WorldWideScience

Sample records for absorber pellets

  1. Results of post-irradiation examinations of the absorber NS 201 (with pellets) of the KNK II first core

    The absorber NS-201 of the KNK II first core has been unloaded after a residence time of 273 equivalent full-power days, because gap closure between pellet and cladding had to be expected in 24 pins with B4C-pellets. Selected pins of this element underwent post-irradiation examinations in the hot cells of the KfK Karlsruhe. The evaluated and interpreted results of the investigations, which are documented in this report, allow the conclusion that the absorber could have been irradiated for the full core residence time. The good irradiation behaviour of the pellets and the cladding without any visible interaction, lead to the plan for further irradiation of a complete pellet column of one pin in the third core of KNK II

  2. A study on the oxidation characteristic of UO{sub 2}-Gd{sub 2}O{sub 3} pellet for recycling of burnable absorber pellet scrap

    Kim, K. S.; Song, K. W.; Kang, K. W.; Yang, J. H.; Kim, J. H

    2001-04-01

    The development of recycling process of defective (U,Gd)O{sub 2} scrap is one of the important subject in this project. Among the several burnable absorbers, Gd has a very large neutron absorption cross-section. Therefore, gadolinia bearing UO{sub 2} fuel, (U,Gd)O{sub 2}, has been widely used as a burnable absorber in light water reactors. During the pellet fabrication process, fairly amount of defective (U,Gd)O{sub 2} pellets are produced and it is necessary to recycle the scraps. Generally, the defective scraps are powdered through the oxidation in air in the temperature range of 450 to 550 deg C and then mixed with co-milled powder, and further processed to fabricate (U,Gd)O{sub 2} pellets. In addition, the sintered pellet properties are closely depend on the powder property of oxidized M{sub 3}O{sub 8} powder. Therefore, the careful investigate of oxidation kinetics and related powder property of (U,Gd)O{sub 2} is very important. The oxidation behavior of UO{sub 2}-6wt% Gd{sub 2}O{sub 3} and UO{sub 2}-12wt% Gd{sub 2}O{sub 3} has been studied in the temperature range from 350 to 700 deg C using TGA and XRD techniques in air. UO{sub 2} was necessarily oxidized to U{sub 3}O{sub 8} regardless of oxidation temperature and its weight gain was 4wt%. However, (U,Gd)O{sub 2} exhibit a different oxidation behavior ; The final phase and saturated weight gain depends on oxidation temperature. The saturated weight gain increases with oxidation temperature up to 500deg C and thereafter decreases with temperature. In addition, the amount of weight gain obtained at 500 deg C was smaller in UO{sub 2}-12wt% Gd{sub 2}O{sub 3} than in UO{sub 2}-6wt% Gd{sub 2}O{sub 3} and the final phase at the saturated weight gain was M{sub 3}O{sub 8} in UO{sub 2}-6wt% Gd{sub 2}O{sub 3} but the mixture of M{sub 4}O{sub 9} and M{sub 3}O{sub 8} in UO{sub 2}-12wt% Gd{sub 2}O{sub 3}. It is supposed that Gd substitution for U decreases the equilibrium O/M ratio and thereby enhance the stability of M

  3. A study on the oxidation characteristic of UO2-Gd2O3 pellet for recycling of burnable absorber pellet scrap

    The development of recycling process of defective (U,Gd)O2 scrap is one of the important subject in this project. Among the several burnable absorbers, Gd has a very large neutron absorption cross-section. Therefore, gadolinia bearing UO2 fuel, (U,Gd)O2, has been widely used as a burnable absorber in light water reactors. During the pellet fabrication process, fairly amount of defective (U,Gd)O2 pellets are produced and it is necessary to recycle the scraps. Generally, the defective scraps are powdered through the oxidation in air in the temperature range of 450 to 550 deg C and then mixed with co-milled powder, and further processed to fabricate (U,Gd)O2 pellets. In addition, the sintered pellet properties are closely depend on the powder property of oxidized M3O8 powder. Therefore, the careful investigate of oxidation kinetics and related powder property of (U,Gd)O2 is very important. The oxidation behavior of UO2-6wt% Gd2O3 and UO2-12wt% Gd2O3 has been studied in the temperature range from 350 to 700 deg C using TGA and XRD techniques in air. UO2 was necessarily oxidized to U3O8 regardless of oxidation temperature and its weight gain was 4wt%. However, (U,Gd)O2 exhibit a different oxidation behavior ; The final phase and saturated weight gain depends on oxidation temperature. The saturated weight gain increases with oxidation temperature up to 500deg C and thereafter decreases with temperature. In addition, the amount of weight gain obtained at 500 deg C was smaller in UO2-12wt% Gd2O3 than in UO2-6wt% Gd2O3 and the final phase at the saturated weight gain was M3O8 in UO2-6wt% Gd2O3 but the mixture of M4O9 and M3O8 in UO2-12wt% Gd2O3. It is supposed that Gd substitution for U decreases the equilibrium O/M ratio and thereby enhance the stability of M4O9 type cubic phase

  4. Design of absorber assemblies with intentional pellet-cladding mechanical interaction

    A number of improvements in absorber assembly performance characteristics can be achieved through implementation of absorber cladding mechanical interaction (ACMI). Benefits include lower operating temperatures, less potential for material relocation, longer lifetime, and increased reactivity worth. Analyses indicate that substantial cladding strains may be attainable without significant risk of breach. However, actual in-reactor testing of ACMI in absorber elements will be required before design criteria can be revised to accept ACMI

  5. Pellet injectors for JET

    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.)

  6. Wood pellet seminar

    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

  7. Burnable neutron absorbers

    This patent deals with the fabrication of pellets for neutron absorber rods. Such a pellet includes a matrix of a refractory material which may be aluminum or zirconium oxide, and a burnable poison distributed throughout the matrix. The neutron absorber material may consist of one or more elements or compounds of the metals boron, gadolinium, samarium, cadmium, europium, hafnium, dysprosium and indium. The method of fabricating pellets of these materials outlined in this patent is designed to produce pores or voids in the pellets that can be used to take up the expansion of the burnable poison and to absorb the helium gas generated. In the practice of this invention a slurry of Al2O3 is produced. A hard binder is added and the slurry and binder are spray dried. This powder is mixed with dry B4C powder, forming a homogeneous mixture. This mixture is pressed into green tubes which are then sintered. During sintering the binder volatilizes leaving a ceramic with nearly spherical high-density regions of

  8. Injection of Deuterium Pellets

    Sørensen, H.; Andersen, P.; Andersen, S. A.; Andersen, Verner; Nielsen, Arne Nordskov; Sass, Bjarne Ove; Weisberg, Knud-Vilhelm

    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 velocit...

  9. Wood pellet research program

    Sohkansanj, S.; Bi, T. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering

    2006-07-01

    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.

  10. Wood pellet research program

    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

  11. Standard specification for nuclear-grade aluminum oxide pellets

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification applies to pellets of aluminum oxide that may be ultimately used in a reactor core, for example, as filler or spacers within fuel, burnable poison, or control rods. In order to distinguish between the subject pellets and “burnable poison” pellets, it is established that the subject pellets are not intended to be used as neutron-absorbing material. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

  12. Tritium pellet injector results

    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 3He 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

  13. Shock implosion of a small homogeneous pellet

    A small spherical, or cylindrical, pellet is imploded by an intensive, evenly distributed, short energy pulse. At the surface of the pellet the matter ionizes, its temperature and pressure rapidly rise, and the ablated plasma, by reaction, implodes the inner nucleus of the pellet. The involved structure of the energy absorbing zone is idealized and a sharp deflagration front is considered. With an almost square energy pulse, slightly dropping with time, the solution of the mass, momentum, and energy conservation equations of the compressed matter, is self-similar. The differential equation of the nondimensional position of the deflagration front, its integral, and the magnitude and shape of the outside energy pulse are derived. The process of ablation is shown to depend solely on the nondimensional velocity of the gas just ahead of the deflagration front, minus the speed of sound, or the ratio of the gas densities across the deflagration front

  14. Shock implosion of a small homogeneous pellet

    Fujimoto, Y.; Mishkin, E.A.; Alejaldre, C.

    1985-10-01

    A small spherical, or cylindrical, pellet is imploded by an intensive, evenly distributed, short energy pulse. At the surface of the pellet the matter ionizes, its temperature and pressure rapidly rise, and the ablated plasma, by reaction, implodes the inner nucleus of the pellet. The involved structure of the energy absorbing zone is idealized and a sharp deflagration front is considered. With an almost square energy pulse, slightly dropping with time, the solution of the mass, momentum, and energy conservation equations of the compressed matter, is self-similar. The differential equation of the nondimensional position of the deflagration front, its integral, and the magnitude and shape of the outside energy pulse are derived. The process of ablation is shown to depend solely on the nondimensional velocity of the gas just ahead of the deflagration front, minus the speed of sound, or the ratio of the gas densities across the deflagration front.

  15. High speed pellet development

    Advanced pneumatic propulsion systems have been developed using two stage and arc heater guns. For pellet preparation a freezing cell for condensing the d2-gas is incorporated into the gun barrel. Results on the optimization of condensation parameters to find the mechanical limits of deuterium ice and of accelerations tests using a 2-stage gun with plastic as well as d2-pellets are discussed. It appears that two stage gun systems can provide a rather constant acceleration even in their low pressure regime suitable for pellet injection. The peak acceleration tolerable for d2-pellets, however turned out to be less than 5.106 ms-2 and a serious erosion effect of the pellet makes the use of long gun barrel rather problematic. At present it is concluded that only the sabot technique can overcome the stress and erosion effect limitations

  16. Pellet plant energy simulator

    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

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

    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....

  18. Mobile Biomass Pelletizing System

    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.

