undertaken. There is no evidence of significant degradation of the Castor V/21 cask systems important to safety from the time of initial loading of the cask in 1985 up to the time of testing in 1999. (author)

  5. Simulations of flow behavior of fuel particles in a conceptual helium-cooled spout fluidized bed nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wang Shuyan; Li Xiang [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Lu Huilin [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)], E-mail:; Bouillard, Jacques [INERIS, Parc Technologique Alata, BP2, Verneuil-en-Halatte 60550 (France); Sun Qiaoqun; Wang Shuai [School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)


    Hydrodynamics of helium and fuel particles are simulated in a conceptual helium-cooled spout fluidized bed nuclear reactor. The conceptual reactor consists of an axis-symmetric column with a sharp cone inside which the fuel particles are fluidized by helium. An isothermal gas-solid two-fluid flow model is presented. The kinetic-frictional constitutive model for dense assemblies of solids is incorporated. The kinetic stress is modeled using the kinetic theory of granular flow, while the friction stress is from the normal frictional stress model proposed by (Johnson, P.C., Nott, P., Jackson, R., 1990. Frictional-collisional equations of motion for particulate flows and their application to chutes. Journal of Fluid Mechanics 210, 501-535). Detailed spatial/temporal concentration and velocity profiles have been obtained in a conceptual spout fluidized bed nuclear reactor. The influence of inlet spouting jet velocity and conical angles on flow behavior of fluid and fuel particles is analyzed. The numerical simulations show that the unique mixing ability of the spout fluidized bed nuclear reactor gives rise, as expected, to uniform particle distributions. This uniformity enhances the heat transfer and therefore the power produced by the reactor.

  6. Physical characteristics of shrub and conifer fuels for fire behavior models (United States)

    Jonathan R. Gallacher; Thomas H. Fletcher; Victoria Lansinger; Sydney Hansen; Taylor Ellsworth; David R. Weise


    The physical properties and dimensions of foliage are necessary inputs for some fire spread models. Currently, almost no data exist on these plant characteristics to fill this need. In this report, we measured the physical properties and dimensions of the foliage from 10 live shrub and conifer fuels throughout a 1-year period. We developed models to predict relative...

  7. How fuel treatment types, locations, and amounts impact landscape-scale fire behavior and carbon dynamics (United States)

    Christopher A. Dicus; Kevin J. Osborne


    When managing for fire across a large landscape, the types of fuel treatments, the locations of treatments, and the percentage of the landscape being treated should all interact to impact not only potential fire size, but also carbon dynamics across that landscape. To investigate these interactions, we utilized a forest growth model (FVS-FFE) and fire simulation...

  8. Fuels planning: science synthesis and integration; social issues fact sheet 02: Developing personal responsibility for fuels reduction: Types of information to encourage proactive behavior (United States)

    Rocky Mountain Research Station USDA Forest Service


    Fuels management responsibilities may include providing local property owners with the information for taking responsibility for reducing fuels on their land. This fact sheet discusses three different types of information that may be useful in programs to engage property owners in fuel reduction activities.

  9. Impact of Nickel silicide Rear Metallization on Series Resistance of Crystalline Silicon Solar Cells

    KAUST Repository

    Bahabry, Rabab R


    The Silicon-based solar cell is one of the most important enablers toward high efficiency and low-cost clean energy resource. Metallization of silicon-based solar cells typically utilizes screen printed silver-Aluminium (Ag-Al) which affects the optimal electrical performance. To date, metal silicide-based ohmic contacts are occasionally used as an alternative candidate only to the front contact grid lines in crystalline silicon (c-Si) based solar cells. In this paper, we investigate the electrical characteristics of nickel mono-silicide (NiSi)/Cu-Al ohmic contact on the rear side of c-Si solar cells. We observe a significant enhancement in the fill factor of around 6.5% for NiSi/Cu-Al rear contacts leading to increasing the efficiency by 1.2% compared to Ag-Al. This is attributed to the improvement of the parasitic resistance in which the series resistance decreased by 0.737 Ω.cm². Further, we complement experimental observation with a simulation of different contact resistance values, which manifests NiSi/Cu-Al rear contact as a promising low-cost metallization for c-Si solar cells with enhanced efficiency.

  10. Magnesium and Manganese Silicides For Efficient And Low Cost Thermo-Electric Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Trivedi, Sudhir B. [Brimrose Technology Corporation; Kutcher, Susan W. [Brimrose Technology Corporation; Rosemeier, Cory A. [Brimrose Technology Corporation; Mayers, David [Brimrose Technology Corporation; Singh, Jogender [Pennsylvania State University


    Thermoelectric Power Generation (TEPG) is the most efficient and commercially deployable power generation technology for harvesting wasted heat from such things as automobile exhausts, industrial furnaces, and incinerators, and converting it into usable electrical power. We investigated the materials magnesium silicide (Mg2Si) and manganese silicide (MnSi) for TEG. MgSi2 and MnSi are environmentally friendly, have constituent elements that are abundant in the earth's crust, non-toxic, lighter and cheaper. In Phase I, we successfully produced Mg2Si and MnSi material with good TE properties. We developed a novel technique to synthesize Mg2Si with good crystalline quality, which is normally very difficult due to high Mg vapor pressure and its corrosive nature. We produced n-type Mg2Si and p-type MnSi nanocomposite pellets using FAST. Measurements of resistivity and voltage under a temperature gradient indicated a Seebeck coefficient of roughly 120 V/K on average per leg, which is quite respectable. Results indicated however, that issues related to bonding resulted in high resistivity contacts. Determining a bonding process and bonding material that can provide ohmic contact from room temperature to the operating temperature is an essential part of successful device fabrication. Work continues in the development of a process for reproducibly obtaining low resistance electrical contacts.

  11. Silicon-germanium and platinum silicide nanostructures for silicon based photonics (United States)

    Storozhevykh, M. S.; Dubkov, V. P.; Arapkina, L. V.; Chizh, K. V.; Mironov, S. A.; Chapnin, V. A.; Yuryev, V. A.


    This paper reports a study of two types of silicon based nanostructures prospective for applications in photonics. The first ones are Ge/Si(001) structures forming at room temperature and reconstructing after annealing at 600°C. Germanium, being deposited from a molecular beam at room temperature on the Si(001) surface, forms a thin granular film composed of Ge particles with sizes of a few nanometers. A characteristic feature of these films is that they demonstrate signs of the 2 x 1 structure in their RHEED patterns. After short-term annealing at 600°C under the closed system conditions, the granular films reconstruct to heterostructures consisting of a Ge wetting layer and oval clusters of Ge. A mixed type c(4x2) + p(2x2) reconstruction typical to the low-temperature MBE (Tgr class of materials is one of the friendliest to silicon technology. But as silicide film thickness reaches a few nanometers, low resistivity becomes of primary importance. Pt3Si has the lowest sheet resistance among the Pt silicides. However, the development of a process of thin Pt3Si films formation is a challenging task. This paper describes formation of a thin Pt3Si/Pt2Si structures at room temperature on poly-Si films. Special attention is paid upon formation of poly-Si and amorphous Si films on Si3N4 substrates at low temperatures.

  12. Prediction of Stable Ruthenium Silicides from First-Principles Calculations: Stoichiometries, Crystal Structures, and Physical Properties. (United States)

    Zhang, Chuanzhao; Kuang, Xiaoyu; Jin, Yuanyuan; Lu, Cheng; Zhou, Dawei; Li, Peifang; Bao, Gang; Hermann, Andreas


    We present results of an unbiased structure search for stable ruthenium silicide compounds with various stoichiometries, using a recently developed technique that combines particle swarm optimization algorithms with first-principles calculations. Two experimentally observed structures of ruthenium silicides, RuSi (space group P2(1)3) and Ru2Si3 (space group Pbcn), are successfully reproduced under ambient pressure conditions. In addition, a stable RuSi2 compound with β-FeSi2 structure type (space group Cmca) was found. The calculations of the formation enthalpy, elastic constants, and phonon dispersions demonstrate the Cmca-RuSi2 compound is energetically, mechanically, and dynamically stable. The analysis of electronic band structures and densities of state reveals that the Cmca-RuSi2 phase is a semiconductor with a direct band gap of 0.480 eV and is stabilized by strong covalent bonding between Ru and neighboring Si atoms. On the basis of the Mulliken overlap population analysis, the Vickers hardness of the Cmca structure RuSi2 is estimated to be 28.0 GPa, indicating its ultra-incompressible nature.

  13. Preliminary investigations on the use of uranium silicide targets for fission Mo-99 production

    Energy Technology Data Exchange (ETDEWEB)

    Cols, H.; Cristini, P.; Marques, R.


    The National Atomic Energy Commission (CNEA) of Argentine Republic owns and operates an installation for production of molybdenum-99 from fission products since 1985, and, since 1991, covers the whole national demand of this nuclide, carrying out a program of weekly productions, achieving an average activity of 13 terabecquerel per week. At present they are finishing an enlargement of the production plant that will allow an increase in the volume of production to about one hundred of terabecquerel. Irradiation targets are uranium/aluminium alloy with 90% enriched uranium with aluminium cladding. In view of international trends held at present for replacing high enrichment uranium (HEU) for enrichment values lower than 20 % (LEU), since 1990 the authors are in contact with the RERTR program, beginning with tests to adapt their separation process to new irradiation target conditions. Uranium silicide (U{sub 3}Si{sub 2}) was chosen as the testing material, because it has an uranium mass per volume unit, so that it allows to reduce enrichment to a value of 20%. CNEA has the technology for manufacturing miniplates of uranium silicide for their purposes. In this way, equivalent amounts of Molybdenum-99 could be obtained with no substantial changes in target parameters and irradiation conditions established for the current process with Al/U alloy. This paper shows results achieved on the use of this new target.

  14. Plasma-enhanced deposition and processing of transition metals and transition metal silicides for VLSI (United States)

    Hess, D. W.


    Radiofrequency (rf) discharges have been used to deposit films of tungsten, molybdenum and titanium silicide. As-deposited tungsten films, from tungsten hexafluoride and hydrogen source gases, were metastable (beta W), with significant (>1 atomic percent) fluorine incorporation. Film resistivities were 40-55 micro ohm - cm due to the beta W, but dropped to about 8 micro ohm cm after a short heat treatment at 700 C which resulted in a phase transition to alpha W (bcc form). The high resistivity (>10,000 micro ohm) associated with molybdenum films deposited from molybdenum hexafluoride and hydrogen appeared to be a result of the formation of molybdenum trifluoride in the deposited material. Titanium silicide films formed from a discharge of titanium tetrachloride, silane, and hydrogen, displayed resistivities of about 150 micro ohm cm, due to small amounts of oxygen and chlorine incorporated during deposition. Plasma etching studies of tungsten films with fluorine containing gases suggest that the etchant species for tungsten in these discharges are fluorine atoms.

  15. Two-dimensional electronic structure of dysprosium silicide nanowires on Si(557)

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, Martina; Loeser, Karolin; Pruskil, Gerd; Daehne, Mario [Institute of Solid State Physics, Technical University Berlin (Germany); Stojanov, Petar; Huwald, Eric; Riley, John [School of Physics, La Trobe University, Bundoora, VIC (Australia)


    Rare earth silicide nanostructures are of high interest because of their extremely low Schottky barriers on n-Si(111) and the formation of nanowires with one-dimensional metallicity on Si(001). In this work, the self-organized growth of monolayer-thick dysprosium silicide nanowires on Si(557) has been studied by scanning tunnelling microscopy and angle-resolved photoelectron spectroscopy. The bare Si(557) surface is characterized by (111) and (112) facets. Accordingly, we observed the nanowires forming on the (111) facets. For coverages of 2A dysprosium, nanowire lengths exceeding 1{mu}m and widths around 5 nm were found. Their electronic structure shows a strong dispersion both parallel and perpendicular to the nanowires, which is assigned to the band structure of DySi{sub 2} monolayers on Si(111). At higher coverages similar nanowires are observed at the (111) facets, which show characteristic structural properties of the multilayer growth and also the Dy{sub 3}Si{sub 5} multilayer band structure.

  16. Fabrication of Ni-silicide/Si heterostructured nanowire arrays by glancing angle deposition and solid state reaction (United States)


    This work develops a method for growing Ni-silicide/Si heterostructured nanowire arrays by glancing angle Ni deposition and solid state reaction on ordered Si nanowire arrays. Samples of ordered Si nanowire arrays were fabricated by nanosphere lithography and metal-induced catalytic etching. Glancing angle Ni deposition deposited Ni only on the top of Si nanowires. When the annealing temperature was 500°C, a Ni3Si2 phase was formed at the apex of the nanowires. The phase of silicide at the Ni-silicide/Si interface depended on the diameter of the Si nanowires, such that epitaxial NiSi2 with a {111} facet was formed at the Ni-silicide/Si interface in Si nanowires with large diameter, and NiSi was formed in Si nanowires with small diameter. A mechanism that is based on flux divergence and a nucleation-limited reaction is proposed to explain this phenomenon of size-dependent phase formation. PMID:23663726

  17. Formation of Mg silicides on amorphous Si. Origin and role of high pressure in the film growth

    Energy Technology Data Exchange (ETDEWEB)

    Dotsenko, S.A. [Institute for Automation and Control Processes, 5 Radio St., Vladivostok 690041 (Russian Federation); Far Eastern Federal University, Physics Dpt., 8 Sukhanova Str., Vladivostok 690950 (Russian Federation); Gouralnik, A.S., E-mail: [Institute for Automation and Control Processes, 5 Radio St., Vladivostok 690041 (Russian Federation); Galkin, N.G. [Institute for Automation and Control Processes, 5 Radio St., Vladivostok 690041 (Russian Federation); Far Eastern Federal University, Physics Dpt., 8 Sukhanova Str., Vladivostok 690950 (Russian Federation); Galkin, K.N. [Institute for Automation and Control Processes, 5 Radio St., Vladivostok 690041 (Russian Federation); Gutakovski, A.K.; Neklyudova, M.A. [Rzhanov Institute of Semiconductor Physics, Siberian Branch Russian Academy of Sciences, Lavrentiev Av., Novosibirsk (Russian Federation)


    Growth of Mg film on amorphous Si (a-Si) at room temperature in UHV conditions was studied in situ with optical differential reflection spectroscopy and electron energy loss spectroscopy. The phase composition of the film was also studied by high-resolution transmission electron microscopy. The mechanism of silicide film growth on a-Si is considered. The origin of internal stress within the growing film and its role in the silicide film growth process are discussed. Due to high pressure occurring within the growing film, the first phase to form is the hexagonal silicide phase h-Mg{sub 2}Si. According to the DRS data, the phase h-Mg{sub 2}Si is semiconducting. The new peak in the differential reflectance spectrum is assigned to the h-Mg{sub 2}Si. At later stages of Mg deposition the cubic silicide phase c-Mg{sub 2}Si grows. - Highlights: • The film growth by UHV deposition of Mg on amorphous Si layer was studied. • Two Mg{sub 2}Si phases, hexagonal and cubic, were formed on amorphous Silicon. • The metastable h-Mg{sub 2}Si forms first, due to very high stress inside the film. • The stress is induced by chemical forces during intermixing of Mg with Si. • The film growth stages are clearly seen by Differential Reflectance Spectroscopy.

  18. Aluminium alloyed iron-silicide/silicon solar cells: A simple approach for low cost environmental-friendly photovoltaic technology. (United States)

    Kumar Dalapati, Goutam; Masudy-Panah, Saeid; Kumar, Avishek; Cheh Tan, Cheng; Ru Tan, Hui; Chi, Dongzhi


    This work demonstrates the fabrication of silicide/silicon based solar cell towards the development of low cost and environmental friendly photovoltaic technology. A heterostructure solar cells using metallic alpha phase (α-phase) aluminum alloyed iron silicide (FeSi(Al)) on n-type silicon is fabricated with an efficiency of 0.8%. The fabricated device has an open circuit voltage and fill-factor of 240 mV and 60%, respectively. Performance of the device was improved by about 7 fold to 5.1% through the interface engineering. The α-phase FeSi(Al)/silicon solar cell devices have promising photovoltaic characteristic with an open circuit voltage, short-circuit current and a fill factor (FF) of 425 mV, 18.5 mA/cm(2), and 64%, respectively. The significant improvement of α-phase FeSi(Al)/n-Si solar cells is due to the formation p(+-)n homojunction through the formation of re-grown crystalline silicon layer (~5-10 nm) at the silicide/silicon interface. Thickness of the regrown silicon layer is crucial for the silicide/silicon based photovoltaic devices. Performance of the α-FeSi(Al)/n-Si solar cells significantly depends on the thickness of α-FeSi(Al) layer and process temperature during the device fabrication. This study will open up new opportunities for the Si based photovoltaic technology using a simple, sustainable, and los cost method.

  19. Numerical simulation and experimental validation of liquid water behaviors in a proton exchange membrane fuel cell cathode with serpentine channels (United States)

    Le, Anh Dinh; Zhou, Biao; Shiu, Huan-Ruei; Lee, Chun-I.; Chang, Wen-Chen

    The volume-of-fluid (VOF) approach is one of the most promising methods of investigating water transport and water management in proton exchange membrane fuel cells (PEMFCs). A general PEMFC model combined with the VOF method has been developed by our group to simulate the mechanisms of fluid flows, mass and heat transport, and electrochemical reactions in a PEMFC, and it is necessary to validate the numerical model through experiments. In this paper, both the numerical model and an experimental visualization that can simulate the motion and transport behavior of liquid water in a cathode flow channel of a PEMFC are presented. Direct optical visualization is used in this work to capture the droplets' motions with high spatial and temporal resolutions. The numerical model and experimental setup have similar geometric dimensions and operating conditions, and the results of the experiment are in good agreement with numerical simulations. Moreover, the physics of droplet and liquid water behavior based on certain material and liquid properties and the operating conditions in the fuel cell channel are also addressed. This analysis also offers some basic understanding of the mechanism of liquid droplet dynamics in numerical and experimental studies of micro-fluidics.

  20. Fuel Surrogate Physical Property Effects on Direct Injection Spray and Ignition Behavior (United States)


    the injected fuel parcels [22]. Liquid droplet collision and coalescence was modeled with the No Time Counter collision model [24] in conjunction...within the spray were modeled with the Lagrangian- Droplet and Eulerian-Fluid approach. The Reynolds Averaged Navier Stokes (RANS) equations with... droplet were described with a number of phenomenological and physical models. The blob injection method of Reitz and Diwakar [23] was employed. The

  1. Modeling and simulation of hydrogen behavior in Zircaloy-4 fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Jason D. Hales; Various


    As a result of corrosion during normal operation in nuclear reactors, hydrogen can enter the zirconium-alloy fuel cladding and precipitate as brittle hydride platelets, which can severely degrade the cladding ductility. Under a heterogeneous temperature distribution, hydrides tend to accumulate in the colder areas, creating local spots of degraded cladding that can favor crack initiation. Therefore, an estimation of the local hydride distribution is necessary to help predict the risk of cladding failure. The hydride distribution is governed by three competing phenomena. Hydrogen in solid solution diffuses under a concentration gradient due to Fick’s law and under a temperature gradient due to the Soret effect. Precipitation of the hydride platelets occurs once the hydrogen solubility limit is reached. A model of these phenomena was implemented in the 3D fuel performance code BISON in order to calculate the hydrogen distribution for arbitrary geometries, such as a nuclear fuel rod, and is now available for BISON users. Simulations have been performed on simple geometries to validate the model and its implementation. The simulations predict that before precipitation occurs, hydrogen tends to accumulate in the colder spots due to the Soret effect. Once the solubility limit is reached, hydrogen precipitates and forms a rim close to the outer edge of the cladding. The simulations also predict that the reactor shut down has little effect on already precipitated hydrides but causes the remaining hydrogen to precipitate homogeneously into hydrides.

  2. Modeling and simulation of hydrogen behavior in Zircaloy-4 fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Courty, Olivier, E-mail: [Pennsylvania State University, 45 Bd Gouvion Saint Cyr, 75017 Paris (France); Motta, Arthur T., E-mail: [Department of Mechanical and Nuclear Engineering, 227 Reber Building, Penn State University, University Park, PA 16802 (United States); Hales, Jason D., E-mail: [Fuels Modeling and Simulation Department, Idaho National Laboratory (United States)


    As a result of corrosion during normal operation in nuclear reactors, hydrogen can enter the zirconium-alloy fuel cladding and precipitate as brittle hydride platelets, which can severely degrade the cladding ductility. Under a heterogeneous temperature distribution, hydrides tend to accumulate in the colder areas, creating local spots of degraded cladding that can favor crack initiation. Therefore, an estimation of the local hydride distribution is necessary to help predict the risk of cladding failure. The hydride distribution is governed by three competing phenomena. Hydrogen in solid solution diffuses under a concentration gradient due to Fick’s law and under a temperature gradient due to the Soret effect. Precipitation of the hydride platelets occurs once the hydrogen solubility limit is reached. A model of these phenomena was implemented in the 3D fuel performance code BISON in order to calculate the hydrogen distribution for arbitrary geometries, such as a nuclear fuel rod, and is now available for BISON users. Simulations have been performed on simple geometries to validate the model and its implementation. The simulations predict that before precipitation occurs, hydrogen tends to accumulate in the colder spots due to the Soret effect. Once the solubility limit is reached, hydrogen precipitates and forms a rim close to the outer edge of the cladding. The simulations also predict that the reactor shut down has little effect on already precipitated hydrides but causes the remaining hydrogen to precipitate homogeneously into hydrides.

  3. Free air breathing proton exchange membrane fuel cell: Thermal behavior characterization near freezing temperature (United States)

    Higuita Cano, Mauricio; Kelouwani, Sousso; Agbossou, Kodjo; Dubé, Yves


    A free air breathing fuel cell thermal model is developed. This proton exchange membrane fuel cell (PEMFC) has been selected as the basis for the study due to its use in automotive applications. The blowers integrated to the stack provide the required air flow for hydrogen oxidation as well as the fluid for the stack thermal regulation. Hence, their controls are a key point for keeping the system to maximum efficiency. Using well-known fuel cell electrochemistry, a dynamic thermal model near freezing temperature, which includes the stack physical parameters, is developed and validated. In addition to these parameters, only the inlet and outlet air temperatures are used to derive the model. Experimental validation with a real 1 kW free air breathing PEMFC has demonstrated that the model can reasonably track the stack internal temperature with a maximum deviation between the observed and the estimated temperatures of 5%. Therefore, the proposed method will allow the development of efficient blower management systems for PEMFC efficiency improvement.

  4. Ni-YSZ solid oxide fuel cell anode behavior upon redox cycling based on electrical characterization

    DEFF Research Database (Denmark)

    Klemensø, Trine; Mogensen, Mogens Bjerg


    Nickel (Ni)—yttria-stabilized zirconia (YSZ) cermets are a prevalent material used for solid oxide fuel cells. The cermet degrades upon redox cycling. The degradation is related to microstructural changes, but knowledge of the mechanisms has been limited. Direct current conductivity measurements...... were performed on cermets and cermets where the Ni component was removed. Measurements were carried out before, during, and after redox cycling the cermet. The cermet conductivity degraded over time due to sintering of the nickel phase. Following oxidizing events, the conductivity of the cermets...

  5. Fuel behavior in severe accidents and Mo-alloy based cladding designs to improve accident tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Bo [Electric Power Research Institute, Palo Alto, CA (United States). Nucler Power Sector


    The severe accidents at TMI-2 and Fukushima-Daiichi led to core meltdown and hydrogen explosions. The main source of energy causing core melting is the decay heat from {beta}-, {beta}+, and {gamma} decays of short-lived isotopes following a power scram. The exothermic reaction of Zr-alloy cladding can further increase the cladding temperature leading to rapid cladding corrosion and hydrogen production. The most effective mitigation to minimize core damage in a severe accident is to extend the duration of heat removal capacity via battery-supported passive cooling for as long as practically possible. Replacing the Zr-alloy cladding with a higher heat resistant cladding with lower enthalpy release rate may also provide additional coping time for accident management. Such a heat resistant cladding may also overcome the current licensing concerns about Zr-alloy hydriding and post quench ductility issues in a design base loss of coolant accident (LOCA). Zr-alloy cladding, while has been optimized for normal operation in high pressure water and steam of light water reactors, will rapidly lose its corrosion resistance and tensile and creep strength in high pressure steam. Evaluation of alternate cladding materials and designs have been performed to search for a new fuel cladding design which will substantially improve the safety margins at elevated temperatures during a severe accident, while maintaining the excellent fuel performance attributes of the current Zr-alloy cladding. The screening criteria for the evaluation include neutronic properties, material availability, adaptability and operability in current LWRs, resistance to melting. The new designs also need to be fabricable, maintain sufficient strength and resist to attack by high pressure steam. Engineering metals, alloys and ceramics which can meet some or most of these requirements are limited. Following review of the properties of potential candidates, it is concluded that molybdenum alloys may potentially

  6. A study of solid oxide fuel cell stack failure by inducing abnormal behavior in a single cell test (United States)

    Lim, Hyung-Tae; Virkar, Anil V.

    It is well known that cell imbalance can lead to failure of batteries. Prior theoretical modeling has shown that similar failure can occur in solid oxide fuel cell (SOFC) stacks due to cell imbalance. Central to failure model for SOFC stacks is the abnormal operation of a cell with cell voltage becoming negative. For investigation of SOFC stack failure by simulating abnormal behavior in a single cell test, thin yttria-stabilized zirconia (YSZ) electrolyte, anode-supported cells were tested at 800 °C with hydrogen as fuel and air as oxidant with and without an applied DC bias. When under a DC bias with cell operating under a negative voltage, rapid degradation occurred characterized by increased cell resistance. Visual and microscopic examination revealed that delamination occurred along the electrolyte/anode interface. The present results show that anode-supported SOFC stacks with YSZ electrolyte are prone to catastrophic failure due to internal pressure buildup, provided cell imbalance occurs. The present results also suggest that the greater the number of cells in an SOFC stack, the greater is the propensity to catastrophic failure.

  7. Behavior of an improved Zr fuel cladding with oxidation resistant coating under loss-of-coolant accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong Jun, E-mail:; Kim, Hyun Gil; Jung, Yang Il; Park, Jung Hwan; Yang, Jae Ho; Koo, Yang Hyun


    This study investigates protective coatings for improving the high temperature oxidation resistance of Zr fuel claddings for light water nuclear reactors. FeCrAl alloy and Cr layers were deposited onto Zr plates and tubes using cold spraying. For the FeCrAl/Zr system, a Mo layer was introduced between the FeCrAl coating and the Zr matrix to prevent inter-diffusion at high temperatures. Both the FeCrAl and Cr coatings improved the oxidation resistance compared to that of the uncoated Zr alloy when exposed to a steam environment at 1200 °C. The ballooning behavior and mechanical properties of the coated cladding samples were studied under simulated loss-of-coolant accident conditions. The coated samples showed higher burst temperatures, lower circumferential strain, and smaller rupture openings compared to the uncoated Zr. Although 4-point bend tests of the coated samples showed a small increase in the maximum load, ring compression tests of a sectioned sample showed increased ductility. - Highlights: • Cr and FeCrAl were coated onto Zr fuel cladding for light water nuclear reactors. • Mo layer between FeCrAl and Zr prevented inter-diffusion at high temperatures. • Coated claddings were tested under loss-of-cooling accident conditions. • Coating improved high-temperature oxidation resistance and mechanical properties.

  8. Chemical vapour deposition of tungsten and tungsten silicide layers for applications in novel silicon technology

    CERN Document Server

    Li, F X


    This work was a detailed investigation into the Chemical Vapour Deposition (CVD) of tungsten and tungsten silicide for potential applications in integrated circuit (IC) and other microelectronic devices. These materials may find novel applications in contact schemes for transistors in advanced ICs, buried high conductivity layers in novel Silicon-On-Insulator (SOI) technology and in power electronic devices. The CVD techniques developed may also be used for metal coating of recessed or enclosed features which may occur in novel electronic or electromechanical devices. CVD of tungsten was investigated using the silicon reduction reaction of WF sub 6. W layers with an optimum self-limiting thickness of 100 nm and resistivity 20 mu OMEGA centre dot cm were produced self-aligned to silicon. A hydrogen passivation technique was developed as part of the wafer pre-clean schedule and proved essential in achieving optimum layer thickness. Layers produced by this approach are ideal for intimate contact to shallow junct...

  9. Friction and wear of radiofrequency-sputtered borides, silicides, and carbides (United States)

    Brainard, W. A.; Wheeler, D. R.


    The friction and wear properties of several refractory compound coatings were examined. These compounds were applied to 440 C bearing steel surfaces by radiofrequency (RF) sputtering. The refractory compounds were the titanium and molybdenum borides, the titanium and molybdenum silicides, and the titanium, molybdenum, and boron carbides. Friction testing was done with a pin-on-disk wear apparatus at loads from 0.1 to 5.0 newtons. Generally, the best wear properties were obtained when the coatings were bias sputtered onto 440 C disks that had been preoxidized. Adherence was improved because of the better bonding of the coatings to the iron oxide formed during preoxidation. As a class the carbides provided wear protection to the highest loads. Titanium boride coatings provided low friction and good wear properties to moderate loads.

  10. Analysis of self-oscillating behaviors aimed at the development of a molecular robot with organic acids as fuel (United States)

    Nakazumi, Tomoka; Hara, Yusuke


    We studied the transmittance self-oscillation of a polymer chain driven by an organic acid as the fuel. The self-oscillating polymer chain consists of 4-acryloylmorpholine (ACMO) and the Ru catalyst (Ru(bpy)3) of the Belousov–Zhabotinsky (BZ) reaction. The transmittance self-oscillating behavior was affected significantly by the temperature. As the amplitude of the transmittance self-oscillation, which is reflected by the aggregation state, decreased with time, the oscillation period also decreased. This trend indicates that the polymer aggregation affects the rate of the BZ reaction significantly. The activation energy of the self-oscillating value was almost the same in the normal BZ reaction, which does not include Ru(bpy)3 complexes in the polymer chains. In addition, we demonstrated the effect of one BZ substrate (sodium bromate or malonic acid) on the transmittance self-oscillation period.

  11. Discovery of Brownleeite: a New Manganese Silicide Mineral in an Interplanetary Dust Particle (United States)

    Keller, Lindsay P.; Nakamura-Messenger, Keiko; Clemett, Simon J.; Messenger, Scott; Jones, John H.; Palma, Russell L.; Pepin, Robert O.; Klock, Wolfgang; Zolensky, Michael E.; Tatsuoka, Hirokazu


    The Earth accretes approximately 40,000 tons of cosmic dust annually, originating mainly from the disintegration of comets and collisions among asteroids. This cosmic dust, also known as interplanetary dust particles (IDPs), is a subject of intense interest since it is made of the original building blocks of our Solar System. Although the specific parent bodies of IDPs are unknown, the anhydrous chondritic-porous IDPs (CP-IDPs) subset has been potentially linked to a cometary source. The CP-IDPs are extremely primitive materials based on their unequilibrated mineralogy, C-rich chemistry, and anomalous isotopic signatures. In particular, some CP-IDPs escaped the thermal, aqueous and impact shock processing that has modified or destroyed the original mineralogy of meteorites. Thus, the CP-IDPs represent some of the most primitive solar system materials available for laboratory study. Most CP-IDPs are comprised of minerals that are common on Earth. However, in the course of an examination of one of the CP-IDPs, we encountered three sub-micrometer sized grains of manganese silicide (MnSi), a phase that has heretofore not been found in nature. In the seminar, we would like to focus on IDP studies and this manganese silicide phase that has been approved as the first new mineral identified from a comet by the International Mineralogical Association (IMA) in 2008. The mineral is named in honour of Donald E. Brownlee, an American astronomer and a founder of the field of cosmic dust research who is the principal investigator of the NASA Stardust Mission that collected dust samples from Comet 81P/Wild-2 and returned them to Earth. Much of our current view and understanding of the early solar system would not exist without the pioneering work of professor Don Brownlee in the study of IDPs.

  12. Characterisation of amorphous molybdenum silicide (MoSi) superconducting thin films and nanowires (United States)

    Banerjee, Archan; Baker, Luke J.; Doye, Alastair; Nord, Magnus; Heath, Robert M.; Erotokritou, Kleanthis; Bosworth, David; Barber, Zoe H.; MacLaren, Ian; Hadfield, Robert H.


    We report on the optimisation of amorphous molybdenum silicide thin film growth for superconducting nanowire single-photon detector (SNSPD) applications. Molybdenum silicide was deposited via co-sputtering from Mo and Si targets in an Ar atmosphere. The superconducting transition temperature (T c) and sheet resistance (R s) were measured as a function of thickness and compared to several theoretical models for disordered superconducting films. Superconducting and optical properties of amorphous materials are very sensitive to short- (up to 1 nm) and medium-range order (˜1-3 nm) in the atomic structure. Fluctuation electron microscopy studies showed that the films assumed an A15-like medium-range order. Electron energy loss spectroscopy indicates that the film stoichiometry was close to Mo83Si17, which is consistent with reports that many other A15 structures with the nominal formula A 3 B show a significant non-stoichiometry with A:B > 3:1. Optical properties from ultraviolet (270 nm) to infrared (2200 nm) wavelengths were measured via spectroscopic ellipsometry for 5 nm thick MoSi films indicating high long wavelength absorption. We also measured the current density as a function of temperature for nanowires patterned from a 10 nm thick MoSi film. The current density at 3.6 K is 3.6 × 105 A cm-2 for the widest wire studied (2003 nm), falling to 2 × 105 A cm-2 for the narrowest (173 nm). This investigation confirms the excellent suitability of MoSi for SNSPD applications and gives fresh insight into the properties of the underlying materials.

  13. The R&D PERFROI Project on Thermal Mechanical and Thermal Hydraulics Behaviors of a Fuel Rod Assembly during a Loss of Coolant Accident

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, G. [Institut de Radioprotection et de Surete Nucleaire, Cadarache (France); Dominguez, C. [Institut de Radioprotection et de Surete Nucleaire, Cadarache (France); Durville, B. [Institut de Radioprotection et de Surete Nucleaire, Cadarache (France); Carnemolla, S. [Institut de Radioprotection et de Surete Nucleaire, Cadarache (France); Campello, D. [Institut National des Sciences Appliques, Lyon (France); Tardiff, N. [Institut National des Sciences Appliques, Lyon (France); Gradeck, M. [Univ. de Lorraine, Nancy, France. LEMTA


    The safety principle in case of a LOCA is to preserve the short and long term coolability of the core. The associated safety requirements are to ensure the resistance of the fuel rods upon quench and post-quench loads and to maintain a coolable geometry in the core. An R&D program has been launched by IRSN with the support of EDF, to perform both experimental and modeling activities in the frame of the LOCA transient, on technical issues such as: - flow blockage within a fuel rods bundle and its potential impact on coolability, - fuel fragment relocation in the ballooned areas: its potential impact on cladding PCT (Peak Cladding Temperature) and on the maximum oxidation rate, - potential loss of cladding integrity upon quench and post-quench loads. The PERFROI project (2014-2019) focusing on the first above issue, is structured in two axes: 1. axis 1: thermal mechanical behavior of deformation and rupture of cladding taking into account the contact between fuel rods; specific research at LaMCoS laboratory focus on the hydrogen behavior in cladding alloys and its impact on the mechanical behavior of the rod; and, 2. axis 2: thermal hydraulics study of a partially blocked region of the core (ballooned area taking into account the fuel relocation with local over power), during cooling phase by water injection; More detailed activities foreseen in collaboration with LEMTA laboratory will focus on the characterization of two phase flows with heat transfer in deformed structures.

  14. Oxidation behavior of metallic interconnect in solid oxide fuel cell stack (United States)

    Li, Jun; Zhang, Wenying; Yang, Jiajun; Yan, Dong; Pu, Jian; Chi, Bo; Jian, Li


    Oxidation behavior of integrated interconnect with bipolar plate and corrugated sheet made by ferrite steel SUS430 is investigated and compared in simulated environment and in a realistic stack. Electrical current is found to have a direction-related impact on the thickness of the Cr2O3/MnCr2O4 composite oxide scale. Oxide scale of the interconnect aged in the stack exhibits a dual-layered structure of a complex Mn-Cr oxide layer covered by iron oxide. The oxidation rates vary greatly depending on its local environment, with different thermal, electrical density, as well as gas composition conditions. By analyzing the thickness distribution of oxide scale and comparing them with the simulated test result, the oxidation behavior of interconnect in stack is described in high definition. ASR distribution is also conducted by calculation, which could help further understanding the behavior of stack degradation.



  16. Comparison of the Thermal Expansion Behavior of Several Intermetallic Silicide Alloys Between 293 and 1523 K (United States)

    Raj, S. V.


    Thermal expansion measurements were conducted on hot-pressed CrSi2, TiSi2, WSi2 and a two-phase Cr-Mo-Si intermetallic alloy between 303 and 1523 K during three heat-cool cycles. The corrected thermal expansion, (Δ L/ L 0)thermal, varied with the absolute temperature, T, as where, A, B, C, and D are regression constants. Excellent reproducibility was observed for most of the materials after the first heat-up cycle. In some cases, the data from first heat-up cycle deviated from those determined in the subsequent cycles. This deviation was attributed to the presence of residual stresses developed during processing, which are relieved after the first heat-up cycle.

  17. BEHAVE: fire behavior prediction and fuel modeling system - BURN subsystem, Part 2 (United States)

    Patricia L. Andrews; Carolyn H. Chase


    This is the third publication describing the BEHAVE system of computer programs for predicting behavior of wildland fires. This publication adds the following predictive capabilities: distance firebrands are lofted ahead of a wind-driven surface fire, probabilities of firebrands igniting spot fires, scorch height of trees, and percentage of tree mortality. The system...

  18. Fuel flexible fuel injector (United States)

    Tuthill, Richard S; Davis, Dustin W; Dai, Zhongtao


    A disclosed fuel injector provides mixing of fuel with airflow by surrounding a swirled fuel flow with first and second swirled airflows that ensures mixing prior to or upon entering the combustion chamber. Fuel tubes produce a central fuel flow along with a central airflow through a plurality of openings to generate the high velocity fuel/air mixture along the axis of the fuel injector in addition to the swirled fuel/air mixture.

