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Sample records for sintered spherical pellets

  1. Fabrication of Sintered Annular Fuel Pellet

    International Nuclear Information System (INIS)

    Rhee, Young Woo; Kim, Dong Joo; Kim, Jong Hun; Yang, Jae Ho; Kim, Keon Sik; Kang, Ki Won; Song, Kun Woo

    2010-01-01

    A dual cooled annular fuel has been seriously considered as a favorable option for uprating the power density of a Pressurized Water Reactor fuel assembly. An annular fuel has a geometrically inherent advantage such as an increased heat transfer area and a thin pellet thickness. It results in a lot of advantages from the point of a fuel safety and its economy. In order to actualize the dual cooled fuel, an essential element is the annular pellet with precisely controlled diametric tolerance. However, the unique shape of annular fuel pellet causes challenging difficulties to satisfy a diametric tolerance specification. Because of an inhomogeneous green density distribution along the compact height, an hour-glassing usually occurred in a sintered cylindrical PWR fuel pellet fabricated by a conventional doubleacting press. Thus, a sintered pellet usually undergoes a centerless grinding process in order to secure a pellet's specifications. In the case of an annular pellet fabrication using a conventional double-acting press, the same hour-glass shape would probably occur. The outer diameter tolerance of an annular pellet can be controlled easily similar to that of a conventional cylindrical PWR pellet through a centerless grinding. However, it appears not to be simple in the case of an inner surface grinding. It would be the best way to satisfy the specifications for the inner diameter in an as-fabricated pellet. In the present study, we are trying to find a way to minimize the diametric tolerance of the sintered annular pellet without inner surface grinding. This paper deals with a new approach that we have tried to reduce the diametric tolerance of the sintered annular pellet

  2. Sintering of dioxide pellets in an oxidizing atmosphere (CO2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.

    1992-01-01

    This work consists in the study of the sintering process of U O 2 pellets in an oxidizing atmosphere. Sintering tests were performed in an CO 2 atmosphere and the influence of temperature and time on the pellets density and microstructure were verified. The results obtained were compared to those from the conventional sintering process and its efficiency was confirmed. (author)

  3. Pellet-press-to-sintering-boat nuclear fuel pellet loading system

    International Nuclear Information System (INIS)

    Bucher, G.D.

    1988-01-01

    This patent describes a system for loading nuclear fuel pellets into a sintering boat from a pellet press which ejects newly made the pellets from a pellet press die table surface. The system consists of: (a) a bowl having an inner surface, a longitudinal axis, an open and generally circular top of larger diameter, and an open and generally circular bottom of smaller diameter; (b) means for supporting the bowl in a generally upright position such that the bowl is rotatable about its longitudinal axis; (c) means for receiving the ejected pellets proximate the die table surface of the pellet press and for discharging the received pellets into the bowl at a location proximate the inner surface towards the top of the bowl with a pellet velocity having a horizontal component which is generally tangent to the inner surface of the bowl proximate the location; (d) means for rotating the bowl about the longitudinal axis such that the bowl proximate the location has a velocity generally equal, in magnitude and direction, to the horizontal component of the pellet velocity at the location; and (e) means for moving the sintering boat generally horizontally beneath and proximate the bottom of the bowl

  4. Approximate ballistics formulas for spherical pellets in free flight

    Directory of Open Access Journals (Sweden)

    E.J. Allen

    2018-02-01

    Full Text Available The ballistics equations for spherical pellets in free flight are simplified through appropriate scaling of the pellet velocity and pellet distance. Two different drag coefficient curves are averaged to yield a single curve applicable to shot pellets and round balls. The resulting S-shaped drag coefficient curve is approximated by three straight-line segments. The scaled ballistics equations are then solved exactly and simple formulas are found for the velocity and flight time with respect to trajectory distance. The formulas are applicable to spherical shot pellets and round balls of any composition under any atmospheric conditions. The formulas are amenable to quick and easy computation and may also serve as an aid in understanding and comparing black-box ballistics calculators. For shotshell ballistics, an important assumption in the present investigation is that the pellets are moving as single, free spheres and not as a dense cloud or in a shot column, in particular, the pellets are not interacting during flight. Therefore, the formulas are most appropriate for single round balls, for large shot sizes, and for pellets of small shot size fired from open chokes. The formulas are clear and accessible, and can be implemented by military or law enforcement personnel as well as hunters and shooters. This work differs from previous investigations in that accurate ballistics formulas are derived for spherical projectiles of shotguns and muzzleloaders using realistic drag coefficients.

  5. Standard specification for sintered (Uranium-Plutonium) dioxide pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This specification covers finished sintered and ground (uranium-plutonium) dioxide pellets for use in thermal reactors. It applies to uranium-plutonium dioxide pellets containing plutonium additions up to 15 % weight. This specification may not completely cover the requirements for pellets fabricated from weapons-derived plutonium. 1.2 This specification does not include (1) provisions for preventing criticality accidents or (2) requirements for health and safety. Observance of this specification does not relieve the user of the obligation to be aware of and conform to all applicable international, federal, state, and local regulations pertaining to possessing, processing, shipping, or using source or special nuclear material. Examples of U.S. government documents are Code of Federal Regulations Title 10, Part 50Domestic Licensing of Production and Utilization Facilities; Code of Federal Regulations Title 10, Part 71Packaging and Transportation of Radioactive Material; and Code of Federal Regulations Tit...

  6. Sintering of uranium dioxide pellets (UO2) in an oxidizing atmosphere (C O2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.

    1992-01-01

    This work consists in the study of the sintering process of U O 2 pellets in an oxidizing atmosphere. Sintering tests were performed in an CO 2 atmosphere and the influence of temperature and time on the pellets density and microstructure were verified. The results obtained were compared to those from the conventional sintering process and its efficiency was confirmed. (author)

  7. Standard specification for sintered gadolinium oxide-uranium dioxide pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification is for finished sintered gadolinium oxide-uranium dioxide pellets for use in light-water reactors. It applies to gadolinium oxide-uranium dioxide pellets containing uranium of any 235U concentration and any concentration of gadolinium oxide. 1.2 This specification recognizes the presence of reprocessed uranium in the fuel cycle and consequently defines isotopic limits for gadolinium oxide-uranium dioxide pellets made from commercial grade UO2. Such commercial grade UO2 is defined so that, regarding fuel design and manufacture, the product is essentially equivalent to that made from unirradiated uranium. UO2 falling outside these limits cannot necessarily be regarded as equivalent and may thus need special provisions at the fuel fabrication plant or in the fuel design. 1.3 This specification does not include (1) provisions for preventing criticality accidents or (2) requirements for health and safety. Observance of this specification does not relieve the user of the obligation to be aw...

  8. Furnace for the continuous sintering of pellets of ceramic nuclear fuel material

    International Nuclear Information System (INIS)

    Heyraud, J.

    1977-01-01

    The furnace comprises a hearth for the longitudinal displacement of pellet containers, means for injecting gas at both ends of the furnace, for sucking gas between preheating and sintering zones and for condensing the binder, means for displacing the containers from an introduction lock-chamber to an extraction lock-chamber, a conveyor belt which passes through a glove box and provides a leak-tight connection between the lock-chambers. A station for loading containers with pellet sub-containers prior to sintering and a station for unloading the pellet sub-containers after sintering are juxtaposed within the glove box. 3 claims, 1 drawing figure

  9. The Effect of the O/U Ratio on the Sintered Density of the UO2 Pellet

    International Nuclear Information System (INIS)

    Na, S. H.; Kang, K. H.; Kim, Y. H.; Park, C. J.; Song, K. C.; Yoo, M. J.

    2008-01-01

    The sintered density of the UO 2 pellet is an important factor to assure a stable nuclear reactor control. There are some methods to control the sintered density of the UO 2 pellet, that is, a sintering temperature and its time, a green density, an addition of pore-former or U 3 O 8 , etc. In general, it is well known that the sintered density of UO 2 pellet increases as the sintering temperature and its time and the green density increases. However the addition of a pore-former or U 3 O 8 decreases the sintered density of the UO 2 pellet, due to the leave various sizes of pore in the UO 2 matrix during sintering. In this work, the effect of the O/U ratio on the sintered density of the UO 2 pellet are investigated

  10. The sintering of dioxide pellets (UO2) in an oxidizing atmosphere (CO2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.; Riella, H.G.

    1993-06-01

    In this study the process of sintering of U O 2 pellets in oxidative atmosphere has been evaluated. Temperature and time of study have been varied in order to determine the influence of these parameters on final density and microstructure of the material. The NIKUSI process, allows to work in a temperature range below to those that have been employed in the conventional process, lowering in up to 50% the sintering cycle because it is possible to decrease the time of sintering. (author)

  11. Pressing-sintering process of UO2 pellet of controllable microstructure

    International Nuclear Information System (INIS)

    Wu Zhiming; Peng Qingshan

    1999-11-01

    The authors present the pressability and sinterability of two different matrix UO 2 powders from Ammonium Diuranate (ADU) process and the improvements by adding different quantities of additives. A focal point is made in the effect of the additives on the density, thermal stability and microstructure of UO 2 pellet. It is indicated by the results that a UO 2 pellet being of proper density, good thermal stability and better microstructure can be produced using of high sinterable UO 2 powder ex ADU, adding a certain quantity of pore former through calculation under conditions of high green density and high sintering temperature

  12. Effect of recycling blast furnace flue dust as pellets on the sintering performance

    Directory of Open Access Journals (Sweden)

    El-Hussiny N.A.

    2010-01-01

    Full Text Available The Egyptian Iron and Steel Company generates a great amount of blast furnace flue dust. The recovery of metals and carbon from this flue dust becomes a very important demand due to the increase of the price of coke breeze and the decrease of the primary source of metals. At the same time, it make the environment more safe by decreasing pollution. Introducing these dust fines in the sintering process proves to be very harmful for different operating parameters. Thus, this study aims at investigating the production of pellets resulting from these fines, using molasses as organic binder and its application in sintering of iron ore. The sintering experiments were performed using flue dust as pellets as a substitute of coke breeze. The results revealed that, sintering properties such as inter strength increases with using the flue dust pellets, while productivity of both the sinter machine and sinter machine at blast furnace yard decreases. Also the vertical velocity of the sinter machine and the weight loss during the reduction of produced the sinter by hydrogen decrease.

  13. Zirconium carbonitride pellets by internal sol gel and spark plasma sintering as inert matrix fuel material

    Science.gov (United States)

    Hedberg, Marcus; Cologna, Marco; Cambriani, Andrea; Somers, Joseph; Ekberg, Christian

    2016-10-01

    Inert matrix fuel is a fuel type where the fissile material is blended with a solid diluent material. In this work zirconium carbonitride microspheres have been produced by internal sol gel technique, followed by carbothermal reduction. Material nitride purities in the produced materials ranged from Zr(N0.45C0.55) to Zr(N0.74C0.26) as determined by X-ray diffraction and application of Vegard's law. The zirconium carbonitride microspheres have been pelletized by spark plasma sintering (SPS) and by conventional cold pressing and sintering. In all SPS experiments cohesive pellets were formed. Maximum final density reached by SPS at 1700 °C was 87% theoretical density (TD) compared to 53% TD in conventional sintering at 1700 °C. Pore sizes in all the produced pellets were in the μm scale and no density gradients could be observed by computer tomography.

  14. Reduced gaseous emissions from Corus strip products Ijmuiden sinter and pellet plants

    Energy Technology Data Exchange (ETDEWEB)

    Leuwerink, T.; van der Panne, A. [Corus Iron Manufacturing IJmuiden, IJmuiden (Netherlands). Raw Materials and Agglomeration

    2001-07-01

    At Corus Strip Products IJmuiden (formerly Hoogovens Steel), the Netherlands, about 4.4 and 4.6 million tons of sinter and pellets respectively are produced per year. In the two blast furnaces, the sinter and pellets are converted to about 5.7 million tons of hot metal. The high temperature treatment which the iron ore is subjected to in the sinter and pellet plants gives rise to the formation of noxious compounds like SO{sub 2}, NOx, dust and dioxins. Like other integrated steel works, Corus Strip Products Ijmuiden is faced with stricter environmental regulations with respect to gaseous and aqueous emissions. This spurred the building of a flue gas recirculation system, a wet scrubber process and water treatment systems for these plants. This paper gives an overview of the results accomplished to date and outlines further emission reductions in the future. 8 refs., 6 figs., 2 tabs.

  15. Studies on sintering kinetics of ThO2-UO2 pellets using master sintering curve approach

    Science.gov (United States)

    Banerjee, Joydipta; Ray, Aditi; Kumar, Arun; Banerjee, Srikumar

    2013-11-01

    Three different compositions of thoria-urania pellets, namely, ThO2-4%UO2, ThO2-10%UO2 and ThO2-20%UO2 (all compositions are in wt% containing natural uranium) were fabricated by Coated Agglomerate Pelletization (CAP) process. The compositions studied in the current paper are the proposed fuels for the forthcoming Indian Advanced Heavy water Reactor (AHWR) and its variant based on low enriched uranium. Sintering kinetics of ThO2-x%UO2 (x = 4, 10, 20) green pellets, thus fabricated, were evaluated using constant heating rate experiments in a vertical dilatometer. Activation energies of sintering (Q) were estimated using Arrhenius plot as proposed by Wang and Raj. Master Sintering Curves (MSC) for the above three compositions were constructed using shrinkage data. A FORTRAN program, employing optimization based numerical algorithm for fitting relative density vs. work of sintering data with sigmoid function, was used for this purpose. The apparent activation energies, evaluated using MSC principle, appear to be consistent with the values obtained by Arrhenius plot.

  16. Nuclear energy - Determination of chlorine and fluorine in uranium dioxide powder and sintered pellets

    International Nuclear Information System (INIS)

    2008-01-01

    This International Standard describes a method for determining the chlorine and fluorine concentrations in uranium dioxide and in sintered fuel pellets by pyrohydrolysis of samples, followed either by liquid ion-exchange chromatography or by selective electrode measurement of chlorine and fluorine ions. Many ion-exchange chromatography systems and ion-selective electrode measurement systems are available

  17. Optimization of hot melt extrusion parameters for sphericity and hardness of polymeric face-cut pellets

    Science.gov (United States)

    Alshetaili, Abdullah S.; Almutairy, Bjad K.; Alshahrani, Saad M.; Ashour, Eman A.; Tiwari, Roshan V.; Alshehri, Sultan M.; Feng, Xin; Alsulays, Bader B.; Majumdar, Soumyajit; Langley, Nigel; Kolter, Karl; Gryczke, Andreas; Martin, Scott T.; Repka, Michael A.

    2016-01-01

    The aim of this study was to formulate face-cut, melt extruded pellets and to optimize hot melt process parameters to obtain maximized sphericity and hardness by utilizing Soluplus® as a polymeric carrier and carbamazepine (CBZ) as a model drug. Thermal gravimetric analysis (TGA) was used to detect thermal stability of CBZ. The Box-Behnken design for response surface methodology was developed using three factors, processing temperature (°C), feeding rate (%), and screw speed (rpm), which resulted in 17 experimental runs. The influence of these factors on pellet sphericity and mechanical characteristics was assessed and evaluated for each experimental run. Pellets with optimal sphericity and mechanical properties were chosen for further characterization. This included differential scanning calorimetry, drug release, hardness friability index (HFI), flowability, bulk density, tapped density, Carr’s index, and fourier transform infrared radiation (FTIR) spectroscopy. TGA data showed no drug degradation upon heating to 190°C. Hot melt extrusion (HME) processing conditions were found to have a significant effect on the pellet shape and hardness profile. Pellets with maximum sphericity and hardness exhibited no crystalline peak after extrusion. The rate of drug release was affected mainly by pellet size, where smaller pellets released the drug faster. All optimized formulations were found to be of superior hardness and not friable. The flow properties of optimized pellets were excellent with high bulk and tapped density. PMID:27080252

  18. Standard test methods for analysis of sintered gadolinium oxide-uranium dioxide pellets

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 These test methods cover procedures for the analysis of sintered gadolinium oxide-uranium dioxide pellets to determine compliance with specifications. 1.2 The analytical procedures appear in the following order: Section Carbon (Total) by Direct CombustionThermal Conductivity Method C1408 Test Method for Carbon (Total) in Uranium Oxide Powders and Pellets By Direct Combustion-Infrared Detection Method Chlorine and Fluorine by Pyrohydrolysis Ion-Selective Electrode Method C1502 Test Method for Determination of Total Chlorine and Fluorine in Uranium Dioxide and Gadolinium Oxide Gadolinia Content by Energy-Dispersive X-Ray Spectrometry C1456 Test Method for Determination of Uranium or Gadolinium, or Both, in Gadolinium Oxide-Uranium Oxide Pellets or by X-Ray Fluorescence (XRF) Hydrogen by Inert Gas Fusion C1457 Test Method for Determination of Total Hydrogen Content of Uranium Oxide Powders and Pellets by Carrier Gas Extraction Isotopic Uranium Composition by Multiple-Filament Surface-Ioni...

  19. Synthesis of dense yttrium-stabilised hafnia pellets for nuclear applications by spark plasma sintering

    International Nuclear Information System (INIS)

    Tyrpekl, Vaclav; Holzhäuser, Michael; Hein, Herwin; Vigier, Jean-Francois; Somers, Joseph; Svora, Petr

    2014-01-01

    Graphical abstract: Densification of HfO 2 –Y 2 O 3 micro-beads by Spark Plasma Sintering High density pellets with homogenous distribution of Hf and Y serve as neutron absorbers. - Abstract: Dense yttrium–stabilised hafnia pellets (91.35 wt.% HfO 2 and 8.65 wt.% Y 2 O 3 ) were prepared by spark plasma sintering consolidation of micro-beads synthesised by the “external gelation” sol–gel technique. This technique allows a preparation of HfO 2 –Y 2 O 3 beads with homogenous yttria–hafnia solid solution. A sintering time of 5 min at 1600 °C was sufficient to produce high density pellets (over 90% of the theoretical density) with significant reproducibility. The pellets have been machined in a lathe to the correct dimensions for use as neutron absorbers in an experimental test irradiation in the High Flux Reactor (HFR) in Petten, Holland, in order to investigate the safety of americium based nuclear fuels

  20. Sintering of Spherical Particles of Equal and Different Size Arranged in a Body Centered Cubic Structure

    DEFF Research Database (Denmark)

    Redanz, Pia; McMeeking, R. M.

    2003-01-01

    Solid-state sintering of a bcc structure of spherical particles has been studied numerically by use of simple shape parameters to describe the state of the unit cell. Both free and pressure-assisted sintering of particles of equal and different sizes for various ratios of boundary and surface dif...

  1. Water cooling system for sintering furnaces of nuclear fuel pellets

    International Nuclear Information System (INIS)

    1996-01-01

    This work has as a main objective to develop a continuous cooling water system, which is necessary for the cooling of the sintering furnaces. This system is used to protect them as well as for reducing the water consumption, ejecting the heat generated into this furnaces and scattering it into the atmosphere in a fast and continuous way. The problem was defined and the reference parameters established, making the adequate research. The materials were selected as well as the length of the pipeline which will carry the secondary refrigerant fluid (water). Three possible solutions were tried,and evaluated, and from these, the thermal and economically most efficient option was selected. The layout of the solution was established and the theoretical construction of a cooling system for liquids using dichlorofluoromethane (R-22), as a refrigerant and a air cooled condenser, was accomplished. (Author)

  2. UO2 fuel pellets fabrication via Spark Plasma Sintering using non-standard molybdenum die

    Science.gov (United States)

    Papynov, E. K.; Shichalin, O. O.; Mironenko, A. Yu; Tananaev, I. G.; Avramenko, V. A.; Sergienko, V. I.

    2018-02-01

    The article investigates spark plasma sintering (SPS) of commercial uranium dioxide (UO2) powder of ceramic origin into highly dense fuel pellets using non-standard die instead of usual graphite die. An alternative and formerly unknown method has been suggested to fabricate UO2 fuel pellets by SPS for excluding of typical problems related to undesirable carbon diffusion. Influence of SPS parameters on chemical composition and quality of UO2 pellets has been studied. Also main advantages and drawbacks have been revealed for SPS consolidation of UO2 in non-standard molybdenum die. The method is very promising due to high quality of the final product (density 97.5-98.4% from theoretical, absence of carbon traces, mean grain size below 3 μm) and mild sintering conditions (temperature 1100 ºC, pressure 141.5 MPa, sintering time 25 min). The results are interesting for development and probable application of SPS in large-scale production of nuclear ceramic fuel.

  3. Determination of Sintered (Th,U)O2 Pellet at the Grain Growth Step

    International Nuclear Information System (INIS)

    Indrati-Y, Tundjung; Pristi-Hartati, Murdani; Ari-Handayani; Ginting, Aslina Br

    2000-01-01

    The determination of sintered (Th,U)O 2 pellet at the grain growth stephave been done by dilatometer and Scanning Electron Microscope (SEM). Thecalculation method based on the densification curve and quantitativemetallurgy. The green pellet be produced by single action compaction. Itspellet was heated on the dilatometer with heating rate 11 o C/minute and inthe argon atmosphere, 2 liters/hour. The activation energy at thedensification step can be calculated by densification curve only, but theactivation energy at the grain growth step can be calculated by densificationcurve or quantitative metallurgy. The capability of the dilatometer can beoperated until 1200 o C, so the densification curve based on the experiencecan be used to calculate activation energy at the densification step, 4.492kcal/mole. The activation energy at the grain growth step, which is 25.277kcal/mole, can be predicted by trial and error on n value. That activationenergy is almost the same with activation energy that based on thequantitative metallurgy method 25.042 kcal/mole. All of the activation energyfor the (Th,U)O 2 pellet sintering process is 29.769 kcal/mole. (author)

  4. Spark plasma sintering and microstructural analysis of pure and Mo doped U3Si2 pellets

    Science.gov (United States)

    Lopes, Denise Adorno; Benarosch, Anna; Middleburgh, Simon; Johnson, Kyle D.

    2017-12-01

    U3Si2 has been considered as an alternative fuel for Light Water Reactors (LWRs) within the Accident Tolerant Fuels (ATF) initiative, begun after the Fukushima-Daiichi Nuclear accidents. Its main advantages are high thermal conductivity and high heavy metal density. Despite these benefits, U3Si2 presents an anisotropic crystallographic structure and low solubility of fission products, which can result in undesirable effects under irradiation conditions. In this paper, spark plasma sintering (SPS) of U3Si2 pellets is studied, with evaluation of the resulting microstructure. Additionally, exploiting the short sintering time in SPS, a molybdenum doped pellet was produced to investigate the early stages of the Mo-U3Si2 interaction, and analyze how this fission product is accommodated in the fuel matrix. The results show that pellets of U3Si2 with high density (>95% TD) can be obtained with SPS in the temperature range of 1200°C-1300 °C. Moreover, the short time employed in this technique was found to generate a unique microstructure for this fuel, composed mainly of closed nano-pores (uranium with small quantities of dissolved Si and Mo at the front of the reaction.

  5. Investigation of the sintering mechanisms for (U,Am)O{sub 2} pellets obtained by CRMP process

    Energy Technology Data Exchange (ETDEWEB)

    Caisso, M. [CEA, Centre de Marcoule, DEN, DTEC/SECA/LFC, F-30207 Bagnols-sur-Ceze (France); CEA, Centre de Marcole, DEN, DRCP/SERA/LCAR, F-30207 Bagnols-sur-Ceze (France); Institut Europeen des Membranes, UMR 5635 CNRS-ENSCM-UM, CC047, Campus Triolet, Universite de Montpellier, F-34095 Montpellier Cedex 5 (France); Boulesteix, R.; Maitre, A. [SPCTS, UMR 7315 CNRS-Universite de Limoges-ENSCI, Centre Europeen de la Ceramique, 12 Rue Atlantis, F-87068 Limoges (France); Picart, S.; Delahaye, T. [CEA, Centre de Marcole, DEN, DRCP/SERA/LCAR, F-30207 Bagnols-sur-Ceze Cedex (France); Ayral, A. [Institut Europeen des Membranes, UMR 5635 CNRS-ENSCM-UM, CC047, Campus Triolet Universite de Montpellier, F-34095 Montpellier Cedex 5 (France)

    2016-07-01

    The use of CRMP (Calcined Resin Microsphere Pelletization) process for AmBB (Americium Bearing Blankets) fabrication is today a key research axis in americium transmutation domain, where its very high activity requires minimization of powder dissemination. In this aim, the use of oxide microspheres as compaction precursors is a promising clean alternative to powder metallurgy. Understanding the different steps of densification during CRMP pellet sintering thus appears as fundamental to obtain final materials with the specific features required for AmBB. The densification curve recorded in dynamic conditions shows different sintering steps. A first decrease of shrinkage rate happens at low temperature, around 1100 K. This phenomenon is not normally observed in the sintering of conventional powders. Chemical and microstructural studies were performed on (U,Am)O{sub 2} and also on (Ce,Gd)O{sub 2} surrogate compound to highlight the causes of this low-temperature sintering step. Multi-scale reorganization finally appears as the sole explanation, through the sintering of nano-metric aggregate present in the green pellet and related to the morphology of the starting microspheres employed as pelletization precursors. (authors)

  6. Release characteristics of cesium from green pellet fabricated with spent fuel under different sintering conditions

    International Nuclear Information System (INIS)

    Park, Geun Il; Lee, Dou Youn; Lee, Young Soon; Kim, Woong Ki; Lee, Jae Won; Lee, Jung Won; Yang, Myung Seung

    2005-01-01

    The dry process, known as DUPIC(Direct Use of spent PWR fuel in CANDU reactor), for fabricating fuel pellets from spent fuel as recycling technology has been well demonstrated by establishing an optimization process for fuel fabrication through a number of batch processes using typical PWR spent fuel. As considering a strategy for extending the burn-up in LWR fuel, experimental verification for analyzing the effect of spent fuel burn-up on fuel fabrication is necessary in some respects that one of key parameters influencing the fuel fabrication characteristic would amount of fission products contained as impurity elements in spent fuel. A high burn-up spent fuel has a higher amount of fission products compared with typical spent fuel irradiated in about 27,000 MWd/tU. A preliminary study showed that the sintered pellet density fabricated with a high burn-up fuel has a lower value than that of common fuel burn-ups of about 30,000 MWd/tU. To provide better understanding a remote fuel fabrication characteristic in an aspect of wide ranges of spent fuel generated from PWR reactor, the influence of fission products release on fabrication characteristics of the dry processed fuel with a high burn-up fuel of 65,000 MWd/tU were experimentally evaluated. It is expected that key fission product affecting fabrication characteristics in dry process is cesium isotope due to the boiling point of 670 .deg. C and the low dissociation temperature of its oxides(<700 .deg. C). This study focus to analyze the release characteristics of cesium from green pellets fabricated with a variation of compaction pressure under different sintering conditions using tubular furnace in IMEF M6 hot cell

  7. Studies on sintering kinetics of ThO{sub 2}–UO{sub 2} pellets using master sintering curve approach

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Joydipta, E-mail: joydipta@barc.gov.in [Radiometallurgy Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ray, Aditi [Theoretical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kumar, Arun [Nuclear Fuels Group, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Banerjee, Srikumar [Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2013-11-15

    Three different compositions of thoria–urania pellets, namely, ThO{sub 2}–4%UO{sub 2}, ThO{sub 2}–10%UO{sub 2} and ThO{sub 2}–20%UO{sub 2} (all compositions are in wt% containing natural uranium) were fabricated by Coated Agglomerate Pelletization (CAP) process. The compositions studied in the current paper are the proposed fuels for the forthcoming Indian Advanced Heavy water Reactor (AHWR) and its variant based on low enriched uranium. Sintering kinetics of ThO{sub 2}–x%UO{sub 2} (x = 4, 10, 20) green pellets, thus fabricated, were evaluated using constant heating rate experiments in a vertical dilatometer. Activation energies of sintering (Q) were estimated using Arrhenius plot as proposed by Wang and Raj. Master Sintering Curves (MSC) for the above three compositions were constructed using shrinkage data. A FORTRAN program, employing optimization based numerical algorithm for fitting relative density vs. work of sintering data with sigmoid function, was used for this purpose. The apparent activation energies, evaluated using MSC principle, appear to be consistent with the values obtained by Arrhenius plot.

  8. Effect of additives in sintering UO2-7wt%Gd2O3 fuel pellets

    International Nuclear Information System (INIS)

    Santos, L.R.; Riella, H.G.

    2009-01-01

    Gadolinium has been used as burnable poison for reactivity control in modern PWRs. The incorporation of Gd 2 O 3 powder directly into the UO 2 powder enables longer fuel cycles and optimized fuel utilization. Nevertheless, processing by this method leads to difficulties while obtaining sintered pellets with the minimum required density. The process for manufacturing UO 2 - Gd 2 O 3 generates scraps that should be reused. The main scraps are green and sintered pellets, which must be calcined to U 3 O 8 to return to the fabrication process. Also, the incorporation of Gd 2 O 3 in UO 2 requires the use of an additive to improve the sintering process, in order to achieve the physical properties specified for the mixed fuel, mainly density and microstructure. This paper describes the effect of the addition of fabrication scraps on the properties of the UO 2 -Gd 2 O 3 fuel. Aluminum hydroxide Al(OH) 3 was also incorporated to the fuel as a sintering aid. The results shown that the use of 2000 ppm of Al(OH) 3 as additive allow to fabricate good pellets with up to 10 wt% of recycled scraps. (author)

  9. Homogeneity characterisation of (U,Gd)O2 sintered pellets by X-ray diffraction powder analysis applying Rietveld method

    International Nuclear Information System (INIS)

    Leyva, Ana G.; Vega, Daniel R.; Trimarco, Veronica G.; Marchi, Daniel E.

    1999-01-01

    The (U,Gd)O 2 sintered pellets are fabricated by different methods. The homogeneity characterisation of Gd content seems to be necessary as a production control to qualify the process and the final product. The micrographic technique is the most common method used to analyse the homogeneity of these samples, this method requires time and expertise to obtain good results. In this paper, we propose an analysis of the X-ray diffraction powder patterns through the Rietveld method, in which the differences between the experimental data and the calculated from a crystalline structure model proposed are evaluated. This result allows to determine the cell parameters, that can be correlated with the Gd concentration, and the existence of other phases with different Gd ratio. (author)

  10. Repetitive Solid Spherical Pellet Injection and Irradiation toward the Repetitive-mode Fast-Ignition Fusion miniReactor CANDY.

    Science.gov (United States)

    HANAYAMA, Ryohei; KOMEDA, Osamu; NISHIMURA, Yasuhiko; MORI, Yoshitaka; ISHII, Katsuhiro; NAKAYAMA, Suisei; OKIHARA, Shinichiro; FUJITA, Kazuhisa; SEKINE, Takashi; SATO, Nakahiro; KURITA, Takashi; KAWASHIMA, Toshiyuki; KAN, Hirofumi; NAKAMURA, Naoki; KONDO, Takuya; FUJINE, Manabu; AZUMA, Hirozumi; HIOKI, Tatsumi; KAKENO, Mitsutaka; MOTOHIRO, Tomoyoshi; SUNAHARA, Atsushi; SENTOKU, Yasuhiko; MIURA, Eisuke; KITAGAWA, Yoneyoshi

    2016-03-01

    Pellet injection and repetitive laser illumination are key technologies for realizing inertial fusion energy[1-4]. Neutron generator using lasers also requires a repeating pellet target supplier. Here we present the first demonstration of target injection and neutron generation[5]. We injected more than 1300 spherical deuterated polystyrene(C8D8) bead pellet targets during 23 minutes at 1 Hz(Fig. 1). After the pellet targets fell for a distance of 18 cm, we applied the synchronized laser-diode-pumped ultra-intense laser HAMA. The laser intensity at the focal point is 5 x 1018 W/cm2, which is high enough to generate neutrons. As a result of the irradiation, we produced 2.45-MeV DD neutrons. Figure 2 shows the neutron time-of-flight signals detected by plastic scintillators coupled to photomultipliers. The neutron energy was calculated by the time-of-flight method. The maximum neutron yield was 9.5 x 104/4π sr. The result is a step toward fusion power and also suggests possible industrial neutron sources.

  11. Repetitive Solid Spherical Pellet Injection and Irradiation toward the Repetitive-mode Fast-Ignition Fusion miniReactor CANDY

    International Nuclear Information System (INIS)

    HANAYAMA, Ryohei; KOMEDA, Osamu; NISHIMURA, Yasuhiko; MORI, Yoshitaka; ISHII, Katsuhiro; NAKAYAMA, Suisei; OKIHARA, Shinichiro; FUJITA, Kazuhisa; SEKINE, Takashi; SATO, Nakahiro; KAWASHIMA, Toshiyuki; KAN, Hirofumi; KURITA, Takashi; NAKAMURA, Naoki; KONDO, Takuya; FUJINE, Manabu; AZUMA, Hirozumi; HIOKI, Tatsumi; KAKENO, Mitsutaka; MOTOHIRO, Tomoyoshi

    2016-01-01

    Pellet injection and repetitive laser illumination are key technologies for realizing inertial fusion energy [1-4]. Neutron generator using lasers also requires a repeating pellet target supplier. Here we present the first demonstration of target injection and neutron generation[5]. We injected more than 1300 spherical deuterated polystyrene(C 8 D 8 ) bead pellet targets during 23 minutes at 1 Hz(Fig. 1). After the pellet targets fell for a distance of 18 cm, we applied the synchronized laser-diode-pumped ultra-intense laser HAMA. The laser intensity at the focal point is 5 x 10 18 W/cm 2 , which is high enough to generate neutrons. As a result of the irradiation, we produced 2.45-MeV DD neutrons. Figure 2 shows the neutron time-of-flight signals detected by plastic scintillators coupled to photomultipliers. The neutron energy was calculated by the time-of-flight method. The maximum neutron yield was 9.5 x 10 4 /4π sr. The result is a step toward fusion power and also suggests possible industrial neutron sources. (paper)

  12. A study on the sinterability enhancement of dry recycling nuclear fuel pellets by using simulated spent fuel

    International Nuclear Information System (INIS)

    Kim, Woong Ki; Lee, Jae Won; Shin, Won Chul; Lee, Jung Won

    2004-01-01

    Burnup of nuclear fuel was continuously increased to enhance economy of nuclear power plants. In 1960's, burnup ranged 20,000∼30,000 MWd/tU. In 1990's, it reached 60,000 MWd/tU. A lot of high burnup spent PWR fuel will be discharged in the future. In this study, to study fabrication characteristics of dry recycling nuclear fuel from spent PWR fuel with high burnup of 60,000 MWd/tU, the fission products of spent PWR fuel was analyzed by ORIGEN-2 code. Simulated spent PWR fuel pellets were fabricated by using UO 2 powder added by the simulated fission products. The simulated dry-recycling-fuel pellets were fabricated by dry recycling fuel fabrication flow including 3 cycle treated OREOX(Oxidation and Reduction of Oxide fuel) process. A small amount of dopant such as TiO 2 , Nb 2 O 5 , Li 2 O are added to enhance sinterability of the powder

  13. Compatibility of ferritic steels with sintered Li2O pellets in a flowing-helium environment

    International Nuclear Information System (INIS)

    Chopra, O.K.; Kurasawa, T.; Smith, D.L.

    1983-01-01

    The compatibility of ferritic HT-9 alloy and Fe-9Cr-1Mo steel with Li 2 O pellets has been investigated at 823 K (550 0 C) in flowing helium containing 93 or 1 ppM H 2 O and 1 ppM H 2 . The results indicate that the alloy specimens gain weight whereas the Li 2 O pellets lose weight after exposure. There is a net loss in weight of the total reaction couple. Both steels develop an iron-rich outer scale and chromium-rich subscale. The reaction rates in helium containing 93 ppM H 2 O are greater than in helium containing 1 ppM H 2 O. The depth of internal penetration for specimens exposed in helium with 1 ppM H 2 O reaches a constant value after approx. 3.6 Ms. The specimens exposed in helium containing 93 ppM H 2 O show a gradual increase in penetration up to 7.2 Ms. For both moisture contents, the total scale thickness follows a power law and the reaction rates decrease with time. The weight losses for Li 2 O pellets follow a linear law and yield values of 12.2 and 3.8%/year in helium with 93 and 1 ppM H 2 O, respectively

  14. Disposition of excess plutonium using ''off-spec'' MOX pellets as a sintered ceramic waste form

    International Nuclear Information System (INIS)

    Armantrout, G.A.; Jardine, L.J.

    1996-02-01

    The authors describe a potential strategy for the disposition of excess weapons plutonium in a way that minimizes (1) technological risks, (2) implementation costs and completion schedules, and (3) requirements for constructing and operating new or duplicative Pu disposition facilities. This is accomplished by an optimized combination of (1) using existing nuclear power reactors to ''burn'' relatively pure excess Pu inventories as mixed oxide (MOX) fuel and (2) using the same MOX fuel fabrication facilities to fabricate contaminated or impure excess Pu inventories into an ''off-spec'' MOX solid ceramic waste form for geologic disposition. Diversion protection for the SCWF to meet the ''spent fuel standard'' introduced by the National Academy of Sciences can be achieved in at least three ways. (1) One can utilize the radiation field from defense high-level nuclear waste by first packaging the SCWF pellets in 2- to 4-L cans that are subsequently encapsulated in radioactive glass in the Defense Waste Processing Facility (DWPF) glass canisters (a ''can-in-canister'' approach). (2) One can add 137 Cs (recovered from defense wastes at Hanford and currently stored as CsCl in capsules) to an encapsulating matrix such as cement for the SCWF pellets in a small hot-cell facility and thus fabricate large monolithic forms. (3) The SCWF can be fabricated into reactor fuel-like pellets and placed in tubes similar to fuel assemblies, which can then be mixed in sealed repository containers with irradiated spent nuclear fuel for geologic disposition

  15. Nuclear energy - Uranium dioxide powder and sintered pellets - Determination of oxygen/uranium atomic ratio by the amperometric method. 2. ed.

    International Nuclear Information System (INIS)

    2007-01-01

    This International Standard specifies an analytical method for the determination of the oxygen/uranium atomic ratio in uranium dioxide powder and sintered pellets. The method is applicable to reactor grade samples of hyper-stoichiometric uranium dioxide powder and pellets. The presence of reducing agents or residual organic additives invalidates the procedure. The test sample is dissolved in orthophosphoric acid, which does not oxidize the uranium(IV) from UO 2 molecules. Thus, the uranium(VI) that is present in the dissolved solution is from UO 3 and/or U 3 O 8 molecules only, and is proportional to the excess oxygen in these molecules. The uranium(VI) content of the solution is determined by titration with a previously standardized solution of ammonium iron(II) sulfate hexahydrate in orthophosphoric acid. The end-point of the titration is determined amperometrically using a pair of polarized platinum electrodes. The oxygen/uranium ratio is calculated from the uranium(VI) content. A portion, weighing about 1 g, of the test sample is dissolved in orthophosphoric acid. The dissolution is performed in an atmosphere of nitrogen or carbon dioxide when sintered material is being analysed. When highly sintered material is being analysed, the dissolution is performed at a higher temperature in purified phosphoric acid from which the water has been partly removed. The cooled solution is titrated with an orthophosphoric acid solution of ammonium iron(II) sulfate, which has previously been standardized against potassium dichromate. The end-point of the titration is detected by the sudden increase of current between a pair of polarized platinum electrodes on the addition of an excess of ammonium iron(II) sulfate solution. The paper provides information about scope, principle, reactions, reagents, apparatus, preparation of test sample, procedure (uranium dioxide powder, sintered pellets of uranium dioxide, highly sintered pellets of uranium dioxide and determination

  16. Sintering of nonstoichiometric UO2

    International Nuclear Information System (INIS)

    Susnik, D.; Holc, J.

    1983-01-01

    Activated sintering of UO 2 pellets at 1100 deg C is described. In CO 2 atmosphere is UO 2 is nonstoichiometric and pellets from active UO 2 powders sinter at 900 deg C to high density. At 1100 deg C the final sintered density is practically achieved at heating on sintering temperature. After reduction and cooling in H 2 atmosphere which is followed sintering in CO 2 the structure is identical to the structured UO 2 pellets sintered at high temperature in H 2 . Density of activated sintered UO 2 pellets is stable, even after additional sintering at 1800 deg C. (author)

  17. Reduced gaseous emissions from Corus Strip products Ljmuiden sinter and pellet plants; Reduction des emissions gazeuses a l'usine de production d'agglomeres et de boulettes de Corus Strip Products a Ljmuiden

    Energy Technology Data Exchange (ETDEWEB)

    Leuwerink, T.; Van Der Panne, A. [Corus Iron Manufacturing Ljmuiden Raw Materials and Agglomeration, Ljmuiden (Netherlands)

    2001-07-01

    At Corus Strip Products Ljmuiden (formerly Hoogovens Steel), the Netherlands, ca. 4.4 and 4.6 million tons of sinter and pellets respectively, are produced per year. In the two blast furnaces, the sinter and pellets are converted to ca. 5.7 million tons of hot metal. The high temperature treatment which the iron ore is subjected to in the sinter and pellet plants gives rise to the formation of noxious compounds like SO{sub 2}, NO{sub x}, dust and dioxins. Like other integrated steel works, Corus Strip Products Ljmuiden is faced with stricter environmental regulations with respect to gaseous and aqueous emissions. This spurred the building of a flue gas recirculation system (Emission Optimized Sintering), a wet scrubber process (Airfine) and water treatment systems for these plants. This paper gives an overview of the results accomplished to date and outlines further emission reductions in the future. (authors)

  18. Effect of Al(OH)3 on the sintering of UO2-Gd2O3 fuel pellets with addition of U3O8 from recycle

    Science.gov (United States)

    dos Santos, Lauro Roberto; Durazzo, Michelangelo; Urano de Carvalho, Elita Fontenele; Riella, Humberto Gracher

    2017-09-01

    The incorporation of gadolinium as burnable poison directly into nuclear fuel is important for reactivity compensation, which enables longer fuel cycles. The function of the burnable poison fuel is to control the neutron population in the reactor core during its startup and the beginning of the fuel burning cycle to extend the use of the fuel. The implementation of UO2-Gd2O3 poisoned fuel in Brazil has been proposed according to the future requirements established for the Angra-2 nuclear power plant. The UO2 powder used is produced from the Ammonium Uranyl Carbonate (AUC). The incorporation of Gd2O3 powder directly into the AUC-derived UO2 powder by dry mechanical blending is the most attractive process, because of its simplicity. Nevertheless, processing by this method leads to difficulties while obtaining sintered pellets with the minimum required density. The cause of the low densities is the bad sintering behavior of the UO2-Gd2O3 mixed fuel, which shows a blockage in the sintering process that hinders the densification. This effect has been overcome by microdoping of the fuel with small quantities of aluminum. The process for manufacturing the fuel inevitably generates uranium-rich scraps from various sources. This residue is reincorporated into the production process in the form of U3O8 powder additions. The addition of U3O8 also hinders densification in sintering. This study was carried out to investigate the influence of both aluminum and U3O8 additives on the density of fuel pellets after sintering. As the effects of these additives are counterposed, this work studied the combined effect thereof, seeking to find an applicable composition for the production process. The experimental results demonstrated the effectiveness of aluminum, in the form of Al(OH)3, as an additive to promote increase in the densification of the (U,Gd)O2 pellets during sintering, even with high additions of U3O8 recycled from the manufacturing process.

  19. Quantification of the effect of in-situ generated uranium metal on the experimentally determined O/U ratio of a sintered uranium dioxide fuel pellet

    International Nuclear Information System (INIS)

    Narasimha Murty, B.; Bharati Misra, U.; Yadav, R.B.; Srivastava, R.K.

    2005-01-01

    This paper describes quantitatively the effect of in-situ generated uranium metal (that could be formed due to the conducive manufacturing conditions) in a sintered uranium dioxide fuel pellet on the experimentally determined O/U ratio using analytical methods involving dissolution of the pellet material. To quantify the effect of in-situ generated uranium metal in the fuel pellet, a mathematical expression is derived for the actual O/U ratio in terms of the O/U ratio as determined by an experiment involving dissolution of the material and the quantity of uranium metal present in the uranium dioxide pellet. The utility of this derived mathematical expression is demonstrated by tabulating the calculated actual O/U ratios for varying amounts of uranium metal (from 5 to 95% in 5% intervals) and different O/U ratio values (from 2.001 to 2.015 in 0.001 intervals). This paper brings out the necessity of care to be exercised while interpreting the experimentally determined O/U ratio and emphasizes the fact that it is always safer to produce the nuclear fuel with oxygen to uranium ratios well below the specified maximum limit of 2.015. (author)

  20. Influence of binders on infrared laser ablation of powdered tungsten carbide pressed pellets in comparison with sintered tungsten carbide hardmetals studied by inductively coupled plasma atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hola, Marketa [Research Centre for Environmental Chemistry and Ecotoxicology and Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic); Otruba, Vitezslav [Research Centre for Environmental Chemistry and Ecotoxicology and Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic); Kanicky, Viktor [Research Centre for Environmental Chemistry and Ecotoxicology and Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic)]. E-mail: viktork@chemi.muni.cz

    2006-05-15

    Laser ablation (LA) was studied as a sample introduction technique for the analysis of powdered and sintered tungsten carbides (WC/Co) by inductively coupled plasma optical emission spectrometry (ICP-OES). The possibility to work with powdered and compact materials with close chemical composition provided the opportunity to compare LA sampling of similar substances in different forms that require different preparation procedures. Powdered WC/Co precursors of sintered hardmetals were prepared for the ablation as pressed pellets with and without powdered silver as a binder, while sintered hardmetal blocks were embedded into a resin to obtain discs, which were then smoothed and polished. A Q-switched Nd:YAG laser operated at its fundamental wavelength of 1064 nm with a pulse frequency of 10 Hz and maximum pulse energy of 220 mJ was used. A single lens was used for the laser beam focusing. An ablation cell (14 cm{sup 3}) mounted on a PC-controlled XY-translator was connected to an ICP spectrometer Jobin Yvon 170 Ultrace (laterally viewed ICP, mono- and polychromator) using a 1.5-m tubing (4 mm i.d.). Ablation was performed in a circular motion (2 mm diameter). Close attention was paid to the study of the crater parametres depending on hardness, cohesion and Ag binder presence in WC/Co samples. The influence of the Co content on the depth and structure of the ablation craters of the binderless pellets was also studied. Linear calibration plots of Nb, Ta and Ti were obtained for cemented WC/Co samples, binderless and binder-containing pellets. Relative widths of uncertainty intervals about the centroids vary between {+-} 3% and {+-} 7%, and exceptionally reach a value above 10%. The lowest determinable quantities (LDQ) of Nb, Ta and Ti calculated from the calibration lines were less than 0.5% (m/m). To evaluate the possibility of quantitative elemental analysis by LA-ICP-OES, two real sintered WC/Co samples and two real samples of powdered WC/Co materials were analysed

  1. Uranium dioxide pellets

    International Nuclear Information System (INIS)

    Zawidzki, T.W.

    1979-01-01

    Sintered uranium dioxide pellets composed of particles of size > 50 microns suitable for power reactor use are made by incorporating a small amount of sulphur into the uranium dioxide before sintering. The increase in grain size achieved results in an improvement in overall efficiency when such pellets are used in a power reactor. (author)

  2. Implications on the sintering process by using zinc stearate as an additive in uranium dioxide green pellets

    International Nuclear Information System (INIS)

    Georgeoni, P.; Deju, R.; Gordes, P.; Turcanu, C.; Dobos, I.

    1980-01-01

    The mode of decomposition and removing of zinc stearate from uranium dioxide matrix into hydrogen atmosphere, as well as zinc stearate quantity and green density influence on residual carbon removing are described. The work emphasizes the influence that inhomogeneous atmosphere from a sintering furnace may have, sometimes, on the removal kinetics of residual carbon. (author)

  3. Effect of densification additive (Al (OH)3) and U3O8 recycle in sintering UO2-7wt% Gd2O3 fuel pellets

    International Nuclear Information System (INIS)

    Santos, L.R.; Riella, H.G.

    2009-01-01

    The nuclear fuels are the consumable parts of nuclear reactors, and this has several consequences. From an economic point of view, it is important to keep the fuel into reactor for long time. In this context the use of burnable poison, as advanced fuel based in gadolinium oxide dispersed in a uranium oxide matrix, is a technological solution adopted worldwide. The function of the burnable poison fuels is to control the neutrons population in the nuclear reactors cores during its start up and the beginning of the fuel burning cycle to extending their use. In consequence of the use of this advanced fuel, the nuclear reactors can operate with higher rate of power, optimizing the use of the nuclear fuels. The objective of the present work is to show the development of UO 2 -7wt% Gd 2 O 3 burnable absorber containing pellets by using mechanical blending of (Al(OH) 3 ) densification additive and U 3 O 8 of the recycling of nuclear fuel scrap. In the procedures, the gadolinium content of 7 wt% was established as a consequence of the P and D Cooperation Programmer firmed by the CTMSP and the INB, looking for the nationalization of this type of nuclear fuel used in the Nuclear Facility of Angra 2. The experimental results permit to observe the effectiveness action of the compound Al(OH) 3 as a additive to promote the increasing in the densification of the (U-Gd)O 2 pellets during its sintering, when amounts of recycle are recycled to the production processing up to 10 wt%, and when 0,20 wt% of Al(OH) 3 is used as additive. (author)

  4. Determination of rare earth elements, hafnium and cadmium in sintered pellets of mixed thorium and uranium oxides by neutron activation

    International Nuclear Information System (INIS)

    Cardoso, S.N.M.

    1987-01-01

    This work shows the development of a method for determination of the rare-earth elements (Eu, Sm, Dy and Gd), Hf and Cd contents in sinterized U and Th mixed oxides by neutron activation analysis. The sample is dissolved in nitric/fluoridric (0,1% HF) medium, to dryness and redissolved in 6N HCl solution. The Hf is extracted into organic phase (0,5 M TTA/benzene), irradiated and analysed through 181 Hf isotope energy peak. The aqueous phase is treated with NH 4 OH for the precipitation of hidroxides. Then, these are dissolved in 6N HNO 3 solution. The extraction of U and Th is made in two steps, one with TBP/CCl 4 and another with 0,5 M TTA/C 6 H 6 . Then the rare-earth elements and Cd are irradiated and determined by gamma spectrometry. (author) [pt

  5. Fuel pellets of various shapes- fabrication experience

    International Nuclear Information System (INIS)

    Ramachandran, R.; Nair, M.R.; Majumdar, S.; Purushotham, D.S.C.

    1996-10-01

    Sintered uranium oxide and mixed oxide pellets are extensively used as nuclear reactor fuel. The shape of the fuel-pellets influence greatly their in-reactor performance. Fuel pellets of various shapes were prepared in Radiometallurgy Division to study their fabricability and in-reactor performance. This paper presents the experience in fabricating these fuel pellets. (author)

  6. Consolidated waste forms: glass marbles and ceramic pellets

    International Nuclear Information System (INIS)

    Treat, R.L.; Rusin, J.M.

    1982-05-01

    Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured from a melter in a continuous stream into a marble-making device. Marbles were produced at PNL on a vibratory marble machine at rates as high as 60 kg/h. Other marble-making concepts were also investigated. The marble process, including a lead-encapsulation step, was judged as one of the more feasible processes for immobilizing high-level wastes. To produce ceramic pellets, a series of processing steps are required, which include: spray calcining - to dry liquid wastes to a powder; disc pelletizing - to convert waste powders to spherical pellets; sintering - to densify pellets and cause desired crystal formation. These processing steps are quite complex, and thereby render the ceramic pellet process as one of the least feasible processes for immobilizing high-level wastes

  7. Fuel pellet

    International Nuclear Information System (INIS)

    Watarumi, Kazutoshi.

    1986-01-01

    Purpose: To improve thermal stability particularly thermal shock resistance and at the same time, improve the holdback characteristics of fission products (FP) by coarsening the crystal particle size within a given range of dimensional density and submersion density. Constitution: For improvement of the holding characteristics of fission products (FP), it is generally required to enlarge the particle size, and for improvement of the thermal shock resistance, it is necessary to increase the number of open pores such as initial cracks or gaps. The dimensional density of a pellet (division of pallet weight by its volume) is set to 93 - 96 % of its theoretical density, and the submersion density (to be obtained from the effective volume calculated by using the Archimedes' principle under the condition where water invades in the pore section of the pallet) is set to 97 - 99 % of its theoretical density. The crystal particle size is given in the range of 60 - 150 μm. Voild forming agent is added to the pellet with matrices of small particle size and comparatively less number of open pores. The pallet is sintered for long hours at high temperatures or crystal particle growing agent is added to the pellet to cope with coarsening of the crystal particle size of matrices. (Seki, T.)

  8. Mox pellet reference material

    International Nuclear Information System (INIS)

    Perolat, J.P.

    1991-01-01

    A first batch of MOX pellets certified in plutonium and uranium has been prepared and characterised in France to meet the needs of laboratories which are engaged upon destructive analysis for safeguards purposes especially in fuel fabrication plants. The pellets sintering has been obtained in a special fabrication to achieve an homogeneity better than 0.1%. The plutonium and uranium characterisation by chemical analysis has been carried out by two laboratories using at least two different methods. 1 fig., 5 refs

  9. Uranium dioxide pellets

    International Nuclear Information System (INIS)

    Zawidzki, T.W.

    1982-01-01

    A process for the preparation of a sintered, high density, large crystal grain size uranium dioxide pellet is described which involves: (i) reacting a uranyl nitrate of formula UO 2 (NO 3 ) 2 .6H 2 O with a sulphur source, at a temperature of from about 300 deg. C to provide a sulphur-containing uranium trioxide; (ii) reacting the thus-obtained modified uranium trioxide with ammonium nitrate to form an insoluble sulphur-containing ammonium uranate; (iii) neutralizing the thus-formed slurry with ammonium hydroxide to precipitate out as an insoluble ammonium uranate the remaining dissolved uranium; (iv) recovering the thus-formed precipitates in a dry state; (v) reducing the dry precipitate to UO 2 , and forming it into 'green' pellets; and (vi) sintering the pellets in a hydrogen atmosphere at an elevated temperature

  10. Sintered-to-size FBR fuel

    International Nuclear Information System (INIS)

    Rasmussen, D.E.; Schaus, P.S.

    1984-04-01

    Fabrication of sintered-to-size PuO 2 -UO 2 fuel pellets was completed for testing of proposed FBR product specifications. Approximately 6000 pellets were fabricated to two nominal diameters and two densities by cold pressing and sintering to size. Process control and correlation between test and production batches are discussed

  11. Nuclear fuel pellet loading machine

    International Nuclear Information System (INIS)

    Kee, R.W.; Denero, J.V.

    1975-01-01

    An apparatus for loading nuclear fuel pellets on trays for transfer in a system is described. A conveyor supplies pellets from a source to a loading station. When the pellets reach a predetermined position at the loading station, a manual or automatically operated arm pushes the pellets into slots on a tray and this process is repeated until pellet sensing switches detect that the tray is full. Thereupon, the tray is lowered onto a belt or other type conveyor and transferred to other apparatus in the system, such as a furnace for sintering, and in some cases, reduction of UO 2 . 2 to UO 2 . The pellets are retained on the tray and subsequently loaded directly into fuel rods to be used in the reactor core. (auth)

  12. [Pelletization of melts and liquids].

    Science.gov (United States)

    Rabisková, Miloslava

    2011-04-01

    During the second half of the last century, pelletization methods based on wetting were developed, e.g. agglomeration in coating pans, pelletization plates or fluid-bed equipment, layering of the drug in solution or suspension on inactive spherical cores, extrusion/spheronization and later on also rotoagglomeration in rotogranulators or rotoprocessors. These technologies have become a requisite part of industrial production of solid dosage forms. At present, numerous experimental papers deal with pellet preparation from melts and liquids. These new pelletization methods are the topic of the present article. Pellet preparation from melts is represented by three methods, i.e. fluid hot melt agglomeration, hot melt extrusion, and freeze pelletization. Jet cutting and cryopelletization are the techniques dealing with pellet preparation from liquids.

  13. Method of manufacturing sintered nuclear fuel

    International Nuclear Information System (INIS)

    Watarumi, Kazutoshi.

    1984-01-01

    Purpose: To obtain composite pellets with an improved strength. Method: A core mainly composed of fuel materials is previously prepared, embedded into the central portion of a pellet, silted therearound with cladding material, and then pressmolded and sintered. For instance, a rugby-ball like core body with the maximum outer diameter of 6 mm and the height of 6 mm is made by compressive molding with uranium dioxide powder, then coating material comprising the same powder incorporated with 0.1 % by weight of SiC fibers is filled around the core body, which is molded into a composite pellet by means of pressing and then sintered at 1600 0 C, to obtain a sintered pellet of 93.5 % theoretical density. As the result of the compression test for the pellet, it showed a strength greater by 15 % than that of the similar mono-layer pellet. (Kamimura, M.)

  14. Effect of densification additive (Al (OH){sub 3}) and U{sub 3}O{sub 8} recycle in sintering UO{sub 2}-7wt% Gd{sub 2}O{sub 3} fuel pellets

    Energy Technology Data Exchange (ETDEWEB)

    Santos, L.R. [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil)], e-mail: lauro@ctmsp.mar.mil.br, e-mail: lrsantos@ipen.br; Riella, H.G. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Quimica e Alimentos], e-mail: riella@enq.ufsc.br

    2009-07-01

    The nuclear fuels are the consumable parts of nuclear reactors, and this has several consequences. From an economic point of view, it is important to keep the fuel into reactor for long time. In this context the use of burnable poison, as advanced fuel based in gadolinium oxide dispersed in a uranium oxide matrix, is a technological solution adopted worldwide. The function of the burnable poison fuels is to control the neutrons population in the nuclear reactors cores during its start up and the beginning of the fuel burning cycle to extending their use. In consequence of the use of this advanced fuel, the nuclear reactors can operate with higher rate of power, optimizing the use of the nuclear fuels. The objective of the present work is to show the development of UO{sub 2}-7wt% Gd{sub 2}O{sub 3} burnable absorber containing pellets by using mechanical blending of (Al(OH){sub 3}) densification additive and U{sub 3}O{sub 8} of the recycling of nuclear fuel scrap. In the procedures, the gadolinium content of 7 wt% was established as a consequence of the P and D Cooperation Programmer firmed by the CTMSP and the INB, looking for the nationalization of this type of nuclear fuel used in the Nuclear Facility of Angra 2. The experimental results permit to observe the effectiveness action of the compound Al(OH){sub 3} as a additive to promote the increasing in the densification of the (U-Gd)O{sub 2} pellets during its sintering, when amounts of recycle are recycled to the production processing up to 10 wt%, and when 0,20 wt% of Al(OH){sub 3} is used as additive. (author)

  15. Commercial development of a new process of uraniferous ore sintering by pelletizing before dump leaching (wet process) application to a very clayey ore of Nord-Aquitaine

    International Nuclear Information System (INIS)

    Videau, G.; Roche, M.

    1990-01-01

    Much of the French uranium ore contains clay of sedimentary origin or derived from the alteration of rocks of the granite type. During a dump leaching operation by a wet process, these clays reduce the percolation rates and sometimes the percolation rates are so low that the very essence of the dump leaching operation can be called in question. This problem arises particularly for the treatment of the ore of Nord-Aquitaine. The results of tests, carried out at the SEPA in Bessines, have shown that after pelletizing clayey ores with sodium silicate in the presence of sulphuric acid for the polymerization of the silicate, the percolation rates were much increased. This new method was successfully applied, from a laboratory column to a pilot dump of 500 tonnes for the very clayey ore of Nord-Aquitaine. This ore of low grade (approx. 1000 ppm of U) seems to be difficult to upgrade by any other method of treatment in the present economic context [fr

  16. Method of manufacturing nuclear fuel pellet

    International Nuclear Information System (INIS)

    Oguma, Masaomi; Masuda, Hiroshi; Hirai, Mutsumi; Tanabe, Isami; Yuda, Ryoichi.

    1989-01-01

    In a method of manufacturing nuclear fuel pellets by compression molding an oxide powder of nuclear fuel material followed by sintering, a metal nuclear material is mixed with an oxide powder of the nuclear fuel material. As the metal nuclear fuel material, whisker or wire-like fine wire or granules of metal uranium can be used effectively. As a result, a fuel pellet in which the metal nuclear fuel is disposed in a network-like manner can be obtained. The pellet shows a great effect of preventing thermal stress destruction of pellets upon increase of fuel rod power as compared with conventional pellets. Further, the metal nuclear fuel material acts as an oxygen getter to suppress the increase of O/M ratio of the pellets. Further, it is possible to reduce the swelling of pellet at high burn-up degree. (T.M.)

  17. Fuel pellet

    International Nuclear Information System (INIS)

    Hayashi, K.

    1980-01-01

    Fuel pellet for insertion into a cladding tube in order to form a fuel element or a fuel rod. The fuel pellet has got a belt-like projection around its essentially cylindrical lateral circumferential surface. The upper and lower edges in vertical direction of this belt-like projection are wave-shaped. The projection is made of the same material as the bulk pellet. Both are made in one piece. (orig.) [de

  18. Influence of green pellet properties on pelletizing of magnetite iron ore

    OpenAIRE

    Forsmo, Seija

    2007-01-01

    Magnetite iron ore green pellets are produced by balling moist concentrates to green pellets, which are then dried, oxidized to hematite, sintered, cooled and transported to steelmaking plants. The existing theory for balling is based on the capillary theory, but its applicability under industrial balling conditions is unclear. The aim of this study has been to clarify the principal mechanisms controlling the properties of iron ore green pellets. Special attention has been paid to studying ho...

  19. Westinghouse new advanced developed doped pellet

    International Nuclear Information System (INIS)

    Backmann, Karin; Valizadeh, Sima; Hallstadius, Lars; Wright, Jonathan; Widegren, Hans; Roennberg, Gunnar

    2008-01-01

    Westinghouse has developed ADOPT (Advanced Doped Pellet Technology) UO 2 fuel containing additions of Cr 2 O 3 and Al 2 O 3 . Our paper presents results from the extensive investigation program which covered examinations of doped and reference standard pellets both in the manufactured and irradiated states. The additives facilitate pellet densification during sintering and enlarge the pellet grain size. The in-reactor performance of the ADOPT pellets has been investigated in pool-side and hot cell Post Irradiation Examinations (PIEs), as well as in the Studsvik R2 test reactor. The investigations have identified three areas of improved operational behavior: Reduced fission gas release, improved Pellet Cladding Interaction (PCI) performance thanks to increased pellet plasticity, and higher resistance against post failure degradation. Fuel segments have been exposed to ramp tests and enhanced power steady-state operation in the Studsvik R2 reactor after base-irradiation to above 30 MWd/kgU in a commercial BWR. ADOPT reveals up to 30% lower fission gas release than standard UO 2 pellets. The fuel degradation in an erosion tests under irradiation, showed that ADOPT pellets have a reduced rate of fuel washout, as compared to standard UO 2 pellets. Fuel rods with ADOPT pellets have been irradiated in several LWRs since 1999, including two full SVEA Optima2 reloads in 2005. (orig.)