  19. Detonation drive pellet injector

    Detonation drive pellet injector has been developed and tested. By this method the free piston is not necessary because the pellet accelerated the high pressure shock directly. In the experiment, the Teflon pellet (5 mm dia., 5 mm length) was accelerated by hydrogen, oxygen and dilution gas mixtured detonation. When the gas pressure was only 500 kPa and the mixture rates of hydrogen, oxygen and helium were 3:6:1 or 3:6:0, the Teflon pellet speed was up to 747 m/s. Typical experimental results over 300 kPa of the initial gas pressure range are 78--92% of the one-dimensional calculational values. It showed that the pellet could be accelerated by a relative low pressure gas. When the helium dilution rate is larger than 20%, it was often found the strong detonation of which speed is more than the Chapman-Jouguet speed. Then the pellet speed above 1,100 m/s was obtained

  20. Pelletizing properties of torrefied spruce

    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 particles. The present study focused on the pelletizing properties of spruce torrefied at 250, 275 and 300 °C. The changes in composition were characterized by infrared spectroscopy and chemical analysis. The pelletizing properties were determined using a single pellet press and pellet stability was determined by compression testing. The bonding mechanism in the pellets was studied by fracture surface analysis using scanning electron microscopy. The composition of the wood changed drastically under torrefaction, 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 analysis revealed a cohesive failure mechanism due to strong inter-particle bonding in spruce pellets as a resulting from a plastic flow of the amorphous wood polymers, forming solid polymer bridges between adjacent particles. Fracture surfaces of pellets made from torrefied spruce possessed gaps and voids between adjacent particles due to a spring back effect after pelletization. They showed no signs of inter-particle polymer bridges indicating that bonding is likely limited to Van der Waals forces and mechanical fiber interlocking. -- Highlights: ► Thermal degradation of wood polymers increased with torrefaction temperature. ► Utilization of torrefied wood increased the friction in the press channel of a pellet mill. ► Pellets compression stability decreased with increasing

  1. Modeling pellet impact drilling process

    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.

  2. Pelletizing properties of torrefied spruce

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

    2011-01-01

    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...... analysis revealed a cohesive failure mechanism due to strong inter-particle bonding in spruce pellets as a resulting from a plastic flow of the amorphous wood polymers, forming solid polymer bridges between adjacent particles. Fracture surfaces of pellets made from torrefied spruce possessed gaps and voids...

  3. Absorber pin development in Europe

    The neutron absorbing material chosen for the absorber elements of the European fast reactor (EFR) is boron carbide. Various pin designs are studied in Europe: (1) vented helium-bonded pins chosen for prototype fast reactor (PFR) control rods, (2) vented sodium-bonded pins chosen for the Phenix and Superphenix control rods, (3) vented shrouded sodium-bonded pins chosen for future loads of Superphenix control ros. There are three aspects to the research and development program to evaluate absorber pin performance: (1) experimental irradiation program dealing with basic studies and validation design experiments, (2) modeling of B4C physical properties, descriptive laws, and code development, (3) design optimization and innovative studies (various B4C enrichments and pellet densities, new absorber materials). The irradiation program is being performed in Phenix and PFR using either control rods or static rigs

  4. Fundamentals of Biomass pellet production

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

    2005-01-01

    Gasification Group at MEK-DTU has been installed for experiments with different types of wood, straw, waste materials and additives such as adhesives and inorganic compounds. A series of pelletizing tests has been performed using a ring die with a compression ratio of 6.5. Pine shavings and beech wood dust has...... been tested individually and combined. Pine dust is relatively easy to pelletize while beech dust is almost impossible to pelletize with the present pellet mill conditions. Additionally, the inorganic part of the beech wood was rich in corrosive alkali chloride salts. With the die used it was possible...... corrosiveness and the sintering ability of the ash residues. It had earlier been observed that straw could be pelletized, but that the pellet quality in general did not appear to be very high. Similar results have been obtained in the present study. The pellets were not as durable as the pine/beech pellets...

  5. Owl Pellet Paleontology

    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,…

  6. Nuclear fuel pellet collating system

    This patent describes a system for collating nuclear fuel pellets. The system consists of: (a) a pellet collating line including serially-arranged pellet input, work and output stations; (b) a plurality of mobile carts, some supporting pellet supply trays and others supporting pellet storage trays, the trays adapted to support pellets in multiple rows thereof, the pellets on a given one tray being of the same enrichment with enrichments of pellets on some trays behind different from on other trays; (c) a tray positioning station located adjacent to the pellet collating line and defining positions in which are lodged the mobile carts; (d) tray transfer robot located between the pellet collating line and the try positioning station, the robot being operable to transfer supply and storage trays one at a time between the respective carts at the tray positioning station and respective input and output stations; (e) an input sweep head disposed adjacent the input station and being operable for sweeping pellets resting in multiple rows on a given one of the supply trays at the input station from the supply tray onto the work station; (f) a gripping and measuring head disposed adjacent the work station and being operable for measuring a desired length of pellets in the multiple rows thereof on the work station and then separating the measured desired length of pellets from the remaining pellets, if there be any; (g) an output sweep head disposed adjacent to the output station and operable for sweeping the measured lengths of pellets from the work station onto a given one of the storage trays at the output station; (h) one the input sweep head, the gripping and measuring head and the output sweep head being operable for sweeping the remaining pellets, if any, in the multiple rows thereof from the work station back onto the given one of the supply trays at the input station

  7. PELLETIZATION TECHNIQUES: A LITERATURE REVIEW

    Punia Supriya; Bala Rajni; Rana A. C.

    2012-01-01

    In present times, the pelletization technologies are gaining much attention as they represent an efficient pathway for manufacture of oral drug delivery systems. This is due to the reason that pellets offer many therapeutic, technological as well as biopharmaceutical advantages over the conventional oral dosage forms. Pelletization technique enables the formation of spherical beads or pellets with a mean diameter usually ranging from 0.5-2.0 mm which can be eventually coated for preparation o...

  8. Pneumatic pellet injector for JET

    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.)

  9. Pellet imaging techniques on ASDEX

    As part of a USDOE/ASDEX collaboration, a detailed examination of pellet ablation in ASDEX with a variety of diagnostics has allowed a better understanding of a number of features of hydrogen ice pellet ablation in a plasma. In particular, fast gated photos with an intensified Xybion CCD video camera allow in-situ velocity measurements of the pellet as it penetrates the plasma. With time resolution of typically 100 nanoseconds and exposures every 50 microseconds, the evolution of each pellet in a multi-pellet ASDEX tokamak plasma discharge can be followed. When the pellet cloud track has striations, the light intensity profile through the cloud is hollow (dark near the pellet), whereas at the beginning or near the end of the pellet trajectory the track is typically smooth (without striations) and has a gaussian-peaked light emission profile. New, single pellet Stark broadened DαDβ, and Dγ spectra, obtained with a tangentially viewing scanning mirror/spectrometer with Reticon array readout, are consistent with cloud densities of 2 x 1017cm-3 or higher in the regions of strongest light emission. A spatially resolved array of Dα detectors shows that the light variations during the pellet ablation are not caused solely by a modulation of the incoming energy flux as the pellet crosses rational q-surfaces, but instead are a result of a dynamic, non-stationary, ablation process. 20 refs., 4 figs

  10. Heterogeneous neutron absorbers development

    The use of solid burnable absorber materials in power light water reactors has increased in the last years, specially due to improvements attained in costs of generated electricity. The present work summarizes the basic studies made on an alumina-gadolinia system, where alumina is the inert matrix and gadolinia acts as burnable poison, and describes the fabrication method of pellets with that material. High density compacts were obtained in the range of concentrations used by cold pressing and sintering at 1600 deg C in inert (Ar) atmosphere. Finally, the results of the irradiation experiences made at RA-6 reactor, located at the Bariloche Atomic Center, are given where variations on negative reactivity caused by introduction of burnable poison rods were measured. The results obtained from these experiences are in good agreement with those coming from calculation codes. (Author)

  11. Method of manufacturing nuclear fuel pellet

    Purpose: To effectively absorb the swelling at the central portion of a pellet, as well as obtain a sufficient creep velocity and reduce the release of gaseous fission products in fuel pellets for use in BWR type reactors. Method: A pellet is divided into a central region and outer peripheral region. The crystal grain size and the porosity in the central region are made greater than those in the outer peripheral region. In the central region, the O/U ratio for the UO2 powder is set to 2.10 - 2.30, material for increasing crystal grain size (TiO2, Nb2O5, Cr2O3, etc.) is mixed as additives and the specific surface area is made to 3 - 8 g/cm3. Further, in the outer peripheral region, O/U ratio for the UO2 powder is set to 2.00 - 2.100, and material for increasing sintering density (Al(OH)3, Al, etc.) is mixed as additives and the specific surface area is set to 3 g/cm3. Thus, the increase in the inner pressure and the elevation of temperature for the fuel can in the fuel rod can effectively be suppressed to prevent stress corrosion cracking in the fuel can. (Ikeda, J.)

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

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

    2016-01-01

    (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......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.......% was found to be optimal for the six biomass feedstocks. A friction increase was seen when the die temperature increased from room temperature to 60-90 degrees C for most biomass types, and then a friction decrease when the die temperature increased further. The results obtained in the bench...

  13. An investigation into the behaviour of air rifle pellets in ballistic gel and their interaction with bone.

    Wightman, G; Beard, J; Allison, R

    2010-07-15

    Although air weapons are considerably lower in power than other firearms, there is increasing concern that serious injuries can result from their misuse. The present study was therefore carried out to improve understanding of the terminal ballistic behaviour of air rifle pellets. Pellets were fired into ballistic gel under a variety of conditions. The pellets penetrated further than anticipated from their low cross-sectional density, and Bloom number was not necessarily a good guide to gel behaviour. Pellet penetration into the gel decreased with increasing gel concentration, and appeared to be linear at higher concentrations. Pointed pellets penetrated up to 50% further than rounded pellets. Power and range affect penetration, but other factors are also important, and power alone is not a simple guide to potential penetration. Test firings were also carried out firing pellets into ballistic gel that contained sections of animal bone. Computed tomography (CT) and visual observation were employed to record the interactions. CT scanning showed potential as a tool for examining pellet damage. The bone appeared to be undamaged, but the pellets were severely deformed on impact. If the pellet strikes the bone at an angle, less energy is absorbed by the impact and the pellet fragments may ricochet and cause further damage in the gel. A tentative model is proposed for estimating the energy absorbed by the impact. PMID:20413234

  14. Degradation of copepod fecal pellets

    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 (<0.2, <2, <20, <100, <200 mu m) and total (unfractionated). We determined fecal 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...

  15. Sintering behavior of ceria pellets

    Abd El-Halim, A.S.; Abdelmonem, N.M.; Abd El-Hamid, G.; Afify, N.A.