  19. Ceria based inverse opals for thermochemical fuel production: Quantification and prediction of high temperature behavior (United States)

    Casillas, Danielle Courtney

    Solar energy has the potential to supply more than enough energy to meet humanity's energy demands. Here, a method for thermochemical solar energy storage through fuel production is presented. A porous non-stoichiometric oxide, ceria, undergoes partial thermal reduction and oxidation with concentrated solar energy as a heat source, and water as an oxidant. The resulting yields for hydrogen fuel and oxygen are produced in two discrete steps, while the starting material maintains its original phase. Ordered porosity has been shown superior to random porosity for thermochemical fuel production applications, but stability limits for these structures are currently undefined. Ceria-based inverse opals are currently being investigated to assess the architectural influence on thermochemical hydrogen production. Low tortuosity and continuous interconnected pore network allow for facile gas transport and improved reaction kinetics. Ceria-based ordered materials have recently been shown to increase maximum hydrogen production over non-ordered porous ceria. Thermal stability of ordered porosity was quantified using quantitative image analysis. Fourier analysis was applied to SEM images of the material. The algorithm results in an order parameter gamma that describes the degree of long range order maintained by these structures, where gamma>4 signifies ordered porosity. According to this metric, a minimum zirconium content of 20 atomic percent (at%) is necessary for these architectures to survive aggressive annealing up to 1000°C. Zirconium substituted ceria (ZSC) with Zr loadings in excess of 20at% developed undesired tetragonal phases. Through gamma, we were able to find a balance between the benefit of zirconium additions on structural stability and its negative impact on phase. This work demonstrates the stability of seemingly delicate architectures, and the operational limit for ceria based inverse opals to be 1000°C for 1microm pore size. Inverse opals having sub

  20. Electronic structures of platinum group elements silicides calculated by a first-principle pseudopotential method using plane-wave basis

    Energy Technology Data Exchange (ETDEWEB)

    Imai, Y. [National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 5, Higashi 1-1 Tsukuba, Ibaraki 305-8565 (Japan); Watanabe, A. [National Institute of Advanced Industrial Science and Technology, AIST Tsukuba Central 5, Higashi 1-1 Tsukuba, Ibaraki 305-8565 (Japan)


    The electronic structures of platinum group elements (Ru, Os, Rh, Ir, Pd, and Pt) silicides have been calculated. Ir{sub 3}Si{sub 5} is a semiconductor with the direct gap of 1.14 eV. Among monosilicides, RuSi and OsSi with the FeSi-type structure are semiconductors with the gap values of 0.21 and 0.41 eV but RhSi, IrSi, PdSi, and PtSi with the MnP-type structure are metals. No semiconducting compounds can be found in other platinum group elements silicides other than known Ru{sub 2}Si{sub 3}, Os{sub 2}Si{sub 3}, and OsSi{sub 2}.

  1. Fabrication and microstructural analysis of UN-U{sub 3}Si{sub 2} composites for accident tolerant fuel applications

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kyle D., E-mail:; Raftery, Alicia M.; Lopes, Denise Adorno; Wallenius, Janne


    In this study, U{sub 3}Si{sub 2} was synthesized via the use of arc-melting and mixed with UN powders, which together were sintered using the SPS method. The study revealed a number of interesting conclusions regarding the stability of the system – namely the formation of a probable but as yet unidentified ternary phase coupled with the reduction of the stoichiometry in the nitride phase – as well as some insights into the mechanics of the sintering process itself. By milling the silicide powders and reducing its particle size ratio compared to UN, it was possible to form a high density UN-U{sub 3}Si{sub 2} composite, with desirable microstructural characteristics for accident tolerant fuel applications. - Highlights: • U{sub 3}Si{sub 2} fabricated from elemental uranium and silicon through arc melting. • Homogeneity of the silicides assessed through densitometry, XRD, SEM and EDS, chemical etching and optical microscopy. • UN powder fabricated using hydriding-nitriding method. • No phase transformations detected when sintering using silicide particle sizes less than UN particle size. • High density composite (98%TD) fabricated with silicide grain coating using spark plasma sintering at 1450 °C.

  2. Aluminium alloyed iron-silicide/silicon solar cells: A simple approach for low cost environmental-friendly photovoltaic technology (United States)

    Kumar Dalapati, Goutam; Masudy-Panah, Saeid; Kumar, Avishek; Cheh Tan, Cheng; Ru Tan, Hui; Chi, Dongzhi


    This work demonstrates the fabrication of silicide/silicon based solar cell towards the development of low cost and environmental friendly photovoltaic technology. A heterostructure solar cells using metallic alpha phase (α-phase) aluminum alloyed iron silicide (FeSi(Al)) on n-type silicon is fabricated with an efficiency of 0.8%. The fabricated device has an open circuit voltage and fill-factor of 240 mV and 60%, respectively. Performance of the device was improved by about 7 fold to 5.1% through the interface engineering. The α-phase FeSi(Al)/silicon solar cell devices have promising photovoltaic characteristic with an open circuit voltage, short-circuit current and a fill factor (FF) of 425 mV, 18.5 mA/cm2, and 64%, respectively. The significant improvement of α-phase FeSi(Al)/n-Si solar cells is due to the formation p+−n homojunction through the formation of re-grown crystalline silicon layer (~5–10 nm) at the silicide/silicon interface. Thickness of the regrown silicon layer is crucial for the silicide/silicon based photovoltaic devices. Performance of the α-FeSi(Al)/n-Si solar cells significantly depends on the thickness of α-FeSi(Al) layer and process temperature during the device fabrication. This study will open up new opportunities for the Si based photovoltaic technology using a simple, sustainable, and los cost method. PMID:26632759

  3. Evaluation of powder metallurgical processing routes for multi-component niobium silicide-based high-temperature alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seemueller, Hans Christoph Maximilian


    Niobium silicide-based composites are potential candidates to replace nickel-base superalloys for turbine applications. The goal of this work was to evaluate the feasibility and differences in ensuing properties of various powder metallurgical processing techniques that are capable of manufacturing net-shape turbine components. Two routes for powder production, mechanical alloying and gas atomization were combined with compaction via hot isostatic pressing and powder injection molding.

  4. Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells (United States)

    Brahmi, Hatem; Ravipati, Srikanth; Yarali, Milad; Shervin, Shahab; Wang, Weijie; Ryou, Jae-Hyun; Mavrokefalos, Anastassios


    Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400-600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3-6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude-Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ~0.15 µΩ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor.

  5. Modeling defect and fission gas properties in U-Si fuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Christopher Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Noordhoek, Mark [Univ. of South Carolina, Columbia, SC (United States); Besmann, Theodore [Univ. of South Carolina, Columbia, SC (United States); Middleburgh, Simon C. [Westinghouse Electric Sweden, Vasteras (Sweden); Lahoda, E. J. [Westinghouse Electric Company LLC, Cranberry Woods, PA (United States); Chernatynskiy, Aleksandr [Missouri University of Science and Technology; Grimes, Robin W. [Imperial College, London (United Kingdom)


    Uranium silicides, in particular U3Si2, are being explored as an advanced nuclear fuel with increased accident tolerance as well as competitive economics compared to the baseline UO2 fuel. They benefit from high thermal conductivity (metallic) compared to UO2 fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for USi fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap.

  6. Modeling defect and fission gas properties in U-Si fuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Christopher Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Noordhoek, Mark J. [Univ. of South Carolina, Columbia, SC (United States); Besmann, Theodore M. [Univ. of South Carolina, Columbia, SC (United States); Middleburgh, Simon C. [Westinghouse Electric Sweden, Vasteras (Sweden); Lahoda, E. J. [Westinghouse Electric Company LLC, Cranberry Woods, PA (United States); Chernatynskiy, Aleksandr [Missouri Univ. of Science and Technology, Rolla, MO (United States); Grimes, Robin W. [Imperial College, London (United Kingdom)


    Uranium silicides, in particular U3Si2, are being explored as an advanced nuclear fuel with increased accident tolerance as well as competitive economics compared to the baseline UO2 fuel. They benefit from high thermal conductivity (metallic) compared to UO2 fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for USi fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap.

  7. Bio-derived Fuel Blend Dilution of Marine Engine Oil and Imapct on Friction and Wear Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Ajayi, Oyelayo O.; Lorenzo-Martin, Cinta; Fenske, George R.; Corlett, John; Murphy, Chris; Przesmitzki, Steve


    To reduce the amount of petroleum-derived fuel used in vehicles and vessels powered by internal combustion engines, the addition of bio-derived fuel extenders is a common practice. Ethanol is perhaps the most common bio-derived fuel used for blending, and butanol is being evaluated as a promising alternative. The present study determined the fuel dilution rate of three lubricating oils (E0, E10, and i-B16) in a marine engine operating in on-water conditions with a start-and-stop cycle protocol. The level of fuel dilution increased with the number of cycles for all three fuels. The most dilution was observed with i-B16 fuel, and the least with E10 fuel. In all cases, fuel dilution substantially reduced the oil viscosity. The impacts of fuel dilution and the consequent viscosity reduction on the lubricating capability of the engine oil in terms of friction, wear, and scuffing prevention were evaluated by four different tests protocols. Although the fuel dilution of the engine oil had minimal effect on friction, because the test conditions were under the boundary lubrication regime, significant effects were observed on wear in many cases. Fuel dilution also was observed to reduce the load-carrying capacity of the engine oils in terms of scuffing load reduction.

  8. Effects of fuel particle size and fission-fragment-enhanced irradiation creep on the in-pile behavior in CERCER composite pellets

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yunmei [Institute of Mechanics and Computational Engineering, Department of Aeronautics and Astronautics, Fudan University, Shanghai 200433 (China); Ding, Shurong, E-mail: [Institute of Mechanics and Computational Engineering, Department of Aeronautics and Astronautics, Fudan University, Shanghai 200433 (China); Zhang, Xunchao; Wang, Canglong; Yang, Lei [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)


    The micro-scale finite element models for CERCER pellets with different-sized fuel particles are developed. With consideration of a grain-scale mechanistic irradiation swelling model in the fuel particles and the irradiation creep in the matrix, numerical simulations are performed to explore the effects of the particle size and the fission-fragment-enhanced irradiation creep on the thermo-mechanical behavior of CERCER pellets. The enhanced irradiation creep effect is applied in the 10 μm-thick fission fragment damage matrix layer surrounding the fuel particles. The obtained results indicate that (1) lower maximum temperature occurs in the cases with smaller-sized particles, and the effects of particle size on the mechanical behavior in pellets are intricate; (2) the first principal stress and radial axial stress remain compressive in the fission fragment damage layer at higher burnup, thus the mechanism of radial cracking found in the experiment can be better explained. - Highlights: • A grain-scale gas swelling model considering the development of recrystallization and resolution is adopted for particles. • The influence of fission-gas-induced porosity is considered in the constitutive relations for particles. • A simulation method is developed for the multi-scale thermo-mechanical behavior. • The effects of fuel particle size and fission-fragment-enhanced irradiation creep are investigated in pellets.

  9. Neutron cross section sensitivity and uncertainty analysis of candidate accident tolerant fuel concepts

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Nicholas [Pennsylvania State University, University Park; Burns, Joseph R. [ORNL


    The aftermath of the Tōhoku earthquake and the Fukushima accident has led to a global push to improve the safety of existing light water reactors. A key component of this initiative is the development of nuclear fuel and cladding materials with potentially enhanced accident tolerance, also known as accident-tolerant fuels (ATF). These materials are intended to improve core fuel and cladding integrity under beyond design basis accident conditions while maintaining or enhancing reactor performance and safety characteristics during normal operation. To complement research that has already been carried out to characterize ATF neutronics, the present study provides an initial investigation of the sensitivity and uncertainty of ATF systems responses to nuclear cross section data. ATF concepts incorporate novel materials, including SiC and FeCrAl cladding and high density uranium silicide composite fuels, in turn introducing new cross section sensitivities and uncertainties which may behave differently from traditional fuel and cladding materials. In this paper, we conducted sensitivity and uncertainty analysis using the TSUNAMI-2D sequence of SCALE with infinite lattice models of ATF assemblies. Of all the ATF materials considered, it is found that radiative capture in 56Fe in FeCrAl cladding is the most significant contributor to eigenvalue uncertainty. 56Fe yields significant potential eigenvalue uncertainty associated with its radiative capture cross section; this is by far the largest ATF-specific uncertainty found in these cases, exceeding even those of uranium. We found that while significant new sensitivities indeed arise, the general sensitivity behavior of ATF assemblies does not markedly differ from traditional UO2/zirconium-based fuel/cladding systems, especially with regard to uncertainties associated with uranium. We assessed the similarity of the IPEN/MB-01 reactor benchmark model to application models with FeCrAl cladding. We used TSUNAMI-IP to calculate

  10. Transient Performance Behavior of Proton Exchange Membrane Fuel Cell by Configuration of Membrane and Gas Diffusion Layer (United States)

    Hwang, Sang Soon; Han, Sang Seok; Lee, Pil Hyong; Park, Bong Il

    A single-phase, fully three-dimensional transient numerical simulation was performed to analyze the dynamic response of a proton exchange membrane fuel cell (PEMFC) with single serpentine flow channels. . In addition, the effects of the membrane and gas diffusion layer thickness on current density transient behavior were investigated using numerical simulation. An overshoot of current density is observed for all thicknesses of the membrane and gas diffusion layer at an abrupt change of operating voltage from 0.7 V to 0.5 V. The peak of the overshoot and the elapsed thickness time to reach to the steady state value increase with decreasing membrane thickness. It is thought that the thin membrane facilitates the transport of water and ions through the membrane, resulting in an increase in current density and humidification of the membrane. The elapsed time to reach steady state voltage become shorter and the peak of the overshoot decreases as the thickness of the gas diffusion layer decreases. We suggest that this occurs because a thick gas diffusion layer increases the distance between the current collector (as heat exchanger) and catalyst layer (as heat source), resulting in a low transport rate of heat generated by the electrochemical reaction at the catalyst layer.

  11. A Transient Model for Fuel Cell Cathode-Water Propagation Behavior inside a Cathode after a Step Potential

    Directory of Open Access Journals (Sweden)

    Der-Sheng Chan


    Full Text Available Most of the voltage losses of proton exchange membrane fuel cells (PEMFC are due to the sluggish kinetics of oxygen reduction on the cathode and the low oxygen diffusion rate inside the flooded cathode. To simulate the transient flooding in the cathode of a PEMFC, a transient model was developed. This model includes the material conservation of oxygen, vapor, water inside the gas diffusion layer (GDL and micro-porous layer (MPL, and the electrode kinetics in the cathode catalyst layer (CL. The variation of hydrophobicity of each layer generated a wicking effect that moves water from one layer to the other. Since the GDL, MPL, and CL are made of composite materials with different hydrophilic and hydrophobic properties, a linear function of saturation was used to calculate the wetting contact angle of these composite materials. The balance among capillary force, gas/liquid pressure, and velocity of water in each layer was considered. Therefore, the dynamic behavior of PEMFC, with saturation transportation taken into account, was obtained in this study. A step change of the cell voltage was used to illustrate the transient phenomena of output current, water movement, and diffusion of oxygen and water vapor across the entire cathode.

  12. The effectiveness and limitations of fuel modeling using the fire and fuels extension to the Forest Vegetation Simulator (United States)

    Erin K. Noonan-Wright; Nicole M. Vaillant; Alicia L. Reiner


    Fuel treatment effectiveness is often evaluated with fire behavior modeling systems that use fuel models to generate fire behavior outputs. How surface fuels are assigned, either using one of the 53 stylized fuel models or developing custom fuel models, can affect predicted fire behavior. We collected surface and canopy fuels data before and 1, 2, 5, and 8 years after...

  13. Large-format platinum silicide microwave kinetic inductance detectors for optical to near-IR astronomy. (United States)

    Szypryt, P; Meeker, S R; Coiffard, G; Fruitwala, N; Bumble, B; Ulbricht, G; Walter, A B; Daal, M; Bockstiegel, C; Collura, G; Zobrist, N; Lipartito, I; Mazin, B A


    We have fabricated and characterized 10,000 and 20,440 pixel Microwave Kinetic Inductance Detector (MKID) arrays for the Dark-speckle Near-IR Energy-resolved Superconducting Spectrophotometer (DARKNESS) and the MKID Exoplanet Camera (MEC). These instruments are designed to sit behind adaptive optics systems with the goal of directly imaging exoplanets in a 800-1400 nm band. Previous large optical and near-IR MKID arrays were fabricated using substoichiometric titanium nitride (TiN) on a silicon substrate. These arrays, however, suffered from severe non-uniformities in the TiN critical temperature, causing resonances to shift away from their designed values and lowering usable detector yield. We have begun fabricating DARKNESS and MEC arrays using platinum silicide (PtSi) on sapphire instead of TiN. Not only do these arrays have much higher uniformity than the TiN arrays, resulting in higher pixel yields, they have demonstrated better spectral resolution than TiN MKIDs of similar design. PtSi MKIDs also do not display the hot pixel effects seen when illuminating TiN on silicon MKIDs with photons with wavelengths shorter than 1 µm.

  14. Formation of the Thermoelectric Candidate Chromium Silicide by Use of a Pack-Cementation Process (United States)

    Stathokostopoulos, D.; Chaliampalias, D.; Tarani, E.; Theodorakakos, A.; Giannoulatou, V.; Polymeris, G. S.; Pavlidou, E.; Chrissafis, K.; Hatzikraniotis, E.; Paraskevopoulos, K. M.; Vourlias, G.


    Transition-metal silicides are reported to be good candidates for thermoelectric applications because of their thermal and structural stability, high electrical conductivity, and generation of thermoelectric power at elevated temperatures. Chromium disilicide (CrSi2) is a narrow-gap semiconductor and a potential p-type thermoelectric material up to 973 K with a band gap of 0.30 eV. In this work, CrSi2 was formed from Si wafers by use of a two-step, pack-cementation, chemical diffusion method. Several deposition conditions were used to investigate the effect of temperature and donor concentration on the structure of the final products. Scanning electron microscopy and x-ray diffraction analysis were performed for phase identification, and thermal stability was evaluated by means of thermogravimetric measurements. The results showed that after the first step, chromizing, the structure of the products was a mixture of several Cr-Si phases, depending on the donor (Cr) concentration during the deposition process. After the second step, siliconizing, the pure CrSi2 phase was formed as a result of Si enrichment of the initial Cr-Si phases. It was also revealed that this compound has thermoelectric properties similar to those reported elsewhere. Moreover, it was found to have exceptional chemical stability even at temperatures up to 1273 K.

  15. XTEM Studies of Nickel Silicide Growth on Si(100) Using a Ni/Ti Bilayer System (United States)

    Falke, U.; Fenske, F.; Schulze, S.; Hietschold, M.


    Using a Ni/Ti bilayer system on Si(100) substrates we found a preferential growth of epitaxial NiSi2 at reaction temperatures of about 475 °C. This is attributed to the relatively slow Ni transport rate through the Ti layer, which acts as a diffusion rate limiting barrier. Annealing temperatures of 500 °C lead to the formation of mainly orthorhombic NiSi with a small fraction of NiSi2. The silicide phases grow with well defined orientations with respect to the underlying Si lattice for annealing temperatures up to 475 °C. An einem Ni/Ti-Zweischichtsystem auf Si(100)-Substraten fanden wir ein bevorzugtes Wachstum von epitaktischem NiSi2 bei Reaktionstemperaturen von 475 °C. Das wird auf die geringe Transportrate für Ni durch die Ti-Schicht, die als Barriere zur Begrenzung der Diffusionsrate dient, zurückgeführt. Temperaturen von 500 °C führen zur Bildung von hauptsächlich orthorhombischem NiSi und, in geringem Maß, von NiSi2. Bis zu Temperaturen von 475 °C wachsen die Silicidphasen mit definierten Orientierungen in Bezug auf das darunterliegende Si-Gitter.

  16. Mesoscale Evaluation of Titanium Silicide Monolayer as a Cathode Host Material in Lithium-Sulfur Batteries (United States)

    Liu, Zhixiao; Balbuena, Perla B.; Mukherjee, Partha P.


    Two-dimensional materials are competitive candidates as cathode materials in lithium-sulfur batteries for immobilizing soluble polysulfides and mitigating the shuttle effect. In this study, a mesoscale modeling approach, which combines first-principles simulation and kinetic Monte Carlo simulation, is employed to evaluate titanium silicide (Ti2Si and TiSi2) monolayers as potential host materials in lithium-sulfur batteries. It is found that the Ti2Si monolayer has much stronger affinities to Li2S x ( x = 1, 2, 4) molecules than does the TiSi2 monolayer. Also, Ti2Si can facilitate the dissociation of long-chain Li2S4 to LiS2. On the other hand, TiSi2 can only provide a weak chemical interaction for trapping soluble Li2S4. Therefore, the Ti2Si monolayer can be considered to be the next-generation cathode material for lithium-sulfur batteries. Nevertheless, the strong interaction between Ti2Si and Li2S also causes fast surface passivation. How to control the Li2S precipitation on Ti2Si should be answered by future studies.

  17. Crystal structure of the ternary silicide Gd2Re3Si5

    Directory of Open Access Journals (Sweden)

    Vitaliia Fedyna


    Full Text Available A single crystal of the title compound, the ternary silicide digadolinium trirhenium pentasilicide, Gd2Re3Si5, was isolated from an alloy of nominal composition Gd20Re30Si50 synthesized by arc melting and investigated by X-ray single-crystal diffraction. Its crystal structure belongs to the U2Mn3Si5 structure type. All atoms in the asymmetric lie on special positions. The Gd site has site symmetry m..; the two Mn atoms have site symmetries m.. and 2.22; the three Si atoms have site symmetries m.., ..2 and 4.. . The coordination polyhedra of the Gd atoms have 21 vertices, while those of the Re atoms are cubooctahedra and 13-vertex polyhedra. The Si atoms are arranged as tricapped trigonal prisms, bicapped square antiprisms, or 11-vertex polyhedra. The crystal structure of the title compound is also related to the structure types CaBe2Ge2 and W5Si3. It can be represented as a stacking of Gd-centred polyhedra of composition [GdSi9]. The Re atoms form infinite chains with an Re—Re distance of 2.78163 (5 Å and isolated squares with an Re—Re distance of 2.9683 (6 Å.

  18. The new ternary silicide ErCo{sub 3}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dzevenko, Mariya; Bigun, Inna [Ivan Franko National Univ., Lviv (Ukraine). Dept. of Analytical Chemistry


    The new ternary silicide ErCo{sub 3}Si{sub 2} adopts the ErRh{sub 3}Si{sub 2} structure type (space group Imma, Pearson code oI24, Z = 4, a = 6.950(1), b = 9.020(2), c = 5.230(1) A, R{sub 1} = 0.0565, wR{sub 2} = 0.0355, 253 F{sup 2} values, 23 variables). It is a deformation derivative of the CeCo{sub 3}B{sub 2} structure type. The coordination of the Er atom shows a normal 20-vertex polyhedron [Er(Si{sub 6}Co{sub 12}Er{sub 2})]. The two similar coordination polyhedra of Co are a distorted icosahedron [Co(Si{sub 4}Co{sub 4}Er{sub 4})], and a distorted icosahedron with one capped face [Co(Si{sub 4}Co{sub 5}Er{sub 4})]. The Si atom is surrounded by the polyhedron [Si(Co{sub 6}Si{sub 2}Er{sub 3})]. (orig.)

  19. Magnesium silicide nanoparticles as a deoxygenation agent for cancer starvation therapy (United States)

    Zhang, Chen; Ni, Dalong; Liu, Yanyan; Yao, Heliang; Bu, Wenbo; Shi, Jianlin


    A material that rapidly absorbs molecular oxygen (known as an oxygen scavenger or deoxygenation agent (DOA)) has various industrial applications, such as in food preservation, anticorrosion of metal and coal deoxidation. Given that oxygen is vital to cancer growth, to starve tumours through the consumption of intratumoral oxygen is a potentially useful strategy in fighting cancer. Here we show that an injectable polymer-modified magnesium silicide (Mg2Si) nanoparticle can act as a DOA by scavenging oxygen in tumours and form by-products that block tumour capillaries from being reoxygenated. The nanoparticles are prepared by a self-propagating high-temperature synthesis strategy. In the acidic tumour microenvironment, the Mg2Si releases silane, which efficiently reacts with both tissue-dissolved and haemoglobin-bound oxygen to form silicon oxide (SiO2) aggregates. This in situ formation of SiO2 blocks the tumour blood capillaries and prevents tumours from receiving new supplies of oxygen and nutrients.


    Energy Technology Data Exchange (ETDEWEB)

    Daniel, W. E.; Hansen, E. K.; Shehee, T. C.


    This report includes the literature review, hydrogen off-gas calculations, and hydrogen generation tests to determine that H-Canyon can safely dissolve the Sodium Reactor Experiment (SRE; thorium fuel), Ford Nuclear Reactor (FNR; aluminum alloy fuel), and Denmark Reactor (DR-3; silicide fuel, aluminum alloy fuel, and aluminum oxide fuel) assemblies in the L-Bundles with respect to the hydrogen levels in the projected peak off-gas rates. This is provided that the number of L-Bundles charged to the dissolver is controlled. Examination of SRE dissolution for potential issues has aided in predicting the optimal batching scenario. The calculations detailed in this report demonstrate that the FNR, SRE, and DR-3 used nuclear fuel (UNF) are bounded by MURR UNF and may be charged using the controls outlined for MURR dissolution in a prior report.

  1. Technology for manufacturing dispersion nuclear fuel at IPEN/CNEN-SP

    Energy Technology Data Exchange (ETDEWEB)

    Durazzo, Michelangelo; Souza, Jose Antonio Batista de; Carvalho, Elita Fontenele Urano de; Saliba-Silva, Adonis Marcelo; Riella, Humberto Gracher, E-mail: [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)


    IPEN/CNEN-SP has been working for increasing radioisotope production in order to supply the expanding demand for radiopharmaceutical medicines requested by the Brazilian welfare. To reach this objective, the IPEN's IEA-R1 research reactor power capacity has been continuously increased starting from 2 MW aiming to reach 5 MW. In addition, another research reactor with power substantially greater than that of the IEA-R1 will be constructed in Brazil, the Brazilian Multipurpose Reactor - RMB. Since 1988, IPEN has been manufacturing its own fuel element, initially based on U{sub 3}O{sub 8}-Al dispersion fuel plates with 2.3 g U/cm{sup 3}. To support the reactor power increase and the new research reactor, higher uranium density into the fuel had to be achieved for better irradiation flux and also to minimize the irradiated fuel elements to be stored. Uranium silicide was the first chosen option. The U-Mo alloy is considered for future use. This paper describes the results of this program and the current status of silicide fuel fabrication and qualification, as well as the status of U Mo-Al dispersion fuel development. (author)

  2. Analysis of Channel Stress Induced by NiPt-Silicide in Metal-Oxide-Semiconductor Field-Effect Transistor and Its Generation Mechanism (United States)

    Mizuo, Mariko; Yamaguchi, Tadashi; Kudo, Shuichi; Hirose, Yukinori; Kimura, Hiroshi; Tsuchimoto, Jun-ichi; Hattori, Nobuyoshi


    Channel stress induced by NiPt-silicide films in metal-oxide-semiconductor field-effect transistors (MOSFETs) was demonstrated using UV-Raman spectroscopy, and its generation mechanism was revealed. It was possible to accurately measure the channel stress with the Raman test structure. The channel stress depends on the source/drain doping type and the second silicide annealing method. In order to discuss the channel stress generation mechanism, NiPt-silicide microstructure analyses were performed using X-ray diffraction analysis and scanning transmission electron microscopy. The channel stress generation mechanism can be elucidated by the following two factors: the change in the NiSi lattice spacing, which depends on the annealing temperature, and the NiSi crystal orientation. The analyses of these factors are important for controlling channel stress in stress engineering for high-performance transistors.

  3. M5Si3(M=Ti, Nb, Mo) Based Transition-Metal Silicides for High Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhihong [Iowa State Univ., Ames, IA (United States)


    Transition metal silicides are being considered for future engine turbine components at temperatures up to 1600 C. Although significant improvement in high temperature strength, room temperature fracture toughness has been realized in the past decade, further improvement in oxidation resistance is needed. Oxidation mechanism of Ti5Si3-based alloys was investigated. Oxidation behavior of Ti5Si3-based alloy strongly depends on the atmosphere. Presence of Nitrogen alters the oxidation behavior of Ti5Si3 by nucleation and growth of nitride subscale. Ti5Si3.2and Ti5Si3C0.5 alloys exhibited an excellent oxidation resistance in nitrogen bearing atmosphere due to limited dissolution of nitrogen and increased Si/Ti activity ratio. MoSi2 coating developed by pack cementation to protect Mo-based Mo-Si-B composites was found to be effective up to 1500 C. Shifting coating composition to T1+T2+Mo3Si region showed the possibility to extend the coating lifetime above 1500 C by more than ten times via formation of slow growing Mo3Si or T2 interlayer without sacrificing the oxidation resistance of the coating. The phase equilibria in the Nb-rich portion of Nb-B system has been evaluated experimentally using metallographic analysis and differential thermal analyzer (DTA). It was shown that Nbss (solid solution) and NbB are the only two primary phases in the 0-40 at.% B composition range, and the eutectic reaction L {leftrightarrow} NbSS + NbB was determined to occur at 2104 ± 5 C by DTA.

  4. FRAPCON-2: A Computer Code for the Calculation of Steady State Thermal-Mechanical Behavior of Oxide Fuel Rods

    Energy Technology Data Exchange (ETDEWEB)

    Berna, G. A; Bohn, M. P.; Rausch, W. N.; Williford, R. E.; Lanning, D. D.


    FRAPCON-2 is a FORTRAN IV computer code that calculates the steady state response of light Mater reactor fuel rods during long-term burnup. The code calculates the temperature, pressure, deformation, and tai lure histories of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include (a) heat conduction through the fuel and cladding, (b) cladding elastic and plastic deformation, (c) fuel-cladding mechanical interaction, (d) fission gas release, (e} fuel rod internal gas pressure, (f) heat transfer between fuel and cladding, (g) cladding oxidation, and (h) heat transfer from cladding to coolant. The code contains necessary material properties, water properties, and heat transfer correlations. FRAPCON-2 is programmed for use on the CDC Cyber 175 and 176 computers. The FRAPCON-2 code Is designed to generate initial conditions for transient fuel rod analysis by either the FRAP-T6 computer code or the thermal-hydraulic code, RELAP4/MOD7 Version 2.

  5. Effect of particle aging on chemical characteristics, smoldering, and fire behavior in mixed-conifer masticated fuel (United States)

    Pamela G. Sikkink; Theresa B. Jain; James Reardon; Faith Ann Heinsch; Robert E. Keane; Bret Butler; L. Scott. Baggett


    Mastication is a silvicultural technique that grinds, shreds, or chops trees or shrubs into pieces and redistributes the biomass onto the forest floor to form a layer of woody debris. Unlike other fuel treatments that remove this biomass, masticated biomass often remains on site, which increases total fuel loading and causes concern over how the masticated particles...

  6. HTGR Fuel performance basis

    Energy Technology Data Exchange (ETDEWEB)

    Shamasundar, B.I.; Stansfield, O.M.; Jensen, D.D.


    The safety characteristics of the high-temperature gas-cooled reactor (HTGR) during normal and accident conditions are determined in part by HTGR fuel performance. During normal operation, less than 0.1% fuel failure occurs, primarily from defective particles. This low fuel failure fraction limits circulating activity to acceptable levels. During severe accidents, the radiological consequence is influenced by high-temperature fuel particle behavior. An empirical fuel failure model, supported by recent experimental data, is presented. The onset of significant fuel particle failure occurs at temperatures in excess of 1600/sup 0/C, and complete fuel failure occurs at 2660/sup 0/C. This indicates that the fuel is more retentive at higher temperatures than previously assumed. The more retentive nature of the fuel coupled with the high thermal capacitance of the core results in slow release of fission products from the core during severe accidents.

  7. Fuel safety research 1999

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    In April 1999, the Fuel Safety Research Laboratory was newly established as a result of reorganization of the Nuclear Safety Research Center, JAERI. The laboratory was organized by combining three laboratories, the Reactivity Accident Laboratory, the Fuel Reliability Laboratory, and a part of the Sever Accident Research Laboratory. Consequently, the Fuel Safety Research Laboratory is now in charge of all the fuel safety research in JAERI. Various types of experimental and analytical researches are conducted in the laboratory by using the unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and hot cells in JAERI. The laboratory consists of five research groups corresponding to each research fields. They are; (a) Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). (b) Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). (c) Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). (d) Research group of fuel behavior analysis (FEMAXI group). (e) Research group of FP release/transport behavior from irradiated fuel (VEGA group). This report summarizes the outline of research activities and major outcomes of the research executed in 1999 in the Fuel Safety Research Laboratory. (author)

  8. Physical properties of ternary silicide superconductors Li2XSi3 (X = Rh, Os): An ab initio study (United States)

    Alam, M. A.; Zilani, M. A. K.; Parvin, F.; Hadi, M. A.


    An ab initio method, based on the plane wave pseudopotential and the generalized gradient approximation (GGA), is performed to investigate the physical properties such as structural, elastic, electronic and bonding properties of newly synthesized Li2RhSi3 and predicted Li2OsSi3 ternary silicide superconductors for the first time. Both of these compounds are mechanically stable and are brittle in nature. They also have good machinability. Electronic band structures reveal that these compounds have metallic characteristics. They possess complex bonding nature (metallic, covalent and ionic). According to theoretical Vickers hardness, Li2RhSi3 is softer than Li2OsSi3.

  9. Development of silicide coating over molybdenum based refractory alloy and its characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, S.P., E-mail: [Materials Processing Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Banerjee, S.; Sharma, I.G.; Suri, A.K. [Materials Processing Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)


    Molybdenum based refractory alloys are potential candidate materials for structural applications in high temperature compact nuclear reactors and fusion reactors. However, these alloys being highly susceptible to oxidation in air or oxygen at elevated temperature, undergoes severe losses from highly volatile molybdenum trioxide species. Present investigation, therefore, examines the feasibility of development of silicide type of coating over molybdenum base TZM alloy shape (Mo > 99 wt.%) using pack cementation coating technique. TZM alloy was synthesized in this laboratory from oxide intermediates of MoO{sub 2}, TiO{sub 2} and ZrO{sub 2} in presence of requisite amount of carbon, by alumino-thermic reduction smelting technique. The arc melted and homogenized samples of TZM alloy substrate was then embedded in the chosen and intimately mixed pack composition consisting of inert matrix (Al{sub 2}O{sub 3}), coating powder (Si) and activator (NH{sub 4}Cl) taken in the judicious proportion. The sealed charge packs contained in an alumina crucible were heated at temperatures of 1000 {sup o}C for 8-16 h heating cycle to develop the coating. The coating phase was confirmed to be of made of MoSi{sub 2} by XRD analysis. The morphology of the coating was studied by SEM characterization. It had revealed that the coating was diffusion bonded where Si from coating diffused inward and Mo from TZM substrate diffused outward to form the coating. The coating was found to be resistant to oxidation when tested in air up to 1200 {sup o}C. A maximum 100 {mu}m of coating thickness was achieved on each side of the substrate.

  10. Nuclear fuel elements design, fabrication and performance

    CERN Document Server

    Frost, Brian R T


    Nuclear Fuel Elements: Design, Fabrication and Performance is concerned with the design, fabrication, and performance of nuclear fuel elements, with emphasis on fast reactor fuel elements. Topics range from fuel types and the irradiation behavior of fuels to cladding and duct materials, fuel element design and modeling, fuel element performance testing and qualification, and the performance of water reactor fuels. Fast reactor fuel elements, research and test reactor fuel elements, and unconventional fuel elements are also covered. This volume consists of 12 chapters and begins with an overvie

  11. Experimental data regarding the characterization of the flame behavior near lean blowout in a non-premixed liquid fuel burner

    Directory of Open Access Journals (Sweden)

    Maria Grazia De Giorgi


    The data are related to the research article “Image processing for the characterization of flame stability in a non-premixed liquid fuel burner near lean blowout” in Aerospace Science and Technology [1].

  12. A Transient Model for Fuel Cell Cathode-Water Propagation Behavior inside a Cathode after a Step Potential

    National Research Council Canada - National Science Library

    Der-Sheng Chan; Kan-Lin Hsueh


      Most of the voltage losses of proton exchange membrane fuel cells (PEMFC) are due to the sluggish kinetics of oxygen reduction on the cathode and the low oxygen diffusion rate inside the flooded cathode...

  13. Preliminary Investigation of Candidate Materials for Use in Accident Resistant Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jason M. Harp; Paul A. Lessing; Blair H. Park; Jakeob Maupin


    As part of a Collaborative Research and Development Agreement (CRADA) with industry, Idaho National Laboratory (INL) is investigating several options for accident resistant uranium compounds including silicides, and nitrides for use in future light water reactor (LWR) fuels. This work is part of a larger effort to create accident tolerant fuel forms where changes to the fuel pellets, cladding, and cladding treatment are considered. The goal fuel form should have a resistance to water corrosion comparable to UO2, have an equal to or larger thermal conductivity than uranium dioxide, a melting temperature that allows the material to stay solid under power reactor conditions, and a uranium loading that maintains or improves current LWR power densities. During the course of this research, fuel fabricated at INL will be characterized, irradiated at the INL Advanced Test Reactor, and examined after irradiation at INL facilities to help inform industrial partners on candidate technologies.

  14. Fuel safety research 2001

    Energy Technology Data Exchange (ETDEWEB)

    Uetsuka, Hiroshi (ed.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    The Fuel Safety Research Laboratory is in charge of research activity which covers almost research items related to fuel safety of water reactor in JAERI. Various types of experimental and analytical researches are being conducted by using some unique facilities such as the Nuclear Safety Research Reactor (NSRR), the Japan Material Testing Reactor (JMTR), the Japan Research Reactor 3 (JRR-3) and the Reactor Fuel Examination Facility (RFEF) of JAERI. The research to confirm the safety of high burn-up fuel and MOX fuel under accident conditions is the most important item among them. The laboratory consists of following five research groups corresponding to each research fields; Research group of fuel behavior under the reactivity initiated accident conditions (RIA group). Research group of fuel behavior under the loss-of-coolant accident conditions (LOCA group). Research group of fuel behavior under the normal operation conditions (JMTR/BOCA group). Research group of fuel behavior analysis (FEMAXI group). Research group of radionuclides release and transport behavior from irradiated fuel under severe accident conditions (VEGA group). The research conducted in the year 2001 produced many important data and information. They are, for example, the fuel behavior data under BWR power oscillation conditions in the NSRR, the data on failure-bearing capability of hydrided cladding under LOCA conditions and the FP release data at very high temperature in steam which simulate the reactor core condition during severe accidents. This report summarizes the outline of research activities and major outcomes of the research executed in 2001 in the Fuel Safety Research Laboratory. (author)

  15. Fuel Exhaling Fuel Cell. (United States)

    Manzoor Bhat, Zahid; Thimmappa, Ravikumar; Devendrachari, Mruthyunjayachari Chattanahalli; Kottaichamy, Alagar Raja; Shafi, Shahid Pottachola; Varhade, Swapnil; Gautam, Manu; Thotiyl, Musthafa Ottakam


    State-of-the-art proton exchange membrane fuel cells (PEMFCs) anodically inhale H 2 fuel and cathodically expel water molecules. We show an unprecedented fuel cell concept exhibiting cathodic fuel exhalation capability of anodically inhaled fuel, driven by the neutralization energy on decoupling the direct acid-base chemistry. The fuel exhaling fuel cell delivered a peak power density of 70 mW/cm 2 at a peak current density of 160 mA/cm 2 with a cathodic H 2 output of ∼80 mL in 1 h. We illustrate that the energy benefits from the same fuel stream can at least be doubled by directing it through proposed neutralization electrochemical cell prior to PEMFC in a tandem configuration.

  16. Thin film properties of sputtered niobium silicide on SiO/sub 2/, Si/sub 3/N/sub 4/, and N/sup +/ poly-Si

    Energy Technology Data Exchange (ETDEWEB)

    Chow, T.P.; Lu, W.J.; Steckl, A.J.; Baliga, B.J.


    Thin film properties of niobium silicide sputtered from a slightly silicon-rich (Si/Nb approx. = 2.3), cold-pressed alloy target onto SiO/sub 2/, Si/sub 3/N/sub 4/, and n doped poly-Si have been investigated. The structural and compositional properties were examined with x-ray diffraction, Rutherford backscattering spectrometry (RBS), and secondary ion mass spectrometry (SIMS). X-ray diffraction revealed that NbSi/sub 2/ was the predominant silicide phase present, unlike those films reported previously, which contained significant amounts of an intermediate silicide phase (Nb/sub 5/Si/sub 3/). These films had a SiNb ratio of 2.1 as determined from RBS and contained lower levels of common contaminants (such as N/sub 2/, O/sub 2/, and carbon). Isochronal and isothermal annealing showed that the major decrease in resistivity occurred in the first 5 min, and a resistivity value of approx. =70 cap omega..-cm was obtained after annealing at 1000/sup 0/C. During annealing, phosphorus was found to diffuse through NbSi/sub 2/ rapidly, similar to other refractory silicides.