  20. Pellet injector for diagnostics purposes

    International Nuclear Information System (INIS)

    Lang, P.T.; Cierpka, P.; Egorov, S.M.; Kass, T.; Kuteev, B.V.; Reznichenko, P.V.; Sergeev, V.Yu.; Vetter, H.; Weber, G.

    1994-07-01

    We report the design, construction and the testbed results for a novel compact gas gun injector for solid diagnostic pellets of different sizes and materials. The injector was optimized for the diagnostic requirements of the ASDEX Upgrade tokamak, yielding the possibility of a widely varying deposition profile of ablated material inside the plasma. This allows variation of the pellet velocity and the total number of injected atoms. The use of different propellant gases (He, N 2 , H 2 ) results in an accessible velocity range from about 150 m/s to more than 600 m/s in the case of spherical carbon pellets with masses ranging from 2x10 18 to 10 20 atoms. Both the scattering angle (∝1 ) and the maximum propellant gas throughput to the tokamak (less than 10 16 gas particles) were found to be sufficiently low. The injector provided both high efficiency (≥85%) and high reliability during the whole testbed operation period and also during the first injection experiments performed on ASDEX Upgrade. The pellet velocities achieved for different propellant gas pressures, pellet diameters, and pellet materials were analyzed. We found that, although the pellet diameters range from 0.45 to 0.85 times the barrel diameter, the pellet acceleration is mostly caused by gas drag. Pellet velocities in excss of those calculated on the basis of the gas drag model were observed. Additional acceleration that increases with the pellet diameter contrary to the gas drag model may be explained by the influence of the pellet on the gas dynamics in the barrel. (orig.)

  1. Preparations of high density (Th,U)O2 pellets

    International Nuclear Information System (INIS)

    Akabori, Mitsuo; Ikawa, Katsuichi

    1986-07-01

    Preparations of high density and homogeneous (Th,U)O 2 pellets by a powder metallurgy method were examined. (Th,U)O 2 powders were prepared by calcining coprecipitates of ammonium uranate and thorium hydroxide derived from nitrates and mixed sols, and by calcining mixed oxalates precipitated from nitrates. (Th,U)O 2 pellets were characterized with respect to sinterability, lattice parameter, microstructure, homogeneity and stoichiometry. Sintering atmospheres had a significant effect upon all the properties of the derived pellets. The sinterability of (Th,U)O 2 was most favourable in oxidizing and reducing atmospheres for ThO 2 -rich and UO 2 -rich compositions, respectively, and can be enhanced by presence of water vapour in sintering atmospheres. In addition, highly homogeneous (Th,U)O 2 pellets with 99 % in theoretical density were derived from the sol powders. (author)

  2. Density control method for nuclear fuel pellet

    International Nuclear Information System (INIS)

    Wataumi, Kazutoshi.

    1993-01-01

    In a density control for nuclear fuel pellets produced from a raw material powder containing dioxides of uranium or plutonium and oxides of rare earth elements, trimetal octoxides formed from dioxides or the raw material powder not undergoing thermal hysteresis at higher than 1,000degC are added to the raw material powder. Further, trimetal octoxides obtained by calcining a sintering product of the raw material powder is added in addition the trimetal octoxides of the elements. Furthermore, the density of the nuclear fuel pellet is controlled by two kinds of trimetal octoxides obtained by calcining the sintering products of the dioxides, the raw material powder or the nuclear fuel sintering materials at 350 to 800degC. Since trimetal octoxides powder derived from the raw material powder is used as a density increasing additive for the nuclear fuel pellets, it is advantageous in view of stable operation, different from a conventional method of controlling molding condition and sintering condition, and since the trimetal octoxides powder derived from the sintering product is also used, various kinds of density control for nuclear fuel pellets can be conducted. (N.H.)

  3. Self-Consolidation Mechanism Of Porous Ti-6Al-4V Implant Prototypes Produced By Electro-Discharge-Sintering Of Spherical Ti-6Al-4V Powders

    Directory of Open Access Journals (Sweden)

    Lee W.H.

    2015-06-01

    Full Text Available Electro-Discharge-Sintering (EDS was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 – 150 μm, that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 – 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.

  4. TiO2 doped UO2 fuels sintered by spark plasma sintering

    Science.gov (United States)

    Yao, Tiankai; Scott, Spencer M.; Xin, Guoqing; Lian, Jie

    2016-02-01

    UO2 fuels doped with oxide additives Cr2O3 and TiO2 display larger grain size, improving fission product retention capability and thus accident tolerance. Spark plasma sintering (SPS) was applied to consolidate TiO2-doped UO2 fuel pellets with 0.5 wt % dopant concentration, above its solubility, in order to induce eutectic phase formation and promote sintering kinetics. The grain size can reach 80 μm by sintering at 1700 °C for 20 min, and liquid U-Ti-O eutectic phase occurs at the triple junction of grain boundaries and significantly improves grain growth during sintering. The oxide additive also impedes the reduction of the initial hyperstoichiometric fuel powders to more stoichiometric fuel pellets upon SPS process. Thermal-mechanical properties of the sintered doped fuel pellets including thermal conductivity and hardness are measured and compared with undoped fuel pellets. The enlarged grain size (80 μm) and densification within short sintering duration highlight the immense possibility of SPS in fabricating large grained UO2 fuel pellets to improve fuel performance.

  5. Sinterable powders

    International Nuclear Information System (INIS)

    Zanghi, J.S.; Kasprzyk, M.R.

    1979-01-01

    A description is given of sinterable powders and methods of producing sintered products using such powders. The powders consist of (a) a particulate ceramic material, e.g. SiC, having specified particle size and surface area; (b) a carbon source material, e.g. sugar or a phenol-formaldehyde resin; and (c) a residue from a solution of H 3 BO 3 , B 2 O 3 , or mixtures of these as sintering aid. (U.K.)

  6. Fabrication of ThO2, UO2, and PuO2-UO2 pellets

    International Nuclear Information System (INIS)

    Rasmussen, D.E.; Jentzen, W.R.; McCord, R.B.

    1978-01-01

    Fabrication of ThO pellets for EBR-II irradiation testing and fabrication of UO 2 and PuO 2 -UO 2 pellets for United Kingdom Prototype Fast Reactor (PFR) irradiation testing is discussed. Effect of process parameters on density and microstructure of pellets fabricated by the cold press and sinter technique is reviewed

  7. Fish pelleting

    African Journals Online (AJOL)

    PUBLICATIONS1

    lion tonnes (Punch 2014). The increasing growth in .... CAS = critical stress (Pa) particulate density ..... Design and fabrication of fish meal pellet processing machine ... 59. T a b le 1. : W eig h t, efficien cy a n d d ry n ess o. f p ro cessed fish m ea. l p ellets. S a m p le. Tested. W eig h. t o f. In g red ien ts. (K g. ) W eig h. t o.

  8. Processing of surrogate nuclear fuel pellets for better dimensional control with dry bag isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Hoggan, Rita E., E-mail: Rita.hoggan@inl.gov; Zuck, Larry D., E-mail: Larry.zuck@inl.gov; Cannon, W. Roger, E-mail: cannon@rutgers.edu; Lessing, Paul A., E-mail: p.a.l.2@hotmail.com

    2016-12-15

    A study of improved methods of processing fuel pellets was undertaken using ceria and zirconia/yttria/alumina as surrogates. Through proper granulation, elimination of fines and vertical vibration (tapping) of the parts bag prior to dry bag isostatic pressing (DBIP), reproducibility of diameter profiles among multiple pellets of ceria was improved by almost an order of magnitude. Reproducibility of sintered pellets in these studies was sufficient to allow pellets to be introduced into the cladding with a gap between the pellet and cladding on the order of 50 μm to 100 μm but not a uniform gap with tolerance of ±12 μm as is currently required. Deviation from the mean diameter along the length of multiple pellets, and deviation from roundness, decreased after sintering. This is not generally observed with dry pressed pellets. Sintered shrinkage was uniform to ±0.05% and thus, as an alternative, pellets may be machined to tolerance before sintering, thus avoiding the waste associated with post-sinter grinding. - Highlights: • Three methods of granule preparation for two different powder sources were outlined and compared using tap density curves. • A dry bag isostatic press was used to fabricate pellets and longer rods. Thus longer pellets could be fabricated by this technique. • Vertical vibrations to pack granules decreased variation in dimensions from pellet to pellet by a factor of nine. • Sintering shrinkage varied by only 0.1% along the length of a rod. Thus green machining prior to sintering could result in tight tolerances.

  9. Characterization and property evaluation of (Th–3.75U)O{sub 2+x} fuel pellets fabricated by impregnated agglomerate pelletization (IAP) process

    Energy Technology Data Exchange (ETDEWEB)

    Baghra, C.; Sathe, D.B.; Prakash, A.; Mishra, A.K.; Afzal, Mohd [Advanced Fuel Fabrication Facility (AFFF), Bhabha Atomic Research Center (BARC), Tarapur Complex 401502, Maharashtra (India); Panakkal, J.P., E-mail: panakkal@barctara.gov.in [Advanced Fuel Fabrication Facility (AFFF), Bhabha Atomic Research Center (BARC), Tarapur Complex 401502, Maharashtra (India); Kamath, H.S. [Advanced Fuel Fabrication Facility (AFFF), Bhabha Atomic Research Center (BARC), Tarapur Complex 401502, Maharashtra (India)

    2013-06-15

    Highlights: ► Characterization of (Th–3.75%U)O{sub 2+x} pellet fabricated by a new technique i.e., impregnated agglomerate pelletization (IAP). ► Comparison with pellets fabricated by powder to pellet (POP) and coated agglomerate pelletization processes. ► Solid solution was more complete in POP and IAP pellets. ► Uranium distribution was less uniform in the pellets fabricated by the CAP route. -- Abstract: Impregnated agglomerate pelletization (IAP) process has been developed by Advanced Fuel Fabrication Facility (AFFF), Tarapur for the fabrication of (Th–3.75U)O{sub 2+x} mixed oxide fuel for Indian advanced heavy water reactors (AHWR). In this process, ThO{sub 2} spheroids were impregnated with uranyl nitrate solution and the resultant mixture was compacted to form green pellets which were sintered in the oxidizing atmosphere to obtain high density (Th–3.75%U)O{sub 2+x} pellets. An attempt has been made in this paper to characterize the pellets fabricated by IAP route. The characterization of the sintered IAP pellets was made by X-ray diffraction, EPMA, alpha autoradiography, chemical analysis, O/M ratio, immersion density and optical microscopy. The characteristics of (Th–U)O{sub 2} pellets fabricated by impregnated agglomerate pelletization (IAP) were also compared with those fabricated by coated agglomerate pelletization (CAP), and conventional powder pellet (POP) processes. In case of pellets fabricated by IAP route, XRD data showed the presence of single fluorite phase. The uranium concentration and grain size distribution were found to be uniform throughout the pellet. These phase characteristics were also found to be more uniform in pellets made by both IAP and POP processes as compared to pellets fabricated using the CAP process.

  10. Characterization and property evaluation of (Th–3.75U)O2+x fuel pellets fabricated by impregnated agglomerate pelletization (IAP) process

    International Nuclear Information System (INIS)

    Baghra, C.; Sathe, D.B.; Prakash, A.; Mishra, A.K.; Afzal, Mohd; Panakkal, J.P.; Kamath, H.S.

    2013-01-01

    Highlights: ► Characterization of (Th–3.75%U)O 2+x pellet fabricated by a new technique i.e., impregnated agglomerate pelletization (IAP). ► Comparison with pellets fabricated by powder to pellet (POP) and coated agglomerate pelletization processes. ► Solid solution was more complete in POP and IAP pellets. ► Uranium distribution was less uniform in the pellets fabricated by the CAP route. -- Abstract: Impregnated agglomerate pelletization (IAP) process has been developed by Advanced Fuel Fabrication Facility (AFFF), Tarapur for the fabrication of (Th–3.75U)O 2+x mixed oxide fuel for Indian advanced heavy water reactors (AHWR). In this process, ThO 2 spheroids were impregnated with uranyl nitrate solution and the resultant mixture was compacted to form green pellets which were sintered in the oxidizing atmosphere to obtain high density (Th–3.75%U)O 2+x pellets. An attempt has been made in this paper to characterize the pellets fabricated by IAP route. The characterization of the sintered IAP pellets was made by X-ray diffraction, EPMA, alpha autoradiography, chemical analysis, O/M ratio, immersion density and optical microscopy. The characteristics of (Th–U)O 2 pellets fabricated by impregnated agglomerate pelletization (IAP) were also compared with those fabricated by coated agglomerate pelletization (CAP), and conventional powder pellet (POP) processes. In case of pellets fabricated by IAP route, XRD data showed the presence of single fluorite phase. The uranium concentration and grain size distribution were found to be uniform throughout the pellet. These phase characteristics were also found to be more uniform in pellets made by both IAP and POP processes as compared to pellets fabricated using the CAP process

  11. Sintering uranium oxide using a preheating step

    International Nuclear Information System (INIS)

    Jensen, N.J.; Nivas, Y.; Packard, D.R.

    1977-01-01

    Compacted pellets of uranium oxide or uranium oxide with one or more additives are heated in a kiln in a process having a preheating step, a sintering step, a reduction step, and a cooling step in a controlled atmosphere. The process is practiced to give a range of temperature and atmosphere conditions for obtaining optimum fluoride removal from the compacted pellets along with optimum sintering in a single process. The preheating step of this process is conducted in a temperature range of about 600 0 to about 900 0 C and the pellets are held for at least twenty min, and preferably about 60 min, in an atmosphere having a composition in the range of about 10 to about 75 vol % hydrogen with the balance being carbon dioxide. The sintering step is conducted at a temperature in the range of about 900 0 C to 1500 0 C in the presence of an atmosphere having a composition in the range of about 0.5 to about 90 vol % hydrogen with the balance being carbon dioxide. The reduction step reduces the oxygen to metal ratio of the pellets to a range of about 1.98 to 2.10:1 and this is accomplished by gradually cooling the pellets for about 30 to about 120 min from the temperature of the sintering step to about 1100 0 C in an atmosphere of about 10 to 90 vol % hydrogen with the balance being carbon dioxide. Thereafter the pellets are cooled to about 100 0 C under a protective atmosphere, and in one preferred practice the same atmosphere used in the reduction step is used in the cooling step. The preheating, sintering and reduction steps may also be conducted with their respective atmospheres having an initial additional component of water vapor and the water vapor can comprise up to about 20 vol %

  12. Nuclear fuel pellet manufacturing method

    International Nuclear Information System (INIS)

    Matsuda, Tetsushi.

    1995-01-01

    An uranium oxide powder is compression-molded to form a compressed powder product, and the compressed powder product is sintered to form a ceramic nuclear fuel pellet. In this case, the uranium oxide powder to be supplied to a press hole for compression molding is exposed to an atmosphere of one of vapors of benzene, hexane, acetone, acetic acid, ethanol or water, or an atmosphere of a vapor mixture of several kinds of them. Thereafter, uranium oxide powder is compression molded in the same vapor atmosphere. Since the vapor atmosphere is used as an aid for a molding adjuvant or a substitute thereof, lowering of pellet density due to residual molding adjuvant can be prevented. In addition, the vapor atmosphere is penetrated uniformly between the uranium oxide powder to suppress density fluctuation of the compressed powder material thereby enabling to unify the shrinking rate. (I.N.)

  13. UO2 pellet and manufacturing method

    International Nuclear Information System (INIS)

    Komada, Kiichi; Nishinaka, Keiji; Adachi, Kazunori; Fujiwara, Shuji.

    1995-01-01

    The present invention concerns an uranium dioxide pellet having a large crystal grain size. The grain size of the pellet is enlarged to increase the distance of an FP gas generated in the crystal grain to reach the grain boundary and, as a result, decrease the releasing speed of the FP gas. A UO 2 powder having a specific surface area of from 5 to 50m 2 /g is used as a starting powder in a step of forming a molding product, and chlorine or a chlorine compound is added in such an amount that the chlorine content in the UO 2 pellet is from 3 to 25ppm, in one of a production step, a molding step or a sintering step for UO 2 powder. With such procedures, a UO 2 pellet having a large crystal grain size can be prepared with good reproducibility. (T.M.)

  14. Fabrication of uranium dioxide ceramic pellets with controlled porosity from oxide microspheres

    Science.gov (United States)

    Remy, E.; Picart, S.; Delahaye, T.; Jobelin, I.; Dugne, O.; Bisel, I.; Blanchart, P.; Ayral, A.

    2014-05-01

    This study concerns the fabrication of uranium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Details are given about oxide microsphere synthesis and particularly about loading operation and heat treatments. The fabrication of ceramic pellets is also described and discussed. Results showed that this process allows the preparation of either dense or porous pellets by mixing U3O8 and UO2-like microspheres before pressing and sintering.

  15. Fabrication of uranium dioxide ceramic pellets with controlled porosity from oxide microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Remy, E. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Picart, S., E-mail: sebastien.picart@cea.fr [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Delahaye, T. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Jobelin, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Dugne, O. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Bisel, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Blanchart, P. [Heterogeneous Materials Research Group, Centre Européen de la Céramique, F-87068 Limoges (France); Ayral, A. [Institut Européen des Membranes, UMR 5635 CNRS-ENSCM-UM2, University of Montpellier, F-34095 Montpellier cedex 5 (France)

    2014-05-01

    This study concerns the fabrication of uranium oxide pellets using the powder-free process called Calcined Resin Microsphere Pelletization (CRMP). Details are given about oxide microsphere synthesis and particularly about loading operation and heat treatments. The fabrication of ceramic pellets is also described and discussed. Results showed that this process allows the preparation of either dense or porous pellets by mixing U{sub 3}O{sub 8} and UO{sub 2}-like microspheres before pressing and sintering.

  16. Nano and micro U1-xThxO2 solid solutions: From powders to pellets

    Science.gov (United States)

    Balice, Luca; Bouëxière, Daniel; Cologna, Marco; Cambriani, Andrea; Vigier, Jean-François; De Bona, Emanuele; Sorarù, Gian Domenico; Kübel, Christian; Walter, Olaf; Popa, Karin

    2018-01-01

    Nuclear fuels production, structural materials, separation techniques, and waste management, all may benefit from an extensive knowledge in the nano-nuclear technology. In this line, we present here the production of U1-xThxO2 (x = 0 to 1) mixed oxides nanocrystals (NC's) through the hydrothermal decomposition of the oxalates in hot compressed water at 250 °C. Particles of spherical shape and size of about 5.5-6 nm are obtained during the hydrothermal decomposition process. The powdery nanocrystalline products were consolidated by spark plasma sintering into homogeneous mixed oxides pellets with grain sizes in the 0.4 to 5.5 μm range. Grain growth and mechanical properties were studied as a function of composition and size. No grain size effect was observed on the hardness or elastic modulus.

  17. Quality properties of fuel pellets from forest biomass

    Energy Technology Data Exchange (ETDEWEB)

    Lehtikangas, P.

    1999-07-01

    Nine pellet assortments, made of fresh and stored sawdust, bark and logging residues (a mixture of Norway spruce and Scots pine) were tested directly after production and after 5 months of storage in large bags (volume about 1 m{sup 3} loose pellets) for moisture content, heating value and ash content. Dimensions, bulk density, density of individual pellets and durability were also determined. Moreover, sintering risk and contents of sulphur, chlorine, and lignin of fresh pellets were determined. It is concluded that bark and logging residues are suitable raw materials for pellets production, especially regarding durability and if the ash content is controlled. Pellets density had no effect on its durability, unlike lignin content which was positively correlated. The pellets had higher ash content and lower calorific heating value than the raw materials, probably due to loss of volatiles during drying. In general, the quality changes during storage were not large, but notable. The results showed that storage led to negative effects on durability, especially on pellets made of fresh materials. The average length of pellets was decreased due to breakage during storage. Microbial growth was noticed in some of the pellet assortments. Pellets made out of fresh logging residues were found to be weakest after storage. The tendency to reach the equilibrium with the ambient moisture content should be taken into consideration during production due to the risk of decreasing durability.

  18. Pellets - A fuel with a future

    International Nuclear Information System (INIS)

    2004-01-01

    This special brochure presents a series of articles on the topic of wood pellets as a fuel of the future. Dr. Walter Steinmann, director of the Swiss Federal Office of Energy (SFOE) introduces the topic, stressing that the Swiss Confederation and the Cantons are supporting efforts to increase the sustainable use of wood fuels. Further articles take a closer look at pellets and their form. Pellets-fired heating units are introduced as a viable alternative to traditional oil-fired units. Tips are presented on the various ways of storing pellets. Quality-assurance aspects are examined and manufacturers and distributors of wood pellets are listed. A further article takes a closer look at a large Swiss manufacturer of pellets and describes the production process used as well as the logistics necessary for the transportation of raw materials and finished products. The brochure also presents a selection of pellet ovens and heating systems from various manufacturers. A further article illustrates the use of pellets as a means of heating apartment blocks built to the MINERGIE low-energy-consumption standard. In the example quoted, the classic combination of solar energy for the pre-heating of hot water and pellets for the central heating and hot water supply is used. The use of a buried spherical tank to store pellets - and thus the saving of space inside the building - is described in a further article that takes a look at the refurbishment of the heating system in a single-family home. Finally, various contributions presented at the Pellets Forum held in Berne in November 2003 are summarised in a short article

  19. Sintering, microstructural and dilatometric studies of combustion synthesized Synroc phases

    International Nuclear Information System (INIS)

    Muthuraman, M.; Patil, K.C.; Senbagaraman, S.; Umarji, A.M.

    1996-01-01

    Sintering, microstructure, and linear thermal expansion properties of Synroc-B and constituent phases, viz. perovskite CaTiO 3 , zirconolite ZrTi 2 O 7 , hollandite (ideal formula BaAl2Ti 6 O 16 ) have been investigated. Synroc-B powder when pelletized and sintered at 1250 C for 2 h achieved >95% theoretical density. Sintered Synroc-B has a linear thermal expansion coefficient α of 8.72 x 10 -6 K -1 and Vicker's microhardness 9.88 GPa. The linear thermal expansion curves did not show any hysteresis indicating the absence of microcracking in the sintered bodies

  20. Pellet injectors for JET

    International Nuclear Information System (INIS)

    Andelfinger, C.; Buechl, K.; Lang, R.S.; Schilling, H.B.; Ulrich, M.

    1981-09-01

    Pellet injection for the purpose of refuelling and diagnostic of fusion experiments is considered for the parameters of JET. The feasibility of injectors for single pellets and for quasistationary refuelling is discussed. Model calculations on pellet ablation with JET parameters show the required pellet velocity ( 3 ). For single pellet injection a light gas gun, for refuelling a centrifuge accelerator is proposed. For the latter the mechanical stress problems are discussed. Control and data acquisition systems are outlined. (orig.)

  1. Wax-based sustained release matrix pellets prepared by a novel freeze pelletization technique I. Formulation and process variables affecting pellet characteristics.

    Science.gov (United States)

    Cheboyina, Sreekhar; Wyandt, Christy M

    2008-07-09

    A novel freeze pelletization technique was evaluated for the preparation of wax-based matrix pellets. Pellets containing either theophylline or diltiazem HCl were prepared using various waxes. In this technique, molten waxes along with a dispersed active ingredient were introduced as droplets into an inert and immiscible column of liquid to form pellets. An 80% (w/w) aqueous glycerol solution was found to be the most suitable column liquid for preparing spherical wax pellets. The physical stability of the molten wax suspensions was substantially improved by the addition of a 5% (w/w) colloidal silica gel. Pellet size obtained was directly proportional to the cubic root of the outer radius of the needle tip used to form pellets. Pellet size increased as the ratio of interfacial tension (gamma(LL)) to the density difference (Deltarho) between the molten matrix and the column liquid increased. Moreover, an increase in the drug load of theophylline increased the pellet size. However, an addition of a surfactant to the matrix slightly decreased the pellet size. Microscopic studies indicated that theophylline was homogenously dispersed throughout the matrix and existed in a crystalline state at higher drug loads. The percent drug recoveries ranged from 90.7 to 102.3% with acceptable drug loads up to 20% (w/w). Therefore, wax pellets containing drugs of varying aqueous solubility were successfully prepared using this technique.

  2. Wood pellet seminar

    International Nuclear Information System (INIS)

    Aarniala, M.; Puhakka, A.

    2001-01-01

    The objective of the wood pellet seminar, arranged by OPET Finland and North Karelia Polytechnic, was to deliver information on wood pellets, pellet burners and boilers, heating systems and building, as well as on the activities of wood energy advisors. The first day of the seminar consisted of presentations of equipment and products, and of advisory desks for builders. The second day of the seminar consisted of presentations held by wood pellet experts. Pellet markets, the economy and production, the development of the pellet markets and their problems (in Austria), the economy of heating of real estates by different fuel alternatives, the production, delivery and marketing of wood pellets, the utilization of wood pellet in different utilization sites, the use of wood pellets in detached houses, pellet burners and fireplaces, and conversion of communal real estate houses to use wood pellets were discussed in the presentations. The presentations held in the third day discussed the utilization of wood pellets in power plants, the regional promotion of the production and the use of pellets. The seminar consisted also of visits to pellet manufacturing plant and two pellet burning heating plants

  3. Fluorophotometric determination of uranium: an automated sintering furnace and factors affecting precision

    International Nuclear Information System (INIS)

    Strain, J.E.

    1978-07-01

    The fusion furnace consists of four individually controlled, slotted-tube furnaces that automatically dry, sinter and anneal the fluoride or carbonate pellet used in the fluorometric determination of uranium. The furnace operates in air and prepares approximately 90 pellets per hour for fluorometric measurement. The factors that were thought to affect the precision of the method were investigated. The two factors that seem to be the most influential are (1) the manner in which the sample is loaded onto the pellet; and (2) the surface characteristics of the platinum dish in which the pellet is sintered and measured fluorometrically

  4. Manufacturing method for nuclear fuel pellet

    International Nuclear Information System (INIS)

    Komono, Akira

    1998-01-01

    Upon molding of nuclear fuel pellets, the supply of nuclear fuel powder to a dice is divided to a plurality of stages, and a nuclear fuel powder having higher moldability is supplied to a portion where the density of the powder in the molded product is lower. As a result, the density of the powder of the molded product after molding can be made substantially uniform even in a portion where the molding pressure is low and the density of the powder of the molded product is low. Accordingly, difference of the diameter caused depending on the portion of the pellet after sintering is prevented, so that pellets having substantially uniform diameter can be formed, and the specification of the design can be satisfied. If dice agreed with the aimed diameter is selected based on the degree of shrinkage, a grinding step for making the diameter uniform can be eliminated to attain cost down. (N.H.)

  5. The pellet handbook: the production and thermal utilisation of pellets

    National Research Council Canada - National Science Library

    Obernberger, Ingwald; Thek, Gerold

    2010-01-01

    ...: - International overview of standards for pellets - Evaluation of raw materials and raw material potentials - Quality and properties of pellets - Technical evaluation of the pellet production process...

  6. Integrated analysis of oxide nuclear fuel sintering

    International Nuclear Information System (INIS)

    Baranov, V.; Kuzmin, R.; Tenishev, A.; Timoshin, I.; Khlunov, A.; Ivanov, A.; Petrov, I.

    2011-01-01

    Dilatometric and thermal-gravimetric investigations have been carried out for the sintering process of oxide nuclear fuel in gaseous Ar - 8% H 2 atmosphere at temperatures up to 1600 0 C. The pressed compacts were fabricated under real production conditions of the OAO MSZ with application of two different technologies, so called 'dry' and 'wet' technologies. Effects of the grain size growth after the heating to different temperatures were observed. In order to investigate the effects produced by rate of heating on properties of sintered fuel pellets, the heating rates were varied from 1 to 8 0 C per minute. Time of isothermal overexposure at maximal temperature (1600 0 C) was about 8 hours. Real production conditions were imitated. The results showed that the sintering process of the fuel pellets produced by two technologies differs. The samples sintered under different heating rates were studied with application of scanning electronic microscopy analysis for determination of mean grain size. A simulation of heating profile for industrial furnaces was performed to reduce the beam cycles and estimate the effects of variation of the isothermal overexposure temperatures. Based on this data, an optimization of the sintering conditions was performed in operations terms of OAO MSZ. (authors)

  7. Understanding the Biocompatibility of Sintered Calcium Phosphate with Ratio of [Ca]/[P] = 1.50

    Directory of Open Access Journals (Sweden)

    Feng-Lin Yen

    2012-01-01

    Full Text Available Biocompatibility of sintered calcium phosphate pellets with [Ca]/[P] = 1.50 was determined in this study. Calcium pyrophosphate (CPP phase formed on the sintered pellets immersed in a normal saline solution for 14 d at 37∘C. The intensities of hydroxyapatite (HA reflections in the X-ray diffraction (XRD patterns of the pellets were retrieved to as-sintered state. The pellet surface morphology shows that CPP crystallites were clearly present and make an amorphous calcium phosphate (ACP to discriminate against become to the area of slice join together. In addition, the intensities of the CPP reflections in the XRD patterns were the highest when the pellets were immersed for 28 d. When the CPP powders were extracted from the pellets after immersion in the solution for 14 d, the viability of 3T3 cells remained above 90% for culture times from 1 to 4 d. The pellet surface morphology observed using optical microscopy showed that the cells did not adhere to the bottom of the sintered pellets when cultured for 4 d; however, some CPP phase precipitates were formed, as confirmed by XRD. In consequence, the results suggest that the sintered HA powders are good materials for use in biomedical applications because of their good biocompatibility.

  8. Production variables affecting characteristics of pellets in melt pelletization with wax combination in a laboratory scale spheronizer.

    Science.gov (United States)

    Biswal, Sudarsan; Sahoo, Jagannath; Murthy, Padala Narasimham; Giradkar, Rajesh Pandurang; Das, Subash; Avari, Jasmine Gev

    2009-06-01

    The purpose of the study was to evaluate the suitability of laboratory scale spheronizer for the production of spherical pellets loaded with diltiazem hydrochloride by wax combination. The 1:1 combination of cetyl alcohol and hydrogenated castor oil, as low and high melting point waxes, were used. The various production variables affecting the different characteristics of pellets and the process efficiency were evaluated. Drug loaded pellets were evaluated for drug release in distilled water. Bowl temperature primarily affects the sphericity and adhesion of pellets to the bowl. Mass temperature has a pronounced effect on size, size distribution and sphericity of pellets. Wax concentration affects all characteristics of pellets but adhesion was least affected. The effect of these three variables can be compensated by optimizing the friction plate speed. It has been found that the highest yield of pellets (850--1400 microm) with maximum sphericity can be produced by using 45 degrees C bowl temperature, 52 degrees C mass temperature and 1400 rpm friction plate speed.

  9. Fabrication of 0.5-inch diameter FBR mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    Rasmussen, D.E.; Benecke, M.W.; McCord, R.B.

    1979-01-01

    Large diameter (0.535 inch) mixed oxide fuel pellets for Fast Breeder Reactor application were successfully fabricated by the cold-press-and-sinter technique. Enriched UO 2 , PuO 2 -UO 2 , and PuO 2 -ThO 2 compositions were fabricated into nominally 90% theoretical density pellets for the UO 2 and PuO 2 -UO 2 compositions, and 88% and 93% T.D. for the PuO 2 -ThO 2 compositions. Some processing adjustments were required to achieve satisfactory pellet quality and density. Furnace heating rate was reduced from 200 to 50 0 C/h for the organic binder burnout cycle for the large, 0.535-inch diameter pellets to eliminate pellet cracking during sintering. Additional preslugging steps and die wall lubrication during pressing were used to eliminate pressing cracks in the PuO 2 -ThO 2 pellets

  10. Electric Field-Assisted Pressureless Sintering of Ceramic Protonic Conductors

    DEFF Research Database (Denmark)

    Muccillo, R.; Esposito, Vincenzo; de Florio, D. Z.

    2017-01-01

    Gadolinium, yttrium and samarium-doped barium cerate pressed pellets were submitted to flash sintering experiments isothermally in the temperature range 800-1300oC under 200 V cm-1 electric field. The pellets were positioned inside a dilatometer furnace with Pt-Ir electrodes connected either...... to a power supply or to an impedance analyzer to evaluate the bulk and the grain boundary contributions to the electrical resistivity. Near full density was achieved in the sintered samples. The combined results of dilatometry and impedance measurements in conventionally and flash sintered specimens show...... substantial improvement of the electrical conductivity. Joule heating is assumed to be the primary effect for sintering. Improved grain-to-grain contact and the removal of depleted chemical species due to Joule heating at the space charge region are proposed, respectively, as the reasons for the decrease...

  11. Fuel pellet loading apparatus

    International Nuclear Information System (INIS)

    1980-01-01

    Apparatus is described for loading a predetermined amount of nuclear fuel pellets into nuclear fuel elements and particularly for the automatic loading of fuel pellets from within a sealed compartment. (author)

  12. The US pellet market

    International Nuclear Information System (INIS)

    Elliot, S.

    2007-01-01

    Bear Mountain is the largest producer of pellets, firelogs, animal beddings, and barbecue pellets in Western United States. The company's branded products are sold directly to more than 400 retail dealers. This presentation included a series of graphs depicting Bear Mountain's USA pellet sales in tons from 2002 to 2007; truckloads to various distribution areas; pellet stoves and insert units shipped from 1998 to 2006; and hearth appliance shipments from 1998 to 2006. It was noted that in the United States, 98 per cent of the pellets sold come in 40 pound bags and are delivered to retailers by truck. Space is needed for inventory purposes, as each customer may use 2 to 4 tons. The pellets are used in small ash capacity room heaters. The pellet producers buy sawdust from area mills. It was noted that the soft housing market combined with competition for pulp and paper has pinched the supply of pellets. Pellets were in short supply in the west coast during the winter of 2006-2007 and in eastern United States during the winters of 2004-2005 and 2005-2006, indicating that summer production of pellets is required in order to meet winter demand. The key demand factors for pellets include stove sales; pellet pricing; pricing of other fuels; and, weather. The key supply factors for pellets include availability of sawdust; logistics; competition; and cost. The greatest challenge facing pellet producers is the high cost of freight. It was concluded that 2008 will be another year of uncertainty for pellet producers, due to the abundant supply of pellets in the east and midwest, and stabilized alternative fuel pricing. tabs., figs

  13. Foaming Glass Using High Pressure Sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... variations. One way is by saturation of glass melts with gas. The other involves sintering of powdered glass under a high gas pressure resulting in glass pellets with high pressure bubbles entrapped. Reheating the glass pellets above the glass transition temperature under ambient pressure allows the bubbles...... to expand. After heat-treatment foam glass can be obtained with porosities of 80–90 %. In this study we conduct physical foaming of cathode ray tube (CRT) panel glass by sintering under high pressure (5-25 MPa) using helium, nitrogen, or argon at 640 °C (~108 Pa s). Reheating a sample in a heating...

  14. Wood pellet research program

    International Nuclear Information System (INIS)

    Sohkansanj, S.; Bi, T.

    2006-01-01

    Wood pellets are composed of waste wood materials such as sawmill residue, municipal landfill waste and grain crops. Due to the high temperature combustion used to form the waste materials into the pellet, no additives or glues are necessary to bind them. The pellets are typically used for home heating; heat and power production; poultry bedding; and in biorefineries. This presentation provided an outline of the University of British Columbia wood pellet research and development program. Research at the university is being conducted to develop new types of pellets. Researchers at the program also analyze the physical and chemical properties of pellets in order to optimize pellet density and heating values. Wood pellet modelling and simulation studies are carried out, and various training and education programs are also offered. Research is currently being conducted to develop a reactor for off-gassing experiments. This presentation also provided details of a study investigating the economics of wood pellet production and transport. Pellet production costs and feedstock costs were compared. A summary of the costs and energy inputs of pellet production included details of product storage; transportation and transfer; handling; and transportation to energy plants. It was concluded that more than 35 per cent of the energy content of biomass is used up in the processing and transport of Canadian wood pellets to Europe. refs., tabs., figs

  15. Technological aspects of UO2 sintering at low temperature

    International Nuclear Information System (INIS)

    Thern, Gerardo G.; Dominguez, Carlos A.; Benitez, Ana M.; Marajofsky, Adolfo

    1999-01-01

    Within the Fuel Cycle Program of CNEA, the knowledge that plant personnel has on sintering at low temperature was evaluated, because this process could decrease costs for UO 2 and (U,Gd)O 2 pellets production, simplify the furnace maintenance and facilitate the automation of the production process, specially convenient for uranium recovery. By applying this technology, some companies have achieved production at pilot-scale and irradiated a significant number of pellets. (author)

  16. Compaction of AWBA fuel pellets without binders (AWBA Development Program)

    International Nuclear Information System (INIS)

    Johnson, R.G.R.

    1982-08-01

    Highly active oxide fuel powders, composed of UO 2 , UO 2 -ThO 2 , or ThO 2 , were compacted into ultra-high density pellets without the use of binders. The objective of the study was to select the optimum die lubricant for compacting these powders into pellets in preparation for sintering to densities in excess of 97% Theoretical Density. The results showed that sintered density was a function of both the lubricant bulk density and concentration with the lowest bulk density lubricant giving the highest sintered densities with a lubricant concentration of 0.1 weight percent. Five calcium and zinc stearates were evaluated with a calcium stearate with a 15 lb/ft 3 bulk density being the best lubricant

  17. Fabrication of ceramic fuel pellets for isotopic heat sources

    International Nuclear Information System (INIS)

    Rankin, D.T.; Congdon, J.W.; Duncan, N.D.; Livingston, J.T.

    1982-01-01

    A production process was developed to fabricate cylindrical pellets for the GPHS. The process consists of hot-pressing a blended mixture of sintered 238 PuO 2 granules prepared from calcined plutonium oxalate powder. The product is a pellet of nominally 84.5% total density which generates 62.5 watts (thermal). Hot pressing and granule sintering conditions require close control to minimize surface and internal cracking and to permit ejection of the pellet from the hot press die. Uniform density and distribution of large intergranule porosity in the microstructure appear to contribute to the dimensional stability required at elevated temperatures and the mechanical ruggedness required for routine handling during production operations

  18. Injection of Deuterium Pellets

    DEFF Research Database (Denmark)

    Sørensen, H.; Andersen, P.; Andersen, S. A.

    1984-01-01

    A pellet injection system made for the TFR tokamak at Fontenay-aux-Roses, Paris is described. 0.12-mg pellets are injected with velocities of around 600-700 m/s through a 5-m long guide tube. Some details of a new light gas gun are given; with this gun, hydrogen pellets are accelerated...... to velocities above 1400 m/s, deuterium pellets to velocities above 1300 m/s and neon pellets to velocities above 500 m/s. Finally, a new acceleration method where a pellet should be accelerated by means of a magnetically stabilised electrical discharge is discussed, and a set up for measuring of the pellet...

  19. Effect of sintering process parameters on the properties of 3Y-PSZ ceramics

    International Nuclear Information System (INIS)

    Chu, H L; Chen, R S; Wang, C L; Hwang, W S; Lee, H E; Sie, Y Y; Wang, M C

    2013-01-01

    The effect of sintering process parameters on the properties of 3 mol% yttria partially stability zirconia (3Y-PSZ) ceramics has been investigated. The relative density of the sintered pellet rapidly increases from 70.5 to 93.6% with rose temperature from 1473 to 1573 K. In addition, the relative density only slightly increases from 94.9 to 96.6 %, when rose sintered temperature from 1573 to 1773 K. This result shows that no significant influence on the densification behavior when sintering at 1573 to 1773 K for 2 h. The Vickers hardness and toughness also increase with the sintered temperature

  20. Microwave synthesis and sintering characteristics of CaCu3 Ti4

    Indian Academy of Sciences (India)

    WINTEC

    Archimedes principle using xylene as the liquid medium. Scanning electron microscope (SEM) (Cambridge Stereo- scan S-360) was employed to study the microstructure of the sintered pellets. The capacitance measurements of the electroded pellets were carried out as a function of fre- quency (100 Hz–1 MHz) using an ...

  1. Sintering and densification; new techniques: sinter forging

    International Nuclear Information System (INIS)

    Winnubst, A.J.A.

    1998-01-01

    In this chapter pressure assisted sintering methods will be described. Attention will mainly be paid to sinter forging as a die-wall free uniaxial pressure sintering technique, where large creep strains are possible. Sinter forging is an effective tool to reduce sintering temperature and time and to obtain a nearly theoretically dense ceramic. In this way grain size in tetragonal zirconia ceramics can be reduced down to 100 nm. Another important phenomenon is the reduction of the number density and size of cracks and flaws resulting in higher strength and improved reliability, which is of utmost importance for engineering ceramics. The creep deformation during sinter forging causes a rearrangement of the grains resulting in a reduction of interatomic spaces between grains, while grain boundary (glassy) phases can be removed. The toughness and in some cases the wear resistance is enhanced after sinter forging as a result of the grain-boundary-morphology improvement. (orig.)

  2. Advanced doped UO2 pellets in LWR applications

    International Nuclear Information System (INIS)

    Arborelius, Jakob; Backman, Karin; Hallstadius, Lars

    2006-01-01

    The nuclear industry strives to reduce the fuel cycle cost, enhance flexibility and improve the reliability of operation. This can be done by both increasing the fuel weight and optimizing rod internal properties that affect operational margins. Further, there is focus on reducing the consequences of fuel failures. To meet these demands Westinghouse has developed ADOPT (Advanced Doped Pellet Technology) UO 2 fuel containing additions of chromium and aluminium oxides. This paper presents results from the extensive investigation program which covered examinations of doped and reference standard pellets both in the manufactured and irradiated states. The additives facilitate pellet densification during sintering and enlarge the pellet grain size. The final manufactured doped pellets reach about 0.5% higher density within a shorter sintering time and a five fold larger grain size compared with standard UO 2 fuel pellets. The physical properties of the pellets, including heat capacity, thermal expansion coefficient, melting temperature, thermal diffusivity, have been investigated and differences between the doped and standard UO 2 pellets are small. The in-reactor performance of the ADOPT pellets has been investigated in pool-side and hotcell Post Irradiation Examinations (PIEs), as well as in the Studsvik R2 test reactor. The investigations have identified three areas of improved operational behaviour: Reduced fission gas release, improved PCI performance thanks to increased pellet plasticity and higher resistance against post-failure degradation. Fuel segments have been exposed to ramp tests and enhanced power steady-state operation in the Studsvik R2 reactor after base-irradiation to above 30MWd/kgU in a commercial BWR. ADOPT reveals up to 50% lower fission gas release than standard UO 2 pellets. The fuel degradation behaviour has been studied in two oxidizing tests, a thermal-microbalance test and an erosion test under irradiation. The tests show that ADOPT pellets

  3. Fabrication of nano-structured UO2 fuel pellets

    International Nuclear Information System (INIS)

    Yang, Jae Ho; Kang, Ki Won; Rhee, Young Woo; Kim, Dong Joo; Kim, Jong Heon; Kim, Keon Sik; Song, Kun Woo

    2007-01-01

    Nano-structured materials have received much attention for their possibility for various functional materials. Ceramics with a nano-structured grain have some special properties such as super plasticity and a low sintering temperature. To reduce the fuel cycle costs and the total mass of spent LWR fuels, it is necessary to extend the fuel discharged burn-up. In order to increase the fuel burn-up, it is important to understand the fuel property of a highly irradiated fuel pellet. Especially, research has focused on the formation of a porous and small grained microstructure in the rim area of the fuel, called High Burn-up Structure (HBS). The average grain size of HBS is about 300nm. This paper deals with the feasibility study on the fabrication of nano-structured UO 2 pellets. The nano sized UO 2 particles are prepared by a combined process of a oxidation-reducing and a mechanical milling of UO 2 powder. Nano-structured UO 2 pellets (∼300nm) with a density of ∼93%TD can be obtained by sintering nano-sized UO 2 compacts. The SEM study reveals that the microstructure of the fabricated nano-structure UO 2 pellet is similar to that of HBS. Therefore, this bulk nano-structured UO 2 pellet can be used as a reference pellet for a measurement of the physical properties of HBS

  4. New insights into the pelletization mechanism by extrusion/spheronization.

    Science.gov (United States)

    Koester, Martin; Thommes, Markus

    2010-12-01

    Pellet manufacturing by extrusion/spheronization is quite common in the pharmaceutical field because the obtained product is characterized by a high sphericity as well as a narrow particle size distribution. The established mechanisms only consider deformation of the initially fractured particles but do not account for mass transfer between the particles as a factor in achieving spherical particles. This study dealt with the visualization of mass transfer during spheronization. Therefore, two common pelletization aids, microcrystalline cellulose and kappa-carrageenan, were used alone as well as in combination with lactose as a filler. This study proves that mass transfer between particles must be considered in addition to plastic deformation in order to capture the spheronization mechanism. Moreover, it is evident that there are regional distinctions in the amount of mass transfer at the particle surface. Therefore, the commonly espoused pelletization mechanisms need to be extended to account for material transfer between pellet particles, which has not been considered before.

  5. Absolutely uniform illumination of laser fusion pellets

    International Nuclear Information System (INIS)

    Schmitt, A.J.

    1984-01-01

    Absolutely uniform illumination of spherical laser fusion pellets is possible when the energy deposition from a single beam is given by a simple cos 2 theta distribution. Conditions can be derived for which the laser beam targeting angles allow this absolute illumination uniformity. Configurations based upon the cube and higher order Platonic solids satisfy the constraints, as well as an infinite class of other less symmetric configurations

  6. Absolutely uniform illumination of laser fusion pellets

    International Nuclear Information System (INIS)

    Schmitt, A.J.

    1984-01-01

    Absolutely uniform illumination of spherical laser fusion pellets is possible when the energy deposition from a single laser beam is given by a simple cos 2 theta distribution. Conditions can be derived for which the laser beam targeting angles allow this absolute illumination uniformity. Configurations based upon the cube and higher order Platonic solids satisfy the constraints, as well as infinite class of other less symmetric configurations

  7. Processing of Syndiotactic Polystyrene to Microspheres for Part Manufacturing through Selective Laser Sintering

    Directory of Open Access Journals (Sweden)

    Nicolas Mys

    2016-10-01

    Full Text Available Syndiotactic polystyrene pellets were processed into powder form using mechanical (ball milling, rotor milling and physicochemical (spray drying techniques with the intention of using it as feed material for selective laser sintering. New materials are an important component in broadening the application window for selective laser sintering but must meet strict requirements to be used. Particles obtained were characterized in size and shape using SEM imaging, analyzed by software, and compared to the product obtained by conventional ball milling. Rotor milling and spray drying proved capable of making spherical powders, yet only rotor milling achieved particles with a mean diameter within the desired range of 45–97 µm. Subsequently, the obtained powders were examined for the effect each processing technique imparts on the intrinsic properties of the material. Differential scanning calorimetry analysis revealed amorphization for all methods and a reduction in crystallinity after processing, however, the reduction in crystallinity was acceptably low for the spray-dried and rotor-milled powders. Ball milling displayed an exceptional reduction in crystallinity, suggesting severe degradation. As a final test, the rotor-milled powder was subjected to single-layer test and displayed good coalescence and smooth morphology, albeit with a large amount of warpage.

  8. Tritium pellet injector results

    International Nuclear Information System (INIS)

    Fisher, P.W.; Bauer, M.L.; Baylor, L.R.; Deleanu, L.E.; Fehling, D.T.; Milora, S.L.; Whitson, J.C.

    1988-01-01

    Injection of solid tritium pellets is considered to be the most promising way of fueling fusion reactors. The Tritium Proof-of- Principle (TPOP) experiment has demonstrated the feasibility of forming and accelerating tritium pellets. This injector is based on the pneumatic pipe-gun concept, in which pellets are formed in situ in the barrel and accelerated with high-pressure gas. This injector is ideal for tritium service because there are no moving parts inside the gun and because no excess tritium is required in the pellet production process. Removal of 3 He from tritium to prevent blocking of the cryopumping action by the noncondensible gas has been demonstrated with a cryogenic separator. Pellet velocities of 1280 m/s have been achieved for 4-mm-diam by 4-mm-long cylindrical tritium pellets with hydrogen propellant at 6.96 MPa (1000 psi). 10 refs., 10 figs

  9. Development of Impregnated Agglomerate Pelletization (IAP) process for fabrication of (Th,U)O 2 mixed oxide pellets

    Science.gov (United States)

    Khot, P. M.; Nehete, Y. G.; Fulzele, A. K.; Baghra, Chetan; Mishra, A. K.; Afzal, Mohd.; Panakkal, J. P.; Kamath, H. S.

    2012-01-01

    Impregnated Agglomerate Pelletization (IAP) technique has been developed at Advanced Fuel Fabrication Facility (AFFF), BARC, Tarapur, for manufacturing (Th, 233U)O 2 mixed oxide fuel pellets, which are remotely fabricated in hot cell or shielded glove box facilities to reduce man-rem problem associated with 232U daughter radionuclides. This technique is being investigated to fabricate the fuel for Indian Advanced Heavy Water Reactor (AHWR). In the IAP process, ThO 2 is converted to free flowing spheroids by powder extrusion route in an unshielded facility which are then coated with uranyl nitrate solution in a shielded facility. The dried coated agglomerate is finally compacted and then sintered in oxidizing/reducing atmosphere to obtain high density (Th,U)O 2 pellets. In this study, fabrication of (Th,U)O 2 mixed oxide pellets containing 3-5 wt.% UO 2 was carried out by IAP process. The pellets obtained were characterized using optical microscopy, XRD and alpha autoradiography. The results obtained were compared with the results for the pellets fabricated by other routes such as Coated Agglomerate Pelletization (CAP) and Powder Oxide Pelletization (POP) route.

  10. Simulation of Reforming Reactor Tube: Quantifying Catalyst Pellet's Effectiveness Factor

    OpenAIRE

    Da Cruz, Flavio Eduardo

    2016-01-01

    In this work, a consistent mathematical model to simulate a spherical catalytic pellet and a Packed-Bed Reactor (PBR) is develop. The Dusty Gas Model (DGM) is applied to the calculation of the diffusive fluxes in the porous media. Simulations are executed considering hydrogen production from steam methane reforming. Species’ diffusivities are calculated using data from literature as well as the values for tortuosity and porosity. The pellet simulation is performed considering mass, species, m...

  11. Spherical models

    CERN Document Server

    Wenninger, Magnus J

    2012-01-01

    Well-illustrated, practical approach to creating star-faced spherical forms that can serve as basic structures for geodesic domes. Complete instructions for making models from circular bands of paper with just a ruler and compass. Discusses tessellation, or tiling, and how to make spherical models of the semiregular solids and concludes with a discussion of the relationship of polyhedra to geodesic domes and directions for building models of domes. "". . . very pleasant reading."" - Science. 1979 edition.

  12. Spherical CNNs

    OpenAIRE

    Cohen, Taco S.; Geiger, Mario; Koehler, Jonas; Welling, Max

    2018-01-01

    Convolutional Neural Networks (CNNs) have become the method of choice for learning problems involving 2D planar images. However, a number of problems of recent interest have created a demand for models that can analyze spherical images. Examples include omnidirectional vision for drones, robots, and autonomous cars, molecular regression problems, and global weather and climate modelling. A naive application of convolutional networks to a planar projection of the spherical signal is destined t...

  13. Microbeam analysis of hydrogen in coked catalyst pellets

    International Nuclear Information System (INIS)

    Sofield, C.J.; Bridwell, L.B.; Wright, C.J.

    1981-01-01

    The hydrogen content of catalyst pellets has recently been shown to be important in predicting the maximum temperature rise of the catalyst during regeneration in industrial plant. This is because carbonaceous coke deposits (CHsub(0.4) to CHsub(2.0)) accumulate in the pellet during use, which then have to be removed by exothermic oxidation. It is important, in this well established industrial process, to limit the maximum temperature that the catalyst reaches to level s sufficiently low to prevent permanent deactivation by sintering. In view of the importance of the H content as a function of the distance from the surface of the catalyst pellets in predicting maximum temperature rises during de-coking, we have adopted the technique of elastic recoil analysis for use with the Harwell microbeam to obtain measurements of the hydrogen concentration at varying positions along a pellet diameter. The method of analysis is described and illustrated with typical data. (orig.)

  14. Microbeam analysis of hydrogen in coked catalyst pellets

    Science.gov (United States)

    Sofield, C. J.; Bridwell, L. B.; Wright, C. J.

    1981-12-01

    The hydrogen content of catalyst pellets has recently been shown to be important in predicting the maximum temperature rise of the catalyst during regeneration in industrial plant. This is because carbonaceous coke deposits (CH 0.4 to CH 2.0) accumulate in the pellet during use, which then have to be removed by exothermic oxidation. It is important, in this well established industrial process, to limit the maximum temperature that the catalyst reaches to level s sufficiently low to prevent permanent deactivation by sintering. In view of the importance of the H content as a function of the distance from the surface of the catalyst pellets in predicting maximum temperature rises during de-coking, we have adopted the technique of elastic recoil analysis for use with the Harwell microbeam to obtain measurements of the hydrogen concentration at varying positions along a pellet diameter. The method of analysis is described and illustrated with typical data.

  15. Developing and testing a vertical sintering furnace for remote nuclear applications

    International Nuclear Information System (INIS)

    Nesbitt, J.F.; Ryer, C.M.

    1980-01-01

    Horizontal-type furnaces used to sinter fuel pellets on a production basis are large and thus impractical for remote applications. However, research has shown that vertical-type furnaces are adaptable for use and are cheaper to operate and maintain. In 1979, Pacific Northwest Laboratory, working under the auspices of the Department of Energy's Fuel Refabrication and Development (FRAD) Program, began developing an advanced concept for a remotely operated furnace designed specifically to sinter nuclear fuel pellets. The FRAD Program at PNL ended before the sintering of nuclear fuels could be completely verified. However during 1979, PNL performed a sufficient number and variety of tests to establish that nuclear fuel pellets can be sintered in a vertical furnace

  16. Pellet inspection apparatus

    Science.gov (United States)

    Wilks, Robert S.; Taleff, Alexander; Sturges, Jr., Robert H.

    1982-01-01

    Apparatus for inspecting nuclear fuel pellets in a sealed container for diameter, flaws, length and weight. The apparatus includes, in an array, a pellet pick-up station, four pellet inspection stations and a pellet sorting station. The pellets are delivered one at a time to the pick-up station by a vibrating bowl through a vibrating linear conveyor. Grippers each associated with a successive pair of the stations are reciprocable together to pick up a pellet at the upstream station of each pair and to deposit the pellet at the corresponding downstream station. The gripper jaws are opened selectively depending on the state of the pellets at the stations and the particular cycle in which the apparatus is operating. Inspection for diameter, flaws and length is effected in each case by a laser beam projected on the pellets by a precise optical system while each pellet is rotated by rollers. Each laser and its optical system are mounted in a container which is free standing on a precise surface and is provided with locating buttons which engage locating holes in the surface so that each laser and its optical system is precisely set. The roller stands are likewise free standing and are similarly precisely positioned. The diameter optical system projects a thin beam of light which scans across the top of each pellet and is projected on a diode array. The fl GOVERNMENT CONTRACT CLAUSE The invention herein described was made in the course of or under a contract or subcontract thereunder with the Department of Energy bearing No. EY-67-14-C-2170.

  17. An investigation in InGaO3(ZnO)m pellets as cause of variability in ...

    Indian Academy of Sciences (India)

    An investigation in InGaO3(ZnO)m pellets as cause of variability in thin film transistor characteristics. SONACHAND ADHIKARI†, RAJEEV GUPTA†,††, ASHISH GARG††† ..... and aids in the final phase formation. 3.3 Applicability of sintering process for various compositions. After optimizing to two-stage sintering process at.

  18. Electric Field-Assisted Pressureless Sintering of Ceramic Protonic Conductors

    DEFF Research Database (Denmark)

    Muccillo, R.; Esposito, Vincenzo; Zanetti De Florio, Daniel

    2017-01-01

    -5 A the electric current pulse amplitude. The sintering experiments were carried out in ambient atmosphere with the pellets positioned inside a vertical dilatometer furnace with Pt-Ir electrodes connected either to a power supply for applying the electric field or to an impedance analyzer for collecting [-Z''(ω) x......Gadolinium, yttrium and samarium-doped barium cerate (BCGd, BCY and BCSm, respectively) polycrystalline green pellets were submitted to electric field-assisted pressureless sintering experiments isothermally in the temperature range 800-1200oC under 100-200 V cm-1 electric fields, limiting to 1...... of the electrical conductivity of flash sintered specimens. Joule heating is assumed to be the primary effect of the electric current pulse through the specimens. Improved grain-to-grain contact and the removal of depleted chemical species due to Joule heating at the space charge region are proposed, respectively...

  19. Determination Of Simulated Pellet To Pellet Gap Using Neutron Radiography

    International Nuclear Information System (INIS)

    Kusnowo, A.

    1996-01-01

    The defect on the irradiated fuel element could be detected using neutron radiography. The defect could occurred in pellet to pellet gap, cladding, or even cladding to pellet gap. An investigations has been performed to detect pellet to pellet gap defect that might occur in an irradiated fuel element. An Al foil of 0,1; 0,2; 0,3; und 0,4 mm was inserted between pellets to simulate various pellet to pellet gap. The neutron radiography used had power of 700 kW. The result showed that this simulation represented well enough problems that irradiated fuel element may experience

  20. Review of pellet fueling

    International Nuclear Information System (INIS)

    Turnbull, R.J.

    1978-01-01

    Fusion reactors based on the Tokamak concept (possibly mirrors, too) will require a low energy method of fueling. Refueling by using solid pellets of hydrogen isotopes appears to be the most promising low energy technique. The main issue in assessing the feasibility of pellet fueling is the ability of the pellet to penetrate into the central region of the reactor. A review is presented of the various theories predicting the lifetime of the pellet and their regions of applicability. Among the phenomena considered are neutral ablation of the solid, ionized ablation of the solid, shielding of the pellet by neutral molecules and electrons and ions, flow of the ablation cloud, distortion of the magnetic field by the flow of an ionized ablation cloud, and charging and electrostatic shielding of the pellet. A brief summary of results of experiments done by the University of Illinois-Oak Ridge and Riso groups is presented. The results of these experiments indicate that, at least at the low temperatures and densities used, a neutral ablation-neutral shielding model is correct. Finally, since all indications are that in order for pellet fueling to be successful, high velocity pellets will be needed, a brief discussion of possible acceleration techniques is presented

  1. Melting and Sintering of Ashes

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug

    1997-01-01

    , the biggest deviations being found for salt rich (i.e. straw derived) ashes.A simple model assuming proportionality between fly ash fusion and deposit formation was found to be capable of ranking deposition rates for the different straw derived fly ashes, whereas for the fly ashes from coal/straw co......-firing, the model only had a qualitative agreement with the measured ash deposit formation rates.Sintering measurements were carried out by means of compression strength testing of ash pellets. This method showed to not be applicable for the salt rich fly ash derived from straw combustion. For the fly ashes...... have been employed in a simple model for prediction of ash deposit formation, the results of which have been compared to ash deposition formation rates measured at the respective boilers.The ash fusion results were found to directly reflect the ash compositional data:a) Fly ashes and deposits from...

  2. Quantitative image analysis:a focus on automated characterization of structures in optical microscopy of iron ore pellets

    OpenAIRE

    Nellros, Frida

    2013-01-01

    Sintering occurs in many types of material such as iron, ceramics and snow, typically during thermal treatment, and aects the material properties, particularly the strength, by the bonding of particles into a coherent structure. In order to improve the mechanical strength in magnetite iron ore pellets it is important to be able to characterize and quantitatively measure the degree of sintering and features that impact the process of sintering.The aim for this licentiate thesis has been to cre...

  3. Process for the fabrication of nuclear fuel oxide pellets

    International Nuclear Information System (INIS)

    Francois, Bernard; Paradis, Yves.

    1977-01-01

    Process for the fabrication of nuclear fuel oxide pellets of the type for which particles charged with an organic binder -selected from the group that includes polyvinyl alcohol, carboxymethyl cellulose, polyvinyl compounds and methyl cellulose- are prepared from a powder of such an oxide, for instance uranium dioxide. These particles are then compressed into pellets which are then sintered. Under this process the binder charged particles are prepared by stirring the powder with a gas, spraying on to the stirred powder a solution or a suspension in a liquid of this organic binder in order to obtain these particles and then drying the particles so obtained with this gas [fr

  4. Effect of Granule Size on Diametric Tolerance of Annular Fuel Pellet

    International Nuclear Information System (INIS)

    Rhee, Young Woo; Kim, Dong Joo; Kim, Jong Hun; Yang, Jae Ho; Kim, Keon Sik; Kang, Ki Won; Song, Kun Woo

    2008-01-01

    A dual cooled annular fuel has been seriously considered as a favorable option for an extended power uprate of a Pressurized Water Reactor fuel assembly. An annular fuel shows a lot of advantages from the point of a fuel safety and its economy due to its unique configurational merit such as an increased heat transfer area and a thin pellet thickness. From the viewpoint of the fuel pellet fabrication, however, the unique shape of annular fuel pellet causes challenging difficulties to satisfy a diametric tolerance. A sintered cylindrical PWR fuel pellet fabricated by a conventional double-acting press has an hour-glass shape due to an inhomogeneous green density distribution in a powder compact. Thus, a sintered pellet usually undergoes a centerless grinding process in order to secure diametric tolerance specifications. In the case of an annular pellet fabrication using a conventional double-acting press, the same hour-glass shape would probably occur. An inhomogeneous green density distribution in a powder compact is attributed to granule-granule frictions and granule to pressing mold wall frictions. Frictions result in an irregular pressing load distribution in a powder compact. In order to mitigate the frictions, a lot of process variables should be considered such as pre-compaction pressure, lubricant content, granule size and compaction pressure. The purpose of this study is to investigate the effect of a granule size on the amount of deformation after sintering, in other words, the amount of an hour-glassing. The granules with classified size ranges were made to green annular pellets with the same height and diameters. The hour-glassing amounts of the sintered annular pellets were measured and compared with that of the annular pellet made by unclassified granule

  5. Low density, variation in sintered density and high nitrogen in uranium dioxide

    International Nuclear Information System (INIS)

    Balakrishna, Palanki; Murty, B.N.; Anuradha, M.; Nageshwara Rao, P.; Jayaraj, R.N.; Ganguly, C.