    1989-02-01

    The sintering behaviour of ceria pellets was studied to produce dense, sound and crack-free pellets. Ceria is prepared by the precipitation of ammonium cerous carbonate (ACeC). The precipitate of ACeC is dried and then calcined to produce ceria (CeO/sub 2/) powder. The ceria powder is used to fabricate pellets which are sintered at 1200...1500/sup 0/C. It was found that higher density (more than 85% of the theoretical), sound and crack-free ceria pellets can be obtained via calcination of ACeC powders at 600/sup 0/C for 2 h, pressing the obtained ceria powders into pellets at 550 N/mm/sup 2/, and then sintering these pellets at 1500/sup 0/C for 3 h in air.

  16. Pellets direct from the forest

    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

  17. PELLETIZATION TECHNIQUES: A LITERATURE REVIEW

    Punia Supriya

    2012-03-01

    Full Text Available In present times, the pelletization technologies are gaining much attention as they represent an efficient pathway for manufacture of oral drug delivery systems. This is due to the reason that pellets offer many therapeutic, technological as well as biopharmaceutical advantages over the conventional oral dosage forms. Pelletization technique enables the formation of spherical beads or pellets with a mean diameter usually ranging from 0.5-2.0 mm which can be eventually coated for preparation of modified release dosage forms. Pelletization leads to an improvement in flowability, appearance and mixing properties thus avoiding generation of excessive dust and reducing segregation, and, generally, eliminating undesirable properties and improving the physical and chemical properties of fine powders. Pellets are produced by various techniques, such as, extrusion/ spheronization, layering, cryopelletization, freeze pelletization, spray congealing, spray drying and compression. Amongst various techniques, Extrusion/Spheronization technique is the most widely utilized technique due to its high efficiency and simple and fast processing. The aim of this paper is to review some general aspects about pellets and pelletization and some common techniques being utilized in the pharmaceutical industry.

  18. Pellet injector development at ORNL

    Plasma fueling systems for magnetic confinement experiments are under development at Oak Ridge National Laboratory (ORNL). ORNL has recently provided a four-shot tritium pellet injector with up to 4-mm-diam capability for the Tokamak Fusion Test Reactor (TFTR). This injector, which is based on the in situ condensation technique for pellet formation, features three single-stage gas guns that have been qualified in deuterium at up to 1.7 km/s and a two-stage light gas gun driver that has been operated at 2.8-km/s pellet speeds for deep penetration in the high-temperature TFTR supershot regime. Performance improvements to the centrifugal pellet injector for the Tore Supra tokamak are being made by modifying the storage-type pellet feed system, which has been redesigned to improve the reliability of delivery of pellets and to extend operation to longer pulse durations (up to 400 pellets). Two-stage light gas guns and electron-beam (e-beam) rocket accelerators for speeds in the range from 2 to 10 km/s are also under development. A repeating, two-stage light gas gun that has been developed can accelerate low-density plastic pellets at a 1-Hz repetition rate to speeds of 3 km/s. In a collaboration with ENEA-Frascati, a test facility has been prepared to study repetitive operation of a two-stage gas gun driver equipped with an extrusion-type deuterium pellet source. Extensive testing of the e-beam accelerator has demonstrated a parametric dependence of propellant burn velocity and pellet speed, in accordance with a model derived from the neutral gas shielding theory for pellet ablation in a magnetized plasma

  19. ORNL centrifuge pellet fueling system

    A centrifuge pellet injecter designed and built at Oak Ridge National Laboratory (ORNL) is in operation on Tore Supra. This injector has the capability of injecting up to 100 pellets at speeds up to 800 M/s. The solid deuterium pellets can be formed with a variable mass from 3 to 10 torr-L and are fired at a rate of up to 10 pellets per second. The experimental program that is under way combines repetitive pellet fueling with the ergodic divertor and pump limiters to establish and understand long-pulse plasmas in which the pellet fuel source is in balance with the particle exhaust. With lower hybrid current drive, pulse lengths of up to 2 min might be achieved. To prepare for these extended pulse lengths, the pellet source on the centrifuge will be extended to provide a 300- to 500-pellet capability. A similar system extended to steady-state pellet fabrication technology and designed for a radiation and tritium environment would be a candidate for a fueling system for the International Thermonuclear Experimental Reactor (ITER). Analysis of pellet-fueled ITER discharges using the WHIST code shows the potential for controlling the radial fuel deposition point to achieve the desired core density while maintaining the edge density and temperatures so as to minimize the diverter plate erosion. A centrifuge fueling system would have the capability of taking the D-T exhaust directly from the cryopumping systems, recondensing and purifying the fuel, and injecting the reconstituted pellets into the plasma, thereby minimizing the tritium inventory

  20. Owl Pellets and Crisis Management.

    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.…

  1. Novel method to assess gastric emptying in humans: the Pellet Gastric Emptying Test

    Choe, S. Y.; Neudeck, B. L.; Welage, L. S.; Amidon, G. E.; Barnett, J. L.; Amidon, G. L.

    2001-01-01

    To further validate the Pellet Gastric Emptying Test (PGET) as a marker of gastric emptying, a randomized, four-way crossover study was conducted with 12 healthy subjects. The study consisted of oral co-administration of enteric coated caffeine (CAFF) and acetaminophen (APAP) pellets in four treatment phases: Same Size (100 kcal), Fasted, Small Liquid Meal (100 kcal), and Standard Meal (847 kcal). The time of first appearance of measurable drug marker in plasma, t(initial), was taken as the emptying time for the markers. Co-administration of same size enteric coated pellets of CAFF and APAP (0.7 mm in diameter) revealed no statistically significant differences in t(initial) values indicating that emptying was dependent only on size and not on chemical make-up of the pellets. Co-administration of different size pellets indicated that the smaller 0.7-mm diameter (CAFF) pellets were emptied and absorbed significantly earlier than the larger 3.6-mm diameter (APAP) pellets with both the Small Liquid Meal (by 35 min) and the Standard Meal (by 33 min) (P<0.05). The differences in emptying of the pellets were not significant in the Fasted Phase. The results suggest that the pellet gastric emptying test could prove useful in monitoring changes in transit times in the fasted and fed states and their impact on drug absorption.

  2. Manufacture, delivery and marketing of wood pellets

    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

  3. Tritium pellet injector for TFTR

    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

  4. Tritium pellet injector for TFTR

    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. A 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 pellets. 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

  5. Moving behavior of pellets in a pellet shaft furnace

    梁儒全; 赫冀成

    2008-01-01

    The downward moving behavior of pellets in a 8 m2 pellet shaft furnace with an internal vertical air channel and a drying bed was studied by means of a visualized model(1-15) and a top model(1-1).The visualized model experiment shows that the downward movement of pellets can be regarded as plug flow approximately inside the furnace except for the lower region of cooling zone due to the influence of the drained hopper.The top model experiment reveals that the pellet sizes increase along the moving direction because of the percolation phenomenon,which results in a decrease of the resistance coefficient and an increase of the gas flow rate from the furnace wall toward the furnace center.

  6. Pellet injection and toroidal confinement

    The proceedings of a technical committee meeting on pellet injection and toroidal confinement, held in Gut Ising, Federal Republic of Germany, 24-26 October, 1988, are given in this report. Most of the major fusion experiments are using pellet injectors; these were reported at this meeting. Studies of confinement, which is favorably affected, impurity transport, radiative energy losses, and affects on the ion temperature gradient instability were given. Studies of pellet ablation and effects on plasma profiles were presented. Finally, several papers described present and proposed injection guns. Refs, figs and tabs

  7. Method of fabricating nuclear fuel pellets

    Purpose: To use uranium tetraoxide as a pore forming agent thereby to produce UO2 nuclear fuel pellets having stable pores almost not liable to shrink by heat or radiation during the operation of the reactor. Method: UO2 powder, alone or added with a Gd2O3 powder up to 6% of the former as a neutron absorber, is mixed with 5 to 15% based on mixed powder of UO4, nH2O powder of 10 to 325 meshes. Thus obtained mixed powder is pressed, formed, and sintered. In the sintering process, UO4.nH2O gradually loses its crystal water, and is converted into UO2, it shrinks and pores remain in the sintered body. (Kamimura, M.)

  8. Pelletizing of sulfide molybdenite concentrates

    Palant, A. A.

    2007-04-01

    The results of a pelletizing investigation using various binding components (water, syrup, sulfite-alcohol distillery grains, and bentonite) of the flotation sulfide molybdenite concentrate (˜84% MoS2) from the Mongolian deposit are discussed. The use of syrup provides rather high-strength pellets (>3 N/pellet or >300 g/pellet) of the required size (2 3 mm) for the consumption of 1 kg binder per 100 kg concentrate. The main advantage of the use of syrup instead of bentonite is that the molybdenum cinder produced by oxidizing roasting of raw ore materials is not impoverished due to complete burning out of the syrup. This fact exerts a positive effect on the subsequent hydrometallurgical process, decreasing molybdenum losses related to dump cakes.

  9. Handling of Deuterium Pellets for Plasma Refuelling

    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...

  10. Binders for pellets from biomass

    Bartoš, Pavel

    2013-01-01

    Pellets from biomass represent an appropriate form of biofuel for combustion. They are characterized by good fuel parameters, they enable efficient storage, transport and handling, and automatic fuel supply to the combustion chamber. Pellet production is quite a complicated and energy-consuming process. During the production it is necessary to ensure that the amount of input energy was the same or even smaller than the energy obtained. To streamline the production and improve thermo-mechanica...

  11. Centrifuge pellet injector for JET

    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.)

  12. Physics of inertial confinement pellets

    An overview of inertial confinement fusion pellet physics is given. A discussion is presented of current estimated ICF driver requirements and a couple of pellet examples. The physics of driver/plasma coupling for two drivers which are being considered, namely a laser driver and a heavy ion accelerator driver, is described. Progress towards inertial confinement fusion that has been made using laser drivers in target experiments to date is discussed

  13. Solid deuterium centrifuge pellet injector

    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 1500 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

  14. 46 CFR 148.04-21 - Coconut meal pellets (also known as copra pellets).

    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)...