  17. Formation and thermal stability of Ti-capped Co-silicide from Co-Ta alloy films on (100) Si and polycrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Joo; Choi, Hyo Jick; Ko, Dae Hong [Yonsei Univ., Seoul (Korea, Republic of); Ku, Ja Hum; Choi, Si Young; Fujihara, Kazuyuki [Samsung Electronics Co., Ltd., Yongin (Korea, Republic of); Yang, Cheol Woong [Sungkyunkwan Univ., Suwon (Korea, Republic of)


    Co-Ta alloy films were deposited on (100) single-crystalline and polycrystalline silicon substrates by using DC magnetron sputtering. The interfacial reactions between the Co-Ta alloy films and the silicon substrates were investigated in the temperature range of 500 {approx} 820 degree C by using rapid thermal annealing in an N{sub 2} ambient. In contrast to the Co/si system, we observed that the formation of Co-silicide and the transformation from the high resistivity CoSi phase to the low resistivity CoSi{sub 2} phase in the Co-Ta/Si system occurred at higher temperatures than it did in the Co/Si system. The Co-silicide films on Si and poly-Si substrates formed from Co-Ta alloy films maintained low sheet resistance values upon high temperature annealing while those of Co-silicide films from the Co/Si system increased significantly. The improvement in the thermal stability of the Co-silicide films formed from Co-Ta alloy films is due to the formation of Ta-compounds, such as the TaSi{sub 2} phase, at the grain boundaries and at the surfaces of the CoSi{sub 2} films.

  18. Study of Maxwell–Wagner (M–W) relaxation behavior and hysteresis observed in bismuth titanate layered structure obtained by solution combustion synthesis using dextrose as fuel

    Energy Technology Data Exchange (ETDEWEB)

    Subohi, Oroosa, E-mail: [Department of Physics, Maulana Azad National Institute of Technology, Bhopal 462051, M.P. (India); Shastri, Lokesh [Department of Physics, Maulana Azad National Institute of Technology, Bhopal 462051, M.P. (India); Kumar, G.S. [Department of Physics, Osmania University, Hyderabad 500007, A.P. (India); Malik, M.M.; Kurchania, Rajnish [Department of Physics, Maulana Azad National Institute of Technology, Bhopal 462051, M.P. (India)


    Graphical abstract: X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T{sub c}) to be 650 °C. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample. - Highlights: • Bi{sub 4}Ti{sub 3}O{sub 12} is synthesized using solution combustion technique with dextrose as fuel. • Dextrose has high reducing capacity (+24) and generates more no. of moles of gases. • Impedance studies show that the sample follows Maxwell–Wagner relaxation behavior. • Shows lower remnant polarization due to higher c-axis ratio. - Abstract: Structural, dielectric and ferroelectric properties of bismuth titanate (Bi{sub 4}Ti{sub 3}O{sub 12}) obtained by solution combustion technique using dextrose as fuel is studied extensively in this paper. Dextrose is used as fuel as it has high reducing valancy and generates more number of moles of gases during the reaction. X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T{sub c}) to be 650 °C. The dielectric loss is very less (tan δ < 1) at lower temperatures but increases around T{sub c} due to structural changes in the sample. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample.

  19. Performance and fuel-cycle cost analysis of one JANUS 30 conceptual design for several fuel-element-design options

    Energy Technology Data Exchange (ETDEWEB)

    Nurdin, M.; Matos, J.E.; Freese, K.E.


    The performance and fuel cycle costs for a 25 MW, JANUS 30 reactor conceptual design by INTERATOM, Federal Republic of Germany, for BATAN, Republic of Indonesia have been studied using 19.75% enriched uranium in four fuel element design options. All of these fuel element designs have either been proposed by INTERATOM for various reactors or are currently in use with 93% enriched uranium in reactors in the Federal Republic of Germany. Aluminide, oxide, and silicide fuels were studied for selected designs using the range of uranium densities that are either currently qualified or are being developed and demonstrated internationally. To assess the long-term fuel adaptation strategy as well as the present fuel acceptance, reactor performance and annual fuel cycle costs were computed for seventeen cases based on a representative end-of-cycle excess reactivity and duty factor. In addition, a study was made to provide data for evaluating the trade-off between the increased safety associated with thicker cladding and the economic penalty due to increased fuel consumption.

  20. Narrow bandgap semiconducting silicides: Intrinsic infrared detectors on a silicon chip (United States)

    Mahan, John E.


    Work done during the final report period is presented. The main technical objective was to achieve epitaxial growth on silicon of two semiconducting silicides, ReSi2 and CrSi2. ReSi2 thin films were grown on (001) silicon wafers by vacuum evaporation of rhenium onto hot substrates in ultrahigh vacuum. The preferred epitaxial relationship was found to be ReSi2(100)/Si(001) with ReSi2(010) parallel to Si(110). The lattice matching consists of a common unit mesh of 120 A(sup 2) area, and a mismatch of 1.8 percent. Transmission electron microscopy revealed the existence of rotation twins corresponding to two distinct but equivalent azimuthal orientations of the common unit mesh. MeV He(+) backscattering spectrometry revealed a minimum channeling yield of 2 percent for an approximately 1,500 A thick film grown at 650 C. Although the lateral dimension of the twins is on the order of 100 A, there is a very high degree of alignment between the ReSi2(100) and the Si(001) planes. Highly oriented films of CrSi2 were grown on (111) silicon substrates, with the matching crystallographic faces being CrSi2(001)/Si(111). The reflection high-energy electron diffraction (RHEED) patterns of the films consist of sharp streaks, symmetrically arranged. The predominant azimuthal orientation of the films was determined to be CrSi2(210) parallel to Si(110). This highly desirable heteroepitaxial relationship has been obtained previously by others; it may be described with a common unit mesh of 51 A(sup 2) and mismatch of 0.3 percent. RHEED also revealed the presence of limited film regions of a competing azimuthal orientation, CrSi2(110) parallel to Si(110). A channeling effect for MeV He(+) ions was not found for this material. Potential commercial applications of this research may be found in silicon-integrated infrared detector arrays. Optical characterizations showed that semiconducting ReSi2 is a strong absorber of infrared radiation, with the adsorption constant increasing above 2 x

  1. Fuel for Fun: a cluster-randomized controlled study of cooking skills, eating behaviors, and physical activity of 4th graders and their families

    Directory of Open Access Journals (Sweden)

    Leslie Cunningham-Sabo


    Full Text Available Abstract Background Childhood obesity remains a serious concern in the United States and in many other countries. Direct experience preparing and tasting healthful foods and increasing activity during the school day are promising prevention approaches. Engaging parents and families remains an important challenge. Fuel for Fun: Cooking with Kids Plus Parents and Play is a multi-component school- and family-based intervention for 4th graders and their families intended to promote positive food and activity environments, policies and behaviors at the individual, family and school levels. This paper describes the design and evaluation plan. Methods/Design Four cohorts of 4th-graders and their parents from 8 schools in 2 districts in the same Northern Colorado region are participating in a 4-arm cluster randomized controlled trial. Theory-based Fuel for Fun consists of 5 components delivered over 1 school year: 1 Cooking with Kids - Colorado; an experiential classroom-based cooking and tasting curriculum, 2 Cafeteria Connections; cafeteria-based reinforcements of classroom food experiences using behavioral economic strategies, 3 SPARK active recess; a playground intervention to engage children in moderate to vigorous activity, 4 Fuel for Fun Family; multi-element supports targeting parents to reinforce the 3 school-based components at home, and 5 About Eating; an online interactive program for parents addressing constructs of eating competence and food resource management. Outcomes include child and parent measures of fruit and vegetable preferences and intake, cooking, physical activity, sedentary behaviors and attitudes. School level data assess lunch plate waste and physical activity at recess. In-depth diet and accelerometry assessments are collected with a subsample of parent-child dyads. Data are collected at baseline, immediately post-intervention at 7 months, and at 12 month follow-up. We anticipate recruiting 1320–1584 children and their

  2. Co-combustion of pulverized coal and solid recovered fuel in an entrained flow reactor- General combustion and ash behavior

    DEFF Research Database (Denmark)

    Wu, Hao; Glarborg, Peter; Frandsen, Flemming


    of the additives increased the S-retention in ash. Analysis of the bulk composition of fly ash from different experiments indicated that the majority of S and Cl in the fuels were released to gas phase during combustion, whereas the K and Na in the fuels were mainly retained in ash. When co-firing coal and SRF...... propensity in co-combustion was decreased with increasing share of SRF. The addition of NaCl and PVC significantly increased the ash deposition propensity, whereas the addition of ammonium sulphate or kaolinite showed a slight reducing effect. The chlorine content in the deposits generally implied a low...

  3. Investigation of feedback on neutron kinetics and thermal hydraulics from detailed online fuel behavior modeling during a boron dilution transient in a PWR with the two-way coupled code system DYN3D-TRANSURANUS

    Energy Technology Data Exchange (ETDEWEB)

    Holt, L., E-mail: [TÜV SÜD Energietechnik GmbH Baden-Württemberg, Gottlieb-Daimler-Str. 7, 70794 Filderstadt (Germany); Technical University München, Department of Nuclear Engineering, Boltzmannstr. 15, D-85748 Garching bei München (Germany); Rohde, U.; Kliem, S.; Baier, S. [Helmholtz-Zentrum Dresden—Rossendorf, Reactor Safety Division, PO Box 510119, D-01314 Dresden (Germany); Seidl, M. [E.ON Kernkraft GmbH, Tresckowstr. 5, D-30457 Hannover (Germany); Van Uffelen, P. [European Commission, Joint Research Centre, Institute for Transuranium Elements, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Macián-Juan, R. [Technical University München, Department of Nuclear Engineering, Boltzmannstr. 15, D-85748 Garching bei München (Germany)


    Highlights: • General coupling interface was developed for the fuel performance code TRANSURANUS. • With this new tool simplified fuel behavior models in codes can be replaced. • The reactor dynamics code DYN3D was coupled to TRANSURANUS at assembly level. • The feedback from detailed online fuel behavior modeling is analyzed for reactivity initiated accident (RIA). • The thermal hydraulics can be affected strongly even in fresh fuel assemblies. - Abstract: Recently the reactor dynamics code DYN3D (including an internal fuel behavior model) was coupled to the fuel performance code TRANSURANUS at assembly level. The coupled code system applies the new general TRANSURANUS coupling interface, hence it can be used for one-way or two-way coupling. In the coupling, DYN3D provides process time, time-dependent rod power and thermal hydraulics conditions to TRANSURANUS, which in case of the two-way coupling approach replaces completely the internal DYN3D fuel behavior model and transfers parameters like radial fuel temperature distribution and cladding temperature back to DYN3D. For the first time results of the coupled code system are presented for a post-critical-heat-flux heat transfer. The corresponding heat transfer regime is mostly film boiling, where the cladding temperature can rise several hundreds of degrees. The simulated boron dilution transient assumed an injection of a 36 m{sup 3} slug of under-borated coolant into a German pressurized water reactor (PWR) core initiated from a sub-critical reactor state (extreme reactivity initiated accident (RIA) conditions). The feedback from detailed fuel behavior modeling was found negligible on the neutron kinetics and thermal hydraulics during the first power rise. In a later phase of the transient, the node injected energy can differ 25 J/g, even still around 20 J/g for nodes without film boiling. Furthermore, the thermal hydraulics can be affected strongly even in fresh fuel assemblies, where film boiling

  4. Dry Process Fuel Performance Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Myung Seung; Song, K. C.; Moon, J. S. and others


    The objective of the project is to establish the performance evaluation system of DUPIC fuel during the Phase II R and D. In order to fulfil this objectives, irradiation test of DUPIC fuel was carried out in HANARO using the non-instrumented and SPND-instrumented rig. Also, the analysis on the in-reactor behavior analysis of DUPIC fuel, out-pile test using simulated DUPIC fuel as well as performance and integrity assessment in a commercial reactor were performed during this Phase. The R and D results of the Phase II are summarized as follows : - Performance evaluation of DUPIC fuel via irradiation test in HANARO - Post irradiation examination of irradiated fuel and performance analysis - Development of DUPIC fuel performance code (modified ELESTRES) considering material properties of DUPIC fuel - Irradiation behavior and integrity assessment under the design power envelope of DUPIC fuel - Foundamental technology development of thermal/mechanical performance evaluation using ANSYS (FEM package)

  5. Fossil fuels -- future fuels

    Energy Technology Data Exchange (ETDEWEB)



    Fossil fuels -- coal, oil, and natural gas -- built America`s historic economic strength. Today, coal supplies more than 55% of the electricity, oil more than 97% of the transportation needs, and natural gas 24% of the primary energy used in the US. Even taking into account increased use of renewable fuels and vastly improved powerplant efficiencies, 90% of national energy needs will still be met by fossil fuels in 2020. If advanced technologies that boost efficiency and environmental performance can be successfully developed and deployed, the US can continue to depend upon its rich resources of fossil fuels.

  6. Oxidation at through-hole defects in fused slurry silicide coated columbium alloys FS-85 and Cb-752 (United States)

    Levine, S. R.


    Metal recession and interstitial contamination at 0.08-centimeter-diameter through-hole intentional defects in fused slurry silicide coated FS-85 and Cb-752 columbium alloys were studied to determine the tolerance of these materials to coating defects. Five external pressure reentry simulation exposures to 1320 C and 4.7 x 1,000 N/sq m (maximum pressure) resulted in a consumed metal zone having about twice the initial defect diameter for both alloys with an interstitial contamination zone extending about three to four initial defect diameters. Self-healing occurred in the 1.33 x 10 N/sq m, 1320 C exposures and to a lesser extent in internal pressure reentry cycles to 1320 C and 1.33 x 100 N/sq m (maximum pressure).

  7. Interdiffusion and growth of chromium silicide at the interface of Cr/Si(As) system during rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Benkherbache, H. [Universite de M' Sila, (28000) M' Sila (Algeria); Merabet, A., E-mail: merabet_abdelali@yahoo.f [Laboratoire Physique et Mecanique des Materiaux Metalliques, Departement d' O.M.P., Faculte des Sciences de l' Ingenieur, Universite de Setif, (19000) Setif (Algeria)


    In this work, the solid-state reaction between a thin film of chromium and silicon has been studied using Rutherford backscattering spectroscopy, X-ray diffraction and the sheet resistance measurements. The thickness of 100 nm chromium layer has been deposited by electronic bombardment on Si (100) substrates, part of them had previously been implanted with arsenic ions of 10{sup 15} at/cm{sup 2} doses and an energy of 100 keV. The samples were heat treated under rapid thermal annealing at 500 {sup o}C for time intervals ranging from 15 to 60 s. The rapid thermal annealing leads to a reaction at the interface Cr/Si inducing the formation and the growth of the unique silicide CrSi{sub 2}, but no other phase can be detected. For samples implanted with arsenic, the saturation value of the sheet resistance is approximately 1.5 times higher than for the non-implanted case.

  8. Summary report on fuel development and miniplate fabrication for the RERTR Program, 1978 to 1990

    Energy Technology Data Exchange (ETDEWEB)

    Wiencek, T.C. [Argonne National Lab., IL (United States). Energy Technology Div.


    This report summarizes the efforts of the Fabrication Technology Section at Argonne National Laboratory in the program of Reduced Enrichment Research and Test Reactors (RERTR). The main objective of this program was to reduce the amount of high enriched ({approx}93% {sup 235}U) uranium (HEU) used in nonpower reactors. Conversion from low-density (0.8--1.6 g U/cm{sup 3}) HEU fuel elements to highly loaded (up to 7 g U/cm{sup 3}) low-enrichment (<20% {sup 235}U) uranium (LEU) fuel elements allows the same reactor power levels, core designs and sizes to be retained while greatly reducing the possibility of illicit diversion of HEU nuclear fuel. This document is intended as an overview of the period 1978--1990, during which the Section supported this project by fabricating mainly powder metallurgy uranium-silicide dispersion fuel plates. Most of the subjects covered in detail are fabrication-related studies of uranium silicide fuels and fuel plate properties. Some data are included for out-of-pile experiments such as corrosion and compatibility tests. Also briefly covered are most other aspects of the RERTR program such as irradiation tests, full-core demonstrations, and technology transfer. References included are for further information on most aspects of the entire program. A significant portion of the report is devoted to data that were never published in their entirety. The appendices contain a list of previous RERTR reports, ANL fabrication procedures, calculations for phases present in two-phase fuels, chemical analysis of fuels, miniplate characteristics, and a summary of bonding runs made by hot isostatic pressing.

  9. Impact of fuel molecular structure on auto-ignition behavior – Design rules for future high performance gasolines

    KAUST Repository

    Boot, Michael D.


    At a first glance, ethanol, toluene and methyl tert-butyl ether look nothing alike with respect to their molecular structures. Nevertheless, all share a similarly high octane number. A comprehensive review of the inner workings of such octane boosters has been long overdue, particularly at a time when feedstocks for transport fuels other than crude oil, such as natural gas and biomass, are enjoying a rapidly growing market share. As high octane fuels sell at a considerable premium over gasoline, diesel and jet fuel, new entrants into the refining business should take note and gear their processes towards knock resistant compounds if they are to maximize their respective bottom lines. Starting from crude oil, the route towards this goal is well established. Starting from biomass or natural gas, however, it is less clear what dots on the horizon to aim for. The goal of this paper is to offer insight into the chemistry behind octane boosters and to subsequently distill from this knowledge, taking into account recent advances in engine technology, multiple generic design rules that guarantee good anti-knock performance. Careful analysis of the literature suggests that highly unsaturated (cyclic) compounds are the preferred octane boosters for modern spark-ignition engines. Additional side chains of any variety will dilute this strong performance. Multi-branched paraffins come in distant second place, owing to their negligible sensitivity. Depending on the type and location of functional oxygen groups, oxygenates can have a beneficial, neutral or detrimental impact on anti-knock quality.

  10. Atomization of broad specification aircraft fuels (United States)

    Skifstad, J. G.; Lefebvre, A. H.


    The atomization properties of liquid fuels for the potential use in aircraft gas turbine engines are discussed. The significance of these properties are addressed with respect to the ignition and subsequent combustion behavior of the fuel spray/air mixture. It is shown that the fuel properties which affect the atomization behavior (viscosity, surface tension, and density) are less favorable for the broad specification fuels as compared to with those for conventional fuels.

  11. Effect of P{sup +} ions on the microstructure and the nature of the formed silicides in the Cr/Si system

    Energy Technology Data Exchange (ETDEWEB)

    Mirouh, K. [Laboratoire des Couches Minces et Interfaces, Departement de Physique, Universite de Constantine, Campus chaab Errassas, Constantine 25000 (Algeria)]. E-mail:; Bouabellou, A. [Laboratoire des Couches Minces et Interfaces, Departement de Physique, Universite de Constantine, Campus chaab Errassas, Constantine 25000 (Algeria); Halimi, R. [Laboratoire des Couches Minces et Interfaces, Departement de Physique, Universite de Constantine, Campus chaab Errassas, Constantine 25000 (Algeria); Karaali, A. [Laboratoire des Couches Minces et Interfaces, Departement de Physique, Universite de Constantine, Campus chaab Errassas, Constantine 25000 (Algeria); Mosser, A. [IPCMS-GSI, 23 rue du Loess, F-67037 Strasbourg (France); Ehret, G. [IPCMS-GSI, 23 rue du Loess, F-67037 Strasbourg (France)


    The effect of the phosphorus on the microstructure and on the nature of the formed silicide in the annealed Cr/Si system is studied. The chromium layer is deposited by electron gun evaporation on the undoped and P{sup +} doped monocrystalline silicon. Cross-sectional transmission electron microscopy (XTEM) investigation of the samples, annealed at 475 deg. C for different times, shows that the presence of phosphorus leads to the formation of CrSi{sub 2} disilicide, free of defects, and Cr{sub 3}Si silicide for lower and higher annealing times, respectively. In the case of undoped substrate the formed CrSi{sub 2} disilicide is stable and contains a high concentration of stacking faults when the chromium is partially consumed.

  12. FLIT-MLO and No. 2 fuel oil: Effects of aerosol applications to mallard eggs on hatchability and behavior of ducklings (United States)

    Albers, P.H.; Heinz, G.H.


    FLIT-MLO and No. 2 fuel oil are sprayed on wetlands for mosquito control during spring and summer. In one experiment to assess the effects of the spraying on birds, mallard eggs were sprayed with amounts of No. 2 fuel oil equivalent to 2.34, 4.67, or 18.70 liters/ha or FLIT-MLO equivalent to 9.35, 46.75, or 140.25 liters/ha on Day 6 of incubation. In a second experiment, mallard eggs were sprayed with 9.35, 46.75, or 140.25 liters/ha of FLIT-MLO on Days 3, 6, 12, or 18 of incubation. Hatchability of eggs sprayed with the highest treatment level of each substance was significantly lower than that of controls for the first experiment. Hatchability of eggs sprayed with FLIT-MLO in the second experiment was never significantly lower than that of controls. Ducklings from the first experiment, 36-48 hr old, were cold stressed for 1 hr at 8 degrees C and then immediately tested for their ability to respond to a fright stimulus. Ducklings from the group of eggs sprayed with 140.25 liters/ha of FLIT-MLO ran a significantly shorter distance from the fright stimulus than did controls. The effects of the heaviest exposure to FLIT-MLO (140.25 liters/ha) on egg hatchability and behavior of newly hatched young are uncertain because of the contradictory results for hatching success in the two experiments. However, normal applications of FLIT-MLO (9.35-46.75 liters/ha) or No. 2 fuel oil (2.34-4.67 liters/ha) do not appear to pose a threat to the embryos of breeding birds.

  13. Role of Chloride in the Corrosion and Fracture Behavior of Micro-Alloyed Steel in E80 Simulated Fuel Grade Ethanol Environment

    Directory of Open Access Journals (Sweden)

    Olufunmilayo O. Joseph


    Full Text Available In this study, micro-alloyed steel (MAS material normally used in the production of auto parts has been immersed in an E80 simulated fuel grade ethanol (SFGE environment and its degradation mechanism in the presence of sodium chloride (NaCl was evaluated. Corrosion behavior was determined through mass loss tests and electrochemical measurements with respect to a reference test in the absence of NaCl. Fracture behavior was determined via J-integral tests with three-point bend specimens at an ambient temperature of 27 °C. The mass loss of MAS increased in E80 with NaCl up to a concentration of 32 mg/L; beyond that threshold, the effect of increasing chloride was insignificant. MAS did not demonstrate distinct passivation behavior, as well as pitting potential with anodic polarization, in the range of the ethanol-chloride ratio. Chloride caused pitting in MAS. The fracture resistance of MAS reduced in E80 with increasing chloride. Crack tip blunting decreased with increasing chloride, thus accounting for the reduction in fracture toughness.

  14. Behavior of U3Si2 Fuel and FeCrAl Cladding under Normal Operating and Accident Reactor Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle Allan Lawrence [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, Jason Dean [Idaho National Lab. (INL), Idaho Falls, ID (United States); Barani, Tommaso [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pizzocri, Davide [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pastore, Giovanni [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    As part of the Department of Energy's Nuclear Energy Advanced Modeling and Simulation program, an Accident Tolerant Fuel High Impact Problem was initiated at the beginning of fiscal year 2015 to investigate the behavior of \\usi~fuel and iron-chromium-aluminum (FeCrAl) claddings under normal operating and accident reactor conditions. The High Impact Problem was created in response to the United States Department of Energy's renewed interest in accident tolerant materials after the events that occurred at the Fukushima Daiichi Nuclear Power Plant in 2011. The High Impact Problem is a multinational laboratory and university collaborative research effort between Idaho National Laboratory, Los Alamos National Laboratory, Argonne National Laboratory, and the University of Tennessee, Knoxville. This report primarily focuses on the engineering scale research in fiscal year 2016 with brief summaries of the lower length scale developments in the areas of density functional theory, cluster dynamics, rate theory, and phase field being presented.

  15. Behaviorism

    National Research Council Canada - National Science Library

    Moore, J


    .... Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the observational methods common to all sciences...

  16. Morphological and electrical properties of self-assembled iron silicide nanoparticles on Si(0 0 1) and Si(1 1 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Molnár, G., E-mail:; Dózsa, L.; Erdélyi, R.; Vértesy, Z.; Osváth, Z.


    Highlights: • Epitaxial iron silicide nanostructures were grown on Si(1 1 1) and Si(0 0 1) substrates. • The size and shape of the particles are the function of the thickness and annealing. • The local current–voltage characteristics were measured by conductive AFM. • The different size and shape nanoparticles show similar I–V characteristics. • The tip current is dominated in few nm size sites, visible in the AFM phase image. - Abstract: Epitaxial iron silicide nanostructures are grown by solid phase epitaxy on Si(0 0 1) and Si(1 1 1), and by reactive deposition epitaxy on Si(0 0 1) substrates. The formation process is monitored by reflection high-energy electron diffraction. The morphology, size, and electrical properties of the nanoparticles are investigated by scanning electron microscopy, by electrically active scanning probe microscopy, and by confocal Raman spectroscopy. The results show that the shape, size, orientation, and density of the nanoobjects can be tuned by self-assembly, controlled by the lattice misfit between the substrates and iron silicides. The size distribution and shape of the grown nanoparticles depend on the substrate orientation, on the initial thickness of the evaporated iron, on the temperature and time of the annealing, and on the preparation method. The so-called Ostwald ripening phenomena, which state that the bigger objects develop at the expense of smaller ones, controls the density of the nanoparticles. Raman spectra show the bigger objects do not contain β-FeSi{sub 2} phase. The different shape nanoparticles exhibit small, about 100 mV barrier compared to the surrounding silicon. The local leakage current of the samples measured by conductive AFM using a Pt coated Si tip is localized in a few nanometers size sites, and the sites which we assume are very small silicide nanoparticles or point defects.

  17. Simultaneous aluminizing and chromizing of steels to form (Fe,Cr){sub 3}Al coatings and Ge-doped silicide coatings of Cr-Zr base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, M.; He, Y.R.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering


    A halide-activated cementation pack involving elemental Al and Cr powders has been used to achieve surface compositions of approximately Fe{sub 3}Al plus several percent Cr for low alloy steels (T11, T2 and T22) and medium carbon steel (1045 steel). A two-step treatment at 925 C and 1150 C yields the codeposition and diffusion of aluminum and chromium to form dense and uniform ferrite coatings of about 400 {micro}m thickness, while preventing the formation of a blocking chromium carbide at the substrate surfaces. Upon cyclic oxidation in air at 700 C, the coated steel exhibits a negligible 0.085 mg/cm{sup 2} weight gain for 1900 one-hour cycles. Virtually no attack was observed on coated steels tested at ABB in simulated boiler atmospheres at 500 C for 500 hours. But coatings with a surface composition of only 8 wt% Al and 6 wt% Cr suffered some sulfidation attack in simulated boiler atmospheres at temperatures higher than 500 C for 1000 hours. Two developmental Cr-Zr based Laves phase alloys (CN129-2 and CN117(Z)) were silicide/germanide coated. The cross-sections of the Ge-doped silicide coatings closely mimicked the microstructure of the substrate alloys. Cyclic oxidation in air at 1100 C showed that the Ge-doped silicide coating greatly improved the oxidation resistance of the Cr-Zr based alloys.

  18. An investigation into the transient behavior of a microreactor system for reforming of Diesel fuel in the kw range

    Energy Technology Data Exchange (ETDEWEB)

    Kolb, G.; Schelhaas, K.P.; Schuerer, J.; Tiemann, D.; Ziogas, A. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Hessel, V. [Institut fuer Mikrotechnik Mainz GmbH, Mainz (Germany); Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (Netherlands); O' Connell, M.


    A diesel reformer based on microreaction technology was developed for application in an auxiliary power unit (APU) system. The transient characteristics of this reactor for reforming of diesel fuel are reported. Diesel steam reforming was performed at various S/C ratios with load changes ranging from 30 % LL to 80 % LL, i.e., a 1.5 kW to a 4 kW electrical equivalent. The reactor itself was based on an integrated reformer/burner heat exchange reactor concept. The reforming was performed at temperatures above 750 C and at various S/C ratios, down to a minimum of 3.17. Variation of experimental parameters, such as O/C and S/C ratios, are critical for optimum and efficient operation of the reformer. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. Fuels and fire behavior in chipped and unchipped plots: implications for land management near the wildland/urban interface (United States)

    Jeff S. Glitzenstein; Donna R. Streng; Gary L. Achtemeier; Luke P. Naeher; Dale D. Wade


    Fire behavior was measured and modeled from eight 1 ha experimental plots located in the Francis Marion National Forest, South Carolina, during prescribed burns on February 12 and February 20, 2003. Four of the plots had been subjected to mechanical chipping during 2002 to remove woody understory growth and to reduce large downed woody debris from the aftermath of...

  20. Research on high-temperature compression and creep behavior of porous Cu–Ni–Cr alloy for molten carbonate fuel cell anodes

    Directory of Open Access Journals (Sweden)

    Li W.


    Full Text Available The effect of porosity on high temperature compression and creep behavior of porous Cu alloy for the new molten carbonate fuel cell anodes was examined. Optical microscopy and scanning electron microscopy were used to investigate and analyze the details of the microstructure and surface deformation. Compression creep tests were utilized to evaluate the mechanical properties of the alloy at 650 °C. The compression strength, elastic modulus, and yield stress all increased with the decrease in porosity. Under the same creep stress, the materials with higher porosity exhibited inferior creep resistance and higher steadystate creep rate. The creep behavior has been classified in terms of two stages. The first stage relates to grain rearrangement which results from the destruction of large pores by the applied load. In the second stage, small pores are collapsed by a subsequent sintering process under the load. The main deformation mechanism consists in that several deformation bands generate sequentially under the perpendicular loading, and in these deformation bands the pores are deformed by flattering and collapsing sequentially. On the other hand, the shape of a pore has a severe influence on the creep resistance of the material, i.e. every increase of pore size corresponds to a decrease in creep resistance.

  1. Analysis of South Carolina hydrogen and fuel cell workers views and opinion leadership behavior: A waiting opportunity?

    Energy Technology Data Exchange (ETDEWEB)

    Besley, John C. [School of Journalism and Mass Communications, University of South Carolina, Columbia, SC 29205 (United States); Baxter-Clemmons, Shannon [South Carolina Hydrogen Fuel Cell Alliance, P.O. Box 12302, Columbia, SC 29201 (United States)


    The current study uses quantitative survey results to explore what a near census of hydrogen and fuel cell (HFC) workers in South Carolina (n = 70) say about their HFC experiences and the degree to which these workers can be expected to act as opinion leaders for the field. In general, these workers say they are positive about the environmental, national security, and economic potential of HFC technologies. They further see HFC technologies as having small and manageable levels of risk. A number of these workers exhibit characteristics associated with both issue-specific and general opinion leadership. Issue-specific leadership and positive views about HFC technology were associated with higher levels of self-reported technology-related interpersonal discussion. The study concludes that the existence of workers with positive HFC experiences and a demonstrated interest in telling others about their experiences may represent an opportunity for those charged with promoting HFC development and adoption. Future efforts should explore how HFC workers could be effectively integrated into such efforts as a means of reaching difficult to reach audiences. (author)

  2. Behaviorism (United States)

    Moore, J.


    Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

  3. Role of metal/silicon semiconductor contact engineering for enhanced output current in micro-sized microbial fuel cells

    KAUST Repository

    Mink, Justine E.


    We show that contact engineering plays an important role to extract the maximum performance from energy harvesters like microbial fuel cells (MFCs). We experimented with Schottky and Ohmic methods of fabricating contact areas on silicon in an MFC contact material study. We utilized the industry standard contact material, aluminum, as well as a metal, whose silicide has recently been recognized for its improved performance in smallest scale integration requirements, cobalt. Our study shows that improvements in contact engineering are not only important for device engineering but also for microsystems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Effect of deposition conditions on the structure, phase composition and electrical properties of the chromium silicide films

    Energy Technology Data Exchange (ETDEWEB)

    Trofimov, V I [Institute of Radioengineering and Electronics, 11/7 Mokhovaya Str., 125009 Moscow (Russian Federation); Kim, J [CN-Regional Innovation Agency, 244-19 Songgok-ri, Asan City, 336-813 (Korea, Republic of); Bae, S [University of Incheon, 177 Dohwa-Dong, Incheon City, 402-749 (Korea, Republic of)], E-mail:


    Thin chromium silicide films with thickness up to 20 nm were deposited by flash evaporation of CrSi{sub 2} powder onto silica glass and (100) KCl substrates at temperatures from 20 to 550{sup 0}C and analyzed by electrical resistance measurements and transmission electron microscopy. The film phase composition depends crucially on deposition procedure: if a CrSi{sub 2} powder was thermally treated just prior deposition, CrSi{sub 2} film grows otherwise Cr{sub 3}Si film is formed. Under deposition onto unheated substrate an amorphous film grows. A crystalline phase appears at {approx}280 deg. C for CrSi{sub 2} and 250 deg. C for Cr{sub 3}Si and furtheron its fraction increases. The CrSi{sub 2} film consists of densely packed crystallites, whereas Cr{sub 3}Si film structure resembles a network of fine crystallites imbedded into amorphous silicon-based matrix. The resistivity of CrSi{sub 2} film grows with substrate temperature, whereas that of Cr{sub 3}Si film reduces. The observed resistivity - film thickness dependence is well described by the Fuchs-Sondheimer model for CrSi{sub 2} films and Mayadas-Shatzkes model for Cr{sub 3}Si films, since in the formers the crystallites size is larger than a film thickness, whereas in the latter's it is less than a film thickness.

  5. Effect of deposition conditions on the structure, phase composition and electrical properties of the chromium silicide films (United States)

    Trofimov, V. I.; Kim, J.; Bae, S.


    Thin chromium silicide films with thickness up to 20 nm were deposited by flash evaporation of CrSi2 powder onto silica glass and (100) KCl substrates at temperatures from 20 to 550°C and analyzed by electrical resistance measurements and transmission electron microscopy. The film phase composition depends crucially on deposition procedure: if a CrSi2 powder was thermally treated just prior deposition, CrSi2 film grows otherwise Cr3Si film is formed. Under deposition onto unheated substrate an amorphous film grows. A crystalline phase appears at ~280°C for CrSi2 and 250°C for Cr3Si and furtheron its fraction increases. The CrSi2 film consists of densely packed crystallites, whereas Cr3Si film structure resembles a network of fine crystallites imbedded into amorphous silicon-based matrix. The resistivity of CrSi2 film grows with substrate temperature, whereas that of Cr3Si film reduces. The observed resistivity - film thickness dependence is well described by the Fuchs-Sondheimer model for CrSi2 films and Mayadas-Shatzkes model for Cr3Si films, since in the formers the crystallites size is larger than a film thickness, whereas in the latter's it is less than a film thickness.

  6. Mechanical properties of thermoelectric n-type magnesium silicide synthesized employing in situ spark plasma reaction sintering (United States)

    Muthiah, Saravanan; Singh, R. C.; Pathak, B. D.; Dhar, Ajay


    Thermoelectric devices employing magnesium silicide (Mg2Si) offer an inexpensive and non-toxic solution for green energy generation compared to other existing conventional thermoelectric materials in the mid-temperature range. However, apart from the thermoelectric performance, their mechanical properties are equally important in order to avoid the catastrophic failure of their modules during actual operation. In the present study, we report the synthesis of Mg2Si co-doped with Bi and Sb employing in situ spark plasma reaction sintering and investigate its broad range of mechanical properties. The mechanical properties of the sintered co-doped Mg2Si suggest a significantly enhanced value of hardness ~5.4  ±  0.2 GPa and an elastic modulus ~142.5  ±  6 GPa with a fracture toughness of ~1.71  ±  0.1 MPa  √m. The thermal shock resistance, which is one of the most vital parameter for designing thermoelectric devices, was found to be ~300 W m-1, which is higher than most of the other existing state-of-the-art mid-temperature thermoelectric materials. The friction and wear characteristics of sintered co-doped Mg2Si have been reported for the first time, in order to realize the sustainability of their thermoelectric modules under actual hostile environmental conditions.

  7. Density functional theory calculations of defect and fission gas properties in U-Si fuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Accident tolerant fuels (ATF) are being developed in response to the Fukushima Daiichi accident in Japan. One of the options being pursued is U-Si fuels, such as the U3Si2 and U3Si5 compounds, which benefit from high thermal conductivity (metallic) compared to the UO2 fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for U-Si fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap. The present study investigates point defect and fission gas properties in U3Si2, which is one of the main fuel candidates, using density functional theory (DFT) calculations. Based on a few assumption regarding entropy contributions, defect and fission diffusivities are predicted. Even though uranium silicides have been shown to amorphize easily at low temperature, we assume that U3Si2 remains crystalline under the conditions expected in Light Water Reactors (LWRs). The temperature and dose where amorphization occurs has not yet been well established.

  8. TEM and XAS investigation of fission gas behaviors in U-Mo alloy fuels through ion beam irradiation (United States)

    Zang, Hang; Yun, Di; Mo, Kun; Wang, Kunpeng; Mohamed, Walid; Kirk, Marquis A.; Velázquez, Daniel; Seibert, Rachel; Logan, Kevin; Terry, Jeffrey; Baldo, Peter; Yacout, Abdellatif M.; Liu, Wenbo; Zhang, Bo; Gao, Yedong; Du, Yang; Liu, Jing


    In this study, smaller-grained (hundred nano-meter size grain) and larger-grained (micro-meter size grain) U-10Mo specimens have been irradiated (implanted) with 250 keV Xe+ beam and were in situ characterized by TEM. Xe bubbles were not seen in the specimen after an implantation fluence of 2 × 1020 ions/m2 at room temperature. Nucleation of Xe bubbles happened during heating of the specimen to a final temperature of 300 °C. By comparing measured Xe bubble statistics, the nucleation and growth behaviors of Xe bubbles were investigated in smaller-grained and larger-grained U-10Mo specimens. A multi-atom kind of nucleation mechanism has been observed in both specimens. X-ray Absorption spectroscopy showed the edge position in the bubbles to be the same as that of Xe gas. The size of Xe bubbles has been shown to be bigger in larger-grained specimens than in smaller-grained specimens at the same implantation conditions.

  9. Effects of porous properties on cold-start behavior of polymer electrolyte fuel cells from sub-zero to normal operating temperatures (United States)

    Gwak, Geonhui; Ko, Johan; Ju, Hyunchul


    In this investigation, a parametric study was performed using the transient cold-start model presented in our previous paper, in which the ice melting process and additional constitutive relations were newly included for transient cold-start simulations of polymer electrolyte fuel cells (PEFCs) from a sub-zero temperature (-20°C) to a normal operating temperature (80°C). The focus is placed on exploring the transient cold-start behavior of a PEFC for different porous properties of the catalyst layer (CL) and gas diffusion layer (GDL). This work elucidates the detailed effects of these properties on key cold-start phenomena such as ice freezing/melting and membrane hydration/dehydration processes. In particular, the simulation results highlight that designing a cathode CL with a high ionomer fraction helps to retard the rate of ice growth whereas a high ionomer fraction in the anode CL is not effective to mitigate the anode dry-out and membrane dehydration issues during PEFC cold-start.