    2000-01-01

    Low sintered density and density variation in sintered UO 2 were found to have been caused by non uniformity in the granule feed characteristics to the compacting press. The nitrogen impurity content of sintered UO 2 was found to be sintering furnace related and associated with low sintered density pellets. The problems of low density, variation in sintered density and high nitrogen could be solved by the replacement of the prevailing four punch precompaction by a single punch process; by the introduction of a vibro-sieve for the separation of fine particles from the press feed granules; by innovation in the powder feed shoe design for simultaneous and uniform dispensing of powder in all the die holes; by increasing the final compaction pressure and by modifying the gas flows and preheat temperature in the sintering furnace. (author)

  6. Synthesis, Sintering, and Electrical Properties of BaCe0.9−xZrxY0.1O3−δ

    DEFF Research Database (Denmark)

    Ricote, S.; Caboche, G.; Estournes, C.

    2008-01-01

    BaCe0.9-xZrxY0.1O3-delta powders were synthesized by a solid-state reaction. Different contents of cerium and zirconium were studied. Pellets were sintered using either conventional sintering in air at 1700 degrees C or the Spark Plasma Sintering (SPS) technique. The density of the samples sinter......, and reproduction in any medium, provided the original work is properly cited....

  7. Pellet plant energy simulator

    Science.gov (United States)

    Bordeasu, D.; Vasquez Pulido, T.; Nielsen, C.

    2016-02-01

    The Pellet Plant energy simulator is a software based on advanced algorithms which has the main purpose to see the response of a pellet plant regarding certain location conditions. It combines energy provided by a combined heat and power, and/or by a combustion chamber with the energy consumption of the pellet factory and information regarding weather conditions in order to predict the biomass consumption of the pellet factory together with the combined heat and power, and/or with the biomass consumption of the combustion chamber. The user of the software will not only be able to plan smart the biomass acquisition and estimate its cost, but also to plan smart the preventive maintenance (charcoal cleaning in case of a gasification plant) and use the pellet plant at the maximum output regarding weather conditions and biomass moisture. The software can also be used in order to execute a more precise feasibility study for a pellet plant in a certain location. The paper outlines the algorithm that supports the Pellet Plant Energy Simulator idea and presents preliminary tests results that supports the discussion and implementation of the system

  8. MULTIPLE UNIT DOSAGE FORM - PELLET AND PELLETIZATION TECHNIQUES: AN OVERVIEW

    OpenAIRE

    Kumar Vikash; Mishra Santosh Kumar; Lather Amit; Vikas; Singh Ranjit

    2011-01-01

    Pellets have been used in the pharmaceutical industry for more than four decades, with the advent of controlled release technology, that the full impact of the inherent advantages of pellets over single unit dosage forms have been realized, not only has focused on refining and optimizing existing pelletization techniques, but also focused on the development of novel approaches and procedures for manufacturing of pellets. The present review outlines the manufacturing and evaluation of pellets....

  9. Onset conditions for flash sintering of UO2

    Science.gov (United States)

    Raftery, Alicia M.; Pereira da Silva, João Gustavo; Byler, Darrin D.; Andersson, David A.; Uberuaga, Blas P.; Stanek, Christopher R.; McClellan, Kenneth J.

    2017-09-01

    In this work, flash sintering was demonstrated on stoichiometric and non-stoichiometric uranium dioxide pellets at temperatures ranging from room temperature (26 °C) up to 600 °C . The onset conditions for flash sintering were determined for three stoichiometries (UO2.00, UO2.08, and UO2.16) and analyzed against an established thermal runaway model. The presence of excess oxygen was found to enhance the flash sintering onset behavior of uranium dioxide, lowering the field required to flash and shortening the time required for a flash to occur. The results from this study highlight the effect of stoichiometry on the flash sintering behavior of uranium dioxide and will serve as the foundation for future studies on this material.

  10. Grain growth in thoria and thoria-base fuel pellets (LWBR development program)

    Energy Technology Data Exchange (ETDEWEB)

    Smid, R.J.

    1976-01-01

    The kinetics of grain growth in ThO/sub 2/-base sintered compacts were investigated to determine the cause of a nonuniform microstructural cross section. It was concluded that trace impurities which inhibit continuous grain growth at the pellet interior were removed by vaporization at the pellet exterior. This resulted in relatively normal grain growth at the pellet surface and discontinuous grain growth at the pellet interior. Calcining the starting ThO/sub 2/ powder to a slightly higher temperature removed inhibiting impurities but also decreased the driving force for grain growth by reducing the surface area of the powder. Mixing high and low temperature calcined ThO/sub 2/ resulted in improved grain growth. Increased oxygen partial pressure and temperature during sintering increased grain boundary mobility in spite of the inhibiting impurity. The specific inhibiting impurity was not isolated during this investigation.

  11. Grain growth in thoria and thoria-base fuel pellets (LWBR development program)

    International Nuclear Information System (INIS)

    Smid, R.J.

    1976-01-01

    The kinetics of grain growth in ThO 2 -base sintered compacts were investigated to determine the cause of a nonuniform microstructural cross section. It was concluded that trace impurities which inhibit continuous grain growth at the pellet interior were removed by vaporization at the pellet exterior. This resulted in relatively normal grain growth at the pellet surface and discontinuous grain growth at the pellet interior. Calcining the starting ThO 2 powder to a slightly higher temperature removed inhibiting impurities but also decreased the driving force for grain growth by reducing the surface area of the powder. Mixing high and low temperature calcined ThO 2 resulted in improved grain growth. Increased oxygen partial pressure and temperature during sintering increased grain boundary mobility in spite of the inhibiting impurity. The specific inhibiting impurity was not isolated during this investigation

  12. Mobile Biomass Pelletizing System

    Energy Technology Data Exchange (ETDEWEB)

    Thomas Mason

    2009-04-16

    This grant project examines multiple aspects of the pelletizing process to determine the feasibility of pelletizing biomass using a mobile form factor system. These aspects are: the automatic adjustment of the die height in a rotary-style pellet mill, the construction of the die head to allow the use of ceramic materials for extreme wear, integrating a heat exchanger network into the entire process from drying to cooling, the use of superheated steam for adjusting the moisture content to optimum, the economics of using diesel power to operate the system; a break-even analysis of estimated fixed operating costs vs. tons per hour capacity. Initial development work has created a viable mechanical model. The overall analysis of this model suggests that pelletizing can be economically done using a mobile platform.

  13. Validation of an image analysis method for estimating coating thickness on pellets

    DEFF Research Database (Denmark)

    Larsen, C.C.; Sonnergaard, Jørn; Bertelsen, P.

    2003-01-01

    A digital image analysis method for the estimation of mean pellet size and coating thickness employing optical microscopy was evaluated. The coating thickness was expressed as the difference in mean projected area radius of the uncoated and the coated pellets. The repeatability, the intermediate...... of controlling and monitoring the illumination technique utilised. Calibration of the image analysis equipment was of the highest importance. Using pellets with a high degree of sphericity and narrow size distribution, it was sufficient to use 1000 pellets to estimate the mean pellet size and the coating...... thickness with an accuracy of ±1.2 μm. An equation is presented for an approximation of the number of pellets necessary to achieve a given accuracy in the estimation of mean pellet size and coating thickness....

  14. New fabrication method of UO2-Gd2O3 pellet

    International Nuclear Information System (INIS)

    Yoo, M. J.; Yang, C. M.; Kim, Y. R.; Na, S. H.; Kim, S. Y.; Kim, Y. K.; Lee, S. C.; Lee, Y. W.

    2003-01-01

    UO 2 -8wt%Gd 2 O 3 pellets were fabricated by a new method. Two processes - milling by a continous-type attrition mill and spherodizing- were introduced in the fabrication method. The microstructure of sintered pellet appeared homogenous and showed larger grain size than that of conventional method which generally involves a mechanical mxing. And it appears that both precompacting process and granulating process can be avoided owing to good flow ability of the milled powder with the spherodizing treatment

  15. The Asian Wood Pellet Markets

    Science.gov (United States)

    Joseph A. Roos; Allen Brackley

    2012-01-01

    This study examines the three major wood pellet markets in Asia: China, Japan, and South Korea. In contrast to the United States, where most wood pellets are used for residential heating with pellet stoves, a majority of the wood pellets in Asia are used for co-firing at coal-fired power plants. Our analysis indicated that Japan is the largest importer of wood pellets...

  16. From a single pellet press to a bench scale pellet mill - Pelletizing six different biomass feedstocks

    DEFF Research Database (Denmark)

    Puig Arnavat, Maria; Shang, Lei; Sárossy, Zsuzsa

    2016-01-01

    The increasing demand for biomass pellets requires the investigation of alternative raw materials for pelletizetion. In the present paper, the pelletization process of fescue, alfalfa, sorghum, triticale, miscanthus and willow is studied to determine if results obtained in a single pellet press...... (SPP) can be extrapolated to larger scale pellet mills. The single pellet press was used to find the optimum moisture content and die operating temperature for pellet production. Then, these results were compared with those obtained from a bench-scale pellet mill. A moisture content of around 10 wt...

  17. Remote visual inspection of nuclear fuel pellets with fiber optics and video image processing

    International Nuclear Information System (INIS)

    Moore, F.W.

    1987-01-01

    Westinghouse Hanford Company has designed and constructed a nuclear fuel fabrication process line for the U.S. Department of Energy. This process line includes a system that remotely inspects the cylindrical surface of nuclear fuel pellets for surface spots, flaws, or discoloration. The pellets are inspected on a 100% basis after pellet sintering. A feeder delivers the pellets directly to a fiber optic inspection head, which views one pellet surface at a time and images it to a closed-circuit color television camera (CCTV). The output signal of the CCTV is input to a digital imaging processor that stores approximately 25 pellet images at a time. A human operator visually examines the images of the pellet surfaces on a high resolution monitor and accepts or rejects the pellets based on visual standards. The operator uses a digitizing tablet to record the location of rejected pellets, which are then automatically removed from the product stream. The system is expandable to automated disposition of the pellet surface image

  18. The effect of particle size distributions on the microstructural evolution during sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund

    2013-01-01

    Microstructural evolution and sintering behavior of powder compacts composed of spherical particles with different particle size distributions (PSDs) were simulated using a kinetic Monte Carlo model of solid state sintering. Compacts of monosized particles, normal PSDs with fixed mean particle ra...

  19. Description of pelletizing facility

    Energy Technology Data Exchange (ETDEWEB)

    Vojin Cokorilo; Dinko Knezevic; Vladimir Milisavljevic [University of Belgrade, Belgrade (Serbia). Faculty of Mining and Geology

    2006-07-01

    A lot of electrical energy in Serbia was used for heating, mainly for domestics. As it is the most expensive source for heating the government announced a National Program of Energy Efficiency with only one aim, to reduce the consumption of electric energy for the heating. One of the contributions to mentioned reduction is production of coal pellets from the fine coal and its use for domestic heating but also for heating of schools, hospitals, military barracks etc. Annual production of fine coal in Serbia is 300,000 tons. The stacks of fine coal present difficulties at each deep mine because of environmental pollution, spontaneous combustion, low price, smaller market etc. To overcome the difficulties and to give the contribution to National Program of Energy Efficiency researchers from the Department of Mining Engineering, the University of Belgrade designed and realized the project of fine coal pelletizing. This paper describes technical aspect of this project. Using a CPM machine Model 7900, a laboratory facility, then a semi-industrial pelletizing facility followed by an industrial facility was set up and produced good quality pellets. The plant comprised a coal fines hopper, conveyor belt, hopper for screw conveyor, screw conveyor, continuous mixer conditioner, binder reservoir, pump and pipelines, pellet mill, product conveyor belt and product hopper. 4 refs., 3 figs., 1 tab.

  20. Addition of niobia in alumina and its effects at its sintered microstructure

    International Nuclear Information System (INIS)

    Gomes, L.B.; Lima, M.M.O.; Pereira, A.S.; Bergmann, C.P.

    2016-01-01

    In this work, niobia was used as sintering additive of alumina in concentrations of 0.15, 0.5, 2 and 4 wt%. Homogenized powders was uniaxially pressed (200MPa) forming ceramic pellets with 10 mm diameter. The green bodies were sintered at 1400, 1500 and 1600°C for 60 minutes using a heating rate of 2,5°C.min -1 . After sintering, the specimens were polished using diamond paste with different particle sizes. The specimen's microstructure was analyzed by Scanning Electron Microscopy (SEM) and crystalline phases were determined by X-ray Diffraction (XRD). Results indicate that when niobia and alumina react they form AlNbO4 by liquid phase sintering. This phase is located among alumina grain. It was also verified that niobia addition promotes grain growth, acting as sintering agent, and this effect grows as niobia content and sintering temperature increase. (author)

  1. Production of zinc pellets

    Science.gov (United States)

    Cooper, John F.

    1996-01-01

    Uniform zinc pellets are formed for use in batteries having a stationary or moving slurry zinc particle electrode. The process involves the cathodic deposition of zinc in a finely divided morphology from battery reaction product onto a non-adhering electrode substrate. The mossy zinc is removed from the electrode substrate by the action of gravity, entrainment in a flowing electrolyte, or by mechanical action. The finely divided zinc particles are collected and pressed into pellets by a mechanical device such as an extruder, a roller and chopper, or a punch and die. The pure zinc pellets are returned to the zinc battery in a pumped slurry and have uniform size, density and reactivity. Applications include zinc-air fuel batteries, zinc-ferricyanide storage batteries, and zinc-nickel-oxide secondary batteries.

  2. Nuclear fuel rod with burnable plate and pellet-clad interaction fix

    International Nuclear Information System (INIS)

    Boyle, R.F.

    1987-01-01

    This patent describes a nuclear fuel rod comprising a metallic tubular cladding containing nuclear fuel pellets, the pellets containing enriched uranium-235. The improvement described here comprises: ceramic wafers, each wafter comprising a sintered mixture of gadolinium oxide and uranium dioxide, the uranium oxide having no more uranium-235 than is present in natural uranium dioxide. Each of the wafers is axially disposed between a major portion of adjacent the nuclear fuel pellets, whereby the wafers freeze out volatile fission products produced by the nuclear fuel and prevent interaction of the fission products with the metallic tubing cladding

  3. Pelletizing properties of torrefied spruce

    DEFF Research Database (Denmark)

    Stelte, Wolfgang; Clemons, Craig; Holm, Jens K.

    2011-01-01

    Torrefaction is a thermo-chemical conversion process improving the handling, storage and combustion properties of wood. To save storage space and transportation costs, it can be compressed into fuel pellets of high physical and energetic density. The resulting pellets are relatively resistant......, with hemicelluloses being most sensitive to thermal degradation. The chemical changes had a negative impact, both on the pelletizing process and the pellet properties. Torrefaction resulted in higher friction in the press channel of the pellet press and low compression strength of the pellets. Fracture surface...

  4. Modeling pellet impact drilling process

    Science.gov (United States)

    Kovalyov, A. V.; Ryabchikov, S. Ya; Isaev, Ye D.; Ulyanova, O. S.

    2016-03-01

    The paper describes pellet impact drilling which could be used to increase the drilling speed and the rate of penetration when drilling hard rocks. Pellet impact drilling implies rock destruction by metal pellets with high kinetic energy in the immediate vicinity of the earth formation encountered. The pellets are circulated in the bottom hole by a high velocity fluid jet, which is the principle component of the ejector pellet impact drill bit. The experiments conducted has allowed modeling the process of pellet impact drilling, which creates the scientific and methodological basis for engineering design of drilling operations under different geo-technical conditions.

  5. Optimization of UO{sub 2} Granule Characteristics for UO{sub 2}-Mo Pellet Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjoo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik; Oh, Jang Soo; Yang, Jae Ho; Koo, Yanghyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The in-reactor performance, integrity, safety and accident tolerance of the nuclear fuel can be significantly affected by the thermal conductivity of the UO{sub 2} fuel pellet. The improvement in the thermal conductivity of the UO{sub 2} fuel pellet can enhance the fuel performance in various ways. Typically, the FGR (Fission Gas Release) can be reduced by the application of a large-grain fuel pellet because the moving path of the fission gas to the grain boundary is much longer. In addition, the mobility of the fission gases is reduced by the lower temperature gradient in the UO{sub 2} fuel pellet. That is to say, the capacity of the fission gas retention of the fuel pellet can increase. In addition, the lower centerline temperature of the fuel pellet affects the accident tolerance for nuclear fuel as well as the enhancement of fuel safety and fuel pellet integrity under normal operation conditions. In addition, the nuclear reactor power can be uprated owing to the higher safety margin. Thus, many researches on enhancing the thermal conductivity of a nuclear fuel pellet for LWRs have been performed in various ways. From the viewpoint of the development of fuel pellet fabrication technology, an enhancement of the thermal conductivity of a pellet can be obtained by the addition of a higher thermal conductive material in the UO{sub 2} pellet. It is known that a UO{sub 2}-metal composite pellet is one of the most effective concepts. However, to maximize the effect of the metallic phase for thermal conductivity enhancement, a continuous channel of the metallic phase in the UO{sub 2} matrix must be formed. Additionally, if the fabrication process of a UO{sub 2}-metal composite pellet is compatible with a conventional sintering process, the developed technology will be favorable. To enhance the thermal conductivity of a UO{sub 2} pellet, there are the various methods for an appropriate arrangement of the high thermal conductive material in a UO{sub 2} matrix. In this

  6. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

    ...) technology selective laser sintering (SLS). BME has successfully implemented a pilot facility to fabricate calcium phosphate implants using anatomical data coupled with the selective laser sintering process...

  7. A method for sintering

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides a method for sintering, comprising in the following order the steps of: providing a body in the green state or in the pre-sintered state on a support; providing a load on at least one spacer on the support such that the load is located above said body in the green...

  8. Grate-kiln pelletization of Indian hematite fines and its industrial practice

    Science.gov (United States)

    Zhu, De-qing; Zhang, Feng; Guo, Zheng-qi; Pan, Jian; Yu, Wei

    2017-05-01

    Indian hematite fines normally have a high iron grade and minor impurities; they are usually used as sinter fines for feeding into a blast furnace. In this work, the grindability properties of two kinds of Indian hematite fines and the roasting behaviors and induration characteristics of pellets made from these fines were revealed through experiments involving dry ball milling and small-scale and pilot-scale tests. In addition, the microstructures of the particles of ground India hematite fines and fired pellets were investigated using optical microscopy. On the basis of the results, a grate-kiln production line with an annual output of 1.2 Mt of oxidized pellets was established in India. This pellet plant operates stably and reliably, further confirming that preparing high-quality pellets with Indian hematite fines pretreated by dry ball milling is an industrially feasible process.

  9. Enhanced proton conductivity of yttrium-doped barium zirconate with sinterability in protonic ceramic fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ka-Young; Seo, Yongho; Kim, Ki Buem [HMC & Green Energy Research Institute, Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Song, Sun-Ju [Department of Materials Science and Engineering, Chonnam National University, Gwangju 550-749 (Korea, Republic of); Park, Byoungnam [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of); Park, Jun-Young, E-mail: jyoung@sejong.ac.kr [HMC & Green Energy Research Institute, Department of Nanotechnology and Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of)

    2015-08-05

    Highlights: • Report effects of ceramic processing methods on the electrical conductivity of BZY. • Present effects of sintering aids on the conductivity and density of BZY. • CuO is the most effective sintering aid for the BZY. • Polymer gelation is the most effective method in terms of conductivity of BZY. • Grain boundary conductivity of the polymer gelation BZY is higher than others. - Abstract: In this study, we report the effects of various ceramic processing methods with different sintering aids on the relative density, crystallinity, microstructure, and electrical conductivity of proton conducting BaZr{sub 0.85}Y{sub 0.15}O{sub 3−δ} (BZY) pellets in details. First, the BZY ceramic pellets are fabricated by the solid-state reactive sintering by adding diverse sintering aids including CuO, NiO, ZnO, SnO, MgO, and Al{sub 2}O{sub 3}. Among these, CuO is found to be the most effective sintering aid in terms of the sintering temperature and total conductivity. However, transition metals as sintering aids have detrimental effects on the electrical conductivity of the BZY electrolytes. Second, the BZY electrolytes have been synthesized by four different methods: the solid-state, combustion, hydrothermal, and polymer gelation methods. The BZY pellets synthesized by the polymer gelation method exhibit dense microstructure with a high relative density of 95.3%. Moreover, the electrical conductivity of the BZY pellets synthesized by the polymer gelation method is higher than those prepared by the solid-state methods under the same test conditions: 1.28 × 10{sup −2} S cm{sup −1} (by the polymer gelation method) vs. 0.53 × 10{sup −2} S cm{sup −1} by the solid-state method at 600 °C in wet 5% H{sub 2} in Ar.

  10. Enhanced proton conductivity of yttrium-doped barium zirconate with sinterability in protonic ceramic fuel cells

    International Nuclear Information System (INIS)

    Park, Ka-Young; Seo, Yongho; Kim, Ki Buem; Song, Sun-Ju; Park, Byoungnam; Park, Jun-Young

    2015-01-01

    Highlights: • Report effects of ceramic processing methods on the electrical conductivity of BZY. • Present effects of sintering aids on the conductivity and density of BZY. • CuO is the most effective sintering aid for the BZY. • Polymer gelation is the most effective method in terms of conductivity of BZY. • Grain boundary conductivity of the polymer gelation BZY is higher than others. - Abstract: In this study, we report the effects of various ceramic processing methods with different sintering aids on the relative density, crystallinity, microstructure, and electrical conductivity of proton conducting BaZr 0.85 Y 0.15 O 3−δ (BZY) pellets in details. First, the BZY ceramic pellets are fabricated by the solid-state reactive sintering by adding diverse sintering aids including CuO, NiO, ZnO, SnO, MgO, and Al 2 O 3 . Among these, CuO is found to be the most effective sintering aid in terms of the sintering temperature and total conductivity. However, transition metals as sintering aids have detrimental effects on the electrical conductivity of the BZY electrolytes. Second, the BZY electrolytes have been synthesized by four different methods: the solid-state, combustion, hydrothermal, and polymer gelation methods. The BZY pellets synthesized by the polymer gelation method exhibit dense microstructure with a high relative density of 95.3%. Moreover, the electrical conductivity of the BZY pellets synthesized by the polymer gelation method is higher than those prepared by the solid-state methods under the same test conditions: 1.28 × 10 −2 S cm −1 (by the polymer gelation method) vs. 0.53 × 10 −2 S cm −1 by the solid-state method at 600 °C in wet 5% H 2 in Ar

  11. Pelletizing bagasse for fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bouvet, P.E.; Suzor, N.L.C.

    1980-08-01

    Prior to 1979, the Davies Hawakua Sugar Co. of Hawaii, burned its bagasse in bulk in large furnaces. Because of storage difficulties, however, the company decided to erect a bagasse - pelletizing plant adjacent to its Hawaii sugar factory. The plant, based on the Woodex process, has been very successful and the net energy gain has been calculated in the order of 41%.

  12. Owl Pellet Paleontology

    Science.gov (United States)

    McAlpine, Lisa K.

    2013-01-01

    In this activity for the beginning of a high school Biology 1 evolution unit, students are challenged to reconstruct organisms found in an owl pellet as a model for fossil reconstruction. They work in groups to develop hypotheses about what animal they have found, what environment it inhabited, and what niche it filled. At the end of the activity,…

  13. Fuel rod pellet loading head

    International Nuclear Information System (INIS)

    Howell, T.E.

    1975-01-01

    An assembly for loading nuclear fuel pellets into a fuel rod comprising a loading head for feeding pellets into the open end of the rod is described. The pellets rest in a perforated substantially V-shaped seat through which air may be drawn for removal of chips and dust. The rod is held in place in an adjustable notched locator which permits alignment with the pellets

  14. Control System for the NSTX Lithium Pellet Injector

    International Nuclear Information System (INIS)

    Sichta, P.; Dong, J.; Gernhardt, R.; Gettelfinger, G.; Kugel, H.

    2003-01-01

    The Lithium Pellet Injector (LPI) is being developed for the National Spherical Torus Experiment (NSTX). The LPI will inject ''pellets'' of various composition into the plasma in order to study wall conditioning, edge impurity transport, liquid limiter simulations, and other areas of research. The control system for the NSTX LPI has incorporated widely used advanced technologies, such as LabVIEW and PCI bus I/O boards, to create a low-cost control system which is fully integrated into the NSTX computing environment. This paper will present the hardware and software design of the computer control system for the LPI

  15. Industrial Sintering of Uranium Oxide in a Continuous Furnace

    International Nuclear Information System (INIS)

    Hauser, R.; Porneuf, A.

    1963-01-01

    Under a USAEC-EURATOM research contract, CICAF (Compagnie industrielle de combustibles atomiques frittes) was asked by the French Atomic Energy Commission to design and construct a continuous furnace sintering under a reducing atmosphere at high temperature. The characteristic features of the furnace are automatic operation, rigorous control of presintering and sintering atmospheres, flexibility of temperature regulation so that the thermal cycle can be adjusted to the product to be sintered and high output (5 t of uranium oxide per month). It can operate continuously up to 1700 deg. C, the presintering taking place at a lower temperature (800 deg. C) in a preliminary furnace which forms an integral part of the whole. The sintering atmosphere is cracked ammonia or pure hydrogen; the presintering atmosphere is a mixture o f about 10% hydrogen and 90% nitrogen. The sintered pellets densify to above 97% of theoretical density, with a total dispersion of less than 1%. Structurally, they are equi-axed grains of about 10μm. It was established that the stoichiometric variation of the uranium oxide sintered in a continuous furnace was less than 0.005. (author) [fr

  16. Differences in characteristics of pellets prepared by different pelletization methods.

    Science.gov (United States)

    Häring, Adam; Vetchý, David; Janovská, Lucie; Krejcová, Katerina; Rabisková, Miloslava

    2008-03-01

    Pellets are currently a very popular dosage form for oral application. They can be prepared by several pelletization techniques. Extrusion/spheronization, commonly used in the pharmaceutical industry, and modern agglomeration in a rotoprocessor were the methods chosen for pellet preparation in our study. Theophylline (in 10% to 65% concentration) was the model drug, lactose monohydrate was used as filler, microcrystalline cellulose Avicel PH 101 was thespheronization enhancer, and the wetting agent was purified water. Both techniques led to the formation of pellets of appropriate shape and mechanical properties. Pellets of a higher density, hardness, lower friability, and slightly slower dissolution profiles were obtained by extrusion/spheronization. This method of pelletization also led to production of particles with narrower size distribution and bigger yield of pellets with the requested size.

  17. Synthesis, Sintering, and Electrical Properties of BaCe0.9−xZrxY0.1O3−δ

    Directory of Open Access Journals (Sweden)

    S. Ricote

    2008-01-01

    Full Text Available BaCe0.9−xZrxY0.1O3−δ powders were synthesized by a solid-state reaction. Different contents of cerium and zirconium were studied. Pellets were sintered using either conventional sintering in air at 1700∘C or the Spark Plasma Sintering (SPS technique. The density of the samples sintered by SPS is much higher than by conventional sintering. Higher values of ionic conductivity were obtained for the SPS sample.

  18. The filamentous fungal pellet-relationship between morphology and productivity.

    Science.gov (United States)

    Veiter, Lukas; Rajamanickam, Vignesh; Herwig, Christoph

    2018-04-01

    Filamentous fungi are used for the production of a multitude of highly relevant biotechnological products like citric acid and penicillin. In submerged culture, fungi can either grow in dispersed form or as spherical pellets consisting of aggregated hyphal structures. Pellet morphology, process control and productivity are highly interlinked. On the one hand, process control in a bioreactor usually demands for compact and small pellets due to rheological issues. On the other hand, optimal productivity might be associated with less dense and larger morphology. Over the years, several publications have dealt with aforementioned relations within the confines of specific organisms and products. However, contributions which evaluate such interlinkages across several fungal species are scarce. For this purpose, we are looking into methods to manipulate fungal pellet morphology in relation to individual species and products. This review attempts to address (i) how variability of pellet morphology can be assessed and (ii) how morphology is linked to productivity. Firstly, the mechanism of pellet formation is outlined. Subsequently, the description and analysis of morphological variations are discussed to finally establish interlinkages between productivity, performance and morphology across different fungal species.

  19. Study of production of fuel pellets for a reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Luiz F.F.; Conti, Thadeu N., E-mail: luiz.f.f.mendes@gmail.com, E-mail: tnconti@yahoo.com.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    Nowadays the electrical energy was been used much on society. A method for getting electricity is through nuclear power plants, this power plant uses fission that occurs inside the UO{sub 2} pellets to generate thermal energy that will be transform into electric. The pellets production was made from enriched UF{sub 6} uses some techniques of reprocessing UF{sub 6} gas to UO{sub 2} powder. This reprocessing process done by wet route (Ammonium Diuranate ADU or Ammonium Uranium Carbonate AUC) or by dry route (Fluidized bed or GECO). With getting of UO{sub 2} powder is forwarded to metallurgy where this powder is compacted in cylindrical matrix so that powder take the desired shape, this green pellets are full of the empty spaces (porosity) for this it is sent to the sintering. The sintering consists of a joint of these particles of powders by means of the heating of this green pellets, coming arrive the melting temperature, the UO{sub 2} molecules melting each other so decrease the porosity and increase the density. For the production of fuel pellets the process all most used is wed route by means the AUC ,this process arrive created for replace the ADU because the AUC is a process where less rework for the pore geometry is required compared to DUA. The fluidized bed process is more used in small samples however, for a large amount it becomes unfeasible, moreover the dry route process require more robust materials because of the generation of HF that is highly corrosive and cannot used the UNH (uranyl nitrate hexahydrate) used for recycle materials discarded in manufacturing. (author)

  20. Study of production of fuel pellets for a reactor

    International Nuclear Information System (INIS)

    Mendes, Luiz F.F.; Conti, Thadeu N.

    2017-01-01

    Nowadays the electrical energy was been used much on society. A method for getting electricity is through nuclear power plants, this power plant uses fission that occurs inside the UO 2 pellets to generate thermal energy that will be transform into electric. The pellets production was made from enriched UF 6 uses some techniques of reprocessing UF 6 gas to UO 2 powder. This reprocessing process done by wet route (Ammonium Diuranate ADU or Ammonium Uranium Carbonate AUC) or by dry route (Fluidized bed or GECO). With getting of UO 2 powder is forwarded to metallurgy where this powder is compacted in cylindrical matrix so that powder take the desired shape, this green pellets are full of the empty spaces (porosity) for this it is sent to the sintering. The sintering consists of a joint of these particles of powders by means of the heating of this green pellets, coming arrive the melting temperature, the UO 2 molecules melting each other so decrease the porosity and increase the density. For the production of fuel pellets the process all most used is wed route by means the AUC ,this process arrive created for replace the ADU because the AUC is a process where less rework for the pore geometry is required compared to DUA. The fluidized bed process is more used in small samples however, for a large amount it becomes unfeasible, moreover the dry route process require more robust materials because of the generation of HF that is highly corrosive and cannot used the UNH (uranyl nitrate hexahydrate) used for recycle materials discarded in manufacturing. (author)

  1. Three-dimensional simulation of viscous-flow agglomerate sintering.

    Science.gov (United States)

    Kirchhof, M J; Schmid, H -J; Peukert, W

    2009-08-01

    The viscous-flow sintering of different agglomerate particle morphologies is studied by three-dimensional computer simulations based on the concept of fractional volume of fluid. For a fundamental understanding of particle sintering characteristics, the neck growth kinetics in agglomerate chains and in doublets consisting of differently sized primary particles is investigated. Results show that different sintering contacts in agglomerates even during the first stages are not completely independent from each other, even though differences are small. The neck growth kinetics of differently sized primary particles is determined by the smaller one up to a size difference by a factor of approximately 2, whereas for larger size differences, the kinetics becomes faster. In particular, the agglomerate sintering kinetics is investigated for particle chains of different lengths and for different particle morphologies each having ten primary particles and nine initial sintering contacts. For agglomerate chains, the kinetics approximately can be normalized by using the radius of the fully coalesced sphere. In general, different agglomerate morphologies show equal kinetics during the first sintering stages, whereas during advanced stages, compact morphologies show significantly faster sintering progress than more open morphologies. Hence, the overall kinetics cannot be described by simply using constant morphology correction factors such as fractal dimension or mean coordination number which are used in common sintering models. However, for the first stages of viscous-flow agglomerate sintering, which are the most important for many particle processes, a sintering equation is presented. Although we use agglomerates consisting of spherical primary particles, our methodology can be applied to other aggregate geometries as well.

  2. Preparation and evaluation of pellets using acacia and tragacanth by extrusion-spheronization.

    Science.gov (United States)

    Akhgari, A; Abbaspour, M R; Pirmoradi, S

    2011-01-01

    Extrusion-spheronization is an established technique for the production of pellets for pharmaceutical applications. In this study, the feasibility and influence of the incorporation of acacia, by itself and in combination with tragacanth, on the ability of formulations containing 2 model of drugs (ibuprofen and theophylline) to form spherical pellets by extrusion-spheronization was investigated. Formulations containing different ratios of acacia and tragacanth (8:2, 9:1, and 10:0) and different drug concentrations (20%, 40%, and 60%) were prepared, on the basis of a 3(2) full factorial design. Pellet properties, such as aspect ratio, sphericity (image analysis), crushing strength and elastic modulus (mechanical tests), mean dissolution time, and dissolution profiles were evaluated. The effect of particular factors on responses was determined by linear regression analysis. The sphericity, drug release rate, and the mechanical properties of the pellets were affected by the amounts and types of the drugs, and the ratio of the gums. Acacia, relative to tragacanth, produced pellets with higher mechanical strength and a faster drug release rate. Addition of small amounts of tragacanth to ibuprofen formulations resulted in matrix pellets with slow drug release. The results showed that acacia and tragacanth can be used successfully as 2 natural binders in the pellet formulations.

  3. Preparation and Evaluation of Pellets Using Acacia and Tragacanth by Extrusion-Spheronization

    Directory of Open Access Journals (Sweden)

    S. Pirmoradi

    2011-12-01

    Full Text Available Background and the purpose of the study: Extrusion-spheronization is an established technique for the production of pellets for pharmaceutical applications. In this study, the feasibility and influence of the incorporation of acacia, by itself and in combination with tragacanth, on the ability of formulations containing 2 model of drugs (ibuprofen and theophylline to form spherical pellets by extrusion-spheronization was investigated.Material and Methods: Formulations containing different ratios of acacia and tragacanth (8:2, 9:1, and 10:0 and different drug concentrations (20%, 40%, and 60% were prepared, on the basis of a 32 full factorial design. Pellet properties, such as aspect ratio, sphericity (image analysis, crushing strength and elastic modulus (mechanical tests, mean dissolution time, and dissolution profiles were evaluated. The effect of particular factors on responses was determined by linear regression analysis.Results: The sphericity, drug release rate, and the mechanical properties of the pellets were affected by the amounts and types of the drugs, and the ratio of the gums. Acacia, relative to tragacanth, produced pellets with higher mechanical strength and a faster drug release rate. Addition of small amounts of tragacanth to ibuprofen formulations resulted in matrix pellets with slow drug release.Conclusion: The results showed that acacia and tragacanth can be used successfully as 2 natural binders in the pellet formulations.

  4. Pellets standard on the way

    International Nuclear Information System (INIS)

    Laeng, H.-P.

    2001-01-01

    This short article introduces the Swiss standard that has been adapted from the German standard for heating pellets made of untreated wood. The various requirements placed on the materials used in the manufacture of the pellets and their influence on the pollution emissions produced by boilers and ovens using the pellets as a heating fuel are listed. Further points in the standard referring to declarations to be made by the manufacturer, size and specific weight of the pellets and instructions for the storage and burning of the pellets are discussed

  5. Nuclear fuel pellet loading apparatus

    International Nuclear Information System (INIS)

    Gerkey, K.S.

    1979-01-01

    An automatic apparatus for loading a predetermined amount of nuclear fuel pellets into a nuclear fuel element to be used in a nuclear reactor is described. The apparatus consists of a vibratory bed capable of supporting corrugated trays containing rows of nuclear fuel pellets and arranged in alignment with the open ends of several nuclear fuel elements. A sweep mechanism is arranged above the trays and serves to sweep the rows of fuel pellets onto the vibratory bed and into the fuel element. A length detecting system, in conjunction with a pellet stopping mechanism, is also provided to assure that a predetermined amount of nuclear fuel pellets are loaded into each fuel element

  6. Pneumatic pellet injector for JET

    International Nuclear Information System (INIS)

    Andelfinger, C.; Buechl, K.; Jacobi, D.; Sandmann, W.; Schiedeck, J.; Schilling, H.B.; Weber, G.

    1983-07-01

    Pellet injection is a useful tool for plasma diagnostics of tokamaks. Pellets can be applied for investigation of particle, energy and impurity transport, fueling efficiency and magnetic surfaces. Design, operation and control of a single shot pneumatic pellet gun is described in detail including all supplies, the vacuum system and the diagnostics of the pellet. The arrangement of this injector in the torus hall and the interfaces to the JET system and CODAS are considered. A guide tube system for pellet injection is discussed but it will not be recommended for JET. (orig.)

  7. Sintering of beryllium oxide

    International Nuclear Information System (INIS)

    Caillat, R.; Pointud, R.

    1955-01-01

    This study had for origin to find a process permitting to manufacture bricks of beryllium oxide of pure nuclear grade, with a density as elevated as possible and with standardized shape. The sintering under load was the technique kept for the manufacture of the bricks. Because of the important toxicity of the beryllium oxide, the general features for the preliminary study of the sintering, have been determined while using alumina. The obtained results will be able to act as general indication for ulterior studies with sintering under load. (M.B.) [fr

  8. Behaviour of (Th, U)O2 microspheres under compression tests and pelletization

    International Nuclear Information System (INIS)

    Ferreira, R.A.N.

    1982-12-01

    The interrelation between the behaviour of isolated microspheres in compression tests and the microstructure of sintered pellets obtained with these microspheres, was investigated. Various batches of (Th, 5 w/o U)O 2 microspheres were produced applying the so-called gel process. The production parameters were diversified both as to the composition and to the heat treatments. The resulting products underwent compression tests in an universal tension and compression machine as single microspheres and, as bulk material, were compacted and sintered. The results of the compression tests revealed the existence of two distinct classes of fragmentation behaviour. Each of these classes causes a distinct behaviour during the pelletization, too, resulting in fuel pellets with quite different microstructures. It was evidenced that there is a relationship between these differences in the microstructure and the behaviour of the single microspheres in the compression test. (Author) [pt

  9. Immobilization of high-level wastes into sintered glass: 1

    International Nuclear Information System (INIS)

    Russo, D.O.; Messi de Bernasconi, N.; Audero, M.A.

    1987-01-01

    In order to immobilize the high-level radioactive wastes from fuel elements reprocessing, borosilicate glass was adopted. Sintering experiments are described with the variety VG 98/12 (SiO 2 , TiO 2 , Al 2 O 3 , B 2 O 3 , MgO, CaO and Na 2 O) (which does not present devitrification problems) mixed with simulated calcinated wastes. The hot pressing line (sintering under pressure) was explored in two variants 1: In can; 2: In graphite matrix with sintered pellet extraction. With scanning electron microscopy it is observed that the simulated wastes do not disolve in the vitreous matrix, but they remain dispersed in the same. The results obtained point out that the leaching velocities are independent from the density and from the matrix type employed, as well as from the fact that the wastes do no dissolve in the matrix. (M.E.L.) [es

  10. Physical chemistry and modelling of the sintering of actinide oxides

    International Nuclear Information System (INIS)

    Lechelle, Jacques

    2013-01-01

    This report gives a synthesis of the work I have carried out or to which I have numerically contributed to from 1996 up to 2012 in the Department of Plutonium Uranium and minor Actinides in Cadarache CEA Center. Their main goal is the study and the modeling of the sintering process of nuclear fuels which is the unifying thread of this document. Both in order to take into account the physical and chemical features of the actinide bearing oxide material and in order to combine the different transport phenomena leading to sintering, a sub-granular scale model is under development. Extension to a varying chemical composition as well as exchanges with the gaseous phase are foreseen. A simulation on a larger scale (pellet scale) is ongoing in the framework of a PhD thesis. Validation means have been tested with (U,Pu)O 2 material on the scale of the pellet (Small Angle Neutron Diffusion), on the scale of powder granules (X-Ray High Resolution Micro-Tomography) and with CeO 2 at the 'Institut de Chimie Separative' in Marcoule on a single crystal scale (Environmental Scanning Electron Microscope). The required microstructure homogeneity for nuclear fuels has led to a campaign of experimental studies about the role of Cr 2 O 3 as a sintering aid. Whole of these studies improve our understanding of fuel sintering and hence leads to an improved mastering of this process. (author) [fr

  11. Manufacturing and characterization of molybdenum pellets used as targets for 99mTc production in cyclotron

    International Nuclear Information System (INIS)

    Cieszykowska, Izabela; Janiak, Tomasz; Barcikowski, Tadeusz; Mielcarski, Mieczysław; Mikołajczak, Renata; Choiński, Jarosław; Barlak, Marek; Kurpaska, Łukasz

    2017-01-01

    The method of 100 Mo metallic target preparation for production of 99m Tc by proton irradiation in 100 Mo(p,2 n) 99m Tc reaction was demonstrated. For this purpose, pressing of molybdenum powder into pellets and their subsequent sintering in reductive atmosphere were applied. The influence of parameters such as molybdenum mass and time of both pressing and sintering on the 100 Mo target durability was investigated. Under the optimized conditions, 100 Mo metallic pellet targets with density of 9.95±0.06 g/cm 3 were obtained. Morphology and structure of pressed pellets before and after sintering were studied by using standard optical microscope and Scanning Electron Microscope (SEM). Nanoindentation technique was used to investigate the mechanical properties such as nanohardness and Young modulus. Prepared 100 Mo pellets were successfully irradiated with protons and 99m Tc was efficiently isolated. - Highlights: • Pressing and sintering of 100 Mo powder into pellets. • Optimization of 100 Mo target manufacture process. • Determination of nanohardness of prepared 100 Mo targets. • Irradiation of self-supporting 100 Mo target in cyclotron.

  12. Opportunities for Pellet Trade - Towards a Single European Pellet Market

    International Nuclear Information System (INIS)

    Pigaht, Maurice; Janssen, Rainer; Rutz, Dominik; Boehm, Thorsten; Vasen, Norbert; Vegas, Laura; Karapanagiotis, Nicolas

    2006-01-01

    The potential for Pellets trade in Europe was researched and assessed. Such trade is of key importance for the development of a European pellet market of sufficient supply, demand, price and quality standards. Three target markets were taken as case studies for the trade assessment: Greece, Spain and Italy. All three markets stand to profit greatly from international trade. For these markets, pellet imports could supply the basis for the development of a domestic boiler market. At the same time, pellet exports would allow the planning of larger pellet production plants. Whilst these additional costs amount to some 10-20% of the Pellets price, they are financially acceptable, especially for new markets and 'peaks' in the demand/supply of established markets

  13. Fabrication of (Th-Pu) MOX fuel pellets using CAP route for experimental irradiation

    International Nuclear Information System (INIS)

    Nehete, Y.G.; Shelke, B.K.; Shotriya, S.K.; Subbarayal, K.; Kumar, Neeraj; Khot, P.M.; Surendra, B.; Yadav, M.K.; Mishra, A.K.; Afzal, Mohd; Panakkal, J.P.

    2011-01-01

    Advanced Fuel Fabrication Facility (AFFF), Tarapur is an industrial scale plant for the fabrication of MOX fuel for thermal and fast reactor. Mixed oxide fuels of different composition have been fabricated in this facility for both thermal and fast reactors. In order to simulate actual condition in Advanced Heavy Water Reactors (AHWR), (Th-Pu) MOX fuel pins of different % of PuO 2 were fabricated at AFFF, BARC Tarapur for irradiation in research reactor. ThO 2 -1% PuO 2 was fabricated by conventional powder pelletization (POP) as well as Coated agglomerate pelletization (CAP) route. Powder pelletization route involves co-milling of milled ThO 2 powder with calcined PuO 2 , precompaction, granulation, final compaction followed by sintering in reducing atmosphere at 1650 deg C. Coated Agglomerate Pelletization (CAP) route involves making spheroids of milled ThO 2 powder using extrusion and spherodization technique then coating of ThO 2 spheroids with desired amount of calcined PuO 2 powder followed by final compaction and sintering in reducing atmosphere. Necessary modifications in process parameters have been made and the tool design was so chosen to get sintered to sized pellet to avoid grinding. Pellets fabricated by CAP route meets all desired specification like POP route. It also has the advantages over POP route like small number of process steps and reduction of man-rem. This paper highlights feasibility of CAP route for fabrication of (Th-Pu)O 2 fuel and characterization of fuel pellets. (author)

  14. The effect of U3O-8 addition on the UO2 pellet

    International Nuclear Information System (INIS)

    Indrati, Y.T.; Syarif, D. G.; Handayani, A.

    1998-01-01

    The purpose of varied U 3 O 8 addition on the UO 2 pellet fabrication is to from 1-3 mu pores. The green pellets, compacted with 3 ton/cm 2 , are a mixture powder of UO 2 , TiO 2 (0.1% weight) and varied U 3 O 8 (0-12.5% weight). The green pellets were presintered by H2 atmosphere. The presintered pellets were put on the ceramic crucibles and than those were put on the SS 316 tube with argon atmosphere. The 1400 o C sintering was hold with the soaking time 3 hr and the same rate of heating and cooling 150 o C/hr. The UO 2 pellet with 5% (weight) U 3 O 8 addition has 95.17% of theoretic density and 548.4 ±6.57 VH. Based on the identification of microstructure of pellet, it is not acceptable for nuclear fuel although pellet has 10.02 mu on grain size and 1.3 mu on closed pore size. By the diffractometer X-ray, crystal structure of pellet is face centered cubic (FCC) with the O/U ratio is 2.08

  15. Formulation and evaluation of olanzapine matrix pellets for controlled release.

    Science.gov (United States)

    Vishal Gupta, N; Gowda, Dv; Balamuralidhara, V; Mohammed Khan, S

    2011-01-01

    Olanzapine is an antipsychotic used in treatment of schizophrenia. This research was carried out to design oral controlled release matrix pellets of water insoluble drug Olanzapine (OZ), using blend of Sodium Alginate (SA) and Glyceryl Palmito-Stearate (GPS) as matrix polymers, micro crystalline cellulose (MCC) as spheronizer enhancer and Sodium Lauryl Sulphate (SLS) as pore forming agent. OZ formulations were developed by the pelletization technique by drug loaded pellets and characterized with regard to the drug content, size distribution, Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction study (XRD). Stability studies were carried out on the optimized formulation for a period of 90 days at 40±2 °C and 75±5% relative humidity. The drug content was in the range of 93.34-98.12%. The mean particle size of the drug loaded pellets was in the range 1024 to 1087µm. SEM photographs and calculated sphericity factor confirmed that the prepared formulations were spherical in nature. The compatibility between drug and polymers in the drug loaded pellets was confirmed by DSC and FTIR studies. Stability studies indicated that pellets are stable. XRD patterns revealed the crystalline nature of the pure OZ. Loose surface crystal study indicated that crystalline OZ is present in all formulations and more clear in formulation F5. Drug release was controlled for more than 24 hrs and mechanism of the drug release followed by Fickian diffusion. It may be concluded that F5 is an ideal formulation for once a day administration.

  16. Pelleting properties and pellet quality of apple pomace

    Directory of Open Access Journals (Sweden)

    Maslovarić Marijana D.

    2015-01-01

    Full Text Available Apple pomace (AP is the main by-product of apple juice production. It is a residue after pressing of apples for juice extraction. AP is an organic material, with high moisture and sugar content, therefore its direct disposal on landfills or land spreading causes serious environmental pollution. One of the solutions for further exploitation of AP could be its utilization as animal feed. However, fresh AP is quite perishable, and it must be preserved in order to be stored and used over a long period of time. The aim of this research was to investigate the possibility to transform AP to a stabile form which would be acceptable for feed manufacturers in terms of stability, storage and handling. For this purpose, pelleting process was used and pelleting properties of AP were evaluated. Before pelleting, dried AP was divided into three batches, which were conditioned only by water addition in order to achieve different moisture contents of the material: 10% of moisture for the first batch, 13% for the second batch and 16% for the third batch. According to the obtained values for Pellet Durability Index (PDI and pellet hardness, pellet quality for all examined AP batches was very high. Increased moisture content of AP led to the reduction in energy consumption of the pellet press, thus providing energy saving in the pelleting process. Pelleting process also caused strong increase of AP bulk density which is positive in terms of transportation and storage.

  17. Manufacturing at industrial level of UO2 pellets for the fuel elements of the Atucha I Nuclear Power Plant

    International Nuclear Information System (INIS)

    Dyment, I.G.; Noguera Rojas, Francisco

    1982-01-01

    The interest to produce fuel elements within a policy of self sufficiency arose with the installation of Atucha I. The first steps towards this goal consisted in processing the uranium oxide, transforming it into fuel pellets of high density. The developments towards the fabrication of said pellets, performed by CNEA since 1968, first at a laboratory level and afterwards on an industrial scale, allowed CNEA to obtain its own technological capability to produce 400 kg of UO 2 per day. The fuel pellets manufacturing method developed by CNEA is a powder-metallurgical process, which, besides conventional equipment, involves the use of special equipment that required the performance of systematic testing programmes, as well as special training at operational level. The developed processes respond to a modern and advanced technology. A general scheme of the process, starting with a directly sinterable UO 2 powder, is described, including compacting of the powder into pellets, sintering, control of the temperature in the sintering and reduction zones and of the time of permanence in both zones, and cylindric rectifying of the pellets. During the whole process, specialized personnel controls the operations, after which the material is released by the Quality Control Department. The national contribution to the manufacturing technology of the pellets for fuel elements of power and research reactors was of 100%. (M.E.L.) [es

  18. Degradation of copepod fecal pellets

    DEFF Research Database (Denmark)

    Poulsen, Louise K.; Iversen, Morten

    2008-01-01

    Copepod fecal pellets are often degraded at high rates within the upper part of the water column. However, the identity of the degraders and the processes governing the degradation remain unresolved. To identify the pellet degraders we collected water from Oresund (Denmark) approximately every...... second month from July 2004 to July 2005. These water samples were divided into 5 fractions (pellet degradation rate and species composition of the plankton from triplicate incubations of each fraction and a known, added...... amount of fecal pellets. The total degradation rate of pellets by the natural plankton community of Oresund followed the phytoplankton biomass, with maximum degradation rate during the spring bloom (2.5 +/- 0.49 d(-1)) and minimum (0.52 +/- 0.14 d(-1)) during late winter. Total pellet removal rate ranged...

  19. Agglomeration behaviour of steel plants solid waste and its effect on sintering performance

    Directory of Open Access Journals (Sweden)

    Prince Kumar Singh

    2017-07-01

    Full Text Available Recycling has been the fascinating topic among the researchers for all times. The present study shows the recycling of steel plant's solid wastes as blast furnace flue dust and sludge towards agglomeration and their use in the production of sinter. These wastes consist of metal oxides and coke fines as a valuable material with some alkali oxides. Using these wastes as it is in the form of fines exacerbate the further processing. Pellets of these wastes are prepared with three types of binders as molasses, dextrin and bentonite. The result reveals that properties as compressive strength, shatter strength, are better in the case of bentonite binder having the productivity of the disc pelletizer machine as 75. After that, these macro pellets used for sintering with iron ore and other ingredients in pot type, down draft laboratory grade sintering machine, which shows very high productivity and good mechanical properties of the sinter as well. The microstructural analysis reveals the presence of re-oxidized hematite and a little bit of a magnetite phase with some slag phases, which confirmed later by XRD analysis. Results also show the decrease in coke rate, i.e. coke consumption to produce sinter and at the same time, this process is highly eco-friendly.

  20. Sintering and thermal ageing studies of zirconia - yttria ceramics by impedance spectroscopy

    International Nuclear Information System (INIS)

    Florio, Daniel Zanetti de

    1998-01-01

    ZrO 2 :8 mol %Y 2 O 3 solid electrolyte ceramic pellets have been prepared with powders of three different origins: a Nissan (Japan) commercial powder, a powder obtained by the coprecipitation technique at IPEN, and the mixing of powder oxides (ZrO 2 produced at a Pilot Plant at IPEN and 99.9% pure Y 2 O 3 of USA origin). These starting powders have been analysed by the following techniques: X-ray fluorescence for yttrium content, X-ray diffraction for structural phase content, sedimentation for particle size distribution, gas adsorption (BET) for surface area determination, and transmission electron microscopy for average particle size determination. Pressed ceramic pellets have been analysed by dilatometry to evaluate the sintering stages. Sintered pellets have been characterized by X-ray diffraction for phase analysis and scanning electron microscopy for grain morphology analysis. Impedance spectroscopy analysis have been carried out to follow thermal ageing of zirconia-yttria solid electrolyte at 600 deg C, the working temperature of permanent oxygen sensor, and to study sintering kinetics. The main results show that ageing at 600 deg C decreases the emf sensor response in the first 100 h to a steady value. Moreover, sintering studies by impedance spectroscopy allowed for finding correlations between electrical parameters, sintering kinetics and grain growth mechanisms. (author)

  1. Pellets direct from the forest

    International Nuclear Information System (INIS)

    Keel, A.

    2006-01-01

    This article takes a look at developments in the market for wood pellets and their production from forest wood. The general situation in the booming pellets market is reviewed and the potential of this climate-neutral form of heating is discussed. Figures and prognoses on the use of wood pellets are presented. In particular, the potential for the use of forestry wood supplies to augment the use of wood wastes and sawdust from sawmills is looked at

  2. Density gradients in ceramic pellets measured by computed tomography

    International Nuclear Information System (INIS)

    Sawicka, B.D.; Palmer, B.J.F.

    1986-07-01

    Density gradients are of fundamental importance in ceramic processing and computed tomography (CT) can provide accurate measurements of density profiles in sintered and unsintered ceramic parts. As a demonstration of this potential, the density gradients in an unsintered pellet pressed from an alumina powder were measured by CT scanning. To detect such small density gradients, the CT images must have good density resolution and be free from beam-hardening effects. This was achieved by measuring high-contrast (low-noise) images with the use of an Ir-192 isotopic source. A beam-hardening correction was applied. The resulting images are discussed relative to the transmission of forces through the powder mass during the pelletizing process

  3. Contribution to the study of UO2 pellet fabrication

    International Nuclear Information System (INIS)

    Fogaca Filho, N.; Gentile, E.F.; Mourao, M.B.; Souza Santos, T.D. de; Haydt, H.M.

    1977-01-01

    The establishment of a set of parametric comparisons related to UO 2 powders of two different origins as the ammonium diuranate and the ammonium uranyl carbonate is presented. It is emphasized the importance due to the pressing capability of the powders and the requirement for homogeneous microstructure for both, the pore distribution and the grain size. In order to establish the parameters of comparison, all the required normal tests for the in-process control of fabrication of fuel elements for nuclear power reactors were performed, particularly to the re-sintering test, in view of the evaluation of dimensional stability of the pellets [pt

  4. Morphological analysis and modelling of sintering and of sintered materials

    International Nuclear Information System (INIS)

    Jernot, Jean-Paul

    1982-01-01

    This research thesis addresses the study of solid phase sintering of metallic powders, and aims at describing as precisely as possible the different involved matter transport mechanisms, first by using a thermodynamic approach to sintering. Sintering diagrams are also used to determine prevailing mechanisms. The microstructure of sintered materials has been studied by using image quantitative analysis, thus by using a morphological approach to sintering. Morphological parameters allow, on the one hand, the evolution of powders during sintering to be followed, and, on the other hand, sintered products to be correctly characterised. Moreover, the author reports the study of the evolution of some physical properties of sintered materials with respect to their microstructure parameters. This leads to the development of a modelling of the behaviour of these materials [fr

  5. Preparation of pellets containing highly soluble drug by extrusion/spheronisation and coating with Kollicoat® SR 30D

    OpenAIRE

    Andreazza,Itamar Francisco; Ferraz,Humberto Gomes

    2011-01-01

    The aim of this study was to prepare and evaluate the pellets, containing a highly soluble drug (ascorbic acid), by the extrusion-spheronization process and coated with a release controlling polymer. The coating (undertaken in a fluid bed) was applied to three batches of the pellets with a dispersion of Kollicoat® SR 30 D, with each batch of pellets receiving a different level of polymer (5.07; 8.26 and 10.35%). The coated pellets were evaluated for sphericity by imaging analysis and comparat...

  6. Solid hydrogen pellet injection into the ORMAK Tokamak

    International Nuclear Information System (INIS)

    Foster, C.A.; Colchin, R.J.; Milora, S.L.; Kim, K.; Turnbull, R.J.

    1977-06-01

    Solid hydrogen spheres were injected into the ORMAK tokamak as a test of pellet refueling for tokamak fusion reactors. Pellets 70 μm and 210 μm in diameter were injected with speeds of 91 m/sec and 100 m/sec, respectively. Each of the 210-μm pellets added about 1% to the number of particles contained in the plasma. Excited neutrals, ablated from these hydrogen spheres, emitted light which was monitored either by a photomultiplier or by a high speed framing camera. From these light signals it was possible to measure pellet lifetimes, ablation rates, and the spatial distribution of hydrogen atoms in the ablation clouds. The average measured lifetime of the 70-μm pellets was 422 μsec, and the 210-μm spheres lasted 880 μsec under bombardment by the plasma. These lifetimes and measured ablation rates are in good agreement with a theoretical model which takes into account shielding of plasma electrons by hydrogen atoms ablated from spherical hydrogen ice

  7. Recent advances in pelletization technique for oral drug delivery: a review.

    Science.gov (United States)

    Rahman, M Akhlaquer; Ahuja, Alka; Baboota, S; Bhavna; Bali, Vikas; Saigal, Nitin; Ali, Javed

    2009-01-01

    Multiparticulate dosage forms are receiving a great deal of attention as alternative system for oral drug delivery. The present review outlines the recent findings on the manufacturing and evaluation of spherical pellets published over the past decade. The techniques namely extrusion-spheronization, hot melt extrusion, freeze pelletization, cryopelletization have been discussed along with parameters affecting pelletization. Evaluation of quality of the pellets is discussed with reference to the size distribution, shape, surface morphology, specific surface area, friability, tensile strength, density, porosity, disintegration time and in vitro dissolution studies of pellets. The use of multiparticulate dosage forms as a promising system for the oral delivery of many therapeutic agents has also been examined in the current review.

  8. Hot-melt extrusion of sugar-starch-pellets.

    Science.gov (United States)

    Yeung, Chi-Wah; Rein, Hubert

    2015-09-30

    Sugar-starch-pellets (syn. sugar spheres) are usually manufactured through fluidized bed granulation or wet extrusion techniques. This paper introduces hot-melt extrusion (HME) as an alternative method to manufacture sugar-starch-pellets. A twin-screw extruder coupled with a Leistritz Micro Pelletizer (LMP) cutting machine was utilized for the extrusion of different types (normal-, waxy-, and high-amlyose) of corn starch, blended with varying amounts of sucrose. Pellets were characterized for their physicochemical properties including crystallinity, particle size distribution, tensile strength, and swelling expansion. Furthermore, the influence of sugar content and humidity on the product was investigated. Both sucrose and water lowered the Tg of the starch system allowing a convenient extrusion process. Mechanical strength and swelling behavior could be associated with varying amylose and amylopectin. X-ray powder diffractometric (XRPD) peaks of increasing sucrose contents appeared above 30%. This signified the oversaturation of the extruded starch matrix system with sucrose. Otherwise, had the dissolved sucrose been embedded into the molten starch matrix, no crystalline peak could have been recognized. The replacement of starch with sucrose reduced the starch pellets' swelling effect, which resulted in less sectional expansion (SEI) and changed the surface appearance. Further, a nearly equal tensile strength could be detected for sugar spheres with more than 40% sucrose. This observation stands in good relation with the analyzed values of the commercial pellets. Both techniques (fluidized bed and HME) allowed a high yield of spherical pellets (less friability) for further layering processes. Thermal influence on the sugar-starch system is still an obstacle to be controlled. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Sintering of Synroc D

    International Nuclear Information System (INIS)

    Robinson, G.

    1982-01-01

    Sintering has been investigated as a method for the mineralization and densification of high-level nuclear defense waste powder. Studies have been conducted on Synroc D composite powder LS04. Optimal densification has been found to be highly dependent on the characteristics of the starting material. Powder subjected to milling, which was believed to reduce the level of agglomeration and possibly particle size, was found to densify better than powder not subjected to this milling. Densities of greater than 95% of theoretical could be achieved for samples sintered at 1150 to 1200 0 C. Mineralogy was found to be as expected for Synroc D for samples sintered in a CO 2 /CO atmosphere where the Fe +2 /Fe +3 ratio was maintained at 1.0 to 5.75. In a more oxidizing, pure CO 2 atmosphere a new phase, not previously identified in Synroc D, was found

  10. SinterHab

    Science.gov (United States)

    Rousek, Tomáš; Eriksson, Katarina; Doule, Ondřej

    2012-05-01

    This project describes a design study for a core module on a Lunar South Pole outpost, constructed by 3D printing technology with the use of in-situ resources and equipped with a bio-regenerative life support system. The module would be a hybrid of deployable (CLASS II) and in-situ built (CLASS III) structures. It would combine deployable membrane structures and pre-integrated rigid elements with a sintered regolith shell for enhanced radiation and micrometeorite shielding. The closed loop ecological system would support a sustainable presence on the Moon with particular focus on research activities. The core module accommodates from four to eight people, and provides laboratories as a test bed for development of new lunar technologies directly in the environment where they will be used. SinterHab also includes an experimental garden for development of new bio-regenerative life support system elements. The project explores these various concepts from an architectural point-of-view particularly, as they constitute the building, construction and interior elements. The construction method for SinterHab is based on 3D printing by sintering of the lunar regolith. Sinterator robotics 3D printing technology proposed by NASA JPL enables construction of future generations of large lunar settlements with little imported material and the use of solar energy. The regolith is processed, placed and sintered by the Sinterator robotics system which combines the NASA ATHLETE and the Chariot remotely controlled rovers. Microwave sintering creates a rigid structure in the form of walls, vaults and other architectural elements. The interior is coated with a layer of inflatable membranes inspired by the TransHab project. The life-support system is mainly bio-regenerative and several parts of the system are intrinsically multifunctional and serve more than one purpose. The plants for food production are also an efficient part of atmosphere revitalization and water treatment. Moreover

  11. Owl Pellets and Crisis Management.

    Science.gov (United States)

    Anderson, Tom

    2002-01-01

    Describes a press conference that was used as a "teachable moment" when owl pellets being used for instructional purposes were found to be contaminated with Salmonella. The incident highlighted the need for safe handling of owl pellets, having a crisis management plan, and the importance of conveying accurate information to concerned parents.…

  12. Pelletizing properties of torrefied spruce

    Science.gov (United States)

    Wolfgang Stelte; Craig Clemons; Jens K. Holm; Anand R. Sanadi; Jesper Ahrenfeldt; Lei Shang; Ulrik B. Henriksen

    2011-01-01

    Torrefaction is a thermo-chemical conversion process improving the handling, storage and combustion properties of wood. To save storage space and transportation costs, it can be compressed into fuel pellets of high physical and energetic density. The resulting pellets are relatively resistant to moisture uptake, microbiological decay and easy to comminute into small...