  15. Intelligent Automated Nuclear Fuel Pellet Inspection System

    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

  16. Pelletization Techniques for Oral Drug Delivery

    Jagan Mohan Kandukuri

    2009-07-01

    Full Text Available Multiparticulates are discrete particles that make up a multiple unit system. Although 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. The manufacturing techniques include layering, cryopelletization, freeze pelletization, extrusion spheronization and hot melt extrusion have been discussed. Characterization of pellets is discussed with reference to the particle size distribution, surface area, porosity, density, hardness, friability and tensile strength of pellets.

  17. LIBS Detection of Heavy Metal Elements in Liquid Solutions by Using Wood Pellet as Sample Matrix

    Laser-induced breakdown spectroscopy (LIBS) has been applied to the analysis of heavy metals in liquid samples. A new approach was presented to lower the limit of detection (LOD) and minimize the sample matrix effects, in which dried wood pellets absorbed the given amounts of Cr standard solutions and then were baked because they have stronger and rapid absorption properties for liquid samples as well as simple elemental compositions. In this work, we have taken a typical heavy metal Cr element as an example, and investigated the spectral feasibility of Cr solutions and dried wood pellets before and after absorbing Cr solutions at the same experimental conditions. The results were demonstrated to successfully produce a superior analytical response for heavy metal elements by using wood pellet as sample matrix according to the obtained LOD of 0.07 ppm for Cr element in solutions

  18. Standard specification for nuclear-grade aluminum oxide-boron carbide composite pellets

    American Society for Testing and Materials. Philadelphia

    2005-01-01

    1.1 This specification applies to pellets composed of mixtures of aluminum oxide and boron carbide that may be ultimately used in a reactor core, for example, in neutron absorber rods. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

  19. Development of a pellet cutting and loading device for the JT-60 repetitive pellet injector

    In JT-60, a pellet injector that repetitively injects deuterium pellets is under development to supply fuel to high temperature plasmas and sustain high-density plasmas. The pellet injector generates cubic pellets and accelerates them with a straight-arm rotor by centrifugal force. In this acceleration method, it is important to supply pellets reliably and stably, to prevent pellet orbits from disordering and to stabilize the launching direction. To achieve higher performance of the injector, a pellet cutting and loading device that cuts a deuterium ice rod into cubic pellets and loads them to the pellet injector successively and stably has been developed. The pellet cutting and loading device can cut a deuterium ice rod produced at low temperature of -8 Pam3/s, cutting time of <3 ms, cutting frequency of 1-20 Hz and cutter stroke of 2.5 mm were confirmed in the device test. In the operation test after assembling this device to the centrifugal pellet injector, the operational performance of pellet injection frequency of ∼10 Hz, pellet speed of ∼690 m/s and pellet injection duration time of ∼3.5 s was achieved. Thus, the development of the pellet cutting and loading device contributed to the upgrade of the JT-60 pellet injector. (author)

  20. Pellet injection into ASDEX upgrade plasmas

    This work comprises results obtained using the new centrifuge injection system for the two first years of pellet injection experiments at Asdex Upgrade until the end of the 1995 experimental campaign. The main aim of the pellet injection investigation is to develop scenarios allowing for a more flexible plasma density control means of injection of cryogenic solid hydrogen pellets. Efforts have been made to develop scenarios allowing more flexible plasma density control by injecting cryogenic solid hydrogen pellets. While the injection of pellets during ohmic discharges was found to be most efficient and also improves the plasma performance, increasing the auxiliary heating power causes a detoriation of the pellet fuelling efficiency. A further strong reduction of the pellet fuelling efficiency by an additional process was observed for the more reactor-relevant conditions of shallow particle deposition during H-mode phases. With injection during type I ELMy H-mode phases, each pellet was found to trigger the release of an ELM and therefore cause particle losses mainly from the edge region. In the type I ELMy H-mode, only sufficient pellet penetration allowed noticeable, persistent particle deposition in the plasma by the pellets. Applying adequate pellet injection conditions and favourable scenarios using combined pellet/gas puff refuelling, significant density ramp-up to densities exceeding the empirical Greenwald limit by up to a factor of two was achieved even for strongly heated H-mode plasmas. (orig.)

  1. Method of producing ceramic fuel pellets

    Prior to the evaporation procedure the UO2-ceramic powder, possible to sinter, is mixed with epoxy resin pellets or UO2-gel-pellets and compacted at a pressure between 700 and 2800 kg/cm2. After sintering at 12000 up to 16500C the pellets show a uniform porosity. (RW)

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

    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.

  3. Method for fabricating ceramic nuclear fuel pellets

    Purpose: To fabricate ceramic nuclear fuel pellets with ease and efficiently capable of preventing deformation failures in cladding tubes due to thermal deformation of pellets. Method: Nuclear fuel pellets are arranged in one layer while incorporating grinding material in the inner wall of a cylindrical vessel and the end face of the nuclear fuel pellets are rounded to a predetermined shape by rotating the cylindrical vessel. Since the pellets do not form a saddle-like shape (expanded at both ends) upon thermal deformation the surface of the cladding tube less tends to form bamboo node-like ridges, thus to reduce the deformation failure of the cladding tube. (Aizawa, K.)

  4. Power from Pellets Technology and Applications

    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.

  5. IAEA technical committee meeting on pellet injection

    The IAEA Technical Committee Meeting on Pellet Injection, May 10-12, 1993, at the Japan Atomic Energy Research Institute, Naka, Ibaraki-ken, Japan, was held to review the latest results on pellet injection and its effects on plasma confinement. In particular, topics included in the meeting include (i) pellet ablation and particle fueling results, (ii) pellet injection effects on confinement, including improved confinement modes, edge effects, magnetohydrodynamic activity and impurity transport, and (iii) injector technology and diagnostics using pellets. About 30 experts attended and 23 papers were presented. Refs, figs and tabs

  6. Integration of a wood pellet burner and a Stirling engine to produce residential heat and power

    The integration a Stirling engine with a pellet burner is a promising alternative to produce heat and power for residential use. In this context, this study is focused on the experimental evaluation of the integration of a 20 kWth wood pellet burner and a 1 kWe Stirling engine. The thermal power not absorbed by the engine is used to produce hot water. The evaluation highlights the effects of pellet type, combustion chamber length and cycling operation on the Stirling engine temperatures and thermal power absorbed. The results show that the position of the Stirling engine is highly relevant in order to utilize as much as possible of the radiative heat from the burner. Within this study, only a 5 cm distance change between the Stirling engine and the pellet burner could result in an increase of almost 100 °C in the hot side of the engine. However, at a larger distance, the temperature of the hot side is almost unchanged suggesting dominating convective heat transfer from the hot flue gas. Ash accumulation decreases the temperature of the hot side of the engine after some cycles of operation when a commercial pellet burner is integrated. The temperature ratio, which is the relation between the minimum and maximum temperatures of the engine, decreases when using Ø8 mm wood pellets in comparison to Ø6 mm pellets due to higher measured temperatures on the hot side of the engine. Therefore, the amount of heat supplied to the engine is increased for Ø8 mm wood pellets. The effectiveness of the engine regenerator is increased at higher pressures. The relation between temperature of the hot side end and thermal power absorbed by the Stirling engine is nearly linear between 500 °C and 660 °C. Higher pressure inside the Stirling engine has a positive effect on the thermal power output. Both the chemical and thermal losses increase somewhat when integrating a Stirling engine in comparison to a stand-alone boiler for only heat production. The overall efficiency of

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

    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. PMID:26964334

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

    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)

  9. Application of burnable poisons integrated with fuel pellets in LWR

    The problem of using burnable poisons (gadolinium and erbium oxides) integrated with fuel pellets for suppression of the excess reactivity in the LWR reactor cores at fuel cycle begin when the fuel with maximum enrichment is loaded in the core is discussed. It is shown that application of the fuel elements with such pellets ensures sufficient burnup growth for fuel with increased enrichment, increase in the fuel cycle duration and decrease in neutron fluence on reactor vessel in the cases of optimized layouts of fresh and irradiated fuel assemblies in the reactor core. Basing on the analysis of studying into (U, Gd)O2 pellet heating and thermal conductivity under high burnups it is proved that the fuel with enrichment of 4.4 % of 235U may be used if the Gd2O3 content amounts to 2 %. Application of erbium absorber is recommended in uranium and plutonium fuel in inertial (nonfissible) matrix designed for burnups greater than 100 GeV · days/t

  10. Effect of ablatant composition on the ablation of a fuelling pellet

    The single species neutral-shielding model for the ablation of a hydrogenic pellet is extended by considering the ablatant as a mixture of four species: molecular and atomic hydrogen, protons and electrons. Compared with the results of the frozen flow, (i.e. the single species molecular hydrogen gas model), results of the analysis showed that the presence of dissociation and ionization effects caused a marked difference of the ablatant state. The attenuations of the incoming electron energy and energy flux, however, are very much similar irrespective of whether the ablated flow is in a frozen or an equilibrium state. The scaling law of the pellet ablation rate with respect to the plasma state of Te, ne and the pellet radius remains the same; the ablation rate is reduced by approximately 15%. To examine the possible existence of a spherical shell around the pellet where most of the incoming electron energy is absorbed, a comparison is made between the local electron collisional mean free path and the electron Larmor radius. A critical field at the ionization radius is evaluated. An effective spherical energy-absorbing region exists when the local field strength is below the critical value. For a plasma state of low Te and ne, (where the ablatant is hardly ionized), and for one near the thermonuclear condition (where a highly dense ablatant exists near the pellet), the effective energy absorption region is nearly spherical. In view of the variation of the plasma temperature and density as well as the pellet radius during the penetration of a pellet in a tokamak discharge, the existence of such an effective spherical energy absorption region still requires further exploration. (author)