  10. Modification by H-termination in growth process of titanium silicide on Si(0 0 1)-2 x 1 observed with scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, T., E-mail: [Faculty of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan); Shudo, K.; Sato, K.; Ohno, S.; Nishioka, H.; Iida, T.; Toramaru, M.; Tanaka, M. [Faculty of Engineering, Yokohama National University, Tokiwadai 79-5, Hodogaya-ku, Yokohama 240-8501 (Japan)


    Formation processes of titanium silicide on hydrogen-terminated H/Si(0 0 1)-2 x 1 surface are studied at the atomic scale with a scanning tunneling microscopy (STM). Square-shaped nanoislands were observed on the Ti/H/Si(0 0 1) surface after annealed at 873-1073 K. These are the epitaxial nanoislands moderately grown due to the local orientation relationship between C49-TiSi{sub 2} and Si(0 0 1), because passivation by surface hydrogen on Si(0 0 1) suppresses active and complex bond formation of Ti-Si.

  11. Effect of Chemistry and Particle Size on the Performance of Calcium Disilicide Primers. Part 1 - Synthesis of Calcium Silicide (CaSi2) by Rotary Atomization (United States)


    reactions 1 and 2, respectively. A general rule of thumb for thermite reactions is that when the heat of formation per gram of product is lower than -1.6 kJ...34Calcium Silicide, CaSk" J. Chem. Soc Abstr. 82, II, 320, 1902. 2. Goldschmidt, H., "New Thermite Reactions, Iron Age, 82, 232, 1908. 3. MIL-C-324...Highway 361 Crane, IN 47522-5001 ATK Small Caliber System ATTN: M. Mansfield D. Clark R. Carpenter N. Tharp Lake City Army Ammunition Plant P.O. Box 1000 Independence, MO 64051-1000 16

  12. Effect of nickel silicide gettering on metal-induced crystallized polycrystalline-silicon thin-film transistors (United States)

    Kim, Hyung Yoon; Seok, Ki Hwan; Chae, Hee Jae; Lee, Sol Kyu; Lee, Yong Hee; Joo, Seung Ki


    Low-temperature polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) fabricated via metal-induced crystallization (MIC) are attractive candidates for use in active-matrix flat-panel displays. However, these exhibit a large leakage current due to the nickel silicide being trapped at the grain boundaries of the poly-Si. We reduced the leakage current of the MIC poly-Si TFTs by developing a gettering method to remove the Ni impurities using a Si getter layer and natively-formed SiO2 as the etch stop interlayer. The Ni trap state density (Nt) in the MIC poly-Si film decreased after the Ni silicide gettering, and as a result, the leakage current of the MIC poly-Si TFTs decreased. Furthermore, the leakage current of MIC poly-Si TFTs gradually decreased with additional gettering. To explain the gettering effect on MIC poly-Si TFTs, we suggest an appropriate model. He received the B.S. degree in School of Advanced Materials Engineering from Kookmin University, Seoul, South Korea in 2012, and the M.S. degree in Department of Materials Science and Engineering from Seoul National University, Seoul, South Korea in 2014. He is currently pursuing the Ph.D. degree with the Department of Materials Science and Engineering, Seoul National University, Seoul. He is involved in semiconductor device fabrication technology and top-gate polycrystalline-silicon thin-film transistors. He received the M.S. degree in innovation technology from Ecol Polytechnique, Palaiseau, France in 2013. He is currently pursuing the Ph.D. degree with the Department of Materials Science and Engineering, Seoul National University, Seoul. He is involved in semiconductor device fabrication technology and bottom-gate polycrystalline-silicon thin-film transistors. He is currently pursuing the integrated M.S and Ph.D course with the Department of Materials Science and Engineering, Seoul National University, Seoul. He is involved in semiconductor device fabrication technology and copper

  13. Improvement of the thermal stability of nickel silicide using a ruthenium interlayer deposited via remote plasma atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Inhye [Department of Materials Science and Engineering, Hanyang University, Seoul 04763, South Korea and System LSI Manufacturing Operation Center, Samsung Electronics Co., Ltd, Gyeonggi-do 17113 (Korea, Republic of); Park, Jingyu; Jeon, Heeyoung; Kim, Hyunjung; Shin, Changhee [Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 04763 (Korea, Republic of); Shin, Seokyoon; Lee, Kunyoung [Department of Materials Science and Engineering, Hanyang University, Seoul 04763 (Korea, Republic of); Jeon, Hyeongtag, E-mail: [Department of Materials Science and Engineering, Hanyang University, Seoul 04763, South Korea and Department of Nano-scale Semiconductor Engineering, Hanyang University, Seoul 04763 (Korea, Republic of)


    In this study, the effects of a thin Ru interlayer on the thermal and morphological stability of NiSi have been investigated. Ru and Ni thin films were deposited sequentially to form a Ni/Ru/Si bilayered structure, without breaking the vacuum, by remote plasma atomic layer deposition (RPALD) on a p-type Si wafer. After annealing at various temperatures, the thermal stabilities of the Ni/Ru/Si and Ni/Si structures were investigated by various analysis techniques. The results showed that the sheet resistance of the Ni/Ru/Si sample was consistently lower compared to the Ni/Si sample over the entire temperature range. Although both samples exhibited the formation of NiSi{sub 2} phases at an annealing temperature of 800 °C, as seen with glancing angle x-ray diffraction, the peaks of the Ni/Ru/Si sample were observed to have much weaker intensities than those obtained for the Ni/Si sample. Moreover, the NiSi film with a Ru interlayer exhibited a better interface and improved surface morphologies compared to the NiSi film without a Ru interlayer. These results show that the phase transformation of NiSi to NiSi{sub 2} was retarded and that the smooth NiSi/Si interface was retained due to the activation energy increment for NiSi{sub 2} nucleation that is caused by adding a Ru interlayer. Hence, it can be said that the Ru interlayer deposited by RPALD can be used to control the phase transformation and physical properties of nickel silicide phases.

  14. Behavior of a VVER fuel element tested under severe accident conditions in the CORA facility. Test results of experiment CORA-W1

    Energy Technology Data Exchange (ETDEWEB)

    Hagen, S.; Hofmann, P.; Noack, V.; Schanz, G.; Schumacher, G.; Sepold, L.


    Test bundle CORA-W1 was without absorber material. As in the earlier CORA tests the test bundles were subjected to temperature transients of a slow heatup rate in a steam environment. The transient phases of the test were initiated with a temperature ramp rate of 1 K/s. With these conditions a so-called small-break LOCA was simulated. The temperature escalation due to the exothermal zirconium/niobium-steam reaction started at about 1200 C, leading the bundle to a maximum temperature of approximately 1900 C. With the movement of the melt also heat is transported to the lower region. Below 300 mm elevation the test bundle remained intact due to the axial temeprature distribution. W2 ist characterized by a strong oxidation above 300 mm elevation. Besides the severe oxidation the test bundle resulted in considerable fuel dissolution by ZrNb1/UO{sub 2} interaction in the upper part, complete spacer destruction at 600 mm due to chemical interactions between steel and the ZSrNb1 cladding. Despite some specific features the material behavior of the VVER-1000 bundle is comparable to that observed in the PWR and BWR test using fuel elements typical for Western countries. (orig./HP) [Deutsch] Versuchsbuendel CORA-W1 hatte kein Absorberelement. Wie in den CORA-Versuchen zuvor wurden die Testbuendel in Dampfatmosphaere Temperaturtransienten mit langsamer Aufheizrate ausgesetzt. Damit wurde ein Unfallablauf fuer einen LWR simuliert, der sich aus einem Kuehlmittelverluststoerfall durch Auftreten eines sogenannten kleinen Lecks entwickeln kann. Die Temperatureskalation - aufgrund der exothermen Zirkon/Niob-Wasserdampfreaktion - setzte ab ca. 1100 C ein. Die Hoechsttemperaturen im Buendel betrugen 2000 C. Die Versuchsdaten des Experiments CORA-W1 werden zusammen mit ersten Ergebnissen der Nachuntersuchung dargelegt. Das Versuchsbuendel weist eine starke Oxidation im oberen Bereich auf. Der untere Buendelabschnitt (bis 400 mm) blieb aufgrund der niedrigen Temperaturen in diesem

  15. Fossil Fuels. (United States)

    Crank, Ron

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with fossil fuels. Some topics covered are historic facts, development of fuels, history of oil production, current and future trends of the oil industry, refining fossil fuels, and environmental problems. Material in each unit may…

  16. Loading rate and test temperature effects on fracture of In Situ niobium silicide-niobium composites (United States)

    Rigney, Joseph D.; Lewandowski, John J.


    Arc cast, extruded, and heat-treated in situ composites of niobium suicide (Nb5Si3) intermetallic with niobium phases (primary—Nbp and secondary—Nbs) exhibited high fracture resistance in comparison to monolithic Nb5Si3. In toughness tests conducted at 298 K and slow applied loading rates, the fracture process proceeded by the microcracking of the Nb5Si3 and plastic deformation of the Nbp and Nbs phases, producing resistance-curve behavior and toughnesses of 28 MPa√m with damage zone lengths less than 500 μm. The effects of changes in the Nbp yield strength and fracture behavior on the measured toughnesses were investigated by varying the loading rates during fracture tests at both 77 and 298 K. Quantitative fractography was utilized to completely characterize each fracture surface created at 298 K in order to determine the type of fracture mode ( i.e., dimpled, cleavage) exhibited by the Nbp. Specimens tested at either higher loading rates or lower test temperatures consistently exhibited a greater amount of cleavage fracture in the Nbp, while the Nbs, always remained ductile. However, the fracture toughness values determined from experiments spanning six orders of magnitude in loading rate at 298 and 77 K exhibited little variation, even under conditions when the majority of Nbp phases failed by cleavage at 77 K. The changes in fracture mode with increasing loading rate and/or decreasing test temperature and their effects on fracture toughness are rationalized by comparison to existing theoretical models.

  17. Alternative fuels and vehicles choice model

    Energy Technology Data Exchange (ETDEWEB)

    Greene, D.L. [Oak Ridge National Lab., TN (United States). Center for Transportation Analysis


    This report describes the theory and implementation of a model of alternative fuel and vehicle choice (AFVC), designed for use with the US Department of Energy`s Alternative Fuels Trade Model (AFTM). The AFTM is a static equilibrium model of the world supply and demand for liquid fuels, encompassing resource production, conversion processes, transportation, and consumption. The AFTM also includes fuel-switching behavior by incorporating multinomial logit-type equations for choice of alternative fuel vehicles and alternative fuels. This allows the model to solve for market shares of vehicles and fuels, as well as for fuel prices and quantities. The AFVC model includes fuel-flexible, bi-fuel, and dedicated fuel vehicles. For multi-fuel vehicles, the choice of fuel is subsumed within the vehicle choice framework, resulting in a nested multinomial logit design. The nesting is shown to be required by the different price elasticities of fuel and vehicle choice. A unique feature of the AFVC is that its parameters are derived directly from the characteristics of alternative fuels and vehicle technologies, together with a few key assumptions about consumer behavior. This not only establishes a direct link between assumptions and model predictions, but facilitates sensitivity testing, as well. The implementation of the AFVC model as a spreadsheet is also described.

  18. Carrier-transport mechanism of Er-silicide Schottky contacts to strained-silicon-on-insulator and silicon-on-insulator. (United States)

    Jyothi, I; Janardhanam, V; Kang, Min-Sung; Yun, Hyung-Joong; Lee, Jouhahn; Choi, Chel-Jong


    The current-voltage characteristics and the carrier-transport mechanism of the Er-silicide (ErSi1.7) Schottky contacts to strained-silicon-on-insulator (sSOI) and silicon-on-insulator (SOI) were investigated. Barrier heights of 0.74 eV and 0.82 eV were obtained for the sSOI and SOI structures, respectively. The barrier height of the sSOI structure was observed to be lower than that of the SoI structure despite the formation of a Schottky contact using the same metal silicide. The sSOI structure exhibited better rectification and higher current level than the SOI structure, which could be associated with a reduction in the band gap of Si caused by strain. The generation-recombination mechanism was found to be dominant in the forward bias for both structures. Carrier generation along with the Poole-Frenkel mechanism dominated the reverse-biased current in the SOI structure. The saturation tendency of the reverse leakage current in the sSOI structure could be attributed to strain-induced defects at the interface in non-lattice-matched structures.

  19. 45Sc Solid State NMR studies of the silicides Sc TSi ( T=Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) (United States)

    Harmening, Thomas; Eckert, Hellmut; Fehse, Constanze M.; Sebastian, C. Peter; Pöttgen, Rainer


    The silicides Sc TSi ( T=Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) were synthesized by arc-melting and characterized by X-ray powder diffraction. The structures of ScCoSi, ScRuSi, ScPdSi, and ScIrSi were refined from single crystal diffractometer data. These silicides crystallize with the TiNiSi type, space group Pnma. No systematic influences of the 45Sc isotropic magnetic shift and nuclear electric quadrupolar coupling parameters on various structural distortion parameters calculated from the crystal structure data can be detected. 45Sc MAS-NMR data suggest systematic trends in the local electronic structure probed by the scandium atoms: both the electric field gradients and the isotropic magnetic shifts relative to a 0.2 M aqueous Sc(NO 3) 3 solution decrease with increasing valence electron concentration and within each T group the isotropic magnetic shift decreases monotonically with increasing atomic number. The 45Sc nuclear electric quadrupolar coupling constants are generally well reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code.

  20. Synthesis of nano-patterned and Nickel Silicide embedded amorphous Si thin layer by ion implantation for higher efficiency solar devices (United States)

    Bhowmik, D.; Bhattacharjee, S.; Lavanyakumar, D.; Naik, V.; Satpati, B.; Karmakar, P.


    We report the ion beam based single step synthesis process of surface-patterned amorphous Silicon (a-Si) with a buried plasmon active nickel silicide layer for the realization of cost-effective, higher efficiency Silicon (Si) photovoltaic devices. Simultaneous amorphization, surface pattern formation and buried layer development are achieved by normal incidence 10 keV Ni1+ ion bombardment on Si(100) surface at a fluence of 1 × 1017. Atomic Force Microscopy study shows rim-surrounded crater like periodic nanostructure on the surface whereas cross-sectional Transmission Electron Microscopy detects the amorphization and implant buried layer just below the surface. The distribution of implanted Ni ions and Si vacancies, obtained by the Monte Carlo simulation (SRIM) is consistent with the experimental results. Spatially resolved Electron Energy Loss Spectroscopy measurement detects that the buried layer is nickel silicide. The potential application of such nano-patterned and plasmon active system for future low-cost a-Si based higher efficient Photovoltaic devices is discussed.

  1. Fuel distribution

    Energy Technology Data Exchange (ETDEWEB)

    Tison, R.R.; Baker, N.R.; Blazek, C.F.


    Distribution of fuel is considered from a supply point to the secondary conversion sites and ultimate end users. All distribution is intracity with the maximum distance between the supply point and end-use site generally considered to be 15 mi. The fuels discussed are: coal or coal-like solids, methanol, No. 2 fuel oil, No. 6 fuel oil, high-Btu gas, medium-Btu gas, and low-Btu gas. Although the fuel state, i.e., gas, liquid, etc., can have a major impact on the distribution system, the source of these fuels (e.g., naturally-occurring or coal-derived) does not. Single-source, single-termination point and single-source, multi-termination point systems for liquid, gaseous, and solid fuel distribution are considered. Transport modes and the fuels associated with each mode are: by truck - coal, methanol, No. 2 fuel oil, and No. 6 fuel oil; and by pipeline - coal, methane, No. 2 fuel oil, No. 6 oil, high-Btu gas, medium-Btu gas, and low-Btu gas. Data provided for each distribution system include component makeup and initial costs.

  2. Thermoelectric characteristics of iron silicide thermoelectric converter with the transition metallic compound as an additive; Sen`i kinzoku kagobutsu wo tenkabutsu to shita keikatetsu netsuden soshi no netsuden tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Hayashibara, M.; Oda, M. [Hitachi, Ltd., Tokyo (Japan)


    The thin film must be converted into a bulky shape in order that the high electric power may be produced by the iron silicide thermoelectric converter. Study was then made to establish the homogeneous bulk production method, in which the additive must diffuse sufficiently in the iron silicide and bond strongly to it during the sintering. Selected as an additive in the present study, Co compounds were all decomposed below the sintering temperature and remained in the iron silicide. The Co sulfide, phosphide, bromide and iodide were particularly high in reactivity with the iron silicide. The Co, of which the added quantity was proportional to the electric conductivity, was almost homogenized into a solid solution. In the experiment, both Co sulfide and phosphide were equal in thermoelectric power as an additive. The Co bromide and iodide were maximally about 10% and 50%, respectively lower in thermoelectric power than the Co sulfide. It is attributable to the FeSi2 reformed to the electrically insulating SiO2 and low-thermoelectric power FeSi, because both Co bromide and iodide are oxidizing compounds. 7 refs., 10 figs.

  3. Synthesis on the long term behavior of spent nuclear fuel. Vol.1,2; Synthese sur l'evolution a long terme des colis de combustibles irradies. Tome 1,2

    Energy Technology Data Exchange (ETDEWEB)

    Poinssot, Ch.; Toulhoat, P.; Grouiller, J.P.; Pavageau, J.; Piron, J.P.; Pelletier, M.; Dehaudt, Ph.; Cappelaere, Ch.; Limon, R.; Desgranges, L.; Jegou, Ch.; Corbel, C.; Maillard, S.; Faure, M.H.; Cicariello, J.C.; Masson, M. [CEA Saclay, DEN/DDIN/DPRGD, 91 - Gif sur Yvette (France)


    The aim of this report is to present the major objectives, the key scientific issues, and the preliminary results of the research conducted in France in the framework of the third line of the 1991 Law, on the topic of the long term behavior of spent nuclear fuel in view of long term storage or geological disposal. Indeed, CEA launched in 1998 the Research Program on the Long Term Behavior of Spent Nuclear Fuel (abbreviated and referred to as PRECCI in French; Poinssot, 1998) the aim of which is to study and assess the ability of spent nuclear fuel packages to keep their initially allocated functions in interim storage and geological disposal: total containment and recovery functions for duration up to hundreds of years (long term or short-term interim storage and/or first reversible stages of geological disposal) and partial confinement function (controlled fluxes of RN) for thousands of years in geological disposal. This program has to allow to obtain relevant and reliable data concerning the long term behavior of the spent fuel packages so that feasibility of interim storage and/or geological disposal can be assessed and demonstrated as well as optimized. Within this framework, this report presents for every possible scenario of evolution (closed system, in Presence of water in presence of gases) what are estimated to be the most relevant evolution mechanism. For the most relevant scientific issues hence defined, a complete scientific review of the best state of knowledge is subsequently here given thus allowing to draw a clear guideline of the major R and D issues for the next years. (authors)

  4. Modeling fuels and fire effects in 3D: Model description and applications (United States)

    Francois Pimont; Russell Parsons; Eric Rigolot; Francois de Coligny; Jean-Luc Dupuy; Philippe Dreyfus; Rodman R. Linn


    Scientists and managers critically need ways to assess how fuel treatments alter fire behavior, yet few tools currently exist for this purpose.We present a spatially-explicit-fuel-modeling system, FuelManager, which models fuels, vegetation growth, fire behavior (using a physics-based model, FIRETEC), and fire effects. FuelManager's flexible approach facilitates...

  5. Liquid phase behavior in an emulsified fuel droplet burning under microgravity; Bisho juryoku ka nyuka nenryo ekiteki nenshoji ni okeru ekisono kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Segawa, D.; Tanaka, H.; Hoshito, K.; Kadota, T. [University of Osaka Prefecture, Osaka (Japan); Yamasaki, H. [Ehime Univ., Ehime (Japan). Faculty of Education


    An experimental study has been carried out to obtain the detailed information needed for the deep understanding of the combustion process of an emulsified fuel droplet under microgravity. The experiments were conducted by using the drop shaft of JAMIC (Japan Microgravity Center) at Hokkaido. Photographic observation and temperature measurement were made of the emulsified fuel droplet burning in quiescent gaseous environment at the atmospheric pressure. The primary attention was toward the transport processes in the liquid phase and the time histories of liquid temperature and the amount of water in the liquid phase during the period of time prior to the microexplosion. The results showed that the agglomeration and separation of the water and the base fuel layers occurred with the lapse of time. The increase in the temperature of the emulsified fuel resulted in the formation of a single water droplet enveloped by a shell of base fuel prior to the microexplosion. After the phase separation, selective evaporation of the base fuel would occur and the volume of base fuel decreased while the water volume did not change. The effects of the water volume on the onset rate of microexplosion were also revealed. (author)

  6. Characterization of complex carbide–silicide precipitates in a Ni–Cr–Mo–Fe–Si alloy modified by welding

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharyya, D., E-mail:; Davis, J.; Drew, M.; Harrison, R.P.; Edwards, L.


    Nickel based alloys of the type Hastelloy-N™ are ideal candidate materials for molten salt reactors, as well as for applications such as pressure vessels, due to their excellent resistance to creep, oxidation and corrosion. In this work, the authors have attempted to understand the effects of welding on the morphology, chemistry and crystal structure of the precipitates in the heat affected zone (HAZ) and the weld zone of a Ni–Cr–Mo–Fe–Si alloy similar to Hastelloy-N™ in composition, by using characterization techniques such as scanning and transmission electron microscopy. Two plates of a Ni–Cr–Mo–Fe–Si alloy GH-3535 were welded together using a TiG welding process without filler material to achieve a joint with a curved molten zone with dendritic structure. It is evident that the primary precipitates have melted in the HAZ and re-solidified in a eutectic-like morphology, with a chemistry and crystal structure only slightly different from the pre-existing precipitates, while the surrounding matrix grains remained unmelted, except for the zones immediately adjacent to the precipitates. In the molten zone, the primary precipitates were fully melted and dissolved in the matrix, and there was enrichment of Mo and Si in the dendrite boundaries after solidification, and re-precipitation of the complex carbides/silicides at some grain boundaries and triple points. The nature of the precipitates in the molten zone varied according to the local chemical composition. - Graphical abstract: Display Omitted - Highlights: • Ni-based alloy with Cr, Mo, Si, Fe and C was welded, examined with SEM, EBSD, and TEM. • Original Ni{sub 2}(Mo,Cr){sub 4}(Si,C) carbides changed from equiaxed to lamellar shape in HAZ. • Composition and crystal structure remained almost unchanged in HAZ. • Original carbides changed to lamellar Ni{sub 3}(Mo,Cr){sub 3}(Si,C) in some cases in weld metal. • Precipitates were mostly incoherent, but semi-coherent in some cases in weld

  7. Effect of Fuel Composition on Vaporization Behavior in Gasoline Engines--Analyzing In-cylinder Gas Composition by High Speed Gas Sampling System

    National Research Council Canada - National Science Library

    Koji Oyama; Gen Shibata; Seiichi Nakano; Tohru Isoda


      To investigate the effect of fuel composition on mixture formation in the intake port-injection gasoline engine, engine tests with in-cylinder gas sampling were conducted using 10 types of model...

  8. Fuel Cells

    DEFF Research Database (Denmark)

    Smith, Anders; Pedersen, Allan Schrøder


    Fuel cells have been the subject of intense research and development efforts for the past decades. Even so, the technology has not had its commercial breakthrough yet. This entry gives an overview of the technological challenges and status of fuel cells and discusses the most promising applications...... of the different types of fuel cells. Finally, their role in a future energy supply with a large share of fluctuating sustainable power sources, e.g., solar or wind, is surveyed....

  9. Dry process fuel performance technology development

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Kweon Ho; Kim, K. W.; Kim, B. K. (and others)


    The objective of the project is to establish the performance evaluation system of DUPIC fuel during the Phase III R and D. In order to fulfil this objectives, property model development of DUPIC fuel and irradiation test was carried out in Hanaro using the instrumented rig. Also, the analysis on the in-reactor behavior analysis of DUPIC fuel, out-pile test using simulated DUPIC fuel as well as performance and integrity assessment in a commercial reactor were performed during this Phase. The R and D results of the Phase III are summarized as follows: Fabrication process establishment of simulated DUPIC fuel for property measurement, Property model development for the DUPIC fuel, Performance evaluation of DUPIC fuel via irradiation test in Hanaro, Post irradiation examination of irradiated fuel and performance analysis, Development of DUPIC fuel performance code (KAOS)

  10. Nuclear Energy Advanced Modeling and Simulation (NEAMS) Accident Tolerant Fuels High Impact Problem: Coordinate Multiscale U3Si2 Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, K. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hales, J. D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miao, Y. [Argonne National Lab. (ANL), Argonne, IL (United States); Andersson, D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Since the events at the Fukushima-Daiichi nuclear power plant in March 2011 significant research has unfolded at national laboratories, universities and other institutions into alternative materials that have potential enhanced accident tolerance when compared to traditional \\uo~fuel zircaloy clad fuel rods. One of the potential replacement fuels is uranium silicide (\\usi) for its higher thermal conductivity and uranium density. The lower melting temperature is of potential concern during postulated accident conditions. Another disadvantage for \\usi~ is the lack of experimental data under power reactor conditions. Due to the aggressive development schedule for inserting some of the potential materials into lead test assemblies or rods by 2022~\\cite{bragg-sitton_2014} multiscale multiphysics modeling approaches have been used to provide insight into these materials. \\\\ \

  11. Fuel cells:

    DEFF Research Database (Denmark)

    Sørensen, Bent


    A brief overview of the progress in fuel cell applications and basic technology development is presented, as a backdrop for discussing readiness for penetration into the marketplace as a solution to problems of depletion, safety, climate or environmental impact from currently used fossil...... and nuclear fuel-based energy technologies....

  12. Studies of behavior of the fuel compound based on the U-Zr micro-heterogeneous quasialloy during cyclic thermal tests (United States)

    Zaytsev, D. A.; Repnikov, V. M.; Soldatkin, D. M.; Solntsev, V. A.


    This paper provides the description of temperature cycle testing of U-Zr heterogeneous fuel composition. The composition is essentially a niobium-doped zirconium matrix with metallic uranium filaments evenly distributed over the cross section. The test samples 150 mm long had been fabricated using a fiber-filament technology. The samples were essentially two-bladed spiral mandrel fuel elements parts. In the course of experiments the following temperatures were applied: 350, 675, 780 and 1140 °C with total exposure periods equal to 200, 30, 30 and 6 hours respectively. The fuel element samples underwent post-exposure material science examination including: geometry measurements, metallographic analysis, X-ray phase analysis and electron-microscopic analysis as well as micro-hardness measurement. It has been found that no significant thermal swelling of the samples occurs throughout the whole temperature range from 350 °C up to 1140 °C. The paper presents the structural changes and redistribution of the fuel component over the fuel element cross section with rising temperature.

  13. Use of alternative fuels in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)



    A future sustainable energy system will certainly be based on a variety of environmentally benign energy production technologies. Fuel cells can be a key element in this scenario. One of the fuel cells types the solid oxide fuel cell (SOFC) has a number of advantages that places them in a favorable position: high efficiency, parallel production of electricity and high value heat, prevention of NOx emission, flexibility regarding usable fuels, and certain tolerance towards impurities. It is thus a natural option, to combine such a highly efficient energy conversion tool with a sustainable fuel supply. In the present contribution, the use of alternative compared to conventional fuels in SOFCs was evaluated. Regarding carbon containing, biomass derived fuels, SOFCs showed excellent power output and stability behavior during long-term testing under technologically relevant conditions. Moreover, ammonia can be used directly as fuel. The chemical and structural properties of the SOFC anode makes it even possible, to combine a chemical conversion of the fuel, for example methane into synthesis gas via steam reforming and decomposition of ammonia into hydrogen and nitrogen, with the electrochemical production of electricity in one step. (au)

  14. Reprocessing of research reactor fuel the Dounreay option

    Energy Technology Data Exchange (ETDEWEB)

    Cartwright, P.


    Reprocessing is a proven process for the treatment of spent U/Al Research Reactor fuel. At Dounreay 12679 elements have been reprocessed during the past 30 years. For reactors converting to LEU fuel the uranium recovered in reprocessing can be blended down to less than 20% U{sub 235}, enrichment and be fabricated into new elements. For reactors already converted to LEU it is technically possible to reprocess spent silicide fuel to reduce the U{sub 235} burden and present to a repository only stable conditioned waste. The main waste stream from reprocessing which contains the Fission products is collected in underground storage tanks where it is kept for a period of at least five years before being converted to a stable solid form for return to the country of origin for subsequent storage/disposal. Discharges to the environment from reprocessing are low and are limited to the radioactive gases contained in the spent fuel and a low level liquid waste steam. Both of these discharges are independently monitored, and controlled within strict discharge limits set by the UK Government`s Scottish Office. Transportation of spent fuel to Dounreay has been undertaken using many routes from mainland Europe and has utilised over the past few years both chartered and scheduled vessel services. Several different transport containers have been handled and are currently licensed in the UK. This paper provides a short history of MTR reprocessing at Dounreay, and provides information to show reprocessing can satisfy the needs of MTR operators, showing that reprocessing is a valuable asset in non-proliferation terms, offers a complete solution and is environmentally acceptable.

  15. Advanced thermally stable jet fuels

    Energy Technology Data Exchange (ETDEWEB)

    Schobert, H.H.


    The Pennsylvania State University program in advanced thermally stable coal-based jet fuels has five broad objectives: (1) Development of mechanisms of degradation and solids formation; (2) Quantitative measurement of growth of sub-micrometer and micrometer-sized particles suspended in fuels during thermal stressing; (3) Characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) Elucidation of the role of additives in retarding the formation of carbonaceous solids; (5) Assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Future high-Mach aircraft will place severe thermal demands on jet fuels, requiring the development of novel, hybrid fuel mixtures capable of withstanding temperatures in the range of 400--500 C. In the new aircraft, jet fuel will serve as both an energy source and a heat sink for cooling the airframe, engine, and system components. The ultimate development of such advanced fuels requires a thorough understanding of the thermal decomposition behavior of jet fuels under supercritical conditions. Considering that jet fuels consist of hundreds of compounds, this task must begin with a study of the thermal degradation behavior of select model compounds under supercritical conditions. The research performed by The Pennsylvania State University was focused on five major tasks that reflect the objectives stated above: Task 1: Investigation of the Quantitative Degradation of Fuels; Task 2: Investigation of Incipient Deposition; Task 3: Characterization of Solid Gums, Sediments, and Carbonaceous Deposits; Task 4: Coal-Based Fuel Stabilization Studies; and Task 5: Exploratory Studies on the Direct Conversion of Coal to High Quality Jet Fuels. The major findings of each of these tasks are presented in this executive summary. A description of the sub-tasks performed under each of these tasks and the findings of those studies are provided in the remainder of this volume

  16. Evaluating the performance and mapping of three fuel classification systems using Forest Inventory and Analysis surface fuel measurements (United States)

    Robert E. Keane; Jason M. Herynk; Chris Toney; Shawn P. Urbanski; Duncan C. Lutes; Roger D. Ottmar


    Fuel Loading Models (FLMs) and Fuel Characteristic Classification System (FCCSs) fuelbeds are used throughout wildland fire science and management to simplify fuel inputs into fire behavior and effects models, but they have yet to be thoroughly evaluated with field data. In this study, we used a large dataset of Forest Inventory and Analysis (FIA) surface fuel...

  17. ArcFuels: an ArcMap toolbar for fuel treatment planning and wildfire risk assessment (United States)

    Nicole M. Vaillant; Alan A. Ager


    Fire behavior modeling and geospatial analysis can provide tremendous insight to land managers in defining both the benefits and potential impacts of fuel treatments in the context of land management goals and public expectations. ArcFuels is a streamlined fuel management planning and wildfire risk assessment system that creates a trans-scale (stand to large landscape...

  18. Fuel cell-fuel cell hybrid system (United States)

    Geisbrecht, Rodney A.; Williams, Mark C.


    A device for converting chemical energy to electricity is provided, the device comprising a high temperature fuel cell with the ability for partially oxidizing and completely reforming fuel, and a low temperature fuel cell juxtaposed to said high temperature fuel cell so as to utilize remaining reformed fuel from the high temperature fuel cell. Also provided is a method for producing electricity comprising directing fuel to a first fuel cell, completely oxidizing a first portion of the fuel and partially oxidizing a second portion of the fuel, directing the second fuel portion to a second fuel cell, allowing the first fuel cell to utilize the first portion of the fuel to produce electricity; and allowing the second fuel cell to utilize the second portion of the fuel to produce electricity.

  19. Evaluation of MHD materials for use in high-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Guidotti, R.


    The MHD and high-temperature fuel cell literature was surveyed for data pertaining to materials properties in order to identify materials used in MHD power generation which also might be suitable for component use in high-temperature fuel cells. Classes of MHD-electrode materials evaluated include carbides, nitrides, silicides, borides, composites, and oxides. Y/sub 2/O/sub 3/-stabilized ZrO/sub 2/ used as a reference point to evaluate materials for use in the solid-oxide fuel cell. Physical and chemical properties such as electrical resistivity, coefficient of thermal expansion, and thermodynamic stability toward oxidation were used to screen candidate materials. A number of the non-oxide ceramic MHD-electrode materials appear promising for use in the solid-electrolyte and molten-carbonate fuel cell as anodes or anode constituents. The MHD-insulator materials appear suitable candidates for electrolyte-support tiles in the molten-carbonate fuel cells. The merits and possible problem areas for these applications are discussed and additional needed areas of research are delineated.

  20. Analysis on the dynamic behavior of corrosion products in the nuclear fuel of a PWR and itsrelationship with the Axial Offset Anomaly (AOA)risk using BOA calculation code


    Sarria Morales, Marina


    This master’s thesis can be characterized as a research project about nuclear engineering. The object of this thesis is the primary system of Vandellós II nuclear power plant. Specifically, it has been focused on the dynamic behavior of corrosion products in the nuclear fuel of a nuclear core Vandellós II PWR. The report describes the operation of the Reactor Coolant System (RCS), highlighting and making a detailed study of an existing and common problem in different nuclear plants a...

  1. Silicides for VLSI applications

    CERN Document Server

    Murarka, Shyam P


    Most of the subject matter of this book has previously been available only in the form of research papers and review articles. I have not attempted to refer to all the published papers. The reader may find it advantageous to refer to the references listed.

  2. Effects of dormant and growing season burning on surface fuels and potential fire behavior in northern Florida longleaf pine (Pinus palustris) flatwoods (United States)

    James B. Cronan; Clinton S. Wright; Maria Petrova


    Prescribed fire is widely used to manage fuels in high-frequency, low-severity fire regimes including pine flatwoods of the southeastern USA where prescribed burning during the growing season (the frost-free period during the calendar year) has become more common in recent decades. Growing season prescribed fires address ecological management objectives that focus on...

  3. Application of game theory in decision making strategy: Does gas fuel industry need to kill oil based fuel industry? (United States)

    Azmi, Abdul Luky Shofi'ul; Prabandari, Dyah Lusiana; Hakim, Muhammad Lintang Islami


    Even though conversion of oil based fuel (Bahan Bakar Minyak) into gas fuel (Bahan Bakar Gas) for transportation (both land and sea) is one of the priority programs of the government of Indonesia, rules that have been established merely basic rules of gas fuel usage license for transportation, without discussing position of gas fuel related to oil based fuel in detail. This paper focus on possible strategic behavior of the key players in the oil-gas fuel conversion game, who will be impacted by the position of gas fuel as complement or substitution of oil based fuel. These players include industry of oil based fuel, industry of gas fuel, and the government. Modeling is made based on two different conditions: government plays a passive role and government plays an active role in legislating additional rules that may benefit industry of gas fuel. Results obtained under a passive government is that industry of oil based fuel need to accommodate the presence of industry of gas fuel, and industry of gas fuel does not kill/ eliminate the oil based fuel, or gas fuel serves as a complement. While in an active government, the industry of oil based fuel need to increase its negotiation spending in the first phase so that the additional rule that benefitting industry of gas fuel would not be legislated, while industry of gas fuel chooses to indifferent; however, in the last stage, gas fuel turned to be competitive or choose its role to be substitution.

  4. Proceedings of the Water Reactor Fuel Performance Meeting - WRFPM / Top Fuel 2009

    Energy Technology Data Exchange (ETDEWEB)



    SFEN, ENS, SNR, ANS, AESJ, CNS KNS, IAEA and NEA are jointly organizing the 2009 International Water Reactor Fuel Performance / TopFuel 2009 Meeting following the 2008 KNS Water Reactor Performance Meeting held during October 19-23, 2008 in Seoul, Korea. This meeting is held annually on a tri-annual rotational basis in Europe, USA and Asia. In 2009, this meeting will be held in Paris, September 6-10, 2009 in coordination with the Global 2009 Conference at the same date and place. That would lead to a common opening session, some common technical presentations, a common exhibition and common social events. The technical scope of the meeting includes all aspects of nuclear fuel from fuel rod to core design as well as manufacturing, performance in commercial and test reactors or on-going and future developments and trends. Emphasis will be placed on fuel reliability in the general context of nuclear 'Renaissance' and recycling perspective. The meeting includes selectively front and/or back end issues that impact fuel designs and performance. In this frame, the conference track devoted to 'Concepts for transportation and interim storage of spent fuels and conditioned waste' will be shared with 'GLOBAL' conference. Technical Tracks: - 1. Fuel Performance, Reliability and Operational Experience: Fuel operating experience and performance; experience with high burn-up fuels; water side corrosion; stress corrosion cracking; MOX fuel performance; post irradiation data on lead fuel assemblies; radiation effects; water chemistry and corrosion counter-measures. - 2. Transient Fuel Behaviour and Safety Related Issues: Transient fuel behavior and criteria (RIA, LOCA, ATWS, Ramp tests..). Fuel safety-related issues such as PCI (pellet cladding interaction), transient fission gas releases and cladding bursting/ballooning during transient events - Advances in fuel performance modeling and core reload methodology, small and large-scale fuel testing

  5. Evaluation of MHTGR fuel reliability

    Energy Technology Data Exchange (ETDEWEB)

    Wichner, R.P. [Oak Ridge National Lab., TN (United States); Barthold, W.P. [Barthold Associates, Inc., Knoxville, TN (United States)


    Modular High-Temperature Gas-Cooled Reactor (MHTGR) concepts that house the reactor vessel in a tight but unsealed reactor building place heightened importance on the reliability of the fuel particle coatings as fission product barriers. Though accident consequence analyses continue to show favorable results, the increased dependence on one type of barrier, in addition to a number of other factors, has caused the Nuclear Regulatory Commission (NRC) to consider conservative assumptions regarding fuel behavior. For this purpose, the concept termed ``weak fuel`` has been proposed on an interim basis. ``Weak fuel`` is a penalty imposed on consequence analyses whereby the fuel is assumed to respond less favorably to environmental conditions than predicted by behavioral models. The rationale for adopting this penalty, as well as conditions that would permit its reduction or elimination, are examined in this report. The evaluation includes an examination of possible fuel-manufacturing defects, quality-control procedures for defect detection, and the mechanisms by which fuel defects may lead to failure.

  6. FPIN2 analysis of metal fueled pins

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, T H


    The FPIN2 code is used to calculate the thermal and mechanical behavior of a single fast reactor fuel pin experiencing a wide range of transients. This report describes the modifications and additions made to the FPIN2 code in order to handle metal fueled pins. The changes discussed in this status report have initially focused upon EBR-II driver fuel in order to calculate the temperature histories of EBR-II fuel and to understand the detailed behavior of metal fuel during recent TREAT experiments. Equations describing material behavior of metal fuel including thermal properties, elastic properties, secondary creep and fission gas swelling are presented and were easily incorporated into the FPIN2 code framework. The addition of a fission gas plenum model and a model to close the fuel-clad radial gap at 100% fuel melting required substantial modification to the code. Additional changes were made to handle heat transfer with a sodium bond, eutectic release of cladding axial restraint and eutectic penetration of the cladding. Three example calculations are presented including a study of the effect of fuel creep on axial elongation and temperature contour maps for EBR-II driver fuel. Some results from an FPIN2 analysis of TREAT experiment M2 are discussed.