  13. Nanostructured CoSi Obtained by Spark Plasma Sintering

    Science.gov (United States)

    Longhin, Marco; Viennois, Romain; Ravot, Didier; Robin, Jean-Jacques; Villeroy, Benjamin; Vaney, Jean-Baptiste; Candolfi, Christophe; Lenoir, Bertrand; Papet, Philippe

    2015-06-01

    Cobalt monosilicide is a cheap, environmentally friendly thermoelectric material for medium temperatures (200-700°C). While its power factor is similar to the state-of-the-art thermoelectric materials, its thermal conductivity is too large to reach high ZT values. Nanostructuring might be an interesting strategy to reduce the phonon mean free path thereby improving the thermoelectric performance. In this paper, we report on a 35% reduction of the thermal conductivity of n-type CoSi by a nanostructuring approach. CoSi nanostructured powders were synthesized by arc melting, followed by 4° h mechanical milling. By optimizing the spark plasma sintering thermal and pressure cycle, pellets with 5â€"10% porosity were obtained. During sintering, a small amount of Co2Si extra phase appeared and grains coarsened. After sintering, the pellets remained nanostructured, with an averaged grain size of 70 nm. The reduction of thermal conductivity is ascribed to a decrease in both the electronic and lattice contributions. The former is directly related to a decrease in the electrical conductivity, which appears to be the limiting factor preventing nanostructured CoSi from reaching enhanced thermoelectric performances.

  14. Recycling of Manganese Secondary Raw Material Via Cold-Bond Pelletizing Process

    International Nuclear Information System (INIS)

    Ahmed, Y.M.Z.; Mohamed, F.M.

    2004-01-01

    Large quantities of fines were produced during the shipping, transportation, handling and storage of manganese ore sinter imported from different countries to Sinai Company for ferromanganese production. These fines are generally considered as valuable secondary raw materials. Hence, they have a potential to be recycled back to the submerged arc furnace after having been agglomerated. For agglomerates to be considered as feed materials for submerged arc furnace they must have sufficient room temperature strength. Cold-bonded penalization process offers an economically attractive and environmentally viable method for achieving this. Ordinary Portland cement was used in this investigation for the purpose of producing a suitable cold-bonded pellet from such fines. In this investigation, the effect of adding different percentages of Portland cement on the mechanical properties of both green and pellet dried at room temperature for 1, 3, 7, 14, and 28 days of normal curing were studied. The results revealed that, although the compressive strength of green pellets improved with the increase of the amount of cement added. retardation in pellet drop strength was reported. Whereas, the increase in both the cement content and time of drying leads to increase in the mechanical properties of pellets normally cured at room temperature. pellets obtain with the addition of 9% cement shows reasonable mechanical properties to be charged in the submerged are furnace. ferromanganese alloy having a standard range composition was produced in a laboratory submerged are furnace using such pellets

  15. Thermal performance prediction of UO2 pellet partly containing 9%w tungsten network

    International Nuclear Information System (INIS)

    Suwardi

    2008-01-01

    Sintered UO 2 exhibits very stable in reactor core compared to UC, UN, U metal and its alloys. However, its thermal conductivity is very low (2.about.5 W/m K), that limits its performance. UO 2 pellet containing Tungsten network invented by Song improves considerably its conductivity. The paper reports an analysis of thermal performance for UO 2 pellet that contains partly or wholly with 9% b. of Tungsten. The tungsten network having a high melting point and excellent thermal conductivity is continuously formed around UO 2 grains. Since the presence of network decreases the amount of fissile material and the burn up of fissile material is higher in the near surface zone of pellet but high temperature zone that releases low conductivity fission gas to the gap located in inner part of pellet, the analysis has been done for different outer radial-portion of tungsten-free pellet. The analysis takes into account the correction factor for pellet conductivity related to both pore and temperature distribution and high burn up effect. The gap conductance has been considered invariable since decrease caused by wider gap size related to lower pellet expansion is compensated by increase caused by fewer of refractory fission gas released. The results (47 kw/m, 40% burnup) show temperature decrease in all of pellet position containing W network. Pellet containing 9%b. tungsten network lower consecutively its center line temperature from 1578 to 1406, 1292, 1231, 1192, 1111, and 1038 deg C for 0, 50, 67, 75, 80, 90, and 100 % portion of network. An 80 to 90 % portion of inner pellet containing tungsten network can be considered a best fuel design. This preliminary analysis is prospective and more realistic one is recommended. (author)

  16. Nuclear energy - Uranium dioxide pellets - Determination of density and volume fraction of open and closed porosity. 2. ed. 2. ed.

    International Nuclear Information System (INIS)

    2008-01-01

    This International Standard describes a method for determining the chlorine and fluorine concentrations in uranium dioxide and in sintered fuel pellets by pyrohydrolysis of samples, followed either by liquid ion-exchange chromatography or by selective electrode measurement of chlorine and fluorine ions. Many ion-exchange chromatography systems and ion-selective electrode measurement systems are available

  17. Nano pores evolution in hydroxyapatite microsphere during spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Lin C.

    2011-01-01

    Full Text Available Micron-spherical granules of hydroxyapatite (HAp nanoparticles were prepared by powder granulation methods. Through subsequent sintering, porous HAp microspheres with tailored pore and grain framework structures were obtained. Detailed microstructure investigation by SEM and TEM revealed the correlation of the pore structure and the necking strength with the sintering profiles that determine the coalescence features of the nanoparticles. The partially sintered porous HAp microspheres containing more than 50% porosity consisting of pores and grains both in nano-scale are active in inducing the precipitation of HAp in simulated body fluid. The nano-porous HAp microspheres with an extensive surface and interconnecting pores thus demonstrate the potential of stimulating the formation of collagen and bone and the integration with the newly formed bones during physiological bone remodeling.

  18. Extension of the master sintering curve for constant heating rate modeling

    Science.gov (United States)

    McCoy, Tammy Michelle

    The purpose of this work is to extend the functionality of the Master Sintering Curve (MSC) such that it can be used as a practical tool for predicting sintering schemes that combine both a constant heating rate and an isothermal hold. Rather than just being able to predict a final density for the object of interest, the extension to the MSC will actually be able to model a sintering run from start to finish. Because the Johnson model does not incorporate this capability, the work presented is an extension of what has already been shown in literature to be a valuable resource in many sintering situations. A predicted sintering curve that incorporates a combination of constant heating rate and an isothermal hold is more indicative of what is found in real-life sintering operations. This research offers the possibility of predicting the sintering schedule for a material, thereby having advanced information about the extent of sintering, the time schedule for sintering, and the sintering temperature with a high degree of accuracy and repeatability. The research conducted in this thesis focuses on the development of a working model for predicting the sintering schedules of several stabilized zirconia powders having the compositions YSZ (HSY8), 10Sc1CeSZ, 10Sc1YSZ, and 11ScSZ1A. The compositions of the four powders are first verified using x-ray diffraction (XRD) and the particle size and surface area are verified using a particle size analyzer and BET analysis, respectively. The sintering studies were conducted on powder compacts using a double pushrod dilatometer. Density measurements are obtained both geometrically and using the Archimedes method. Each of the four powders is pressed into ¼" diameter pellets using a manual press with no additives, such as a binder or lubricant. Using a double push-rod dilatometer, shrinkage data for the pellets is obtained over several different heating rates. The shrinkage data is then converted to reflect the change in relative

  19. Sintering techniques for microstructure control in ceramics

    Science.gov (United States)

    Rosenberger, Andrew T.

    during sintering on microstructure and electronic properties of lithium aluminum titanium phosphate (LATP) electrolyte material was investigated by sintering LATP pellets under DC voltages of 0V, 2V, 10V, and 20V. Application of a DC voltage increased relative density from 86% to a maximum of 95.5%. However, unlike reports on other material systems such as zirconia, a high DC voltage induced, rather than restrained, abnormal grain growth. Conductivity decreased with applied voltage from 4.8*10 -4 S/cm at 0V to 1.3*10-4 S/cm at 20V, which was attributed to the high faceting and poor grain-to-grain contact of the grains sintered under 10V and 20V. This indicates that field-assisted sintering techniques may actually be detrimental to solid state battery materials, and that the field effects are significantly different from those observed in other systems in the literature.

  20. Processing of Polysulfone to Free Flowing Powder by Mechanical Milling and Spray Drying Techniques for Use in Selective Laser Sintering

    Directory of Open Access Journals (Sweden)

    Nicolas Mys

    2016-04-01

    Full Text Available Polysulfone (PSU has been processed into powder form by ball milling, rotor milling, and spray drying technique in an attempt to produce new materials for Selective Laser Sintering purposes. Both rotor milling and spray drying were adept to make spherical particles that can be used for this aim. Processing PSU pellets by rotor milling in a three-step process resulted in particles of 51.8 μm mean diameter, whereas spray drying could only manage a mean diameter of 26.1 μm. The resulting powders were characterized using Differential Scanning Calorimetry (DSC, Gel Permeation Chromatography (GPC and X-ray Diffraction measurements (XRD. DSC measurements revealed an influence of all processing techniques on the thermal behavior of the material. Glass transitions remained unaffected by spray drying and rotor milling, yet a clear shift was observed for ball milling, along with a large endothermic peak in the high temperature region. This was ascribed to the imparting of an orientation into the polymer chains due to the processing method and was confirmed by XRD measurements. Of all processed powder samples, the ball milled sample was unable to dissolve for GPC measurements, suggesting degradation by chain scission and subsequent crosslinking. Spray drying and rotor milling did not cause significant degradation.

  1. Manufacture, delivery and marketing of wood pellets

    International Nuclear Information System (INIS)

    Huhtanen, T.

    2001-01-01

    Wood pellet is a cheap fuel, the use of which can easily bee automated. Pellet heating can be carried out with a stoker or a pellet burner, which can be mounted to oil and solid fuels boiler or to solid fuel boilers. Vapo Oy delivers wood pellet to farms and detached houses via Agrimarket stores. Vapo Oy delivers pellets to large real estates, municipalities, industry, greenhouses and power plants directly as bulk. The pellets are delivered either by trailers or lorries equipped with fan-operated unloaders. The use of wood pellets is a suitable fuel especially for real estates, the boiler output of which is 20 - 1000 kW. Vapo Oy manufactures wood pellets of cutter chips, grinding dust and sawdust. The raw material for Ilomantsi pellet plant is purchased from the province of North Karelia. The capacity of pelletizing plant is 45 000 t of pellets per year, half of which is exported mainly to Sweden and Denmark

  2. Tritium pellet injector for TFTR

    International Nuclear Information System (INIS)

    Gouge, M.J.; Baylor, L.R.; Cole, M.J.; Combs, S.K.; Dyer, G.R.; Fehling, D.T.; Fisher, P.W.; Foust, C.R.; Langley, R.A.; Milora, S.L.; Qualls, A.L.; Wilgen, J.B.; Schmidt, G.L.; Barnes, G.W.; Persing, R.G.

    1992-01-01

    The tritium pellet injector (TPI) for the Tokamak Fusion Test Reactor (TFTR) will provide a tritium pellet fueling capability with pellet speeds in the 1- to 3-km/s range for the TFTR deuterium-tritium (D-T) phase. The existing TFTR deuterium pellet injector (DPI) has been modified at Oak Ridge National Laboratory (ORNL) to provide a four-shot, tritium-compatible, pipe-gun configuration with three upgraded single-stage pneumatic guns and a two-stage light gas gun driver. The TPI was designed to provide pellets ranging from 3.3 to 4.5 mm in diameter in arbitrarily programmable firing sequences at speeds up to approximately 1.5 km/s for the three single-stage drivers and 2.5 to 3 km/s for the two-stage driver. Injector operation is controlled by a programmable logic controller. The new pipe-gun injector assembly was installed in the modified DPI guard vacuum box, and modifications were made to the internals of the DPI vacuum injection line, including a new pellet diagnostics package. Assembly of these modified parts with existing DPI components was then completed, and the TPI was tested at ORNL with deuterium pellet. Results of the limited testing program at ORNL are described. The TPI is being installed on TFTR to support the D-D run period in 1992. In 1993, the tritium pellet injector will be retrofitted with a D-T fuel manifold and secondary tritium containment systems and integrated into TFTR tritium processing systems to provide full tritium pellet capability

  3. Use of chitosan-alginate as alternative pelletization aid to microcrystalline cellulose in extrusion/spheronization.

    Science.gov (United States)

    Charoenthai, Nattawut; Kleinebudde, Peter; Puttipipatkhachorn, Satit

    2007-09-01

    Two types of different molecular weight chitosan were investigated as a pelletization aid in extrusion/spheronization using water as granulation liquid. Spherical pellets with a maximum fraction of 60% w/w chitosan could be produced when 1.25-2.5% w/w sodium alginate was included in the formulations with no microcrystalline cellulose (MCC). Chitosan with lower molecular weight of 190 kDa showed a better pellet forming property. The pellets obtained had acceptable physical characteristics and a fast drug release. The results from Fourier transform infrared spectroscopy, differential scanning calorimetry and (13)C CP-MAS nuclear magnetic resonance spectroscopy confirmed the formation of polyelectrolyte complex (PEC) between chitosan and sodium alginate, which might be a reason for successful pelletization by extrusion/spheronization. Moreover, the presence of PEC might influence the physical characteristics and dissolution behavior of chitosan-alginate pellets. The results indicated an achievement in production of pellets by extrusion/spheronization without using MCC. Moreover, chitosan combined with sodium alginate could be used as a promising alternative pelletization aid to MCC in extrusion/spheronization. (c) 2007 Wiley-Liss, Inc. and the American Pharmacists Association.

  4. Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by Selective Laser Melting of Powder Produced by Granulation-Sintering-Deoxygenation Method

    Science.gov (United States)

    Sun, Pei; Fang, Z. Zak; Zhang, Ying; Xia, Yang

    2017-12-01

    Commercial spherical Ti powders for additive manufacturing applications are produced today by melt-atomization methods at relatively high costs. A meltless production method, called granulation-sintering-deoxygenation (GSD), was developed recently to produce spherical Ti alloy powder at a significantly reduced cost. In this new process, fine hydrogenated Ti particles are agglomerated to form spherical granules, which are then sintered to dense spherical particles. After sintering, the solid fully dense spherical Ti alloy particles are deoxygenated using novel low-temperature deoxygenation processes with either Mg or Ca. This technical communication presents results of 3D printing using GSD powder and the selective laser melting (SLM) technique. The results showed that tensile properties of parts fabricated from spherical GSD Ti-6Al-4V powder by SLM are comparable with typical mill-annealed Ti-6Al-4V. The characteristics of 3D printed Ti-6Al-4V from GSD powder are also compared with that of commercial materials.

  5. Linear resonance acceleration of pellets

    International Nuclear Information System (INIS)

    Mills, R.G.

    1978-01-01

    A possible requirement for the acceleration of macroscopic pellets to velocities exceeding 10 4 meters per second implies the development of new apparatus. A satisfactory approach might be the linear resonance accelerator. Such apparatus would require the charging of pellets to very high values not yet demonstrated. The incompatibility of phase stability with radial stability in these machines may require abandoning phase stability and adopting feedback control of the accelerating voltage to accommodate statistical fluctuations in the charge to mass ratio of successive pellets

  6. Spark plasma sintering and porosity studies of uranium nitride

    Science.gov (United States)

    Johnson, Kyle D.; Wallenius, Janne; Jolkkonen, Mikael; Claisse, Antoine

    2016-05-01

    In this study, a number of samples of UN sintered by the SPS method have been fabricated, and highly pure samples ranging in density from 68% to 99.8%TD - corresponding to an absolute density of 14.25 g/cm3 out of a theoretical density of 14.28 g/cm3 - have been fabricated. By careful adjustment of the sintering parameters of temperature and applied pressure, the production of pellets of specific porosity may now be achieved between these ranges. The pore closure behaviour of the material has also been documented and compared to previous studies of similar materials, which demonstrates that full pore closure using these methods occurs near 97.5% of relative density.

  7. Formulation and Evaluation of Olanzapine Matrix Pellets for Controlled Release

    Directory of Open Access Journals (Sweden)

    S Mohammed Khan

    2011-10-01

    Full Text Available "nBackground and the purpose of the study: Olanzapine is an antipsychotic used in treatment of schizophrenia. This research was carried out to design oral controlled release matrix pellets of water insoluble drug Olanzapine (OZ, using blend of Sodium Alginate (SA and Glyceryl Palmito-Stearate (GPS as matrix polymers, micro crystalline cellulose (MCC as spheronizer enhancer and Sodium Lauryl Sulphate (SLS as pore forming agent. Olanzapine is an antipsychotic used in treatment of   schizophrenia. This research was carried out to design oral controlled release matrix pellets of water insoluble drug Olanzapine (OZ, using blend of Sodium Alginate (SA and Glyceryl Palmito-Stearate (GPS as matrix polymers, micro crystalline cellulose (MCC as spheronizer enhancer and Sodium Lauryl Sulphate (SLS as pore forming agent. "nMethods: OZ formulations were developed by the pelletization technique by drug loaded pellets and characterized with regard to the drug content, size distribution, Scanning Electron Microscopy (SEM, Differential Scanning Calorimetry (DSC, Fourier Transform Infrared Spectroscopy (FTIR and X-ray Diffraction study (XRD. Stability studies were carried out on the optimized formulation for a period of 90 days at 40 ± 2 °C and 75 ± 5% relative humidity. Results and major conclusion: The drug content was in the range of 93.34-98.12 %. The mean particle size of the drug loaded pellets was in the range 1024 to 1087μm. SEM photographs and calculated sphericity factor confirmed that the prepared formulations were spherical in nature. The compatibility between drug and polymers in the drug loaded pellets was confirmed by DSC and FTIR studies. Stability studies indicated that pellets are stable. XRD patterns revealed the crystalline nature of the pure OZ. Loose surface crystal study indicated that crystalline OZ is present in all formulations and more clear in formulation F5. Drug release was controlled for more than 24 hrs and mechanism of the

  8. Hygroscopicity of Wood Pellets. Test method development - Influence on pellet quality - Coating of wood Pellets

    Energy Technology Data Exchange (ETDEWEB)

    Greinoecker, Christa; Pichler, Wilfried; Golser, Michael [Holzforschung Austria (HFA), Vienna (Austria)

    2006-07-15

    One target of a four year R and D pellet project at Holzforschung Austria was to safeguard the quality of wood Pellets during storage, with particular attention to abrasion and water content. Therefore, a testing method was developed and the absorption of water analysed under defined conditions. The results showed that the water content of Pellets stored in climatic conditions above 70 % relative humidity and a temperature of 20 deg C starts to cross the normative threshold according to OeNORM M 7135 and DINplus of 10 % (wet base). Above this threshold value, the abrasion of wood Pellets rose exponentially, whereas Pellets with an initial low water content had the highest abrasion in the end. Thus a further challenge was to look for methods to minimise the water absorption during storage. Coating is part of the fodder pelletising process but is not currently used in the wood pelletising process. Coating Pellets with a kind of hydrophobic substance was considered. Experiments with oil and paraffin-dipped Pellets caused low water absorption, but in consideration of the financial input, the sensoric and ecologic losses, it is not reasonable to use it.

  9. High-level radioactive waste fixation in sintered vitreous matrix

    International Nuclear Information System (INIS)

    Russo, D.O.; Messi de Bernasconi, N.; Audero, M.A.

    1987-01-01

    The safe storage of high-level wastes from fuel elements reprocessing includes, as a first step, the fixation of the same in materials having a good resistance to the leaching in aqueous medium, such as borosilicate glass. As an alternative to the usual method of the molten glasses, a procedure for the sintering of a powdered glass and waste mixture at lower temperatures (600-700 deg C) has been developed, which minimizes the volatilization of active compounds during the process. Two glasses matrices of different composition and characteristics were used, to which the simulated wastes were added in the ratio of a 10% in weight of oxides. Two sintering techniques were employed 1: cold pressing and further sintering; 2: hot pressing and sintering under pressure. The densities were measured, the microstructure of the samples was analyzed and leaching essays were made in distilled water. The pellet's microstructure was observed by means of optical microscopy, by reflection in polished samples and by transparency in thin slices. The presence of crystalline compounds was analyzed by means of x rays and electron microprobe. The results have shown the convenience to continue with hot pressing essays, because a denser product with a higher resistance to the leaching is thus obtained. (M.E.L.) [es

  10. Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

    International Nuclear Information System (INIS)

    Butt, Drryl P.; Jaques, Brian

    2009-01-01

    Research conducted for this NERI project has advanced the understanding and feasibility of nitride nuclear fuel processing. In order to perform this research, necessary laboratory infrastructure was developed; including basic facilities and experimental equipment. Notable accomplishments from this project include: the synthesis of uranium, dysprosium, and cerium nitrides using a novel, low-cost mechanical method at room temperature; the synthesis of phase pure UN, DyN, and CeN using thermal methods; and the sintering of UN and (U x , Dy 1-x )N (0.7 (le) X (le) 1) pellets from phase pure powder that was synthesized in the Advanced Materials Laboratory at Boise State University.

  11. Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Drryl P. Butt; Brian Jaques

    2009-03-31

    Research conducted for this NERI project has advanced the understanding and feasibility of nitride nuclear fuel processing. In order to perform this research, necessary laboratory infrastructure was developed; including basic facilities and experimental equipment. Notable accomplishments from this project include: the synthesis of uranium, dysprosium, and cerium nitrides using a novel, low-cost mechanical method at room temperature; the synthesis of phase pure UN, DyN, and CeN using thermal methods; and the sintering of UN and (Ux, Dy1-x)N (0.7 ≤ X ≤ 1) pellets from phase pure powder that was synthesized in the Advanced Materials Laboratory at Boise State University.

  12. Direct pelletization in a rotary processor controlled by torque measurements. III. Investigation of microcrystalline cellulose and lactose grade.

    Science.gov (United States)

    Kristensen, Jakob

    2005-10-24

    The aim of the present study was to investigate the use of different grades of microcrystalline cellulose (MCC) and lactose in a direct pelletization process in a rotary processor. For this purpose, a mixed 2- and 3-level factorial study was performed to determine the influence of the particle size of microcrystalline cellulose (MCC) (approximately 60 and 105 microm) and lactose (approximately 30, 40, and 55 microm), as well as MCC type (Avicel and Emcocel) on the pelletization process and the physical properties of the prepared pellets. A 1:4 mixture of MCC and lactose was applied, and granulation liquid was added until a 0.45 Nm increase in the torque of the friction plate was reached. All combinations of the 3 factors resulted in spherical pellets of a high physical strength. The particle size of MCC was found to have no marked effect on the amount of water required for agglomerate growth or on the size of the resulting pellets. An increasing particle size of lactose gave rise to more spherical pellets of a more narrow size distribution as well as higher yields. The MCC type was found to affect both the release of the model drug from the prepared pellets and the size distribution. Generally, the determined influence of the investigated factors was small, and direct pelletization in a rotary processor was found to be a robust process, insensitive to variations in the particle size and type of MCC and the particle size of lactose.

  13. Analysis of pharmaceutical pellets: An approach using near-infrared chemical imaging

    International Nuclear Information System (INIS)

    Sabin, Guilherme P.; Breitkreitz, Marcia C.; Souza, Andre M. de; Fonseca, Patricia da; Calefe, Lupercio; Moffa, Mario; Poppi, Ronei J.

    2011-01-01

    Highlights: → Near-Infrared Chemical Imaging was used for pellets analysis. → Distribution of the components throughout the coatings layers and core of the pellets was estimated. → Classical Least Squares (CLS) was used for calculation of the concentration maps. - Abstract: Pharmaceutical pellets are spherical or nearly spherical multi-unit dosage forms designed to optimize pharmacokinetics and pharmacodynamics features of drug release. The distribution of the pharmaceutical ingredients in the layers and core is a very important parameter for appropriate drug release, especially for pellets manufactured by the process of layer gain. Physical aspects of the sample are normally evaluated by Scanning Electron Microscopy (SEM), but it is in many cases unsuitable to provide conclusive chemical information about the distribution of the pharmaceutical ingredients in both layers and core. On the other hand, methods based on spectroscopic imaging can be very promising for this purpose. In this work, a Near-Infrared Chemical Imaging (NIR-CI) method was developed and applied to the analysis of diclophenac sodium pellets. Since all the compounds present in the sample were known in advance, Classical Least Squares (CLS) was used for calculations. The results have shown that the method was capable of providing chemical information about the distribution of the active ingredient and excipients in the core and coating layers and therefore can be complementary to SEM for the pharmaceutical development of pellets.

  14. Analysis of pharmaceutical pellets: An approach using near-infrared chemical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sabin, Guilherme P.; Breitkreitz, Marcia C.; Souza, Andre M. de [Institute of Chemistry, University of Campinas, P.O. Box 6154, 13084-971 Campinas, SP (Brazil); Fonseca, Patricia da; Calefe, Lupercio; Moffa, Mario [Zelus Servicos para Industria Farmaceutica Ltda., Av. Professor Lineu Prestes n. 2242, Sao Paulo, SP (Brazil); Poppi, Ronei J., E-mail: ronei@iqm.unicamp.br [Institute of Chemistry, University of Campinas, P.O. Box 6154, 13084-971 Campinas, SP (Brazil)

    2011-11-07

    Highlights: {yields} Near-Infrared Chemical Imaging was used for pellets analysis. {yields} Distribution of the components throughout the coatings layers and core of the pellets was estimated. {yields} Classical Least Squares (CLS) was used for calculation of the concentration maps. - Abstract: Pharmaceutical pellets are spherical or nearly spherical multi-unit dosage forms designed to optimize pharmacokinetics and pharmacodynamics features of drug release. The distribution of the pharmaceutical ingredients in the layers and core is a very important parameter for appropriate drug release, especially for pellets manufactured by the process of layer gain. Physical aspects of the sample are normally evaluated by Scanning Electron Microscopy (SEM), but it is in many cases unsuitable to provide conclusive chemical information about the distribution of the pharmaceutical ingredients in both layers and core. On the other hand, methods based on spectroscopic imaging can be very promising for this purpose. In this work, a Near-Infrared Chemical Imaging (NIR-CI) method was developed and applied to the analysis of diclophenac sodium pellets. Since all the compounds present in the sample were known in advance, Classical Least Squares (CLS) was used for calculations. The results have shown that the method was capable of providing chemical information about the distribution of the active ingredient and excipients in the core and coating layers and therefore can be complementary to SEM for the pharmaceutical development of pellets.

  15. Handling of Deuterium Pellets for Plasma Refuelling

    DEFF Research Database (Denmark)

    Jensen, Peter Bjødstrup; Andersen, Verner

    1982-01-01

    The use of a guide tube technique to inject pellets in pellet-plasma experiments is described. The effect of the guide tube on the mass and speed of a slowly moving pellet ( nu approximately 150 m s-1) is negligible. To improve the divergence in trajectories of the pellets on leaving the guide tube...

  16. The UO2 pellets plant experimental background of the established process

    International Nuclear Information System (INIS)

    Aparicio Arroyo, E.; Alonso Folgueras, J. A.

    1969-01-01

    An account of the UO 2 research and development carried out at the JEN is first given. This includes a 10 tons/year pellet Plant construction. Experimental background of the process is established, pointing out both milling advantages and risks, granulation devices, automatic press selection, binder removing and sintering furnaces. Origin, surface area, grain size and 0/U rate are considered as raw material reception parameters, although this process shows a wide scope. (Author) 13 refs

  17. North America's wood pellet sector

    Science.gov (United States)

    Henry Spelter; Daniel Toth

    2009-01-01

    The North American wood pellet sector is profiled in this paper. A small pellet industry has existed since the 1930s, but its main growth occurred in the wake of the energy crisis in the 1970s. Its current spurt is even greater, growing from is set to reach 6.2 million in 2009. Most plants are small, relying on sawmill residues for fiber and thus are limited to 100,000...

  18. Centrifuge pellet injector for JET

    International Nuclear Information System (INIS)

    Andelfinger, C.; Buchelt, E.; Jacobi, D.; Lackner, E.; Schilling, H.B.; Ulrich, M.; Weber, G.

    1983-08-01

    An engineering design of a centrifuge pellet injector for JET is reported as part of the Phase I contract number JE 2/9016. A rather detailed design is presented for the mechanical and electronic features. Stress calculations, dynamic behaviour and life estimates are considered. The interfaces to the JET vacuum system and CODAS are discussed. Proposals for the pellet diagnostics (velocity, mass and shape) are presented. (orig.)

  19. Solid deuterium centrifuge pellet injector

    International Nuclear Information System (INIS)

    Foster, C.A.

    1982-01-01

    Pellet injectors are needed to fuel long pulse tokamak plasmas and other magnetic confinement devices. For this purpose, an apparatus has been developed that forms 1.3-mm-diam pellets of frozen deuterium at a rate of 40 pellets per second and accelerates them to a speed of 1 km/s. Pellets are formed by extruding a billet of solidified deuterium through a 1.3-mm-diam nozzle at a speed of 5 cm/s. The extruding deuterium is chopped with a razor knife, forming 1.3-mm right circular cylinders of solid deuterium. The pellets are accelerated by synchronously injecting them into a high speed rotating arbor containing a guide track, which carries them from a point near the center of rotation to the periphery. The pellets leave the wheel after 150 0 of rotation at double the tip speed. The centrifuge is formed in the shape of a centrifugal catenary and is constructed of high strength KEVLAR/epoxy composite. This arbon has been spin-tested to a tip speed of 1 km/s

  20. 46 CFR 148.04-21 - Coconut meal pellets (also known as copra pellets).

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Coconut meal pellets (also known as copra pellets). 148.04-21 Section 148.04-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS... § 148.04-21 Coconut meal pellets (also known as copra pellets). (a) Coconut meal pellets; (1) Must...

  1. Sintering of B4C by pressureless liquid phase sintering

    International Nuclear Information System (INIS)

    Rocha, Rosa Maria da; Melo, Francisco Cristovao Lourenco de

    2009-01-01

    The effect of three different sintering additive systems on densification of boron carbide powder was investigated. The sintering additives were Al 2 O 3 :Y 2 O 3 , AlN:Y 2 O 3 and BN:Y 2 O 3 compositions. Powder mixtures were prepared with 10 vol% of sintering aids following conventional powder technology processes. Samples were sintered by pressureless sintering at 2050 deg C/30min in argon atmosphere. Sintered samples were compared to a sintered B 4 C without sintering additive. Samples were characterized by XRD to analyze the crystalline phases after sintering and SEM to observe the microstructure and the second phase distribution. YB 4 and YB 2 C 2 were identified in all samples, indicating a reaction between Y 2 O 3 , B 4 C and B 2 O 3 present at the B 4 C particle surface. The best densification result was achieved with Al 2 O 3 :Y 2 O 3 additive system, showing 92.0 % of theoretical density, low porosity and 15.2 % of linear shrinkage. But this sample showed the highest weight loss. (author)

  2. Model for the behaviour of thorium and uranium fuels at pelletization

    International Nuclear Information System (INIS)

    Ferreira Neto, Ricardo Alberto

    2000-11-01

    In this work, a model for the behaviour of thorium-uranium-mixed oxide microspheres in the pelletizing process is presented. This model was developed in a program whose objective was to demonstrate the viability of producing fissile material through the utilization of thorium in pressurized water reactors. This is important because it allows the saving of the strategic uranium reserves, and makes it possible the nuclear utilization of the large brazilian thorium reserves. The objective was to develop a model for optimizing physical properties of the microspheres, such as density, fracture strength and specific surface, so as to produce fuel pellets with microstructure, density, open porosity and impurity content, in accordance with the fuel specification. And, therefore, to adjust the sol-gel processing parameters in order to obtain these properties, and produce pellets with an optimized microstructure, adequate to a stable behaviour under irradiation. The model made it clear that to achieve this objective, it is necessary to produce microspheres with density and specific surface as small as possible. By changing the sol-gel processing parameters, microspheres with the desired properties were produced, and the model was experimentally verified by manufacturing fuel pellets with optimized microstructures, density, open porosity and impurity content, meeting the specifications for this new nuclear fuel for pressurized water reactors. Furthermore it was possible to obtain mathematical expressions that enables to calculate from the microspheres properties and the utilized compaction pressure, the sinter density that will be obtained in the sintered pellet and the necessary compaction pressure to reach the sintered density specified for the fuel. (author)

  3. Development of import subtituting technologies for increasing productivity of sintering machines and strength of agglomerates

    Directory of Open Access Journals (Sweden)

    В. Л. Трушко

    2016-11-01

    Full Text Available A problem of industrial fluxed agglomerates self-destruction in the process of cooling after sintering has been examined. It has been revealed that the main reason of strength degradation is polymorphism of dicalcium silicate Ca2SiO4 (or short designation С2S: β-Ca2SiO4 ® γ-Ca2SiO4. Ways for increasing the  agglomerate  strength by physical and crystal-chemical stabilization of the high temperature modification of C2S have been proposed and tested. Physical stabilization of C2S agglomerate is increased with its structure reinforcement due to thickening of walls between large pores that is achieved by increasing height of the sintered layer through improvement of its gas permeability. The task is addressed by substituting the previously used import sintering ore with the  polydisperse ore from the Yakovlevo field, which improves the charge  pelletizing by 3-4 times and helps to bring the  height of the sintered layer and the strength of the domestic agglomerate up to the international best practice standards, while eliminating a need to purchase import high-vacuum   exhausters. In practice crystal-chemical stabilization of C2S within iron-ore  agglomerate is ensured by adding an  opti- mal multicomponent additive in the form of the    waste product  generated in production  of alumina  from bauxites, i.e. the red mud, to the initial sinter charge. Thus mechanical strength of agglomerates and pellets is increased by 5-10 % and their hot strength improves by 20-40 %. The productivity of sintering machines and blast furnaces improves by 5-10 %. Specific coke consumption reduces by 2-2.5 %. In production of iron-ore pellets red mud is substituting the import  bentonite.

  4. Fabrication of DUPIC fuel pellets using high burn-up spent PWR fuel

    International Nuclear Information System (INIS)

    Lee, Jung-Won; Park, Geun-Il; Choi, Yong

    2012-01-01

    Technology for the direct usage of a spent PWR fuel in CANDU reactors (DUPIC) was developed in KAERI to reduce the amount of spent fuel. DUPIC fuel pellets were fabricated using a dry processing method to re-fabricate CANDU fuel from spent PWR fuel without any intentional separation of fissile materials or fission products. The DUPIC fuel element fabrication process satisfied a quality assurance program in accordance with the Canadian standard. For the DUPIC fuels with various fuel burn-ups between 27,300 and 65,000 MWd/tU, the sintered pellet density decreased with increasing fuel burn-ups. Fission gas releases and powder properties of the spent fuel also influenced the DUPIC fuel characteristics. Measurement of cesium content released from green pellets revealed that their sintered density significantly depended on sintering temperature history. It was useful to establish a DUPIC fuel fabrication technology in which a high-burn-up fuel with 65,000 MWd/tU was treated. (author)

  5. Sintering kinetics in (Th, 5%U)O2 in the initial stage

    International Nuclear Information System (INIS)

    Ferraz, W.B.; Cardoso, P.E.; Lameiras, F.S.

    1990-01-01

    The initial sintering kinetics of (Th,5%U)O 2 pellets, in air and Ar-4%H 2 atmosphere in the temperature range 950-1175 0 C, was examined by dilatometric analysis. It was observed that the sintering in air occurs at a lower temperature. Based on Johnson's model, the volume diffusion and the grain boundary diffusion were assumed to cause the linear shrinkage. From the general equation of this model Δl/l=kt n the values n approx. 0,49 and n≥ 0,33, for sintering in air and Ar-4%H 2 atmosphere respectively, were observed. These results revealed that the initial sintering kinetics in air is controlled by volume diffusion and in Ar-4%H 2 atmosphere is weakly predominated by the grain boundary diffusion. The estimated volumetric diffusion coefficient for the sintering in air is about three orders of magnitude greater than in Ar-4%H 2 atmosphere, indicating a strong influence of the stoichiometrie on the sintering kinetics. The grain boundary diffusion coefficient appears to be independent of the sintering atmosphere. (author) [pt

  6. Development of AUC-based process at BARC for production of free-flowing and sinterable UO2 powder

    International Nuclear Information System (INIS)

    Keni, V.S.; Ghosh, S.K.; Ganguly, C.; Majumdar, S.

    1994-01-01

    Ammonium uranium carbonate (AUC) process has been developed and industrially used in Germany for preparation of free-flowing and sinterable UO 2 powder for fabrication of UO 2 fuel pellets for light water reactors (LWR). Efforts are underway at Bhabha Atomic Research Centre (BARC) for developing AUC-based process which would yield free-flowing UO 2 powder suitable for direct pelletisation and sintering to very high density (> 96% T.D.) UO 2 fuel pellets for pressurised heavy water reactors (PHWRs) in India. The first phase of this work has been completed jointly by Chemical Engineering Division (ChED) and Radiometallurgy Division (RMD) in batches of 1.5 kg. It was possible to fabricate UO 2 pellets of density 93-95% T.D. on a reproducible basis. At ChED, process parameters have been optimised for fabrication of AUC with suitable physical properties in batches of 1.5 kg (U), starting with nuclear pure uranyl nitrate solution. At RMD calcination parameters of AUC was optimised in batches of 500 g for obtaining free-flowing UO 2 powder, suitable for direct pelletisation and sintering. The pelletisation and sintering have been carried out at Radiometallurgy Division in batches of 1-1.5 kg. The maximum achievable density of UO 2 pellets has been in the range of 95.5-96% T.D. (author). 11 refs

  7. Enhanced Thermal Conductivities of ZrO2 Pellets Reinforced with Mo Wires or Powder

    International Nuclear Information System (INIS)

    Kim, Joon Hui; Hong, Soon H; Ryu, Ho Jin

    2014-01-01

    Considering the reported results, a promising concept for increasing the thermal conductivity of UO 2 is proposed by employing 2D or 3D networks of thermally conducting phases inside the oxide pellets. But there is not enough systematic results using high thermal conductivity 2D or 3D network structures.. Theoretically high porosity metal foams and nanowire networks can be used as the 3D network preforms in the powder processing of UO 2 -based composite pellets. ZrO 2 which has a thermal conductivity as low as UO 2 is used for the experiment while its chemical and microstructural evolution might be different from those of UO 2 . And since UO 2 pellets are fabricated at high temperatures above 1700 .deg. C, the first requirement for the reinforcement network metal should be the high temperature stability. Among the refractory metals, Mo has significantly high thermal conductivity (138 W/mK). In order to increase the thermal conductivity of ZrO 2 , which is used for a surrogate material for UO 2 fuel, ZrO 2 composite pellets with the addition of Mo mesh, Mo fiber and Mo powder were fabricated by spark plasma sintering.. Thermal conductivity measurement results of composite pellets showed that adding 2D network Mo mesh, 3D network Mo mesh and Mo powder increased thermal conductivity of ZrO 2 composite pellets. But with the same volume percent of Mo, 3D network of Mo mesh showed the best result

  8. New composite separator pellet to increase power density and reduce size of thermal batteries

    Energy Technology Data Exchange (ETDEWEB)

    Mondy, Lisa Ann [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roberts, Christine Cardinal [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grillet, Anne Mary [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soehnel, Melissa Marie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barringer, David Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); DiAntonio, Christopher Brian [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chavez, Thomas P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Ingersoll, David T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hughes, Lindsey Gloe [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Evans, Lindsey R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Fitchett, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-11-01

    We show that it is possible to manufacture strong macroporous ceramic films that can be backfilled with electrolyte to form rigid separator pellets suitable for use in thermal batteries. Several new ceramic manufacturing processes are developed to produce sintered magnesium oxide foams with connected porosities of over 80% by volume and with sufficient strength to withstand the battery manufacturing steps. The effects of processing parameters are quantified, and methods to imbibe electrolyte into the ceramic scaffold demonstrated. Preliminary single cell battery testing show that some of our first generation pellets exhibit longer voltage life with comparable resistance at the critical early times to that exhibited by a traditional pressed pellets. Although more development work is needed to optimize the processes to create these rigid separator pellets, the results indicate the potential of such ceramic separator pellets to be equal, if not superior to, current pressed pellets. Furthermore, they could be a replacement for critical material that is no longer available, as well as improving battery separator strength, decreasing production costs, and leading to shorter battery stacks for long-life batteries.

  9. Effects of calcium hydroxide and calcium chloride addition to bentonite in iron ore pelletization.

    Science.gov (United States)

    Tugrul, Nurcan; Derun, Emek Moroydor; Pişkin, Mehmet

    2006-10-01

    Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder.

  10. Sintering mechanisms of SnO2 compacts doped with Nb2O5

    International Nuclear Information System (INIS)

    Gouvea, D.; Santilli, C.V.; Varela, J.A.

    1990-01-01

    Grain and pore growth are observed during sintering of SnO 2 without any densification for temperature up to 1500 0 C. This behaviour is due to mass transport through vapor phase. In order to favor densifying mechanism several concentrations of Nb 2 O 5 were added to SnO 2 (1.0, 3.0, 5.0 and 10.0 mol%). Sintering of Nb 2 O 5 doped SnO 2 pellets in the range of 1000 to 1450 0 C indicate that Nb 2 O 5 inhibits SnO 2 evaporation allowing some densification at 1450 0 C. (author) [pt

  11. Dry recovery test of plutonium-uranium mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    Kinugasa, Manabu; Kawamata, Kazuhiko; Kashima, Sadamitsu

    1981-01-01

    The oxidation conditions for pulverizing directly Pu-U mixed oxide pellets without mechanical crushing were examined to simplify the process and to reduce radiation exposure during the dry recovery of highly enriched Pu pellets. The specimens used were the Pusub(0.3) Usub(0.7) Osub(2-x) pellets with different density, which were sintered at 1650 deg C for 2 hours under an atmosphere of 5 % H 2 - N 2 . The oxidation experiment was carried out under several conditions. The oxidation products were examined by weight gain, X-ray diffraction, appearance pictures, SEM photographs and so on. From these studies, it can be concluded that the oxidation in NO 2 diluted with air was very powerful, but if only the coarse spalling of Pusub(0.3) Usub(0.7) O 2 sintered pellets is required, it is sufficient to oxidize them in air for 1 hr in a temperature range from 400 to 600 deg C. (Asami, T.)

  12. Boric oxide or boric acid sintering aid for sintering ceramics

    International Nuclear Information System (INIS)

    Lawler, H.A.

    1979-01-01

    The invention described relates to the use of liquid sintering aid in processes involving sintering of ceramic materials to produce dense, hard articles having industrial uses. Although the invention is specifically discussed in regard to compositions containing silicon carbide as the ceramic material, other sinterable carbides, for example, titanium carbide, may be utilized as the ceramic material. A liquid sintering aid for densifying ceramic material is selected from solutions of H 3 BO 3 , B 2 O 3 and mixtures of these solutions. In sintering ceramic articles, e.g. silicon carbide, a shaped green body is formed from a particulate ceramic material and a resin binder, and the green body is baked at a temperature of 500 to 1000 0 C to form a porous body. The liquid sintering aid of B 2 O 3 and/or H 3 BO 3 is then dispersed through the porous body and the treated body is sintered at a temperature of 1900 to 2200 0 C to produce the sintered ceramic article. (U.K.)

  13. Sintering of magnesia: effect of additives

    Indian Academy of Sciences (India)

    % was studied on the sinter- ing and microstructural developments of the chemically pure magnesia using the pressureless sintering technique between 1500 and 1600◦C. Sintering was evaluated by per cent densification and microstructural ...

  14. Study of the oxidation risks during the sintering of uranium dioxide, and characterization of the excess oxygen

    International Nuclear Information System (INIS)

    Conte, M.; Brandela, M.

    1966-05-01

    During sintering in reducing atmospheres, UO 2 pellets can be oxidized by gaseous impurities. The effects of temperature cycles, the partial pressure of O 2 and the flow rate of the gas over the pellets were investigated. In these atmospheres, the O 2 partial pressure during sintering is low at high temperatures, as a consequence of the dissociation rate of the combined water, but below 1000 deg C, it can be high enough to result in a noticeable oxidation of the surface of the pellets during cooling. The crystalline phases which can occur have been identified and two methods of detection have been proposed: a micrographic examination after chemical etching and radiocrystallography. (authors) [fr

  15. Microencapsulation and fabrication of fuel pellets for inertial confinement fusion

    International Nuclear Information System (INIS)

    Nolen, R.L. Jr.; Kool, L.B.

    1981-01-01

    Various microencapsulation techniques were evaluated for fabrication of thermonuclear fuel pellets for use in existing experimental facilities studying inertial confinement fusion and in future fusion-power reactors. Coacervation, spray drying, in situ polymerization, and physical microencapsulation methods were employed. Highly spherical, hollow polymeric shells were fabricated ranging in size from 20 to 7000 micron. In situ polymerization microencapsulation with poly(methyl methacrylate) provided large shells, but problems with local wall defects still must be solved. Extension to other polymeric systems met with limited success. Requirements for inertial confinement fusion targets are described, as are the methods that were used

  16. Hot impact densification (HID) - a new method of producing ceramic nuclear fuel pellets with tight dimensional tolerances

    Energy Technology Data Exchange (ETDEWEB)

    Hrovat, M.; Rachor, L. (Nuklear-EEhemie und -Metallurgie G.m.b.H. (NUKEM), Hanau (Germany, F.R.)); Muehling, G. (Kernforschungszentrum Karlsruhe G.m.b.H. (Germany, F.R.). Projekt Schneller Brueter); Vollath, D.; Zimmermann, H. (Kernforschungszentrum Karlsruhe G.m.b.H. (Germany, F.R.). Inst. fuer Material- und Festkoerperforschung)

    1984-05-01

    The hot impact densification (HID) is a new powerful method for producing ceramic fuel pellets for nuclear reactors. Green ceramic bodies are directly processed to pellets by high speed shaping in the plastic temperature region of ceramic material. Opposed to the well established press sintering procedure it can be heated, densified, and cooled by orders of magnitude faster. Therefore, at high throughputs, small equipment dimensions become possible. The fuel pellets produced meet all requirements, particular the dimensional tolerances achieved are very close, consequently circular grinding is omitted. Furthermore, the relatively high temperature level of the impact pressing favors the mixed crystal formation of uranium and plutonium oxide. This improves the solubility of the fuel in nitric acid, an essential point at reprocessing. A prototype facility is designed so that automatic fabrication in continuous operation will be possible. The target working cycle for a fuel pellet is in the range of some seconds.

  17. Study of the sintering process and the formation of a (Th, U) O2 solid solution

    International Nuclear Information System (INIS)

    Tomasi, Roberto

    1979-01-01

    The effect of some variables in the (Th, U) O 2 sintering process and solid solution formation was studied. ThO 2 , U 3 O 8 and UO 2 powder were prepared. The ThO 2 powders were obtained by calcination of thorium at 500 and 750 deg C; the U 3 O 8 powders were derived from the calcination of ADU at 660 and 750 deg C; the UO 2 powder were prepared from ADU and from ATCU. The different characteristics of these materials were determined by measurements of surface area, by scanning electron microscopy, tap density tests, X-ray diffractometry and by measurements of the O/U ratios. The oxide mixtures were chosen in order to produce a final composition with 10 w/o of UO 2 . A mixture of thorium oxalate and ADU was also prepared by calcining these salts in air at 700 deg C, in order to obtain certain amount of solid solution prior to sintering. The sintering operations were developed in an argon atmosphere at temperatures between 1400 and 1700 deg C, during interval varying from 1 to 4 hours. The effect of the mixture characteristics on the sintering process and solid solution formation were studied considering the results of densification, microstructure development and X-ray diffractometry. The ThO 2 powder characteristics have a main effect on the mixtures compactability and sinterability, the higher calcining temperatures increasing the green density, but decreasing the final density of the sintered pellets. In the sintering of mixtures containing U 3 O 3 , this oxide is reduced to UO 2 and it is possible to obtain pellets with density and microstructures similar to those produced from mixtures containing UO 2 . But if oxygen in excess is present during sintering, the process is affected, occurring exaggerated grain growth. The densification results were related to the Coble's kinetics equation for second stage of sintering, valid for bulk diffusion, grain boundary acting as vacancy sinks. The sintering activation energy is independent from the powder starting

  18. A mathematical model to predict the size of the pellets formed in freeze pelletization techniques: parameters affecting pellet size.

    Science.gov (United States)

    Cheboyina, Sreekhar; O'Haver, John; Wyandt, Christy M

    2006-01-01

    A mathematical model was developed based on the theory of drop formation to predict the size of the pellets formed in the freeze pelletization process. Further the model was validated by studying the effect of various parameters on the pellet size such as viscosity of the pellet forming and column liquids, surface/interfacial tension, density difference between pellet forming and column liquids; size, shape, and material of construction of the needle tips and temperatures maintained in the columns. In this study, pellets were prepared from different matrices including polyethylene glycols and waxes. The column liquids studied were silicone oils and aqueous glycerol solutions. The surface/interfacial tension, density difference between pellet forming and column liquids and needle tip size were found to be the most important factors affecting pellet size. The viscosity of the column liquid was not found to significantly affect the size of the pellets. The size of the pellets was also not affected by the pellet forming liquids of low viscosities. An increase in the initial column temperature slightly decreased the pellet size. The mathematical model developed was found to successfully predict the size of the pellets with an average error of 3.32% for different matrices that were studied.

  19. Co-injection of basic fluxes or BF flue dust with PC into a BF charged with 100% pellets:effects on slag formation and coal combustion

    OpenAIRE

    Sundqvist Ökvist, Lena

    2004-01-01

    Based on 100% pellets operation at BF No. 3 at SSAB Tunnplåt in Luleå a new pellet with CaO/SiO2=1 was developed during early nineties. The pellet showed good results in metallurgical laboratory test but caused slag formation problems in the bosh. A high basicity slag was formed during interaction with basic fluxes and its melting point was increased when the slag was finally reduced. By injection of basic fluxes, the slag formation problems in the bosh can be avoided. Without a sinter plant,...

  20. Laser sintering of copper nanoparticles

    International Nuclear Information System (INIS)

    Zenou, Michael; Saar, Amir; Ermak, Oleg; Kotler, Zvi

    2014-01-01

    Copper nanoparticle (NP) inks serve as an attractive potential replacement to silver NP inks in functional printing applications. However their tendency to rapidly oxidize has so far limited their wider use. In this work we have studied the conditions for laser sintering of Cu-NP inks in ambient conditions while avoiding oxidation. We have determined the regime for stable, low-resistivity copper (< ×3 bulk resistivity value) generation in terms of laser irradiance and exposure duration and have indicated the limits on fast processing. The role of pre-drying conditions on sintering outcome has also been studied. A method, based on spectral reflectivity measurements, was used for non-contact monitoring of the sintering process evolution. It also indicates preferred spectral regions for sintering. Finally, we illustrated how selective laser sintering can generate high-quality, fine line (<5 µm wide) and dense copper circuits. (paper)

  1. CO2 pellet blasting studies

    International Nuclear Information System (INIS)

    Archibald, K.E.

    1997-01-01

    Initial tests with CO 2 pellet blasting as a decontamination technique were completed in 1993 at the Idaho Chemical Processing Plant (ICPP) at the Idaho National Engineering Laboratory (INEL). During 1996, a number of additional CO 2 pellet blasting studies with Alpheus Cleaning Technologies, Oak Ridge National Laboratory, and Pennsylvania State University were conducted. After the testing with Alpheus was complete, an SDI-5 shaved CO 2 blasting unit was purchased by the ICPP to test and determine its capabilities before using in ICPP decontamination efforts. Results of the 1996 testing will be presented in this report

  2. Fabrication of (U,Gd)O{sub 2} pellets and development of method for Gd content measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. S.; Song, K. W.; Kang, K. W.; Yang, J. H.; Kim, J. H.; Lee, C. B. [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-05-01

    The goals of the investigation reported herein are to develope the recycling process of defective (U,Gd)O{sub 2} pellets and quality analysis method of sintered (U,Gd)O{sub 2} pellet. (U,Gd){sub 3}O{sub 8} powder is produced by oxidizing defective pellet then mixed with UO{sub 2} and Gd{sub 2}O{sub 3} powder. The mixed powder is milled, pressed and sintered to fabricate (U,Gd)O{sub 2} pellet. In above recycling process, (U,Gd){sub 3}O{sub 8} powder properties and milling condition are greatly affect the final sintered pellet quality of (U,Gd)O{sub 2}. The effects of oxidation temperature and time on powder property of recycled (U,Gd){sub 3}O{sub 8}, and milling method and time of powder mixture on sintered pellet property were investigated. The mixture had Gd{sub 2}O{sub 3} contents of 6 and 10wt% and also had recycled (U,Gd){sub 3}O{sub 8} contents of between 0 to 20wt%, respectively. The properties of sintered pellet such as density, grain size, fraction of cluster, Gd homogeneity are analysed and compared with those of pellets produced by foreign companies. The result shows that our pellet quality is compatible with or better than imported pellets. The more simple and effective way to measure the Gd contents in (U,Gd)O{sub 2} sintered pellet was invented. In first, we oxidized a certain amount of (U{sub 1-x}Gd{sub x})O{sub 2+z} pellet to (U{sub 1-x}Gd{sub x}){sub 3}O{sub 8} powder by annealing between 400{approx}950 .deg. C in air and measured the weight of it(W{sub 1}). And then annealing temperature raised to higher than 950 .deg. C and measured the weight of specimen(W{sub 2}). We found that (U{sub 1-x}Gd{sub x}){sub 3}O{sub 8} phase separated into (U{sub 1-y}Gd{sub y}){sub 4}O{sub 9} and U{sub 3}O{sub 8} in this annealing stage. In addition, the Gd atomic fraction in (U{sub 1-y}Gd{sub y}){sub 4}O{sub 9}, that is y, is independent of initial Gd contents x and has a fixed value. Using above described relations, we can finally found that {chi} in (U{sub 1-x

  3. Effects of feeding corn silage, pelleted, ensiled, or pelleted and ...

    African Journals Online (AJOL)

    Two experiments were conducted to evaluate the effects of corn silage (CS) and alfalfa (pelleted (AP), haylage (AH), or combination (APH)) on lamb growth and carcass characteristics. The objective of Experiment 1 (Exp. 1) was to compare AH to CS in lamb feedlot diets on lamb growth and carcass characteristics.

  4. Spherical neutron generator

    Science.gov (United States)

    Leung, Ka-Ngo

    2006-11-21

    A spherical neutron generator is formed with a small spherical target and a spherical shell RF-driven plasma ion source surrounding the target. A deuterium (or deuterium and tritium) ion plasma is produced by RF excitation in the plasma ion source using an RF antenna. The plasma generation region is a spherical shell between an outer chamber and an inner extraction electrode. A spherical neutron generating target is at the center of the chamber and is biased negatively with respect to the extraction electrode which contains many holes. Ions passing through the holes in the extraction electrode are focused onto the target which produces neutrons by D-D or D-T reactions.

  5. Intelligent Automated Nuclear Fuel Pellet Inspection System

    International Nuclear Information System (INIS)

    Keyvan, S.

    1999-01-01

    At the present time, nuclear pellet inspection is performed manually using naked eyes for judgment and decisionmaking on accepting or rejecting pellets. This current practice of pellet inspection is tedious and subject to inconsistencies and error. Furthermore, unnecessary re-fabrication of pellets is costly and the presence of low quality pellets in a fuel assembly is unacceptable. To improve the quality control in nuclear fuel fabrication plants, an automated pellet inspection system based on advanced techniques is needed. Such a system addresses the following concerns of the current manual inspection method: (1) the reliability of inspection due to typical human errors, (2) radiation exposure to the workers, and (3) speed of inspection and its economical impact. The goal of this research is to develop an automated nuclear fuel pellet inspection system which is based on pellet video (photographic) images and uses artificial intelligence techniques

  6. Sintering uranium oxide in the reaction product of hydrogen-carbon dioxide mixtures

    International Nuclear Information System (INIS)

    De Hollander, W.R.; Nivas, Y.

    1975-01-01

    Compacted pellets of uranium oxide alone or containing one or more additives such as plutonium dioxide, gadolinium oxide, titanium dioxide, silica, and alumina are heated to 900 to 1599 0 C in the presence of a mixture of hydrogen and carbon dioxide, either alone or with an inert carrier gas and held at the desired temperature in this atmosphere to sinter the pellets. The sintered pellets are then cooled in an atmosphere having an oxygen partial pressure of 10 -4 to 10 -18 atm of oxygen such as dry hydrogen, wet hydrogen, dry carbon monoxide, wet carbon monoxide, inert gases such as nitrogen, argon, helium, and neon and mixtures of ayny of the foregoing including a mixture of hydrogen and carbon dioxide. The ratio of hydrogen to carbon dioxide in the gas mixture fed to the furnace is controlled to give a ratio of oxygen to uranium atoms in the sintered particles within the range of 1.98:1 to about 2.10:1. The water vapor present in the reaction products in the furnace atmosphere acts as a hydrolysis agent to aid removal of fluoride should such impurity be present in the uranium oxide. (U.S.)

  7. Structure change of fuel pellets

    International Nuclear Information System (INIS)

    Imanaka, Tetsuji

    1980-01-01

    The investigation of the broken pieces of fuel rods in Mihama No. 1 reactor was carried out in the Japan Atomic Energy Research Institute, and unexpectedly led to the post-irradiation tests. The investigation group of the Kyoto University Research Institute considers that the pursuit of the causes of accident by the government was insufficient, and the countermeasures are problematical, as the result of having examined various reports. In this study, the white foreign phase and swelling of cladding tubes were investigated, because these are especially important in view of the soundness of the fuel. Besides, the possibility of the oxidation of UO 2 pellets by cooling water was examined. It was found by metallographic test that the featuring phase different from UO 2 structure existed in the central part of pellets remaining in two broken fuel rod pieces. The report of JAERI judged that it is the product of solid phase reaction above a certain threshold temperature. The change of pellet structure observed in the white foreign phase and the swell of a cladding tube was caused by the oxidation of UO 2 pellets by primary coolant. The result of observation of the white foreign phase showed that it had been liquid phase at the time of the formation. From the thermodynamic examination based on oxygen potential, UO 2 is oxidized above 1100 deg C in the atmosphere of primary coolant. The liquid phase of the oxidized phase of UO 2 is formed above 1600 deg C. (Kako, I.)

  8. Fundamentals of Biomass pellet production

    DEFF Research Database (Denmark)

    Holm, Jens Kai; Henriksen, Ulrik Birk; Hustad, Johan Einar

    2005-01-01

    to describe the forces acting on the pellet in the die. Important model parameters are the sliding friction coefficient, the ratio of compression and the material specific parameters such as the elastic moduli and the Poisson's ratio. Model calculations show how variation in the characteristic parameters...

  9. Models of current sintering

    Science.gov (United States)

    Angst, Sebastian; Engelke, Lukas; Winterer, Markus; Wolf, Dietrich E.

    2017-06-01

    Densification of (semi-)conducting particle agglomerates with the help of an electrical current is much faster and more energy efficient than traditional thermal sintering or powder compression. Therefore, this method becomes more and more common among experimentalists, engineers, and in industry. The mechanisms at work at the particle scale are highly complex because of the mutual feedback between current and pore structure. This paper extends previous modelling approaches in order to study mixtures of particles of two different materials. In addition to the delivery of Joule heat throughout the sample, especially in current bottlenecks, thermoelectric effects must be taken into account. They lead to segregation or spatial correlations in the particle arrangement. Various model extensions are possible and will be discussed.

  10. Production of pure sintered alumina

    International Nuclear Information System (INIS)

    Rocha, J.C. da; Huebner, H.W.

    1982-01-01

    With the aim of optimizing the sintering parameters, the strength of a large number of alumina samples was determined which were produced under widely varying sintering conditions and with different amounts of MgO content. The strength as a function of sintering time or temperature was found to go through a maximum. With increasing time, this maximum is shifted to lower temperatures, and with decreasing temperature to longer times. Data pairs of sintering times and temperatures which yeld the strength maximum were determined. The value of the strength at the maximum remains unchanged. The strength is high (= 400 MN/m 2 , at a grain size of 3 um and a porosity of 2 per cent) and comparable to foreign aluminas produced for commercial purposes, or even higher. The increase in the sintering time from 1 h to 16 h permits a reduction of the sintering temperature from 1600 to 1450 0 C without losing strength. The practical importance of this fact for a production of sintered alumina on a large scale is emphasized. (Author) [pt

  11. Pellet fired appliances. Market survey. 7. rev. ed.; Pelletheizungen. Marktuebersicht

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-01-15

    The market survey under consideration reports on pellet central heating systems and pellet fired appliances. The main chapters of this market survey are concerned to: (1) Information on wood pellets and pellet fired appliances; (2) Information about the interpretation of the market survey; (3) Survey of all compared pellet fired appliances with respect to the nominal power; (4) Price lists of pellet fired appliances and pellet central heating systems; (5) Type sheets of the compared pellet fired appliances and pellet central heating systems. Finally, this brochure contains the addresses of the produces and distribution partners of pellet fired appliances and pellet central heating systems.