  11. Microstructure and kinetics evolution in MgH2–TiO2 pellets after hydrogen cycling

    Highlights: • MgH2 was ball milled with TiO2 anatase phase and expanded graphite to prepare pellets. • Different pellets have been prepared at different compression load. • Pellets were repeatedly cycled under hydrogen pressure to simulate tank exercise and verify their stability. • The compression load highly affects the stability of the pellets to cycling. • Microstructural evolution of the particles due to cycling have been observed. - Abstract: The interest in Mg-based hydrides for solid state hydrogen storage is associated to their capability to reversibly absorb and desorb large amounts of hydrogen. In this work MgH2 powder with 5 wt.% TiO2 was ball milled for 10 h. The as-milled nanostructured powder was enriched with 5 wt.% of Expanded Natural Graphite (ENG) and then compacted in cylindrical pellets by cold pressing using different loads. Both the powder and the pellets were subjected to kinetic and thermodynamic tests using a Sievert’s type gas reaction controller, in order to study the microstructural and kinetic changes which took place during repeated H2 absorption and desorption cycles. The pellets exhibited good kinetic performance and durability, even if the pressure of compaction revealed to be an important parameter for their mechanical stability. Scanning Electron Microscopy observations of as-prepared and cycled pellets were carried out to investigate the evolution of their microstructure. In turn the phase composition before and after cycling was analyzed by X-ray diffraction

  12. Acoustic coherent perfect absorbers

    In this paper, we explore the possibility of achieving acoustic coherent perfect absorbers. Through numerical simulations in two dimensions, we demonstrate that the energy of coherent acoustic waves can be totally absorbed by a fluid absorber with specific complex mass density or bulk modulus. The robustness of such absorbing systems is investigated under small perturbations of the absorber parameters. We find that when the resonance order is the lowest and the size of the absorber is comparable to the wavelength in the background, the phenomenon of perfect absorption is most stable. When the wavelength inside both the background and the absorber is much larger than the size of the absorber, perfect absorption is possible when the mass density of the absorber approaches the negative value of the background mass density. Finally, we show that by using suitable dispersive acoustic metamaterials, broadband acoustic perfect absorption may be achieved. (papers)

  13. Pellet fuelling in Tore Supra long discharges

    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 minutes 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 2 comparable pellet fuelled and gas fuelled discharges has been done. In the 2 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 1019 m-3). (authors)

  14. Pellet injector development and experiments at ORNL

    The development of pellet injectors for plasma fueling of magnetic confinement fusion experiments has been under way at Oak Ridge National Laboratory (ORNL) for the past 15 years. Recently, ORNL provided a tritium-compatible four-shot pneumatic injector for the Tokamak Fusion Test Reactor (TFTR) based on the in situ condensation technique that features three single-stage gas guns and an advanced two-stage light gas gun driver. In another application, ORNL supplied the Tore Supra tokamak with a centrifuge pellet injector in 1989 for pellet fueling experiments that has achieved record numbers of injected pellets into a discharge. Work is progressing on an upgrade to that injector to extend the number of pellets to 400 and improve pellet repeatability. In a new application, the ORNL three barrel repeating pneumatic injector has been returned from JET and is being readied for installation on the DIII-D device for fueling and enhanced plasma performance experiments. In addition to these experimental applications, ORNL is developing advanced injector technologies, including high-velocity pellet injectors, tritium pellet injectors, and long-pulse feed systems. The two-stage light gas gun and electron-beam-driven rocket are the acceleration techniques under investigation for achieving high velocity. A tritium proof-of-principle (TPOP) experiment has demonstrated the feasibility of tritium pellet production and acceleration. A new tritium-compatible, extruder-based, repeating pneumatic injector is being fabricated to replace the pipe gun in the TPOP experiment and will explore issues related to the extrudability of tritium and acceleration of large tritium pellets. The tritium pellet formation experiments and development of long-pulse pellet feed systems are especially relevant to the International Tokamak Engineering Reactor (ITER)

  15. Pelletization Techniques for Oral Drug Delivery

    Jagan Mohan Kandukuri; Venkatesham Allenki; Chandra Mohan Eaga; Vasu Keshetty; Kiran Kumar Jannu

    2009-01-01

    Multiparticulates are discrete particles that make up a multiple unit system. Although 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 manufacturi...

  16. Pelletizing properties of torrefied wheat straw

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

    2013-01-01

    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....

  17. Capabilities of nitrogen admixed cryogenic deuterium pellets

    Sharov, Igor; Sergeev, Vladimir [SPU, Saint-Petersburg (Russian Federation); Lang, Peter; Ploeckl, Bernhard; Cavedon, Marco [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany); Kocsis, Gabor; Szepesi, Tamas [Wigner RCP RMI, Budapest (Hungary); Collaboration: ASDEX Upgrade Team

    2015-05-01

    Operation at high core density with high energy confinement - as foreseen in a future fusion reactor like DEMO - is being investigated at ASDEX Upgrade tokamak. The efficiency of pellet fuelling from the high-field side usually increases with increasing injection speed. Due to the fragile nature of the deuterium ice, however, the increment of pellet mass losses and subsequent pellet fragmentations take place when the speed is increased. Studies show, that admixing of a small amount of nitrogen (N{sub 2}) into D{sub 2} gas can be favorable for the mechanical stability of pellets. This might be helpful for deeper pellet penetration. Besides, seeding by N{sub 2} can enhance plasma performance due to both increasing the energy confinement time and reducing the divertor heat load in the envisaged ELMy H-mode plasma scenario. Fuelling efficiency of N{sub 2}-admixed solid D{sub 2} pellets and their nitrogen seeding capabilities were investigated. It was found that both the overall plasma density increase and the measured averaged pellet penetration depth were smaller in case of the admixed (1% mol. in the gas resulting in about 0.8% in the ice) pellet fuelling. Possibility of the N{sub 2}-seeding by admixed pellets was confirmed by CXRS measurements of N{sup 7+} content in plasma.

  18. Screw Extruder for Pellet Injection System

    Sharadkumar K. Chhantbar

    2014-05-01

    Full Text Available Solid hydrogenic pellets are used as fuel for fusion energy reactor. A technique for continuous production of solid hydrogen and its isotopes by a screw extruder is suggested for the production of an unlimited number of pellets. The idea was developed and patented by PELIN laboratories, Inc. (Canada. A Gifford McMahon cryocooler is used for the generation of solid hydrogenic fluid pellets. Requirements of the pellets is depends upon the energy to be produced by tokamak. This review paper focuses on the model for the screw extruder for solidification of hydrogen ice having high injection reliability.

  19. Micromachining for laser fusion pellet

    In laser nuclear fusion, the fusion reaction is induced by irradiating powerful laser beam on the pellets filled with fuel, and compressing and heating the fuel by implosion. At this time, in order to compress it up to high density, it is very important to compress as the spherical symmetry is maintained. The uniformity of the sphericity and wall thickness is required to be more than 98 %. Besides, in order to heighten the efficiency, it is necessary to limit the temperature of main fuel low, to ignite with hot sparks at the center, and to burn remaining fuel with the alpha particles which are generated by the nuclear fusion reaction there. For this purpose, various target structures have been proposed. The cryogenic target for ablative compression, the double shell target and the cannonball target are shown. In order to produce these targets, the development of the fuel spheres which have high uniformity and good sphericity in the required size, the development of the coating process with good surface finish which can do uniform coating at the rate of about 10 μm/h, the development of micromachining technology, the development of cryogenic technology and so on are necessary. Also the levitation of pellets by magnetic suspension method is explained. (K.I.)

  20. The ALICE absorbers

    Maximilien Brice

    2006-01-01

    Weighing more than 400 tonnes, the ALICE absorbers and the surrounding support structures have been installed and aligned with a precision of 1-2 mm, hardly an easy task but a very important one. The ALICE absorbers are made of three parts: the front absorber, a 35-tonne cone-shaped structure, and two small-angle absorbers, long straight cylinder sections weighing 18 and 40 tonnes. The three pieces lined up have a total length of about 17 m.

  1. Process optimization of DUPIC fuel pellet fabrication

    DUPIC pellets are remotely fabricated by using DUPIC powder prepared by the OREOX treatment of spent fuel pellets. DUPIC pellets were successfully fabricated using spent PWR fuel material with an average discharge burn-up of 27,300 MWd/tU. Sintered density, grain size and surface roughness of the DUPIC pellets were investigated on the basis of CANDU fuel criteria. In order to optimize the DUPIC pellet manufacturing processes, 3 series of experiments for the pre-qualification and 3 series for the qualification were performed. In these experiments, the sintered densities of the pellets ranged from 10.35 g/cm3(95.7 % of T.D.) to 10.43 g/cm3(96.4 % of T.D.) and the average grain size ranged from 14.6 to 14.9 μm. Based on these results, the optimum manufacturing processes of DUPIC pellets have been established. Then, under the control of the QA program developed with the assistance of AECL, 8 series of production runs have been performed to make DUPIC pellets in a batch size of 1 kg. The sintered densities of the fabricated pellets ranged from 10.26 g/cm3 to 10.43 g/cm3. The surface roughness of the ground pellets was less than Ra 0.8 μm by the dry grinding process. As the results of the production runs, DUPIC fuel pellets meeting the standard CANDU fuel specifications were successfully fabricated by the established processes. (author)

  2. Pellets - A fuel with a future

    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

  3. Injection of pellets into the TCA tokamak

    This thesis presents experimental results from the analysis of the ablation process of pellets injected into the TCA tokamak. The determination of scaling laws relating the pellet penetration to the pellet and plasma parameters preceding injection, were used to improve the understanding of the interaction of the pellet with the plasma since a) the pellet and plasma conditions preceding injection were varied over a large range, and b) the estimation of the penetration depth takes into account the influence of striations in the deposition profile. Over 400 pellets with a range of sizes and speeds were injected into a range of plasma parameters in order to create a database from which the scaling laws could be deduced. The ablation characteristics were principally measured with two CCD video cameras, which provided good spatial resolution, and two filtered photomultiplier tubes, which provided good temporal resolution of the light emitted from the pellet ablation cloud. In the text, the traditional methods of analysing these diagnostics are examined with special reference to the presumptions that a) the pellet velocity is constant in the plasma, and b) the light intensity determined from the ablation cloud is proportional to the ablation rate. After successive data reduction from the database, in order to separate the effects of varying different parameters, the main observations were that, a) the pellet penetration varies as the square root of the pellet velocity, b) the scaling laws for the other parameters strongly depend on whether the pellet has sufficient velocity to reach the q=1 rational magnetic surface in the tokamak. (author) 45 refs