    Directory of Open Access Journals (Sweden)

    M.K. MEYER


    Full Text Available High-performance research reactors require fuel that operates at high specific power to high fission density, but at relatively low temperatures. Research reactor fuels are designed for efficient heat rejection, and are composed of assemblies of thin-plates clad in aluminum alloy. The development of low-enriched fuels to replace high-enriched fuels for these reactors requires a substantially increased uranium density in the fuel to offset the decrease in enrichment. Very few fuel phases have been identified that have the required combination of very-high uranium density and stable fuel behavior at high burnup. UMo alloys represent the best known tradeoff in these properties. Testing of aluminum matrix U-Mo aluminum matrix dispersion fuel revealed a pattern of breakaway swelling behavior at intermediate burnup, related to the formation of a molybdenum stabilized high aluminum intermetallic phase that forms during irradiation. In the case of monolithic fuel, this issue was addressed by eliminating, as much as possible, the interfacial area between U-Mo and aluminum. Based on scoping irradiation test data, a fuel plate system composed of solid U-10Mo fuel meat, a zirconium diffusion barrier, and Al6061 cladding was selected for development. Developmental testing of this fuel system indicates that it meets core criteria for fuel qualification, including stable and predictable swelling behavior, mechanical integrity to high burnup, and geometric stability. In addition, the fuel exhibits robust behavior during power-cooling mismatch events under irradiation at high power.

  8. Reforming of fuel inside fuel cell generator (United States)

    Grimble, Ralph E.


    Disclosed is an improved method of reforming a gaseous reformable fuel within a solid oxide fuel cell generator, wherein the solid oxide fuel cell generator has a plurality of individual fuel cells in a refractory container, the fuel cells generating a partially spent fuel stream and a partially spent oxidant stream. The partially spent fuel stream is divided into two streams, spent fuel stream I and spent fuel stream II. Spent fuel stream I is burned with the partially spent oxidant stream inside the refractory container to produce an exhaust stream. The exhaust stream is divided into two streams, exhaust stream I and exhaust stream II, and exhaust stream I is vented. Exhaust stream II is mixed with spent fuel stream II to form a recycle stream. The recycle stream is mixed with the gaseous reformable fuel within the refractory container to form a fuel stream which is supplied to the fuel cells. Also disclosed is an improved apparatus which permits the reforming of a reformable gaseous fuel within such a solid oxide fuel cell generator. The apparatus comprises a mixing chamber within the refractory container, means for diverting a portion of the partially spent fuel stream to the mixing chamber, means for diverting a portion of exhaust gas to the mixing chamber where it is mixed with the portion of the partially spent fuel stream to form a recycle stream, means for injecting the reformable gaseous fuel into the recycle stream, and means for circulating the recycle stream back to the fuel cells.

  9. Final Report on the Fuel Saving Effectiveness of Various Driver Feedback Approaches

    Energy Technology Data Exchange (ETDEWEB)

    Gonder, J.; Earleywine, M.; Sparks, W.


    This final report quantifies the fuel-savings opportunities from specific driving behavior changes, identifies factors that influence drivers' receptiveness to adopting fuel-saving behaviors, and assesses various driver feedback approaches.

  10. Nuclear Fuel Design Technology Development for the Future Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Yang Hyun; Lee, Byung Ho; Cheon, Jin Sik; Oh, Je Yong; Yim, Jeong Sik; Sohn, Dong Seong; Lee, Byung Uk; Ko, Han Suk; So, Dong Sup; Koo, Dae Seo


    The test MOX fuels have been irradiated in the Halden reactor, and their burnup attained 40 GWd/t as of October 2005. The fuel temperature and internal pressure were measured by the sensors installed in the fuels and test rig. The COSMOS code, which was developed by KAERI, well predicted in-reactor behavior of MOX fuel. The COSMOS code was verified by OECD-NEA benchmarks, and the result confirmed the superiority of COSMOS code. MOX in-pile database (IFA-629.3, IFA-610.2 and 4) in Halden was also used for the verification of code. The COSMOS code was improved by introducing Graphic User Interface (GUI) and batch mode. The PCMI analysis module was developed and introduced by the new fission gas behavior model. The irradiation test performed under the arbitrary rod internal pressure could also be analyzed with the COSMOS code. Several presentations were made for the preparation to transfer MOX fuel performance analysis code to the industry, and the transfer of COSMOS code to the industry is being discussed. The user manual and COSMOS program (executive file) were provided for the industry to test the performance of COSMOS code. To envisage the direction of research, the MOX fuel research trend of foreign countries, specially focused on USA's GENP policy, was analyzed.

  11. Spent fuel shipping cask accident evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Fields, S.R.


    Mathematical models have been developed to simulate the dynamic behavior, following a hypothetical accident and fire, of typical casks designed for the rail shipment of spent fuel from nuclear reactors, and to determine the extent of radioactive releases under postulated conditions. The casks modeled were the IF-300, designed by the General Electric Company for the shipment of spent LWR fuel, and a cask designed by the Aerojet Manufacturing Company for the shipment of spent LMFBR fuel.

  12. Comportement des pots catalytiques en présence de carburants oxygénés Behavior of Catalytic Mufflers in the Presence of Oxygenated Fuels

    Directory of Open Access Journals (Sweden)

    Degobert P.


    Full Text Available A partir d'un examen critique de la bibliographie disponible, et après un rappel des répercussions sur les émissions de la présence d'alcools dans les carburants, sont successivement examinées les performances d'épurateurs catalytiques multifonctionnels ou d'oxydation appliqués à des véhicules alimentés avec des carburants dont les teneurs en produits oxygénés varient entre 10 et 100 %. Les performances des catalyseurs s'écartent peu de celles constatées dans le cas de l'essence. Elles restent très bonnes vis-à-vis des polluants non réglementés. Par ailleurs, le pot catalytique n'engendre pas, dans ses conditions normales de fonctionnement, de polluants supplémentaires caractéristiques des combustibles oxygènes utilisés. Based on a critical examination of the literature available and after a review of the effects of the presence of alcools in fuels on emissions, this article successively examines the performances of multifunctional or oxidation catalytic scrubbers applied to vehicles fed with fuels containing between 10 and 100% oxygenated products. The performances of catalysts are not very different from those found with gasoline. They remain very good with regard to pollutants not covered by regulations. Furthermore, under normal operating conditions, a catalytic muffler does not produce any supplementary pollutants characteristic of the oxygenated fuels used.

  13. Transport fuel

    DEFF Research Database (Denmark)

    Ronsse, Frederik; Jørgensen, Henning; Schüßler, Ingmar


    Worldwide, the use of transport fuel derived from biomass increased four-fold between 2003 and 2012. Mainly based on food resources, these conventional biofuels did not achieve the expected emission savings and contributed to higher prices for food commod - ities, especially maize and oilseeds...

  14. Fuel Cells (United States)

    Hawkins, M. D.


    Discusses the theories, construction, operation, types, and advantages of fuel cells developed by the American space programs. Indicates that the cell is an ideal small-scale power source characterized by its compactness, high efficiency, reliability, and freedom from polluting fumes. (CC)

  15. Spent Nuclear Fuel Project Technical Databook

    Energy Technology Data Exchange (ETDEWEB)

    Reilly, M.A.


    The Spent Nuclear Fuel (SNF) Project Technical Databook is developed for use as a common authoritative source of fuel behavior and material parameters in support of the Hanford SNF Project. The Technical Databook will be revised as necessary to add parameters as their Databook submittals become available.

  16. Study of diffusion bond development in 6061 aluminum and its relationship to future high density fuels fabrication.

    Energy Technology Data Exchange (ETDEWEB)

    Prokofiev, I.; Wiencek, T.; McGann, D.


    Powder metallurgy dispersions of uranium alloys and silicides in an aluminum matrix have been developed by the RERTR program as a new generation of proliferation-resistant fuels. Testing is done with miniplate-type fuel plates to simulate standard fuel with cladding and matrix in plate-type configurations. In order to seal the dispersion fuel plates, a diffusion bond must exist between the aluminum coverplates surrounding the fuel meat. Four different variations in the standard method for roll-bonding 6061 aluminum were studied. They included mechanical cleaning, addition of a getter material, modifications to the standard chemical etching, and welding methods. Aluminum test pieces were subjected to a bend test after each rolling pass. Results, based on 400 samples, indicate that at least a 70% reduction in thickness is required to produce a diffusion bond using the standard rollbonding method versus a 60% reduction using the Type II method in which the assembly was welded 100% and contained open 9mm holes at frame corners.

  17. Metallic fuel design development

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Woan; Kang, H. Y.; Lee, B. O. and others


    This report describes the R and D results of the ''Metallic Fuel Design Development'' project that performed as a part of 'Nuclear Research and Development Program' during the '97 - '98 project years. The objectives of this project are to perform the analysis of thermo-mechanical and irradiation behaviors, and preliminary conceptual design for the fuel system of the KALIMER liquid metal reactor. The following are the major results that obtained through the project. The preliminary design requirements and design criteria which are necessary in conceptual design stage, are set up. In the field of fuel pin design, the pin behavior analysis, failure probability prediction, and sensitivity analysis are performed under the operation conditions of steady-state and transient accidents. In the area of assembly duct analysis; 1) KAFACON-2D program is developed to calculate an array configuration of inner shape of assembly duct, 2) Stress-strain analysis are performed for the components of assembly such as, handling socket, mounting rail and wire wrap, 3) The BDI program is developed to analyze mechanical interaction between pin bundle and duct, 4) a vibration analysis is performed to understand flow-induced vibration of assembly duct, 5) The NUBOW-2D, which is bowing and deformation analysis code for assembly duct, is modified to be operated in KALIMER circumstance, and integrity evaluation of KALIMER core assembly is carried out using the modified NUBOW-2D and the CRAMP code in U.K., and 6) The KALIMER assembly duct is manufactured to be used in flow test. In the area of non-fuel assembly, such as control, reflector, shielding, GEM and USS, the states-of-the-arts and the major considerations in designing are evaluated, and the design concepts are derived. The preliminary design description and their design drawing of KALIMER fuel system are prepared based upon the above mentioned evaluation and analysis. The achievement of conceptual

  18. Economic analysis of fuel treatments (United States)

    D. Evan Mercer; Jeffrey P. Prestemon


    The economics of wildfire is complicated because wildfire behavior depends on the spatial and temporal scale at which management decisions made, and because of uncertainties surrounding the results of management actions. Like the wildfire processes they seek to manage, interventions through fire prevention programs, suppression, and fuels management are scale dependent...

  19. Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi2/Si

    Directory of Open Access Journals (Sweden)

    Andrey V. Nomoev


    Full Text Available Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi2/Si were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM, X-ray diffraction (XRD, selective area electron diffraction (SAED, and energy dispersive X-ray fluorescence (EDX analysis. The system is compared to previously synthesized core-shell type particles in order to show possible differences responsible for the Janus-like structure forming instead of a core-shell architecture. It is proposed that the production of Janus-like as opposed to core-shell or monophase particles occurs due to the ability of Ta and Si to form compounds and the relative content of Ta and Si atoms in the produced vapour. Based on the results, a potential mechanism of formation for the TaSi2/Si nanoparticles is discussed.

  20. Low Contact Resistivity with Low Silicide/p+-Silicon Schottky Barrier for High-Performance p-Channel Metal-Oxide-Silicon Field Effect Transistors (United States)

    Tanaka, Hiroaki; Isogai, Tatsunori; Goto, Tetsuya; Teramoto, Akinobu; Sugawa, Shigetoshi; Ohmi, Tadahiro


    A current drivability improvement of p-channel metal-oxide-silicon field effect transistors (MOSFETs) is necessary for the performance enhancement of complementary metal-oxide-semiconductor (CMOS) circuits. In this paper, we present the key technology for fabricating indispensable CMOS circuits with a small Schottky barrier height and a low contact resistance for p-type silicon using Pd2Si. We fabricated a Pd2Si gate Schottky barrier diode and a Kelvin pattern on silicon. The measured Schottky barrier height is 0.29 eV for p-type silicon. We also realized a very low contact resistivity of 3.7 ×10-9 Ω cm2 for the p+ region of silicon. The p-channel MOSFET with Pd2Si source/drain contacts realized a good characteristic, that is, a small off current. The technology developed in this work involves silicide formation for source/drain contacts of p-channel MOSFETs, which is expected to realize the performance enhancement of MOSFETs.

  1. Fabrication and microstructural analysis of UN-U3Si2 composites for accident tolerant fuel applications (United States)

    Johnson, Kyle D.; Raftery, Alicia M.; Lopes, Denise Adorno; Wallenius, Janne


    In this study, U3Si2 was synthesized via the use of arc-melting and mixed with UN powders, which together were sintered using the SPS method. The study revealed a number of interesting conclusions regarding the stability of the system - namely the formation of a probable but as yet unidentified ternary phase coupled with the reduction of the stoichiometry in the nitride phase - as well as some insights into the mechanics of the sintering process itself. By milling the silicide powders and reducing its particle size ratio compared to UN, it was possible to form a high density UN-U3Si2 composite, with desirable microstructural characteristics for accident tolerant fuel applications.

  2. The effect of post-treatment of a high-velocity oxy-fuel Ni-Cr-Mo-Si-B coating Part I: Microstructure/corrosion behavior relationships (United States)

    Shrestha, S.; Hodgkiess, T.; Neville, A.


    The microstructure and aqueous corrosion characteristics of a Ni-Cr-Mo-Si-B high-velocity oxy-fuel (HVOF) coating have been assessed. It has been shown that postprocessing by vacuum fusion has a significant effect on the coating microstructure by increasing the type and concentration of hard phase particles. The principal hard phases in the as-sprayed condition and vacuum-sealed condition are chromium carbides, whereas molybdenum-containing boride phases are also present after vacuum fusion. Vacuumfusion post-treatment eliminates splat boundaries, which can act as sites, where preferential corrosion can occur and, hence, the dominant corrosion mechanisms change. In as-sprayed and vacuum-sealed coatings, localized attack at splat particle boundaries and crevice corrosion dominate, whereas in vacuum-fused coating, the principal mechanism of corrosion is “micropitting” as a result of the hard phase loss.

  3. Electrochemical Behavior and Hydrophobic Properties of CrN and CrNiN Coatings in Simulated Proton Exchange Membrane Fuel Cell Environment

    Directory of Open Access Journals (Sweden)

    JIN Jie


    Full Text Available The CrN and CrNiN coatings were prepared on the surface of 304 stainless steel by closed field unbalanced magnetron sputtering.X ray diffraction and field emission scanning electron microscopy were used to characterize the structure and morphology of the coatings.The electrochemical corrosion properties under the simulated proton exchange membrane fuel cell(PEMFC environment, interfacial contact resistance and hydrophobic properties of the two kinds of different coatings were investigated by electrochemical methods,contact resistance test and hydrophobic test,respectively.The results indicate that CrN coating mainly consists of CrN and Cr2N phase,CrN and Cr2N phases in the CrNiN coating are less compared to CrN film, and Ni exist as element in CrNiN coating; dynamic polarization tests show the coating is of better corrosion resistance,whereas the corrosion resistance of CrNiN coating is worse than that of CrN coating,constant potential polarization test shows the corrosion current density of CrN and CrNiN coatings are equivalent; CrN and CrNiN coatings significantly reduce the interfacial contact resistance of the 304 stainless steel,among which CrN coating has the smallest contact resistance; and CrNiN coating which has better hydrophobicity than that of CrN coating is more beneficial for the water management in proton exchange membrane fuel cell.

  4. Fire Behavior (FB) (United States)

    Robert E. Keane


    The Fire Behavior (FB) method is used to describe the behavior of the fire and the ambient weather and fuel conditions that influence the fire behavior. Fire behavior methods are not plot based and are collected by fire event and time-date. In general, the fire behavior data are used to interpret the fire effects documented in the plot-level sampling. Unlike the other...

  5. Fuel Characteristic Classification System version 3.0: technical documentation (United States)

    Susan J. Prichard; David V. Sandberg; Roger D. Ottmar; Ellen Eberhardt; Anne Andreu; Paige Eagle; Kjell. Swedin


    The Fuel Characteristic Classification System (FCCS) is a software module that records wildland fuel characteristics and calculates potential fire behavior and hazard potentials based on input environmental variables. The FCCS 3.0 is housed within the Integrated Fuels Treatment Decision Support System (Joint Fire Science Program 2012). It can also be run from command...

  6. Effect of High Si Content on U3Si2 Fuel Microstructure (United States)

    Rosales, Jhonathan; van Rooyen, Isabella J.; Meher, Subhashish; Hoggan, Rita; Parga, Clemente; Harp, Jason


    The development of U3Si2 as an accident-tolerant nuclear fuel has gained research interest because of its promising high uranium density and improved thermal properties. In the present study, three samples of U3Si2 fuel with varying silicon content have been fabricated by a conventional powder metallurgical route. Microstructural characterization via scanning and transmission electron microscopy reveals the presence of other stoichiometry of uranium silicide such as USi and UO2 in both samples. The detailed phase analysis by x-ray diffraction shows the presence of secondary phases, such as USi, U3Si, and UO2. The samples with higher concentrations of silicon content of 7.5 wt.% display additional elemental Si. These samples also possess an increased amount of the USi phase as compared to that in the conventional sample with 7.3 wt.% silicon. The optimization of U3Si2 fuel performance through the understanding of the role of Si content on its microstructure has been discussed.

  7. Non destructive examination of UN / U-Si fuel pellets using neutrons (preliminary assessment)

    Energy Technology Data Exchange (ETDEWEB)

    Bourke, Mark Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vogel, Sven C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Voit, Stewart Lancaster [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Losko, Adrian S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tremsin, Anton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Tomographic imaging and diffraction measurements were performed on nine pellets; four UN/ U Si composite formulations (two enrichment levels), three pure U3Si5 reference formulations (two enrichment levels) and two reject pellets with visible flaws (to qualify the technique). The U-235 enrichments ranged from 0.2 to 8.8 wt.%. The nitride/silicide composites are candidate compositions for use as Accident Tolerant Fuel (ATF). The monophase U3Si5 material was included as a reference. Pellets from the same fabrication batches will be inserted in the Advanced Test Reactor at Idaho during 2016. The goal of the Advanced Non-destructive Fuel Examination work package is the development and application of non-destructive neutron imaging and scattering techniques to ceramic and metallic nuclear fuels. Data reported in this report were collected in the LANSCE run cycle that started in September 2015 and ended in March 2016. Data analysis is ongoing; thus, this report provides a preliminary review of the measurements and provides an overview of the characterized samples.

  8. Fuel performance evaluation for the CAFE experimental device

    Energy Technology Data Exchange (ETDEWEB)

    Giovedi, Claudia; Hirota, Leandro T., E-mail: [Centro Tecnologico da Marinha em Sao Paulo (CTMSP/CEA), Ipero, SP (Brazil). Dept. de Tecnologia de Reatores Nucleares; Gomes, Daniel S.; Abe, Alfredo Y.; Silva, Antonio Teixeira e, E-mail: teixeira@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)


    Fuel rod cladding material is the second barrier to prevent the release of radioactive inventories in a PWR reactor. In this sense, an important safety aspect is to assess the fuel behavior under operational conditions. This can be made by means of fuel performance codes and confirmed by experimental measurements. In order to evaluate the fuel behavior of fuel rods in steady-state conditions, it was designed an experimental irradiation device, the Nuclear Fuel Irradiation Circuit (CAFE-Mod1). This device will allow controlling the surface rod temperature, to measure the power associated to the rod and the evolution of fission gas release for a typical PWR fuel pin. However, to support the experimental irradiation program, it is extremely important to simulate the experimental conditions using a fuel performance code. The aim of this paper is to evaluate some parameters and aspects related to the fuel rod behavior during the irradiation program. This evaluation was carried out by means of an adapted fuel performance code. Obtained results have shown that besides of the variation observed for parameters, such as, fuel temperature and fission gas release as a function of fuel enrichment level, the fuel rod integrity was preserved in all studied conditions. (author)

  9. Fuel-rich catalytic combustion of a high density fuel (United States)

    Brabbs, Theodore A.; Merritt, Sylvia A.


    Fuel-rich catalytic combustion (ER is greater than 4) of the high density fuel exo-tetrahydrocyclopentadiene (JP-10) was studied over the equivalence ratio range 5.0 to 7.6, which yielded combustion temperatures of 1220 to 1120 K. The process produced soot-free gaseous products similar to those obtained with iso-octane and jet-A in previous studies. The measured combustion temperature agreed well with that calculated assuming soot was not a combustion product. The process raised the effective hydrogen/carbon (H/C) ratio from 1.6 to over 2.0, thus significantly improving the combustion properties of the fuel. At an equivalence ratio near 5.0, about 80 percent of the initial fuel carbon was in light gaseous products and about 20 percent in larger condensable molecules. Fuel-rich catalytic combustion has now been studied for three fuels with H/C ratios of 2.25 (iso-octane), 1.92 (jet-A), and 1.6 (JP-10). A comparison of the product distribution of these fuels shows that, in general, the measured concentrations of the combustion products were monotonic functions of the H/C ratio with the exception of hydrogen and ethylene. In these cases, data for JP-10 fell between iso-octane and jet-A rather than beyond jet-A. It is suggested that the ring cross-linking structure of JP-10 may be responsible for this behavior. All the fuels studied showed that the largest amounts of small hydrocarbon molecules and the smallest amounts of large condensable molecules occurred at the lower equivalence ratios. This corresponds to the highest combustion temperatures used in these studies. Although higher temperatures may improve this mix, the temperature is limited. First, the life of the present catalyst would be greatly shortened when operated at temperatures of 1300 K or greater. Second, fuel-rich catalytic combustion does not produce soot because the combustion temperatures used in the experiments were well below the threshold temperature (1350 K) for the formation of soot. Increasing

  10. Assessing three fuel classification systems and their maps using Forest Inventory and Analysis (FIA) surface fuel measurements (United States)

    Robert E. Keane; Jason M. Herynk; Chris Toney; Shawn P. Urbanski; Duncan C. Lutes; Roger D. Ottmar


    Fuel classifications are integral tools in fire management and planning because they are used as inputs to fire behavior and effects simulation models. Fuel Loading Models (FLMs) and Fuel Characteristic Classification System (FCCSs) fuelbeds are the most popular classifications used throughout wildland fire science and management, but they have yet to be thoroughly...

  11. Fundamental aspects of nuclear reactor fuel elements

    Energy Technology Data Exchange (ETDEWEB)

    Olander, D.R.


    The book presented is designed to function both as a text for first-year graduate courses in nuclear materials and as a reference for workers involved in the materials design and performance aspects of nuclear power plants. The contents are arranged under the following chapter headings: statistical thermodynamics, thermal properties of solids, crystal structures, cohesive energy of solids, chemical equilibrium, point defects in solids, diffusion in solids, dislocations and grain boundaries, equation of state of UO/sub 2/, fuel element thermal performance, fuel chemistry, behavior of solid fission products in oxide fuel elements, swelling due to fission gases, pore migration and fuel restructuring kinetics, fission gas release, mechanical properties of UO/sub 2/, radiation damage, radiation effects in metals, interaction of sodium and stainless steel, modeling of the structural behavior of fuel elements and assemblies. (DG)

  12. RERTR Fuel Developmemt and Qualification Plan

    Energy Technology Data Exchange (ETDEWEB)

    Dan Wachs


    detailing very-high density fuel behavior will be submitted to the U.S. Nuclear Regulatory Commission (NRC). Assuming acceptable fuel behavior, it is anticipated that NRC will issue a Safety Evaluation Report granting generic approval of the developed fuels based on the qualification report. It is anticipated that Phase I of fuel qualification will be completed prior to the end of FY10. Phase II of the fuel qualification requires development of fuels with density greater than 8.5 g-U/cm3. This fuel is required to convert the remaining few reactors that have been identified for conversion. The second phase of the fuel qualification effort includes both dispersion fuels with fuel particle volume loading on the order of 65 percent, and monolithic fuels. Phase II presents a larger set of technical unknowns and schedule uncertainties than phase I. The final step in the fuel qualification process involves insertion of lead test elements into the converting reactors. Each reactor that plans to convert using the developed high-density fuels will develop a reactor specific conversion plan based upon the reactor safety basis and operating requirements. For some reactors (FRM-II, High-Flux Isotope Reactor [HFIR], and RHF) conversion will be a one-step process. In addition to the U.S. fuel development effort, a Russian fuel development strategy has been developed. Contracts with Russian Federation institutes in support of fuel development for Russian are in place.

  13. Experimental Results for SimFuels

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Edgar C.; Casella, Andrew M.; Skomurski, Frances N.; MacFarlan, Paul J.; Soderquist, Chuck Z.; Wittman, Richard S.; Mcnamara, Bruce K.


    Assessing the performance of Spent (or Used) Nuclear Fuel (UNF) in geological repository requires quantification of time-dependent phenomena that may influence its behavior on a time-scale up to millions of years. A high-level waste repository environment will be a dynamic redox system because of the time-dependent generation of radiolytic oxidants and reductants and the corrosion of Fe-bearing canister materials. One major difference between used fuel and natural analogues, including unirradiated UO2, is the intense radiolytic field. The radiation emitted by used fuel can produce radiolysis products in the presence of water vapor or a thin-film of water that may increase the waste form degradation rate and change radionuclide behavior. To study UNF, we have been working on producing synthetic UO2 ceramics, or SimFuels that can be used in testing and which will contain specific radionuclides or non-radioactive analogs so that we can test the impact of radiolysis on fuel corrosion without using actual spent fuel. Although, testing actual UNF would be ideal for understanding the long term behavior of UNF, it requires the use of hot cells and is extremely expensive. In this report, we discuss, factors influencing the preparation of SimFuels and the requirements for dopants to mimic the behavior of UNF. We have developed a reliable procedure for producing large grain UO2 at moderate temperatures. This process will be applied to a series of different formulations.

  14. Probabilistic methods for the simulation of fuel particles behavior under irradiation; Apport des methodes probabilistes dans la simulation du comportement sous irradiation du combustible a particules

    Energy Technology Data Exchange (ETDEWEB)

    Cannamela, C


    This work is devoted to the evaluation of mathematical expectations in the context of structural reliability. We seek a failure probability estimate (that we assume low), taking into account the uncertainty of influential parameters of the System. Our goal is to reach a good compromise between the accuracy of the estimate and the associated computational cost. This approach is used to estimate the failure probability of fuel particles from a HTR-type nuclear reactor. This estimate is obtain by means of costly numerical simulations. We consider different probabilistic methods to tackle the problem. First, we consider a variance reducing Monte Carlo method: importance sampling. For the parametric case, we propose adaptive algorithms in order to build a series of probability densities that will eventually converge to optimal importance density. We then present several estimates of the mathematical expectation based on this series of densities. Next, we consider a multi-level method using Monte Carlo Markov Chain algorithm. Finally, we turn our attention to the related problem of quantile estimation (non extreme) of physical output from a large-scale numerical code. We propose a controlled stratification method. The random input parameters are sampled in specific regions obtained from surrogate of the response. The estimation of the quantile is then computed from this sample. (author)

  15. Comparison of in vitro behavior of as-sprayed, alkaline-treated and collagen-treated bioceramic coatings obtained by high velocity oxy-fuel spray

    Energy Technology Data Exchange (ETDEWEB)

    Melero, H., E-mail: [Thermal Spray Centre, Universitat de Barcelona, Martí i Franqués, 1, 08028 Barcelona (Spain); Garcia-Giralt, N. [URFOA, IMIM (Institut Hospital del Mar d’Investigacions Mèdiques), RETICEF, Doctor Aiguader, 80, 08003 Barcelona (Spain); Fernández, J. [Thermal Spray Centre, Universitat de Barcelona, Martí i Franqués, 1, 08028 Barcelona (Spain); Díez-Pérez, A. [URFOA, IMIM (Institut Hospital del Mar d’Investigacions Mèdiques), RETICEF, Doctor Aiguader, 80, 08003 Barcelona (Spain); Servei de Medicina Interna, Hospital del Mar, Barcelona (Spain); Guilemany, J.M. [Thermal Spray Centre, Universitat de Barcelona, Martí i Franqués, 1, 08028 Barcelona (Spain)


    Hydroxyapatite (HAp)–TiO{sub 2} samples obtained using high velocity oxy-fuel spray (HVOF), that had previously shown excellent mechanical behaviour, were innovatively surface treated in order to improve their biological performance. The chosen treatments were an alkaline treatment to increase –OH radicals density on the surface (especially on TiO{sub 2} zones), and a collagen treatment to bond collagen fibrils to the –OH radicals present in hydroxyapatite. These coatings were analysed using scanning electron microscopy, energy-dispersive X-ray spectroscopy and infrared spectroscopy, and tested for human osteoblast biocompatibility and functionality. In the case of the alkaline treatment, although the –OH radicals density did not increase compared to the as-sprayed coatings, a nanostructured layer of sodium hydroxycarbonate precipitated on the surface, thus improving biological behaviour due to the nanoroughness effect. For the collagen-treated samples, collagen fibrils appeared well-adhered to the surface, and in vitro cell culture tests showed that these surfaces were much more conducive to cell adhesion and differentiation than the as-sprayed and alkaline-treated samples. These results pointed to collagen treatment as a very promising method to improve bioactivity of HAp–TiO{sub 2} thermal-sprayed coatings.

  16. Nuclear Fuels: Present and Future

    Directory of Open Access Journals (Sweden)

    Donald R. Olander


    Full Text Available The important new developments in nuclear fuels and their problems are reviewed and compared with the status of present light-water reactor fuels. The limitations of these fuels and the reactors they power are reviewed with respect to important recent concerns, namely provision of outlet coolant temperatures high enough for use in H2 production, destruction of plutonium to eliminate proliferation concerns, and burning of the minor actinides to reduce the waste repository heat load and long-term radiation hazard. In addition to current oxide-based fuel-rod designs, the hydride fuel with liquid metal thermal bonding of the fuel-cladding gap is covered. Finally, two of the most promising Generation IV reactor concepts, the Very High Temperature Reactor and the Sodium Fast Reactor, and the accompanying reprocessing technologies, aqueous-based UREX and pyrometallurgical, are summarized. In all of the topics covered, the thermodynamics involved in the material's behavior under irradiation and in the reprocessing schemes are emphasized.

  17. Spent fuel and fuel pool component integrity. Annual report, FY 1980

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, A.B. Jr.; Bailey, W.J.; Bradley, E.R.; Bruemmer, S.M.; Langstaff, D.C.


    During program FY 1980 staff members of the Spent Fuel and Fuel Pool Component Integrity Program at Pacific Northwest Laboratory (PNL) completed the following major tasks: represented DOE on the international Behavior of Fuel Assemblies in Storage (BEFAST) Committee; the program manager, A.B. Johnson, Jr., participated in an International Survey of Water Reactor Spent Fuel Storage Experience, which was conducted jointly by the International Atomic Energy Agency (Vienna) and the Nuclear Energy Agency (Paris); provided written testimony and cross statement for the Proposed Rulemaking on Storage and Disposal of Nuclear Waste; acquired and began examination of the world's oldest pool-stored Zircaloy-clad fuel from the Shippingport reactor, stored approx. 21 years in deionized water; acquired and began examination of stainless-clad spent fuel from the Connecticut Yankee Reactor (PWR); negotiated for specimens from components stored in spent fuel pools at fuel storage facilities from the Savannah River Plant, Aiken, South Carolina, Zion (PWR) spent fuel pool, Zion, Illinois, and La Crosse (BWR) spent fuel pool, La Crosse, Wisconsin; planned for examinations in FY 81 of specimens from the three spent fuel pools; investigated a low-temperature stress corrosion cracking mechanism that developed in piping at a few PWR spent fuel pools. This report summarizes the results of these activities and investigations. Details are provided in the presentationsand publications generated under this program and summarized in Appendix A.

  18. Fuel utilization and fuel sensitivity of solid oxide fuel cells (United States)

    Huang, Kevin


    Fuel utilization and fuel sensitivity are two important process variables widely used in operation of SOFC cells, stacks, and generators. To illustrate the technical values, the definitions of these two variables as well as practical examples are particularly given in this paper. It is explicitly shown that the oxygen-leakage has a substantial effect on the actual fuel utilization, fuel sensitivity and V-I characteristics. An underestimation of the leakage flux could potentially results in overly consuming fuel and oxidizing Ni-based anode. A fuel sensitivity model is also proposed to help extract the leakage flux information from a fuel sensitivity curve. Finally, the "bending-over" phenomenon observed in the low-current range of a V-I curve measured at constant fuel-utilization is quantitatively coupled with leakage flux.

  19. Mechanical mastication as a fuels treatment in southeastern forests (United States)

    Jesse K. Kreye; J. Morgan Varner; Leda N. Kobziar


    Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity. Despite its widespread adoption, it remains unclear how mastication impacts fuels, fire behavior, or plant communities  across Southeastern forest ecosystems. We evaluated these...

  20. Power generation from solid fuels

    CERN Document Server

    Spliethoff, Hartmut


    Power Generation from Solid Fuels introduces the different technologies to produce heat and power from solid fossil (hard coal, brown coal) and renewable (biomass, waste) fuels, such as combustion and gasification, steam power plants and combined cycles etc. The book discusses technologies with regard to their efficiency, emissions, operational behavior, residues and costs. Besides proven state of the art processes, the focus is on the potential of new technologies currently under development or demonstration. The main motivation of the book is to explain the technical possibilities for reduci

  1. Ecological forestry in the Southeast: Understanding the ecology of fuels (United States)

    R.J. Mitchell; J.K. Hiers; J. O’Brien; G. Starr


    Fire is a dominant disturbance within many forested ecosystems worldwide. Understanding the complex feedbacks among vegetation as a fuel for fire, the effects of fuels on fire behavior, and the impact of fire behavior on future vegetation are critical for sustaining biodiversity in fire-dependent forests. Nonetheless, understanding in fire ecology has been limited in...

  2. Chapter 2: Fire and Fuels Extension: Model description (United States)

    Sarah J. Beukema; Elizabeth D. Reinhardt; Julee A. Greenough; Donald C. E. Robinson; Werner A. Kurz


    The Fire and Fuels Extension to the Forest Vegetation Simulator is a model that simulates fuel dynamics and potential fire behavior over time, in the context of stand development and management. Existing models are used to represent forest stand development (the Forest Vegetation Simulator, Wykoff and others 1982), fire behavior (Rothermel 1972, Van Wagner 1977, and...

  3. Fuel treatment longevity in a Sierra Nevada mixed conifer forest (United States)

    Scott. L. Stephens; Brandon M. Collins; Gary. Roller


    Understanding the longevity of fuel treatments in terms of their ability to maintain fire behavior and effects within a desired range is an important question. The objective of this study was to determine how fuels, forest structure, and predicted fire behavior changed 7-years after initial treatments. Three different treatments: mechanical only, mechanical plus fire,...

  4. Oxidation Behavior and Electrical Properties of NiO- and Cr2O3- Forming Alloys for Solid Oxide Fuel Cell Interconnects.

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Michael P [ORNL; Pint, Bruce A [ORNL; Lu, Z G [Tennessee Technological University; Zhu, Jiahong [ORNL; Milliken, C [TMI Inc; kreidler, E [TMI Inc; Miller, Leslie S [ORNL; Armstrong, Timothy R. [ORNL; Walker, Larry R [ORNL


    The goal of this paper was to determine if NiO-forming alloys are a viable alternative to Cr{sub 2}O{sub 3}-forming alloys for solid-oxide fuel-cell (SOFC) metallic interconnects. The oxide-scale growth kinetics and electrical properties of a series of Li- and Y{sub 2}O{sub 3}-alloyed, NiO-forming Ni-base alloys and La-, Mn-, and Ti-alloyed Fe-18Cr-9W and Fe-25Cr base ferritic Cr{sub 2}O{sub 3}-forming alloys were evaluated. The addition of Y{sub 2}O{sub 3} and Li reduced the NiO scale growth rate and increased its electrical conductivity. The area-specific-resistance (ASR) values were comparable to those of the best (lowest ASR) ferritic alloys examined. Oxidation of the ferritic alloys at 800 C in air and air+10% H{sub 2}O (water vapor) indicated that Mn additions resulted in faster oxidation kinetics/thicker oxide scales, but also lower oxide scale ASRs. Relative in-cell performance in model SOFC stacks operated at 850 C indicated a 60-80% reduction in ASR by Ni+Y{sub 2}O{sub 3}, Ni+Y{sub 2}O{sub 3}, Li, and Fe-25Cr+La,Mn,Ti interconnects over those made from a baseline, commercial Cr{sub 2}O{sub 3}-forming alloy. Collectively, these results indicate that NiO-forming alloys show potential for use as metallic interconnects.

  5. Fuel processors for fuel cell APU applications (United States)

    Aicher, T.; Lenz, B.; Gschnell, F.; Groos, U.; Federici, F.; Caprile, L.; Parodi, L.

    The conversion of liquid hydrocarbons to a hydrogen rich product gas is a central process step in fuel processors for auxiliary power units (APUs) for vehicles of all kinds. The selection of the reforming process depends on the fuel and the type of the fuel cell. For vehicle power trains, liquid hydrocarbons like gasoline, kerosene, and diesel are utilized and, therefore, they will also be the fuel for the respective APU systems. The fuel cells commonly envisioned for mobile APU applications are molten carbonate fuel cells (MCFC), solid oxide fuel cells (SOFC), and proton exchange membrane fuel cells (PEMFC). Since high-temperature fuel cells, e.g. MCFCs or SOFCs, can be supplied with a feed gas that contains carbon monoxide (CO) their fuel processor does not require reactors for CO reduction and removal. For PEMFCs on the other hand, CO concentrations in the feed gas must not exceed 50 ppm, better 20 ppm, which requires additional reactors downstream of the reforming reactor. This paper gives an overview of the current state of the fuel processor development for APU applications and APU system developments. Furthermore, it will present the latest developments at Fraunhofer ISE regarding fuel processors for high-temperature fuel cell APU systems on board of ships and aircrafts.

  6. Renewable Fuel Standard Program (United States)

    Information about regulations, developed by EPA, in collaboration with refiners, renewable fuel producers, and many other stakeholders, that ensure that transportation fuel sold in the United States contains a minimum volume of renewable fuel.

  7. Logistic Fuel Processor Development

    National Research Council Canada - National Science Library

    Salavani, Reza


    The Air Base Technologies Division of the Air Force Research Laboratory has developed a logistic fuel processor that removes the sulfur content of the fuel and in the process converts logistic fuel...