  12. Synthesis of pellet-type red mud adsorbents for removal of heavy metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung-Sik; Han, Sang-Won; Hwang, In-Gook; Bae, Jae-Heum; Choi, Woo-Zin [The University of Suwon, Whasung(Korea)

    2000-02-28

    Red mud is generated as a by-product in the production of Al(OH){sub 3}/Al{sub 2}O{sub 3} from bauxite ore. In this study the pellet-type adsorbents have been made from the red mud, and their adsorption capacities of heavy metal ions have been tested. The pellet-type adsorbents were synthesized to utilize the excellent adsorption capacity of the powder-type adsorbent for industrial application. The pellet-type adsorbents were prepared by mixing several kinds of additives with the red mud. It is found that the pellet-type adsorbent, made by sintering a mixture of red mud (96.0 wt%), polypropylene (2.5 wt%), fly ash (0.5 wt%), and sodium meta-silicate (1.0 wt%) at 1200 deg.C for 30 minutes, has the highest adsorption capacity. In this work, the two kinds of pellet-type adsorbents (bead-type, crushed-type) were prepared. The crushed-type adsorbent was found to show a better adsorption/desorption performance than the bead-type adsorbent. The crushed-type adsorbent showed a good adsorption capacity of Pb{sup 2+} like the powder-type adsorbent. (author). 13 refs., 5 tabs., 13 figs.

  13. Dissolution of UO2 pellets by electrography for isotope ratio analysis

    International Nuclear Information System (INIS)

    Guereli, L.; Uzmen, R.; Colak, L.; Can, F.

    2002-01-01

    Full text: A method for dissolving UO 2 pellets by using electrography is investigated. Electrography, a method used for rapid identification and qualitative analysis of certain materials was widely used in 1950s. However due to the limitations of the method it is rarely used today. The principle of the method involves anodic dissolution of metallic samples and transfer of the ions to a carrier medium usually a filter paper. Color development is used for identification. Sintered UO 2 pellets are difficult to dissolve and the procedure is time consuming. In case of illicit trafficking incidents, the amount of material may be limited and there usually is a deadline for the results, therefore dissolving the whole pellet is not preferred in most cases. In this study, a method rapid dissolving of UO 2 pellets by an electrograph is investigated. A sheet of qualitative filter paper is soaked in a suitable electrolyte and partially dried. It is placed on the cathode of the instrument. The pellet is placed between the anode and the cathode, a DC current is applied. The dissolved ions are transferred to the filter paper which is washed and diluted to the volume for analysis. Two different electrolytes, dissolving time and DC current were tried. The method is rapid, uses very little sample for analysis. Although it is usually applied to metals, acceptable dissolved amounts for analysis were obtained for UO 2 . 30-50 mA current for 2-5 minutes were sufficient for this application. (author)

  14. Effects of Sintering on the Thermal and Optical Properties of Zinc Oxide Ceramic

    Science.gov (United States)

    Tabasco-Novelo, C.; May-Crespo, J.; Ramírez-Rincón, J. A.; Forero-Sandoval, I. Y.; Rodríguez-Gattorno, G.; Quintana, P.; Alvarado-Gil, J. J.

    2018-02-01

    Microstructure and composition are factors determining heat transfer in ZnO ceramic materials, which define the performance of the material after Joule heating, generated by electron transport. In this study, photothermal radiometry was applied to investigate the influence of the sintering temperature, ranging from 800 {°}C to 1300 {°}C, by measuring the thermal diffusivity and thermal conductivity at room temperature, of commercial and sol-gel ZnO pellets. Our results show that the values of these thermal properties for both types of ZnO increase when the sintering temperature increases, displaying maximum energy dissipation at 1200 {°}C. Additionally, the role of the sintering temperature on the optical properties was also analyzed using diffuse reflectance spectroscopy, and from these data the optical band-gap was obtained.

  15. Effect of torrefaction on oil palm empty fruit bunch pelletization ...

    African Journals Online (AJOL)

    The pelletizing properties were determined using single pellet press and pellet stability was determined by compression testing. Pelletization of raw and torrified empty fruit bunch (EFB) from compression single pellet press (SPP) was investigated to quantify the energy consumption and pellet properties including moisture ...

  16. Effects of ball milling and sintering on alumina and alumina-boron compounds

    Science.gov (United States)

    Cross, Thomas

    Alumina has a wide variety of applications, but the processing of alumina based materials can be costly. Mechanically milling alumina has been shown to enhance the sintering properties while decreasing the sintering temperature. Additions of boron have also proven to increase sintering properties of alumina. These two processes, mechanical milling and boron additions, will be combined to test the sintering properties and determine if they are improved upon even further compared to the individual processes. Multiple samples of pure alumina, 0.2 weight percent boron, and 1.0 weight percent boron are batched and processed in a ball mill for different time intervals. These samples are then characterized to observe the structure and properties of the samples after milling but before sintering. Pellets are dry pressed from the milled powders, sintered at 1200°C for one to 10 hours, and characterized to determine the impact of processing. X-ray diffractometry (XRD) was used on each sample to determine crystallite size and lattice parameters at different stages throughout the experiment. XRD was also used to identify any samples with an aluminum borate phase. Scanning electron microscopy (SEM) was used to observe the powder and pellet morphology and to measure bulk chemical composition. Samples were sputter coated with an Au-Pd coating observed in the SEM to characterize the topography as a function of variables such as milling time, boron composition, and sintering time. Additionally, porosity and change in diameter were measured to track the sintering process. Milling sample for longer periods of time would be unnecessary due to the crystallite size leveling off between 10 and 12 hours of milling time. Samples of alumina with 0.2 weight percent boron prove to have very little effect on the sintering properties. At 1.0 weight percent boron, there are changes in diffraction patterns and topography after being sintered for one hour. The porosities of all of the sintered

  17. Fabrication, characteristics, and in-pile performance of UO2 pellets prepared from dry route powder

    International Nuclear Information System (INIS)

    Chotard, A.; Ledac, A.; Bernardin, M.

    1991-01-01

    The dry route conversion process of UF 6 to sinterable UO 2 powder has been used in France on a large scale for more than 10 years for the fabrication of PWR fuels. Thus, our fabrication and irradiation experience relates to more than 10,000 tons of fuel. As everyone knows, the dry route conversion process only involves gas-gas and gas-solid reactions which present the advantage of producing very little contaminated wastes and no liquid effluents. Powders obtained by this process are characterized by: - a very high purity, - a low specific surface area (around 2 m 2 /g), therefore a high resistance to spontaneous oxidation, - a good compressibility, - a very high sinterability (.98% T.D.), - a very high reproducibility. This powder also shows a high fineness which leads to very homogeneous blends with additives like pore former, U 3 O 8 or Gd 2 O 3 . On the other hand this fineness requires a granulation step which is actually not a disadvantage since it allows to adjust the granulate size to optimize the filling of press dies and so as to guarantee a good stability of the pellet dimensions and density. This pelletizing process leads to pellets characterized by: - a good thermal stability (0.5% T.D. after 34 hours at 1700degC), - no open porosity, - low H 2 content (0,3 ppm), - an homogeneous microstructure (grain size and porosity). Such characteristics mean that the UO 2 pellets from dry route conversion present an excellent in pile behaviour for high burnup up to 58,000 MWd/MtU in commercial plant, with: - low fission gas release, - good dimensional stability (densification, swelling), of which examples and results of PIE are described in the paper. The qualities of the dry route conversion powder and its flexibility of use make it possible to consider adjustment of the pellet characteristics, mainly: density, grain size and pore size distribution for specific uses or performance upgrade. (orig.)

  18. Thermal stability test of UO{sub 2}-doped pellet manufactured at INB

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Diogo R., E-mail: diogoribeiro@inb.gov.br [Indústrias Nucleares do Brasil S.A. (FCN/INB), Resende, RJ (Brazil). Fábrica de Combustível Nuclear; Freitas, Artur C., E-mail: artur.freitas@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    The thermal stability test of UO{sub 2}-doped pellet manufactured at INB was carried out in order to analyze the resintering behavior. This analysis is fundamental for predicting dimensional behavior during irradiation. INB commonly performs resintering test to qualify its production lots, and the same methodology was applied to UO{sub 2}-doped pellets. In this preliminary study, three sets of experiments have been made: 1) without any chemical additive (Z test, the standard UO{sub 2} pellets - undoped); 2) UO{sub 2} pellets doped with 0.1, 0.2 and 0.3 wt% of Al{sub 2}O{sub 3}; and 3) 0.1, 0.2 and 0.3 wt% of Nb{sub 2}O{sub 5}. The preliminary results showed an increase in sintered density in all resintering experiments. So as to obtain the percentage increase, the theoretical densities (g/cm{sup 3} and %TD) were calculated based on the undoped UO{sub 2} pellets. All samples increased in a range of 0.27 to 0.32 %TD the out-pile densification during the resintering process. However, the Z(Nb)3 test showed the lowest value of 0.08 %TD, which is not in agreement with the INB specification limits. The sintered density of this test (0.3 wt% niobia) was 96.15% TD. This fact might be related to the competitive mechanism between Kirkendall effect, forming porosity owing to niobium solubilization on UO{sub 2} matrix, and densification process as a result of uranium diffusivity. Thus, the densification was only 0.08 %TD in Z(Nb)3 sample. All the other samples were in agreement with INB specification. (author)

  19. Sintering by hot isostatic pressing (HIP) and spark plasma sintering (SPS) of silicon carbide (SiC) nano-particles synthesized by laser pyrolysis pilot scale; Frittage par compression isostatique a chaud (CIC) et spark plasma sintering (SPS) de nanoparticules en carbure de silicum (SiC) synthetisees a echelle pilote par pyrolyse laser

    Energy Technology Data Exchange (ETDEWEB)

    Mengeot, C.; Guizard, B.; Tenegal, F. [CEA Saclay (DRT/DTNM/LTMEx), 91 - Gif-sur-Yvette (France); Poissonnet, S.; Boulanger, L. [CEA Saclay (DEN/DMN/SRMP), 91 - Gif-sur-Yvette (France); Le Flem, M. [CEA Saclay (DEN/DMN/SRMA/LA2M), 91 - Gif-sur-Yvette (France); Guillard, F. [Centre National de la Recherche Scientifique (CNRS/CEMES), 31 - Toulouse (France)

    2007-07-01

    Pure or with sintering additives (Al{sub 2}O{sub 3} + Y{sub 2}O{sub 3}) SiC nano-particles (20 nm) synthesised by laser pyrolysis at pilot scale were first cold pressed under 1 GPa and then sintered by Hot Isostatic Pressing (HIP) and Spark Plasma Sintering (SPS). Pure SiC samples densified by HIP have a higher density (95%) than SPS ones (80%). With help of sintering additives, both HIP and SPS samples are near theoretical density. Smaller grain size were observed for HIP pellets (pure {approx}35 nm and with additives {approx}100 to 200 nm). Whereas SPS samples grain size were between 100 nm and 1 m. A primary mechanical properties study demonstrates a hardness (28 GPa) and a toughness (6.5 MPa m{sup 1/2}) optimum when crystallite size is around 200 nm. (authors)

  20. Power from Pellets Technology and Applications

    CERN Document Server

    Döring, Stefan

    2013-01-01

    This book provides a practical description of the technology of pellet production on the basis of renewable sources as well as the utilization of pellets. The author explains what kinds of biomass are usable in addition to wood, how to produce pellets and how to use pellets to produce energy. Starting with the basics of combustion, gasification and the pelletizing process, several different technologies are described. The design, planning, construction and economic efficiency are discussed as well. The appendix gives useful advice about plant concepts, calculations, addresses, conversion tables and formulas.

  1. PELLETIZING TESTS OF WASTE ANTHRACITE DUST

    Directory of Open Access Journals (Sweden)

    Michał Rejdak

    2016-09-01

    Full Text Available The results of pelletization tests of waste anthracite dust with three types of starch binder, which were performed at the Institute for Chemical Processing of Coal have been presented. The raw material used in pelletization tests was fine-grained anthracite fraction derived from one of the industrial plants processing anthracite. The aim of the research was to determine the possibilities of waste anthracite dust use in terms of its pelletization and determination of the influence of the binder amount on the physico-chemical properties of the obtained pellets. It was stated out that the application of 2,5% starch binder allows obtaining pellets with adequate mechanical strength.

  2. The Effect of MnO2 Content and Sintering Atmosphere on The Electrical Properties of Iron Titanium Oxide NTC Thermistors using Yarosite

    Science.gov (United States)

    Wiendartun; Gustaman Syarif, Dani

    2017-02-01

    The effect of MnO2 content and sintering atmosphere on the characteristics of Fe2TiO5 ceramics for Negative Thermal Coefficient (NTC) thermistors by using Fe2O3 derived from yarosite has been studied. The ceramics were produced by pressing a homogeneous mixture of Fe2O3, TiO2 and MnO2 (0-2.0 w/o) powders in appropriate proportions to produce Fe2TiO5 based ceramics and sintering the pressed powder at 1100-1200°C for 3 hours in air, O2 and N2 gas. Electrical characterization was done by measuring electrical resistivity of the sintered ceramics at various temperatures from 30°C to 200°C. Microstructure and structural analyses were also carried out by using an scanning electron microscope (SEM) and x-ray diffraction (XRD). The XRD data showed that the pellets crystallize in orthorhombic. The presence of second phase could not be identified from the XRD analyses. The SEM images showed that the grain size of pellet ceramics increase with increasing of MnO2 addition, and the grains size of the ceramic sintered in oxygen gas is smaller than sintered in nitrogen gas. Electrical data showed that the value of room temperature resistance (RRT) tend to decrease with respect to the increasing of MnO2 addition and the pellet ceramics sintered in oxygen gas had the largest thermistor constant (B), activation energy (Ea), sensitivity (α) and room temperature resistance (RRT), compared to the sintered in nitrogen gas. From the electrical characteristics data, it was known that the electrical characteristics of the Fe2TiO5 pellet ceramics followed the NTC characteristic. The fabricated Fe2TiO5 ceramics have thermistor constants (B = 2207-7145K). This can be applied as temperature sensor, and will fulfill the market requirement.

  3. The sintering of nitrogen ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hampshire, S.

    1986-01-01

    The mechanism of densification with oxide additives and the role of the ..cap alpha..-BETA phase transformation is investigated in a detailed kinetic study. Selected compositions in the Si-Al-O-N system are detailed, with and without additives. Although the work is mainly concerned with the identification of the mechanisms of sintering, some property measurements on a sintered BETA-sialon are reported and the feasibility of preparing pure ..cap alpha..-sialon phases is explored.

  4. Method of sintering ceramic materials

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  5. Wood pellets : a worldwide fuel commodity

    International Nuclear Information System (INIS)

    Melin, S.

    2005-01-01

    Aspects of the wood pellet industry were discussed in this PowerPoint presentation. Details of wood pellets specifications were presented, and the wood pellet manufacturing process was outlined. An overview of research and development activities for wood pellets was presented, and issues concerning quality control were discussed. A chart of the effective calorific value of various fuels was provided. Data for wood pellet mill production in Canada, the United States and the European Union were provided, and various markets for Canadian wood pellets were evaluated. Residential sales as well as Canadian overseas exports were reviewed. Production revenues for British Columbia and Alberta were provided. Wood pellet heat and electricity production were discussed with reference to prefabricated boilers, stoves and fireplaces. Consumption rates, greenhouse gas (GHG) emissions, and fuel ratios for wood pellets and fossil fuels were compared. Price regulating policies for electricity and fossil fuels have prevented the domestic expansion of the wood pellet industry. There are currently no incentives for advanced biomass combustion to enter British Columbia markets, and this has led to the export of wood pellets. It was concluded that climate change mitigation policies will be a driving force behind market expansion for wood pellets. tabs., figs

  6. Electrothermal plasma gun as a pellet injector

    International Nuclear Information System (INIS)

    Kincaid, R.W.; Bourham, M.A.

    1994-01-01

    The NCSU electrothermal plasma gun SIRENS has been used to accelerate plastic (Lexan polycarbonate) pellets, to determine the feasibility of the use of electrothermal guns as pellet injectors. The use of an electrothermal gun to inject frozen hydrogenic pellets requires a mechanism to provide protective shells (sabots) for shielding the pellet from ablation during acceleration into and through the barrel of the gun. The gun has been modified to accommodate acceleration of the plastic pellets using special acceleration barrels equipped with diagnostics for velocity and position of the pellet, and targets to absorb the pellet's energy on impact. The length of the acceleration path could be varied between 15 and 45 cm. The discharge energy of the electrothermal gun ranged from 2 to 6 kJ. The pellet velocities have been measured via a set of break wires. Pellet masses were varied between 0.5 and 1.0 grams. Preliminary results on 0.5 and 1.0 g pellets show that the exit velocity reaches 0.9 km/s at 6 kJ input energy to the source. Higher velocities of 1.5 and 2.7 km/s have been achieved using 0.5 and 1.0 gm pellets in 30 cm long barrel, without cleaning the barrel between the shots

  7. Pelletizing properties of torrefied wheat straw

    DEFF Research Database (Denmark)

    Stelte, Wolfgang; Nielsen, Niels Peter; Hansen, Hans Ove

    2013-01-01

    Combined torrefaction and pelletization are used to increase the fuel value of biomass by increasing its energy density and improving its handling and combustion properties. However, pelletization of torrefied biomass can be challenging and in this study the torrefaction and pelletizing properties...... of wheat straw have been analyzed. Laboratory equipment has been used to investigate the pelletizing properties of wheat straw torrefied at temperatures between 150 and 300 °C. IR spectroscopy and chemical analyses have shown that high torrefaction temperatures change the chemical properties of the wheat...... straw significantly, and the pelletizing analyses have shown that these changes correlate to changes in the pelletizing properties. Torrefaction increase the friction in the press channel and pellet strength and density decrease with an increase in torrefaction temperature....

  8. Profile of yttrium segregation in BaCe0,9Y0,1O3-δ as function of sintering temperature

    International Nuclear Information System (INIS)

    Hosken, C.M.; Souza, D.P.F. de

    2010-01-01

    Researches on solid oxide fuel cells indicate barium cerate perovskite as a very attractive material for using as electrolyte due to its high protonic conductivity. The objective of this work is investigate the yttrium segregation during sintering of BaCe 0,9 Y 0,1 O 3-δ doped with Zn O as a sintering aid. The powders were prepared by citrate process. Powders were isostatic pressed into pellets and sintered in air at 1200, 1275, 1325 and 1400 deg C. The samples were characterized by scanning electron microscopy, X-ray diffraction and impedance spectroscopy. Secondary phase containing Yttrium and Cerium was detected as sintering temperature increased. Increase of the lattice parameter and activation energy for electrical conductivity were also detected on samples sintered at 1400 deg C. (author)

  9. A Characterization Research of UO2 Powder for UO2 Pellet Fabrication of Candu Type

    International Nuclear Information System (INIS)

    Rachmawati, M.

    1998-01-01

    A characterization research of of UO 2 powder for UO 2 pellet fabrication of Candu type is reported in this paper. The research has been conducted by characterizing sinterability, compactibility, and compressibility of UO 2 (Cameco) without a pre-compacting and UO 2 powder the result of a pre-compacting. The pre-compacting UO 2 powder has been done to have particle size to less than 150 mu (150-800) mu, and more than 800 mu with distribution varied. Sinterability of each group of particle sizes is analyzed using Thermogravimetric-Differential Thermal Analysis (TG-DTA). Then the final compacting to the powder is done using compaction pressure varied from 1 MP to 4 MP to the all groups of the particle sizes to find the optimum pressure by measuring the density and mechanical strength of the UO 2 green pellet. Both measurements are performed using Micrometer and Universal Testing Machine respectively. The result of this investigation shows that the group of UO 2 powder with no pre-compacting with particle size of less than 150 mu with 60% distribution and (150-800) mu size with 40% distribution are the UO 2 pellets which are eligible in terms of their density and mechanical strength

  10. Space Propulsion via Spherical Torus Fusion Reactor

    International Nuclear Information System (INIS)

    Williams, Craig H.; Juhasz, Albert J.; Borowski, Stanley K.; Dudzinski, Leonard A.

    2003-01-01

    A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 204 days, with an initial mass in low Earth orbit of 1630 mt. Engineering conceptual design, analysis, and assessment were performed on all major systems including nuclear fusion reactor, magnetic nozzle, power conversion, fast wave plasma heating, fuel pellet injector, startup/re-start fission reactor and battery, and other systems. Detailed fusion reactor design included analysis of plasma characteristics, power balance and utilization, first wall, toroidal field coils, heat transfer, and neutron/X-ray radiation

  11. [Effect of pretreatment by solid-state fermentation of sawdust on the pelletization and pellet's properties].

    Science.gov (United States)

    Guo, Jingjing; Yuan, Xingzhong; Li, Hui; Li, Changzhu; Xiao, Zhihong; Xiao, Zhihua; Jiang, Longbo; Zeng, Guangming

    2015-10-01

    We pretreated sawdust (Castanopsis fissa Rehd.et Wils) by solid state fermentation (SSF) with Phanerochaete chrysosporium, and then compressed it into pellets with the moisture content of 15% and the pressure of 98 MPa, to solve the problem of low density, low Meyer hardness, high water uptake, and short storage period of pellet in the woody pellet industry. We studied the effects of fermentation time on pelletization and pellets's characteristics (including energy consumption, density, Meyer hardness, and hydrophobicity). SSF affected the heating values of pellet. Compared with fresh sawdust, SSF consumed more energy at the maximal value by 6.98% but saved extrusion energy by 32.19% at the maximum. Meanwhile, SSF could improve the density, Meyer hardness and hydrophobicity of pellet. Pellet made of sawdust pretreated by SSF for 48 d had best quality, beneficial for long-term transportation and storage of pellets.

  12. Entrapment of andrographolide in cross-linked alginate pellets: II. Physicochemical characterization to study the pelletization of andrographolide.

    Science.gov (United States)

    Shariff, Arshia; PK, Manna; KLK, Paranjothy; M, Manjula

    2007-01-01

    This paper deals with the characterization of pellets containing andrographolide in two parts. The first part deals with characterization of the pellets to ascertain the identity and integrity of andrographolide. Part two involves characterization of the pellets containing Andrographis paniculata extract (33.3%) prepared in the paper I for their micromeritic properties like Particle size, Particle size distribution, Sphericity measurements like Shape ratio and Aspect ratio, Tapped density, Compressibility index, Hausner's ratio and Angle of repose. In addition, our aim was also to derive information about the mechanism of gelation with entrapment of andrographolide to supplement results obtained about the release mechanisms deduced in paper I. Since this work requires use of techniques like FTIR, FTRaman, MTDSC and XRPD, it was necessary to prepare alginate micropellets using pure andrographolide (99.89%) rather than the multicomponent extract using the same procedure discussed in paper I. The integrity of the drug was maintained in the cross-linked micropellets as was seen in the MTDSC and FTIR spectra supported by the FTRaman spectra. The depolymerisation transitions, the reversing and non-reversing heat flow signals were determined using the MTDSC and interpreted to study the mechanism of pelletization. The MTDSC profiles also confirmed the integrity of the drug by exhibiting a sharp endotherm at 232(o)c that is the melting point of andrographolide. The XRPD spectrum of the micropellets ascertained that the crystallinity of andrographolide was maintained. The relationship of the nature of the drug present in the micropellets related to release mechanisms is discussed. In conclusion, it can be said that andrographolide can be successfully incorporated into cross-linked micropellets of alginate without affecting its integrity or nature to deliver it as a bitterless monoherbal preparation.

  13. Microstructural optimization of solid-state sintered silicon carbide

    Science.gov (United States)

    Vargas-Gonzalez, Lionel R.

    Silicon carbide armor, manufactured through solid-state sintering, liquid-phase sintering, and hot-pressing, is being used by the United States Armed Forces for personal and vehicle protection. There is a lack of consensus, however, on which process results in the best-performing ballistic armor. Previous studies have shown that hot-pressed ceramics processed with secondary oxide and/or rare earth oxides, which exhibit high fracture toughness, perform well in handling and under ballistic impact. This high toughness is due to the intergranular nature of the fracture, creating a tortuous path for cracks and facilitating crack deflection and bridging. However, it has also been shown that higher-hardness sintered SiC materials might perform similarly or better to hot-pressed armor, in spite of the large fracture toughness deficit, if the microstructure (density, grain size, purity) of these materials are improved. In this work, the development of theoretically-dense, clean grain boundary, high hardness solid-state sintered silicon carbide (SiC) armor was pursued. Boron carbide and graphite (added as phenolic resin to ensure the carbon is finely dispersed throughout the microstructure) were used as the sintering aids. SiC batches between 0.25--4.00 wt.% carbon were mixed and spray dried. Cylindrical pellets were pressed at 13.7 MPa, cold-isostatically pressed (CIP) at 344 MPa, sintered under varying sintering soaking temperatures and heating rates, and varying post hot-isostatic pressing (HIP) parameters. Carbon additive amounts between 2.0--2.5 wt.% (based on the resin source), a 0.36 wt.% B4C addition, and a 2050°C sintering soak yielded parts with high sintering densities (˜95.5--96.5%) and a fine, equiaxed microstructure (d50 = 2.525 mum). A slow ramp rate (10°C/min) prevented any occurrence of abnormal grain growth. Post-HIPing at 1900°C removed the remaining closed porosity to yield a theoretically-dense part (3.175 g/cm3, according to rule of mixtures). These

  14. Energy wood. Part 2b: Wood pellets and pellet space-heating systems

    International Nuclear Information System (INIS)

    Nussbaumer, T.

    2002-01-01

    The paper gives an overview on pellet utilization including all relevant process steps: Potential and properties of saw dust as raw material, pellet production with drying and pelletizing, standardization of wood pellets, storage and handling of pellets, combustion of wood pellets in stoves and boilers and applications for residential heating. In comparison to other wood fuels, wood pellets show several advantages: Low water content and high heating value, high energy density, and homogeneous properties thus enabling stationary combustion conditions. However, quality control is needed to ensure constant properties of the pellets and to avoid the utilization of contaminated raw materials for the pellet production. Typical data of efficiencies and emissions of pellet stoves and boilers are given and a life cycle analysis (LCA) of wood pellets in comparison to log wood and wood chips is described. The LCA shows that wood pellets are advantageous thanks to relatively low emissions. Hence, the utilization of wood pellet is proposed as a complementary technology to the combustion of wood chips and log wood. Finally, typical fuel cost of wood pellets in Switzerland are given and compared with light fuel oil. (author)

  15. Use of crospovidone as pelletization aid as alternative to microcrystalline cellulose: effects on pellet properties.

    Science.gov (United States)

    Verheyen, P; Steffens, K-J; Kleinebudde, P

    2009-11-01

    Microcrystalline cellulose (MCC) is the most important pelletization aid in extrusion/spheronization. Because of known disadvantages, the search for substitutes is ongoing. In this context, crospovidone has proven to offer substantial advantages as pelletization aid because of its ability to turn low-soluble active ingredients into fast-dissolving stable pellets. Pellets from crospovidone with different amounts of paracetamol, hydrochlorothiazide, and spironolactone as model drugs were prepared by extrusion/spheronization. For comparison, pellets with MCC as extrusion aid were also produced. The pellets of different formulations were evaluated in terms of yield, aspect ratio, mean Feret diameter, 10% interval fraction, tensile strength, disintegration, and drug release profile. Only crospovidone types exhibiting small particle sizes are suitable as pelletization aid. While maintaining the pharmaceutical quality aspects, it was possible to incorporate up to 60% (w/w) active pharmaceutical ingredients (API) into pellets with crospovidone. The most distinguished differences between pellets based on crospovidone and MCC are the disintegration and drug release behavior. The pellets containing binary mixtures of the low-soluble APIs and crospovidone resulted in fast release in contrast to the pellets with MCC as pelletization aid, which exhibited a slow release. Crospovidone shows an excellent behavior as pelletization aid and produces fast-releasing pellets even with low-soluble APIs.

  16. Studies on the synthesis of nanocrystalline Y{sub 2}O{sub 3} and ThO{sub 2} through volume combustion and their sintering

    Energy Technology Data Exchange (ETDEWEB)

    Sanjay Kumar, D. [Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Ananthasivan, K., E-mail: asivan@igcar.gov.in [Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Venkata Krishnan, R. [Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Amirthapandian, S. [Material Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India); Dasgupta, Arup [Microscopy and Thermo-Physical Property Division, Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603102, Tamil Nadu (India)

    2016-10-15

    Volume combustion was observed in the auto-ignition of the citrate gels containing the nitrates of yttrium/thorium for the first time in mixture with a fuel (citric acid) to oxidant (Y{sup 3+} or Th{sup 4+} nitrate) ratio close to that demanded by the stoichiometry. These nanocrystalline powders were characterized for their bulk density, specific surface area, particle size distribution, carbon residue and X-ray crystallite size and were sintered by both the conventional and the two-step method. The maximum relative sintered density of Y{sub 2}O{sub 3} was 98.9% TD. The sintered density of thoria (97.8% TD) is the highest among the values reported so far, for nanocrystalline ThO{sub 2}. Characterization of the pellets and powders by using scanning electron microscopy and transmission electron microscopy reaffirmed nanocrystallinity and that the sintered pellets comprised faceted sintered grains. The two-step sintering was found to restrict “runaway” sintering. - Highlights: • Scaled-up synthesis of nanocrystalline Y{sub 2}O{sub 3} and ThO{sub 2} using citrate gel-combustion method. • VCR was observed at a fuel to nitrate ratio (R) of 0.125 and 0.17 in mixtures containing Th(NO{sub 3}){sub 4} and Y(NO{sub 3}){sub 3} respectively. • The calcined powders were compacted and sintered by using a novel two-step sintering method. • Sintered densities as high as 97.8% T.D. (ThO{sub 2}, T{sub H} = 0.48) and 98.9% T.D. (Y{sub 2}O{sub 3}, T{sub H} = 0.61) were obtained.

  17. Spherically Actuated Motor

    Science.gov (United States)

    Peeples, Steven

    2015-01-01

    A three degree of freedom (DOF) spherical actuator is proposed that will replace functions requiring three single DOF actuators in robotic manipulators providing space and weight savings while reducing the overall failure rate. Exploration satellites, Space Station payload manipulators, and rovers requiring pan, tilt, and rotate movements need an actuator for each function. Not only does each actuator introduce additional failure modes and require bulky mechanical gimbals, each contains many moving parts, decreasing mean time to failure. A conventional robotic manipulator is shown in figure 1. Spherical motors perform all three actuation functions, i.e., three DOF, with only one moving part. Given a standard three actuator system whose actuators have a given failure rate compared to a spherical motor with an equal failure rate, the three actuator system is three times as likely to fail over the latter. The Jet Propulsion Laboratory reliability studies of NASA robotic spacecraft have shown that mechanical hardware/mechanism failures are more frequent and more likely to significantly affect mission success than are electronic failures. Unfortunately, previously designed spherical motors have been unable to provide the performance needed by space missions. This inadequacy is also why they are unavailable commercially. An improved patentable spherically actuated motor (SAM) is proposed to provide the performance and versatility required by NASA missions.

  18. Ice sintering timescales at the surface of Europa and implications for surface properties

    Science.gov (United States)

    Phillips, C. B.; Molaro, J.; Meirion-Griffith, G.

    2017-12-01

    The planned exploration of Europa by NASA's Europa Clipper Mission and the possibility of a future Europa lander have driven the need to characterize its surface strength, roughness, porosity, thermal conductivity, and regolith depth in order to accurately interpret remote sensing data and develop appropriate spacecraft landing systems. Many processes contribute to Europa's landscape evolution, such as sputtering, mass wasting, thermal segregation, and impact gardening, driving the creation and distribution of icy regolith across the surface. While the efficacy of these processes are not well constrained, any amount of regolith emplaced at the surface will undergo subsequent processing due to sintering. Ice sintering is a form of frost metamorphism whereby contacting ice grains experience the diffusion of material into their contact region, forming a "neck" between them and densifying over time. Over long enough timescales, ice aggregates will sinter into solid material, which may contribute to the incorporation of non-ice material into Europa's subsurface and help to drive subsurface chemistry. Sintering also interacts with other processes, adding to the complexity of icy surface evolution. For example, sputtering preferentially removes larger grains and may enhance sintering rates, and changes in ice porosity may affect the response of the surface to micrometeorite impacts. Quantifying the effects of ice sintering will allow us to predict the microstructural properties of Europa's surface at spacecraft scales. To this end, we have modeled pressure-less (no overburden) sintering of spherical water-ice grains and validated the results with a laboratory experiment. We also modeled ice at the surface of Europa to obtain a first-order approximation of the sintering timescale and surface properties. Preliminary results indicate that ice grains will experience neck growth but not significant densification over Europa's surface age, suggesting that loose surface ice

  19. Spherical geodesic mesh generation

    Energy Technology Data Exchange (ETDEWEB)

    Fung, Jimmy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kenamond, Mark Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Burton, Donald E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Shashkov, Mikhail Jurievich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-27

    In ALE simulations with moving meshes, mesh topology has a direct influence on feature representation and code robustness. In three-dimensional simulations, modeling spherical volumes and features is particularly challenging for a hydrodynamics code. Calculations on traditional spherical meshes (such as spin meshes) often lead to errors and symmetry breaking. Although the underlying differencing scheme may be modified to rectify this, the differencing scheme may not be accessible. This work documents the use of spherical geodesic meshes to mitigate solution-mesh coupling. These meshes are generated notionally by connecting geodesic surface meshes to produce triangular-prismatic volume meshes. This mesh topology is fundamentally different from traditional mesh topologies and displays superior qualities such as topological symmetry. This work describes the geodesic mesh topology as well as motivating demonstrations with the FLAG hydrocode.

  20. Solid state synthesis and sintering of monazite-type ceramics: application to minor actinides conditioning

    International Nuclear Information System (INIS)

    Bregiroux, D.

    2005-11-01

    In the framework of the French law of 1991 concerning the nuclear waste management, several studies are undertaken to develop specific crystalline conditioning matrices. Monazite, a rare earth (TR 3+ ) orthophosphate with a general formula TR 3+ PO 4 , is a natural mineral containing significant amount of thorium and uranium. Monazite has been proposed as a host matrix for the minor actinides (Np, Am and Cm) specific conditioning, thanks to its high resistance to self irradiation and its low solubility. Its is now of prime importance to check the conservation of these properties on synthesized materials, which implies to master all the stages of the elaboration process, from the powder synthesis to the sintering of controlled microstructure pellets. This work can be divided into two main parts: The first part deals with the synthesis by high temperature solid state route of TR 3+ PO 4 powders (with TR 3+ = La 3+ to Gd 3+ , Pu 3+ and Am 3+ ). The chemical reactions occurring during the firing of starting reagents are described in the case of monazite with only one or several cations. From these results, a protocol of synthesis is described. The incorporation of tetravalent cations (Ce 4+ , U 4+ , Pu 4+ ) in the monazite structure was also studied. The second part of the present work deals with the elaboration of controlled density and microstructure monazite pellets and their related mechanical and thermal properties. The study of crushing and sintering is presented. For the first time, experimental results are confronted with theoretical models in order to deduce the densification and grain growth mechanisms. By the comprehension of the various physicochemical phenomena occurring during the various stages of the monazite pellets elaboration process (powder synthesis, crushing, sintering...), this work allowed the development of a protocol of elaboration of controlled microstructure monazite TR 3+ PO 4 pellets. The determination of some mechanical and thermal

  1. Preparation of pellets containing highly soluble drug by extrusion/spheronisation and coating with Kollicoat® SR 30D

    Directory of Open Access Journals (Sweden)

    Itamar Francisco Andreazza

    2011-04-01

    Full Text Available The aim of this study was to prepare and evaluate the pellets, containing a highly soluble drug (ascorbic acid, by the extrusion-spheronization process and coated with a release controlling polymer. The coating (undertaken in a fluid bed was applied to three batches of the pellets with a dispersion of Kollicoat® SR 30 D, with each batch of pellets receiving a different level of polymer (5.07; 8.26 and 10.35%. The coated pellets were evaluated for sphericity by imaging analysis and comparative dissolution profile with a product commercially available in Brazil. All of the evaluated samples presented adequate physical properties and the dissolution profile of those coated with 5.07% of polymer proved to be similar to that of the commercially available brand name.

  2. Preparation of mullite whiskers reinforced SiC/Al2O3 composites by microwave sintering

    Directory of Open Access Journals (Sweden)

    Wei Li

    2016-12-01

    Full Text Available Mullite whiskers reinforced SiC/Al2O3 composites were prepared by microwave sintering in a microwave chamber with TE666 resonant mode. Original SiC particles were coated with SiO2 using sol-gel processing and mixed with Al2O3 particles. Mullite was formed in the reaction between SiO2 and Al2O3. The isostatically pressed cylindrical pellets were sintered from 1350 °C to 1600 °C for 30 min. Physical and chemical responses were investigated by detecting changes in reflected power during the microwave sintering process. XRD was carried out to characterize the samples and showed that mullite could be formed at 1200 °C. Bridging of mullite whiskers between Al2O3 and SiC particles was observed by SEM and is due to a so-called local hot spot effect, which was the unique feature for microwave sintering. The optimized microwave sintering temperature was 1500 °C corresponding to the maximum amount of mullite whiskers within SiC/Al2O3 composites. The high electro-magnetic field enhanced the decomposition of mullite at higher temperatures above 1550 °C. The mechanical properties of mullite whiskers reinforced SiC/Al2O3 composites are much better than the SiC/Al2O3 composites without mullite whiskers.

  3. Bile salt/phospholipid mixed micelle precursor pellets prepared by fluid-bed coating

    Directory of Open Access Journals (Sweden)

    Dong F

    2013-04-01

    Full Text Available Fuxia Dong,1,2 Yunchang Xie,1 Jianping Qi,1 Fuqiang Hu,3 Yi Lu,1 Sanming Li,2 Wei Wu1 1School of Pharmacy, Fudan University, Key Laboratory of Smart Drug Delivery of Ministry of Education and PLA, Shanghai, People’s Republic of China; 2School of Pharmacy, Shenyang Pharmaceutical University, Liaoning, People’s Republic of China; 3School of Pharmacy, Zhejiang University, Hangzhou, People’s Republic of China Abstract: Bile salt/phospholipid mixed micelles (MMs are potent carriers used for oral absorption of drugs that are poorly soluble in water; however, there are many limitations associated with liquid formulations. In the current study, the feasibility of preparing bile salt/phospholipid MM precursor (preMM pellets with high oral bioavailability, using fluid-bed coating technology, was examined. In this study, fenofibrate (FB and sodium deoxycholate (SDC were used as the model drug and the bile salt, respectively. To prepare the MMs and to serve as the micellular carrier, a weight ratio of 4:6 was selected for the sodium deoxycholate/phospholipids based on the ternary phase diagram. Polyethylene glycol (PEG 6000 was selected as the dispersion matrix for precipitation of the MMs onto pellets, since it can enhance the solubilizing ability of the MMs. Coating of the MMs onto the pellets using the fluid-bed coating technology was efficient and the pellets were spherical and intact. MMs could be easily reconstituted from preMM pellets in water. Although they existed in a crystalline state in the preMM pellets, FB could be encapsulated into the reconstituted MMs, and the MMs were redispersed better than solid dispersion pellets (FB:PEG = 1:3 and Lipanthyl®. The redispersibility of the preMM pellets increased with the increase of the FB/PEG/micellar carrier. PreMM pellets with a FB:PEG:micellar carrier ratio of 1:1.5:1.5 showed 284% and 145% bioavailability relative to Lipanthyl® and solid dispersion pellets (FB:PEG = 1:3, respectively. Fluid

  4. Pellet-plasma interactions in tokamaks

    DEFF Research Database (Denmark)

    Chang, C.T.

    1991-01-01

    The ablation of a refuelling pellet of solid hydrogen isotopes is governed by the plasma state, especially the density and energy distribution of the electrons. On the other hand, the cryogenic pellet gives rise to perturbations of the plasma temperature and density. Based on extensive experimental...... data, the interaction between the pellet and the plasma is reviewed. Among the subjects discussed are the MHD activity, evolution of temperature and density profiles, and the behaviour of impurities following the injection of a pellet (or pellets). The beneficial effect of density peaking on the energy...... of the plasma. The appearance of striations and the curving of the pellet trajectory are discussed in detail. The possibility is described for using these observations to study the plasma current-density distribution as well as the existence of suprathermal electrons....

  5. Pellet fuelling in Tore Supra long discharges

    Science.gov (United States)

    Géraud, A.; Bucalossi, J.; Loarer, T.; Pégourié, B.; Grisolia, C.; Gros, G.; Gunn, J.

    2005-03-01

    A new pellet injector, able to inject continuously hydrogen or deuterium pellets, was installed on Tore Supra in 2003 and preliminary experiments aiming to fuel long discharges were performed. In combination with Lower Hybrid (LH) Current Drive, pure pellet fuelled discharges lasting up to 2 min were achieved. The LH power was switched off just before each pellet injection (LH notching) to maintain a relatively deep pellet penetration by reducing the energy of the super-thermal electrons driven by the LH wave. A comparison, based on a particle balance study, between two comparable pellet fuelled and gas fuelled discharges has been done. In the two cases, the volume average density is the same and the analysis shows that the particle source, the pumped flux and the wall retention are similar and appear to be independent of the fuelling method for the low plasma current and density conditions considered ( Ip = 0.6 MA, = 1.5 × 10 19 m -3).

  6. Sintering study in vertical fixed bed reactor for synthetic aggregate production; Estudo da sinterizacao em reator vertical de leito fixo para producao de agregado sintetico

    Energy Technology Data Exchange (ETDEWEB)

    Quaresma, D.S.; Neves, A.S.S.; Melo, A.O.; Pereira, L.F.S.; Bezerra, P.T.S.; Macedo, E.N.; Souza, J.A.S., E-mail: danysq@gmail.com [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Faculdade de Engenharia Quimica

    2017-04-15

    The synthetic aggregates are being employed in civil construction for the reduction of mineral extraction activities. Within this context, the recycling of industrial waste is the basis of the majority of processes to reduce the exploitation of mineral resources. In this work the sintering in a vertical fixed bed reactor for synthetic aggregate production using 20% pellets and 80% charcoal was studied. The pellets were prepared from a mixture containing clay, charcoal and fly ash. Two experiments varying the speed of air sucking were carried out. The material produced was analyzed by X-ray diffraction, scanning electron microscopy, measures of their ceramic properties, and particle size analysis. The results showed that the solid-state reactions, during the sintering process, were efficient and the produced material was classified as coarse lightweight aggregate. The process is interesting for the sintering of aggregates, and can be controlled by composition, particle size, temperature gradient and gaseous flow. (author)

  7. Geometrical dimensioning of PWR UO2 pellets

    International Nuclear Information System (INIS)

    Silva, A.T.

    1988-08-01

    The finite element structural program SAP-IV is used to calculate UO 2 pellet strains developed under thermal gradients in pressurized water reactors. The applied procedure allows to analyse the influence of various aspects of pelet geometry on cladding strains and can be utilized for the dimensioning of UO 2 pellets. Pellets purchased with flat ends, with dishes pressed into both ends, shouders, and a 45-deg edge chamfer are analysed. The analyse results are compared with experiemtnal data. (author) [pt

  8. Fabrication of granule and pellet heat sources from oxalate-based 238PuO2

    International Nuclear Information System (INIS)

    Bickford, D.F.; Rankin, D.T.

    1975-01-01

    Suitable fuel forms for radioisotopic thermoelectric generators are granules of high internal density (greater than 95 percent of theoretical) or geometric shapes (80 to 90 percent dense) such as pellets or spheres. Both forms can be made from calcined 238 Pu(III) oxalate. The conditions for processing PuO 2 are controlled during fuel form fabrication to ensure pellet integrity; to control density, grain size, and porosity distribution; and to minimize the fraction of potentially respirable fines. The competing phenomena of expansion caused by radiation damage (including helium generation from radioactive decay of plutonium) and shrinkage caused by sintering must be controlled to assure dimensional stability. The variation of microstructure and related physical properties with process parameters is discussed

  9. Completion of UO2 pellets production and fuel rods load for the RA-8 critical facility

    International Nuclear Information System (INIS)

    Marajofsky, Adolfo; Perez, Lidia E.; Thern, Gerardo G.; Altamirano, Jorge S.; Benitez, Ana M.; Cardenas, Hugo R.; Becerra, Fabian A.; Perez, Aldo E.; Fuente, Mariano de la

    1999-01-01

    The Advanced Fuels Division produced fuel pellets of 235 U with 1.8% and 3.6% enrichment and Zry-4 cladding loads for the RA-8 reactor at Pilcaniyeu Technological Unit. For economical and availability reasons, the powder acquired was initially UO 2 with 3.4% enrichment in 235 U, therefore the 235 U powder with 1.8% enrichment was produced by mechanical mixture. The production of fuel pellets for both enrichments was carried out by cold pressing and sintering processes in reducing atmosphere. The load of Zry-4 claddings was performed manually. The production stages can be divided into setup, qualification and production. This production allows not only to fulfill satisfactorily the new fuel rods supply for the RA-8 reactor but also to count with a new equipment and skilled personnel as well as to meet quality and assurance control methods for future pilot-scale production and even new fuel elements production. (author)

  10. Fabrication of (U,Am)O2 pellet with controlled porosity from oxide microspheres

    Science.gov (United States)

    Ramond, Laure; Coste, Philippe; Picart, Sébastien; Gauthé, Aurélie; Bataillea, Marc

    2017-08-01

    U1-xAmxO2±δ mixed-oxides are considered as promising compounds for americium heterogeneous transmutation in Sodium Fast Neutron Reactor. Porous microstructure is envisaged in order to facilitate helium and fission gas release and to reduce pellet swelling during irradiation and under self-irradiation. In this study, the porosity is created by reducing (U,Am)3O8 microspheres into (U,Am)O2 during the sintering. This reduction is accompanied by a decrease of the lattice volume that leads to the creation of open porosity. Finally, an (U0.90Am0.10)O2 porous ceramic pellet (D∼89% of the theoretical density TD) with controlled porosity (≥8% open porosity) was obtained from mixed-oxide microspheres obtained by the Weak Acid Resin (WAR) process.

  11. Sintering diagrams of UO2

    International Nuclear Information System (INIS)

    Mohan, A.; Soni, N.C.; Moorthy, V.K.

    1979-01-01

    Ashby's method (see Acta Met., vol. 22, p. 275, 1974) of constructing sintering diagrams has been modified to obtain contribution diagrams directly from the computer. The interplay of sintering variables and mechanisms are studied and the factors that affect the participation of mechanisms in UO 2 are determined. By studying the physical properties, it emerges that the order of inaccuracies is small in most cases and do not affect the diagrams. On the other hand, even a 10% error in activation energies, which is quite plausible, would make a significant difference to the diagram. The main criticism of Ashby's approach is that the numerous properties and equations used, communicate their inaccuracies to the diagrams and make them unreliable. The present study has considerably reduced the number of factors that need to be refined to make the sintering diagrams more meaningful. (Auth.)

  12. Simulations of JET pellet fuelled ITB plasmas

    Science.gov (United States)

    Garzotti, L.; Garbet, X.; Thyagaraja, A.; de Baar, M. R.; Frigione, D.; Mantica, P.; Parail, V.; Pégourié, B.; Zabeo, L.; EFDA contributors, JET

    2006-01-01

    Experiments were performed on JET where high-density plasmas with an internal transport barrier (ITB) were created by means of combined use of lower hybrid current drive (LHCD) and pellet injection before the barrier formation. Attempts were also made to use pellets to fuel the plasma and to sustain the density during the ITB phase. It was found that shallow pellets ablating in the region r/a >= 0.8 and far from the foot of the barrier did not destroy the ITB, whereas deeper pellets penetrating up to 0.6 CUTIE, a global electromagnetic fluid turbulence code. The results show that for the shallow pellet case all codes reproduce the general features of the experiment, whereas for the deep pellet case, there are differences in the degree of agreement between the different codes and the experiment. Runs performed varying the pellet penetration depth indicate that not only the pellet penetration, but also the barrier strength plays a key role in the dynamics of the pellet-ITB interaction.

  13. Lab and Bench-Scale Pelletization of Torrefied Wood Chips

    DEFF Research Database (Denmark)

    Shang, Lei; Nielsen, Niels Peter K.; Stelte, Wolfgang

    2013-01-01

    content, additive addition, and the degree of torrefaction on the pelletizing properties and pellet quality, i.e., density, static friction, and pellet strength. Results were compared with pellet production using a bench-scale pelletizer. The results indicate that friction is the key factor when scaling...... up from single-pellet press to bench-scale pelletizer. Tuning moisture content or increasing the die temperature did not ease the pellet production of torrefied wood chips significantly. The addition of rapeseed oil as a lubricant reduced the static friction by half and stabilized pellet production...

  14. Enhanced infrared transmittance properties in ultrafine MgAl2O4 nanoparticles synthesised by a single step combustion method, followed by hybrid microwave sintering

    Science.gov (United States)

    Mathew, C. T.; Vidya, S.; Koshy, Jacob; Solomon, Sam; Thomas, Jijimon K.

    2015-09-01

    Infrared transparent ceramics found to have potential applications as infrared windows and domes in strategic defence and space missions. Synthesis of ultrafine nanostructured MgAl2O4 ceramics by a modified single step auto-igniting combustion technique, followed by sintering of the sample by resistive and resistive-microwave hybrid heating to high density and their excellent infrared transmission characteristics are presented in this paper. Structural characterisations of MgAl2O4 nanoparticles reveal that the as prepared powder is phase pure, with average crystallite size ∼15 nm and possess a cubic structure. Optical band gap calculated using the Kubelka-Munk method is 5.75 eV. The thermal stability of the nanopowder at elevated temperatures has been studied using thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). Hybrid heating yield a substantial reduction in sintering temperature and soaking time relative to the conventional resistive heating, and the samples achieved >99% density by microwave-resistive hybrid heating. Scanning electron micrograph (SEM) showed that the pellets are well sintered. The pellet sintered by hybrid heating showed a better transmittance of ∼79% in the UV-Visible region and ∼82% in the mid IR region compared to pellet sintered by resistive heating which has ∼68% in the UV-Visible region and ∼66% in the mid IR region. The results confirm the effective use of nanocrystalline powders from modified combustion synthesis as starting material for the development of high quality IR transparent windows and domes. In addition the microwave hybrid sintering technique employed in the present study also contributes to the results of better transmittance characteristics in highly densified MgAl2O4 ceramic pellets.

  15. Recycling of mill scale in sintering process

    Directory of Open Access Journals (Sweden)

    El-Hussiny N.A.

    2011-01-01

    Full Text Available This investigation deals with the effect of replacing some amount of Baharia high barite iron ore concentrate by mill scale waste which was characterized by high iron oxide content on the parameters of the sintering process., and investigation the effect of different amount of coke breeze added on sintering process parameters when using 5% mill scale waste with 95% iron ore concentrate. The results of this work show that, replacement of iron ore concentrate with mill scale increases the amount of ready made sinter, sinter strength and productivity of the sinter machine and productivity at blast furnace yard. Also, the increase of coke breeze leads to an increase the ready made sinter and productivity of the sintering machine at blast furnace yard. The productivity of the sintering machine after 5% decreased slightly due to the decrease of vertical velocity.

  16. Phosphorus containing sintered alloys (review)

    International Nuclear Information System (INIS)

    Muchnik, S.V.

    1984-01-01

    Phosphorus additives are considered for their effect on the properties of sintered alloys of different applications: structural, antifriction, friction, magnetic, hard, superhard, heavy etc. Data are presented on compositions and properties of phosphorus-containing materials produced by the powder metallurgy method. Phosphorus is shown to be an effective activator of sintering in some cases. When its concentration in the material is optimal it imparts the material such properties as strength, viscosity, hardness, wear resistance. Problems concerning powder metallurgy of amorphous phosphorus-containing alloys are reported

  17. Compactation pressure influence on the thermophysical properties of uranium dioxide fuel pellets produced with kernels

    International Nuclear Information System (INIS)

    Ferreira, Ricardo Alberto Neto; Andrade, Antonio Santos; Miranda, Odair; Grossi, Pablo Andrade; Camarano, Denise das Merces; Migliorini, Fabricio Lima; Silva, Egonn Hendrigo Carvalho; Andrade, Roberto Marcio de

    2009-01-01

    Under compaction pressures ranging from 300 MPa up to 500 MPa, fuel pellets of uranium dioxide were manufactured by the pressing of kernels. These were produced by the sol-gel process developed in Germany by NUKEM for using in high temperature gas cooled reactors, which were absorbed, transferred and implanted at CDTN-Centro de Desenvolvimento da Tecnologia Nuclear. The sintering was performed at 1700 deg C for two hours under argon with 4% hydrogen atmosphere, resulting sintered densities ranging from 9.33 g·cm -3 up to 10.08 g·cm -3 , determined by the xylol penetration-immersion method. Using the flash laser method, the thermophysical properties of the pellets were determined and thermal diffusivity ranging from 2.58 x 10 -6 m 2 ·s -1 up to 2.78 x 10 -6 m 2 ·s -1 and thermal conductivity from 6.22 m -1 ·K -1 up to 7.24 W·m -1 ·K -1 , corresponding to a decreasing of the porosity from 14.88% to 8.05%. The methodology is described and the influence of the compaction pressure on the pellet properties is also analyzed. The thermal conductivity results of this study will be very valuable to a project in development at CDTN, in which uranium dioxide pellets will be produced by the pressing of kernels, with beryllium oxide filling the voids between the kernels in order to enhance the thermal conductivity of the fuel and consequently, the thermal performance of the fuel rod, as required in extended burnup conditions. They will be used as reference to compare and calculate the favorable increase of the thermal conductivity, caused by the addition of beryllium oxide. (author)

  18. Experimental sintering of ash at conduit conditions and implications for the longevity of tuffisites

    Science.gov (United States)

    Gardner, James E.; Wadsworth, Fabian B.; Llewellin, Edward W.; Watkins, James M.; Coumans, Jason P.

    2018-03-01

    Escape of gas from magma in the conduit plays a crucial role in mitigating explosivity. Tuffisite veins—ash-filled cracks that form in and around volcanic conduits—represent important gas escape pathways. Sintering of the ash infill decreases its porosity, eventually forming dense glass that is impermeable to gas. We present an experimental investigation of surface tension-driven sintering and associated densification of rhyolitic ash under shallow conduit conditions. Suites of isothermal (700-800 °C) and isobaric H2O pressure (20 and 40 MPa) experiments were run for durations of 5-90 min. Obsidian powders with two different size distributions were used: 1-1600 μm (mean size = 89 μm), and 63-400 μm (mean size = 185 μm). All samples evolved similarly through four textural phases: phase 1—loose and cohesion-less particles; phase 2—particles sintered at contacts and surrounded by fully connected tortuous pore space of up to 40% porosity; phase 3—continuous matrix of partially coalesced particles that contain both isolated spherical vesicles and connected networks of larger, contorted vesicles; phase 4—dense glass with 2-5% fully isolated vesicles that are mainly spherical. Textures evolve faster at higher temperature and higher H2O pressure. Coarse samples sinter more slowly and contain fewer, larger vesicles when fully sintered. We quantify the sintering progress by measuring porosity as a function of experimental run-time, and find an excellent collapse of data when run-time is normalized by the sintering timescale {λ}_s=η \\overline{R}/σ , where η is melt viscosity, \\overline{R} is mean particle radius, and σ is melt-gas surface tension. Because timescales of diffusive H2O equilibration are generally fast compared to those of sintering, the relevant melt viscosity is calculated from the solubility H2O content at experimental temperature and pressure. We use our results to develop a framework for estimating ash sintering rates under shallow

  19. Mathematical model of Fischer-Tropsch catalyst pellet with pointed centers of synthesis

    Science.gov (United States)

    Derevich, I. V.; Fokina, A. Yu

    2017-11-01

    The productivity of Fischer-Tropsch reactors is determined by the efficiency of heat and mass transfer processes inside the catalyst pellets. To reduce the diffusion resistance, the pellet base is made porous. The porous structure of the granules causes a discrete arrangement of cobalt metallic microparticles whose size can reach tens of microns. The distance between these active centres significantly exceeds their characteristic size and the homogeneous catalyst model is incorrect. A mathematical model of heat and mass transfer processes inside a porous spherical pellet with localised active centres is proposed. The heat of the exothermic synthesis reaction is removed from the surface of the granule to the synthesis gas stream washing the catalyst pellet by heat transfer. The components of the synthesis gas enter the granule surface as a result of mass transfer. On the basis of the self-consistent field method, the values of the temperature and concentration of the synthesis gas components at the active centres were determined. It is shown that there is a critical temperature of the synthesis gas washing the granule, exceeding critical temperature leads to a substantial overheating of the active centres. In this case, the surface of the catalyst pellet is superheated slightly. The principal difference between the homogeneous and heterogeneous models in catalytic reactions is discussed.

  20. Sustained-release alginate-chitosan pellets prepared by melt pelletization technique.

    Science.gov (United States)

    Wong, Tin Wui; Nurulaini, Harjoh

    2012-12-01

    Alginate-chitosan pellets prepared by extrusion-spheronization technique exhibited fast drug dissolution. This study aimed to design sustained-release alginate pellets through rapid in situ matrix coacervation by chitosan during dissolution. Pellets made of alginate with chitosan and/or calcium acetate were prepared using solvent-free melt pelletization technique which prevented reaction between processing materials during agglomeration and allowed such reaction to occur only in dissolution phase. Drug release was retarded in pH 2.2 medium when pellets were formulated with calcium acetate or chitosan till a change in medium pH to 6.8. The sustained-release characteristics of calcium alginate pellets were attributed to pellet dispersion and rapid cross-linking by soluble Ca(2+) during dissolution. The slow drug release characteristics of alginate-chitosan pellets were attributed to polyelectrolyte complexation and pellet aggregation into swollen structures with reduced erosion. The drug release was, however, not retarded when both calcium acetate and chitosan coexisted in the same matrix as a result of chitosan shielding of Ca(2+) to initiate alginate cross-linkages and rapid in situ solvation of calcium acetate induced fast pellet dispersion and chitosan losses from matrix. Similar to calcium alginate pellets, alginate-chitosan pellets demonstrated sustained drug release property though via different mechanisms. Combination of alginate, chitosan and calcium acetate in the same matrix nevertheless failed to retard drug release via complementary drug release pattern.

  1. Complementary effects of torrefaction and co-pelletization: Energy consumption and characteristics of pellets.

    Science.gov (United States)

    Cao, Liang; Yuan, Xingzhong; Li, Hui; Li, Changzhu; Xiao, Zhihua; Jiang, Longbo; Huang, Binbin; Xiao, Zhihong; Chen, Xiaohong; Wang, Hou; Zeng, Guangming

    2015-06-01

    In this study, complementary of torrefaction and co-pelletization for biomass pellets production was investigated. Two kinds of biomass materials were torrefied and mixed with oil cake for co-pelletization. The energy consumption during pelletization and pellet characteristics including moisture absorption, pellet density, pellet strength and combustion characteristic, were evaluated. It was shown that torrefaction improved the characteristics of pellets with high heating values, low moisture absorption and well combustion characteristic. Furthermore, co-pelletization between torrefied biomass and cater bean cake can reduce several negative effects of torrefaction such as high energy consumption, low pellet density and strength. The optimal conditions for energy consumption and pellet strength were torrefied at 270°C and a blending with 15% castor bean cake for both biomass materials. The present study indicated that compelmentary performances of the torrefaction and co-pelletization with castor bean cake provide a promising alternative for fuel production from biomass and oil cake. Copyright © 2015. Published by Elsevier Ltd.

  2. Sintering behavior, microstructure and mechanical properties of vacuum sintered SiC/spinel nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guoqiang, E-mail: lguoqi1@lsu.edu [Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Department of Mechanical Engineering, Southern University, Baton Rouge, LA 70813 (United States); Tavangarian, Fariborz [Department of Mechanical and Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States)

    2014-12-05

    Highlights: • Bulk SiC/spinel nanocomposite was synthesized from talc, aluminum and graphite powders. • Sintering behavior and mechanical properties of SiC/spinel nanocomposite was studied. • The obtained bulk SiC/spinel nanocomposite had a mean crystallite size of about 34 nm. - Abstract: A mixture of SiC and spinel (MgAl{sub 2}O{sub 4}) nanopowder was prepared through the ball milling of talc, aluminum and graphite powder. The powder was uniaxially pressed into the form of pellets and the prepared specimens were annealed at various temperatures for different holding times. The prepared samples were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), nanoindentation test, cold crushing strength (CCS) test and Archimedes principle test. The obtained results showed that the hardness, CCS and bulk density did not follow the same trend at different temperatures due to the interaction among various parameters. The detailed investigation of microstructure, phase changes and experimental conditions revealed the mechanisms behind these behaviors. The best sample obtained after annealing at 1200 °C for 1 h in vacuum had the mean hardness of 1.6 GPa and the mean CCS of 118 MPa.

  3. Development and evaluation of omeprazole pellets fabricated by sieving-spheronization and extrusion - spheronization process.

    Science.gov (United States)

    Karim, Sabiha; Baie, Saringat H; Hay, Yuen Kah; Bukhari, Nadeem Irfan

    2014-05-01

    Pelletized dosage forms can be prepared by different methods which, in general, are time consuming and labor intensive. The current study was carried out to investigate the feasibility of preparing the spherical pellets of omeprazole by sieving-spheronization. An optimized formulation was also prepared by extrusion-spheronization process to compare the physical parameters between these two methods. The omeprazole pellets were consisted of microcrystalline cellulose, polyvinylpyrrolidone K 30, sodium lauryl sulphate and polyethylene glycol 6000. The omeprazole delay release system was developed by coating the prepared pellets with aqueous dispersion of Kollicoat 30 DP. The moisture content, spheronization speed and residence time found to influence the final properties of omeprazole pellets prepared by extrusion-spheronization and sieving-spheronization. The Mann-Whitney test revealed that both methods produced closely similar characteristics of the pellets in terms of, friability (p=0.553), flowability (p=0.677), hardness (p=0.103) and density (bulk, p=0.514, tapped, p=0.149) except particle size distribution (p=0.004). The percent drug release from the coated formulation prepared by sieving-spheronization and extrusion spheronization was observed to be 84.12 ± 1.10% and 82.67 ± 0.96%, respectively. Dissolution profiles of both formulations were similar as indicated by values of f1 and f2, 1.52 and 89.38, respectively. The coated formulation prepared by sieving-spheronization and commercial reference product, Zimore ® also showed similar dissolution profiles (f1=1.22, f2=91.52). The pellets could be prepared using sieving-spheronization. The process is simple, easy, less time- and labor-consuming and economical as compared to extrusion-spheronization process.

  4. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    ... involves compaction of polymeric powder under pressure and sintering of the preforms at temperature above its melting point. In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering temperatures and strength development.