  4. Manufacture of wood-pellets doubles. Biowatti Oy started a wood pellet plant in Turenki

    Wood pellets have many advantages compared to other fuels. It is longest processed biofuel with favorable energy content. It is simple to use, transport and store. Heating with wood pellets is cheaper than with light fuel oil, and approximately as cheap as utilization of heavy fuel oil, about 110 FIM/MWh. The taxable price of wood pellets is about 550 FIM/t. Stokers and American iron stoves are equally suitable for combustion of wood pellets. Chip fueled stokers are preferred in Finland, but they are also suitable for the combustion of wood pellets. Wood pellets is an environmentally friendly product, because it does not increase the CO2 load in the atmosphere, and its sulfur and soot emissions are relatively small. The wood pelletizing plant of Biowatti Oy in Turenki was started in an old sugar mill. The Turenki sugar mill was chosen because the technology of the closed sugar factory was suitable for production of wood pellets nearly as such, and required only by slight modifications. A press, designed for briquetting of sugar beat clippings makes the pellets. The Turenki mill will double the volume of wood pellet manufacture in Finland during the next few years. At the start the annual wood pellet production will be 20 000 tons, but the environmental permit allows the production to be increased to 70 000 tons. At first the mill uses planing machine chips as a raw material in the production. It is the most suitable raw material, because it is already dry (moisture content 8-10%), and all it needs is milling and pelletizing. Another possible raw material is sawdust, which moisture content is higher than with planing machine chips. Most of the wood pellets produced are exported e.g. to Sweden, Denmark and Middle Europe. In Sweden there are over 10 000 single-family houses using wood pellets. Biowatti's largest customer is a power plant located in Stockholm, which combusts annually about 200 000 tons of wood pellets

  5. Refractory Pellet for Hot Blast Stove

    Wang Jing; Peng Xigao

    2011-01-01

    1 Scope This standard specifies the term,definition,classification,specification,technical requirements,test methods,quality appraisal procedures,packing,marking,transportation,storage,and quality certificate of refractory pellet for hot blast stove.This standard is applicable to refractory pellet for hot blast stove.

  6. Remote nuclear green pellet processing system

    A method of fabricating fuel pellets includes apparatus for compacting, granulating, classifying, lubricating and pelletizing the materials is described. The components are arranged below one another, allowing gravity flow, but are offset relative to the preceding stage so that overhead access is provided without interference. (U.K.)

  7. Inspecting fuel pellets for nuclear reactor

    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.)

  8. Hydrogen Pellet-Rotating Plasma Interaction

    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...

  9. Pellet-plasma interactions in tokamaks

    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 experiment...

  10. Pellet production methods for fueling fusion devices

    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.)

  11. Hydrogen Pellet-Rotating Plasma Interaction

    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 with a...

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

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

    2013-01-01

    Combined torrefaction and pelletization is used to increase the fuel value of biomass by increasing its energy density and improving its handling and combustion properties. In the present study, a single-pellet press tool was used to screen for the effects of pellet die temperature, moisture...... 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...

  13. Technologies for obtaining large grain sintered pellets

    A way to increase fuel burn-up is to use a large grains fuel pellets structure. The paper presents a literature review related to the technologies and the methods for large grains sintered pellets manufacturing. A flowsheet for large grains sintered pellets obtaining by Nb2O5 dopant addition in UO2 sinterable powder, pressing and sintering in H2 atmosphere is showed. In the diagrams are presented the dependency of the main sintered pellets characteristics (pore radius distribution, pores volume, density, grains size) as function of the Nb2O5 dopants concentration, UO2 sinterable powder nature and sintering temperature. Other sintered pellets characteristics (electrical conductivity, Seebeck coefficient, high temperature molar heat capacity and thermomechanical properties) are commented. The beneficial effects resulted from theoretical and practical projects are presented. (author)

  14. Influence of pellet shapes on sheath strains

    In the quest to reduce cladding strain from power ramps and thereby reduce the incidence of fuel defects, various aspects of pellet geometry have been examined experimentally. In parallel, the ELESTRES code has been developed to calculate the expansion and the hourglassing of fuel pellets. This paper presents the predictions of ELESTRES for the influence of pellet shapes on the pellet expansion, and compares them to measurements from two irradiations involving a total of 23 fuel elements. The experiments covered various combinations of pellet lengths, diameters, central holes, chamfer and dishes. The linear heat ratings ranged from 40 to 70 kW/m, with burnups up to 200 MW.h/kgU. The experiments and the predictions show similar trends for strains. Moreover, the predicted strains are generally within the scatter of experimental data. It is concluded that the code is in general agreement with this data

  15. Pellet-plasma interactions in tokamaks

    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...... confinement time, offset by the accumulation of impurities at the plasma core is brought into focus. A possible remedy is suggested to diminish the effect of the impurities. Plausible arguments are presented to explain the apparent controversial observations on the propagation of a fast cooling front ahead of...

  16. nondestructive characterization of nuclear fuel pellets

    The structural properties of UO2 ceramic pellets used as fuel in water-cooled nuclear power reactors affect their physical behaviours during reactor operation. Density, porosity, grain size and elastic constants are cryptical par meters to obtain a good performance from the pellets. Controlling of these parameters and determining them before preparing the pellets as fuel elements have importance in the optimization of fuel production conditions as well as the increasing of reactor performance. Ultrasonic velocity and attenuation changing by elastic interaction of ultrasonic waves with matter have been used as a basic tool in the characterization of UO2 pellets and ZrO2 pellets which are their simulation. In addition to this, under-water ultrasonic C-scan, microfocus x-graph y and penetrant techniques have been applied in the detecting of the defects, like cracks and laminations

  17. Evaluation of the in pile performance of boron containing fuel pellets

    The world rare earth resource are heavily concentrated in certain area and if these natural resources are weaponized by a country, we may confront serious difficulty because rare earth element gadolinium(Gd) is used as burnable poison material in some nuclear power plants (NPP) in Korea. Gd is used as a neutron absorbing material in Gd2O3 form and mixed with UO2 When boron is used as burnable poison in nuclear fuel, in fuel pellets. The burnable poison mixed in the fuel pellets is called integral burnable absorber (BA) design which differentiates it from the old separate BA design. In the old separate BA design, boron(B) was used in borosilicate glass (PYREX) form and placed in guide tubes. With the development of the concern over the availability of rare earth material Gd, B is considered as a candidate material replacing Gd for the case when the rare earth material is weaponized. However the idea for new boron BA design is integral type because the integral type BA design has several benefits over the separate BA design, such as reduction of radioactive waste, more positions for BA location, etc. 10B absorbs a neutron and produces helium by the following reaction: 10B + n → 7Li + 4He The helium produced by the nuclear reaction may cause the increase of rod internal pressure and change the gap conductivity if the significant amount of helium gas is released to the gap between the pellet and the cladding. Thus, it is necessary to investigate the in-pile behaviors of B containing pellet. However, few experiment have been carried out so far on the behavior of in-pile produced helium in UO2 fuel pellets, especially for the cases boron compound is mixed with UO2 In this paper, we will evaluate the production and the release of helium depending on fuel. 10B concentration in the fuel

  18. Comparative properties of bamboo and rice straw pellets

    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 pellets (CRP) met the requirements of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified includin...

  19. Speed of the internal pellet target in CSRm

    2009-01-01

    Pellet target is one of the main candidate targets in CSRm (cooler storage ring’s main ring) for hadron physics studies. Pellet speed is an important physical parameter for the target. Larger pellet speed could shorten the interacting time interval between the pellet and the cyclotron beam, and thus results in a small temperature variation for the pellet. This could make the pellet facility work in a stable condition. A fluid dynamic simulation was carried out for the pellet speed, and it was found that the maximum speed for the target pellet may be restricted to about 100 m/s even if all working parameters were set to their optimal values.

  20. Effect of ablatant composition on the ablation of a fuelling pellet

    The single species neutral-shielding model for the ablation of a hydrogenic pellet is extended by considering the ablatant as a mixture of four species: molecular and atomic hydrogen, protons and electrons. Compared with the results of the frozen flow, (i.e. the single species molecular hydrogen gas model), results of the analysis showed that the presence of dissociation and ionization effects caused a marked difference of the ablatant state. The attenuations of the incoming electron energy and energy flux, however, are very much similar irrespective of whether the ablated flow is in a frozen or an equilibrium state. The scaling law of the pellet ablation rate with respect to the plasma state of Te, ne and the pellet radius remains the same; the ablation rate is reduced by approximately 15%. To examine the possible existence of a spherical shell around the pellet where most of the incoming electron energy is absorbed, acodmparison is made between the local electron collisional mean free path and the electron Larmor radius. A critical field at the ionization radius is evaluated. An effective spherical energyabsorbing region exists when the local field strength is below the critical value. For a plasma state of low Te and ne, (where the ablatant is hardly ionized), and for one near the thermonuclear condition (where a highly dense ablatant exists near the pellet), the effective energy absorption region is nearly spherical. 20 refs. (author)

  1. A model of pellet ablation with a multi-species ablatant

    The single species neutral - shielding model for the ablation of a hydrogenic pellet is extended by considering the ablatant as a mixture of four species: Molecular and atomic hydrogen, protons and electrons. Compared with the single-species-ablatant model, results of the analysis showed that the ablatant state differs considerably. The attenuation of the incoming electron energy and energy flux, however, are very much similar, irrespective of the ablatant composition. The scaling law of the pellet ablation rate with respect to the plasma state of Te, ne and the pellet radius, rp remains the same; the ablation rate is reduced approximately by 15%. At some combinations of Te, ne and rp, a weak shock can appear when the ablated flow downstream becomes sonic. A sufficient but not necessary condition for its occurrence is that the ablatant approaches either a state of complete dissociation, or complete ionization. To study the possible existence of an effective energy absorbing spherical region around the pellet, a comparison between the local ablated electron collisional mean free path and the electron Larmor radius in the cloud is made. A critical field, Bc is then defined and evalued at the ionization radius, ri. For plasma state of fusion interest and pellet radius beyond 0.15 mm, Bc is well above 10 Tesla. (orig.) With 3 tabs., 7 figs., 21 refs

  2. A centrifuge CO2 pellet cleaning system

    Foster, C. A.; Fisher, P. W.; Nelson, W. D.; Schechter, D. E.