  8. Structural, magnetic and microwave absorption behavior of Co-Zr substituted strontium hexaferrites prepared using tartaric acid fuel for electromagnetic interference suppression

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Prabhjyot, E-mail: [Department of Chemistry, Centre for Advanced Studies-I, Guru Nanak Dev University, Amritsar 143005 (India); Chawla, S.K., E-mail: [Department of Chemistry, Centre for Advanced Studies-I, Guru Nanak Dev University, Amritsar 143005 (India); Narang, Sukhleen Bindra, E-mail: [Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005 (India); Pubby, Kunal, E-mail: [Department of Electronics Technology, Guru Nanak Dev University, Amritsar 143005 (India)


    Strontium hexaferrites, doped with varying Co-Zr content (x) have been synthesized by sol-gel auto-combustion route using tartaric acid as fuel at 800 °C. X-ray diffraction and Fourier transform Infra-red have been carried out to confirm the phase formation, particle size (average 21.9–36.8 nm) and the bond formation respectively. Magnetic properties are scrutinized using vibrating sample magnetometer. Techniques like scanning electron microscopy, transmission electron microscopy and energy dispersive scattering have been employed to explore the surface morphology, particle size and composition of the nano-powders. Electromagnetic characterization of the prepared ferrites has been done using Vector Network Anlyzer in 12.4–18 GHz frequency range. The effect of calcination temperature (500–1000 °C) on the structure, morphology and magnetic properties has also been studied for x=0.2 and 800 °C has been found to be the most suitable temperature with the best magnetic properties. Increase in doping has resulted in resonance peaks in dielectric and magnetic loss spectra, leading to microwave absorption peaks. Ferrites with x=0.2, 0.8 and 1.0 have appropriate reflection loss less than −10 dB and bandwidth in Ku-band, hence can be used as effective absorbers in suppression of electromagnetic interference (EMI). The governance of impedance matching in deciding the absorption properties has been proved by using input impedance calculations. - Highlights: • Co-Zr doped strontium hexaferrite nanopowders have been prepared by sol-gel route. • 800 °C was most suitable temperaturewith best structural and magnetic properties. • Samples have M-type hexagonal structure with an average particle size of 36.47 nm. • Samples x=0.2, 0.8 and 1.0 are suitable for suppression of EM waves in Ku-band. • The origin of absorption peaks: impedance matching and losses has been explained.

  9. The photoload sampling technique: estimating surface fuel loadings from downward-looking photographs of synthetic fuelbeds (United States)

    Robert E. Keane; Laura J. Dickinson


    Fire managers need better estimates of fuel loading so they can more accurately predict the potential fire behavior and effects of alternative fuel and ecosystem restoration treatments. This report presents a new fuel sampling method, called the photoload sampling technique, to quickly and accurately estimate loadings for six common surface fuel components (1 hr, 10 hr...

  10. Post-fire logging reduces surface woody fuels up to four decades following wildfire (United States)

    David W. Peterson; Erich Kyle Dodson; Richy J. Harrod


    Severe wildfires create pulses of dead trees that influence future fuel loads, fire behavior, and fire effects as they decay and deposit surface woody fuels. Harvesting fire-killed trees may reduce future surface woody fuels and related fire hazards, but the magnitude and timing of post-fire logging effects on woody fuels have not been fully assessed. To address this...

  11. Dynamic characteristics of an automotive fuel cell system for transitory load changes

    DEFF Research Database (Denmark)

    Rabbani, Raja Abid; Rokni, Masoud


    A dynamic model of Polymer Electrolyte Membrane Fuel Cell (PEMFC) system is developed to investigate the behavior and transient response of a fuel cell system for automotive applications. Fuel cell dynamics are subjected to reactant flows, heat management and water transportation inside the fuel...

  12. Modeling moisture content of fine dead wildland fuels: Input to the BEHAVE fire prediction system (United States)

    Richard C. Rothermel; Ralph A. Wilson; Glen A. Morris; Stephen S. Sackett


    Describes a model for predicting moisture content of fine fuels for use with the BEHAVE fire behavior and fuel modeling system. The model is intended to meet the need for more accurate predictions of fine fuel moisture, particularly in northern conifer stands and on days following rain. The model is based on the Canadian Fine Fuel Moisture Code (FFMC), modified to...

  13. Fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Hirofumi.


    This invention aims to maintain a long-term operation with stable cell output characteristics by uniformly supplying an electrolyte from the reserver to the matrix layer over the entire matrix layer, and further to prevent the excessive wetting of the catalyst layer by smoothly absorbing the volume change of the electrolyte, caused by the repeated stop/start-up of the fuel cell, within the reserver system. For this purpose, in this invention, an electrolyte transport layer, which connects with an electrolyte reservor formed at the electrode end, is partly formed between the electrode material and the catalyst layer; a catalyst layer, which faces the electrolyte transport layer, has through-holes, which connect to the matrix, dispersely distributed. The electrolyte-transport layer is a thin sheet of a hydrophilic fibers which are non-wovens of such fibers as carbon, silicon carbide, silicon nitride or inorganic oxides. 11 figs.

  14. Operando fuel cell spectroscopy (United States)

    Kendrick, Ian Michael

    The active state of a catalyst only exists during catalysis (1) provided the motivation for developing operando spectroscopic techniques. A polymer electrolyte membrane fuel cell (PEMFC) was designed to interface with commercially available instruments for acquisition of infrared spectra of the catalytic surface of the membrane electrode assembly (MEA) during normal operation. This technique has provided insight of the complex processes occurring at the electrode surface. Nafion, the solid electrolyte used in most modern-day polymer electrolyte membrane fuel cells (PEMFC), serves many purposes in fuel cell operation. However, there is little known of the interface between Nafion and the electrode surface. Previous studies of complex Stark tuning curves of carbon monoxide on the surface of a platinum electrode were attributed the co-adsorption of bisulfite ions originating from the 0.5M H2SO4 electrolyte used in the study(2). Similar tuning curves obtained on a fuel cell MEA despite the absence of supplemental electrolytes suggest the adsorption of Nafion onto platinum (3). The correlation of spectra obtained using attenuated total reflectance spectroscopy (ATR) and polarization modulated IR reflection-absorption spectroscopy (PM-IRRAS) to a theoretical spectrum generated using density functional theory (DFT) lead to development of a model of Nafion and platinum interaction which identified participation of the SO3- and CF3 groups in Nafion adsorption. The use of ethanol as a fuel stream in proton exchange membrane fuel cells provides a promising alternative to methanol. Relative to methanol, ethanol has a greater energy density, lower toxicity and can be made from the fermentation of biomass(4). Operando IR spectroscopy was used to study the oxidation pathway of ethanol and Stark tuning behavior of carbon monoxide on Pt, Ru, and PtRu electrodes. Potential dependent products such as acetaldehyde, acetic acid and carbon monoxide are identified as well as previously

  15. Fuel processor for fuel cell power system (United States)

    Vanderborgh, Nicholas E.; Springer, Thomas E.; Huff, James R.


    A catalytic organic fuel processing apparatus, which can be used in a fuel cell power system, contains within a housing a catalyst chamber, a variable speed fan, and a combustion chamber. Vaporized organic fuel is circulated by the fan past the combustion chamber with which it is in indirect heat exchange relationship. The heated vaporized organic fuel enters a catalyst bed where it is converted into a desired product such as hydrogen needed to power the fuel cell. During periods of high demand, air is injected upstream of the combustion chamber and organic fuel injection means to burn with some of the organic fuel on the outside of the combustion chamber, and thus be in direct heat exchange relation with the organic fuel going into the catalyst bed.

  16. Fuels Combustion Research: Supercritical Fuel Pyrolysis

    National Research Council Canada - National Science Library

    Glassman, Irvin


    .... The focus during the subject period was directed to understanding the pyrolysis and combustion of endothermic fuels under subcritical conditions and the pyrolysis of these fuels under supercritical conditions...

  17. Fuels Combustion Research: Supercritical Fuel Pyrolysis

    National Research Council Canada - National Science Library

    Glassman, Irvin


    .... The focus during the subject period was directed to understanding the pyrolysis and combustion of endothermic fuels under subcritical conditions and the pyrolysis of these fuels under supercritical conditions...

  18. A methodology for assessing the market benefits of alternative motor fuels: The Alternative Fuels Trade Model

    Energy Technology Data Exchange (ETDEWEB)

    Leiby, P.N.


    This report describes a modeling methodology for examining the prospective economic benefits of displacing motor gasoline use by alternative fuels. The approach is based on the Alternative Fuels Trade Model (AFTM). AFTM development was undertaken by the US Department of Energy (DOE) as part of a longer term study of alternative fuels issues. The AFTM is intended to assist with evaluating how alternative fuels may be promoted effectively, and what the consequences of substantial alternative fuels use might be. Such an evaluation of policies and consequences of an alternative fuels program is being undertaken by DOE as required by Section 502(b) of the Energy Policy Act of 1992. Interest in alternative fuels is based on the prospective economic, environmental and energy security benefits from the substitution of these fuels for conventional transportation fuels. The transportation sector is heavily dependent on oil. Increased oil use implies increased petroleum imports, with much of the increase coming from OPEC countries. Conversely, displacement of gasoline has the potential to reduce US petroleum imports, thereby reducing reliance on OPEC oil and possibly weakening OPEC`s ability to extract monopoly profits. The magnitude of US petroleum import reduction, the attendant fuel price changes, and the resulting US benefits, depend upon the nature of oil-gas substitution and the supply and demand behavior of other world regions. The methodology applies an integrated model of fuel market interactions to characterize these effects.

  19. Catalytic Fuel Conversion Facility (United States)

    Federal Laboratory Consortium — This facility enables unique catalysis research related to power and energy applications using military jet fuels and alternative fuels. It is equipped with research...

  20. GSPEL - Fuel Cell Laboratory (United States)

    Federal Laboratory Consortium — The Fuel Cell Lab (FCL)Established to investigate, integrate, testand verifyperformance and technology readiness offuel cell systems and fuel reformers for use with...

  1. Internal reforming fuel cell assembly with simplified fuel feed (United States)

    Farooque, Mohammad; Novacco, Lawrence J.; Allen, Jeffrey P.


    A fuel cell assembly in which fuel cells adapted to internally reform fuel and fuel reformers for reforming fuel are arranged in a fuel cell stack. The fuel inlet ports of the fuel cells and the fuel inlet ports and reformed fuel outlet ports of the fuel reformers are arranged on one face of the fuel cell stack. A manifold sealing encloses this face of the stack and a reformer fuel delivery system is arranged entirely within the region between the manifold and the one face of the stack. The fuel reformer has a foil wrapping and a cover member forming with the foil wrapping an enclosed structure.

  2. Oxidation behavior and area specific resistance of La, Cu and B alloyed Fe-22Cr ferritic steels for solid oxide fuel cell interconnects (United States)

    Swaminathan, Srinivasan; Ko, Yoon Seok; Lee, Young-Su; Kim, Dong-Ik


    Two Fe-22 wt% Cr ferritic stainless steels containing varying concentrations of La (0.14 or 0.52 wt%), Cu (0.17 or 1.74 wt%) and B (48 or 109 ppm) are investigated with respect to oxidation behavior and high temperature area specific resistance (ASR) of the surface oxide scales. To determine the oxidation resistance of developed steels, continuous isothermal oxidation is carried out at 800 °C in air, for 2000 h, and their thermally grown oxide scale is characterized using dynamic SIMS, SEM/EDX, XRD and GI-XRD techniques. To assess their electrical performance, the ASR measurement by four-point probe method is conducted at 800 °C in air, for 400 h. In higher La content steel, the La-oxides at the scale/alloy interface promotes the oxygen transport which resulted in sub-surface oxidation of Mn, Cr, Ti and Al. Moreover, the inward growth of oxides contributes to increase of Fe-Cr alloy protrusions within the scale, which reduced the ASR. In contrast, sub-surface oxidation is reduced in high Cu-alloyed steel by segregated Cu at the scale/alloy interface. Thus, addition of Cu is effective to oxidation resistance and also to better electrical performance. However, no obvious impact of B on the scale sequence and/or ASR is observed.

  3. Comportement des matériaux organiques vis-à-vis des carburants oxygénés The Behavior of Organic Materials with Regard to Oxygenated Fuels

    Directory of Open Access Journals (Sweden)

    Puisais M.


    Full Text Available Les incidences d'emploi des produits oxygénés dans les carburants ont été déterminées sur la tenue des principaux matériaux polymères utilisés dans les véhicules et les équipements de distribution. Des carburants renferment diverses teneurs en éthanol ou en méthanol, éventuellement en conjonction avec des co-solvants tels que le tertiobutanol ou un mélange acétonobutylique ont été examinés. Les méthodes d'essais appliquées ont permis de déterminer le comportement à long terme des matériaux au niveau de leur perméabilité, gonflement, vieillissement, fissuration sous contraintes, extraction et résistance à l'ozone. The effects of using oxygenated products in gasolines have been determined concerning the resistance of the leading polymer materials used in vehicles and distribution equipment. Fuels containing varying amounts of ethanol or methanol, possibly in conjunction with cosolvents such as tertiobutanol or a butanol-acetone mixture, have been examined. The test methods applied have determined the long-term behavior of materials with regard to their permeability, swelling, aging, stress cracking, extraction and ozone resistance.

  4. WC-CoCr coatings sprayed by high velocity oxygen-fuel (HVOF flame on AA7050 aluminum alloy: electrochemical behavior in 3.5% NaCl solution

    Directory of Open Access Journals (Sweden)

    Marina Magnani


    Full Text Available In the present work, the electrochemical behavior of WC-CoCr coatings with 10 (W10, 15 (W15 and 20 (W20 torch passes sprayed by High Velocity Oxygen-Fuel (HVOF flame on AA7050 aluminum alloy substrate, evaluated in 3.5% NaCl solution, were compared using open-circuit potential (E OC measurements, electrochemical impedance spectroscopy (EIS and polarization curves. The coating surfaces and their cross sections were characterized by X ray diffraction and the Rockwell-C hardness test, and also by optical (OM and scanning electron microscopy (SEM before and after the corrosion tests. The electrochemical data showed that sample W10 presented higher corrosion resistance than the others in chloride solutions. In some tests, aluminum salts on the coating surface were identified by EDS, indicating the corrosion of the substrate. And using aluminon, aluminum ions were detected and analyzing the surface via stereomicroscopy, hydrogen bubbles were observed, both showing that the electrolyte reached the substrate and galvanic corrosion possibly occurred. The physical characterization showed that sample W10 presented a lower number of cracks and pores, justifying its higher corrosion resistance.

  5. Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

    Directory of Open Access Journals (Sweden)

    Tianchen Li


    Full Text Available In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS and high-velocity oxy-fuel spraying (HVOF, respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

  6. Accelerations of {epsilon}+{alpha}{yields}{beta} transformation and sintering of iron silicide by addition of Pd; Pd tenka ni yoru keikatetsu no {epsilon}+{alpha}{yields}{beta} hentai to shoketsu no sokushin

    Energy Technology Data Exchange (ETDEWEB)

    Kato, M.; Yamamoto, N.; Takeda, T. [Isuzu Advanced Engineering Center Ltd., Kanagawa (Japan); Hayashi, K. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science


    FeSi2 ({beta} phase) semiconducting iron silicide, which is expected to be widely used as a thermoelectric material in high temperature environment, is formed below 1259K by the peritectoid reaction of FeSi ({epsilon}) and Fe2Si5 ({alpha}) two metallic phases. Because the transformation of {epsilon} + {alpha} {yields} {beta} caused by this peritectoid reaction occurs considerably slowly, the iron silicide material which is produced by sintering of the powder at temperatures above 1259K has to be isothermally heat-treated for at least 180ks at about 1120K after the sintering so that the transformation occurs completely. We have found that the transformation was drastically accelerated by the addition of a small amount of Pd in the same way as Cu; the isothermal heat-treatment time necessary for the completion of the transformation was reduced to about 1/60. The sintering time needed for the almost full densification of the powder by pressure DCL sintering (DCL; direct current loading) was also reduced. A hypothesis for the mechanisms was proposed. 15 refs., 7 figs., 2 tabs.

  7. Fuel dissipater for pressurized fuel cell generators (United States)

    Basel, Richard A.; King, John E.


    An apparatus and method are disclosed for eliminating the chemical energy of fuel remaining in a pressurized fuel cell generator (10) when the electrical power output of the fuel cell generator is terminated during transient operation, such as a shutdown; where, two electrically resistive elements (two of 28, 53, 54, 55) at least one of which is connected in parallel, in association with contactors (26, 57, 58, 59), a multi-point settable sensor relay (23) and a circuit breaker (24), are automatically connected across the fuel cell generator terminals (21, 22) at two or more contact points, in order to draw current, thereby depleting the fuel inventory in the generator.

  8. BISON Fuel Performance Analysis of IFA-796 Rod 3 & 4 and Investigation of the Impact of Fuel Creep

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, Brian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sweet, Ryan T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    In order to improve the accident tolerance of light water reactor (LWR) fuel, alternative cladding materials have been proposed to replace the currently used zirconium (Zr)-based alloys. Of these materials, there is a particular focus on iron-chromiumaluminum (FeCrAl) alloys because they exhibit slower oxidation kinetics in high-temperature steam than Zr-alloys. This should decrease the energy release due to oxidation and slow cladding consumption in the presence of high temperature steam. These alloys should also exhibit increased “coping time” in the event of an accident scenario by improving the mechanical performance at high temperatures, allowing greater flexibility to achieve core cooling. As a continuation of the development of these alloys, in-reactor irradiation testing of FeCrAl cladded fuel rods has started. In order to provide insight on the possible behavior of these fuel rods as they undergo irradiation in the Halden Boiling Water Reactor, engineering analysis has been performed using FeCrAl material models implemented into the BISON fuel performance code. This milestone report provides an update on the ongoing development of modeling capability to predict FeCrAl cladding fuel performance and to provide an early look at the possible behavior of planned in-reactor FeCrAl cladding experiments. In particular, this report consists of two separate analyses. The first analysis consists of fuel performance simulations of IFA-796 rod 4 and two segments of rod 3. These simulations utilize previously implemented material models for the C35M FeCrAl alloy and UO2 to provide a bounding behavior analysis corresponding to variation of the initial fuel cladding gap thickness within the fuel rod. The second analysis is an assessment of the fuel and cladding stress states after modification of the fuel creep model that is currently implemented in the BISON fuel performance code. Effects from modifying the fuel creep model were identified for the BISON simulations

  9. Predicting Argentine Jet Fuel Prices (United States)


    scope of this study, but an understanding of its consequences is necessary to understand in depth the oil market structure of the country. Some of... structural and data assumptions (Banks et al. 2004: 362). The first ones are related with the simplifications and abstraction inside the methodology used...Scheimberg Sebastian. “Comentario al trabajo de German Coloma: Analisys of the behavior of the Argentine fuel market”. Political Economy Asociation

  10. Multipoint Fuel Injection Arrangements (United States)

    Prociw, Lev Alexander (Inventor)


    A multipoint fuel injection system includes a plurality of fuel manifolds. Each manifold is in fluid communication with a plurality of injectors arranged circumferentially about a longitudinal axis for multipoint fuel injection. The injectors of separate respective manifolds are spaced radially apart from one another for separate radial staging of fuel flow to each respective manifold.

  11. Combustion characteristics of thermally stressed hydrocarbon fuels (United States)

    Curtis, Colin William

    Liquid propelled propulsion systems, which range from rocket systems to hypersonic scramjet and ramjet engines, require active cooling in order to prevent additional payload requirements. In these systems, the liquid fuel is used as a coolant and is delivered through micro-channels that surround the combustion chambers, nozzles, as well as the exterior surfaces in order to extract heat from these affected areas. During this process, heat exchange occurs through phase change, sensible heat extraction, and endothermic reactions experienced by the liquid fuel. Previous research has demonstrated the significant modifications in fuel composition and changes to the fuel's physical properties that can result from these endothermic reactions. As a next step, we are experimentally investigating the effect that endothermic reactions have on fundamental flame behavior for real hydrocarbon fuels that are used as rocket and jet propellants. To achieve this goal, we have developed a counter-flow flame burner to measure extinction limits of the thermally stressed fuels. The counter-flow flame system is to be coupled with a high pressure reactor, capable of subjecting the fuel to 170 atm and 873 K, effectively simulating the extreme environment that cause the liquid fuel to experience endothermic reactions. The fundamental flame properties of the reacted fuels will be compared to those of unreacted fuels, allowing us to determine the role of endothermic reactions on the combustion behavior of current hydrocarbon jet and rocket propellants. To quantify the change in transport properties and chemical kinetics of the reacting mixture, simultaneous numerical simulations of the reactor portion of the experiment coupled with a counterflow flame simulation are performed using n-heptane and n-dodecane.

  12. Analysis of hydrogen, carbon, sulfur and volatile compounds in (U{sub 3}Si{sub 2} - Al) nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Moura, Sergio C.; Redigolo, Marcelo M.; Amaral, Priscila O.; Leao, Claudio; Oliveira, Glaucia A.C. de; Bustillos, Oscar V., E-mail: [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)


    Uranium silicide U{sub 3}Si{sub 2} is used as nuclear fuel in the research nuclear reactor IEA-R1 at IPEN/CNEN, Sao Paulo, Brazil. The U{sub 3}Si{sub 2} is dispersed in aluminum reaching high densities of uranium in the nucleus of the fuel, up to 4.8 gU cm{sup -3}. This nuclear fuel must comply with a quality control, which includes analysis of hydrogen, carbon and sulfur for the U{sub 3}Si{sub 2} and volatile compound for the aluminum. Hydrogen, carbon and sulfur are analyzed by the method of Radio Frequency gas extraction combustion coupled with Infrared detector. Volatile compounds are analyzed by the method of heated gas extraction coupled with gravimetric measurement. These methods are recommended by the American Society for Testing Materials (ASTM) for nuclear materials. The average carbon and sulfur measurements are 30 μg g{sup -1} and 3 μg g{sup -1}, respectively, and 40 μg g{sup -1} for volatile compounds. The hydrogen analyzer is a TCHEN 600 LECO, carbon and sulfur analyzer is a CS 244 LECO and the volatile compounds analyzer is a home-made apparatus that use a resistant furnace, a gas pipe measurement and a glove-box with controlled atmosphere where an analytical balance has been installed, this analyzer was made at IPEN laboratory. (author)

  13. Effects of Fuel Quantity on Soot Formation Process for Biomass-Based Renewable Diesel Fuel Combustion

    KAUST Repository

    Jing, Wei


    Soot formation process was investigated for biomass-based renewable diesel fuel, such as biomass to liquid (BTL), and conventional diesel combustion under varied fuel quantities injected into a constant volume combustion chamber. Soot measurement was implemented by two-color pyrometry under quiescent type diesel engine conditions (1000 K and 21% O2 concentration). Different fuel quantities, which correspond to different injection widths from 0.5 ms to 2 ms under constant injection pressure (1000 bar), were used to simulate different loads in engines. For a given fuel, soot temperature and KL factor show a different trend at initial stage for different fuel quantities, where a higher soot temperature can be found in a small fuel quantity case but a higher KL factor is observed in a large fuel quantity case generally. Another difference occurs at the end of combustion due to the termination of fuel injection. Additionally, BTL flame has a lower soot temperature, especially under a larger fuel quantity (2 ms injection width). Meanwhile, average soot level is lower for BTL flame, especially under a lower fuel quantity (0.5 ms injection width). BTL shows an overall low sooting behavior with low soot temperature compared to diesel, however, trade-off between soot level and soot temperature needs to be carefully selected when different loads are used.

  14. Fuel transfer system (United States)

    Townsend, Harold E.; Barbanti, Giancarlo


    A nuclear fuel bundle fuel transfer system includes a transfer pool containing water at a level above a reactor core. A fuel transfer machine therein includes a carriage disposed in the transfer pool and under the water for transporting fuel bundles. The carriage is selectively movable through the water in the transfer pool and individual fuel bundles are carried vertically in the carriage. In a preferred embodiment, a first movable bridge is disposed over an upper pool containing the reactor core, and a second movable bridge is disposed over a fuel storage pool, with the transfer pool being disposed therebetween. A fuel bundle may be moved by the first bridge from the reactor core and loaded into the carriage which transports the fuel bundle to the second bridge which picks up the fuel bundle and carries it to the fuel storage pool.

  15. Microfluidic fuel cell systems (United States)

    Ho, Bernard; Kjeang, Erik


    A microfluidic fuel cell is a microfabricated device that produces electrical power through electrochemical reactions involving a fuel and an oxidant. Microfluidic fuel cell systems exploit co-laminar flow on the microscale to separate the fuel and oxidant species, in contrast to conventional fuel cells employing an ion exchange membrane for this function. Since 2002 when the first microfluidic fuel cell was invented, many different fuels, oxidants, and architectures have been investigated conceptually and experimentally. In this mini-review article, recent advancements in the field of microfluidic fuel cell systems are documented, with particular emphasis on design, operation, and performance. The present microfluidic fuel cell systems are categorized by the fluidic phases of the fuel and oxidant streams, featuring gaseous/gaseous, liquid/gaseous, and liquid/liquid systems. The typical cell configurations and recent contributions in each category are analyzed. Key research challenges and opportunities are highlighted and recommendations for further work are provided.

  16. Fuel cells seminar

    Energy Technology Data Exchange (ETDEWEB)



    This year`s meeting highlights the fact that fuel cells for both stationary and transportation applications have reached the dawn of commercialization. Sales of stationary fuel cells have grown steadily over the past 2 years. Phosphoric acid fuel cell buses have been demonstrated in urban areas. Proton-exchange membrane fuel cells are on the verge of revolutionizing the transportation industry. These activities and many more are discussed during this seminar, which provides a forum for people from the international fuel cell community engaged in a wide spectrum of fuel cell activities. Discussions addressing R&D of fuel cell technologies, manufacturing and marketing of fuel cells, and experiences of fuel cell users took place through oral and poster presentations. For the first time, the seminar included commercial exhibits, further evidence that commercial fuel cell technology has arrived. A total of 205 papers is included in this volume.

  17. Mathematical modeling of solid oxide fuel cells (United States)

    Lu, Cheng-Yi; Maloney, Thomas M.


    Development of predictive techniques, with regard to cell behavior, under various operating conditions is needed to improve cell performance, increase energy density, reduce manufacturing cost, and to broaden utilization of various fuels. Such technology would be especially beneficial for the solid oxide fuel cells (SOFC) at it early demonstration stage. The development of computer models to calculate the temperature, CD, reactant distributions in the tubular and monolithic SOFCs. Results indicate that problems of nonuniform heat generation and fuel gas depletion in the tubular cell module, and of size limitions in the monolithic (MOD 0) design may be encountered during FC operation.

  18. Alternate Fuels Combustion Research (United States)


    nozzle using a vernier e. take photographs of carbon accumulation Carbon deposition checks were done for all fifteen fuels with simplex nozzle and six... micrometer valve and open cooler valve - set fuel circuit to bypass mode - start fuel pump & close cooler valve until abotit 100 psi is indicated on the...cooler gauge - open micrometer valve to desired fuel flow - start main air and switch on the refrigeration unit - allow both the fuel and air systems to

  19. Materials for fuel cells


    Haile, Sossina M


    Because of their potential to reduce the environmental impact and geopolitical consequences of the use of fossil fuels, fuel cells have emerged as tantalizing alternatives to combustion engines. Like a combustion engine, a fuel cell uses some sort of chemical fuel as its energy source but, like a battery, the chemical energy is directly converted to electrical energy, without an often messy and relatively inefficient combustion step. In addition to high efficiency and low emissions, fuel cell...

  20. Hybrid Fuel Cell Systems


    Brouwer, J.; Samuelsen, GS


    Examples of hybrid fuel cell power generation cycles are the combine high-temperature fuel cells and gas turbines, reciprocating engines, or another fuel cell. These represent the hybrid power plants of the future. The conceptual systems have the potential to achieve efficiencies greater than 70 percent and be commercially ready by year 2010 or sooner. The hybrid fuel cell/turbine (FC/T) power plant will combine a high-temperature, conventional molten carbonate fuel cell (MCFC)...

  1. Spent fuel workshop'2002

    Energy Technology Data Exchange (ETDEWEB)

    Poinssot, Ch


    This document gathers the transparencies of the presentations given at the 2002 spent fuel workshop: Session 1 - Research Projects: Overview on the IN CAN PROCESSES European project (M. Cowper), Overview on the SPENT FUEL STABILITY European project (C. Poinssot), Overview on the French R and D project on spent fuel long term evolution, PRECCI (C. Poinssot); Session 2 - Spent Fuel Oxidation: Oxidation of uranium dioxide single crystals (F. Garrido), Experimental results on SF oxidation and new modeling approach (L. Desgranges), LWR spent fuel oxidation - effects of burn-up and humidity (B. Hanson), An approach to modeling CANDU fuel oxidation under dry storage conditions (P. Taylor); Session 3 - Spent Fuel Dissolution Experiments: Overview on high burnup spent fuel dissolution studies at FZK/INE (A. Loida), Results on the influence of hydrogen on spent fuel leaching (K. Spahiu), Leaching of spent UO{sub 2} fuel under inert and reducing conditions (Y. Albinsson), Fuel corrosion investigation by electrochemical techniques (D. Wegen), A reanalysis of LWR spent fuel flow through dissolution tests (B. Hanson), U-bearing secondary phases formed during fuel corrosion (R. Finch), The near-field chemical conditions and spent fuel leaching (D. Cui), The release of radionuclides from spent fuel in bentonite block (S.S. Kim), Trace actinide behavior in altered spent fuel (E. Buck, B. Hanson); Session 4 - Radiolysis Issues: The effect of radiolysis on UO{sub 2} dissolution determined from electrochemical experiments with {sup 238}Pu doped UO{sub 2} M. Stroess-Gascoyne (F. King, J.S. Betteridge, F. Garisto), doped UO{sub 2} studies (V. Rondinella), Preliminary results of static and dynamic dissolution tests with {alpha} doped UO{sub 2} in Boom clay conditions (K. Lemmens), Studies of the behavior of UO{sub 2} / water interfaces under He{sup 2+} beam (C. Corbel), Alpha and gamma radiolysis effects on UO{sub 2} alteration in water (C. Jegou), Behavior of Pu-doped pellets in brines

  2. Chemical compatibility between UO2 fuel and SiC cladding for LWRs. Application to ATF (Accident-Tolerant Fuels) (United States)

    Braun, James; Guéneau, Christine; Alpettaz, Thierry; Sauder, Cédric; Brackx, Emmanuelle; Domenger, Renaud; Gossé, Stéphane; Balbaud-Célérier, Fanny


    Silicon carbide-silicon carbide (SiC/SiC) composites are considered to replace the current zirconium-based cladding materials thanks to their good behavior under irradiation and their resistance under oxidative environments at high temperature. In the present work, a thermodynamic analysis of the UO2±x/SiC system is performed. Moreover, using two different experimental methods, the chemical compatibility of SiC towards uranium dioxide, with various oxygen contents (UO2±x) is investigated in the 1500-1970 K temperature range. The reaction leads to the formation of mainly uranium silicides and carbides phases along with CO and SiO gas release. Knudsen Cell Mass Spectrometry is used to measure the gas release occurring during the reaction between UO2+x and SiC powders as function of time and temperature. These experimental conditions are representative of an open system. Diffusion couple experiments with pellets are also performed to study the reaction kinetics in closed system conditions. In both cases, a limited chemical reaction is observed below 1700 K, whereas the reaction is enhanced at higher temperature due to the decomposition of SiC leading to Si vaporization. The temperature of formation of the liquid phase is found to lie between 1850 < T < 1950 K.

  3. Irradiation test plan of DUPIC fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Ki Kwang; Song, K. C.; Park, H. S. and others


    The objective of the irradiation test of DUPIC fuel at HANARO is to obtain the data of in-core behavior and evaluate the nuclear, thermal and mechanical performance of DUPIC fuel. The irradiation of DUPIC fuel will start at April 25, 2000 for about 2 months, and the burnup of 2,000 MWD/MTU will be attained for this period. The pre-irradiation examinations for DUPIC fuel, such as visual inspection, dimension measurement, He leak test and microstructure observation, was carried out. The post-irradiation examination items for the irradiated DUPIC fuel are planned to be the NDA test, visual inspection and dimension measurement, as well as the analyses for the fission gas release, the microstructure of pellets and the distribution and shape of imbedded nuclides. The DUPIC mini-elements were fabricated in the DFDF (IMEF M6 cell) using the G23-G2 rod. For the HANARO core calculation, the initial composition of DUPIC fuel was estimated using ORIGEN-2 code based on the burnup history of the G23-G2 rod. The design features of DUPIC pellets, the mini-element and the irradiation capsule, were supplemented considering the characteristics of DUPIC fuel and the results from the irradiation test of the simulated DUPIC fuel performed in 1999. The nuclear, thermohydraulic and mechanical characteristics of DUPIC fuel under the normal operation condition were evaluated for the safety analysis on the HANARO. Using these results, potential accidents initiated by DUPIC fuel were estimated, and Safety analyses on the locked rotor and RIA accidents were carried out in order to assess the integrity of DUPIC fuel under the accident condition initiated by the HANARO. Based on the results of these safety analyses, the supplemental countermeasures for securing the sufficient thermal margins were set up, as well. At the last, similar overseas and domestic cases were introduced.


    Energy Technology Data Exchange (ETDEWEB)

    N.E. Woolstenhulme; S.C. Taylor; G.A. Moore; D.M. Sterbentz


    Nuclear fuel is the core component of reactors that is used to produce the neutron flux required for irradiation research purposes as well as commercial power generation. The development of nuclear fuels with low enrichments of uranium is a major endeavor of the RERTR program. In the development of these fuels, the RERTR program uses nondestructive examination (NDE) techniques for the purpose of determining the properties of nuclear fuel plate experiments without imparting damage or altering the fuel specimens before they are irradiated in a reactor. The vast range of properties and information about the fuel plates that can be characterized using NDE makes them highly useful for quality assurance and for analyses used in modeling the behavior of the fuel while undergoing irradiation. NDE is also particularly useful for creating a control group for post-irradiation examination comparison. The two major categories of NDE discussed in this paper are X-ray radiography and ultrasonic testing (UT) inspection/evaluation. The radiographic scans are used for the characterization of fuel meat density and homogeneity as well as the determination of fuel location within the cladding. The UT scans are able to characterize indications such as voids, delaminations, inclusions, and other abnormalities in the fuel plates which are generally referred to as debonds as well as to determine the thickness of the cladding using ultrasonic acoustic microscopy methods. Additionally, the UT techniques are now also being applied to in-canal interim examination of fuel experiments undergoing irradiation and the mapping of the fuel plate surface profile to determine fuel swelling. The methods used to carry out these NDE techniques, as well as how they operate and function, are described along with a description of which properties are characterized.

  5. Fuel injector system (United States)

    Hsu, Bertrand D.; Leonard, Gary L.


    A fuel injection system particularly adapted for injecting coal slurry fuels at high pressures includes an accumulator-type fuel injector which utilizes high-pressure pilot fuel as a purging fluid to prevent hard particles in the fuel from impeding the opening and closing movement of a needle valve, and as a hydraulic medium to hold the needle valve in its closed position. A fluid passage in the injector delivers an appropriately small amount of the ignition-aiding pilot fuel to an appropriate region of a chamber in the injector's nozzle so that at the beginning of each injection interval the first stratum of fuel to be discharged consists essentially of pilot fuel and thereafter mostly slurry fuel is injected.

  6. Dual Tank Fuel System (United States)

    Wagner, Richard William; Burkhard, James Frank; Dauer, Kenneth John


    A dual tank fuel system has primary and secondary fuel tanks, with the primary tank including a filler pipe to receive fuel and a discharge line to deliver fuel to an engine, and with a balance pipe interconnecting the primary tank and the secondary tank. The balance pipe opens close to the bottom of each tank to direct fuel from the primary tank to the secondary tank as the primary tank is filled, and to direct fuel from the secondary tank to the primary tank as fuel is discharged from the primary tank through the discharge line. A vent line has branches connected to each tank to direct fuel vapor from the tanks as the tanks are filled, and to admit air to the tanks as fuel is delivered to the engine.

  7. Examination of physical properties of fuels and mixtures with alternative fuels (United States)

    Lown, Anne Lauren

    ABSTRACT. EXAMINATION OF PHYSICAL PROPERTIES OF FUELS AND MIXTURES WITH ALTERNATIVE FUELS. By. Anne Lauren Lown. The diversity of alternative fuels is increasing due to new second generation biofuels. By modeling alternative fuels and fuel mixtures, types of fuels can be selected based on their properties, without producing and testing large batches. A number of potential alternative fuels have been tested and modeled to determine their impact when blended with traditional diesel and jet fuels. The properties evaluated include cloud point and pour point temperature, cetane number, distillation curve, and speed of sound. This work represents a novel approach to evaluating the properties of alternative fuels and their mixtures with petroleum fuels. Low temperature properties were evaluated for twelve potential biofuel compounds in mixtures with three diesel fuels and one jet fuel. Functional groups tested included diesters, esters, ketones, and ethers, and alkanes were used for comparison. Alkanes, ethers, esters, and ketones with a low melting point temperature were found to decrease the fuel cloud point temperature. Diesters added to fuels display an upper critical solution temperature, and multiple methods were used to confirm the presence of liquid-liquid immiscibility. These behaviors are independent of chain length and branching, as long as the melting point temperature of the additive is not significantly higher than the cloud point temperature of the fuel. Physical properties were estimated for several potential fuel additive molecules using group contribution methods. Quantum chemical calculations were used for ideal gas heat capacities. Fuel surrogates for three petroleum based fuels and six alternative fuels were developed. The cloud point temperature, distillation curve, cetane number, and average molecular weight for different fuel surrogates were simultaneously represented. The proposed surrogates use the experimental mass fractions of paraffins, and

  8. Using a prescribed fire to test custom and standard fuel models for fire behaviour prediction in a non-native, grass-invaded tropical dry shrubland (United States)

    Andrew D. Pierce; Sierra McDaniel; Mark Wasser; Alison Ainsworth; Creighton M. Litton; Christian P. Giardina; Susan Cordell; Ralf Ohlemuller


    Questions: Do fuel models developed for North American fuel types accurately represent fuel beds found in grass-invaded tropical shrublands? Do standard or custom fuel models for firebehavior models with in situ or RAWS measured fuel moistures affect the accuracy of predicted fire behavior in grass-invaded tropical shrublands? Location: Hawai’i Volcanoes National...

  9. Advanced research reactor fuel development

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang Kyu; Pak, H. D.; Kim, K. H. [and others


    The fabrication technology of the U{sub 3}Si fuel dispersed in aluminum for the localization of HANARO driver fuel has been launches. The increase of production yield of LEU metal, the establishment of measurement method of homogeneity, and electron beam welding process were performed. Irradiation test under normal operation condition, had been carried out and any clues of the fuel assembly breakdown was not detected. The 2nd test fuel assembly has been irradiated at HANARO reactor since 17th June 1999. The quality assurance system has been re-established and the eddy current test technique has been developed. The irradiation test for U{sub 3}Si{sub 2} dispersed fuels at HANARO reactor has been carried out in order to compare the in-pile performance of between the two types of U{sub 3}Si{sub 2} fuels, prepared by both the atomization and comminution processes. KAERI has also conducted all safety-related works such as the design and the fabrication of irradiation rig, the analysis of irradiation behavior, thermal hydraulic characteristics, stress analysis for irradiation rig, and thermal analysis fuel plate, for the mini-plate prepared by international research cooperation being irradiated safely at HANARO. Pressure drop test, vibration test and endurance test were performed. The characterization on powders of U-(5.4 {approx} 10 wt%) Mo alloy depending on Mo content prepared by rotating disk centrifugal atomization process was carried out in order to investigate the phase stability of the atomized U-Mo alloy system. The {gamma}-U phase stability and the thermal compatibility of atomized U-16at.%Mo and U-14at.%Mo-2at.%X(: Ru, Os) dispersion fuel meats at an elevated temperature have been investigated. The volume increases of U-Mo compatibility specimens were almost the same as or smaller than those of U{sub 3}Si{sub 2}. However the atomized alloy fuel exhibited a better irradiation performance than the comminuted alloy. The RERTR-3 irradiation test of nano

  10. Mapping wildland fuels for fire management across multiple scales: integrating remote sensing, GIS, and biophysical modeling (United States)

    Keane, Robert E.; Burgan, Robert E.; Van Wagtendonk, Jan W.