  5. Factors governing microstructure development of Cr2O3-doped UO2 during sintering

    International Nuclear Information System (INIS)

    Bourgeois, L.; Dehaudt, Ph.; Lemaignan, C.; Hammou, A.

    2001-01-01

    Sintering and grain growth of compacted uranium dioxide powder pellets doped with Cr 2 O 3 were investigated at constant heating rates ranging from 75 to 500 K h -1 . The influence of parameters such as the oxygen potential of the sintering atmosphere and pellet green density on the final microstructure was studied. Dilatometric analysis and monitoring of microstructural development revealed a phenomenon of abnormal grain growth promoting densification. The existence of a eutectic between Cr and Cr 2 O 3 is also discussed. Grain growth does not appear to be widely affected by small differences in residual porosity, which is a function of green density, so that it is possible to propose a solubility limit for Cr 2 O 3 in stoichiometric UO 2 at 1700 deg. C. Examination of microstructural changes during annealing, with or without pore formers, showed the existence of limiting grain sizes for doped samples above the solubility limit. Lastly, experimental sintering conditions need to be checked in order to obtain reproducible results [fr

  6. Effect of porosity on thermal and electrical properties of polycrystalline bulk ZrN prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Adachi, Jun; Kurosaki, Ken; Uno, Masayoshi; Yamanaka, Shinsuke

    2007-01-01

    Two kinds of polycrystalline zirconium nitride (ZrN) pellets were prepared by a spark plasma sintering (SPS). Thermal and electrical properties were measured from room temperature to 1473 and 1000 K, respectively. Thermal expansion is almost independent of porosity. On the other hand, electrical and thermal conductivities systematically decreased with increasing porosity. Porosity dependences of electrical and thermal conductivities are studied through the Maxwell-Eucken's equation

  7. Master Sintering Surface: A practical approach to its construction and utilization for Spark Plasma Sintering prediction

    Directory of Open Access Journals (Sweden)

    Pouchly V.

    2012-01-01

    Full Text Available The sintering is a complex thermally activated process, thus any prediction of sintering behaviour is very welcome not only for industrial purposes. Presented paper shows the possibility of densification prediction based on concept of Master Sintering Surface (MSS for pressure assisted Spark Plasma Sintering (SPS. User friendly software for evaluation of the MSS is presented. The concept was used for densification prediction of alumina ceramics sintered by SPS.

  8. Evaluation of aluminosilicate glass sintering during differential scanning calorimetry

    International Nuclear Information System (INIS)

    Souza, Juliana Pereira de

    2015-01-01

    In this work a difference in the baseline in differential scanning calorimetry analyses, observed in a work where aluminosilicate glasses microspheres containing Ho were studied for application in selective internal radiotherapy as hepatocellular carcinoma treatment, was studied. The glasses with nominal composition 53,7 SiO 2 .10,5 Al 2 O 3 . 35,8 MgO in %mol were produced from traditional melting. The first obtained were milled and sieved in the range of 45 a 63 μm. The material was used to produce glass microspheres by the gravitational fall method. The glass powder and the microspheres were characterized by X ray fluorescence spectrometry, laser diffraction, X ray diffraction, differential scanning calorimetry, differential thermal analysis, thermogravimetry, mass spectrometry, and scanning electron microscopy. After the thermal analyses, pellets were formed in the crucibles and were analyzed by scanning electron microscopy, X ray diffraction, and He pycnometry. The difference in the baseline was associated to the viscous flow sintering process and happens because of the decrease in the detected heat flow due to the sample shrinkage. Other events as concurrent crystallization with the sintering process were also studied. (author)

  9. Spherical proton emitters

    International Nuclear Information System (INIS)

    Berg, S.; Semmes, P.B.; Nazarewicz, W.

    1997-01-01

    Various theoretical approaches to proton emission from spherical nuclei are investigated, and it is found that all the methods employed give very similar results. The calculated decay widths are found to be qualitatively insensitive to the parameters of the proton-nucleus potential, i.e., changing the potential parameters over a fairly large range typically changes the decay width by no more than a factor of ∼3. Proton half-lives of observed heavy proton emitters are, in general, well reproduced by spherical calculations with the spectroscopic factors calculated in the independent quasiparticle approximation. The quantitative agreement with experimental data obtained in our study requires that the parameters of the proton-nucleus potential be chosen carefully. It also suggests that deformed proton emitters will provide invaluable spectroscopic information on the angular momentum decomposition of single-proton orbitals in deformed nuclei. copyright 1997 The American Physical Society

  10. Spherical rhenium metal powder

    International Nuclear Information System (INIS)

    Leonhardt, T.; Moore, N.; Hamister, M.

    2001-01-01

    The development of a high-density, spherical rhenium powder (SReP) possessing excellent flow characteristics has enabled the use of advanced processing techniques for the manufacture of rhenium components. The techniques that were investigated were vacuum plasma spraying (VPS), direct-hot isostatic pressing (D-HIP), and various other traditional powder metallurgy processing methods of forming rhenium powder into near-net shaped components. The principal disadvantages of standard rhenium metal powder (RMP) for advanced consolidation applications include: poor flow characteristics; high oxygen content; and low and varying packing densities. SReP will lower costs, reduce processing times, and improve yields when manufacturing powder metallurgy rhenium components. The results of the powder characterization of spherical rhenium powder and the consolidation of the SReP are further discussed. (author)

  11. Sintering additives for zirconia ceramics

    International Nuclear Information System (INIS)

    Wu, S.

    1986-01-01

    This book is an overview of sintering science and its application to zirconia materials including CaO, MgO, and Y/sub 2/O/sub 3/-CeO/sub 2/ doped materials. This book is a reference for first-time exposure to zirconia materials technology, particularly densification

  12. Sintering additives for zirconia ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, S.

    1986-01-01

    This book is an overview of sintering science and its application to zirconia materials including CaO, MgO, and Y/sub 2/O/sub 3/-CeO/sub 2/ doped materials. This book is a reference for first-time exposure to zirconia materials technology, particularly densification.

  13. The Spherical Deformation Model

    DEFF Research Database (Denmark)

    Hobolth, Asgar

    2003-01-01

    Miller et al. (1994) describe a model for representing spatial objects with no obvious landmarks. Each object is represented by a global translation and a normal deformation of a sphere. The normal deformation is defined via the orthonormal spherical-harmonic basis. In this paper we analyse the s...... a single central section of the object. We use maximum-likelihood-based inference for this purpose and demonstrate the suggested methods on real data....

  14. Automation of Nuclear Fuel Pellet Quality Control

    International Nuclear Information System (INIS)

    Keyvan, Shahla; Song, Xiaolong

    2001-01-01

    It would be highly desirable to automate the pellet inspection process, which at the present time is done by humans using the naked eye for inspection. A prototype of an automated inspection system was developed. The system examines photographic images of pellets using various artificial intelligence techniques for image analysis and defect classification. The steps in the process are described

  15. Pellet production methods for fueling fusion devices

    International Nuclear Information System (INIS)

    Riedmueller, W.

    1980-10-01

    A review is given of the methods developed for producing and positioning hydrogen isotope pellets which are used for filling magnetic confinement machines. Composite pellets used in inertial confinement (i.e. laser fusion) experiments are not considered in this review. (orig.)

  16. Inspecting fuel pellets for nuclear reactor

    International Nuclear Information System (INIS)

    Wilks, R.S.; Sternheim, E.; Breakey, G.A.; Sturges, R.H.; Taleff, A.; Castner, R.P.

    1982-01-01

    An improved method of controlling the inspection, sorting and classifying of nuclear reactor fuel pellets, including a mechanical handling system and a computer controlled data processing system, is described. Having investigated the diameter, length, surface flaws and weights of the pellets, they are sorted accordingly and the relevant data are stored. (U.K.)

  17. Present status of laser fusion fuel pellet

    International Nuclear Information System (INIS)

    Nakai, Sadao; Mima, Kunioki; Norimatsu, Takayoshi; Takagi, Masaru.

    1986-01-01

    Accompanying the advance of pellet implosion experiment, the data base required for fuel pellet design has been steadily accumulated. The clarification of the physics related to the process of absorbing laser beam, energy transport, the generation of ablative pressure, the hydrodynamic mechanism of implosion, the energy transmission to fuel core and so on progressed, and the design data supported by these results are prepared. Based on the data base like this, the design of fuel pellets taking the optimization of implosion in consideration is carried out. The various fuel pellets designed in this way are tested for their effectiveness by implosion experiment. For this purpose, the high performance measurement of implosion and the high accuracy manufacture of fuel pellets become very important. In this paper, the present state of the research on the method of laser implosion, the example of pellet design and the law of proportion, the manufacturing techniques of the fuel pellets having various structures, the techniques dealing with tritium and so on is summarized, and the direction of future research and development is ascertained. At present, implosion experiment is carried out mostly by hanging a pellet target with a fiber of several μm diameter, but the fiber impairs the symmetry of implosion. The levitation techniques without contact is required. (Kako, I.)

  18. Hydrogen Pellet-Rotating Plasma Interaction

    DEFF Research Database (Denmark)

    Jørgensen, L. W.; Sillesen, Alfred Hegaard; Øster, Flemming

    1977-01-01

    Spectroscopic measurements on the interaction between solid hydrogen pellets and rotating plasmas are reported. It was found that the light emitted is specific to the pellet material, and that the velocity of the ablated H-atoms is of the order of l0^4 m/s. The investigation was carried out...

  19. Fabrication and characterization of absorber pellets for FFTF irradiation testing

    International Nuclear Information System (INIS)

    Wilson, C.N.; Hollenberg, G.W.

    1981-01-01

    Methods used for characterization of B 4 C powder and fabricated pellets are summarized. Fabrication techniques used at HEDL for absorber test pellets are reviewed and selected powder and pellet characterization data are presented

  20. The production of sinterable uranium dioxide from ammonium diuranate

    International Nuclear Information System (INIS)

    Fane, A.G.; Le Page, A.H.

    1975-02-01

    The development of a 0.13 m diameter pulsed fluidised bed reactor for the continuous production of sinterable uranium dioxide from ammonium diuranate is described. Calcination-reduction at 670 to 680 0 C produced powders with surface areas of 4 to 6 m 2 g -1 giving pellet densities in excess of 10.6 g cm -3 . Sinterability was relatively insensitive to changes in operating conditions, provided the availability of hydrogen was adequate, for gas flow rates in the range 0.95 to 1.4 l S -1 , pulse frequencies of 0.5 and 0.75 Hz and mean residence times of the solids from 0.6 to 1.4 hours. Sinterability was shown to be improved either by use of higher input concentrations, or by use of a secondary flow of hydrogen (about 5 per cent of input) fed into the powder collection system and flowing countercurrent to the UO 2 product. The maximum throughput of 17 kg UO 2 h -1 (0.6 hours mean residence time) required only 120 per cent of the stoichiometric requirement at an input concentration of 50 vol.per cent with secondary hydrogen flow. Results are given for studies of the kinetics of reduction of calcined ammonia diuranate in hydrogen and the residence time distribution of solids in a pulsed fluidised bed. Estimates based on these data suggested that the overall conversion of ammonium diuranate to uranium dioxide in the continuously operated pulsed fluidised bed reactor was in excess of 99 per cent. Continuous stabilisation of the UO 2 product was demonstrated at 12 kg h -1 or UO 2 , in a 0.15 m diameter glass stabiliser, using 10 vol.per cent air in nitrogen and a temperature of about 50 0 C. (author)

  1. Insights into the functionality of pelletization aid in pelletization by extrusion-spheronization.

    Science.gov (United States)

    Sarkar, Srimanta; Heng, Paul W S; Liew, Celine V

    2013-02-01

    This study investigated the particle sizes of pelletization aids from the different wet processing steps of extrusion-spheronization, and their influence on rheological and pellet properties. Three commercial microcrystalline cellulose (MCC) grades, three commercial cross-linked polyvinyl pyrrolidone (X-PVP) grades and two agglomerated X-PVP grades (prepared using roller compaction from two commercial fine particle size X-PVP grades) were used as pelletization aid. The pelletization aids were analyzed for their dry state particle size, individual particle size (sonicated powder dispersion in water) and in-process particle sizes (dispersions of processed materials from the different processing steps). No remarkable particle size changes were observed with the commercial X-PVP grades under the different conditions. The two fine X-PVP grades, but not the coarse grade, produced good quality pellets. MCC and agglomerated X-PVP grades exhibited spectacularly lower individual and in-process particle sizes, and produced good quality pellets although some of them had dry state particle sizes comparable to that of the commercial coarse X-PVP grade. In-process particle sizes of pelletization aids correlated strongly with the rheological and pellet properties of the pelletization aid:lactose (1:3) binary mixtures. These results demonstrated that small in-process particle size of pelletization aid is a critical requirement for successful pelletization by extrusion-spheronization.

  2. Underwater sympathetic detonation of pellet explosive

    Science.gov (United States)

    Kubota, Shiro; Saburi, Tei; Nagayama, Kunihito

    2017-06-01

    The underwater sympathetic detonation of pellet explosives was taken by high-speed photography. The diameter and the thickness of the pellet were 20 and 10 mm, respectively. The experimental system consists of the precise electric detonator, two grams of composition C4 booster and three pellets, and these were set in water tank. High-speed video camera, HPV-X made by Shimadzu was used with 10 Mfs. The underwater explosions of the precise electric detonator, the C4 booster and a pellet were also taken by high-speed photography to estimate the propagation processes of the underwater shock waves. Numerical simulation of the underwater sympathetic detonation of the pellet explosives was also carried out and compared with experiment.

  3. Quality of pellets from torrefied biomass and pellets torrefied at different temperatures

    DEFF Research Database (Denmark)

    Shang, Lei; Dahl, Jonas; Ahrenfeldt, Jesper

    Torrefaction is a mild thermal treatment in an inert atmosphere, which is known to increase the energy density of biomass on a mass basis (MJ kg-1). By combining the torrefaction process and pelletization the specific energy density on volume basis is further increased would thus allow for more...... cost effective volume limited transport. There are two ways of combining torrefaction and pelletization: pelletize torrefied biomass and torrefy regular pellets. The former is the one used for producing commercial torrefied pellets, while the latter one could be relevant for power plant which has...... facility to do torrefaction before co-firing. In this study, both ways were utilized to produce torrefied pellets. The quality of these pellets have been characterized for higher heating value (HHV), energy consumption during grinding, mechanical durability and equilibrium moisture content (EMC) under...

  4. Strain-enhanced sintering of iron powders

    Energy Technology Data Exchange (ETDEWEB)

    Amador, D.R.; Torralba, J.M. [Universidad Carlos III de Madrid, Departamento de Ciencias de Materiales e Ingenieria Metalurgica, Leganes, Madrid (Spain); Monge, M.A.; Pareja, R. [Universidad Carlos III de Madrid, Departamento de Fisica, Madrid (Spain)

    2005-02-01

    Sintering of ball-milled and un-milled Fe powders has been investigated using dilatometry, X-ray, density, and positron annihilation techniques. A considerable sintering enhancement is found in milled powders showing apparent activation energies that range between 0.44 and 0.80 eV/at. The positron annihilation results, combined with the evolution of the shrinkage rate with sintering temperature, indicate generation of lattice defects during the sintering process of milled and un-milled powders. The sintering enhancement is attributed to pipe diffusion along the core of moving dislocations in the presence of the vacancy excess produced by plastic deformation. Positron annihilation results do not reveal the presence of sintering-induced defects in un-milled powders sintered above 1200 K, the apparent activation energy being in good agreement with that for grain-boundary diffusion in {gamma}-Fe. (orig.)

  5. Improved critical current densities in bulk FeSe superconductor using ball milled powders and high temperature sintering

    Energy Technology Data Exchange (ETDEWEB)

    Muralidhar, M.; Furutani, K.; Murakami, M. [Graduate School of Science and Engineering, Superconducting Materials Laboratory, Shibaura Institute of Technology, Tokyo (Japan); Kumar, Dinesh; Rao, M.S. Ramachandra [Department of Physics, Nano Functional Materials Technology Centre and Materials Science Research Centre, Indian Institute of Technology Madras, Chennai (India); Koblischka, M.R. [Institute of Experimental Physics, Saarland University, Saarbruecken (Germany)

    2016-12-15

    The present study is investigating the effect of high temperature sintering combined with ball milled powders for the preparation of FeSe material via solid state sintering technique. The commercial powders of Fe (99.9% purity) and Se (99.9% purity) were mixed in a nominal ratio Fe:Se = 1:1 and thoroughly ground and ball-milled in a glove box during 6 h. Then, the powder mixture was pressed into pellets of 5 mm in diameter and 2 mm thickness using an uniaxial pressure of 100 MPa. The samples were sealed in quartz tubes and sintered at 600 C for 24 h. Then, the pellets were again thoroughly ground and ball-milled in the glove box and pressed into pellets, and the final sintering was performed at two different temperatures, namely at 900 C for 24 h and at 950 C for 24 h. X-ray diffraction results confirmed that both samples showed mainly of the β-FeSe with tetragonal structure. The temperature dependence of magnetization (M-T) curves revealed a sharp superconducting transition T{sub c,} {sub onset} = 8.16 K for the sample sintered at 900 C. Further, scanning electron microscopy observations proved that samples sintered at 900 C show a platelike grain structure with high density. As a result, improved irreversibility fields around 5 T and the critical current density (J{sub c}) values of 6252 A cm{sup -2} at 5 K and self-field are obtained. Furthermore, the normalized volume pinning force versus the reduced field plots indicated a peak position at 0.4 for the sample sintered at 900 C. Improved flux pinning and the high J{sub c} values are attributed to the textured microstructure of the material, produced by a combination of high temperature sintering and ball milling. (copyright 2016 The Authors. Phys. Status Solidi A published by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. The sintering blocking mechanism on the UO2-GD2O3 system. Part 1: the hypothesis of diffusion barrier

    International Nuclear Information System (INIS)

    Durazzo, M.; Frajndlich, E.U.C.; Riella, H.G.; Leal Neto, R.M.

    2004-01-01

    The direct incorporation of gadolinium into nuclear power reactor fuel is important to the reactivity compensation and adjustment of power distribution thus enabling longer fuel cycles and optimized fuel utilization. Dry mechanical blending of Gd 2 O 3 and UO 2 powders is commercially the most attractive process route due to its simplicity. Nevertheless, processing by this route leads to difficulties in getting sintered pellets with the minimum required density due to a sintering blocking mechanism. Regarding this, there s little published information and the explanations are focused on the formation of a low diffusivity Gd-rich (U, Gd)O 2 phase during sintering process which decreases pellets density. An attempt to understand the mechanism for this effect was done in this work. Experimental evidences indicated the existence of phases in the (U, Gd)O 2 system with structure different from the fluorite-type UO 2 structure. These new phases were found for Gd molar fractions higher than 0,5, which coincide with the lowering of both the sintered density and the interdiffusion coefficient. However, it has been also shown that these new phases cannot be itself the cause for the density decrease observed. (author)

  7. Finite element modelling and experiments for shaping nuclear powder pellets, application in technological tool developments to minimize damage during ejection, and geometrical tolerances

    International Nuclear Information System (INIS)

    Bayle, Jean-Philippe; Jorion, Frederic; Gobin, Francois; Moyer, Patrick; Delette, Gerard

    2012-01-01

    Die pressing and sintering processes are used in the fabrication of fuel with minor actinides. Perfect cylindrical sintered pellets must be directly obtained by the current processes with take into account the slight heterogeneities of the density, which ones are present in the green body as a result of frictional forces between powder and die. FEM of the compaction stage has been used to simulate the die pressing stage of nuclear oxide powders and to predict the green density distributions. An ejection method with or without profile correction in the die has been used to removing the die radially. (authors)

  8. Fundamentals of spherical array processing

    CERN Document Server

    Rafaely, Boaz

    2015-01-01

    This book provides a comprehensive introduction to the theory and practice of spherical microphone arrays. It is written for graduate students, researchers and engineers who work with spherical microphone arrays in a wide range of applications.   The first two chapters provide the reader with the necessary mathematical and physical background, including an introduction to the spherical Fourier transform and the formulation of plane-wave sound fields in the spherical harmonic domain. The third chapter covers the theory of spatial sampling, employed when selecting the positions of microphones to sample sound pressure functions in space. Subsequent chapters present various spherical array configurations, including the popular rigid-sphere-based configuration. Beamforming (spatial filtering) in the spherical harmonics domain, including axis-symmetric beamforming, and the performance measures of directivity index and white noise gain are introduced, and a range of optimal beamformers for spherical arrays, includi...

  9. Increase of thermal conductivity of uranium dioxide nuclear fuel pellets with beryllium oxide addition

    International Nuclear Information System (INIS)

    Camarano, D.M.; Mansur, F.A.; Santos, A.M.M. dos; Ferraz, W.B.

    2016-01-01

    The UO 2 fuel is one of the most used nuclear fuel in thermal reactors and has many advantages such as high melting point, chemical compatibility with cladding, etc. However, its thermal conductivity is relatively low, which leads to a premature degradation of the fuel pellets due to a high radial temperature gradient during reactor operation. An alternative to avoid this problem is to increase the thermal conductivity of the fuel pellets, by adding beryllium oxide (BeO). Pellets of UO 2 and UO 2 -BeO were obtained from a homogenized mixture of powders of UO 2 and BeO, containing 2% and 3% by weight of BeO and sintering at 1750 °C for 3 h under H 2 atmosphere after uniaxial pressing at 400 MPa. The pellet densities were obtained by xylol penetration-immersion method and the thermal diffusivity, specific heat and thermal conductivity were determined according to ASTM E-1461 at room temperature (25 deg C) and 100 deg C. The thermal diffusivity measurements were carried out employing the laser flash method. The thermal conductivity obtained at 25 deg C showed an increase with the addition of 2% and 3% of BeO corresponding to 19% and 28%, respectively. As for the measurements carried out at 100 deg C, there was an increase in the thermal conductivity for the same BeO contents of 20% and 31%. These values as a percentage of increased conductivity were obtained in relation to the UO 2 pellets. (author)

  10. Particle density determination of pellets and briquettes

    Energy Technology Data Exchange (ETDEWEB)

    Rabier, Fabienne; Temmerman, Michaeel [Centre wallon de Recherches agronomiques, Departement de Genie rural, CRA-W, Chaussee de Namur, 146, B 5030 Gembloux (Belgium); Boehm, Thorsten; Hartmann, Hans [Technologie und Foerderzentrum fuer Nachwachsende Rohstoffe, TFZ, Schulgasse 18, D 94315 Straubing (Germany); Daugbjerg Jensen, Peter [Forest and Landscape, The Royal Veterinary and Agricultural University, Rolighedsvej 23, DK 1958 Frederiksberg C (Denmark); Rathbauer, Josef [Bundesanstalt fuer Landtechnik, BLT, Rottenhauer Strasse,1 A 3250 Wieselburg (Austria); Carrasco, Juan; Fernandez, Miguel [Centro de investigaciones Energeticas, Medioambientales y Tecnologicas, CIEMAT, Avenida Complutense, 22 E 28040 Madrid (Spain)

    2006-11-15

    Several methods and procedures for the determination of particle density of pellets and briquettes were tested and evaluated. Round robin trials were organized involving five European laboratories, which measured the particle densities of 15 pellet and five briquette types. The test included stereometric methods, methods based on liquid displacement (hydrostatic and buoyancy) applying different procedures and one method based on solid displacement. From the results for both pellets and briquettes, it became clear that the application of a method based on either liquid or solid displacement (only tested on pellet samples) leads to an improved reproducibility compared to a stereometric method. For both, pellets and briquettes, the variability of measurements strongly depends on the fuel type itself. For briquettes, the three methods tested based on liquid displacement lead to similar results. A coating of the samples with paraffin did not improve the repeatability and the reproducibility. Determinations with pellets proved to be most reliable when the buoyancy method was applied using a wetting agent to reduce surface tensions without sample coating. This method gave the best values for repeatability and reproducibility, thus less replications are required to reach a given accuracy level. For wood pellets, the method based on solid displacement gave better values of repeatability, however, this instrument was tested at only one laboratory. (author)

  11. Pellet injector research and development at ORNL

    International Nuclear Information System (INIS)

    Combs, S.K.; Argo, B.E.; Baylor, L.R.; Cole, M.J.; Dyer, G.R.; Fehling, D.T.; Fisher, P.W.; Foster, C.A.; Foust, C.R.; Gouge, M.J.; Jernigan, T.C.; Langley, R.A.; Milora, S.L.; Qualls, A.L.; Schechter, E.; Sparks, D.O.; Tsai, C.C.; Wilgen, J.B.; Whealton, J.W.

    1993-01-01

    A variety of pellet injector designs have been developed at ORNL including single-shot guns that inject one pellet, multiple-shot guns that inject four and eight pellets, machine gun-types (single- and multiple-barrel) that can inject up to >100 pellets, and centrifugal accelerators (mechanical devices that are inherently capable of high repetition rates and long-pulse operation). With these devices, macroscopic pellets (1--6 mm in diameter) composed of hydrogen isotopes are typically accelerated to speeds of ∼1.0 to 2.0 km/s for injection into plasmas of experimental fusion devices. In the past few years, steady progress has been made at ORNL in the development and application of pellet injectors for fueling present-day and future fusion devices. In this paper, we briefly describe some research and development activities at ORNL, including: (1) two recent applications and a new one on large experimental fusion devices, (2) high-velocity pellet injector development, and (3) tritium injector research

  12. Pelletization of fine coals. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, K.V.S.

    1995-12-31

    Coal is one of the most abundant energy resources in the US with nearly 800 million tons of it being mined annually. Process and environmental demands for low-ash, low-sulfur coals and economic constraints for high productivity are leading the coal industry to use such modern mining methods as longwall mining and such newer coal processing techniques as froth flotation, oil agglomeration, chemical cleaning and synthetic fuel production. All these processes are faced with one common problem area--fine coals. Dealing effectively with these fine coals during handling, storage, transportation, and/or processing continues to be a challenge facing the industry. Agglomeration by the unit operation of pelletization consists of tumbling moist fines in drums or discs. Past experimental work and limited commercial practice have shown that pelletization can alleviate the problems associated with fine coals. However, it was recognized that there exists a serious need for delineating the fundamental principles of fine coal pelletization. Accordingly, a research program has been carried involving four specific topics: (i) experimental investigation of coal pelletization kinetics, (ii) understanding the surface principles of coal pelletization, (iii) modeling of coal pelletization processes, and (iv) simulation of fine coal pelletization circuits. This report summarizes the major findings and provides relevant details of the research effort.

  13. Co-pelletization of sewage sludge and biomass: the density and hardness of pellet.

    Science.gov (United States)

    Jiang, Longbo; Liang, Jie; Yuan, Xingzhong; Li, Hui; Li, Changzhu; Xiao, Zhihua; Huang, Huajun; Wang, Hou; Zeng, Guangming

    2014-08-01

    In the present study, the effects of process parameters on pellet properties were investigated for the co-pelletization of sludge and biomass materials. The relaxed pellet density and Meyer hardness of pellets were identified. Scanning electron microscopy, FT-IR spectra and chemical analysis were conducted to investigate the mechanisms of inter-particular adhesion bonding. Thermogravimetric analysis was applied to investigate the combustion characteristics. Results showed that the pellet density was increased with the parameters increasing, such as pressure, sludge ratio and temperature. High hardness pellets could be obtained at low pressure, temperature and biomass size. The optimal moisture content for co-pelletization was 10-15%. Moreover, the addition of sludge can reduce the diversity of pellet hardness caused by the heterogeneity of biomass. Increasing ratio of sludge in the pellet would slow down the release of volatile. Synergistic effects of protein and lignin can be the mechanism in the co-pelletization of sludge and biomass. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Synthesis of dense yttrium-stabilised hafnia pellets for nuclear applications by spark plasma sintering

    Czech Academy of Sciences Publication Activity Database

    Tyrpekl, V.; Holzhdauser, M.; Hein, H.; Vigier, J.F.; Somers, J.; Svora, Petr

    2014-01-01

    Roč. 454, 1-3 (2014), s. 398-404 ISSN 0022-3115 Institutional support: RVO:61388980 Keywords : Nuclear application * Sol-gel * Zirconia * Transmutation * Fabrication * Actinides Subject RIV: CA - Inorganic Chemistry Impact factor: 1.865, year: 2014

  15. Direct pelletization in a rotary processor controlled by torque measurements. II: effects of changes in the content of microcrystalline cellulose.

    Science.gov (United States)

    Kristensen, J; Schaefer, T; Kleinebudde, P

    2000-01-01

    In the present study we investigated the effect of changes in the content of microcrystalline cellulose (MCC) on a direct pelletization process in a rotary processor in which the liquid addition was terminated once a certain increase in torque was produced. Nine different mixtures of MCC and lactose with MCC contents varying from 10% to 100% (w/w) were pelletized using 6 different torque increase levels, and the changes in pellet characteristics were investigated. The pellet characteristics investigated were pellet shape, size, and size distribution as well as the water content of the pellets at the end of liquid addition. To produce spherical agglomerates with suitable characteristics in a reproducible way, a content of at least 20% (w/w) MCC was found necessary. Linear correlations were found between the MCC content and the water content and between the torque increase and the water content, showing that the torque increase is suitable to control the process. A higher torque increase or a higher MCC content was found to increase the water content independently of each other.

  16. Low Temperature Constrained Sintering of Cerium Gadolinium OxideFilms for Solid Oxide Fuel Cell Applications

    Energy Technology Data Exchange (ETDEWEB)

    Nicholas, Jason Dale [Univ. of California, Berkeley, CA (United States)

    2007-01-01

    Cerium gadolinium oxide (CGO) has been identified as an acceptable solid oxide fuel cell (SOFC) electrolyte at temperatures (500-700 C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, >1200 C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have complicated development of metal supported CGO SOFCs. The aim of this work was to find new sintering aids for Ce0.9Gd0.1O1.95, and to evaluate whether they could be used to produce dense, constrained Ce0.9Gd0.1O1.95 films at temperatures below 1000 C. To find the optimal sintering aid, Ce0.9Gd0.1O1.95 was doped with a variety of elements, of which lithium was found to be the most effective. Dilatometric studies indicated that by doping CGO with 3mol% lithium nitrate, it was possible to sinter pellets to a relative density of 98.5% at 800 C--a full one hundred degrees below the previous low temperature sintering record for CGO. Further, it was also found that a sintering aid's effectiveness could be explained in terms of its size, charge and high temperature mobility. A closer examination of lithium doped Ce0.9Gd0.1O1.95 indicated that lithium affects sintering by producing a Li2O-Gd2O3-CeO2 liquid at the CGO grain boundaries. Due to this liquid phase sintering, it was possible to produce dense, crack-free constrained films of CGO at the record low temperature of 950 C using cheap, colloidal spray deposition processes. This is the first time dense constrained CGO films have been produced below 1000 C and could help commercialize metal supported ceria based solid oxide fuel cells.

  17. Sintered wire cesium dispenser photocathode

    Science.gov (United States)

    Montgomery, Eric J; Ives, R. Lawrence; Falce, Louis R

    2014-03-04

    A photoelectric cathode has a work function lowering material such as cesium placed into an enclosure which couples a thermal energy from a heater to the work function lowering material. The enclosure directs the work function lowering material in vapor form through a low diffusion layer, through a free space layer, and through a uniform porosity layer, one side of which also forms a photoelectric cathode surface. The low diffusion layer may be formed from sintered powdered metal, such as tungsten, and the uniform porosity layer may be formed from wires which are sintered together to form pores between the wires which are continuous from the a back surface to a front surface which is also the photoelectric surface.

  18. Wood pellets : is it a reliable, sustainable, green energy option?

    International Nuclear Information System (INIS)

    Swaan, J.

    2006-01-01

    The Wood Pellet Association of Canada was formerly called the BC Pellet Fuel Manufacturers Association, and was renamed and re-organized in January 2006. The association serves as an advocate for the wood pellet industry in addition to conducting research projects. This power point presentation presented an overview of the wood pellet industry in North America and Europe. Canada's 23 pellet plants currently produce just over 1,000,000 tons of wood pellets annually. Pellet producers in the United States produce approximately 800,000 tons annually for the residential bagged market. There are currently 240 pellet plants in Europe, and district heating is the largest growth market for wood pellets in Europe. British Columbia (BC) pellet producers will ship 450,000 tons to European power plants in 2005. Wood pellet specifications were presented, with details of calorific values, moisture and ash contents. An outline of wood pellet production processes was provided. New pellet plants currently under construction were reviewed. Domestic, North American and overseas exports were discussed, along with production estimates for BC for the next 5 years. A chart of world production and consumption of wood pellets between 2000 to 2010 was presented. North American wood pellet technologies were described. The impact of the pine beetle infestation in BC on the wood pellet industry was evaluated, and a worldwide wood pellet production growth forecast was presented. Issues concerning off-gassing, emissions, and torrifracation were also discussed. tabs., figs

  19. Influence of Chemical Composition Variations on Densification During the Sintering of MOX Materials

    Science.gov (United States)

    Vaudez, S.; Marlot, C.; Lechelle, J.

    2016-06-01

    The mixed uranium-plutonium oxide (MOX) fabrication process is based on the preparation of UO2 and PuO2 powders. The mixture is pelletized before being sintered at 1973 K (1700 °C) in a reducing atmosphere of Ar/4pctH2/H2O. This paper shows how the densification of MOX fuel is affected during sintering by the moisture content of the gas, the plutonium content of the fuel, and the carbon impurity content in the raw materials. MOX densification can be monitored through dilatometric measurements and gas releases can be continuously analyzed during sintering in terms of their quantity and quality. Variations in the oxygen content in the fuel can be continuously recorded by coupling the dilatometer furnace with an oxygen measurement at the gas outlet. Any carbon-bearing species released, such as CO, can be also linked to densification phenomena when a gas chromatograph is installed at the outlet of the dilatometer. Recommendations on the choice of sintering atmosphere that best optimizes the fuel characteristics have been given on the basis of the results reported in this paper.

  20. Studies on the Sintering Behaviour of UO2-Gd2O3 Nuclear Fuel

    International Nuclear Information System (INIS)

    Durazzo, Michelangelo; Gracher Riella, Humberto

    2008-01-01

    The incorporation of gadolinium directly into nuclear power reactor fuel is important from the point of reactivity compensation and adjustment of power distribution enabling thus longer fuel cycles and optimized fuel utilization. The incorporation of Gd 2 O 3 powder directly into the UO 2 powder by dry mechanical blending is the most attractive process because of its simplicity. Nevertheless, processing by this method leads to difficulties while obtaining sintered pellets with the minimum required density. This is due to blockages during the sintering process. There is little information in published literature about the possible mechanism for this blockage and this is restricted to the hypothesis based on formation of a low diffusivity Gd rich (U,Gd)O 2 phase. Experimental evidences indicated the existence of phases in the (U,Gd)O 2 system with structure different from the fluorite type structure of UO 2 . The apparition of these new phases coincides with the lowering of the density after sintering and with the lowering of the interdiffusion coefficient. However, it has been shown experimentally that the sintering blockage phenomena cannot be explained on the basis of the formation of low diffusivity Gd rich (U,Gd)O 2 phases. The work was continued to investigate other possible blocking mechanism. (authors)

  1. Two-stage sintering of Al2O3 with polysiloxane

    International Nuclear Information System (INIS)

    Godoy, A.L.E.; Bressiani, A.H.A.

    2014-01-01

    The final stage of sintering involves grain growth which often is not desirable in the microstructure of structural ceramics and cutting tools. The ceramics derived from inorganic polymers allow the production of thermo mechanical materials due to their hardness and especially their excellent structural stability under aggressive environment. The aim of this study is to investigate the effect of two steps sintering process on density, microstructure and hardness of ceramics derived from the mixture alumina-polysiloxane (PMS). Alumina was ball-milled for 12, 24 and 48 hours. The alumina powder mean particle size was characterized by laser diffraction. It was added 10% wt of PMS. Pellets were prepared by die pressing and sintering at 1650°C/10min and 1550°C/1h. The sintered materials were characterized by evaluation of apparent density by helium picnometry, X-ray diffraction, scanning electron microscopy and Vickers indentation analysis for hardness determination. The specimens are composed by mullite and the best results were obtained with the addition of alumina milled for 48 hours. (author)

  2. Development of D2 Pellet Injectors

    DEFF Research Database (Denmark)

    Sørensen, H.; Andersen, S. A.; Nordskov Nielsen, A.

    1985-01-01

    A versatile extrusion-type pneumatic gun is described. The extrusion nozzle/gun barrel system can easily be exchanged to produce pellets in the diameter range 0.4—2.0 mm. Velocities in the range 0.1—1.35 km/s are obtained by adjusting the propeller gas pressure. It is proposed that this gun type...... can be used for larger pellets of 3.2 mm diameter as well and to accelerate such pellets by means of a high-pressure discharge....

  3. Nuclear tracks in sinterized gemstones

    International Nuclear Information System (INIS)

    Espinosa, G.; Rodriguez, L.V.; Golzarri, J.I.; Castano, V.M.

    1993-01-01

    The responses of sinterized gemstones to alpha particles attempt analyzed with the objective of finding new materials for SSNTD, and also to understand their interaction with radiation and the formation of tracks. In this work we present the results of the characterization of these materials as SSNTD. The micro structural changes observed by electron microscopy. The preparation, etching solution concentration, etching time and effects of temperature are discussed. (Author)

  4. Nano-sized ceramic particles of hydroxyapatite calcined with an anti-sintering agent.

    Science.gov (United States)

    Okada, Masahiro; Furuzono, Tsutomu

    2007-03-01

    Nano-sized crystals of calcined hydroxyapatite (HAp) having spherical morphologies were fabricated by calcination at 800 degrees C for 1 h with an anti-sintering agent surrounding the original HAp particles and the agent was subsequently removed by washing after calcination. The original HAp particles were prepared by a modified emulsion system, and surrounded with poly(acrylic acid, calcium salt) (PAA-Ca) by utilizing a precipitation reaction between calcium hydroxide and poly(acrylic acid) adsorbed on the HAp particle surfaces in an aqueous medium. In the case of calcination without PAA-Ca, micron-sized particles consisting of sintered polycrystals were mainly observed by scanning electron microscopy, indicating the calcination-induced sintering among the crystals. On the other hand, most of the crystals calcined with the anti-sintering agent were observed as isolated particles, and the mean size of the HAp crystals was around 80 nm. This result indicates that PAA-Ca and its thermally decomposed product, CaO, surrounding the HAp crystals could protect them against calcination-induced sintering during calcination at 800 degrees C. The HAp crystals calcined with PAA-Ca showed high crystallinity, and no other calcium phosphate phases could be detected.

  5. Microwave sintering of ceramic materials

    Science.gov (United States)

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  6. Production and ejection of solid hydrogen-isotope pellet (single pellet)

    International Nuclear Information System (INIS)

    Kasai, Satoshi; Hasegawa, Koichi; Miura, Yukitoshi; Ishibori, Ikuo

    1986-03-01

    The pneumatic gun type pellet injector (single pellet) has been constructed, which is basic type used at ORNL. The pellet in the carrier is 1.65 mm in diameter and 1.65 mm in length, and another is 1 mmD x 1 mmL. Hydrogen pellet velocity of about 900 m/s was observed at propellant gas (He) pressure of 14 kg/cm 2 . In the injection experiment into a plasma, typical velocity is 714 ∼ 833 m/s. These values are 80 ∼ 95 % of velocity calculated from the ideal gun model. The ejected pellet size is 71 ∼ 90 % of the hole size in the carrier disk (1.65 mmD x 1.65 mmL) and 46 ∼ 56 % (1 mmD x 1 mmL). The spread in the pellet trajectories is about 26 mm in diameter at a plasma center. (author)

  7. Effects of temperature variation and pellet dimension on settling velocity of fish feed pellets

    International Nuclear Information System (INIS)

    Shoaib, M.; Karim, A.; Naz, S.

    2013-01-01

    In the present research, investigation was carried out for variation in settling velocity of some pelletized fish pellets in relation to floating time (T1), diameter of pellets and temperature along with their water absorption properties under defined laboratory conditions. Among two diets of different ingredients DI and DII, it was observed that time for float (Tf) were greater at high range of temperature than lower range of temperature, for all tested pellets dimension (3 mm, 6 mm, 9 mm) of both diets DI and DII, while in case of settling velocity against high temperature range, lower values of settling velocities were recorded which shows an inverse relationship between them. On the other hand percent weight increments for diet DI were noted maximum for pellets size of 3,6 and 9 mm after 10 min of immersion i.e., 33.33, 55.55 and 38.46%, respectively, when compared to dry pellets. (author)

  8. Development of a novel pelletization technique through an extremely high-shear process using a mechanical powder processor to produce high-dose small core granules suitable for film coating.

    Science.gov (United States)

    Kondo, Keita; Kato, Aya; Niwa, Toshiyuki

    2015-04-10

    We established an extremely high-shear melt pelletization technique using a mechanical powder processor to produce high-dose granules smaller than 300 μm with properties suitable for film coating. A mixture of ethenzamide and polyethylene glycol (used as a low-melting binder) at various weight ratios was mechanically treated under various jacket temperatures. When the jacket temperature was set to 50 °C or greater, the product temperature reached the melting point of the binder, resulting in pelletization. The drug powder were pelletized with a small amount of binder to yield pellets of approximately 150 μm with a drug content of more than 90%. The mechanism of melt pelletization through ultrahigh shearing involves a series of nucleation, consolidation, coalescence and breakage stages. The power consumption profile corresponding to each stage in the pelletization revealed that pellets between 75 and 300 μm were effectively obtained at a large power consumption peak. The resultant pellets showed comparative sphericity and smoothness, and higher durability than commercial core granules for film coating. In conclusion, this study demonstrates that the extremely high-shear melt pelletization technique can give drug pellets with desirable properties as core particles for the coating process. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Pellet injection requirements for TORE SUPRA

    International Nuclear Information System (INIS)

    Lafferranderie, J.

    1986-01-01

    The main parameters of TORE SUPRA are outlined and pellet injection requirements to meet plasma density goals are discussed. Topics considered include plasma buildup, plasma refueling and penetration depth

  10. Kinetic depletion model for pellet ablation

    Energy Technology Data Exchange (ETDEWEB)

    Kuteev, Boris V. [State Technical Univ., St. Petersburg (Russian Federation)

    2001-11-01

    A kinetic model for depletion effect, which determines pellet ablation when the pellet passes a rational magnetic surface, is formulated. The model predicts a moderate decrease of the ablation rate compared with the earlier considered monoenergy versions [1, 2]. For typical T-10 conditions the ablation rate reduces by a reactor of 2.5 when the 1-mm pellet penetrates through the plasma center. A substantial deceleration of pellets -about 15% per centimeter of low shire rational q region; is predicted. Penetration for Low Field Side and High Field Side injections is considered taking into account modification of the electron distribution function by toroidal magnetic field. It is shown that Shafranov shift and toroidal effects yield the penetration length for HFS injection higher by a factor of 1.5. This fact should be taken into account when plasma-shielding effects on penetration are considered. (author)

  11. The effect of sintering temperature on electrical characteristics of Fe2TiO5/Nb2O5 ceramics for NTC thermistor

    Science.gov (United States)

    Wiendartun, Risdiana, Fitrilawati, Siregar, R. E.

    2016-02-01

    A study on the fabrication of Iron Titanium Oxide (Fe2TiO5) ceramics for negative temperature coefficient (NTC) thermistors has been carried out, in order to know the effect of sintering temperature on the electrical characteristic of 1.0 % mole Nb2O5 doped Fe2TiO5 ceramics.These ceramics were made by mixing commercial powders of Fe2O3, TiO2 and Nb2O5 with proportional composition to produce Fe2TiO5 based ceramic. The raw pellet was sintered at 1000 °C, 1100 °C and 1200 °C temperature for 2 hours in air. Analysis of the microstructure and crystal structure were performed by using a scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. XRD spectra showed that the crystal structure of all ceramics of Fe2TiO5 made at various sintering temperatures are orthorhombic. The SEM images showed that the grain size of pellet ceramics increase with increasing sintering temperatures. From electrical resistances data that was measured at temperature 30-300 °C, it is found that the value of thermistor constant (B), activation energy (Ea), thermistor sensitivity (α) and room temperature resistance (RRT) decreases with respect to the increasing of sintering temperature. The fabricated Fe2TiO5 ceramics have thermistor constants (B = 6394-6959 K). This can be applied as temperature sensor, and will fulfill the market requirement.

  12. Effect of magnesia on the compressive strength of pellets

    Science.gov (United States)

    Shen, Feng-man; Gao, Qiang-jian; Jiang, Xin; Wei, Guo; Zheng, Hai-yan

    2014-05-01

    The compressive strength of MgO-fluxed pellets was investigated before and after they were reduced. The porosity and pore size of green pellets, product pellets, and reduced pellets were analyzed to clarify how MgO affects the strength of the pellets. Experimental results show that when the MgO-bearing flux content in the pellets increases from 0.0wt% to 2.0wt%, the compressive strength of the pellets at ambient temperature decreases, but the compressive strength of the pellets after reduction increases. Therefore, the compressive strength of the pellets after reduction exhibits no certain positive correlation with that before reduction. The porosity and pore size of all the pellets (with different MgO contents) increase when the pellets are reduced. However, the increase in porosity of the MgO-fluxed pellets is relatively smaller than that of the traditional non-MgO-fluxed pellets, and the pore size range of the MgO-fluxed pellets is relatively narrower. The reduction swelling index (RSI) is a key factor for governing the compressive strength of the reduced pellets. An approximately reversed linear relation can be concluded that the lower the RSI, the greater the compressive strength of the reduced pellets is.

  13. Comparative Properties of Bamboo and Rice Straw Pellets

    Science.gov (United States)

    Xianmiao Liu; Zhijia Liu; Benhua Fei; Zhiyong Cai; Zehui Jiang; Xing' e Liu

    2013-01-01

    Bamboo is a potential major bio-energy resource. Tests were carried out to compare and evaluate the property of bamboo and rice straw pellets, rice straw being the other main source of biomass solid fuel in China. All physical properties of untreated bamboo pellets (UBP), untreated rice straw pellets (URP), carbonized bamboo pellets (CBP), and carbonized rice straw...

  14. In vitro and in vivo evaluation of floating riboflavin pellets developed using the melt pelletization process.

    Science.gov (United States)

    Hamdani, J; Goole, J; Moës, A J; Amighi, K

    2006-10-12

    Floating pellets were prepared using the melt pelletization process in a Mi-Pro high shear mixer (Pro-C-epT, Belgium). Formulations were based on a mixture of Compritol and Precirol as meltable binders and on the use of sodium bicarbonate and tartaric acid as gas-generating agents. Good floating abilities were obtained by using the gas-generating agents in both the inner matrix and the outer coating layer of the pellets. In vitro evaluation of floating capability was performed both by using the resultant weight apparatus and by counting floating pellets at the surface of beakers containing 0.1N HCl solution, in vivo evaluation of floating pellets capabilities was also performed. Riboflavin-containing floating pellets (FRF) were administered orally to nine healthy volunteers versus non-floating pellets (NFRF). Volunteers were divided in two groups, fasted group (n=4) 729 kcal and fed group (n=5) 1634 kcal as the total calorie intake on the testing day. An increase of urinary excretion of riboflavin was observed when the volunteers were dosed with the floating pellets, especially after feeding. As riboflavin has a narrow window of absorption in the upper part of small intestine, this phenomenon could be attributable to the gastric retention of floating pellets.

  15. Development of rapidly dissolving pellets within the Quality by Design approach.

    Science.gov (United States)

    Karatzas, A A; Politis, S N; Rekkas, D M

    2017-05-01

    The purpose of this study was the development of novel, fast disintegrating, effervescent pellets by employing the direct pelletization technique as a single step process. In line with the Quality by Design (QbD) regulatory framework, statistical experimental design was extensively applied to correlate significant formulation and process variables with the critical quality attributes of the product. Pellets were studied with regards to sphericity, size and size distribution. In contrast to the existing multiparticulate platforms, this development integrated only water-soluble excipients to facilitate the multifunctional use of the final dosage form. The application of a screening fractional factorial design augmented to a full factorial design set the roadmap for the rational selection of the composition and process parameters, revealing in parallel the positive contribution of the powder feeder on the CQAs, when the critical process and formulation factors were properly adjusted. The response surface methodology was exploited for the final process optimization phase, which allowed the construction of appropriate mathematical models connecting the input variables and the CQAs under study. The implementation of the desirability function, lead to the optimum formulation and process settings for the production of pellets with narrow size distribution and geometric mean diameter of approximately 800 μm. In conclusion, using a lean approach supported by design of experiments (DoE) techniques within the QbD framework, a novel multifunctional formulation platform has been developed.

  16. New automated pellet/powder assay system

    International Nuclear Information System (INIS)

    Olsen, R.N.

    1975-01-01

    This paper discusses an automated, high precision, pellet/ powder assay system. The system is an active assay system using a small isotopic neutron source and a coincidence detection system. The handling of the pellet powder samples has been automated and a programmable calculator has been integrated into the system to provide control and data analysis. The versatile system can assay uranium or plutonium in either active or passive modes

  17. Pelletization process of postproduction plant waste

    Science.gov (United States)

    Obidziński, S.

    2012-07-01

    The results of investigations on the influence of material, process, and construction parameters on the densification process and density of pellets received from different mixtures of tobacco and fine-grained waste of lemon balm are presented. The conducted research makes it possible to conclude that postproduction waste eg tobacco and lemon balm wastes can be successfully pelletized and used as an ecological, solid fuels.

  18. Spherical tokamak development in Brazil

    International Nuclear Information System (INIS)

    Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes

    2003-01-01

    The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  19. Spherical tokamak development in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Gerson Otto; Bosco, Edson Del; Ferreira, Julio Guimaraes [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma] (and others)

    2003-07-01

    The general characteristics of spherical tokamaks, or spherical tori, with a brief view of work in this area already performed or in progress at several institutions worldwide are described. The paper presents also the steps in the development of the ETE (Experiment Tokamak spheric) project, its research program, technical characteristics and operating conditions as of December, 2002 a the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  20. The ETE spherical Tokamak project

    International Nuclear Information System (INIS)

    Ludwig, Gerson Otto; Andrade, Maria Celia Ramos de; Barbosa, Luis Filipe Wiltgen

    1999-01-01

    This paper describes the general characteristics of spherical tokamaks, with a brief overview of work in the area of spherical torus already performed or in progress at several institutions. The paper presents also the historical development of the ETE (Spherical Tokamak Experiment) project, its research program, technical characteristics and status of construction in September, 1998 at the Associated plasma Laboratory (LAP) of the National Institute for Space Research (INPE) in Brazil. (author)

  1. The ETE spherical Tokamak project

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Gerson Otto; Andrade, Maria Celia Ramos de; Barbosa, Luis Filipe Wiltgen [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma] [and others]. E-mail: ludwig@plasma.inpe.br

    1999-07-01

    This paper describes the general characteristics of spherical tokamaks, with a brief overview of work in the area of spherical torus already performed or in progress at several institutions. The paper presents also the historical development of the ETE (Spherical Tokamak Experiment) project, its research program, technical characteristics and status of construction in September, 1998 at the Associated plasma Laboratory (LAP) of the National Institute for Space Research (INPE) in Brazil. (author)

  2. Dissolution test for homogeneity of mixed oxide fuel pellets

    International Nuclear Information System (INIS)

    Lerch, R.E.

    1979-08-01

    Experiments were performed to determine the relationship between fuel pellet homogeneity and pellet dissolubility. Although, in general, the amount of pellet residue decreased with increased homogeneity, as measured by the pellet figure of merit, the relationship was not absolute. Thus, all pellets with high figure of merit (excellent homogeneity) do not necessarily dissolve completely and all samples that dissolve completely do not necessarily have excellent homogeneity. It was therefore concluded that pellet dissolubility measurements could not be substituted for figure of merit determinations as a measurement of pellet homogeneity. 8 figures, 3 tables

  3. Titanium Powder Sintering in a Graphite Furnace and Mechanical Properties of Sintered Parts

    OpenAIRE

    Changzhou Yu; Peng Cao; Mark Ian Jones

    2017-01-01

    Recent accreditation of titanium powder products for commercial aircraft applications marks a milestone in titanium powder metallurgy. Currently, powder metallurgical titanium production primarily relies on vacuum sintering. This work reported on the feasibility of powder sintering in a non-vacuum furnace and the tensile properties of the as-sintered Ti. Specifically, we investigated atmospheric sintering of commercially pure (C.P.) titanium in a graphite furnace backfilled with argon and stu...

  4. Production of sintered alumina from powder; optimization of the sinterized parameters for the maximum mechanical resistence

    International Nuclear Information System (INIS)

    Rocha, J.C. da.

    1981-02-01

    Pure, sinterized alumina and the optimization of the parameters of sinterization in order to obtain the highest mechanical resistence are discussed. Test materials are sinterized from a fine powder of pure alumina (Al 2 O 3 ), α phase, at different temperatures and times, in air. The microstructures are analysed concerning porosity and grain size. Depending on the temperature or the time of sinterization, there is a maximum for the mechanical resistence. (A.R.H.) [pt

  5. Experiments with the Ignitor Pellet Injector (IPI)

    Science.gov (United States)

    Frattolillo, A.; Migliori, S.; Podda, S.; Bombarda, F.; Baylor, L. R.; Caughman, J. B. O.; Combs, S. K.; Foust, C.; Fehling, D.; McJill, J. M.; Meitner, S.; Roveta, G.

    2009-11-01

    The four barrel, two-stage pneumatic injector for the Ignitor experiment (IPI), built by ENEA and ORNL, has been tested in the course of three esperimental campaigns. The optimal shaping of the propellant pressure pulse to improve pellet acceleration is provided by specially designed Pulse Shaping Valves. These have been modified and tested on a new facility that allows operating pellet injector components in conditions close to those at which they will have to operate on the IPI. Fast closing (< 10 ms) valves drastically reduce the expansion volumes needed to remove the propellant gas at the end of the guiding tube. The four barrel (2.1, 2.2, 3.0 and 4.6 mm bores) pipe-gun cryostat is cooled down by a closed cycle refrigerator, and pellet diagnostics for measuring speed and mass of the pellets, as well as for capturing in-flight pictures of all four pellets were developed for this application. The final impact target is equipped with a shock accelerometer. The injector is designed to deliver pellets with velocities up to 4 km/s (2 km/s already achieved): the results of the latest experimental campaign will be reported.

  6. Tritium proof-of-principle pellet injector

    International Nuclear Information System (INIS)

    Fisher, P.W.

    1991-07-01

    The tritium proof-of-principle (TPOP) experiment was designed and built by Oak Ridge National Laboratory (ORNL) to demonstrate the formation and acceleration of the world's first tritium pellets for fueling of future fusion reactors. The experiment was first used to produce hydrogen and deuterium pellets at ORNL. It was then moved to the Tritium Systems Test Assembly at Los Alamos National Laboratory for the production of tritium pellets. The injector used in situ condensation to produce cylindrical pellets in a 1-m-long, 4-mm-ID barrel. A cryogenic 3 He separator, which was an integral part of the gun assembly, was capable of lowering 3 He levels in the feed gas to <0.005%. The experiment was housed to a glovebox for tritium containment. Nearly 1500 pellets were produced during the course of the experiment, and about a third of these were pure tritium or mixtures of deuterium and tritium. Over 100 kCi of tritium was processed through the experiment without incident. Tritium pellet velocities of 1400 m/s were achieved with high-pressure hydrogen propellant. The design, operation, and results of this experiment are summarized. 34 refs., 44 figs., 3 tabs

  7. Spherical grating spectrometers

    Science.gov (United States)

    O'Donoghue, Darragh; Clemens, J. Christopher

    2014-07-01

    We describe designs for spectrometers employing convex dispersers. The Offner spectrometer was the first such instrument; it has almost exclusively been employed on satellite platforms, and has had little impact on ground-based instruments. We have learned how to fabricate curved Volume Phase Holographic (VPH) gratings and, in contrast to the planar gratings of traditional spectrometers, describe how such devices can be used in optical/infrared spectrometers designed specifically for curved diffraction gratings. Volume Phase Holographic gratings are highly efficient compared to conventional surface relief gratings; they have become the disperser of choice in optical / NIR spectrometers. The advantage of spectrometers with curved VPH dispersers is the very small number of optical elements used (the simplest comprising a grating and a spherical mirror), as well as illumination of mirrors off axis, resulting in greater efficiency and reduction in size. We describe a "Half Offner" spectrometer, an even simpler version of the Offner spectrometer. We present an entirely novel design, the Spherical Transmission Grating Spectrometer (STGS), and discuss exemplary applications, including a design for a double-beam spectrometer without any requirement for a dichroic. This paradigm change in spectrometer design offers an alternative to all-refractive astronomical spectrometer designs, using expensive, fragile lens elements fabricated from CaF2 or even more exotic materials. The unobscured mirror layout avoids a major drawback of the previous generation of catadioptric spectrometer designs. We describe laboratory measurements of the efficiency and image quality of a curved VPH grating in a STGS design, demonstrating, simultaneously, efficiency comparable to planar VPH gratings along with good image quality. The stage is now set for construction of a prototype instrument with impressive performance.

  8. Model for the behaviour of thorium and uranium fuels at pelletization; Modelo para o comportamento de microesferas combustiveis de torio e uranio na peletizacao

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira Neto, Ricardo Alberto

    2000-11-15

    In this work, a model for the behaviour of thorium-uranium-mixed oxide microspheres in the pelletizing process is presented. This model was developed in a program whose objective was to demonstrate the viability of producing fissile material through the utilization of thorium in pressurized water reactors. This is important because it allows the saving of the strategic uranium reserves, and makes it possible the nuclear utilization of the large brazilian thorium reserves. The objective was to develop a model for optimizing physical properties of the microspheres, such as density, fracture strength and specific surface, so as to produce fuel pellets with microstructure, density, open porosity and impurity content, in accordance with the fuel specification. And, therefore, to adjust the sol-gel processing parameters in order to obtain these properties, and produce pellets with an optimized microstructure, adequate to a stable behaviour under irradiation. The model made it clear that to achieve this objective, it is necessary to produce microspheres with density and specific surface as small as possible. By changing the sol-gel processing parameters, microspheres with the desired properties were produced, and the model was experimentally verified by manufacturing fuel pellets with optimized microstructures, density, open porosity and impurity content, meeting the specifications for this new nuclear fuel for pressurized water reactors. Furthermore it was possible to obtain mathematical expressions that enables to calculate from the microspheres properties and the utilized compaction pressure, the sinter density that will be obtained in the sintered pellet and the necessary compaction pressure to reach the sintered density specified for the fuel. (author)

  9. Steam-treated wood pellets: Environmental and financial implications relative to fossil fuels and conventional pellets for electricity generation

    International Nuclear Information System (INIS)

    McKechnie, Jon; Saville, Brad; MacLean, Heather L.

    2016-01-01

    Highlights: • Steam-treated pellets can greatly reduce greenhouse gas emissions relative to coal. • Cost advantage is seen relative to conventional pellets. • Higher pellet cost is more than balanced by reduced retrofit capital requirements. • Low capacity factors further favour steam-treated pellets over conventional pellets. - Abstract: Steam-treated pellets can help to address technical barriers that limit the uptake of pellets as a fuel for electricity generation, but there is limited understanding of the cost and environmental impacts of their production and use. This study investigates life cycle environmental (greenhouse gas (GHG) and air pollutant emissions) and financial implications of electricity generation from steam-treated pellets, including fuel cycle activities (biomass supply, pellet production, and combustion) and retrofit infrastructure to enable 100% pellet firing at a generating station that previously used coal. Models are informed by operating experience of pellet manufacturers and generating stations utilising coal, steam-treated and conventional pellets. Results are compared with conventional pellets and fossil fuels in a case study of electricity generation in northwestern Ontario, Canada. Steam-treated pellet production has similar GHG impacts to conventional pellets as their higher biomass feedstock requirement is balanced by reduced process electricity consumption. GHG reductions of more than 90% relative to coal and ∼85% relative to natural gas (excluding retrofit infrastructure) could be obtained with both pellet options. Pellets can also reduce fuel cycle air pollutant emissions relative to coal by 30% (NOx), 97% (SOx), and 75% (PM 10 ). Lesser retrofit requirements for steam-treated pellets more than compensate for marginally higher pellet production costs, resulting in lower electricity production cost compared to conventional pellets ($0.14/kW h vs. $0.16/kW h). Impacts of retrofit infrastructure become increasingly

  10. Alternative sintering methods compared to conventional thermal sintering for inkjet printed silver nanoparticle ink

    NARCIS (Netherlands)

    Niittynen, J.; Abbel, R.; Mäntysalo, M.; Perelaer, J.; Schubert, U.S.; Lupo, D.

    2014-01-01

    In this contribution several alternative sintering methods are compared to traditional thermal sintering as high temperature and long process time of thermal sintering are increasing the costs of inkjet-printing and preventing the use of this technology in large scale manufacturing. Alternative

  11. Protocol for Ultralow-Temperature Ceramic Sintering: An Integration of Nanotechnology and the Cold Sintering Process.

    Science.gov (United States)

    Guo, Hanzheng; Baker, Amanda; Guo, Jing; Randall, Clive A

    2016-11-22

    The sintering process is an essential step in taking particulate materials into dense ceramic materials. Although a number of sintering techniques have emerged over the past few years, the sintering process is still performed at high temperatures. Here we establish a protocol to achieve dense ceramic solids at extremely low temperatures (sustainable manufacturing practices.

  12. Properties of millimetre wave sintered and oxygenated YBa2Cu3Ox bulk material

    International Nuclear Information System (INIS)

    Hunyar, C.

    1999-12-01

    High temperature superconductors are ceramic materials whose properties strongly depend on the techniques used for their production. The successful use of microwaves for the sintering of other oxidic ceramics suggests the examination of the advantages and disadvantages of that production technique for superconductors. For this purpose pellets of commercially available YBa 2 Cu 3 O x powder from the Solvay company were pressed and sintered by millimetre wave heating (30 GHz, generated in a gyrotron). In various experiments the sintering temperatures were varied between 920 C and 990 C, and the holding times between 15 min and 240 min. The densities of the pellets were measured by the Archimedes method and the material structure was examined with an optical microscope. A strong densification from 86 to 93% of theoretical density could be observed within 30 min at a holding temperature of 960 C. With sintering temperatures above 960 C no significant increase in density occurred. At 950 C, only minor grain growth could be observed, which increased up to 960 C temperature. At higher temperatures a mixture of small grains and crystallites of about 150 μm size established itself. CuO already present in the original powder started to melt along the grain boundaries where it acts as a limiting factor for grain growth. With millimetre wave sintering the same material densities could be achieved in less than one third of the time needed for conventional sintering processes. In addition the effects of millimetre wave heating on the oxygen diffusion in YBCO were investigated with several pairs of identical samples. The pairs were deoxygenated and subsequently oxygenated in an atmosphere of pure O 2 in a conventional tube furnace and by millimetre wave heating respectively. To compare the oxygen concentration of the samples, their specific surface resistance at room temperature, which correlates with the oxygen content, was measured in a cylindrical copper resonator with

  13. Density determination of sintered ceramic nuclear fuel materials

    International Nuclear Information System (INIS)

    Landspersky, H.; Medek, J.