    1995-01-01

    An advanced turbine/CO2 pellet accelerator is being evaluated as a depaint technology at Oak Ridge National Laboratory (ORNL). The program, sponsored by Warner Robins Air Logistics Center (ALC), Robins Air Force Base, Georgia, has developed a robot-compatible apparatus that efficiently accelerates pellets of dry ice with a high-speed rotating wheel. In comparison to the more conventional compressed air 'sandblast' pellet accelerators, the turbine system can achieve higher pellet speeds, has precise speed control, and is more than ten times as efficient. A preliminary study of the apparatus as a depaint technology has been undertaken. Depaint rates of military epoxy/urethane paint systems on 2024 and 7075 aluminum panels as a function of pellet speed and throughput have been measured. In addition, methods of enhancing the strip rate by combining infra-red heat lamps with pellet blasting and by combining the use of environmentally benign solvents with the pellet blasting have also been studied. The design and operation of the apparatus will be discussed along with data obtained from the depaint studies.

  3. Pellet injector research and development at ORNL

    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

  4. A Review of Pellets from Different Sources

    Teresa Miranda

    2015-03-01

    Full Text Available The rise in pellet consumption has resulted in a wider variety of materials for pellet manufacture. Thus, pellet industry has started looking for alternative products, such as wastes from agricultural activities, forestry and related industries, along with the combination thereof, obtaining a broad range of these products. In addition, the entry into force of EN ISO 17225 standard makes wood pellet market (among other types possible for industry and household purposes. Therefore, wastes that are suitable for biomass use have recently increased. In this study, the main characteristics of ten kinds of laboratory-made pellets from different raw materials were analyzed. Thus, we have focused on the most limiting factors of quality standards that determine the suitability for biomass market, depending on the kind of pellet. The results showed considerable differences among the analyzed pellets, exceeding the limits established by the standard in almost all cases, especially concerning ash content and N and S composition. The requirements of the studied standard, very demanding for certain factors, disable the entry of these densified wastes in greater added value markets.

  5. Pellets - the advance of refined bioenergy

    This conference paper discusses the role of pellets in the use of bioenergy in Sweden. Pellets (P) have many advantages: (1) P are dry and can be stored, (2) P create local jobs, (3) P burn without seriously polluting the environment, (4) P are made from domestic and renewable resources, (5) P have high energy density, (6) P fit well in an energy system adapted to nature, (6) P are an economical alternative, both on a small scale and on a large scale. Pellets are more laborious to use than oil or electricity and require about three times as much storage space as oil. The Swedish pellets manufacturers per 1997 are listed. Locally pellets are most conveniently transported as bulk cargo and delivered to a silo by means of pressurized air. Long-distance transport use train or ship. At present, pellets are most often used in large or medium-sized heat plants, but equipment exists for use from private houses and up to the size of MW. Pellets may become the most important alternative to the fossil fuels which along with electricity today are dominating the small scale market. 1 fig., 1 table

  6. Burnable neutron absorber element

    A burnable thermal neutron absorber element is described comprising: a zirconium alloy elongated tubular container having an inside diameter surface; hydrogen diffusion barrier means for limiting hydrogen diffusion from within the container into the zirconium alloy; a boron-containing burnable thermal neutron absorber material sealed within the zirconium alloy elongated container, the boron-containing burnable absorber material being in a particle form, the particles of absorber material being coated with a diffusion barrier material; zirconium hydride sealed within the zirconium alloy elongated container, the zirconium hydride being in a partially hydrided condition and having a H to Zr ratio on an atomic basis in the range of about 1.0 to about 1.8; the burnable thermal neutron absorber material and the zirconium hydride distributed along the length of the zirconium alloy elongated container; and the zirconium hydride acts as a neutron moderator thereby enhancing the neutron capture efficiency of the burnable thermal neutron absorber

  7. Burnable neutron absorber element

    Ferrari, H.M.

    1988-06-14

    A burnable thermal neutron absorber element is described comprising: a zirconium alloy elongated tubular container having an inside diameter surface; hydrogen diffusion barrier means for limiting hydrogen diffusion from within the container into the zirconium alloy; a boron-containing burnable thermal neutron absorber material sealed within the zirconium alloy elongated container, the boron-containing burnable absorber material being in a particle form, the particles of absorber material being coated with a diffusion barrier material; zirconium hydride sealed within the zirconium alloy elongated container, the zirconium hydride being in a partially hydrided condition and having a H to Zr ratio on an atomic basis in the range of about 1.0 to about 1.8; the burnable thermal neutron absorber material and the zirconium hydride distributed along the length of the zirconium alloy elongated container; and the zirconium hydride acts as a neutron moderator thereby enhancing the neutron capture efficiency of the burnable thermal neutron absorber.

  8. Methods for absorbing neutrons

    Guillen, Donna P.; Longhurst, Glen R.; Porter, Douglas L.; Parry, James R.

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

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

    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

  10. Repeating pneumatic pellet injector in JAERI

    A repeating pneumatic pellet injector has been developed and constructed at Japan Atomic Energy Research Institute. This injector can provide repetitive pellet injection to fuel tokamak plasmas for an extended period of time, aiming at the improvement of plasma performance. The pellets with nearly identical speed and mass can be repeatedly injected with a repetition rate of 2-3.3 Hz and a speed of up to 1.7 km/s by controlling the temperature of the cryogenic system, the piston speed and the pressure of the propellant gas. (author)

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

    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/cm2. 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)

  12. Pellet injection experiments on the TFR tokamak

    The essential results of the pellet injection experiments carried out on the TFR Tokamak from 1983 until the shut-down of the machine in June 1986, are summarized. Hydrogen and deuterium pellets, occasionally doped with neon, were injected into ohmically and also additionally NB and ECR heated plasmas. Direct observation of the pellet trajectories yields insight in the properties of the ablation clouds. Measurements of the bulk plasma show a rapid temperature evolution during and just after the ablation process. The electron density changes radially on a much longer time scale. Transport simulations in particular for multi-pellet injection leads to the conclusion that the transport coefficients for the density transport are not drastically modified during the density relaxation phase

  13. UO2 pellet and manufacturing method

    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 UO2 powder having a specific surface area of from 5 to 50m2/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 UO2 pellet is from 3 to 25ppm, in one of a production step, a molding step or a sintering step for UO2 powder. With such procedures, a UO2 pellet having a large crystal grain size can be prepared with good reproducibility. (T.M.)

  14. Comment on Li pellet Conditioning in TFTR

    Li pellet conditioning in TFTR results in a reduction of the edge electron density which allows increased neutral beam penetration, central heating, and fueling. Consequently the temperature profiles became more peaked with higher central Ti, Te, and neutron emission rates.

  15. DURABILITY AND BREAKAGE OF FEED PELLETS DURING REPEATED ELEVATOR HANDLING

    Pelleting of animal feeds is important for improved feeding efficiency and for convenience of handling. Pellet quality impacts the feeding benefits for the animals and pellet integrity during handling. To determine the effect of repeated handling on feed pellet breakage and durability, a 22.6-t (100...

  16. Effect of magnesia on the compressive strength of pellets

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

    2014-01-01

    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 re-sults 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 re-duction 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.

  17. The development of the pellets market and of pellets technologies in Austria

    The market for pellets in the residential sector in Austria is presently expanding rapidly. About 30 manufacturers of small-scale pellet furnaces are currently active. An overall number of 21,959 pellet central heating systems with an entire nominal boiler capacity of 404,742 kW have been installed in Austria until the end of 2003. In 2004 15 pellet producers produced 325,000 tons of pellets. For 2005 an increase of the domestic pellets production up to 520,000 tons is forecasted. For 2010 a production capacity of one million tons of pellets is possible. Depending on the oil price a surplus pellets production of 40,000 t to 90,000 tons is forecasted for 2005. In the second half of 2004 the price for pellets was 219 l/ton for small bags (single), 199 l/ton for small bags (on pallet), 167 l/ton for bulk ( 6,000 kg) incl. delivery. (author)

  18. Development of advanced LWR fuel pellet technology

    A UO2 pellet was designed to have a grain size of larger than 12 μm, and a new duplex design that UO2-Gd2O3 is in the core and UO2-Er2O3 in the periphery was proposed. A master mixing method was developed to make a uniform mixture of UO2 and additives. The open porosity of UO2 pellet was reduced by only mixing AUC-UO2 powder with ADU-UO2 or milled powder. Duplex compaction tools (die and punch) were designed and fabricated, and duplex compacting procedures were developed to fabricate the duplex BA pellet. In UO2 sintering, the relations between sintering variables (additive, sintering gas, sintering temperature) and pellet properties (density, grain size, pore size) were experimentally found. The UO2-U3O8 powder which is inherently not sinterable to high density could be sintered well with the aid of additives. U3O8 single crystals were added to UO2 powder, and homogeneous powder mixture was pressed and sintered in a reducing atmosphere. This technology leads to a large-grained pellet of 12-20 μm. In UO2-Gd2O3 sintering, the relations between sintering variables (additives, sintering gas) and pellet properties (density, grain size) were experimentally found. The developed technology of fabricating a large-grained UO2 pellet has been optimized in a lab scale. Pellet properties were investigated in the fields of (1) creep properties, (2) thermal properties, (3) O/M ratios and (4) unit cell lattice. (author)

  19. Penetrated Shotgun Pellets: A Case Report

    Kara, M Isa; Polat, Hidayet B.; Ay, Sinan

    2008-01-01

    Shotgun wounds can result in devastating functional and aesthetic consequences for patients. There is no consensus in terms of removing or retaining foreign bodies such as shotgun pellets. In this report a 54-year-old man who suffered from accidental shotgun wounds on the face approximately 26 years ago is presented. Although most of pellets were still present, there were no symptoms such as poisoning, fistula formation, recurrent infections, or secondary hemorrhage to date except feeling col...

  20. Incorporation of industrial wastes in wood pellets

    Ferreira, Eduardo Campos; Vilarinho, Cândida; De Castro, F.; Pinto, A.; Ferreira, Pedro Tiago; Teixeira, J. C. F.

    2009-01-01

    ABSTRACT: The present work evaluates the incorporation of industrial wastes (Refuse Derived Fuel-RDF) into biomass for pellet production. Its influence on parameters such as pellet production, combustion and gas emissions was studied for up to 10% of residues incorporation. This approach also deals with the diverting of industrial waste from landfills. The main objectives were: increasing the heat value of the final product, diverting industrial residues with energy potential from landfill an...