    Fuel maps are essential for computing spatial fire hazard and risk and simulating fire growth and intensity across a landscape. However, fuel mapping is an extremely difficult and complex process requiring expertise in remotely sensed image classification, fire behavior, fuels modeling, ecology, and geographical information systems (GIS). This paper first presents the challenges of mapping fuels: canopy concealment, fuelbed complexity, fuel type diversity, fuel variability, and fuel model generalization. Then, four approaches to mapping fuels are discussed with examples provided from the literature: (1) field reconnaissance; (2) direct mapping methods; (3) indirect mapping methods; and (4) gradient modeling. A fuel mapping method is proposed that uses current remote sensing and image processing technology. Future fuel mapping needs are also discussed which include better field data and fuel models, accurate GIS reference layers, improved satellite imagery, and comprehensive ecosystem models.

  11. Construction of a four tip scanning tunneling microscope/scanning electron microscope combination and conductivity measurements of silicide nanowires; Aufbau einer Vierspitzen-Rastertunnelmikroskop/Rasterelektronenmikroskop-Kombination und Leitfaehigkeitsmessungen an Silizid Nanodraehten

    Energy Technology Data Exchange (ETDEWEB)

    Zubkov, Evgeniy


    In this work the combination of a four-tip scanning tunneling microscope with a scanning electron microscope is presented. By means of this apparatus it is possible to perform the conductivity measurements on the in-situ prepared nanostructures in ultra-high vacuum. With the aid of a scanning electron microscope (SEM), it becomes possible to position the tunneling tips of the four-tip scanning tunneling microscope (STM), so that an arrangement for a four-point probe measurement on nanostructures can be obtained. The STM head was built according to the novel coaxial Beetle concept. This concept allows on the one hand, a very compact arrangement of the components of the STM and on the other hand, the new-built STM head has a good mechanical stability, in order to achieve atomic resolution with all four STM units. The atomic resolution of the STM units was confirmed by scanning a Si(111)-7 x 7 surface. The thermal drift during the STM operation, as well as the resonant frequencies of the mechanical structure of the STM head, were determined. The scanning electron microscope allows the precise and safe navigation of the tunneling tips on the sample surface. Multi tip spectroscopy with up to four STM units can be performed synchronously. To demonstrate the capabilities of the new-built apparatus the conductivity measurements were carried out on metallic yttrium silicide nanowires. The nanowires were prepared by the in-situ deposition of yttrium on a heated Si(110) sample surface. Current-voltage curves were recorded on the nanowires and on the wetting layer in-between. The curves indicate an existence of the Schottky barrier between the yttrium silicide nanowires and the silicon bulk. By means of the two-tip measurements with a gate, the insulating property of the Schottky barrier has been confirmed. Using this Schottky barrier, it is possible to limit the current to the nanowire and to prevent it from flowing through the silicon bulk. A four-tip resistance measurement

  12. Small Volume Fuel Testers Report

    Energy Technology Data Exchange (ETDEWEB)

    Schoegl, I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McNenly, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Killingsworth, N. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Micro-liter fuel ignition testing (μ-FIT) is based on the premise that characteristics FREI (Flames with Repetitive Extinction and Ignition, i.e. cyclically occurring combustion events within heated capillaries), are linked to fuel properties. In early FY16, proof-of-concept measurements with primary reference fuel (PRF) mixtures, i.e. blends of n-heptane and iso-octane, yielded clear evidence for the feasibility of the approach. Our experiments showed that it is critical to accurately link observed flame positions to local temperatures, which provides information on ignition, extinction and flame propagation, all of which are known to be impacted by fuel properties. In FY16, one major hurdle was uncertainty of temperature calibration, which required significant efforts for corrective action that were not included in the original scope of work. Temperature calibrations are obtained by translating a thermocouple within the capillary in absence of a flame. While measurements have good repeatability when accounting for transient and insertion effects, results from nominally identical thermocouples reveal unacceptable uncertainty (up to ±50K), which is attributed to variations in thermocouple placement and manufacturing tolerances. This issue is currently being resolved by switching to non-intrusive optical temperature measurements. Updates are expected to yield uncertainties of less than ±10K, while also eliminating transient and insertion effects. The experimental work was complemented by computational efforts where it was shown that a simplified Lagrangian zero-D model with detailed kinetics yields fuelspecific differentiation of ignition temperatures for simple fuels that are consistent with experiments. Further, a 2D transient model was implemented in OpenFOAM to investigate combustion behavior of simple fuels at elevated pressure. In an upcoming visit to LLNL, more advanced simulations using LLNL’s computational tools (e.g. zero-RK) are planned, which will

  13. Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesan, Krishna


    The purpose of this program was to develop low-emissions, efficient fuel-flexible combustion technology which enables operation of a given gas turbine on a wider range of opportunity fuels that lie outside of current natural gas-centered fuel specifications. The program encompasses a selection of important, representative fuels of opportunity for gas turbines with widely varying fundamental properties of combustion. The research program covers conceptual and detailed combustor design, fabrication, and testing of retrofitable and/or novel fuel-flexible gas turbine combustor hardware, specifically advanced fuel nozzle technology, at full-scale gas turbine combustor conditions. This project was performed over the period of October 2008 through September 2011 under Cooperative Agreement DE-FC26-08NT05868 for the U.S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled "Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines". The overall objective of this program was met with great success. GE was able to successfully demonstrate the operability of two fuel-flexible combustion nozzles over a wide range of opportunity fuels at heavy-duty gas turbine conditions while meeting emissions goals. The GE MS6000B ("6B") gas turbine engine was chosen as the target platform for new fuel-flexible premixer development. Comprehensive conceptual design and analysis of new fuel-flexible premixing nozzles were undertaken. Gas turbine cycle models and detailed flow network models of the combustor provide the premixer conditions (temperature, pressure, pressure drops, velocities, and air flow splits) and illustrate the impact of widely varying fuel flow rates on the combustor. Detailed chemical kinetic mechanisms were employed to compare some fundamental combustion characteristics of the target fuels, including flame speeds and lean blow-out behavior. Perfectly premixed combustion experiments were conducted to

  14. 77 FR 699 - Regulation of Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel... (United States)


    ... January 5, 2012 Part V Environmental Protection Agency 40 CFR Part 80 Regulation of Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel Pathways Under the Renewable Fuel Standard... Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel Pathways Under the...

  15. Influence of Compression Ratio on High Load Performance and Knock Behavior for Gasoline Port-Fuel Injection, Natural Gas Direct Injection and Blended Operation in a Spark Ignition Engine

    Energy Technology Data Exchange (ETDEWEB)

    Pamminger, Michael; Sevik, James; Scarcelli, Riccardo; Wallner, Thomas; Hall, Carrie


    Natural Gas (NG) is an alternative fuel which has attracted a lot of attention recently, in particular in the US due to shale gas availability. The higher hydrogen-to-carbon (H/C) ratio, compared to gasoline, allows for decreasing carbon dioxide emissions throughout the entire engine map. Furthermore, the high knock resistance of NG allows increasing the efficiency at high engine loads compared to fuels with lower knock resistance. NG direct injection (DI) allows for fuel to be added after intake valve closing (IVC) resulting in an increase in power density compared to an injection before IVC. Steady-state engine tests were performed on a single-cylinder research engine equipped with gasoline (E10) port-fuel injection (PFI) and NG DI to allow for in-cylinder blending of both fuels. Knock investigations were performed at two discrete compression ratios (CR), 10.5 and 12.5. Operating conditions span mid-load, wide-open-throttle and boosted conditions, depending on the knock response of the fuel blend. Blended operation was performed using E10 gasoline and NG. An additional gasoline type fuel (E85) with higher knock resistance than E10 was used as a high-octane reference fuel, since the octane rating of E10-NG fuel blends is unknown. Spark timing was varied at different loads under stoichiometric conditions in order to study the knock response as well as the effects on performance and efficiency. As anticipated, results suggest that the knock resistance can be increased significantly by increasing the NG amount. Comparing the engine operation with the least knock resistant fuel, E10 PFI, and the fuel blend with the highest knock resistance, 75% NG DI, shows an increase in indicated mean effective pressure of about 9 bar at CR 12.5. The usage of reference fuels with known knock characteristics allowed an assessment of knock characteristic of intermediate E10-NG blend levels. Mathematical correlations were developed allowing characterizing the occurrence of knocking

  16. Visual Assessment of Surface Fuel Loads Does Not Align with Destructively Sampled Surface Fuels

    Directory of Open Access Journals (Sweden)

    Sarah C. McColl-Gausden


    Full Text Available Fuel load and structure are fundamental drivers of fire behaviour. Accurate data is required for managers and researchers to better understand our ability to alter fire risk. While there are many ways to quantify fuel, visual assessment methods are generally considered the most efficient. Visual hazard assessments are commonly used by managers, government agencies and consultants to provide a fuel hazard score or rating but not a quantity of fuel. Many systems attempt to convert the hazard score or rating to a fuel load for use in fire behaviour models. Here we investigate whether the conversion table in the widely used Overall Fuel Hazard Guide (OFHG matches destructively sampled fuel loads from 116 sites across five forest types. We specifically examine whether there are quantifiable differences that can be attributed to forest type. We found there is overlap between the two methods for low, moderate and high hazard categories, however for the very high and extreme hazard categories, visual assessment overestimated fuel load in four of the five forest types. Using a commonly applied fire behaviour model, we found that the overestimation of fuel load in very high and extreme hazard categories leads to an overestimation of fire behavior in these hazard categories.

  17. DUPIC fuel compatibility assessment

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hang Bok; Rho, G. H.; Park, J. W. [and others


    The purpose of this study is to assess the compatibility of DUPIC(Direct Use of Spent PWR Fuel in CANDU Reactors) fuel with the current CANDU 6 reactor, which is one of the technology being developed to utilize the spent PWR fuel in CANDU reactors. The phase 1 study of this project includes the feasibility analysis on applicability of the current core design method, the feasibility analysis on operation of the DUPIC fuel core, the compatibility analysis on individual reactor system, the sensitivity analysis on the fuel composition, and the economic analysis on DUPIC fuel cycle. The results of the validation calculations have confirmed that the current core analysis system is acceptable for the feasibility study of the DUPIC fuel compatibility analysis. The results of core simulations have shown that both natural uranium and DUPIC fuel cores are almost the same from the viewpoint of the operational performance. For individual reactor system including reactively devices, the functional requirements of each system are satisfied in general. However, because of the pronounced power flattening in the DUPIC core, the radiation damage on the critical components increases, which should be investigated more in the future. The DUPIC fuel composition heterogeneity dose not to impose any serious effect on the reactor operation if the fuel composition is adjusted. The economics analysis has been performed through conceptual design studies on the DUPIC fuel fabrication, fuel handling in a plant, and spent fuel disposal, which has shown that the DUPIC fuel cycle is comparable to the once-trough fuel cycle considering uncertainties associated with unit costs of the fuel cycle components. The results of Phase 1 study have shown that it is feasible to use the DUPIC fuel in CANDU reactors without major changes in hardware. However further studies are required to confirm the safety of the reactor under accident condition.

  18. Study of the neutronic behavior of a fuel assembly with gadolinium of a reactor HPLWR; Estudio del comportamiento neutronico de un ensamble combustible con gadolinia de un reactor HPLWR

    Energy Technology Data Exchange (ETDEWEB)

    Barragan M, A.; Martin del Campo M, C.; Francois L, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Espinosa P, G., E-mail: [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)


    This work presents a neutronic study of a square assembly design of double line of fuel rods, with moderator box to center of the arrangement, for the nuclear reactor cooled with supercritical water, High Performance Light Water Reactor (HPLWR). For the fuel analyses of the reactor HPLWR the neutronic code Helios-2 was used, settling down as the first study on fuel under conditions of supercritical water that has been simulated with this code. The analyzed variables, essentials in the neutronic design of any reactor, were the infinite neutrons multiplication factor (k{infinity}) and the maximum power peaking factor (PPF{sub max}), as well as the reactivity coefficients by the fuel temperature. The k{infinity} and PPF{sub max} values were obtained under conditions in cold (293.6 K) and in hot (to 880.8 K). The tests were realized for a reference fuel assembly design, with 40 fuel rods with enrichments of 4 and 5% of U-235, and considering different concentrations of consumable poison (gadolinium - Gd{sub 2O3}) in some rods of the same assembly. The obtained results show values k{infinity} and PPF{sub max} minors to the present in the conventional light water reactors. Moreover, the reactivity coefficients by fuel temperature were verified with the purpose of satisfying the safety conditions required in the nuclear reactors. (Author)

  19. Thermal outgassing of irradiated nuclear fuel: a literature review

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, L.G.; Matsuzaki, C.L.; Burger, L.L.; Bray, L.A.


    An experimental program at PNL examined the release of volatile and semivolatile radionuclides from irradiated nuclear fuel under different modes of heat treatment. In support of this work, a literature evaluation was conducted to review the information on: physical changes in fuel and cladding; distribution, migration, and reactions of fission products; and theoretical studies. Omitted from the review are evaluations of various fission gas bubble behavior - swelling models. The different computer codes that have been used to predict fuel behavior are also not included. A large amount of work has been done on the behavior of nuclear fuels during irradiation. The goals of this work have been to ensure acceptable mechanical performance, provide safe operation, and assist in fuel design, preparation, and recycle. Many fundamental studies, including diffusion and lattice structures, are also reported. 51 references, 17 figures, 8 tables.

  20. Oxy-fuel combustion of pulverized fuels

    DEFF Research Database (Denmark)

    Yin, Chungen; Yan, Jinyue


    Oxy-fuel combustion of pulverized fuels (PF), as a promising technology for CO2 capture from power plants, has gained a lot of concerns and also advanced considerable research, development and demonstration in the last past years worldwide. The use of CO2 or the mixture of CO2 and H2O vapor as th...

  1. Fuel cells and fuel cell catalysts (United States)

    Masel, Richard I.; Rice, Cynthia A.; Waszczuk, Piotr; Wieckowski, Andrzej


    A direct organic fuel cell includes a formic acid fuel solution having between about 10% and about 95% formic acid. The formic acid is oxidized at an anode. The anode may include a Pt/Pd catalyst that promotes the direct oxidation of the formic acid via a direct reaction path that does not include formation of a CO intermediate.

  2. Experimental study of cell reversal of a high temperature polymer electrolyte membrane fuel cell caused by H2 starvation

    DEFF Research Database (Denmark)

    Zhou, Fan; Andreasen, Søren Juhl; Kær, Søren Knudsen


    Operation under fuel starvation has been proved to be harmful to the fuel cell by causing severe and irreversible degradation. To characterize the behaviors of the high temperature PEM fuel cell under fuel starvation conditions, the cell voltage and local current density is measured simultaneousl...

  3. Fuel droplet combustion. [ignition via shock wave shattering (United States)

    Kauffman, C. W.; Wierzba, A. S.; Nicholls, J. A.


    An analytical model is developed that demonstrates the behavior of fuel drop ignition, and experimental results are presented that describe the effect of aerodynamic shattering on the process of fuel drop ignition. It is shown that the explosive ignition of a fuel drop which interacts with a shock wave in an oxidizing atmosphere depends upon the production of a fuel-oxidizer mixture in the wake of the original drop. The creation of this mixture is dependent on the formation of fine spray as a result of the aerodynamic shattering of the original fuel drop, the evaporation of the fine spray, and the mixing of the fuel vapor with the surrounding hot oxidizer. Only then does the explosive ignition occur as a result of the chemical reaction between the gaseous fuel and oxidizer.

  4. MARMOT update for oxide fuel modeling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, Daniel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chakraborty, Pritam [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, Chao [Idaho National Lab. (INL), Idaho Falls, ID (United States); Aagesen, Larry [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ahmed, Karim [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, Wen [Idaho National Lab. (INL), Idaho Falls, ID (United States); Biner, Bulent [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bai, Xianming [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Tonks, Michael [Pennsylvania State Univ., University Park, PA (United States); Millett, Paul [Univ. of Arkansas, Fayetteville, AR (United States)


    This report summarizes the lower-length-scale research and development progresses in FY16 at Idaho National Laboratory in developing mechanistic materials models for oxide fuels, in parallel to the development of the MARMOT code which will be summarized in a separate report. This effort is a critical component of the microstructure based fuel performance modeling approach, supported by the Fuels Product Line in the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. The progresses can be classified into three categories: 1) development of materials models to be used in engineering scale fuel performance modeling regarding the effect of lattice defects on thermal conductivity, 2) development of modeling capabilities for mesoscale fuel behaviors including stage-3 gas release, grain growth, high burn-up structure, fracture and creep, and 3) improved understanding in material science by calculating the anisotropic grain boundary energies in UO$_2$ and obtaining thermodynamic data for solid fission products. Many of these topics are still under active development. They are updated in the report with proper amount of details. For some topics, separate reports are generated in parallel and so stated in the text. The accomplishments have led to better understanding of fuel behaviors and enhance capability of the MOOSE-BISON-MARMOT toolkit.

  5. Liquid fuel cells

    National Research Council Canada - National Science Library

    Soloveichik, Grigorii L


    The advantages of liquid fuel cells (LFCs) over conventional hydrogen-oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety...

  6. Nuclear fuel element (United States)

    Zocher, Roy W.


    A nuclear fuel element and a method of manufacturing the element. The fuel element is comprised of a metal primary container and a fuel pellet which is located inside it and which is often fragmented. The primary container is subjected to elevated pressure and temperature to deform the container such that the container conforms to the fuel pellet, that is, such that the container is in substantial contact with the surface of the pellet. This conformance eliminates clearances which permit rubbing together of fuel pellet fragments and rubbing of fuel pellet fragments against the container, thus reducing the amount of dust inside the fuel container and the amount of dust which may escape in the event of container breach. Also, as a result of the inventive method, fuel pellet fragments tend to adhere to one another to form a coherent non-fragmented mass; this reduces the tendency of a fragment to pierce the container in the event of impact.

  7. Logistic Fuel Processor Development

    National Research Council Canada - National Science Library

    Salavani, Reza


    ... to light gases then steam reform the light gases into hydrogen rich stream. This report documents the efforts in developing a fuel processor capable of providing hydrogen to a 3kW fuel cell stack...

  8. Automotive fuel economy program (United States)


    The Automotive Fuel Economy Program Annual Update summarizes the fuel economy performance of the vehicle fleet and the activities of the National Highway Traffic Safety Administration (NHTSA) during 2001. Included in this report is a section summariz...

  9. Bluff Body Fuel Mixer (United States)

    Cheung, Albert K. (Inventor); Hoke, James B. (Inventor); McKinney, Randal G. (Inventor)


    A combustor is provided. The combustor may include an axial fuel injection system, and a radial fuel injection system aft of the axial fuel injection system. The axial fuel injection system includes a mixer having a bluff body at an exit port of the mixer, and a fuel injector disposed within the mixer. A fuel and air mixer is also provided and comprises an outer housing with an exit port and a bluff body. The bluff body extends across the exit port of the outer housing. A fuel injection system is also provided. The systems comprise a mixer having a bluff body at an exit port of the mixer and a fuel injector disposed within the mixer.

  10. Direct hydrocarbon fuel cells (United States)

    Barnett, Scott A.; Lai, Tammy; Liu, Jiang


    The direct electrochemical oxidation of hydrocarbons in solid oxide fuel cells, to generate greater power densities at lower temperatures without carbon deposition. The performance obtained is comparable to that of fuel cells used for hydrogen, and is achieved by using novel anode composites at low operating temperatures. Such solid oxide fuel cells, regardless of fuel source or operation, can be configured advantageously using the structural geometries of this invention.

  11. Hydrogen Fuel Cell Vehicles


    Delucchi, Mark


    Hydrogen is an especially attractive transportation fuel. It is the least polluting fuel available, and can be produced anywhere there is water and a clean source of electricity. A fuel cycle in which hydrogen is produced by solar-electrolysis of water, or by gasification of renewably grown biomass, and then used in a fuel-cell powered electric-motor vehicle (FCEV), would produce little or no local, regional, or global pollution. Hydrogen FCEVs would combine the best features of bat...

  12. Cell module and fuel conditioner (United States)

    Hoover, D. Q., Jr.


    The computer code for the detailed analytical model of the MK-2 stacks is described. An ERC proprietary matrix is incorporated in the stacks. The mechanical behavior of the stack during thermal cycles under compression was determined. A 5 cell stack of the MK-2 design was fabricated and tested. Designs for the next three stacks were selected and component fabrication initiated. A 3 cell stack which verified the use of wet assembly and a new acid fill procedure were fabricated and tested. Components for the 2 kW test facility were received or fabricated and construction of the facility is underway. The definition of fuel and water is used in a study of the fuel conditioning subsystem. Kinetic data on several catalysts, both crushed and pellets, was obtained in the differential reactor. A preliminary definition of the equipment requirements for treating tap and recovered water was developed.

  13. Cell module and fuel conditioner (United States)

    Hoover, D. Q., Jr.


    The computer code for the detailed analytical model of the MK-2 stacks is described. An ERC proprietary matrix is incorporated in the stacks. The mechanical behavior of the stack during thermal cycles under compression was determined. A 5 cell stack of the MK-2 design was fabricated and tested. Designs for the next three stacks were selected and component fabrication initiated. A 3 cell stack which verified the use of wet assembly and a new acid fill procedure were fabricated and tested. Components for the 2 kW test facility were received or fabricated and construction of the facility is underway. The definition of fuel and water is used in a study of the fuel conditioning subsystem. Kinetic data on several catalysts, both crushed and pellets, was obtained in the differential reactor. A preliminary definition of the equipment requirements for treating tap and recovered water was developed.

  14. Ecological risk assessment to support fuels treatment project decisions (United States)

    Jay O' Laughlin


    Risk is a combined statement of the probability that something of value will be damaged and some measure of the damage’s adverse effect. Wildfires burning in the uncharacteristic fuel conditions now typical throughout the Western United States can damage ecosystems and adversely affect environmental conditions. Wildfire behavior can be modified by prefire fuel...

  15. Studies of valence of selected rare earth silicides determined using Si K and Pd/Rh L{sub 2,3} XANES and LAPW numerical studies

    Energy Technology Data Exchange (ETDEWEB)

    Zajdel, P., E-mail: [Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice (Poland); Kisiel, A., E-mail: [M. Smoluchowski Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30-348 Kraków (Poland); Szytuła, A., E-mail: [M. Smoluchowski Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30-348 Kraków (Poland); Goraus, J., E-mail: [Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice (Poland); Balerna, A., E-mail: [Laboratori Nazionali di Frascati, INFN, Lab DAPHINE-Light, Via E. Fermi 40, I-00044 Frascati (Italy); Banaś, A., E-mail: [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Starowicz, P., E-mail: [M. Smoluchowski Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30-348 Kraków (Poland); Konior, J., E-mail: [M. Smoluchowski Institute of Physics, Jagiellonian University, ul. Lojasiewicza 11, 30-348 Kraków (Poland); Cinque, G., E-mail: [Diamond Light Source, Harwell Campus, OX11 0DE Chilton-Didcot (United Kingdom); Grilli, A., E-mail: [Laboratori Nazionali di Frascati, INFN, Lab DAPHINE-Light, Via E. Fermi 40, I-00044 Frascati (Italy)


    Highlights: • The Si K and Pd L{sub 3} edges of R{sub 2}PdSi{sub 3} (R = Ce, Nd, Tb, Dy, Ho, Er) and HoRh{sub 2−x}Pd{sub x}Si{sub 2} are reported. • The R–Si bonds possess polar and 4d5s bands of Pd and Rh metallic characters. • There is no indication of Ce having a different valence than the other rare earths. • The positions and features of the calculated edges exhibit a fair agreement up to ≈10 eV. • The supercell used for Ho{sub 2}PdSi{sub 3} is good enough to reproduce the Si K edge. - Abstract: We report on the investigation of Si and Pd/Rh chemical environments using X-ray Absorption Near Edge Spectroscopy in two different families of rare earth silicides R{sub 2}PdSi{sub 3} (R = Ce, Nd, Tb, Dy, Ho, Er) and HoRh{sub 2−x}Pd{sub x}Si{sub 2} (x = 0, 0.5, 0.75, 1.0, 1.5, 1.8, 2.0). The Si K, Pd L{sub 3} and Rh L{sub 3} absorption edges were recorded in order to follow their changes upon the variation of 4f and 4d5s electron numbers. In both cases it was found that the Si K edge was shifted ≈0.5 eV toward lower energies, relative to pure silicon. In the first family, the shift decreases with increasing number of f-electrons, while the Si K edge remains constant upon rhodium–palladium substitution. In all cases the Pd L{sub 3} edge was shifted to higher energies relative to metallic Pd. No visible change in the Pd L{sub 3} position was observed either with a varying 4f electron count or upon Pd/Rh substitution. Also, the Rh L{sub 3} edge did not change. For two selected members, Ho{sub 2}PdSi{sub 3} and HoPd{sub 2}Si{sub 2}, the Wien2K’09 (LDA + U) package was used to calculate the electronic structure and the absorption edges. Si K edges were reproduced well for both compounds, while Pd L{sub 3} only exhibited a fair agreement for the second compound. This discrepancy between the Pd L{sub 3} theory and experiment for the Ho{sub 2}PdSi{sub 3} sample can be attributed to the specific ordered superstructure used in the numerical calculations

  16. Nontoxic Ionic Liquid Fuels for Exploration Applications (United States)

    Coil, Millicent


    The toxicity of propellants used in conventional propulsion systems increases not only safety risks to personnel but also costs, due to special handling required during the entire lifetime of the propellants. Orbital Technologies Corporation (ORBITEC) has developed and tested novel nontoxic ionic liquid fuels for propulsion applications. In Phase I of the project, the company demonstrated the feasibility of several ionic liquid formulations that equaled the performance of conventional rocket propellant monomethylhydrazine (MMH) and also provided low volatility and low toxicity. In Phase II, ORBITEC refined the formulations, conducted material property tests, and investigated combustion behavior in droplet and microreactor experiments. The company also explored the effect of injector design on performance and demonstrated the fuels in a small-scale thruster. The ultimate goal is to replace propellants such as MMH with fuels that are simultaneously high-performance and nontoxic. The fuels will have uses in NASA's propulsion applications and also in a range of military and commercial functions.

  17. Future Transient Testing of Advanced Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Jon Carmack


    The transient in-reactor fuels testing workshop was held on May 4–5, 2009 at Idaho National Laboratory. The purpose of this meeting was to provide a forum where technical experts in transient testing of nuclear fuels could meet directly with technical instrumentation experts and nuclear fuel modeling and simulation experts to discuss needed advancements in transient testing to support a basic understanding of nuclear fuel behavior under off-normal conditions. The workshop was attended by representatives from Commissariat à l'Énergie Atomique CEA, Japanese Atomic Energy Agency (JAEA), Department of Energy (DOE), AREVA, General Electric – Global Nuclear Fuels (GE-GNF), Westinghouse, Electric Power Research Institute (EPRI), universities, and several DOE national laboratories. Transient testing of fuels and materials generates information required for advanced fuels in future nuclear power plants. Future nuclear power plants will rely heavily on advanced computer modeling and simulation that describes fuel behavior under off-normal conditions. TREAT is an ideal facility for this testing because of its flexibility, proven operation and material condition. The opportunity exists to develop advanced instrumentation and data collection that can support modeling and simulation needs much better than was possible in the past. In order to take advantage of these opportunities, test programs must be carefully designed to yield basic information to support modeling before conducting integral performance tests. An early start of TREAT and operation at low power would provide significant dividends in training, development of instrumentation, and checkout of reactor systems. Early start of TREAT (2015) is needed to support the requirements of potential users of TREAT and include the testing of full length fuel irradiated in the FFTF reactor. The capabilities provided by TREAT are needed for the development of nuclear power and the following benefits will be realized by

  18. The investigation of effects specific fuel comsumption and emissions fuel mixtures nitromethane

    Directory of Open Access Journals (Sweden)

    Samet Çelebi


    Full Text Available In this study, changes of specific fuel consumption and exhaust emmission values of chemical produced nitromethane are compared with values of gasoline fuel. In motor tests conducted at full load, gasoline mixture including % 5 nitromethane yield decreased specific fuel consumption value of 3200 min-1 and low engine speed of % 6,18 percentage. On the other hand, engine power is increased. While CO and HC emissions were observed to be less than gasoline, CO2 and NOx emissions remained to be increased. In performed tests, it is also observed that when mixing nitromethane with % 10 more gasoline, over knocking and unstable motor behavior is observed.

  19. Generation of a global fuel data set using the Fuel Characteristic Classification System (United States)

    Lucrecia Pettinari, M.; Chuvieco, Emilio


    This study presents the methods for the generation of the first global fuel data set, containing all the parameters required to be input in the Fuel Characteristic Classification System (FCCS). The data set was developed from different spatial variables, both based on satellite Earth observation products and fuel databases, and is comprised by a global fuelbed map and a database that includes the parameters of each fuelbed that affect fire behavior and effects. A total of 274 fuelbeds were created and parameterized, and can be input into FCCS to obtain fire potentials, surface fire behavior and carbon biomass for each fuelbed. We present a first assessment of the fuel data set by comparing the carbon biomass obtained from our FCCS fuelbeds with the average biome values of four other regional or global biomass products. The results showed a good agreement both in terms of geographical distribution and biomass loads when compared to other biomass data, with the best results found for tropical and boreal forests (Spearman's coefficient of 0.79 and 0.77). This global fuel data set may be used for a varied range of applications, including fire danger assessment, fire behavior estimations, fuel consumption calculations and emissions inventories.

  20. Metal silicides with energetic pulses (United States)

    D'Anna, E.; Leggieri, G.; Luches, A.; Majni, G.; Nava, F.; Ottaviani, G.


    Samples formed of a thin metal film deposited on silicon single crystal were annealed with electron and laser (ruby and excimer) pulses over a wide range of fluences. From a comparison of the experimental results with the temperature profiles of the irradiated samples, it turns out that suicide formation starts when the metal/silicon interface reaches the lowest eutectic temperature of the binary metal/silicon system. The growth rate of reacted layers is of the order of 1 m/s.

  1. Neutronic fuel element fabrication (United States)

    Korton, George


    This disclosure describes a method for metallurgically bonding a complete leak-tight enclosure to a matrix-type fuel element penetrated longitudinally by a multiplicity of coolant channels. Coolant tubes containing solid filler pins are disposed in the coolant channels. A leak-tight metal enclosure is then formed about the entire assembly of fuel matrix, coolant tubes and pins. The completely enclosed and sealed assembly is exposed to a high temperature and pressure gas environment to effect a metallurgical bond between all contacting surfaces therein. The ends of the assembly are then machined away to expose the pin ends which are chemically leached from the coolant tubes to leave the coolant tubes with internal coolant passageways. The invention described herein was made in the course of, or under, a contract with the U.S. Atomic Energy Commission. It relates generally to fuel elements for neutronic reactors and more particularly to a method for providing a leak-tight metal enclosure for a high-performance matrix-type fuel element penetrated longitudinally by a multiplicity of coolant tubes. The planned utilization of nuclear energy in high-performance, compact-propulsion and mobile power-generation systems has necessitated the development of fuel elements capable of operating at high power densities. High power densities in turn require fuel elements having high thermal conductivities and good fuel retention capabilities at high temperatures. A metal clad fuel element containing a ceramic phase of fuel intimately mixed with and bonded to a continuous refractory metal matrix has been found to satisfy the above requirements. Metal coolant tubes penetrate the matrix to afford internal cooling to the fuel element while providing positive fuel retention and containment of fission products generated within the fuel matrix. Metal header plates are bonded to the coolant tubes at each end of the fuel element and a metal cladding or can completes the fuel-matrix enclosure

  2. Fuel loads and fuel type mapping (United States)

    Chuvieco, Emilio; Riaño, David; Van Wagtendonk, Jan W.; Morsdof, Felix; Chuvieco, Emilio


    Correct description of fuel properties is critical to improve fire danger assessment and fire behaviour modeling, since they guide both fire ignition and fire propagation. This chapter deals with properties of fuel that can be considered static in short periods of time: biomass loads, plant geometry, compactness, etc. Mapping these properties require a detail knowledge of vegetation vertical and horizontal structure. Several systems to classify the great diversity of vegetation characteristics in few fuel types are described, as well as methods for mapping them with special emphasis on those based on remote sensing images.

  3. Characterizing fuels in the 21st century. (United States)

    David Sandberg; Roger D. Ottmar; Geoffrey H. Cushon


    The ongoing development of sophisticated fire behavior and effects models has demonstrated the need for a comprehensive system of fuel classification that more accurately captures the structural complexity and geographic diversity of fuelbeds. The Fire and Environmental Research Applications Team (FERA) of the USD Forest Service, Pacific Northwest Research Station, is...

  4. Development of Metallic Fuels for Actinide Transmutation

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, Steven Lowe [Idaho National Laboratory; Fielding, Randall Sidney [Idaho National Laboratory; Benson, Michael Timothy [Idaho National Laboratory; Chichester, Heather Jean MacLean [Idaho National Laboratory; Carmack, William Jonathan [Idaho National Laboratory


    and 60%. In general, the performance of all of these substantially disparate metallic fuel alloys has been observed to be excellent, and their irradiation behaviors are generally consistent with historic norms for metallic fuels without minor actinide additions and having lower Pu or Zr contents. Future work is being undertaken with a view toward increasing the burnup potential of metallic fuels even more. Design innovations under investigation include: 1) lowering the fuel smear density in order to accommodate more swelling, 2) annular fuel geometry to eliminate the need for a sodium bond, 3) minor alloy additions to stabilize lanthanide fission products inside the fuel and prevent their transport to the cladding where they can participate in fuel-cladding chemical interaction (FCCI), and 4) coatings/liners on the cladding inner surface to mitigate FCCI and enable higher temperature operation. This paper will present the current state of development of metallic fuels for actinide transmutation in the US. Highlights will include recent results from metallic fuel casting experiments, experiments to identify alloy additions to immobilize lanthanide fission products, and postirradiation examinations of annular metallic fuels at low burnup.

  5. 78 FR 9281 - Regulation of Fuels and Fuel Additives: 2013 Renewable Fuel Standards (United States)


    ... February 7, 2013 Part V Environmental Protection Agency 40 CFR Part 80 Regulation of Fuels and Fuel Additives: 2013 Renewable Fuel Standards; Proposed Rule #0;#0;Federal Register / Vol. 78 , No. 26 / Thursday... Regulation of Fuels and Fuel Additives: 2013 Renewable Fuel Standards AGENCY: Environmental Protection Agency...

  6. 78 FR 49793 - Regulation of Fuels and Fuel Additives: 2013 Renewable Fuel Standards (United States)


    ... August 15, 2013 Part II Environmental Protection Agency 40 CFR Part 80 Regulation of Fuels and Fuel Additives: 2013 Renewable Fuel Standards; Final Rule #0;#0;Federal Register / Vol. 78, No. 158 / Thursday...-AR43 Regulation of Fuels and Fuel Additives: 2013 Renewable Fuel Standards AGENCY: Environmental...

  7. 75 FR 42237 - Regulation of Fuels and Fuel Additives: 2011 Renewable Fuel Standards (United States)


    ... Protection Agency 40 CFR Part 80 Regulation of Fuels and Fuel Additives: 2011 Renewable Fuel Standards...; ] ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 80 RIN 2060-AQ16 Regulation of Fuels and Fuel Additives: 2011 Renewable Fuel Standards AGENCY: Environmental Protection Agency (EPA). ACTION: Notice of proposed...

  8. Enthalpy and void distributions in subchannels of PHWR fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. W.; Choi, H.; Rhee, B. W. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)


    Two different types of the CANDU fuel bundles have been modeled for the ASSERT-IV code subchannel analysis. From calculated values of mixture enthalpy and void fraction distribution in the fuel bundles, it is found that net buoyancy effect is pronounced in the central region of the DUPIC fuel bundle when compared with the standard CANDU fuel bundle. It is also found that the central region of the DUPIC fuel bundle can be cooled more efficiently than that of the standard fuel bundle. From the calculated mixture enthalpy distribution at the exit of the fuel channel, it is found that the mixture enthalpy and void fraction can be highest in the peripheral region of the DUPIC fuel bundle. On the other hand, the enthalpy and the void fraction were found to be highest in the central region of the standard CANDU fuel bundle at the exit of the fuel channel. This study shows that the subchannel analysis is very useful in assessing thermal behavior of the fuel bundle that could be used in CANDU reactors. 10 refs., 4 figs., 2 tabs. (Author)

  9. Nuclear reactor fuel structure containing uranium alloy wires embedded in a metallic matrix plate (United States)

    Travelli, A.


    A flat or curved plate structure, to be used as fuel in a nuclear reactor, comprises elongated fissionable wires or strips embedded in a metallic continuous non-fissionable matrix plate. The wires or strips are made predominantly of a malleable uranium alloy, such as uranium silicide, uranium gallide or uranium germanide. The matrix plate is made predominantly of aluminum or an aluminum alloy. The wires or strips are located in a single row at the midsurface of the plate, parallel with one another and with the length dimension of the plate. The wires or strips are separated from each other, and from the surface of the plate, by sufficient thicknesses of matrix material, to provide structural integrity and effective fission product retention, under neutron irradiation. This construction makes it safely feasible to provide a high uranium density, so that the uranium enrichment with uranium 235 may be reduced below about 20%, to deter the reprocessing of the uranium for use in nuclear weapons.

  10. EEI/EPRI fuel densification project. Final report. [UO/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Brite, D.W.; Daniel, J.L.; Davis, N.C.; Freshley, M.D.; Hart, P.E.


    A Study is described of in-reactor densification of UO/sub 2/ pellet fuel and the relationship of densification behavior to pellet characteristics and irradiation conditions. Included are a literature survey; fuel material characterization; fuel pellet characterization; pellet, pin, and capsule material fabrication; irradiation; and post-irradiation evaluation. (GRA)

  11. Effectiveness of Prescribed Fire as a Fuel Treatment in Californian Coniferous Forests (United States)

    Nicole M. Vaillant; JoAnn Fites-Kaufman; Scott L. Stephens


    Effective fire suppression for the past century has altered forest structure and increased fuel loads. Prescribed fire as a fuels treatment can reduce wildfire size and severity. This study investigates how prescribed fire affects fuel loads, forest structure, potential fire behavior, and modeled tree mortality at 80th, 90th, and 97.5th percentile fire weather...

  12. Experimental measurements and numerical modeling of marginal burning in live chaparral fuel beds (United States)

    X. Zhou; D.R. Weise; S Mahalingam


    An extensive experimental and numerical study was completed to analyze the marginal burning behavior of live chaparral shrub fuels that grow in the mountains of southern California. Laboratory fire spread experiments were carried out to determine the effects of wind, slope, moisture content, and fuel characteristics on marginal burning in fuel beds of common...

  13. An overview of the fire and fuels extension to the forest vegetation simulator (United States)

    Sarah J. Beukema; Elizabeth D. Reinhardt; Werner A. Kurz; Nicholas L. Crookston


    The Fire and Fuels Extension (FFE) to the Forest Vegetation Simulator (FVS) has been developed to assess the risk, behavior, and impact of fire in forest ecosystems. This extension to the widely-used stand-dynamics model FVS simulates the dynamics of snags and surface fuels as they are affected by stand management (of trees or fuels), live tree growth and mortality,...