    1980-01-01

    The feasibility was tested of using solids for pycnometric determination of the density of uranium dioxide-based sintered ceramic fuel materials manufactured by the sol-gel method in the shape of spherical particles of 0.7 to 1.0 mm in size and of particles smaller than 200 μm. For fine particles, this is the only usable method of determining their density which is a very important parameter of the fine fraction when it is employed for the manufacture of fuel elements by vibration compacting. The method consists in compacting a mixture of pycnometric material and dispersed particles of uranium dioxide, determining the size and weight of the compact, and in calculating the density of the material measured from the weight of the oxide sample in the mixture. (author)

  14. Effects of particle size and forming pressure on pore properties of Fe-Cr-Al porous metal by pressureless sintering

    Science.gov (United States)

    Koo, Bon-Uk; Yi, Yujeong; Lee, Minjeong; Kim, Byoung-Kee

    2017-03-01

    With increased hydrogen consumption in ammonia production, refining and synthesis, fuel cells and vehicle industries, development of the material components related to hydrogen production is becoming an important factor in industry growth. Porous metals for fabrication of hydrogen are commonly known for their relative excellence in terms of large area, lightness, lower heat capacity, high toughness, and permeability. Fe-Cr-Al alloys not only have high corrosion resistance, heat resistance, and chemical stability but also ductility, excellent mechanical properties. In order to control powder size and sintering temperature effects of Fe-Cr-Al porous metal fabrication, Fe-Cr-Al powder was classified into 25-35 μm, 35-45 μm, 45-75 μm using an auto shaking sieve machine and then classified Fe-Cr-Al powders were pressed into disk shapes using a uniaxial press machine and CIP. The pelletized Fe-Cr-Al specimens were sintered at various temperatures in high vacuum. Properties such as pore size, porosity, and air permeability were evaluated using perm-porosimetry. Microstructure and phase changes were observed with SEM and XRD. Porosity and relative density were proportionated to increasing sintering temperature. With sufficient sintering at increasing temperatures, the pore size is expected to be gradually reduced. Porosity decreased with increasing sintering temperature and gradually increased necking of the powder.

  15. Study of the influence of micro-structures and porosity of pellets alumina in the ultrasonic pulse in the frequency domain

    International Nuclear Information System (INIS)

    Costa, Antonio Mario Leal Martins

    2009-01-01

    This work is part of a study to the applicability of ultrasonic technique in the frequency domain for non-destructive characterization of ceramic pellets fuel, which is of great interest because of concern about the safety and efficacy in the nuclear industry. In this work it was analysed if there were changes in frequency spectrum, generated by the traveling of an ultrasonic pulse through ceramic pellets of aluminum oxide (Al 2 O 3 ). Using the ultrasonic technique in the frequency domain, together with micro-structural analysis of pellets by scanning electron microscope, it was possible to associate the characteristics of the material inspected with its respective frequency spectrum. The characterization was performed on 40 pellets alumina sintered in the temperatures of 1150, 1400, 1480, 1540 and 1580 deg C with porosities, as measured by the Archimedes method, ranging from 5.09% to 37.3%. The results show that the ultrasonic technique is effective in determining the micro-structure of ceramic alumina pellets and can be applied in the characterization of other porous materials in a production line, where the format of the frequency spectrum generated by the structure of the material may determine if the pellets belong the required specifications. (author)

  16. Effect of spherical porosity on co-fired dense/porous zirconia bi-layers cambering

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Marani, Debora; Kiebach, Wolff-Ragnar

    2018-01-01

    analyze the model case of dense taped of 8 mol% Y2O3-stabilized ZrO2 laminated on ca. 400 μ thick 3 mol% Y2O3 doped zirconia porous tapes, with homogenous spherical porosity of 13 vol%, 46 vol%, and 54 vol%. Sintering stress during densification is evaluated from the shrinkage rates and viscoelastic...

  17. Permeability model of sintered porous media: analysis and experiments

    Science.gov (United States)

    Flórez Mera, Juan Pablo; Chiamulera, Maria E.; Mantelli, Marcia B. H.

    2017-11-01

    In this paper, the permeability of porous media fabricated from copper powder sintering process was modeled and measured, aiming the use of the porosity as input parameter for the prediction of the permeability of sintering porous media. An expression relating the powder particle mean diameter with the permeability was obtained, based on an elementary porous media cell, which is physically represented by a duct formed by the arrangement of spherical particles forming a simple or orthorhombic packing. A circular duct with variable section was used to model the fluid flow within the porous media, where the concept of the hydraulic diameter was applied. Thus, the porous is modeled as a converging-diverging duct. The electrical circuit analogy was employed to determine two hydraulic resistances of the cell: based on the Navier-Stokes equation and on the Darcýs law. The hydraulic resistances are compared between themselves and an expression to determine the permeability as function of average particle diameter is obtained. The atomized copper powder was sifted to reduce the size dispersion of the particles. The porosities and permeabilities of sintered media fabricated from powders with particle mean diameters ranging from 20 to 200 microns were measured, by means of the image analysis method and using an experimental apparatus. The permeability data of a porous media, made of copper powder and saturated with distilled water, was used to compare with the permeability model. Permeability literature models, which considers that powder particles have the same diameter and include porosity data as input parameter, were compared with the present model and experimental data. This comparison showed to be quite good.

  18. Ultrasonic vibration-assisted (UV-A) pelleting of wheat straw: a constitutive model for pellet density.

    Science.gov (United States)

    Song, Xiaoxu; Zhang, Meng; Pei, Z J; Wang, Donghai

    2015-07-01

    Ultrasonic vibration-assisted (UV-A) pelleting can increase cellulosic biomass density and reduce biomass handling and transportation costs in cellulosic biofuel manufacturing. Effects of input variables on pellet density in UV-A pelleting have been studied experimentally. However, there are no reports on modeling of pellet density in UV-A pelleting. Furthermore, in the literature, most reported density models in other pelleting methods of biomass are empirical. This paper presents a constitutive model to predict pellet density in UV-A pelleting. With the predictive model, relations between input variables (ultrasonic power and pelleting pressure) and pellet density are predicted. The predicted relations are compared with those determined experimentally in the literature. Model predictions agree well with reported experimental results. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Steady-state thermal-hydraulic analysis of the pellet-bed reactor for nuclear thermal propulsion

    International Nuclear Information System (INIS)

    El-Genk, M.S.; Morley, N.J.; Yang, J.Y.

    1992-01-01

    The pellet-bed reactor (PBR) for nuclear thermal propulsion is a hydrogen-cooled, BeO-reflected, fast reactor, consisting of an annular core region filled with randomly packed, spherical fuel pellets. The fuel pellets in the PBR are self-supported, eliminating the need for internal core structure, which simplifies the core design and reduces the size and mass of the reactor. Each spherical fuel pellet is composed of hundreds of fuel microspheres embedded in a zirconium carbide (ZrC) matrix. Each fuel microsphere is composed of a UC-NbC fuel kernel surrounded by two consecutive layers of the NbC and ZrC. Gaseous hydrogen serves both as core coolant and as the propellant for the PBR rocket engine. The cold hydrogen flows axially down the inlet channel situated between the core and the external BeO reflector and radially through the orifices in the cold frit, the core, and the orifices in the hot frit. Finally, the hot hydrogen flows axially out the central channel and exits through converging-diverging nozzle. A thermal-hydraulic analysis of the PBR core was performed with an emphasis on optimizing the size and axial distribution of the orifices in the hot and cold frits to ensure that hot spots would not develop in the core during full-power operation. Also investigated was the validity of the assumptions of neglecting the axial conduction and axial cross flow in the core

  20. Miniaturization of Spherical Magnetodielectric Antennas

    DEFF Research Database (Denmark)

    Hansen, Troels Vejle

    ; Arbitrary order of the spherical wave, arbitrary radius of the spherical antenna, as well as arbitrarily large core permeability and/or permittivity, given an inversely proportional frequency variation of the imaginary part(s) and an arbitrary dispersion of the real part(s) - thus describing both lossless...

  1. Development and evaluation of prolonged release pellets obtained by the melt pelletization process.

    Science.gov (United States)

    Hamdani, Jamila; Moës, André J; Amighi, Karim

    2002-10-01

    This study was performed in order to evaluate the possibility of obtaining prolonged release matrix pellets by a melt pelletization process in a laboratory high shear mixer (Mi-Pro, Pro-C-epT). Phenylephrine hydrochloride pellet formulations based on lactose 450 mesh and a mixture of Compritol 888 and Precirol ATO 5 as melting binders were evaluated. The fatty binder content of pellets was substantially increased (from 18 to 80% w/w). The effects of jacket temperature, massing time (MT) and impeller speed (IS) on the pellet characteristics were investigated. It was shown that pellets of narrow size distribution can be produced by using an IS of 800 rpm, a chopper speed of 4000 rpm and a MT of 8 min. On the other hand, the applicability of this technique for the production of sustained-release pellets using ciprofloxacin hydrochloride, ketoprofen and theophylline as less water soluble model drugs than phenylephrine hydrochloride was also studied. This study demonstrated that formulations based on an appropriate mixture of Precirol and Compritol can be used to produce in a short time prolonged release pellets for very hydrosoluble drugs like phenylephrine hydrochloride as well as for the other drugs tested.

  2. Elaboration of pellets of LiF: Mg, Cu, P and its dosimetric properties; Elaboracion de pastillas de LiF: Mg, Cu, P y sus propiedades dosimetricas

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez C, A.; Gonzalez M, P.R.; Azorin N, J

    1991-03-15

    The LiF: Mg, Cu, P is at the moment in the entire world one of the TL materials of more interest, by its equivalence with the tissue, as well as for its high sensitivity, which is 25 to 35 times greater than of the TLD-100 of Harshaw (USA). In our laboratory dosemeters of this material have been developed in form of sinterized pellets. The importance of these new dosemeters in pellet form is due to that in this form its manipulation is facilitated. Due to its high sensitivity, these dosemeters result to be those but appropriate to measure the ionizing radiations, in intervals of extremely low dose. In this report the method of elaboration of the pellets, as well as its main dosimetric characteristics are presented. (Author)

  3. Gadolinium doped ceria interlayers for Solid Oxide Fuel Cells cathodes: Enhanced reactivity with sintering aids (Li, Cu, Zn), and improved densification by infiltration

    Science.gov (United States)

    Nicollet, Clement; Waxin, Jenny; Dupeyron, Thomas; Flura, Aurélien; Heintz, Jean-Marc; Ouweltjes, Jan Pieter; Piccardo, Paolo; Rougier, Aline; Grenier, Jean-Claude; Bassat, Jean-Marc

    2017-12-01

    This paper reports the study of the densification of 20% Gd doped ceria (Ce0.8Gd0.2O1.9 (GDC)) interlayers in SOFC cathodes through two different routes: the well-known addition of sintering elements, and an innovative densification process by infiltration. First, Li, Cu, and Zn nitrates were added to GDC powders. The effect of these additives on the densification was studied by dilatometry on pellets, and show a large decrease of the sintering temperature from 1330 °C (pure GDC), down to 1080 °C, 950 °C, and 930 °C for Zn, Cu, and Li addition, respectively. However, this promising result does not apply to screen-printed layers, which are more porous than pellets and in which the shrinkage is constrained by the substrate. The second approach consists in preparing a pre-sintered GDC layer, which is subsequently infiltrated with Ce and Gd nitrates and sintered at 1250 °C to increase its density. Such an approach results in highly dense GDC interlayers. Using La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) as electrode, the influence of the interlayers on the cathode performance was studied. The addition of sintering aids dramatically increases the cell resistances, most likely because the additives increase the reactivity between GDC and either Yttria Stabilized Zirconia (YSZ) or LSCF, thus losing the expected benefit related to the decrease of sintering temperatures. The interlayers prepared by infiltration do not induce additional resistances in the cell, which results in power densities of single cells 40-50% higher than those of cells prepared with commercial GDC interlayers, making this approach a valuable alternative to sintering aids.

  4. Ionic Conductivity and Air Stability of Al-Doped Li₇La₃Zr₂O₁₂ Sintered in Alumina and Pt Crucibles.

    Science.gov (United States)

    Xia, Wenhao; Xu, Biyi; Duan, Huanan; Guo, Yiping; Kang, Hongmei; Li, Hua; Liu, Hezhou

    2016-03-02

    Li7La3Zr2O12 (LLZO) is a promising electrolyte material for all-solid-state battery due to its high ionic conductivity and good stability with metallic lithium. In this article, we studied the effect of crucibles on the ionic conductivity and air stability by synthesizing 0.25Al doped LLZO pellets in Pt crucibles and alumina crucibles, respectively. The results show that the composition and microstructure of the pellets play important roles influencing the ionic conductivity, relative density, and air stability. Specifically, the 0.25Al-LLZO pellets sintered in Pt crucibles exhibit a high relative density (∼96%) and high ionic conductivity (4.48 × 10(-4) S cm(-1)). The ionic conductivity maintains 3.6 × 10(-4) S cm(-1) after 3-month air exposure. In contrast, the ionic conductivity of the pellets from alumina crucibles is about 1.81 × 10(-4) S cm(-1) and drops to 2.39 × 10(-5) S cm(-1) 3 months later. The large grains and the reduced grain boundaries in the pellets sintered in Pt crucibles are favorable to obtain high ionic conductivity and good air stability. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy results suggest that the formation of Li2CO3 on the pellet surface is probably another main reason, which is also closely related to the relative density and the amount of grain boundary within the pellets. This work stresses the importance of synthesis parameters, crucibles included, to obtain the LLZO electrolyte with high ionic conductivity and good air stability.

  5. Master sintering curves of two different alumina powder compacts

    Directory of Open Access Journals (Sweden)

    Vaclav Pouchly

    2009-12-01

    Full Text Available Concept of Master Sintering Curve is a strong tool for optimizing sintering schedule. The sintering behaviour can be predicted, and sintering activation energy can be calculated with the help of few dilatometric measurements. In this paper an automatic procedure was used to calculate Master Sintering Curves of two different alumina compacts. The sintering activation energies were determined as 640 kJ/mol for alumina with particle size of 240 nm, respective 770 kJ/mol for alumina with particle size of 110 nm. The possibility to predict sintering behaviour with the help of Master Sintering Curve was verified.

  6. Sintering characteristics of nano-ceramic coatings

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Popma, R.

    2003-01-01

    This paper concentrates on sintering characteristics of nano-sized ceramic SiO2 particles. The sintering process is studied as a function of temperature using a conventional furnace and using a laser beam. The underlying idea is to combine the nanoceramic sol-gel concept with inkjet technology and

  7. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    In firing of products by conventionally sintered process, SiC grain gets oxidized producing SiO2 (∼ 32 wt%) and deteriorates the quality of the product substantially. Partially sintered silicon carbide by such a method is a useful material for a varieties of applications ranging from kiln furniture to membrane material.

  8. Kinetic analysis of boron carbide sintering

    International Nuclear Information System (INIS)

    Borchert, W.; Kerler, A.R.

    1975-01-01

    The kinetics of the sintering of boron carbide were investigated by shrinkage measurements with a high-temperature dilatometer under argon atmosphere in dependence on temperature, grain size, and pressure. The activation energies and the reaction mechanisms of the different stages of sintering were determined. (orig.) [de

  9. Electro sinter forging of titanium disks

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin; Bay, Niels Oluf

    Electro sinter forging (ESF) is a new sintering process based on the principle of electrical Joule heating. In the present work, middle frequency direct current (MFDC) was flowing through the powder compact, which was under mechanical pressure. The main parameters are the high electrical current,...

  10. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    Abstract. Ultra high molecular weight polyethylene (UHMWPE) is a high performance polymer having low coefficient of friction, good abrasion resistance, good chemical ... In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering ...

  11. Sintering of zirconia in high-pressure

    International Nuclear Information System (INIS)

    Kunrath, A.O.; Strohaecker, T.R.; Pereira, A.S.; Jornada, J.A.H. da; Piermarini, G.J.

    1989-01-01

    A systematic study about the sintering of zirconia hyperfines powders in high-pressure is presented. The differents conditions effect of sintering in microstructure and in hardness and tenacity properties of zirconia samples with a very fine grain is also studied. (C.G.C.) [pt

  12. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Tikare, V.

    A numerical model able to simulate solid state constrained sintering of a powder compact is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element (FE) method for calculating stresses on a microstructural level. The microstructural respon...

  13. Modeling the Microstructural Evolution During Constrained Sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Pryds, Nini

    2015-01-01

    A numerical model able to simulate solid-state constrained sintering is presented. The model couples an existing kinetic Monte Carlo model for free sintering with a finite element model (FEM) for calculating stresses on a microstructural level. The microstructural response to the local stress as ...

  14. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    Unknown

    Central Glass and Ceramic Research Institute, Kolkata 700 032, India. Abstract. The present work deals with the sintering of ... recently become an attractive area of research and deve- lopment. The major advantages of ... without the usage of sintering aids (Lee and Case 1999;. Goldstein et al 1999). Several studies have ...

  15. THE POLARIZING EFFECTS IN SINTERED KAOLIN

    African Journals Online (AJOL)

    compacted and sintered density of the ceramic have been studied, and a density — pressure relationship for before- and after-sintering conditions obtained. INTRODUCTION. Ceramics have been known to mankind for thousands of years, and have been used in construction materials. In many applications, ceramics have.

  16. A Comparative Study of the Sintering Behavior of Pure and Manganese-Substituted Hydroxyapatite

    Directory of Open Access Journals (Sweden)

    Michael Zilm

    2015-09-01

    Full Text Available Hydroxyapatite (HA is a widely studied biomaterial for its similar chemical composition to bone and its osteoconductive properties. The crystal structure of HA is flexible, allowing for a wide range of substitutions which can alter bioactivity, biodegradation, and mechanical properties of the substituted apatite. The thermal stability of a substituted apatite is an indication of its biodegradation in vivo. In this study, we investigated the thermal stability and mechanical properties of manganese-substituted hydroxyapatite (MnHA as it is reported that manganese can enhance cell attachment compared to pure HA. Pure HA and MnHA pellets were sintered over the following temperature ranges: 900 to 1300 °C and 700 to 1300 °C respectively. The sintered pellets were characterized via density measurements, mechanical testing, X-ray diffraction, and field emission electron microscopy. It was found that MnHA was less stable than HA decomposing around 800 °C compared to 1200 °C for HA. The flexural strength of MnHA was weaker than HA due to the decomposition of MnHA at a significantly lower temperature of 800 °C compared to 1100 °C for HA. The low thermal stability of MnHA suggests that a faster in vivo dissolution rate compared to pure HA is expected.

  17. The Influence of Sintering Temperature of Reactive Sintered (Ti, MoC-Ni Cermets

    Directory of Open Access Journals (Sweden)

    Marek Jõeleht

    2015-09-01

    Full Text Available Titanium-molybdenum carbide nickel cermets ((Ti, MoC-Ni were produced using high energy milling and reactive sintering process. Compared to conventional TiC-NiMo cermet sintering the parameters for reactive sintered cermets vary since additional processes are present such as carbide synthesis. Therefore, it is essential to acquire information about the suitable sintering regime for reactive sintered cermets. One of the key parameters is the final sintering temperature when the liquid binder Ni forms the final matrix and vacancies inside the material are removed. The influence of the final sintering temperature is analyzed by scanning electron microscopy. Mechanical properties of the material are characterized by transverse rupture strength, hardness and fracture toughness.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7179

  18. Technology and distribution of pellets. Experience about the European network on wood pellets

    International Nuclear Information System (INIS)

    Rapp, S.W.

    1999-01-01

    Wood pellets might become the most important alternative to fossil fuels in the near future. As a bio-fuel it has the following characteristics: heat value, min 4.7 kWh/kg; ash fraction less than 1.0 vol. %; humidity less than 10 vol. %; diameter (rod shaped) min 6 mm and volumetric weight about 650 kg/m 3 . About 2.1 t pellets substitute 1000 l fuel oil. Sweden and Austria have more than 15 year experience in using wood pellets, followed by Germany. They are an environmentally friendly alternative for private houses, for district heating plants and especially suitable for densely built-up and inhabited areas. Having high energy density they can be transported to the areas with high energy requirements. Among their advantages are: low humidity, easy transport and storage, can be produced by renewable raw materials and provide new local jobs, fit for renewable energy systems with closed cycle. Disadvantages include: relatively more expensive for private houses compared to oil and gas and necessity of two times larger storage space than oil. Wood pellets are produced by all kind of paper waste and wood wastes from industry. They are especially suitable for small boiler plants and the oil burner can be replaced by a pellet burner in the same boiler. The leading producer of wood pellets is Sweden, of pellet stoves - USA. Pellet stoves, pellet burners and pellet boilers both for private houses and for heating plants are manufactured also in Sweden, Denmark,Finland, Germany, Austria and Ireland

  19. Studies on preparation of aceclofenac pellets by centrifugal granulator

    Directory of Open Access Journals (Sweden)

    Zibin GAO

    Full Text Available To prepare aceclofenac pellets by centrifugal granulation. Using 90~100 g of starch pellets as the core pellets,100 g of aceclofenac mixed with 50 g of microcrystalline cellulose(MCC and 4 g talc, methyl cellulose (HPMC as binder,the aceclofenac pellets were prepared by centrifugal granulation .And evaluate the quality of the pellets. The aceclofenac pellets had high yield and less losses,the pellets had a partical size of 0.70~0.88 mm(18~24 mesh)and had uniform particle size .the moisture ,drug content and dissolution meet the requirement . Aceclofenac pellets were prepared by the process of centrifugal granulation .The preparation prescription and process parameters were optimized by single factor method .and the pellets meet the standard requirements.

  20. Pelletized waste form demonstration program, October 1980-March 1981

    International Nuclear Information System (INIS)

    Lewis, E.L.; Herbert, R.F. Jr.

    1981-01-01

    During the last six months, performance testing of waste/cement pellets was continued. These evaluations included leachability tests and compressive strength tests of cold soil/cement pellets of various compositions. Fractional leach rates (g/cm 2 /day) after 21 months of testing were, in all cases -5 g/cm 2 /day (Mound Acceptance Value). Based upon these recent data, the pressed waste/cement pellets appeared to be a suitable matrix for the immobilization of low-level transuranic wastes. The installation of the Carver custom pellet press was completed. Plutonium-238 contaminated (< 100 nCi/g) ash/cement pellets were produced at a rate of 360 pellets/hr. Pellets of two different compositions were produced, 50% ash/50% cement and 65% ash/35% cement. The compressive strength of sample pellets was slightly lower than expected. Static MCC-1 leachability testing as well as long-term radiolysis testing of sample pellets are scheduled

  1. Pellet injector research and development at ORNL

    International Nuclear Information System (INIS)

    Combs, S.K.; Barber, G.C.; Baylor, L.R.

    1994-01-01

    Oak Ridge National Laboratory has been developing pellet injectors for plasma fueling experiments on magnetic confinement devices for more than 15 years. Recent major applications of the ORNL development program include (1) a tritium-compatible four-shot pneumatic injector for the Tokamak Fusion Test Reactor, (2) a centrifuge pellet injector for the Tore Supra tokamak, and most recently (3) a three-barrel repeating pneumatic injector for the DIII-D tokamak. In addition to applications, ORNL is developing advanced technologies, including high-speed pellet injectors, tritium injectors, and long-pulse pellet feed systems. The high-speed research involves a collaboration between ORNL and ENEA-Frascati in the development of a repeating two-stage light gas gun based on an extrusion-type pellet feed system. Construction of a new tritium-compatible, extruder-based repeating pneumatic injector (8-mm-diam) is complete and will replace the pipe gun in the original tritium proof-of-principle experiment. The development of a steady-state feed system in which three standard extruders operate in tandem is under way. These research and development activities are relevant to the International Thermonuclear Experimental Reactor and are briefly described in this paper

  2. Sintered ceramics having controlled density and porosity

    International Nuclear Information System (INIS)

    Brassfield, H.C.; DeHollander, W.R.; Nivas, Y.

    1980-01-01

    A new method was developed for sintering ceramic uranium dioxide powders, in which ammonium oxalate is admixed with the powder prior to being pressed into a cylindrical green body, so that the end-point density of the final nuclear-reactor fuel product can be controlled. When the green body is heated, the ammonium oxalate decomposes and leaves discrete porosity in the sintered body, which corresponds to the ammonium oxalate regions in the green body. Thus the end-point density of the sintered body is a function of the amount of ammonium oxalate added. The final density of the sintered product is about 90-97% of the theoretical. The addition of ammonium oxalate also allows control of the pore size and distribution throughout the fuel. The process leaves substantially no impurities in the sintered strucuture. (DN)

  3. Development of mesalazine pellets coated with methacrylic-derived polymer

    Directory of Open Access Journals (Sweden)

    Simone Cristina Déo

    2011-03-01

    Full Text Available Mesalazine (5-ASA is the standard drug for the treatment of inflammatory bowel disease (IBD due to its local effect on intestinal and colonic mucosa. The effective and safe treatment of this disease requires more efficient delivery of the active substance to its site of action. The focus of this study was the use of multiparticulate systems, a modified release form in which the drug is divided into several functional subunits of release in the form of granules or pellets. When these forms are administered, they are rapidly disintegrated, distributing their content throughout the gastrointestinal tract. The aim of this study was to develop and evaluate a multiparticulate system consisting of pellets coated with polymer for pH-dependent release, derived from methacrylic acid and incorporated into the tablet dosage form of mesalazine as a model drug. The extrusion-spheronisation technique was used, resulting in smooth and spherical pellets with uniform size distribution, which were coated in fluidized bed using Opadry® Enteric 94K28327 containing Eudragit® S100 as the agent regulating drug release. The dissolution profile of coated pellets showed good control of drug release from the polymer at the two levels of coating evaluated (8% and 10%, but only the 10% coated pellets were statistically similar to Asalit® 400 mg.A mesalazina (5-ASA tem se apresentado como fármaco padrão para o tratamento da doença inflamatória intestinal (DII devido ao seu efeito local na mucosa intestinal e colônica. A terapia efetiva e segura desta doença requer a chegada da substância ativa ao seu local de ação com maior eficiência. Nessa busca, tem se destacado o uso de Sistemas Multiparticulados, forma farmacêutica de liberação modificada, em que o fármaco está dividido em várias subunidades funcionais de liberação, sob a forma de grânulos ou péletes, que quando administrados, são rapidamente desintegrados distribuindo seu conteúdo por todo trato

  4. A comparative approach to synthesis and sintering of alumina/yttria nanocomposite powders using different precipitants

    Energy Technology Data Exchange (ETDEWEB)

    Kafili, G. [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of); Movahedi, B., E-mail: b.movahedi@ast.ui.ac.ir [Department of Nanotechnology Engineering, Faculty of Advanced Sciences and Technologies, University of Isfahan, Isfahan, 81746-73441 (Iran, Islamic Republic of); Milani, M. [Faculty of Advanced Materials and Renewable Energy Research Center, Tehran (Iran, Islamic Republic of)

    2016-11-01

    Alumina/yttria nanocomposite powder as an yttrium aluminum garnet (YAG) precursor was synthesized via partial wet route using urea and ammonium hydrogen carbonate (AHC) as precipitants, respectively. The products were characterized using X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and energy dispersive spectroscopy. The use of urea produced very tiny spherical Y-compounds with chemical composition of Y{sub 2}(CO{sub 3}){sub 3}·nH{sub 2}O, which were attracted to the surface of alumina nanoparticles and consequently, a core-shell structure was obtained. The use of ammonium hydrogen carbonate produced sheets of Y-compounds with chemical composition of Y(OH)CO{sub 3} covering the alumina nanoparticles. A fine-grained YAG ceramic (about 500 nm), presenting a non-negligible transparency (45% RIT at IR range) was obtained by the spark plasma sintering (SPS) of alumina-yttria nanocomposite synthesized in the urea system. This amount of transmission was obtained by only the sintering of the powder specimen without any colloidal forming process before sintering or adding any sintering aids or dopant elements. However, by spark plasma sintering of alumina-yttria nanocomposite powder synthesized in AHC system, an opaque YAG ceramic with an average grain size of 1.2 μm was obtained. - Highlights: • Urea proved to be an appropriate precipitant for obtaining a core-shell alumina/yttria nanocomposite. • Alumina/yttria nanocomposite powders with more appropriate morphology and highly sinterability. • A fine-grained YAG ceramic was obtained by SPS of alumina-yttria nanocomposite.

  5. Morphology and phase identification of micron to nanosized manganese oxide (MnO) with variations in sintering time

    Science.gov (United States)

    Sasongko, Muhammad Ilman Nur; Puspitasari, Poppy; Yazirin, Cepi; Tsamroh, Dewi Izzatus; Risdanareni, Puput

    2017-09-01

    Manganese oxide (MnO) occurs in many rock types and may take the form of minerals. MnO has its drawbacks, namely highly reactive oxidizing species classified as dangerous and explosive at temperatures above 55 °C. Despite this,MnO has excellent magnetic, electrochemical, and conductivity properties, which should be reduced to nano-size to maximize their use and improve the properties of MnO. Phase and morphology characterization of powder this research aims to reduce the grain size of the MnO from micro to nano using the sol-gel method with various sintering times. Sol-gel is a simple synthesis method that has been proven capable of synthesizing a wide variety of micro-sized oxide materials into nano. Sintering time is a technique performed in the synthesis process to dry the material to a temperature above the normal temperature. The temperature used for sintering starting from 600 °C to 1000 °C. Characterizations were done using XRD, SEM, EDX, and FTIR machines. The sintering processes in this study used a temperature of 600 °C with different sintering periods of 30, 60 and 90 minutes. The XRD characterization with a 30-minute sintering time resulted in the smallest MnO in the form crystalline powder of 47.3 nm. The highest intensity (degree of crystallinity) found in MnO sintered for 90 minutes. The results of the morphological characterization of SEM showed a morphological change in MnO from micro-sized triangular to nano-sized spherical shape. The EDX characterization results indicated that the 30-minute sintering caused the lowest change in Mn and the highest change in O. The results of FTIR characterization showed a shift in C-H and Mn-O followed by an increase in the group of N-H, C=O and Mn-O.

  6. Microbiological survey of birds of prey pellets.

    Science.gov (United States)

    Dipineto, Ludovico; Bossa, Luigi Maria De Luca; Pace, Antonino; Russo, Tamara Pasqualina; Gargiulo, Antonio; Ciccarelli, Francesca; Raia, Pasquale; Caputo, Vincenzo; Fioretti, Alessandro

    2015-08-01

    A microbiological survey of 73 pellets collected from different birds of prey species housed at the Wildlife Rescue and Rehabilitation Center of Napoli (southern Italy) was performed. Pellets were analyzed by culture and biochemical methods as well as by serotyping and polymerase chain reaction. We isolated a wide range of bacteria some of them also pathogens for humans (i.e. Salmonella enterica serotype Typhimurium, Campylobacter coli, Escherichia coli O serogroups). This study highlights the potential role of birds of prey as asymptomatic carriers of pathogenic bacteria which could be disseminated in the environment not only through the birds of prey feces but also through their pellets. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Development of pellet injection systems for ITER

    International Nuclear Information System (INIS)

    Combs, S.K.; Gouge, M.J.; Baylor, L.R.

    1995-01-01

    Oak Ridge National Laboratory (ORNL) has been developing innovative pellet injection systems for plasma fueling experiments on magnetic fusion confinement devices for about 20 years. Recently, the ORNL development has focused on meeting the complex fueling needs of the International Thermonuclear Experimental Reactor (ITER). In this paper, we describe the ongoing research and development activities that will lead to a ITER prototype pellet injector test stand. The present effort addresses three main areas: (1) an improved pellet feed and delivery system for centrifuge injectors, (2) a long-pulse (up to steady-state) hydrogen extruder system, and (3) tritium extruder technology. The final prototype system must be fully tritium compatible and will be used to demonstrate the operating parameters and the reliability required for the ITER fueling application

  8. Feasibility studies of concomitant administration of optimized formulation of probiotic-loaded Vancomycin hydrochloride pellets for colon delivery.

    Science.gov (United States)

    Avachat, Amelia M; Shinde, Amol S

    2016-01-01

    Objective of this study was to develop Vancomycin HCl pellets loaded with Saccharomyces boulardii (S.b.) for pH-dependent system and CODES™ for augmenting the efficacy of Vancomycin HCl in the treatment of colitis. Pellets were prepared by extrusion-spheronization. In the pH-dependent system, the pellets were coated with Eudragit FS 30D. These pellets exhibited spherical form and a uniform surface coating. The CODES™ system consisted of three components: core containing mannitol, drug and probiotic, an inner acid-soluble coating layer, and an outer layer of enteric coating material. Statistical factorial design was used to optimize both formulations. Scanning electron micrographs of coated pellets revealed uniform coating. In vitro drug release of these coated pellets was studied sequentially in various buffers with (2%) and without rat cecal content for a period of 12 h. From the optimized pH-dependent formulation, F6 (20% w/w coating level and 15% w/v concentration of polymer), higher amount of probiotic was released in earlier time phase (first 5 h) as compared to the CODES™ and so R5 [containing acid-soluble inner coating layer (15% w/w coating level and 12% w/v concentration of Eudragit E100), and an outer layer of enteric coating material (12% w/w coating level and 10% w/v concentration of Eudragit L100)] was considered as the best formulation after confirming in vivo X-ray studies conducted on rabbits, suggesting that Vancomycin HCl and S.b. may be co-administered as pellets [CODES™] to enhance the effectiveness of Vancomycin HCl in the treatment of colitis without its associated side effects, which can only be confirmed after clinical trials.

  9. Fuel pellets from lodge pole pine first thinnings

    Energy Technology Data Exchange (ETDEWEB)

    Hoegqvist, Olof; Larsson, Sylvia H.; Samuelsson, Robert; Lestander, Torbjoern A. [Swedish Univ. of Agricultural Sciences, Unit of Biomass Technology and Chemistry, Umeaa (Sweden)], e-mail: sylvia.larsson@slu.se

    2012-11-01

    Stemwood and whole trees of lodgepole pine (Pinus contorta Dougl. var. latifolia L.) were evaluated as raw materials for fuel pellets in a pilot scale pelletizing study. Pellet and pelletizing properties were measured and modeled in an experimental design where raw material moisture content (%), die channel length (mm), and storage time (days) were varied. Additionally, ash contents (%), extractive contents (%), and ash melting temperatures (deg C) were analyzed. For both assortments, raw material moisture content was positively correlated to pellet bulk density and durability (range 9-13%, wet base). Both assortments had ash contents below 0.7%, and thus, fulfilled the demands for class A1 pellets.

  10. Fuel Pellets Production from Biodiesel Waste

    Directory of Open Access Journals (Sweden)

    Kawalin Chaiyaomporn

    2010-01-01

    Full Text Available This research palm fiber and palm shell were used as raw materials to produce pelletised fuel, and waste glycerol were used as adhesive to reduce biodiesel production waste. The aim of this research is to find optimum ratio of raw material (ratio of palm fiber and palm shell, raw material size distribution, adhesive temperature, and ratio of ingredients (ratio of raw material, waste glycerol, and water. The optimum ratio of pelletized fuel made only by palm fiber was 50:10:40; palm fiber, water, and waste glycerol respectively. In the best practice condition; particle size was smaller than 2 mm, adhesive glycerol was heated. From the explained optimum ratio and ingredient, pelletizing ratio was 62.6%, specific density was 982.2 kg/m3, heating value was 22.5 MJ/kg, moisture content was 5.9194%, volatile matter was 88.2573%, fix carbon content was 1.5894%, and ash content was 4.2339% which was higher than the standard. Mixing palm shell into palm fiber raw material reduced ash content of the pellets. The optimum raw material ratio, which minimizes ash content, was 80 to 20 palm fiber and palm shell respectively. Adding palm shell reduced ash content to be 2.5247% which was higher than pelletized fuel standard but followed cubed fuel standard. At this raw material ratio, pelletizing ratio was 70.5%, specific density was 774.8 kg/m3, heating value was 19.71 MJ/kg, moisture content was 9.8137%, volatile matter was 86.2259%, fix carbon content was 1.4356%, and compressive force was 4.83 N. Pelletized fuel cost at optimum condition was 1.14 baht/kg.

  11. Pellet culture model for human primary osteoblasts.

    Science.gov (United States)

    Jähn, K; Richards, R G; Archer, C W; Stoddart, M J

    2010-09-06

    In vitro monolayer culture of human primary osteoblasts (hOBs) often shows unsatisfactory results for extracellular matrix deposition, maturation and calcification. Nevertheless, monolayer culture is still the method of choice for in vitro differentiation of primary osteoblasts. We believe that the delay in mature ECM production by the monolayer cultured osteoblasts is determined by their state of cell maturation. A functional relationship between the inhibition of osteoblast proliferation and the induction of genes associated with matrix maturation was suggested within a monolayer culture model for rat calvarial osteoblasts. We hypothesize, that a pellet culture model could be utilized to decrease initial proliferation and increase the transformation of osteoblasts into a more mature phenotype. We performed pellet cultures using hOBs and compared their differentiation potential to 2D monolayer cultures. Using the pellet culture model, we were able to generate a population of cuboidal shaped central osteoblastic cells. Increased proliferation, as seen during low-density monolayer culture, was absent in pellet cultures and monolayers seeded at 40,000 cells/cm2. Moreover, the expression pattern of phenotypic markers Runx2, osterix, osteocalcin, col I and E11 mRNA was significantly different depending on whether the cells were cultured in low density monolayer, high density monolayer or pellet culture. We conclude that the transformation of the osteoblast phenotype in vitro to a more mature stage can be achieved more rapidly in 3D culture. Moreover, that dense monolayer leads to the formation of more mature osteoblasts than low-density seeded monolayer, while hOB cells in pellets seem to have transformed even further along the osteoblast phenotype.

  12. Pellet culture model for human primary osteoblasts

    Directory of Open Access Journals (Sweden)

    K Jähn

    2010-09-01

    Full Text Available In vitro monolayer culture of human primary osteoblasts (hOBs often shows unsatisfactory results for extracellular matrix deposition, maturation and calcification. Nevertheless, monolayer culture is still the method of choice for in vitro differentiation of primary osteoblasts. We believe that the delay in mature ECM production by the monolayer cultured osteoblasts is determined by their state of cell maturation. A functional relationship between the inhibition of osteoblast proliferation and the induction of genes associated with matrix maturation was suggested within a monolayer culture model for rat calvarial osteoblasts. We hypothesize, that a pellet culture model could be utilized to decrease initial proliferation and increase the transformation of osteoblasts into a more mature phenotype. We performed pellet cultures using hOBs and compared their differentiation potential to 2D monolayer cultures. Using the pellet culture model, we were able to generate a population of cuboidal shaped central osteoblastic cells. Increased proliferation, as seen during low-density monolayer culture, was absent in pellet cultures and monolayers seeded at 40,000 cells/cm2. Moreover, the expression pattern of phenotypic markers Runx2, osterix, osteocalcin, col I and E11 mRNA was significantly different depending on whether the cells were cultured in low density monolayer, high density monolayer or pellet culture. We conclude that the transformation of the osteoblast phenotype in vitro to a more mature stage can be achieved more rapidly in 3D culture. Moreover, that dense monolayer leads to the formation of more mature osteoblasts than low-density seeded monolayer, while hOB cells in pellets seem to have transformed even further along the osteoblast phenotype.

  13. The influence of raw material characteristics on the industrial pelletizing process and pellet quality

    Energy Technology Data Exchange (ETDEWEB)

    Arshadi, Mehrdad; Geladi, Paul; Lestander, Torbjoern [Unit of Biomass Technology and Chemistry, Swedish University of Agricultural Sciences (Sweden); Gref, Rolf [Department of Silviculture, Division of Forest Technology, Swedish University of Agricultural Sciences (Sweden); Dahlqvist, Sten-Axel [SAT AS, P.O. Box 286, N-0216 Oslo (Norway)

    2008-12-15

    Industrial pelletizing of sawdust was carried out as a designed experiment in the factors: sawdust moisture content, fractions of fresh pine, stored pine and spruce. The process parameters and response variables were energy consumption, pellet flow rate, pellet bulk density, durability and moisture content. The final data consisted of twelve industrial scale runs. Because of the many response variables, data evaluation was by principal component analysis of a 12 x 9 data matrix. The two principal component model showed a clustering of samples, with a good reproducibility of the center points. It also showed a positive correlation of energy consumption, bulk density and durability all negatively correlated to flow rate and moisture content. The stored pine was more related to high durability and bulk density. The role of the spruce fraction was unclear. The design matrix, augmented with the process parameters was a 12 x 6 matrix. Partial least squares regression showed excellent results for pellet moisture content and bulk density. The model for durability was promising. A 12 x 21 data matrix of fatty- and resin acid concentrations measured by GC-MS showed the differences between fresh and stored pine very clearly. The influence of the spruce fraction was less clear. However, the influence of the fatty- and resin acids on the pelletizing process could not be confirmed, indicating that other differences between fresh and stored pine sawdust have to be investigated. This work shows that it is possible to design the pelletizing process for moderate energy consumption and high pellet quality. (author)

  14. Effects of physical properties of PEG 6000 on pellets produced by melt pelletization.

    Science.gov (United States)

    Wong, T W; Wan, L S; Heng, P W

    1999-08-01

    This study examined the effects of polyethylene glycol (PEG) binders of different physical forms and from different commercial sources on size and size distribution of pellets produced. The meltable binders used were PEG 6000 in the form of flakes, and coarse and fine powders, and melt pelletization using lactose 450 M was carried out in an 8-liter high-shear mixer. Binder particle size, molecular weight, tack, and viscosity were determined. The results showed that the size and size distribution of the pellets obtained could not be explained by the binder particle size. The size and size distribution of the pellets were related to the tack and viscosity of the molten binders. PEGs used were labeled as the same nominal molecular weight grade, although their determined molecular weights could be quite different. Differences in tack and viscosity of the molten binders were associated with determined molecular weight of the binders. The melt pelletization process is sensitive to tack and viscosity of the molten binders. When different PEG brands of the same nominal molecular weight or different batches of the same brand are used in melt pelletization, it is important to characterize the tack and viscosity of the binders used. The effects of the physical form of binders on the pellet quality appear to be less important when compared to the influences of tack and viscosity of the molten binder.

  15. Effect of off-bottom clearance on properties of pellets produced by melt pelletization.

    Science.gov (United States)

    Heng, P W; Wan, L S; Wong, T W

    1999-01-01

    This study examines the influence of off-bottom clearance on size and size distribution of pellets produced during melt pelletization at different postmelt impeller speeds and binder concentrations using lactose and polyethylene glycol. Melt pelletization of lactose powder 450 M in an 8-liter highshear mixer, the floor of which was made of polytetrafluoroethylene (PTFE), was carried out with polyethylene glycol 3000 as the meltable binder. Erosion of the PTFE floor of the mixer occurred with time of use and this caused a change in the off-bottom clearance. The findings showed that with a wider clearance, the size distribution of pellets was wider and pellets were much larger. These changes were the results of changes in the mixing intensity and impact frequency of the mass in relation to the eddies formed within the off-bottom clearance. The changes were not associated with the reduction in the circulating material load by entrapment into the off-bottom clearance. In the melt pelletization process, the quality of product was higher if the clearance was kept to a minimum. The off-bottom clearance was best measured at the beginning of each pelletization run because the PTFE floor of the mixer was prone to erosion.

  16. Development and optimization of solid dispersion containing pellets of itraconazole prepared by high shear pelletization.

    Science.gov (United States)

    Ye, Guanhao; Wang, Siling; Heng, Paul Wan Sia; Chen, Ling; Wang, Chao

    2007-06-07

    This study investigated the solid dispersion containing pellets of itraconazole for enhanced drug dissolution rate. The influence of process parameters used during high shear pelletization on the pellet properties including pellet size and dissolution rate was also studied. Solid dispersions of itraconazole were prepared with Eudragit E100, a hydrophilic polymer, by a simple fusion method followed by powdered and characterized by differential scanning calorimetry and X-ray powder diffraction. Solid dispersions containing pellets were consequently prepared using a lab-scale high shear mixer. In order to improve the product quality, a central composite design was applied to optimize the critical process variables, such as impeller speed and kneading time, and the results were modeled statistically. Itraconazole was presented as an amorphous state in the solid dispersion prepared at a drug to polymer ratio of 1:2. Both studied parameters had great effect on the responses. Powdered solid dispersion and pellets prepared using the optimal parameter settings showed approximately 30- and 70-fold increases in dissolution rate over the pure drug, respectively. Solid dispersion prepared by simple fusion method could be an option for itraconazole solubility enhancement. Pelletization process in high shear mixer can be optimized effectively by central composite design.

  17. International Trade of Wood Pellets (Brochure)

    Energy Technology Data Exchange (ETDEWEB)

    2013-05-01

    The production of wood pellets has increased dramatically in recent years due in large part to aggressive emissions policy in the European Union; the main markets that currently supply the European market are North America and Russia. However, current market circumstances and trade dynamics could change depending on the development of emerging markets, foreign exchange rates, and the evolution of carbon policies. This fact sheet outlines the existing and potential participants in the wood pellets market, along with historical data on production, trade, and prices.

  18. Development of pellet chain for charge carrying

    International Nuclear Information System (INIS)

    Chung, K.H.; Ko, S.K.; Choi, B.H.; Hong, J.H.

    1988-01-01

    This paper reports on the development of pellet chain and charge induction components which are used for charge carrying in electrostatic accelerators. It has very simple structure, and its fabrication cost is low. As the results of the test, first, mechanical vibration is reduced for operation and torsional stress due to belt twisting is removed completely. Second, after insertion of the material with high dielectric constant in charge induction assembly, the capacitance between pellets and inductor is increased. Third, for measurement of the life time of chain, it is continuously on the operation

  19. CO{sub 2} pellet blasting studies

    Energy Technology Data Exchange (ETDEWEB)

    Archibald, K.E.

    1997-01-01

    Initial tests with CO{sub 2} pellet blasting as a decontamination technique were completed in 1993 at the Idaho Chemical Processing Plant (ICPP) at the Idaho National Engineering Laboratory (INEL). During 1996, a number of additional CO{sub 2} pellet blasting studies with Alpheus Cleaning Technologies, Oak Ridge National Laboratory, and Pennsylvania State University were conducted. After the testing with Alpheus was complete, an SDI-5 shaved CO{sub 2} blasting unit was purchased by the ICPP to test and determine its capabilities before using in ICPP decontamination efforts. Results of the 1996 testing will be presented in this report.

  20. Titanium Powder Sintering in a Graphite Furnace and Mechanical Properties of Sintered Parts

    Directory of Open Access Journals (Sweden)

    Changzhou Yu

    2017-02-01

    Full Text Available Recent accreditation of titanium powder products for commercial aircraft applications marks a milestone in titanium powder metallurgy. Currently, powder metallurgical titanium production primarily relies on vacuum sintering. This work reported on the feasibility of powder sintering in a non-vacuum furnace and the tensile properties of the as-sintered Ti. Specifically, we investigated atmospheric sintering of commercially pure (C.P. titanium in a graphite furnace backfilled with argon and studied the effects of common contaminants (C, O, N on sintering densification of titanium. It is found that on the surface of the as-sintered titanium, a severely contaminated porous scale was formed and identified as titanium oxycarbonitride. Despite the porous surface, the sintered density in the sample interiors increased with increasing sintering temperature and holding time. Tensile specimens cut from different positions within a large sintered cylinder reveal different tensile properties, strongly dependent on the impurity level mainly carbon and oxygen. Depending on where the specimen is taken from the sintered compact, ultimate tensile strength varied from 300 to 580 MPa. An average tensile elongation of 5% to 7% was observed. Largely depending on the interstitial contents, the fracture modes from typical brittle intergranular fracture to typical ductile fracture.

  1. Laser sintering of magnesia with nanoparticles of iron oxide and aluminum oxide

    Energy Technology Data Exchange (ETDEWEB)

    García, L.V.; Mendivil, M.I.; Roy, T.K. Das; Castillo, G.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66451 (Mexico); CIIDIT, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2015-05-01

    Highlights: • Laser sintered MgO pellets with nanoparticles of Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}. • Characterized these pellets by XRD, SEM and XPS. • Spinel formations were observed in both cases. • Changes in morphology and structure were analyzed. - Abstract: Nanoparticles of iron oxide (Fe{sub 2}O{sub 3}, 20–40 nm) and aluminum oxide (Al{sub 2}O{sub 3}, 50 nm) were mixed in different concentrations (3, 5 and 7 wt%) in a magnesium oxide (MgO) matrix. The mixture pellet was irradiated with 532 nm output from a Q-switched Nd:YAG laser using different laser fluence and translation speed for sintering. The refractory samples obtained were analyzed using X-ray diffraction technique, scanning electron microscopy and X-ray photoelectron spectroscopy. The results showed that the samples irradiated at translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2} with a concentration of 5 and 7 wt% of Fe{sub 2}O{sub 3} presented the MgFe{sub 2}O{sub 4} spinel-type phase. With the addition of Al{sub 2}O{sub 3} nanoparticles, at a translation speed of 110 μm/s and energy fluence of 1.7 J/cm{sup 2}, there were the formations of MgAl{sub 2}O{sub 4} spinel phase. The changes in morphologies and microstructure due to laser irradiation were analyzed.

  2. Wood pellets in a power plant - mixed combustion of coal and wood pellets

    International Nuclear Information System (INIS)

    Nupponen, M.

    2001-01-01

    The author reviews in his presentation the development of Turku Energia, the organization of the company, the key figures of the company in 2000, as well as the purchase of energy in 2000. He also presents the purchase of basic heat load, the energy production plants of the company, the sales of heat in 2000, the emissions of the plants, and the fuel consumption of the plants in 2000. The operating experiences of the plants are also presented. The experiences gained in Turku Energia on mixed combustion of coal and wood pellets show that the mixing ratios, used at the plants, have no effect on the burning properties of the boiler, and the use of wood pellets with coal reduce the SO 2 and NO x emissions slightly. Simultaneously the CO 2 share of the wood pellets is removed from the emissions calculations. Several positive effects were observed, including the disappearance of the coal smell of the bunker, positive publicity of the utilization of wood pellets, and the subsidies for utilization of indigenous fuels in power generation. The problems seen include the tendency of wood pellets to arc the silos, especially when the pellets include high quantities of dust, and the loading of the trucks and the pneumatic unloading of the trucks break the pellets. Additionally the wood pellets bounce on the conveyor so they drop easily from the conveyor, the screw conveyors designed for conveying grain are too weak and they get stuck easily, and static electricity is easily generated in the plastic pipe used as the discharge pipe for wood pellet (sparkling tendency). This disadvantage has been overcome by using metal net and grounding

  3. Development of the centrifugal pellet injector for JT-60U

    International Nuclear Information System (INIS)

    Kizu, Kaname; Hiratsuka, Hajime; Ichige, Hisashi

    2001-03-01

    For core fueling of JT-60U plasmas, a repetitive pellet injector which centrifugally accelerates D 2 cubic pellets using a straight rod has been developed. This centrifugal pellet injector can eject trains of up to 40 cubic pellets at frequencies of 1-10 Hz and velocities of 0.3-1.0 km/s. The average pellet mass is 3.6x10 20 atoms/pellet below 0.7 m/s. Key techniques for the development were a mesh structured acceleration component for removing gas sublimated from the pellet and a funnel with an appropriate angle connected just behind the acceleration chamber for introducing the pellet to plasma without destruction. Using the mesh structured components, the horizontal angular distribution of pellets ejected became narrow, because irregular pellet motion caused by sublimated gas was reduced. To investigate the performance of the injector, pellet injection experiments from the low magnetic field side (LFS) were conducted using ohmic heating plasmas. Central fueling and enhanced fueling rate have been observed. Dα intensity around the divertor region was reduced in a pellet injection plasma compared to gas puffing, indicating low recycling rate was maintained with the pellet injection. (author)

  4. Influence of starting material particle size on pellet surface roughness.

    Science.gov (United States)

    Sarkar, Srimanta; Ang, Bee Hwee; Liew, Celine Valeria

    2014-02-01

    The purpose of this study was to investigate the effect of pelletization aids, i.e., microcrystalline cellulose (MCC) and cross-linked polyvinyl pyrrolidone (XPVP), and filler, i.e., lactose, particle size on the surface roughness of pellets. Pellets were prepared from powder blends containing pelletization aid/lactose in 1:3 ratio by extrusion-spheronization. Surface roughness of pellets was assessed quantitatively and qualitatively using optical interferometry and scanning electron microscopy, respectively. Both quantitative and qualitative surface studies showed that surface roughness of pellets depended on the particle size of XPVP and lactose used in the formulation. Increase in XPVP or lactose particle size resulted in rougher pellets. Formulations containing MCC produced pellets with smoother surfaces than those containing XPVP. Furthermore, surface roughness of the resultant pellets did not appear to depend on MCC particle size. Starting material particle size was found to be a critical factor for determining the surface roughness of pellets produced by extrusion-spheronization. Smaller particles can pack well with lower peaks and valleys, resulting in pellets with smoother surfaces. Similar surface roughness of pellets containing different MCC grades could be due to the deaggregation of MCC particles into smaller subunits with more or less similar sizes during wet processing. Hence, for starting materials that deaggregate during the wet processing, pellet surface roughness is influenced by the particle size of the material upon deaggregation.

  5. Thermodynamics and mechanisms of sintering

    International Nuclear Information System (INIS)

    Pask, J.A.

    1978-10-01

    A phenomenological overview and exploration of the thermodynamic and geometric factors play a role in the process of densification of model compact systems consisting of crystalline spheres of uniform size in regular and irregular packing that form grain boundaries at every contact point. A further assumption is the presence of isotropic surface and grain boundary energies. Although such systems are unrealistic in comparison with normal powder compacts, their potential sintering behavior can be analyzed and provided with a limiting set of behavior conditions which can be looked upon as one boundary condition. This approach is logically realistic since it is easier to understand and provide a basis for understanding the more complex real powder systems

  6. Science of sintering and its future

    International Nuclear Information System (INIS)

    Ristic, M.M.

    1975-01-01

    Some new books published by M.Yu. Baljshin, V.A. Ivensen, V.V. Skorohod and others are characterized by the wish to give a complete approach to the problems of sintering theory. Bearing just this in mind while writing the book ''An Essay on the Generalization of Sintering Theory'' (G.V.Samsonov, M.M. Ristic with the collaborators) an idea was born: to ask the most eminent scientists in this field to present their own opinions on the theme ''The Science of Sintering and Modern Views on its Future''. There were formed 18 questions, given in the appendix to be answered. The received answers were presented in 10 chapters of this book. The fourth part of the book consists of papers of eminent scientists engaged in the field of sintering science (some of which were published here for the first time). This material is published in the book with the consent of the authors and these original contributions provide a more profound knowledge of sintering. The initial idea, that the book should have a monograph character and in which the answers would serve as some data on the latest notions of the science of sintering, was somewhat changed since the original opinions of individual scientists are given in the book and these, are sometimes very contradictory. This, in fact, gives the book a special charm because the unsolved problems in the science of sintering are most evidently stressed in this way

  7. Decay rate of reindeer pellet-groups

    Directory of Open Access Journals (Sweden)

    Anna Skarin

    2008-06-01

    Full Text Available Counting of animal faecal pellet groups to estimate habitat use and population densities is a well known method in wildlife research. Using pellet-group counts often require knowledge about the decay rate of the faeces. The decay rate of a faecal pellet group may be different depending on e.g. substrate, size of the pellet group and species. Pellet-group decay rates has been estimated for a number of wildlife species but never before for reindeer (Rangifer tarandus. During 2001 to 2005 a field experiment estimating the decay rate of reindeer pellet groups was performed in the Swedish mountains close to Ammarnäs. In total the decay rate of 382 pellet groups in three different habitat types (alpine heath, birch forest and spruce forest was estimated. The slowest decay rate was found in alpine heath and there the pellet groups persisted for at least four years. If decay was assumed to take place only during the bare ground season, the estimated exponential decay rate was -0.027 pellet groups/week in the same habitat. In the forest, the decay was faster and the pellet groups did not persist more than two years. Performing pellet group counts to estimate habitat use in dry habitats, such as alpine heath, I will recommend using the faecal standing crop method. Using this method makes it possible to catch the animals’ general habitat use over several years. Abstract in Swedish / Sammanfattning:Nedbrytningshastighet av renspillningInom viltforskningen har spillningsinventeringar använts under flera årtionden för att uppskatta habitatval och populationstäthet hos olika djurslag. För att kunna använda data från spillningsinventeringar krävs ofta att man vet hur lång tid det tar för spillningen att brytas ner. Nedbrytningshastigheten är olika beroende på marktyp och djurslag. Nedbrytningshastighet på spillning har studerats för bland annat olika typer av hjortdjur, men det har inte studerats på ren (Rangifer tarandus tidigare. I omr

  8. JUST: Joint Upgraded Spherical Tokamak

    International Nuclear Information System (INIS)

    Azizov, E.A.; Dvorkin, N.Ya.; Filatov, O.G.

    1997-01-01

    The main goals, ideas and the programme of JUST, spherical tokamak (ST) for the plasma burn investigation, are presented. The place and prospects of JUST in thermonuclear investigations are discussed. (author)

  9. Spherical Primary Optical Telescope Testbed

    Data.gov (United States)

    National Aeronautics and Space Administration — This IRAD proposes to continue operation of the Spherical Primary Optical Telescope (SPOT) testbed as an image-based wavefront sensing demonstrator. In addition to...

  10. Glass reactive sintering as an alternative route for the synthesis of NZP glass-ceramics

    International Nuclear Information System (INIS)

    Chenu, Sebastien; Lebullenger, Ronan; Benard-Rocherulle, Patricia; Calvez, Guillaume; Guillou, Olivier; Rocherulle, Jean; Kidari, Abdessamad; Pomeroy, Mickael J.; Hampshire, Stuart

    2012-01-01

    The NZP-type crystal structure allows a large number of ionic substitutions which leads to ceramics with adjustable thermal expansion properties or interesting ionic conductivity. However, NZP is difficult to fabricate into monoliths because it requires both high temperatures and long sintering times. An alternative low temperature route to obtain a tungsten (IV) and tin (IV) containing NZP crystalline phase uses a process of glass reactive sintering of a phosphate glass. Using a microwave oven, a glass with the appropriate composition in the NaPO 3 -Sn(II)O-W(VI)O 3 ternary diagram is prepared by a conventional melting and casting technique. After crushing, the glass powder is pressed at room temperature. The green pellet is cured during various times at temperatures where glass reactive sintering takes place. From XRD and DTA experiments, we have shown that different parameters influence the achievement of NZP phase. Consequently, specific conditions, such as (i) initial glass composition, (ii) equimolar quantities of SnO and WO 3 , (iii) glass particle size lower than 100 μ m, and (iv) curing conducted under air, are required to obtain a glass-ceramic with a single crystalline phase with the NZP-type crystal structure. (authors)

  11. Fabrication and properties of YBa2Cu3O7- x ceramics at different sintering temperatures

    Science.gov (United States)

    Prayoonphokkharat, Poom; Jiansirisomboon, Sukanda; Watcharapasorn, Anucha

    2013-07-01

    The influence of sintering temperatures on the fabrication of YBCO ceramics under normal air atmosphere was investigated in this study. YBCO ceramics were prepared by mixing starting compounds of Y2O3, BaCO3 and CuO powders, which were calcined at 850°C for 12 h. The powder was pelletized and sintered at different temperatures, from 930°C-1050°C, for 12 h. Phase identification was carried out by x-ray diffraction (XRD) technique. Scanning electron microscopy (SEM) with energy dispersive x-ray analysis (EDS) was used to study microstructure and chemical composition. In addition, density, Vickers hardness properties, the change of resistance and dielectric properties with temperature above T c were investigated. It was found that, at 950°C-1000°C, high-purity YBCO ceramic could be obtained. Outside this temperature range, either impurity phases were present or melting occurred. SEM images showed that grain size, which ranged from 1.5-2.5 µm, and hardness were related to density and liquid phase present in the sample. Furthermore, the sintering temperature affected oxygen content which, in turn, determined the conductive or semi-conductive behavior observed by electrical property measurement.

  12. Spherical tokamak development in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma; Barbosa, L.F.W. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo; Patire Junior, H. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Mecanica Espacial e Controle; The high-power microwave sources group

    2003-12-01

    This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  13. Spherical tokamak development in Brazil

    International Nuclear Information System (INIS)

    Ludwig, G.O.; Del Bosco, E.; Ferreira, J.G.; Berni, L.A.; Oliveira, R.M.; Andrade, M.C.R.; Shibata, C.S.; Ueda, M.; Barroso, J.J.; Castro, P.J.; Barbosa, L.F.W.; Patire Junior, H.; The high-power microwave sources group

    2003-01-01

    This paper describes the general characteristics of spherical tokamaks, or spherical tori, with a brief overview of work in this area already performed or in progress at several institutions worldwide. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esferico) project, its research program, technical characteristics and operating conditions as of December, 2002 at the Associated Plasma Laboratory (LAP) of the National Space Research Institute (INPE) in Brazil. (author)

  14. Sintering and Microstructures of SUS 316L Powder Produced by 3D Printing Process

    Directory of Open Access Journals (Sweden)

    Kim W.J.

    2017-06-01

    Full Text Available Selective laser sintering (SLS is a type of laminating sintering technique, using CO2 laser with (metal, polymer, and ceramic powders. In this result, the flake SUS 316L was used to achieve a high porous product, and compare to spherical type. After SLS, the porosity of flake-type sample with 34% was quite higher than that of the spherical-type one that had only 11%. The surface roughness of the flake SLS sample were also investigated in both inner and surface parts. The results show that the deviation of the roughness of the surface part is about 64.40μm, while that of the internal one was about 117.65μm, which presents the containing of high porosity in the uneven surfaces. With the process using spherical powder, the sample was quite dense, however, some initial particles still remained as a result of less energy received at the beneath of the processing layer.