  14. ArcFuels User Guide and Tutorial: for use with ArcGIS 9 (United States)

    Nicole M. Vaillant; Alan A. Ager; John Anderson; Lauren. Miller


    Fuel management planning can be a complex problem that is assisted by fire behavior modeling and geospatial analyses. Fuel management often is a particularly complicated process in which the benefits and potential impacts of fuel treatments need to be demonstrated in the context of land management goals and public expectations. Fire intensity, likelihood, and effects...

  15. Characterizing crown fuel distribution for conifers in the interior western United States (United States)

    Seth Ex; Frederick W. Smith; Tara Keyser


    Canopy fire hazard evaluation is essential for prioritizing fuel treatments and for assessing potential risk to firefighters during suppression activities. Fire hazard is usually expressed as predicted potential fire behavior, which is sensitive to the methodology used to quantitatively describe fuel profiles: methodologies that assume that fuel is distributed...

  16. Oxy-fuel combustion of solid fuels

    DEFF Research Database (Denmark)

    Toftegaard, Maja Bøg; Brix, Jacob; Jensen, Peter Arendt


    Oxy-fuel combustion is suggested as one of the possible, promising technologies for capturing CO2 from power plants. The concept of oxy-fuel combustion is removal of nitrogen from the oxidizer to carry out the combustion process in oxygen and, in most concepts, recycled flue gas to lower the flame...... provide additional options for improvement of process economics are however likewise investigated. Of particular interest is the change of the combustion process induced by the exchange of carbon dioxide and water vapor for nitrogen as diluent. This paper reviews the published knowledge on the oxy......-fuel process and focuses particularly on the combustion fundamentals, i.e. flame temperatures and heat transfer, ignition and burnout, emissions, and fly ash characteristics. Knowledge is currently available regarding both an entire oxy-fuel power plant and the combustion fundamentals. However, several...

  17. Household fuels, direct combustion, public perception, fuel

    African Journals Online (AJOL)


    Jul 10, 2005 ... w ere smo k e, fl y - ash and high b urning rate . A ma j or c ause o f the p ro b lems w as the ... Key words: Household fuels, direct combustion, public perception, fuel-switching, food-switching, health impacts. 1 IN TR ..... levels from wood combustion typically exceed the recommended limit by 13 - 50 times ...

  18. Assessment of cold composite fuels for PWR

    Energy Technology Data Exchange (ETDEWEB)

    Coulon-Picard, E.; Agard, M.; Boulore, A.; Castelier, E.; Chabert, C.; Conti, A.; Frayssines, P.E.; Lechelle, J.; Maillard, S.; Matheron, P.; Pelletier, M.; Phelip, M.; Piluso, P.; Vaudano, A


    This study is devoted to evaluation of a new innovative micro structured fuel for future pressurized water reactor. This fuel would have potential to increase the safety margins, lowering fuel temperatures by adding a small fraction of a high conductivity second phase material in the oxide fuel phase. The behavior of this fuel in a standard rod has been modeled with finite element codes and was assessed for different aspects of the cycle as neutronic studies, thermal behavior, reprocessing and economics. Feasibility of fuels has been investigated with the fabrication and characterizations of the microstructure of composite fuels with powder metallurgy and HIP processes. First, a CERCER (Ceramic = UO{sub 2}- Ceramic matrix made of silicon carbide, SiC) fuel type has been investigated, the advantages of a ceramic being generally its transparency to neutrons and its high melting temperature. A first design of kernel type fuel was first chosen with a gap between the UO{sub 2} particles and the second phase material in order to avoid mechanical interaction between the two components. Due to lowering thermal conductivity of SiC under irradiation, this CERCER fuel did not allow a temperature gain compared to current fuel. No ceramic material seems to exhibit all required properties. Even beryllium oxide (BeO), which conductivity does not decrease with irradiation according to the literature, induces difficulties with ({alpha}, n) reactions and toxicity. The study then focused on Cermet fuels (Ceramic-Metal). The metal matrix must be transparent to neutrons and have a good thermal conductivity. Several materials have been considered such as zirconium alloys, austenitic and ferritic stainless steals and chromium based alloys. The heterogeneous composite fuels were modeled using the 3D/CASTM finite element code. From an economical and neutron point of view, it was important to keep a low fraction of metal phase, i.e. less than 10 % of Zr for example. However, the fuel

  19. Fuel related risks; Braenslerisker

    Energy Technology Data Exchange (ETDEWEB)

    Englund, Jessica; Sernhed, Kerstin; Nystroem, Olle; Graveus, Frank (Grontmij AB, (Sweden))


    The project, within which this work report was prepared, aimed to complement the Vaermeforsk publication 'Handbook of fuels' on fuel related risks and measures to reduce the risks. The fuels examined in this project where the fuels included in the first version of the handbook from 2005 plus four additional fuels that will be included in the second and next edition of the handbook. Following fuels were included: woodfuels (sawdust, wood chips, powder, briquettes), slash, recycled wood, salix, bark, hardwood, stumps, straw, reed canary grass, hemp, cereal, cereal waste, olive waste, cocoa beans, citrus waste, shea, sludge, forest industrial sludge, manure, Paper Wood Plastic, tyre, leather waste, cardboard rejects, meat and bone meal, liquid animal and vegetable wastes, tall oil pitch, peat, residues from food industry, biomal (including slaughterhouse waste) and lignin. The report includes two main chapters; a general risk chapter and a chapter of fuel specific risks. The first one deals with the general concept of risk, it highlights laws and rules relevant for risk management and it discuss general risks that are related to the different steps of fuel handling, i.e. unloading, storing, processing the fuel, transportation within the facility, combustion and handling of ashes. The information that was used to produce this chapter was gathered through a literature review, site visits, and the project group's experience from risk management. The other main chapter deals with fuel-specific risks and the measures to reduce the risks for the steps of unloading, storing, processing the fuel, internal transportation, combustion and handling of the ashes. Risks and measures were considered for all the biofuels included in the second version in the handbook of fuels. Information about the risks and risk management was gathered through interviews with people working with different kinds of fuels in electricity and heat plants in Sweden. The information from

  20. Piloted Ignition Regimes of Wildland Fuel Beds (United States)

    Thomas, J. C.; Simeoni, A.; Colella, F.; Torero, J. L.


    Pine needle litters, a key fuel in North American and Mediterranean forest systems, are highly porous fuel beds. They provide a source of continuous fuel medium that can be easily ignited and will sustain flame spread in forest fires. This study is a continuation of previous piloted ignition experimentation [1]. Here, focus was drawn to the influence of airflow in a porous fuel bed for three species: Pinus halepensis, Pinus strobus, and Pinus resinosa. Each needle species is characterized by surface-to-volume ratio and density. The tests samples are characterized by the bulk density, porosity and absorptivity. The needles are subjected to an external radiant heat flux using the FM Global Fire Propagation Apparatus. Ignition delay times and surface temperatures were recorded under a range of different test conditions (basket open area, flow conditions and different level of the radiant heat flux). A comparison of the results indicates that the flow condition must be considered for the modeling of such fuel beds. For conditions where the air flow through the sample is blocked a solid like behavior can be observed. The results show that this cannot be granted for open sample baskets. The goal of this study is to understand the effects, cooling and mixing, of airflow through the porous medium on the time to ignition of the sample and aid in the development of new models for characterizing the ignition behavior.

  1. Advanced fuel system technology for utilizing broadened property aircraft fuels (United States)

    Reck, G. M.


    Factors which will determine the future supply and cost of aviation turbine fuels are discussed. The most significant fuel properties of volatility, fluidity, composition, and thermal stability are discussed along with the boiling ranges of gasoline, naphtha jet fuels, kerosene, and diesel oil. Tests were made to simulate the low temperature of an aircraft fuel tank to determine fuel tank temperatures for a 9100-km flight with and without fuel heating; the effect of N content in oil-shale derived fuels on the Jet Fuel Thermal Oxidation Tester breakpoint temperature was measured. Finally, compatibility of non-metallic gaskets, sealants, and coatings with increased aromatic content jet fuels was examined.

  2. Ternary silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh{sub 4}Si{sub 2-x}Sn{sub x} (RE = Y, Nd, Sm, Gd-Lu) - structure, chemical bonding, and solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vosswinkel, Daniel; Benndorf, Christopher; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics; Matar, Samir F. [Bordeaux Univ., CNRS, ICMCB, UPR 9048, Pessac (France)


    The silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and silicide stannides RERh{sub 4}Si{sub 2-x}Sn{sub x}(RE = Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh{sub 4}Ge{sub 2} type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh{sub 4}Si{sub 2-x}Sn{sub x}. Electronic structure calculations reveal strong covalent Rh-Si bonding as the main stability factor. Multinuclear ({sup 29}Si, {sup 45}Sc, and {sup 89}Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh{sub 4}SiSn and LuRh{sub 4}SiSn.

  3. Timing analysis of PWR fuel pin failures

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.R.; Wade, N.L.; Katsma, K.R.; Siefken, L.J. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Straka, M. (Halliburton NUS, Idaho Falls, ID (United States))


    Research has been conducted to develop and demonstrate a methodology for calculation of the time interval between receipt of the containment isolation signals and the first fuel pin failure for loss-of-coolant accidents (LOCAs). Demonstration calculations were performed for a Babcock and Wilcox (B W) design (Oconee) and a Westinghouse (W) four-loop design (Seabrook). Sensitivity studies were performed to assess the impacts of fuel pin bumup, axial peaking factor, break size, emergency core cooling system availability, and main coolant pump trip on these times. The analysis was performed using the following codes: FRAPCON-2, for the calculation of steady-state fuel behavior; SCDAP/RELAP5/MOD3 and TRACPF1/MOD1, for the calculation of the transient thermal-hydraulic conditions in the reactor system; and FRAP-T6, for the calculation of transient fuel behavior. In addition to the calculation of fuel pin failure timing, this analysis provides a comparison of the predicted results of SCDAP/RELAP5/MOD3 and TRAC-PFL/MOD1 for large-break LOCA analysis. Using SCDAP/RELAP5/MOD3 thermal-hydraulic data, the shortest time intervals calculated between initiation of containment isolation and fuel pin failure are 10.4 seconds and 19.1 seconds for the B W and W plants, respectively. Using data generated by TRAC-PF1/MOD1, the shortest intervals are 10.3 seconds and 29.1 seconds for the B W and W plants, respectively. These intervals are for a double-ended, offset-shear, cold leg break, using the technical specification maximum peaking factor and applied to fuel with maximum design bumup. Using peaking factors commensurate widi actual bumups would result in longer intervals for both reactor designs. This document also contains appendices A through J of this report.

  4. Fuel line purging device

    Energy Technology Data Exchange (ETDEWEB)

    Hensel, R.J.


    In a fuel injection system for an internal combustion engine having a fuel pump communicating with a fuel tank and delivering pressurized fuel through a pressure line to a fuel injector, the improvement is described comprising purging means for purging gas, including air and vapor, from the system, comprising: a housing having an inlet communicating with the pressure line, and having an outlet; pressure responsive valve means in the housing movable between an open position permitting flow from the inlet to the outlet, and a closed position blocking flow from the inlet to the outlet; a first branch passage in the housing communicating between the inlet and one side of the valve means; a second branch passage in the housing communicating between the inlet and the other side of the valve means; restriction means in the second branch passage selected to provide a fuel pressure drop thereacross but not substantially dropping gas pressure thereacross.

  5. Toward sustainable fuel cells

    DEFF Research Database (Denmark)

    Stephens, Ifan; Rossmeisl, Jan; Chorkendorff, Ib


    A quarter of humanity's current energy consumption is used for transportation (1). Low-temperature hydrogen fuel cells offer much promise for replacing this colossal use of fossil fuels with renewables; these fuel cells produce negligible emissions and have a mileage and filling time equal...... to a regular gasoline car. However, current fuel cells require 0.25 g of platinum (Pt) per kilowatt of power (2) as catalysts to drive the electrode reactions. If the entire global annual production of Pt were devoted to fuel cell vehicles, fewer than 10 million vehicles could be produced each year, a mere 10......% of the annual automotive vehicle production. Lowering the Pt loading in a fuel cell to a sustainable level requires the reactivity of Pt to be tuned so that it accelerates oxygen reduction more effectively (3). Two reports in this issue address this challenge (4, 5)....

  6. HTPEM Fuel Cell Impedance

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg

    As part of the process to create a fossil free Denmark by 2050, there is a need for the development of new energy technologies with higher efficiencies than the current technologies. Fuel cells, that can generate electricity at higher efficiencies than conventional combustion engines, can...... potentially play an important role in the energy system of the future. One of the fuel cell technologies, that receives much attention from the Danish scientific community is high temperature proton exchange membrane (HTPEM) fuel cells based on polybenzimidazole (PBI) with phosphoric acid as proton conductor....... This type of fuel cell operates at higher temperature than comparable fuel cell types and they distinguish themselves by high CO tolerance. Platinum based catalysts have their efficiency reduced by CO and the effect is more pronounced at low temperature. This Ph.D. Thesis investigates this type of fuel...

  7. Fuel cell generator with fuel electrodes that control on-cell fuel reformation (United States)

    Ruka, Roswell J [Pittsburgh, PA; Basel, Richard A [Pittsburgh, PA; Zhang, Gong [Murrysville, PA


    A fuel cell for a fuel cell generator including a housing including a gas flow path for receiving a fuel from a fuel source and directing the fuel across the fuel cell. The fuel cell includes an elongate member including opposing first and second ends and defining an interior cathode portion and an exterior anode portion. The interior cathode portion includes an electrode in contact with an oxidant flow path. The exterior anode portion includes an electrode in contact with the fuel in the gas flow path. The anode portion includes a catalyst material for effecting fuel reformation along the fuel cell between the opposing ends. A fuel reformation control layer is applied over the catalyst material for reducing a rate of fuel reformation on the fuel cell. The control layer effects a variable reformation rate along the length of the fuel cell.

  8. Storage of LWR spent fuel in air: Volume 1: Design and operation of a spent fuel oxidation test facility

    Energy Technology Data Exchange (ETDEWEB)

    Thornhill, C.K.; Campbell, T.K.; Thornhill, R.E.


    This report describes the design and operation and technical accomplishments of a spent-fuel oxidation test facility at the Pacific Northwest Laboratory. The objective of the experiments conducted in this facility was to develop a data base for determining spent-fuel dry storage temperature limits by characterizing the oxidation behavior of light-water reactor (LWR) spent fuels in air. These data are needed to support licensing of dry storage in air as an alternative to spent-fuel storage in water pools. They are to be used to develop and validate predictive models of spent-fuel behavior during dry air storage in an Independent Spent Fuel Storage Installation (ISFSI). The present licensed alternative to pool storage of spent fuel is dry storage in an inert gas environment, which is called inerted dry storage (IDS). Licensed air storage, however, would not require monitoring for maintenance of an inert-gas environment (which IDS requires) but does require the development of allowable temperature limits below which UO/sub 2/ oxidation in breached fuel rods would not become a problem. Scoping tests at PNL with nonirradiated UO/sub 2/ pellets and spent-fuel fragment specimens identified the need for a statistically designed test matrix with test temperatures bounding anticipated maximum acceptable air-storage temperatures. This facility was designed and operated to satisfy that need. 7 refs.

  9. Synergistic Smart Fuel For Microstructure Mediated Measurements

    Energy Technology Data Exchange (ETDEWEB)

    James A. Smith; Dale K. Kotter; Steven L. Garrett; Randall A. Ali


    Advancing the Nuclear Fuel Cycle and Next Generation Nuclear Power Plants requires enhancing our basic understanding of fuel and materials behavior under irradiation. The two most significant issues limiting the effectiveness and lifespan of the fuel are the loss of thermal conductivity of the fuel and the mechanical strength of both fuel and cladding. The core of a nuclear reactor presents an extremely harsh and challenging environment for both sensors and telemetry due to elevated temperatures and large fluxes of energetic and ionizing particles from radioactive decay processes. The majority of measurements are made in reactors using “radiation hardened” sensors and materials. A different approach has been pursued in this research that exploits high temperatures and materials that are robust with respect to ionizing radiation. This synergistically designed thermoacoustic sensor will be self-powered, wireless, and provide telemetry. The novel sensor will be able to provide reactor process information even if external electrical power and communication are unavailable. In addition, the form-factor for the sensor is identical to the existing fuel rods within reactors and contains no moving parts. Results from initial proof of concept experiments designed to characterize porosity, surface properties and monitor gas composition will be discussed.

  10. Synergistic smart fuel for microstructure mediated measurements

    Energy Technology Data Exchange (ETDEWEB)

    Smith, James A.; Kotter, Dale K. [Idaho National Laboratory, Fuel Performance and Design, P.O. Box 1625, Idaho Falls, Idaho, 83415-6188 (United States); Ali, Randall A. [Graduate Program in Acoustics and Applied Research Laboratory, Penn State University, P. . Box 30, M/S 3520D, State College, PA 16804-0030 (United States); Garrett, Steven L. [Graduate Program in Acoustics and Applied Research Laboratory, Penn State University, P.O. Box 30, M/S 3520D, State College, PA 16804-0030 (United States)


    Advancing the Nuclear Fuel Cycle and Next Generation Nuclear Power Plants requires enhancing our basic understanding of fuel and materials behavior under irradiation. The two most significant issues limiting the effectiveness and lifespan of the fuel are the loss of thermal conductivity of the fuel and the mechanical strength of both fuel and cladding. The core of a nuclear reactor presents an extremely harsh and challenging environment for both sensors and telemetry due to elevated temperatures and large fluxes of energetic and ionizing particles from radioactive decay processes. The majority of measurements are made in reactors using 'radiation hardened' sensors and materials. A different approach has been pursued in this research that exploits high temperatures and materials that are robust with respect to ionizing radiation. This synergistically designed thermoacoustic sensor will be self-powered, wireless, and provide telemetry. The novel sensor will be able to provide reactor process information even if external electrical power and communication are unavailable. In addition, the form-factor for the sensor is identical to the existing fuel rods within reactors and contains no moving parts. Results from initial proof of concept experiments designed to characterize porosity, surface properties and monitor gas composition will be discussed.

  11. Development of breached pin performance analysis code SAFFRON (System of Analyzing Failed Fuel under Reactor Operation by Numerical method)

    Energy Technology Data Exchange (ETDEWEB)

    Ukai, Shigeharu [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center


    On the assumption of fuel pin failure, the breached pin performance analysis code SAFFRON was developed to evaluate the fuel pin behavior in relation to the delayed neutron signal response during operational mode beyond the cladding failure. Following characteristic behavior in breached fuel pin is modeled in 3-dimensional finite element method : pellet swelling by fuel-sodium reaction, fuel temperature change, and resultant cladding breach extension and delayed neutron precursors release into coolant. Particularly, practical algorithm of numerical procedure in finite element method was originally developed in order to solve the 3-dimensional non-linear contact problem between the swollen pellet due to fuel-sodium reaction and breached cladding. (author).

  12. Liquid fuel cells

    Directory of Open Access Journals (Sweden)

    Grigorii L. Soloveichik


    Full Text Available The advantages of liquid fuel cells (LFCs over conventional hydrogen–oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented.

  13. Liquid fuel cells (United States)


    Summary The advantages of liquid fuel cells (LFCs) over conventional hydrogen–oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented. PMID:25247123

  14. Liquid fuel cells. (United States)

    Soloveichik, Grigorii L


    The advantages of liquid fuel cells (LFCs) over conventional hydrogen-oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented.

  15. High Temperature Fuel Cladding Chemical Interactions Between TRIGA Fuels and 304 Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Emmanuel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Keiser, Jr., Dennis D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Forsmann, Bryan [Boise State Univ., ID (United States); Janney, Dawn E. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Henley, Jody [Idaho National Lab. (INL), Idaho Falls, ID (United States); Woolstenhulme, Eric C. [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    High-temperature fuel-cladding chemical interactions (FCCI) between TRIGA (Training, Research, Isotopes, General Atomics) fuel elements and the 304 stainless steel (304SS) are of interest to develop an understanding of the fuel behavior during transient reactor scenarios. TRIGA fuels are composed of uranium (U) particles dispersed in a zirconium-hydride (Zr-H) matrix. In reactor, the fuel is encased in 304-stainless-steel (304SS) or Incoloy 800 clad tubes. At high temperatures, the fuel can readily interact with the cladding, resulting in FCCI. A number of FCCI can take place in this system. Interactions can be expected between the cladding and the Zr-H matrix, and/or between the cladding and the U-particles. Other interactions may be expected between the Zr-H matrix and the U-particles. Furthermore, the fuel contains erbium-oxide (Er-O) additions. Interactions can also be expected between the Er-O, the cladding, the Zr-H and the U-particles. The overall result is that very complex interactions may take place as a result of fuel and cladding exposures to high temperatures. This report discusses the characterization of the baseline fuel microstructure in the as-received state (prior to exposure to high temperature), characterization of the fuel after annealing at 950C for 24 hours and the results from diffusion couple experiments carries out at 1000C for 5 and 24 hours. Characterization was carried out via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with sample preparation via focused ion beam in situ-liftout-technique.

  16. Primary Reference Fuels (PRFs) as Surrogates for Low Sensitivity Gasoline Fuels

    KAUST Repository

    Bhavani Shankar, Vijai Shankar


    Primary Reference Fuels (PRFs) - binary mixtures of n-heptane and iso-octane based on Research Octane Number (RON) - are popular gasoline surrogates for modeling combustion in spark ignition engines. The use of these two component surrogates to represent real gasoline fuels for simulations of HCCI/PCCI engines needs further consideration, as the mode of combustion is very different in these engines (i.e. the combustion process is mainly controlled by the reactivity of the fuel). This study presents an experimental evaluation of PRF surrogates for four real gasoline fuels termed FACE (Fuels for Advanced Combustion Engines) A, C, I, and J in a motored CFR (Cooperative Fuels Research) engine. This approach enables the surrogate mixtures to be evaluated purely from a chemical kinetic perspective. The gasoline fuels considered in this study have very low sensitivities, S (RON-MON), and also exhibit two-stage ignition behavior. The first stage heat release, which is termed Low Temperature Heat Release (LTHR), controls the combustion phasing in this operating mode. As a result, the performance of the PRF surrogates was evaluated by its ability to mimic the low temperature chemical reactivity of the real gasoline fuels. This was achieved by comparing the LTHR from the engine pressure histories. The PRF surrogates were able to consistently reproduce the amount of LTHR, closely match the phasing of LTHR, and the compression ratio for the start of hot ignition of the real gasoline fuels. This suggests that the octane quality of a surrogate fuel is a good indicator of the fuel’s reactivity across low (LTC), negative temperature coefficient (NTC), and high temperature chemical (HTC) reactivity regimes.


    Energy Technology Data Exchange (ETDEWEB)



    In May 2004 alpha contamination was found on the lid of the pre-filter housing in the Sodium Removal Ion Exchange System during routine filter change. Subsequent investigation determined that the alpha contamination likely came from a fuel pin(s) contained in an Ident-69 (ID-69) type pin storage container serial number 9 (ID-69-9) that was washed in the Sodium Removal System (SRS) in January 2004. Because all evidence indicated that the wash water interacted with the fuel, this ID49 is designated as containing a failed fuel pin with gross cladding defect and was set aside in the Interim Examination and Maintenance (IEM) Cell until it could be determined how to proceed for long term dry storage of the fuel pin container. This ID49 contained fuel pins from the driver fuel assembly (DFA) 16392, which was identified as a Delayed Neutron Monitor (DNM) leaker assembly. However, this DFA was disassembled and the fuel pin that was thought to be the failed pin was encapsulated and was not located in this ID49 container. This failed fuel disposition study discusses two alternatives that could be used to address long term storage for the contents of ID-69-9. The first alternative evaluated utilizes the current method of identifying and storing DNM leaker fuel pin(s) in tubes and thus, verifying that the alpha contamination found in the SRS came from a failed pin in this pin container. This approach will require unloading selected fuel pins from the ID-69, visually examining and possibly weighing suspect fuel pins to identify the failed pin(s), inserting the failed pin(s) in storage tubes, and reloading the fuel pins into ID49 containers. Safety analysis must be performed to revise the 200 Area Interim Storage Area (ISA) Final Safety Analysis Report (FSAR) (Reference 1) for this fuel configuration. The second alternative considered is to store the failed fuel as-is in the ID-69. This was evaluated to determine if this approach would comply with storage requirements. This

  18. Nuclear fuel pin scanner (United States)

    Bramblett, Richard L.; Preskitt, Charles A.


    Systems and methods for inspection of nuclear fuel pins to determine fiss loading and uniformity. The system includes infeed mechanisms which stockpile, identify and install nuclear fuel pins into an irradiator. The irradiator provides extended activation times using an approximately cylindrical arrangement of numerous fuel pins. The fuel pins can be arranged in a magazine which is rotated about a longitudinal axis of rotation. A source of activating radiation is positioned equidistant from the fuel pins along the longitudinal axis of rotation. The source of activating radiation is preferably oscillated along the axis to uniformly activate the fuel pins. A detector is provided downstream of the irradiator. The detector uses a plurality of detector elements arranged in an axial array. Each detector element inspects a segment of the fuel pin. The activated fuel pin being inspected in the detector is oscillated repeatedly over a distance equal to the spacing between adjacent detector elements, thereby multiplying the effective time available for detecting radiation emissions from the activated fuel pin.

  19. Fuel cell catalyst degradation

    DEFF Research Database (Denmark)

    Arenz, Matthias; Zana, Alessandro


    Fuel cells are an important piece in our quest for a sustainable energy supply. Although there are several different types of fuel cells, the by far most popular is the proton exchange membrane fuel cell (PEMFC). Among its many favorable properties are a short start up time and a high power density...... increasing focus. Activity of the catalyst is important, but stability is essential. In the presented perspective paper, we review recent efforts to investigate fuel cell catalysts ex-situ in electrochemical half-cell measurements. Due to the amount of different studies, this review has no intention to give...

  20. Computational Design of Advanced Nuclear Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Savrasov, Sergey [Univ. of California, Davis, CA (United States); Kotliar, Gabriel [Rutgers Univ., Piscataway, NJ (United States); Haule, Kristjan [Rutgers Univ., Piscataway, NJ (United States)


    The objective of the project was to develop a method for theoretical understanding of nuclear fuel materials whose physical and thermophysical properties can be predicted from first principles using a novel dynamical mean field method for electronic structure calculations. We concentrated our study on uranium, plutonium, their oxides, nitrides, carbides, as well as some rare earth materials whose 4f eletrons provide a simplified framework for understanding complex behavior of the f electrons. We addressed the issues connected to the electronic structure, lattice instabilities, phonon and magnon dynamics as well as thermal conductivity. This allowed us to evaluate characteristics of advanced nuclear fuel systems using computer based simulations and avoid costly experiments.

  1. Pattern recognition monitoring of PEM fuel cell (United States)

    Meltser, Mark Alexander


    The CO-concentration in the H.sub.2 feed stream to a PEM fuel cell stack is monitored by measuring current and voltage behavior patterns from an auxiliary cell attached to the end of the stack. The auxiliary cell is connected to the same oxygen and hydrogen feed manifolds that supply the stack, and discharges through a constant load. Pattern recognition software compares the current and voltage patterns from the auxiliary cell to current and voltage signature determined from a reference cell similar to the auxiliary cell and operated under controlled conditions over a wide range of CO-concentrations in the H.sub.2 fuel stream.

  2. Forest fuels and predicted fire behavior in the first 5 years after a bark beetle outbreak with and without timber harvest (Project INT-EM-F-11-04) [Chapter 12 (United States)

    Carolyn Sieg; Kurt Allen; Chad Hoffman; Joel McMillin


    Unprecedented levels of tree mortality from native bark beetle species have occurred in a variety of forest types in Western United States and Canada in recent decades in response to beetle-favorable forest and climatic conditions (Bentz 2009, Meddens and others 2012). Previous studies suggest that bark beetle outbreaks alter stand structural attributes and fuel...

  3. Thermodynamic analysis of SOFC (solid oxide fuel cell) - Stirling hybrid plants using alternative fuels

    DEFF Research Database (Denmark)

    Rokni, Masoud


    . Simulations of the proposed system were conducted using different fuels, which should facilitate the use of a variety of fuels depending on availability. Here, the results for natural gas (NG), ammonia, di-methyl ether (DME), methanol and ethanol are presented and analyzed. The system behavior is further......A novel hybrid power system (∼10 kW) for an average family home is proposed. The system investigated contains a solid oxide fuel cell (SOFC) on top of a Stirling engine. The off-gases produced in the SOFC cycle are fed to a bottoming Stirling engine, at which additional power is generated...... investigated by comparing the effects of key factors, such as the utilization factor and the operating conditions under which these fuels are used. Moreover, the effect of using a methanator on the plant efficiency is also studied. The combined system improves the overall electrical efficiency relative...

  4. Self-sustaining fuel purging fuel injection system

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, J.R.; Koblish, T.R.


    A fuel injector system for a combustor of a gas turbine engine includes first and second fuel injectors rendered operative to discharge fuel to the combustor during a high power regime of engine operation and rendered non-operative during a lower power regime of engine operation. The first and second fuel injectors include respective first and second fuel discharge passages in fuel flow communication to one another and to the combustor via associated fuel discharge lips to sustain a flame region. The first and second fuel injectors are operatively associated with respective first and second air discharge means having air discharge lips for discharging air to the combustor for sustaining the flame region therein. When the fuel injectors are rendered non-operative, different pneumatic pressures are established at the fuel discharge lips to purge fuel from the fuel injectors to the combustor. 26 figs.

  5. Advanced fuel system technology for utilizing broadened property aircraft fuels (United States)

    Reck, G. M.


    Possible changes in fuel properties are identified based on current trends and projections. The effect of those changes with respect to the aircraft fuel system are examined and some technological approaches to utilizing those fuels are described.

  6. Fuel tank integrity research : fuel tank analyses and test plans (United States)


    The Federal Railroad Administrations Office of Research : and Development is conducting research into fuel tank : crashworthiness. Fuel tank research is being performed to : determine strategies for increasing the fuel tank impact : resistance to ...

  7. On the effects of fuel properties and injection timing in partially premixed compression ignition of low octane fuels

    KAUST Repository

    Naser, Nimal


    A better understanding on the effects of fuel properties and injection timing is required to improve the performance of advanced engines based on low temperature combustion concepts. In this work, an experimental and computational study was conducted to investigate the effects of physical and chemical kinetic properties of low octane fuels and their surrogates in partially premixed compression ignition (PPCI) engines. The main objective was to identify the relative importance of physical versus chemical kinetic properties in predicting practical fuel combustion behavior across a range of injection timings. Two fuel/surrogate pairs were chosen for comparison: light naphtha (LN) versus the primary reference fuel (PRF) with research octane number of 65 (PRF 65), and FACE (fuels for advanced combustion engines) I gasoline versus PRF 70. Two sets of parametric studies were conducted: the first varied the amount of injected fuel mass at different injection timings to match a fixed combustion phasing, and the second maintained the same injected fuel mass at each injection timing to assess resulting combustion phasing changes. Full-cycle computational fluid dynamic engine simulations were conducted by accounting for differences in the physical properties of the original and surrogate fuels, while employing identical chemical kinetics. The simulations were found to capture trends observed in the experiments, while providing details on spatial mixing and chemical reactivity for different fuels and injection timings. It was found that differences in physical properties become increasingly important as injection timing was progressively delayed from premixed conditions, and this was rationalized by analysis of mixture stratification patterns resulting from injection of fuels with different physical properties. The results suggest that accurate descriptions of both physical and chemical behavior of fuels are critical in predictive simulations of PPCI engines for a wide range of

  8. Remote fabrication and irradiation test of recycled nuclear fuel prepared by the oxidation and reduction of spent oxide fuel (United States)

    Jin Ryu, Ho; Chan Song, Kee; Il Park, Geun; Won Lee, Jung; Seung Yang, Myung


    A direct dry recycling process was developed in order to reuse spent pressurized light water reactor (LWR) nuclear fuel in CANDU reactors without the separation of sensitive nuclear materials such as plutonium. The benefits of the dry recycling process are the saving of uranium resources and the reduction of spent fuel accumulation as well as a higher proliferation resistance. In the process of direct dry recycling, fuel pellets separated from spent LWR fuel rods are oxidized from UO2 to U3O8 at 500 °C in an air atmosphere and reduced into UO2 at 700 °C in a hydrogen atmosphere, which is called OREOX (oxidation and reduction of oxide fuel). The pellets are pulverized during the oxidation and reduction processes due to the phase transformation between cubic UO2 and orthorhombic U3O8. Using the oxide powder prepared from the OREOX process, the compaction and sintering processes are performed in a remote manner in a shielded hot cell due to the high radioactivity of the spent fuel. Most of the fission gas and volatile fission products are removed during the OREOX and sintering processes. The mini-elements fabricated by the direct dry recycling process are irradiated in the HANARO research reactor for the performance evaluation of the recycled fuel pellets. Post-irradiation examination of the irradiated fuel showed that microstructural evolution and fission gas release behavior of the dry-recycled fuel were similar to high burnup UO2 fuel.

  9. Analysis of UO{sub 2}-BeO fuel under transient using fuel performance code

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Daniel S.; Abe, Alfredo Y.; Muniz, Rafael O.R.; Giovedi, Claudia, E-mail:, E-mail:, E-mail:, E-mail: [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Universidade de São Paulo (USP), São Paulo, SP (Brazil). Departamento de Engenharia Naval e Oceânica


    Recent research has appointed the need to replace the classic fuel concept, used in light water reactors. Uranium dioxide has a weak point due to the low thermal conductivity, that produce high temperatures on the fuel. The ceramic composite fuel formed of uranium dioxide (UO{sub 2}), with the addition of beryllium oxide (BeO), presents high thermal conductivity compared with UO{sub 2}. The oxidation of zirconium generates hydrogen gas that can create a detonation condition. One of the preferred options are the ferritic alloys formed of iron-chromium and aluminum (FeCrAl), that should avoid the hydrogen release due to oxidation. In general, the FeCrAl alloys containing 10 - 20Cr, 3 - 5Al, and 0 - 0.12Y in weight percent. The FeCrAl alloys should exhibit a slow oxidation kinetics due to chemical composition. Resistance to oxidation in the presence of steam is improved as a function of the content of chromium and aluminum. In this way, the thermal and mechanical properties of the UO{sub 2}-BeO-10%vol, composite fuel were coupled with FeCrAl alloys and added to the fuel codes. In this work, we examine the fuel rod behavior of UO{sub 2}-10%vol-BeO/FeCrAl, including a simulated transient of reactivity. The fuels behavior shown reduced temperature with UO{sub 2}-BeO/Zr, UO{sub 2}-BeO/FeCrAl also were compared with UO{sub 2}/Zr system. The case reactivity initiated accident analyzed, reproducing the fuel rod called VA-1 using UO{sub 2}/Zr alloys and compared with UO{sub 2}-BeO/FeCrAl. (author)

  10. Fuel Supply Defaults for Regional Fuels and Fuel Wizard Tool in MOVES201X (United States)

    The fuel supply report documents the data and methodology used to derive the default gasoline, diesel and fuel-blend fuel properties, and their respective fuel market share in MOVES. The default market share of the individual fuels varies by calendar year, seasons, and several do...

  11. 78 FR 14190 - Regulation of Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel... (United States)


    ... AGENCY 40 CFR Part 80 RIN 2060-AR07 Regulation of Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel Pathways Under the Renewable Fuel Standard Program AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA is issuing a final rule identifying additional fuel...

  12. Framing car fuel efficiency : linearity heuristic for fuel consumption and fuel-efficiency ratings

    NARCIS (Netherlands)

    Schouten, T.M.; Bolderdijk, J.W.; Steg, L.


    People are sensitive to the way information on fuel efficiency is conveyed. When the fuel efficiency of cars is framed in terms of fuel per distance (FPD; e.g. l/100 km), instead of distance per units of fuel (DPF; e.g. km/l), people have a more accurate perception of potential fuel savings. People

  13. 77 FR 13009 - Regulation of Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel... (United States)


    ... AGENCY 40 CFR Part 80 RIN 2060-AR07 Regulation of Fuels and Fuel Additives: Identification of Additional Qualifying Renewable Fuel Pathways Under the Renewable Fuel Standard Program AGENCY: Environmental Protection... January 5, 2012 to amend the Renewable Fuel Standard program regulations. Because EPA received adverse...

  14. Solar fuel generator (United States)

    Lewis, Nathan S.; West, William C.


    The disclosure provides conductive membranes for water splitting and solar fuel generation. The membranes comprise an embedded semiconductive/photoactive material and an oxygen or hydrogen evolution catalyst. Also provided are chassis and cassettes containing the membranes for use in fuel generation.

  15. Solar Fuel Generator (United States)

    Lewis, Nathan S. (Inventor); West, William C. (Inventor)


    The disclosure provides conductive membranes for water splitting and solar fuel generation. The membranes comprise an embedded semiconductive/photoactive material and an oxygen or hydrogen evolution catalyst. Also provided are chassis and cassettes containing the membranes for use in fuel generation.

  16. Nanofluidic fuel cell (United States)

    Lee, Jin Wook; Kjeang, Erik


    Fuel cells are gaining momentum as a critical component in the renewable energy mix for stationary, transportation, and portable power applications. State-of-the-art fuel cell technology benefits greatly from nanotechnology applied to nanostructured membranes, catalysts, and electrodes. However, the potential of utilizing nanofluidics for fuel cells has not yet been explored, despite the significant opportunity of harnessing rapid nanoscale reactant transport in close proximity to the reactive sites. In the present article, a nanofluidic fuel cell that utilizes fluid flow through nanoporous media is conceptualized and demonstrated for the first time. This transformative concept captures the advantages of recently developed membraneless and catalyst-free fuel cell architectures paired with the enhanced interfacial contact area enabled by nanofluidics. When compared to previously reported microfluidic fuel cells, the prototype nanofluidic fuel cell demonstrates increased surface area, reduced activation overpotential, superior kinetic characteristics, and moderately enhanced fuel cell performance in the high cell voltage regime with up to 14% higher power density. However, the expected mass transport benefits in the high current density regime were constrained by high ohmic cell resistance, which could likely be resolved through future optimization studies.

  17. Are Solar Fuels Sustainable?

    NARCIS (Netherlands)

    Meuwese, Anne


    Summary The combined problems of too little fossil fuels to supply the world’s future energy needs and the possible negative environmental effects of carbon dioxide emissions which are coupled to their usage has led to the development of fuels based on s

  18. Fuel cell electronics packaging

    National Research Council Canada - National Science Library

    Kuang, Ken; Easler, Keith


    ... more energy independent. Despite the fact that the primary focus of the new initiative revolved around automotive technologies, the President's Hydrogen Fuel Initiative was crafted into a balanced program that benefited a wide range of technologies and applications, including micro, portable, stationary fuel cells. This massive effort was given an addition...

  19. Durable fuel electrode

    DEFF Research Database (Denmark)


    the composite. The invention also relates to the use of the composite as a fuel electrode, solid oxide fuel cell, and/or solid oxide electrolyser. The invention discloses a composite for an electrode, comprising a three-dimensional network of dispersed metal particles, stabilised zirconia particles and pores...

  20. Alternative fuel for automobiles

    Energy Technology Data Exchange (ETDEWEB)

    Editor [Korea Energy Management Corporation, Songnam (Korea)


    Recently the developed countries are showing great interest on use of an alternative energy as a fuel for a transport. Korea decided to import 5,000 CNG bus by 2002 and operate in six megalopolis including Seoul. The possibility and problems of using a clean alternative fuel for automobile are discussed.