  15. Immobilization of Uranium Silicides in Sintered Glass

    International Nuclear Information System (INIS)

    Mateos, P.; Russo, D.O.; Heredia, A.D.; Sanfilippo, M.

    2003-01-01

    High activity nuclear spent fuels vitrification by fusion is a well known technology which has industrial scale in France, England, Japan, EEUU. Borosilicates glasses are used in this process.Sintered glasses are an alternative to the immobilization task in which there is also a wide experience around the world.The available technics are: cold pressing and sintering , hot-pressing and hot isostatic pressing.This work compares Borosilicates and Iron silicates sintered glasses behaviour when different ammounts of nuclear simulated waste is added

  16. Solidification of HLLW into sintered ceramics

    International Nuclear Information System (INIS)

    O-Oka, K.; Ohta, T.; Masuda, S.; Tsunoda, N.

    1979-01-01

    Simulated HLLW from the PNC reprocessing plant at Tokai was solidified into sintered ceramics by normal sintering or hot-pressing with addition of some oxides. Among various ceramic products obtained so far, the most preferable was nepheline-type sintered solids formed with addition of SiO 2 and Al 2 O 3 to the simulated waste calcine. The solid shows advantageous properties in leach rate and mechanical strength, which suggest that the ceramic solids were prepared with additions of ZrO 2 or MnO 2 , and some of them showed good characteristics

  17. Effect of sintering temperature and heating mode on consolidation of ...

    Indian Academy of Sciences (India)

    Microwave sintering was performed in 2.45 GHz multimode microwave furnace at temperatures ranging from 570–630 °C. Microwave sintering at a heating rate of as high as 22°C/min resulted in ∼55% reduction of processing time as compared to conventional sintering. A lower sintered density observed in the case of ...

  18. Sintering of nano crystalline o silicon carbide doping with

    Indian Academy of Sciences (India)

    Sinterable silicon carbide powders were prepared by attrition milling and chemical processing of an acheson type -SiC. Pressureless sintering of these powders was achieved by addition of aluminium nitride together with carbon. Nearly 99% sintered density was obtained. The mechanism of sintering was studied by ...

  19. Plastic pellets on the Caranzalem beach sands, Goa, India

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    Postmonsoonal survey of Caranzalem beach, Goa, India indicated the presence of plastic pellets. These pellets varied in shape, size and number, and are considered to be contaminants of marine environment...

  20. Pellet injection with improved confinement in ASDEX

    International Nuclear Information System (INIS)

    Kaufmann, M.; Buechl, K.; Fussmann, G.; Gehre, O.; Grassie, K.; Gruber, O.; Haas, G.; Janeschitz, G.; Kornherr, M.; Lackner, K.; Lang, R.S.; Mast, K.F.; McCormick, K.; Mertens, V.; Neuhauser, J.; Niedermeyer, H.; Sandmann, W.; Zasche, D.; Zehrfeld, H.P.; Pietrzyk, Z.A.

    1987-07-01

    Tokamak discharges with repetitive pellet fueling were investigated in the ASDEX divertor device. The importance of sufficiently high divertor recycling for successful density build-up in the bulk plasma was demonstrated. In OH-heated discharges with high recycling an energy confinement time of 160 ms was reached, the normal values being 80 ms in the roll-over region. The peaked density profiles in this cases were accompanied by reduced or suppressed sawtooth activity and finally ended in a phase of strong central impurity accumulation. The particle transport was characterized by strong, non-classical inward drift, while the improved energy transport can be explained by two alternatives: (1) a local model which assumes neo-Alcator χ e for the electrons and an χ i = 3χ neocl for the ions in the gas puff cases reduced to χ i = χ neocl for the optimum pellet cases; (2) a profile consistency picture were T e (a) determines the energy confinement. Low-power, NI-heated discharges with pellet fueling behave like ohmic discharges, while for high power in the L-mode no successful density build-up was possible, and τ E was not improved. The H-regime was extended to anti n e = 1.2x10 20 m -3 by the injection of pellets. In this case a density build-up takes place, but a further density profile peaking could not be observed. (orig.)

  1. The Manufacturing Process of Bamboo Pellets

    Science.gov (United States)

    Zhijia Liu; Zehui Jiang; Zhiyong Cai; Benhua Fei; Xing' e Liu

    2012-01-01

    Bamboo was a kind of biomass materials and had great potential as a bio-energy resource of the future in China. The physical and combustion properties of bamboo pellets were determined and the effects of moisture content (MC) and sizes of particle on these properties were investigated in this research. The results showed that MC and sizes of particle affected these...

  2. Thermochemical reduction of pelletized gypsum mixed with ...

    African Journals Online (AJOL)

    2015-04-03

    Apr 3, 2015 ... problems and improve waste gypsum conversion yields, pelletization of waste gypsum in the presence of binders (starch and cellulose) ... construction of a 20 Mℓ/d emergency neutralization plant for. AMD treatment as one ... powders derived from agricultural residues such as maize cobs are comparable to ...

  3. Torrefaction of wood pellets: New solutions

    Science.gov (United States)

    Zaichenko, V. M.; Shterenberg, V. Ya.

    2017-10-01

    The current state of the market of conventional and torrefied wood pellets and the trends of its development have been analyzed. The advantages and disadvantages of pellets of both types have been compared with other alternative fuels. The consumer segment in which wood pellets are the most competitive has been determined. The original torrefaction technology using exhaust gas heat from a standard gas engine that was developed at the Joint Institute for High Technologies and the scheme of an experimental unit for the elaboration of the technology have been presented. The scheme of the combined operation of a torrefaction unit and a standard hot water boiler, which makes it possible to utilize the heat of exhaust steam-and-gas products of torrefaction with the simultaneous prevention of emissions of harmful substances into the environment, has been proposed. The required correlation between the capacity of the torrefaction unit and the heating boiler house has been estimated for optimal operation under the conditions of the isolated urban village in a region that is distant from the areas of extraction of traditional fuels and, at the same time, has quite sufficient resources of raw materials for the production of wood pellets.

  4. Co-gasification of pelletized wood residues

    Energy Technology Data Exchange (ETDEWEB)

    Carlos A. Alzate; Farid Chejne; Carlos F. Valdes; Arturo Berrio; Javier De La Cruz; Carlos A. Londono [Universidad Nacional de Colombia, Antioquia (Colombia). Grupo de Termodinamica Aplicada y Energias Alternativas

    2009-03-15

    A pelletization process was designed which produces cylindrical pellets 8 mm in length and 4 mm in diameter. These ones were manufactured using a blend of Pinus Patula and Cypress sawdust and coal in proportions of 0%, 5%, 10%, 20%, and 30% v/v of coal of rank sub-bituminous extracted from the Nech mine (Amaga-Antioquia). For this procedure, sodium carboxymethyl cellulose (CMC) was used as binder at three different concentrations. The co-gasification experiments were carried out with two kinds of mixtures, the first one was composed of granular coal and pellets of 100% wood and the second one was composed of pulverized wood and granular coal pellets. All samples were co-gasified with steam by using an electrical heated fluidized-bed reactor, operating in batches, at 850{sup o}C. The main components of the gaseous product were H{sub 2}, CO, CO{sub 2}, CH{sub 4}, and N{sub 2} with approximate quantities of 59%, 6.0%, 20%, 5.0%, and 9.0% v/v, respectively, and the higher heating values ranged from between 7.1 and 9.5 MJ/Nm{sup 3}.

  5. DEVELOPMENT OF A CASSAVA PELLETING MACHINE

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... can be formed in dough-like fashion manner, includ- ing cassava. Cassava pellet is an unfermented dried cassava product obtained by compressing raw cassava chips under appropriate processing conditions result- ing in the formation of dried bulky product suitable for the animal feed industry with an ...

  6. Thermoelectric properties of n-type 95%Bi2Te3–5%Bi2Se3 compounds fabricated by gas-atomization and spark plasma sintering

    International Nuclear Information System (INIS)

    Kim, Hyo-Seob; Hong, Soon-Jik

    2014-01-01

    Highlights: • Gas Atomization process was used to fabricate 95%Bi 2 Te 3 –5%Bi 2 Se 3 powders. • Characterization of gas atomized powders were conducted. • SPS process was used to sinter the atomized powders at different sintering temp. • Thermoelectric properties, density and hardness of SPS-ed bulks were analyzed. -- Abstract: In this study, n-type 95%Bi 2 Te 3 –5%Bi 2 Se 3 doped with 0.04% SbI 3 thermoelectric materials was fabricated by gas-atomization and spark plasma sintering (SPS) at a temperature range of 623–723 K. The microstructure of the gas atomized powder shows spherical shape, fine particle size and homogeneously distributed grains. The density of the sintered bulk reached nearly 100% of the theoretical density, where micro Vickers Hardness was found around 54–57 Hv. The Seebeck coefficient (α) of the sintered bulk decreased while electrical resistivity and thermal conductivity (κ) increased with increasing sintering temperature to 723 K, resulting in a decrease in figure of merit. The maximum figure of merit (ZT) was 0.76, which was obtained in the sintered bulk at 623 K

  7. Lipids bearing extruded-spheronized pellets for extended release of poorly soluble antiemetic agent-Meclizine HCl.

    Science.gov (United States)

    Qazi, Faaiza; Shoaib, Muhammad Harris; Yousuf, Rabia Ismail; Nasiri, Muhammad Iqbal; Ahmed, Kamran; Ahmad, Mansoor

    2017-04-12

    Antiemetic agent Meclizine HCl, widely prescribed in vertigo, is available only in immediate release dosage forms. The approved therapeutic dose and shorter elimination half-life make Meclizine HCl a potential candidate to be formulated in extended release dosage form. This study was aimed to develop extended release Meclizine HCl pellets by extrusion spheronization using natural and synthetic lipids. Influence of lipid type, drug/lipid ratio and combinations of different lipids on drug release and sphericity of pellets were evaluated. Thirty two formulations were prepared with four different lipids, Glyceryl monostearate (Geleol ® ), Glyceryl palmitostearate (Precirol ® ), Glyceryl behenate (Compritol ® ) and Carnauba wax, utilized either alone or in combinations of drug/lipid ratio of 1:0.5-1:3. Dissolution studies were performed at variable pH and release kinetics were analyzed. Fourier transform infrared spectroscopy was conducted and no drug lipid interaction was found. Sphericity indicated by shape factor (e R ) varied with type and concentration of lipids: Geleol ® (e R  = 0.891-0.997), Precirol ® (e R  = 0.611-0.743), Compritol ® (e R  = 0.665-0.729) and Carnauba wax (e R  = 0.499-0.551). Highly spherical pellets were obtained with Geleol ® (Aspect ratio = 1.005-1.052) whereas irregularly shaped pellets were formed using Carnauba wax (Aspect ratio = 1.153-1.309). Drug release was effectively controlled by three different combinations of lipids: (i) Geleol ® and Compritol ® , (ii) Geleol ® and Carnauba wax and (iii) Geleol ® , Compritol ® and Carnauba wax. Scanning electron microscopy of Compritol ® pellets showed smooth surface with pores, whereas, irregular rough surface with hollow depressions was observed in Carnauba wax pellets. Energy dispersive spectroscopy indicated elemental composition of lipid matrix pellets. Kinetics of (i) Geleol ® and Compritol ® pellets, explained by Korsmeyer-Peppas (R 2  = 0.978-0.993) indicated

  8. Vibratory-compacted (vipac/sphere-pac) nuclear fuels - a comparison with pelletized nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Chidester, K.; Rubin, J. [Los Alamos National Lab., NM (United States); Thompson, M

    2001-07-01

    In order to achieve the packing densities required for nuclear fuel stability, economy and performance, the fuel material must be densified. This has traditionally been performed by high-temperature sintering. (At one time, fuel densification was investigated using cold/hot swaging. However, this fabrication method has become uncommon.) Alternatively, fuel can be densified by vibratory compaction (VIPAC). During the late 1950's and into the 1970's, in the U.S., vibratory compaction fuel was fabricated and test irradiated to evaluate its applicability compared to the more traditional pelletized fuel for nuclear reactors. These activities were primarily focused on light water reactors (LWR) but some work was performed for fast reactors. This paper attempts to summarize these evaluations and proposes to reconsider VIPAC fuel for future use. (author)

  9. Vibratory-compacted (vipac/sphere-pac) nuclear fuels - a comparison with pelletized nuclear fuels

    International Nuclear Information System (INIS)

    Chidester, K.; Rubin, J.; Thompson, M.

    2001-01-01

    In order to achieve the packing densities required for nuclear fuel stability, economy and performance, the fuel material must be densified. This has traditionally been performed by high-temperature sintering. (At one time, fuel densification was investigated using cold/hot swaging. However, this fabrication method has become uncommon.) Alternatively, fuel can be densified by vibratory compaction (VIPAC). During the late 1950's and into the 1970's, in the U.S., vibratory compaction fuel was fabricated and test irradiated to evaluate its applicability compared to the more traditional pelletized fuel for nuclear reactors. These activities were primarily focused on light water reactors (LWR) but some work was performed for fast reactors. This paper attempts to summarize these evaluations and proposes to reconsider VIPAC fuel for future use. (author)

  10. Preparation and Properties of Agricultural Residuals-Iron Concentrate Pellets

    OpenAIRE

    Liu, Zhulin; Bi, Xuegong; Gao, Zeping; Wang, Yayu

    2017-01-01

    In this paper, carbon-containing pellets were prepared by using crop-derived charcoal made from agricultural residuals and iron ore concentrates, and their pelletizing performance and properties were studied. Experimental results showed that the strengths of pellets were related to the particle size of concentrates and the content of moisture, bentonite, and crop-derived charcoal fines in the pelletizing mixture and the temperature of roasting and reduction. That the granularity of raw materi...

  11. On the Drag Effect of a Refuelling Pellet

    DEFF Research Database (Denmark)

    Chang, Tinghong; Michelsen, Poul

    1981-01-01

    A refueling pellet is subjected mainly to two kinds of drags: (1) inertial drag caused by the motion of the pellet relative to the surrounding plasma, and (2) ablation drag caused by an uneven ablation rate of the front and the rear surface of the pellet in an inhomogeneous plasma. Computational...... results showed that for reasonable combinations of pellet size and injection speed, the drag effect is hardly detectable for plasma conditions prevailing in current large tokamaks....

  12. Measurement of shadowgraph of flying solid-hydrogen pellets

    International Nuclear Information System (INIS)

    Hasegawa, Kouichi; Kasai, Satoshi; Suzuki, Sadaaki; Oda, Yasushi.

    1992-11-01

    The measurement system of shadowgraphs of flying pellets for the high-speed multi-pellet injector is described. Shadowgraphs of pellets ejected repeatedly with 1-5 Hz could be taken with about 100 % probability by using the system, which is composed of a intense pulse-lamp with a video-camera and a timing control system. (author)

  13. Development and problems of pellet markets in Austria

    International Nuclear Information System (INIS)

    Nemestothy, K.P.; Rakos, C.

    2001-01-01

    Wood pellets became into Austrian markets in 1994. Up to then the Austrian industry had manufactured pellet fireplaces for export, but none was sold into Austria, because there were not pellets available in the Austrian markets. In spite of significant problems in the beginning and unfavourable economic conditions (decrease of oil prices) the pellet markets in Austria have increased since 1996 dynamically. Annual pellet deliveries have increased from 15 000 t/a to present 45 000 t/a. Customers and Austrian industry are interested in pellets and they believe in the future. The pellet manufacturing capacity increases continuously. In 1999 the capacity of 12 companies was 120 000 t. In 2003 the annual pellet consumption is estimated to over 100 000 tons and in 2010 about 200 000 tons. Main portion of the pellet manufactures in Austria is also used in the country by detached houses and small real estate houses. The pellet markets for large real estates are developing after the boiler manufacturers have started to produce pellet-fired equipment. The number of pellet-fired devices in 1997, sold to detached houses was 425, and in 2000 the number was 3500

  14. Apparatus for checking the dimensions of nuclear fuel pellets

    International Nuclear Information System (INIS)

    Marmo, A.R.

    1978-01-01

    The description is given of an apparatus for checking the dimensions of pellets comprising a housing, a feeding device near this housing to move a pellet towards the latter and away from it, and a platform with a hole, this platform being fitted to the housing near the feeding system in order to hold the pellet [fr

  15. Computerized x-ray radiographic system for fuel pellet measurements

    International Nuclear Information System (INIS)

    Green, D.R.; Karnesky, R.A.; Bromley, C.

    1977-01-01

    The development and operation of a computerized system for determination of fuel pellet diameters from x-ray radiography is described. Actual fuel pellet diameter measurements made with the system are compared to micrometer measurements on the same pellets, and statistically evaluated. The advantages and limitations of the system are discussed, and recommendations are made for further development

  16. Effects of carbonization conditions on properties of bamboo pellets

    Science.gov (United States)

    Zhijia Liu; Zehui Jiang; Zhiyong Cai; Benhua Fei; Yan Yu; Xing' e Liu

    2013-01-01

    Bamboo is a biomass material and has great potential as a bio-energy resource of the future in China. Bamboo pellets were successfully manufactured using a laboratory pellet mill in preliminary work. This study was therefore carried out to investigate the effect of carbonization conditions (temperature and time) on properties of bamboo pellets and to evaluate product...

  17. Global Wood Pellet Industry and Trade Study 2017

    NARCIS (Netherlands)

    Thrän, D.; Peetz, D.; Schaubach, K.; Mai-Moulin, T.; Junginger, H.M.; Lamers, P.; Visser, L.

    2017-01-01

    The report Global Wood Pellet Industry Market published in 2011 has always been the most downloaded document of IEA Bioenergy Task 40. We have decided to update the report and bring new insights on market trends and trade of the global wood pellets. The global wood pellet market has increased

  18. Particle fueling experiments with a series of pellets in LHD

    Science.gov (United States)

    Baldzuhn, J.; Damm, H.; Dinklage, A.; Sakamoto, R.; Motojima, G.; Yasuhara, R.; Ida, K.; Yamada, H.; LHD Experiment Group; Wendelstein 7-X Team

    2018-03-01

    Ice pellet injection is performed in the heliotron Large Helical Device (LHD). The pellets are injected in short series, with up to eight individual pellets. Parameter variations are performed for the pellet ice isotopes, the LHD magnetic configurations, the heating scenario, and some others. These experiments are performed in order to find out whether deeper fueling can be achieved with a series of pellets compared to single pellets. An increase of the fueling efficiency is expected since pre-cooling of the plasma by the first pellets within a series could aid deeper penetration of later pellets in the same series. In addition, these experiments show which boundary conditions must be fulfilled to optimize the technique. The high-field side injection of pellets, as proposed for deep fueling in a tokamak, will not be feasible with the same efficiency in a stellarator or heliotron because there the magnetic field gradient is smaller than in a tokamak of comparable size. Hence, too shallow pellet fueling, in particular in a large device or a fusion reactor, will be an issue that can be overcome only by extremely high pellet velocities, or other techniques that will have to be developed in the future. It turned out by our investigations that the fueling efficiency can be enhanced by the injection of a series of pellets to some extent. However, further investigations will be needed in order to optimize this approach for deep particle fueling.

  19. Fuel Pellets from Wheat Straw: The Effect of Lignin Glass Transition and Surface Waxes on Pelletizing Properties

    DEFF Research Database (Denmark)

    Stelte, Wolfgang; Clemons, Craig; Holm, Jens K.

    2012-01-01

    and a high concentration of hydrophobic waxes on its outer surface that may limit the pellet strength. The present work studies the impact of the lignin glass transition on the pelletizing properties of wheat straw. Furthermore, the effect of surface waxes on the pelletizing process and pellet strength...... are investigated by comparing wheat straw before and after organic solvent extraction. The lignin glass transition temperature for wheat straw and extracted wheat straw is determined by dynamic mechanical thermal analysis. At a moisture content of 8%, transitions are identified at 53°C and 63°C, respectively....... Pellets are pressed from wheat straw and straw where the waxes have been extracted from. Two pelletizing temperatures were chosen—one below and one above the glass transition temperature of lignin. The pellets compression strength, density, and fracture surface were compared to each other. Pellets pressed...

  20. Production and characterization of spodumene dosimetric pellets prepared by a sol–gel route

    International Nuclear Information System (INIS)

    Lima, H.R.B.R.; Nascimento, D.S.; Bispo, G.F.C.; Teixeira, V.C.; Valério, M.E.G.; Souza, S.O.

    2014-01-01

    Spodumene is an aluminosilicate that has shown good results for high-dose TL dosimetry for beta or gamma rays. Due to its chemical composition (LiAlSi 2 O 6 ) it has potential to be used as a neutron dosimeter. The synthetic spodumene is usually produced by solid state reaction and conventional sol–gel, whose shortcomings arise from the need to employ high temperatures and high cost reagents, respectively. Proteic sol–gel method is promising, because it can reduce production costs and the possibility of environmental contamination. This work reports the production of the spodumene by the proteic sol–gel method using edible unflavored gelatin as a precursor. The product is characterized physically and morphologically, and investigated its applicability as a TL dosimeter. Two sets of samples were prepared using different sources of silicon, one with TEOS (Si(OC 3 H 5 ) 4 ) and one with SILICA (SiO 2 ). The materials produced were characterized by X-ray diffraction, differential thermal analysis and thermogravimetry in order to evaluate the structural properties, as well as possible changes in physical or chemical properties depending on the temperature. The production of spodumene was successful, with generation of the crystals in the β-phase with tetragonal structure. Sintered pellets produced from these crystals were irradiated with a 90 Sr– 90 Y source and their TL glow curves were evaluated. Although the samples prepared by the proteic sol–gel method with TEOS presented a lower forming temperature, the samples produced with SILICA showed higher sensitivity to radiation. - Highlights: • β-spodumene can be successfully produced by the proteic sol–gel method. • Sintered pellets produced by the proteic sol–gel method are sensitive to beta rays. • β-spodumene produced by the proteic sol–gel method with SiO 2 is more sensitive to radiation detection than the one produced with TEOS

  1. U3O8 microspheres sintering kinetics

    International Nuclear Information System (INIS)

    Godoy, A.L.E.

    1986-01-01

    U 3 O 8 microspheres sintering kinetics was determined using a hot-stage optical microscopy apparatus, able to reach temperature up to 1350 0 C in controlled atmospheres. The sintered material had its microstructure analysed by optical and electron microscopy. The microspheres were characterized initialy utilizing X-ray diffractometry and thermogravimetry. The equation which describes the microspheres shrinkage in function of the time was obtained using finite difference analysis X-ray diffractometry indicated hexagonal structure for the microspheres main starting material, ammonium diuranate thermogravimetric analysis showed reduction of this material to U 3 O 8 at 600 0 C. Ceramography results showed 5 hours sintered microspheres grain sizes G vary with the temperature. Sintered U 3 O 8 micrographs compared with published results for UO 2 , indicate similar homogeneity microstructural characteristics and suggest the processed micorspheres to be potentially useful as nuclear fuels. (Author) [pt

  2. Optimization of backfill pellet properties AASKAR DP2 - Laboratory tests

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Linus; Sanden, Torbjoern [Clay Technology AB, Lund (Sweden)

    2012-12-15

    Bentonite pellets are planned to be used as a part of the backfill in the Swedish spent nuclear fuel deep repository concept KBS-3. This report describes testing and evaluation of different backfill pellet candidates. The work completed included testing of both pellet material and pellet type. The materials tested were sourced from India (ASHA), Greece (IBECO, 2 products) and Wyoming USA (MX-80 clay). The majority of the tests were completed on the ASHA clay as well as the IBECO-RWC-BF products, with only limited testing of the others. The pellets tested were manufactured using both extrusion and roller compaction techniques and had different sizes and geometries. The following tests have been performed and are presented in this report: 1. General tests. Water content, bulk density and dry density have been determined for both the pellet filling and the individual pellets. The compressibility of the pellet filling was tested with CRS-tests and the strength of the individual pellets was tested with a special compression test. The water content varied from 11.3% to 18.7% and was highest for the extruded pellets. The dry density was somewhat higher for the roller-compacted pellets and their compressibility was lower. The strength of the individual pellets was generally higher for the extruded pellets. 2. Erosion. The pellet filling will be exposed to groundwater inflow when installed in the tunnel. This flow could possibly cause significant erosion on the pellet filling. Erosion tests have been performed with comparisons in erosion resistance made on the various material- and pellet-types. The influence of variations in water salinity and flow rates was also tested. The IBECO extruded 6- and 10- mm diameter rods and the compacted Posiva spec.-A pellet filling seem to have the lowest tendency to erode. It is also the IBECO extruded pellet filling that withstands variations in water salinity and flow rates best. 3. Water storing capacity. The pellet filling

  3. Optimization of backfill pellet properties AASKAR DP2-Laboratory tests

    International Nuclear Information System (INIS)

    Andersson, Linus; Sanden, Torbjoern

    2012-12-01

    Bentonite pellets are planned to be used as a part of the backfill in the Swedish spent nuclear fuel deep repository concept KBS-3. This report describes testing and evaluation of different backfill pellet candidates. The work completed included testing of both pellet material and pellet type. The materials tested were sourced from India (ASHA), Greece (IBECO, 2 products) and Wyoming USA (MX-80 clay). The majority of the tests were completed on the ASHA clay as well as the IBECO-RWC-BF products, with only limited testing of the others. The pellets tested were manufactured using both extrusion and roller compaction techniques and had different sizes and geometries. The following tests have been performed and are presented in this report: 1. General tests. Water content, bulk density and dry density have been determined for both the pellet filling and the individual pellets. The compressibility of the pellet filling was tested with CRS-tests and the strength of the individual pellets was tested with a special compression test. The water content varied from 11.3% to 18.7% and was highest for the extruded pellets. The dry density was somewhat higher for the roller-compacted pellets and their compressibility was lower. The strength of the individual pellets was generally higher for the extruded pellets. 2. Erosion. The pellet filling will be exposed to groundwater inflow when installed in the tunnel. This flow could possibly cause significant erosion on the pellet filling. Erosion tests have been performed with comparisons in erosion resistance made on the various material- and pellet-types. The influence of variations in water salinity and flow rates was also tested. The IBECO extruded 6- and 10- mm diameter rods and the compacted Posiva spec.-A pellet filling seem to have the lowest tendency to erode. It is also the IBECO extruded pellet filling that withstands variations in water salinity and flow rates best. 3. Water storing capacity. The pellet filling's ability to

  4. Thermal barrier coating resistant to sintering

    Science.gov (United States)

    Subramanian, Ramesh; Seth, Brij B.

    2004-06-29

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process.

  5. Validation of the stamping method for CaSO{sub 4}:RE + Teflon® pellets production

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, Maira G.; Rodrigues, Leticia L.C., E-mail: mgnunes@ipen.br, E-mail: lcrodri@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2014-07-01

    The IPEN method for the CaSO{sub 4}:RE + Teflon® production, developed and patented at the Dosimetric Materials Laboratory - LMD/IPEN in the earlier 1980's, is highly time-demanding, so that the use of the stamping method, already widely industrially applied, would enhance the CaSO{sub 4}:RE + Teflon® pellets production. Thus, validating the stamping method, by comparing the dosimetric properties of a batch of pellets produced by each method, became a must. The stamped batch presents the same mean non-irradiated signals either after sintering or annealing while IPEN batch mean non-irradiated signals vary in 23%. The mean TL signal after irradiation was about 50 nC, but the standard deviation varies from 20% to 33% for IPEN batch and keeps in 10% for the stamped batch. 24 h after the irradiation, the TL signal decreased to about 35 nC, with no differences in IPEN batch standard deviation and a decrease to 5% in stamped batch standard deviation, for the five performed essays. Calibration curves present a linear behavior over the entire studied dose range and the same coefficients for both methods, however, the uncertainties in the coefficients determined to the calibration curve obtained with stamped pellets are significantly smaller, leading to a more precise dose determination. This results show that the stamping method produces more homogeneous batches, with pellets that maintain the dosimetric characteristics of the detectors produced by IPEN method, in such a way that the stamping method can substitute with advantages the IPEN method in the CaSO{sub 4}:RE + Teflon® dosimetric pellets production. (author)

  6. Profile of yttrium segregation in BaCe{sub 0,9}Y{sub 0,1}O{sub 3-{delta}} as function of sintering temperature; Perfil da segregacao do itrio em BaCe{sub 0,9}Y{sub 0,1}O{sub 3-{delta}} em funcao da temperatura de sinterizacao

    Energy Technology Data Exchange (ETDEWEB)

    Hosken, C.M.; Souza, D.P.F. de, E-mail: camila.hosken@gmail.co [Universidade Federal de Sao Carlos (LAPCEC/UFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais. Lab. de Preparacao e Caracterizacao Eletrica em Ceramicas

    2010-07-01

    Researches on solid oxide fuel cells indicate barium cerate perovskite as a very attractive material for using as electrolyte due to its high protonic conductivity. The objective of this work is investigate the yttrium segregation during sintering of BaCe{sub 0,9}Y{sub 0,1}O{sub 3-{delta}} doped with Zn O as a sintering aid. The powders were prepared by citrate process. Powders were isostatic pressed into pellets and sintered in air at 1200, 1275, 1325 and 1400 deg C. The samples were characterized by scanning electron microscopy, X-ray diffraction and impedance spectroscopy. Secondary phase containing Yttrium and Cerium was detected as sintering temperature increased. Increase of the lattice parameter and activation energy for electrical conductivity were also detected on samples sintered at 1400 deg C. (author)

  7. Novel compaction techniques with pellet-containing granules.

    Science.gov (United States)

    Pan, Xin; Chen, Meiwan; Han, Ke; Peng, Xinsheng; Wen, Xinguo; Chen, Bao; Wang, Jin; Li, Ge; Wu, Chuanbin

    2010-08-01

    The purpose of this investigation was to introduce a new concept of admixing coated pellets with excipients to obtain a segregation-free combination of pellet-containing granules and cushioning granules during mixing and compression. Acrylic polymeric-coated pellets were granulated by centrifugal granulation method with excipients; then, the pellet-containing granules were compacted into tablets with the cushioning granules, which were prepared in mixer or fluidized bed-granulator. Tablets were also made in a traditional method by directly compressing the mixtures of coated pellets and cushioning granules for control. Drug-release profiles, weights and drug content of tables were tested to compare this new method with the traditional method. The granulation process changed the surface morphology of coated pellets from smooth to rough and increased the angle of repose of pellets to close to that of the cushioning granules. Weight and drug content RSD values of tablets prepared by pellet-containing granules were much lower than those of tablets prepared by coated pellets. The similarity factor f(2) values for drug-release profiles of tablets prepared from pellet-containing granules and the original coated pellets were above 50 when microcrystalline cellulose (MCC), Polyplasdone(R) XL (PVPP), and lactose were used as granulating excipients. The granulation process could roughen the surface of coated pellets and increase the angle of repose and uniformity of the mixture with cushioning granules. Compared with the tablets directly compressed from coated pellets, the tablets prepared by pellet-containing granules showed improved uniformity in both weight and drug content. The granulation and compression processes did not significantly influence the drug-release behavior of coated pellets, and the enteric dissolution was retained.

  8. Fuel Pellets from Wheat Straw: The Effect of Lignin Glass Transition and Surface Waxes on Pelletizing Properties

    Science.gov (United States)

    Wolfgang Stelte; Craig Clemons; Jens K. Holm; Jesper Ahrenfeldt; Ulrik B. Henriksen; Anand R. Sanadi

    2012-01-01

    The utilization of wheat straw as a renewable energy resource is limited due to its low bulk density. Pelletizing wheat straw into fuel pellets of high density increases its handling properties but is more challenging compared to pelletizing wood biomass. Straw has a lower lignin content and a high concentration of hydrophobic waxes on its outer surface that may limit...

  9. Modeling Dynamic Fracture of Cryogenic Pellets

    Energy Technology Data Exchange (ETDEWEB)

    Parks, Paul [General Atomics, San Diego, CA (United States)

    2016-06-30

    This work is part of an investigation with the long-range objective of predicting the size distribution function and velocity dispersion of shattered pellet fragments after a large cryogenic pellet impacts a solid surface at high velocity. The study is vitally important for the shattered pellet injection (SPI) technique, one of the leading technologies being implemented at ORNL for the mitigation of disruption damage on current tokamaks and ITER. The report contains three parts that are somewhat interwoven. In Part I we formulated a self-similar model for the expansion dynamics and velocity dispersion of the debris cloud following pellet impact against a thick (rigid) target plate. Also presented in Part I is an analytical fracture model that predicts the nominal or mean size of the fragments in the debris cloud and agrees well with known SPI data. The aim of Part II is to gain an understanding of the pellet fracturing process when a pellet is shattered inside a miter tube with a sharp bend. Because miter tubes have a thin stainless steel (SS) wall a permanent deformation (dishing) of the wall is produced at the site of the impact. A review of the literature indicates that most projectile impact on thin plates are those for which the target is deformed and the projectile is perfectly rigid. Such impacts result in “projectile embedding” where the projectile speed is reduced to zero during the interaction so that all the kinetic energy (KE) of the projectile goes into the energy stored in plastic deformation. Much of the literature deals with perforation of the target. The problem here is quite different; the softer pellet easily undergoes complete material failure causing only a small transfer of KE to stored energy of wall deformation. For the real miter tube, we derived a strain energy function for the wall deflection using a non-linear (plastic) stress-strain relation for 304 SS. Using a dishing profile identical to the linear Kirchkoff-Love profile (for lack

  10. Pelletization processes for pharmaceutical applications: a patent review.

    Science.gov (United States)

    Politis, Stavros N; Rekkas, Dimitrios M

    2011-01-01

    Pellets exhibit major therapeutic and technical advantages which have established them as an exceptionally useful dosage form. A plethora of processes and materials is available for the production of pellets, which practically allows inexhaustible configurations contributing to the flexibility and versatility of pellets as drug delivery systems. The scope of this review is to summarize the recent literature on pelletization processes for pharmaceutical applications, focusing on the awarded and pending patents in this technical field. The first part of the article provides an overview of innovation in pelletization processes, while the second part evaluates their novel applications.

  11. Study of the pelletizing process zirconium oxide and zircon sand

    International Nuclear Information System (INIS)

    Seo, E.S.M.; Paschoal, J.O.A.; Acevedo, M.T.P.

    1990-12-01

    The study of the process to obtain zirconium tetrachloride under development at IPEN, can be divide into two steps: pelletizing and chlorination. Pelletizing is an important step in the overall process as it facilitates greater contact between the particles and permits the production of pellets with dimensional uniformity and mechanical strength. In this paper, the results of the study of pelletizing zirconium oxide and zircon sand are presented. The influence of some variables related to the process and the equipment on the physical characteristics of the pellets are discussed. (author)

  12. Analysis of Laser Sintering Technology

    Directory of Open Access Journals (Sweden)

    Vladislav Markovič

    2014-02-01

    Full Text Available The new, high-tech development and customization is one ofthe most important factors in promoting the country‘s economicgrowth indicators. The economic downturn in the industryrequires technology and equipment using a minimumof raw materials and providing maximum performance. Thisstatement perfectly describes the innovative, forward-looking,cost-effective laser powder sintering (SLS technology. Here,thanks to the latest engineering achievements, product surfacesare modified and improved, they gain new characteristics. SLSis viable in automobile, engineering, construction, aerospace,aircraft, printing, medical and other areas.In order to create a product which meets the standards andtechnical documentation it is necessary to use and ensure highquality of raw materials, high-end equipment, qualified personnel,the working environment with proper climatic conditions, ergonomics,etc. But all of these, the quality of the product becomesthe decisive indicators meaningless if know how to properly selectthe laser processing operation. Scanning speed, beam power,pulse frequency, protective gases, powder layer thickness – allof them are the physical and mechanical characteristics of thechange in a small range changes the quality of the product of thefuture, the field of application and performance characteristics.

  13. Spherical Demons: Fast Surface Registration

    Science.gov (United States)

    Yeo, B.T. Thomas; Sabuncu, Mert; Vercauteren, Tom; Ayache, Nicholas; Fischl, Bruce; Golland, Polina

    2009-01-01

    We present the fast Spherical Demons algorithm for registering two spherical images. By exploiting spherical vector spline interpolation theory, we show that a large class of regularizers for the modified demons objective function can be efficiently implemented on the sphere using convolution. Based on the one parameter subgroups of diffeomorphisms, the resulting registration is diffeomorphic and fast – registration of two cortical mesh models with more than 100k nodes takes less than 5 minutes, comparable to the fastest surface registration algorithms. Moreover, the accuracy of our method compares favorably to the popular FreeSurfer registration algorithm. We validate the technique in two different settings: (1) parcellation in a set of in-vivo cortical surfaces and (2) Brodmann area localization in ex-vivo cortical surfaces. PMID:18979813

  14. Characterization of crystalline phases of (U,Er)O2 pellets by X-Ray diffraction

    International Nuclear Information System (INIS)

    Sansone, Alberto E.S.; Riella, Humberto G.; Carvalho, Elita F. U. de

    2017-01-01

    Optimization of nuclear fuel for use in pressurized water reactors can be achieved by obtaining higher burnups. This, however, requires the excess reactivity caused by increasing the fuel's enrichment to be taken into account, which can be done by introducing burnable absorbers into the UO 2 fuel pellets themselves. Some of the rare earth elements have thermal and mechanical properties that make them appropriate for use inside the reactor. In order to characterize the microstructure of erbium-doped UO 2 fuel, sintered UO 2 -Er 2 O 3 pellets were prepared, with Er 2 O 3 content ranging from 1:0 to 9:8wt%, and analyzed by X-ray diffraction to determine whether the composite formed solid solutions and, if so, evaluate the lattice parameter as a function of erbia concentration. While XRD analysis showed the Er 2 O 3 completely dissolved in the UO 2 powder, it also evidenced the emergence of a second fluorite-type phase, whose phase fraction increases and lattice parameter decreases with increasing erbia concentration. Analysis of the diffraction patterns showed this emerging phase has the same crystalline structure as the host lattice, but with a smaller lattice parameter, and a smaller domain size. These results are compatible with the phenomenon of defect segregation, which consists in the formation of microdomains with a higher concentration of defects. (author)

  15. Fabrication of uranium-americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    Science.gov (United States)

    Remy, E.; Picart, S.; Delahaye, T.; Jobelin, I.; Lebreton, F.; Horlait, D.; Bisel, I.; Blanchart, P.; Ayral, A.

    2014-10-01

    Mixed uranium-americium oxides are one of the materials envisaged for Americium Bearing Blankets dedicated to transmutation in fast neutron reactors. Recently, several processes have been developed in order to validate fabrication flowchart in terms of material specifications such as density and homogeneity but also to suggest simplifications for lowering industrial costs and hazards linked to dust generation of highly contaminating and irradiating compounds. This study deals with the application of an innovative route using mixed oxide microspheres obtained from metal loaded resin bead calcination, called Calcined Resin Microsphere Pelletization (CRMP). The synthesis of mixed oxide microsphere precursor of U0.9Am0.1O2±δ is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U0.9Am0.1O2±δ. The ceramic obtained was characterised and results showed that its microstructure is dense and homogeneous and its density attains 95% of the theoretical density. This study validates the scientific feasibility of the CRMP process applied to the fabrication of uranium and americium-containing materials.

  16. An advanced cold moderator using solid methane pellets

    International Nuclear Information System (INIS)

    Foster, C.A.; Carpenter, J.M.

    2001-01-01

    This paper reports developments of the pellet formation and transport technologies required for producing a liquid helium or hydrogen cooled methane pellet moderator. The Phase I US DOE SBIR project, already completed, demonstrated the production of 3 mm transparent pellets of frozen methane and ammonia and transport of the pellets into a 40 cc observation cell cooled with liquid helium. The methane pellets, formed at 72 K, stuck together during the loading of the cell. Ammonia pellets did not stick and fell readily under vibration into a packed bed with a 60% fill fraction. A 60% fill fraction should produce a very significant increase in long-wavelength neutron production and advantages in shorter pulse widths as compared to a liquid hydrogen moderator. The work also demonstrated a method of rapidly changing the pellets in the moderator cell. The Phase II project, just now underway, will develop a full-scale pellet source and transport system with a 1.5 L 'moderator' cell. The Phase II effort will also produce an apparatus to sub-cool the methane pellets to below 20 K, which should prevent the methane pellets from sticking together. In addition to results of the phase I experiments, the presentation includes a short video of the pellets, and a description of plans for the Phase II project. (author)

  17. Performance characterization of pneumatic single pellet injection system

    International Nuclear Information System (INIS)

    Schuresko, D.D.; Milora, S.L.; Hogan, J.T.; Foster, C.A.; Combs, S.K.

    1982-01-01

    The Oak Ridge National Laboratory single-shot pellet injector, which has been used in plasma fueling experiments on ISX and PDX, has been upgraded and extensively instrumented in order to study the gas dynamics of pneumatic pellet injection. An improved pellet transport line was developed which utilizes a 0.3-cm-diam by 100-cm-long guide tube. Pellet gun performance was characterized by measurements of breech and muzzle dynamic pressures and by pellet velocity and mass determinations. Velocities up to 1.4 km/s were achieved for intact hydrogen pellets using hydrogen propellant at 5-MPa breech pressure. These data have been compared with new pellet acceleration calculations which include the effects of propellant friction, heat transfer, time-dependent boundary conditions, and finite gun geometry. These results provide a basis for the extrapolation of present-day pneumatic injection system performance to velocities in excess of 2 km/s

  18. Pellet refuelling of the ZT-40M reversed field pinch

    International Nuclear Information System (INIS)

    Wurden, G.A.; Weber, P.G.; Watt, R.G.; Munson, C.P.; Ingraham, J.C.; Howell, R.B.; Clayton, T.E.; Buechl, K.; Nilles, E.J.

    1987-01-01

    The first pellet refuelling of a reversed field pinch has been successfully demonstrated in ZT-40M. By injecting a series of pellets, density increases of 600% have been observed, with no disruptions. Because of a coincidence of pellet transit time, Ohmic reheat time and particle confinement times (about 0.5 ms) a significant fraction of the plasma inventory 'leaks out' before pellet ablation is complete. Strong on-axis peaking of the density profile due to pellet fuelling is not typically observed; this is due to large poloidal and toroidal deflections observed in the pellet trajectory, beginning in the plasma edge. Asymmetric ablation of the pellet by a suprathermal electron population is suspected and simple modelling can account for the observed trajectories. (author)

  19. Reprint of: Pelletizing properties of torrefied wheat straw

    DEFF Research Database (Denmark)

    Stelte, Wolfgang; Nielsen, Niels Peter K.; Hansen, Hans Ove

    2013-01-01

    Combined torrefaction and pelletization are used to increase the fuel value of biomass by increasing its energy density and improving its handling and combustion properties. However, pelletization of torrefied biomass can be challenging and in this study the torrefaction and pelletizing properties...... of wheat straw have been analyzed. Laboratory equipment has been used to investigate the pelletizing properties of wheat straw torrefied at temperatures between 150 and 300 °C. IR spectroscopy and chemical analyses have shown that high torrefaction temperatures change the chemical properties of the wheat...... straw significantly, and the pelletizing analyses have shown that these changes correlate to changes in the pelletizing properties. Torrefaction increase the friction in the press channel and pellet strength and density decrease with an increase in torrefaction temperature....

  20. Gravitational Field of Spherical Branes

    Science.gov (United States)

    Gogberashvili, Merab

    The warped solution of Einstein's equations corresponding to the spherical brane in five-dimensional AdS is considered. This metric represents interiors of black holes on both sides of the brane and can provide gravitational trapping of physical fields on the shell. It is found that the analytic form of the coordinate transformations from the Schwarzschild to co-moving frame that exists only in five dimensions. It is shown that in the static coordinates active gravitational mass of the spherical brane, in agreement with Tolman's formula, is negative, i.e. such objects are gravitationally repulsive.

  1. Spherical agglomeration of acetylsalicylic acid

    Directory of Open Access Journals (Sweden)

    Polowczyk Izabela

    2016-01-01

    Full Text Available In this paper spherical agglomeration of acetylsalicylic acid was described. In the first step, the system of good and poor solvents as well as bridging liquid was selected. As a result of a preliminary study, ethyl alcohol, water and carbon tetrachloride were used as the good solvent, poor one, and bridging liquid, respectively. Then, the amount of acetylsalicylic acid and the ratio of the solvents as well as the volume of the bridging liquid were examined. In the last step, the agglomeration conditions, such as mixing intensity and time, were investigated. The spherical agglomerates obtained under optimum conditions could be subjected to a tableting process afterwards.

  2. Discrimination symbol applying method for sintered nuclear fuel product

    International Nuclear Information System (INIS)

    Ishizaki, Jin

    1998-01-01

    The present invention provides a symbol applying method for applying discrimination information such as an enrichment degree on the end face of a sintered nuclear product. Namely, discrimination symbols of information of powders are applied by a sintering aid to the end face of a molded member formed by molding nuclear fuel powders under pressure. Then, the molded product is sintered. The sintering aid comprises aluminum oxide, a mixture of aluminum oxide and silicon dioxide, aluminum hydride or aluminum stearate alone or in admixture. As an applying means of the sintering aid, discrimination symbols of information of powders are drawn by an isostearic acid on the end face of the molded product, and the sintering aid is sprayed thereto, or the sintering aid is applied directly, or the sintering aid is suspended in isostearic acid, and the suspension is applied with a brush. As a result, visible discrimination information can be applied to the sintered member easily. (N.H.)

  3. Solid-state sintering of tungsten heavy alloys

    International Nuclear Information System (INIS)

    Gurwell, W.E.

    1994-10-01

    Solid-state sintering is a technologically important step in the fabrication of tungsten heavy alloys. This work addresses practical variables affecting the sinterability: powder particle size, powder mixing, and sintering temperature and time. Compositions containing 1 to 10 micrometer (μM) tungsten (W) powders can be fully densified at temperatures near the matrix solidus. Blending with an intensifier bar provided good dispersion of elemental powders and good as-sintered mechanical properties under adequate sintering conditions. Additional ball milling increases powder bulk density which primarily benefits mold and die filling. Although fine, 1 μm W powder blends have high sinterability, higher as-sintered ductilities are reached in shorter sintering times with coarser, 5 μm W powder blends; 10μm W powder blends promise the highest as-sintered ductilities due to their coarse microstructural W

  4. On the pelletizing of sulfide molybdenite concentrate

    International Nuclear Information System (INIS)

    Palant, A.A.

    2007-01-01

    Investigation results are discussed on the process of pelletizing with the use of various binders (water, syrup, sulfite-alcoholic residue and bentonite) for flotation sulfide molybdenite concentrate (∼84 % MoS 2 ) of the Mongolian deposit. It is established that with the use of syrup rather strong pellets (>300 g/p) of desired size (2-3 mm) can be obtained at a binder flowrate of 1 kg per 100 kg of concentrate. The main advantage of using syrup instead of bentonite lies in the fact that in this instance no depletion of a molybdenum calcine obtained by oxidizing roasting of raw ore takes place due to syrup complete burning out. This affects positively subsequent hydrometallurgical conversion because of decreasing molybdenum losses with waste cakes [ru

  5. Tritium pellet injection sequences for TFTR

    International Nuclear Information System (INIS)

    Houlberg, W.A.; Milora, S.L.; Attenberger, S.E.; Singer, C.E.; Schmidt, G.L.

    1983-01-01

    Tritium pellet injection into neutral deuterium, beam heated deuterium plasmas in the Tokamak Fusion Test Reactor (TFTR) is shown to be an attractive means of (1) minimizing tritium use per tritium discharge and over a sequence of tritium discharges; (2) greatly reducing the tritium load in the walls, limiters, getters, and cryopanels; (3) maintaining or improving instantaneous neutron production (Q); (4) reducing or eliminating deuterium-tritium (D-T) neutron production in non-optimized discharges; and (5) generally adding flexibility to the experimental sequences leading to optimal Q operation. Transport analyses of both compression and full-bore TFTR plasmas are used to support the above observations and to provide the basis for a proposed eight-pellet gas gun injector for the 1986 tritium experiments

  6. Deuterium pellet injection in the TFR Tokamak

    International Nuclear Information System (INIS)

    Lazare, O.

    1985-07-01

    Injecting fresh fuel deep inside the plasma of a thermonuclear reactor appears to be necessary; the only way to do that is to inject fast solid deuterium pellets. The existing theoretical, technical and experimental aspects of this method are presented. The experiments on TFR have confirmed that injecting pellets is technically feasible; a new kind of injector is presented. The injection does not degrade stability nor confinement of the plasma. The study of the transient phenomena occuring during the injection has proved to be an efficient way to investigate particles and energy transport in the discharge; in particular, a fast transport phenomenon, similar to those occuring during disruptions, has been studied in details. Conclusions about disruptions are drawn. (Ref 101) [fr

  7. Advanced fuel pellet materials and designs for water cooled reactors. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    2004-10-01

    with the technological advances attempted in doping of fuel pellets with the primary objective of obtaining larger grains. While most of the papers gave an account of the experimental studies on addition of various dopants in different fuel materials, some of them outlined the behaviour of such pellets at sintering process. Papers dealing with 'Fission gas release from fuel pellets under high burnup conditions were presented in Session 3. Session 4 was devoted to the evolution of fuel pellet structure and thermal properties at high burnup. Session 5 was dealing with fuel pellet-cladding interaction (PCI) being a complex phenomenon that may lead to cladding failure and subsequent release of fission products into the reactor coolant. Research efforts to understand better the PCI phenomenon and minimize it with design solutions are considered necessary

  8. Fabrication of uranium–americium mixed oxide pellet from microsphere precursors: Application of CRMP process

    Energy Technology Data Exchange (ETDEWEB)

    Remy, E. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Picart, S., E-mail: sebastien.picart@cea.fr [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Delahaye, T. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Jobelin, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Lebreton, F.; Horlait, D. [Fuel Cycle Technology Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Bisel, I. [Radiochemistry and Processes Department, CEA, Nuclear Energy Division, F-30207 Bagnols-sur-Cèze (France); Blanchart, P. [Heterogeneous Materials Research Group, Centre Européen de la Céramique, F-87068 Limoges (France); Ayral, A. [Institut Européen des Membranes, CNRS-ENSCM-UM2, CC47, University Montpellier 2, F-34095 Montpellier cedex 5 (France)

    2014-10-15

    Highlights: • Dust free process for (U,Am)O{sub 2} transmutation target fabrication. • Synthesis of U{sub 0.9}Am{sub 0.1}O{sub 2} mixed oxide microspheres from ion exchange resin. • Fabrication of dense U{sub 0.9}Am{sub 0.1}O{sub 2} pellet with 95% TD from mixed oxide microspheres. - Abstract: Mixed uranium–americium oxides are one of the materials envisaged for Americium Bearing Blankets dedicated to transmutation in fast neutron reactors. Recently, several processes have been developed in order to validate fabrication flowchart in terms of material specifications such as density and homogeneity but also to suggest simplifications for lowering industrial costs and hazards linked to dust generation of highly contaminating and irradiating compounds. This study deals with the application of an innovative route using mixed oxide microspheres obtained from metal loaded resin bead calcination, called Calcined Resin Microsphere Pelletization (CRMP). The synthesis of mixed oxide microsphere precursor of U{sub 0.9}Am{sub 0.1}O{sub 2±δ} is described as well as its characterisation. The use of this free-flowing precursor allows the pressing and sintering of one pellet of U{sub 0.9}Am{sub 0.1}O{sub 2±δ}. The ceramic obtained was characterised and results showed that its microstructure is dense and homogeneous and its density attains 95% of the theoretical density. This study validates the scientific feasibility of the CRMP process applied to the fabrication of uranium and americium-containing materials.

  9. Fuel pellets from biomass: The importance of the pelletizing pressure and its dependency on the processing conditions

    DEFF Research Database (Denmark)

    Stelte, Wolfgang; Holm, Jens K.; Sanadi, Anand R.

    2011-01-01

    The aim of the present study was to identify the key factors affecting the pelletizing pressure in biomass pelletization processes. The impact of raw material type, pellet length, temperature, moisture content and particle size on the pressure build up in the press channel of a pellet mill...... act as lubricants, lowering the friction between the biomass and the press channel walls. The effect of moisture content on the pelletizing pressure was dependent on the raw material species. Different particle size fractions, from below 0.5 mm up to 2.8 mm diameter, were tested, and it was shown...

  10. Multi-pellet injection on Jet

    International Nuclear Information System (INIS)

    Kupschus, P.; Cheetham, A.; Denne, B.; Gadeberg, M.; Gowers, C.; Gondhalekar, A.; Tubbing, B.; Schissel, D.

    1989-01-01

    The investigations carried out with the JET multi-pellet injector are presented. The results show that with central deposition, peaked density profiles with central values exceeding 10 20 /m 3 can be reached. These peaked profiles can persist for times of the order of seconds. Auxiliary heating seems to accelerate the slow central density decay; it is also observed that high electron pressure values are generated in a core with a high D-D reaction rate

  11. Pellet to Part Manufacturing System for CNCs

    Energy Technology Data Exchange (ETDEWEB)

    Roschli, Alex C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Love, Lonnie J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Post, Brian K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chesser, Phillip C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lloyd, Peter D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bandari, Yashwanth Kumar [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jones, Jason [Hybrid Manufacturing Technologies, Swadlincote (United Kingdom); Gaul, Katherine T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2018-03-14

    Oak Ridge National Laboratory’s Manufacturing Demonstration Facility worked with Hybrid Manufacturing Technologies to develop a compact prototype composite additive manufacturing head that can effectively extrude injection molding pellets. The head interfaces with conventional CNC machine tools enabling rapid conversion of conventional machine tools to additive manufacturing tools. The intent was to enable wider adoption of Big Area Additive Manufacturing (BAAM) technology and combine BAAM technology with conventional machining systems.

  12. Summary of fueling by pellet injection

    International Nuclear Information System (INIS)

    Stewart, L.D.

    1978-01-01

    Model-based studies were presented which indicated in all cases that shielding will occur, but there was not total agreement in these studies on the mechanism of the shielding. The data from the pellet ablation experiment on ORMAK was explained by considering the plasma electron flux, incident on the pellet surface, to create an ablated neutral cloud which self-consistently attenuates the incident electron flux. The lack of total agreement in the studies comes about when extending this to tokamak reactor plasmas. Various groups contended either that this mechanism would continue to dominate in reactor plasmas, or that it would be modified by a comparable heat flux from alphas, or that it would be modified somewhat by electrostatic shielding because of electron flux induced charge buildup on the pellet, or that it would be modified by ionization of the neutral cloud yielding a plasma cloud shield, or that this same plasma cloud would exclude magnetic field causing deflection of the incident electron flux and therefore additional shielding

  13. Shattered Pellet Injection Simulations With NIMROD

    Science.gov (United States)

    Kim, Charlson; Parks, Paul; Lao, Lang; Lehnan, Michael; Loarte, Alberto; Izzo, Valerie; Nimrod Team

    2017-10-01

    Shattered Pellet Injection (SPI) will be the Disruption Mitigation System in ITER. SPI propels a cryo-pellet of high-Z and deuterium into a sharp bend of the flight tube, shattering the pellet into a plume of shards. These shards are injected into the plasma to quench it and mitigate forces and heat loads that may damage in-vessel components. We use NIMROD to perform 3-D nonlinear MHD simulations of SPI to study the thermal quench. This work builds upon prior Massive Gas Injection (MGI) studies by Izzo. A Particle-in-Cell (PIC) model is implemented to mimic the shards, providing a discrete moving source. Observations indicate that the quench proceeds in two phases. Initially, the outer plasma is shed via interchange-like instabilities while preserving the core temperature. This results in a steep gradient and triggers the second phase, an external kink-like event that collapses the core. We report on the radiation efficiency and toroidal peaking as well as fueling efficiency and other metrics that assess the efficacy of the SPI system. Work supported by GA ITER Contract ITER/CT/14/4300001108 and US DOE DE-FG02-95ER54309.

  14. Properties of pellet cement-glass package

    International Nuclear Information System (INIS)

    Chino, K.; Izumida, T.

    1989-01-01

    A new solidification technique using cement-glass, which is a mixture of sodium silicate, silicon phosphate and cement is presented. It was developed to solidify sodium sulfate or sodium borate pellets generated from nuclear power plants. The optimum composition of Na 2 O, SiO 2 and P 2 O 5 · 2SiO 2 , main components of cement-glass, was defined to be 1:2:1 by studying the solidification mechanism. Polymer impregnated concrete was selected as material of the container to increase the stability. Since the package consists of inorganic materials, it shows good fire resistance and radiation stability. Added cement absorbs free water which is generated by the solidification reaction of Na 2 O, SiO 2 and P 2 O 5 · 2SiO 2 . Then, soluble pellets can be solidified without dissolving some part of them. Since polymer impregnated concrete has little porosity, the pellet cement-glass package which uses a polymer impregnated concrete container shows very low leachability

  15. The UO{sub 2} pellets plant experimental background of the established process; La Planta de Fabricacion de Pastillas de UO{sub 2} Bases Experimentales del proceso establecido

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio Arroyo, E.; Alonso Folgueras, J. A.

    1969-07-01

    An account of the UO{sub 2} research and development carried out at the JEN is first given. This includes a 10 tons/year pellet Plant construction. Experimental background of the process is established, pointing out both milling advantages and risks, granulation devices, automatic press selection, binder removing and sintering furnaces. Origin, surface area, grain size and 0/U rate are considered as raw material reception parameters, although this process shows a wide scope. (Author) 13 refs.

  16. Experimental study of the evaporation and expansion of a solid pellet in a plasma heated by an electron beam

    International Nuclear Information System (INIS)

    Akent'ev, R.Yu.; Arzhannikov, A.V.; Astrelin, V.T.; Burdakov, A.V.; Ivanov, I.A.; Kojdan, V.S.; Mekler, K.I.; Polosatkin, S.V.; Postupaev, V.V.; Rovenskikh, A.F.; Sinitskij, S.L.

    2004-01-01

    The results of experiments on the solid pellets injection into the plasma, heated by an electron beam at the GOL-3 facility, are presented. The polyethylene pellets with the mass of 0.1-1 mg and lithium deuteride pellets with the mass of 0.02-0.5 mg were used. The dense plasma bunch, scattering at first spherically, is formed during several microseconds after the beginning of the electron beam injection into the plasma. Thereafter the bunch periphery is heated and becomes magnetized. Further there takes place the expansion of the dense plasma along the magnetic field on the order of 300 km/s. Comparison of the observed values with the calculations by the hydrodynamic model indicates, that for explaining such a rate of the bunch expansion the density of the total energy, falling on the pellet, should be ∼1 kJ/cm 2 . This value exceeds the corresponding value for the main plasma, i.e. there is observed the energy concentration across the magnetic field into the dense bunch of the evaporated macroparticle [ru

  17. New pellet production and acceleration technologies for high speed pellet injection system 'HIPEL' in large helical device

    International Nuclear Information System (INIS)

    Viniar, I.; Sudo, S.

    1994-12-01

    New technologies of pellet production and acceleration for fueling and diagnostics purposes in large thermonuclear reactors are proposed. The technologies are intended to apply to the multiple-pellet injection system 'HIPEL' for Large Helical Device of NIFS in Japan. The pellet production technology has already been tested in a pipe-gun type pellet injector. It will realize the repeating pellet injection by means of decreasing of the pellet formation time into the pipe-gun barrel. The acceleration technology is based upon a new pump tube operation in two-stage gas gun and also upon a new conception of the allowable pressure acting on a pellet into a barrel. Some preliminary estimations have been made, and principles of a pump tube construction providing for a reliable long term operation in the repeating mode without any troubles from a piston are proposed. (author)

  18. Producing bio-pellets from sunflower oil cake for use as an energy source

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Yuichi; Kato, Hitoshi; Kanai, Genta; Togashi, Tatsushi [National Agricultural Research Center (Japan)], E-mail: kobay@affrc.go.jp

    2008-07-01

    Pellet fuels were produced from ground sunflower oil cake using a pelletizer. The length, hardness, and powder characteristics of dried pellets depend on the initial water content of the oil cake. The appropriate values of water contents were 19.9 - 21.0% w.b. Oil cake pellets were found to contain 6.07% ash and 20.99 MJ/kg caloric value, which are within the standard range of wood pellets. Combustion experiments using a commercial pellet stove demonstrate that oil cake pellets burn as well as wood pellets. Oil cake pellets are useful as a fuel alternative to wood pellets. (author)

  19. Effects of sintering atmosphere and initial particle size on sintering of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    Batista, Rafael Morgado

    2014-01-01

    The effects of the sintering atmosphere and initial particle size on the sintering of ceria containing 10 mol% gadolinia (GdO 1.5 ) were systematically investigated. The main physical parameter was the specific surface area of the initial powders. Nanometric powders with three different specific surface areas were utilized, 210 m 2 /g, 36,2 m 2 /g e 7,4 m 2 /g. The influence on the densification, and micro structural evolution were evaluated. The starting sintering temperature was verified to decrease with increasing on the specific surface area of raw powders. The densification was accelerated for the materials with smaller particle size. Sintering paths for crystallite growth were obtained. Master sintering curves for gadolinium-doped ceria were constructed for all initial powders. A computational program was developed for this purpose. The results for apparent activation energy showed noticeable dependence with specific surface area. In this work, the apparent activation energy for densification increased with the initial particle size of powders. The evolution of the particle size distributions on non isothermal sintering was investigated by WPPM method. It was verified that the grain growth controlling mechanism on gadolinia doped ceria is the pore drag for initial stage and beginning of intermediate stage. The effects of the sintering atmosphere on the stoichiometry deviation of ceria, densification, microstructure evolution, and electrical conductivity were analyzed. Inert, oxidizing, and reducing atmospheres were utilized on this work. Deviations on ceria stoichiometry were verified on the bulk materials. The deviation verified was dependent of the specific surface area and sintering atmosphere. Higher reduction potential atmospheres increase Ce 3+ bulk concentration after sintering. Accelerated grain growth and lower electrical conductivities were verified when reduction reactions are significantly present on sintering. (author)

  20. Master sintering curve: A practical approach to its construction

    Directory of Open Access Journals (Sweden)

    Pouchly V.

    2010-01-01

    Full Text Available The concept of a Master Sintering Curve (MSC is a strong tool for optimizing the sintering process. However, constructing the MSC from sintering data involves complicated and time-consuming calculations. A practical method for the construction of a MSC is presented in the paper. With the help of a few dilatometric sintering experiments the newly developed software calculates the MSC and finds the optimal activation energy of a given material. The software, which also enables sintering prediction, was verified by sintering tetragonal and cubic zirconia, and alumina of two different particle sizes.