  1. Dissolution test for homogeneity of mixed oxide fuel pellets

    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

  2. Wood pellets. The cost-effective fuel

    The article is based on an interview with Juhani Hakkarainen of Vapo Oy. Wood pellets are used in Finland primarily to heat buildings such as schools and offices and in the home. They are equally suitable for use in larger installations such as district heating plants and power stations. According to him wood pellets are suitable for use in coal-fired units generating heat, power, and steam. Price-wise, wood pellets are a particularly competitive alternative for small coal-fired plants away from the coast. Price is not the only factor on their side, however. Wood pellets also offer a good environmental profile, as they burn cleanly and generate virtually no dust, an important plus in urban locations. The fact that pellets are a domestically produced fuel is an added benefit, as their price does not fluctuate in the same way that the prices of electricity, oil, coal, and natural gas do. The price of pellets is largely based on direct raw material and labour costs, which are much less subject to ups and downs

  3. Ultrasonic analysis of sintered alumina pellets

    Uranium dioxide pellets are used as fuel in Pressurized Water Reactors. These pellets require some degree of porosity to accommodate fission products generated during the burning of fuel. It is usual to utilize the Archimedes method to determine the sintered pellet porosity. For the determination of closed pores, samples of pellets need to be analyzed using micrography to calculate the distribution of the pores. The ultrasonic group of the Nuclear Engineering Institute (IEN) is developing a nondestructive characterization through ultrasonic technique in the frequency domain, this technique will permit to minimize the time for determination of porosity and increase the accuracy of measurement using only one technique, taking into account pores open and closed, and to be capable to analyze 100% of the pellets. Several studies have been conducted in order to validate this method. In this work, the frequency spectrum from alumina pellets were obtained by a 5MHz frequency transducer and by means of scanning electron microscope (SEM), it was possible to investigate the interior of the material and to associate its structure to the behavior of the ultrasonic wave. Each sintering temperature showed a characteristic ultrasonic signal that could be associated with the Alumina porosity. This result showed that this method is very sensitive to the pore distribution in the material because, even within the same temperature group, variations occurred according to distribution of pore sizes. (author)

  4. Advanced turbine/CO2 pellet accelerator

    An advanced turbine/CO2 pellet accelerator is being evaluated as a depaint technology at Oak Ridge National Laboratory. The program, sponsored by Warner Robins Air Logistics Center, Robins Air Force Base, Georgia, has developed a robot-compatible apparatus that efficiently accelerates pellets of dry ice with a high-speed rotating wheel. In comparison to the more conventional compressed air sandblast pellet accelerators, the turbine system can achieve higher pellet speeds, has precise speed control, and is more than ten times as efficient. A preliminary study of the apparatus as a depaint technology has been undertaken. Depaint rates of military epoxy/urethane paint systems on 2024 and 7075 aluminum panels as a function of pellet speed and throughput have been measured. In addition, methods of enhancing the strip rate by combining infra-red heat lamps with pellet blasting have also been studied. The design and operation of the apparatus will be discussed along with data obtained from the depaint studies. Applications include removal of epoxy-based points from aircraft and the cleaning of surfaces contaminated with toxic, hazardous, or radioactive substances. The lack of a secondary contaminated waste stream is of great benefit

  5. Tritium proof-of-principle pellet injector

    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 3He separator, which was an integral part of the gun assembly, was capable of lowering 3He 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

  6. Wood pellets. The cost-effective fuel

    Anon.

    2001-07-01

    The article is based on an interview with Juhani Hakkarainen of Vapo Oy. Wood pellets are used in Finland primarily to heat buildings such as schools and offices and in the home. They are equally suitable for use in larger installations such as district heating plants and power stations. According to him wood pellets are suitable for use in coal-fired units generating heat, power, and steam. Price-wise, wood pellets are a particularly competitive alternative for small coal-fired plants away from the coast. Price is not the only factor on their side, however. Wood pellets also offer a good environmental profile, as they burn cleanly and generate virtually no dust, an important plus in urban locations. The fact that pellets are a domestically produced fuel is an added benefit, as their price does not fluctuate in the same way that the prices of electricity, oil, coal, and natural gas do. The price of pellets is largely based on direct raw material and labour costs, which are much less subject to ups and downs.

  7. Wood pellets offer a competitive energy option in Sweden

    The market for wood pellets in Sweden grew rapidly during the 1990s and production now stands at around 550,000 tonnes/year. More efficient combustion technology, pellet transportation, pellet storage and pellet delivery have also been developed. The pellets, which are produced by some 25 plants, are used in family houses, large-scale district heating plants, and combined heat and power (CHP) plants. Most of the pellets are made from biomass resources such as forest residues and sawdust and shavings from wood mills. Pellet production, the energy content of saw mill by-products, the current market and its potential for future expansion, the way in which the pellets are used in different combustion systems, the theoretical market potential for wood pellet heating installations in small houses and the Swedish P-certificate system for the certification of pellet stoves and burners are described

  8. Trapping of pellet cloud radiation in thermonuclear plasmas

    The experimental and theoretical data on radiation trapping in clouds of pellets injected into thermonuclear plasmas are presented. The theoretical modeling is performed in terms of equivalent Stark spectral line widths under condition of LTE (Sakha-Boltzman) in pellet cloud plasmas. It is shown that a domain of blackbody radiation could exist in hydrogen pellet clouds resulting in ''pellet disappearance'' effect which is absent in a case of impurity pellet clouds. Reasons for this difference are discussed. (author)

  9. Ciliates Expel Environmental Legionella-Laden Pellets To Stockpile Food

    Hojo, Fuhito; Sato, Daisuke; Matsuo, Junji; Miyake, Masaki; Nakamura, Shinji; Kunichika, Miyuki; Hayashi, Yasuhiro; Yoshida, Mitsutaka; Takahashi, Kaori; Takemura, Hiromu; Kamiya, Shigeru; Yamaguchi, Hiroyuki

    2012-01-01

    When Tetrahymena ciliates are cultured with Legionella pneumophila, the ciliates expel bacteria packaged in free spherical pellets. Why the ciliates expel these pellets remains unclear. Hence, we determined the optimal conditions for pellet expulsion and assessed whether pellet expulsion contributes to the maintenance of growth and the survival of ciliates. When incubated with environmental L. pneumophila, the ciliates expelled the pellets maximally at 2 days after infection. Heat-killed bact...

  10. Comparative properties of bamboo and rice straw pellets

    Xianmiao Liu

    2013-02-01

    Full Text Available 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 pellets (CRP met the requirements of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified including dimension, density, and strength. The inorganic ash (15.94 % and gross heat value (15375 J/g of rice straw pellets could not meet the requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified (≤6.0% for PFI Utility and the minimum requirement for making commercial pellets of DIN 51731 (>17500 J/g, respectively. Rice straw pellets have been a main type of biomass solid fuel and widely used. Bamboo pellets have better combustion properties compared with rice straw pellets. It is confirmed that bamboo pellets have great potential as biomass solid fuel, especially with respect to development of commercial pellets on an industrial scale in China. The information provided by this research is useful for development and utilization of bamboo resource and pellets.

  11. Thermo-Physical Properties of Micro-Cell UO2 Pellets and High Density Composite Pellets for Accident Tolerant Fuel

    This study presents the design and fabrication of micro-cell UO2 fuel pellets and high-density fuel pellets and also evaluates their out-of-pile performance. Micro-cell UO2 pellets are characterized by enhanced retention capability of their fission products and/or thermal conductivity. High-density pellets are composite pellets consisting of oxide and nitride components and they are expected to offer enhanced uranium density and thermal conductivity. (author)

  12. A 400-pellet feed system for the ORNL centrifuge pellet injector

    An improved and extended pellet fabrication and feed mechanism is being developed for the Oak Ridge National Laboratory (ORNL) centrifuge pellet injector that is presently installed on Tore Supra. This upgrade will extend the number of pellets available for a single-plasma discharge from 100 to 400. In addition, a new pusher and delivery system is expected to improve the performance of the device. As in the original system, deuterium ice is deposited from the gas phase on a liquid-helium-cooled rotating disk, forming a rim of solid deuterium. The rim of ice is machined to a parabolic profile from which pellets are pushed. In the new device, a stack of four ice rims are formed simultaneously, thereby increasing the capacity from 100 to 400 pellets. An improved method of ice formation has also been developed that produces clear ice. The pellet pusher and delivery system utilizes a four-axis, brushless dc servo system to precisely cut and deliver the pellets from the ice rim to the entrance of the centrifuge wheel. Pellets can be formed with sizes ranging from 2.5- to 4-mm diam at a rate of up to 8 per second. The operation of the injector is fully automated by a computer control system. The design and test results of the device are reported

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

    Shang, Lei; Dahl, Jonas; Ahrenfeldt, Jesper; Holm, Kens Kai; Nielsen, Niels Peter K.; Stelte, Wolfgang; Thomsen, Tobias; Bach, Lars Stougaard; Henriksen, Ulrik Birk

    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...

  14. TOMS Absorbing Aerosol Index

    Washington University St Louis — TOMS_AI_G is an aerosol related dataset derived from the Total Ozone Monitoring Satellite (TOMS) Sensor. The TOMS aerosol index arises from absorbing aerosols such...

  15. Sintering kinetics of mixed carbide pellets and trial production of pellets for irradiation tests

    Sintering kinetics of uranium-plutonium mixed carbides were determined, using the carbide powders having different particle size distributions. Single phase monocarbide pellets were fabricated in this experiment and some informations were obtained with regard to the relations between the density of sintered pellets and sintering time, and between shrinkage and sintering time. It was also found that porosity and grain size in the outer part of a pellet were different from those in its center. In addition, a trial production of carbide pellets for irradiation tests was carried and two kinds of pellets having different carbon contents were fabricated. It was observed in the trial production that the precipitates of the sesquicarbide accerelated sintering, while they retarded grain growth. (author)

  16. Metasurface Broadband Solar Absorber

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Milan Sykora; Nina R. Weisse-Bernstein; Luk, Ting S.; Antoinette J. Taylor; Dalvit, Diego A. R.; Hou-Tong Chen

    2016-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experiment...

  17. Swelling clay pellets. Elaboration and characterization

    Sealing structure, used in deep radioactive waste disposal, must prevent the radionuclides to diffuse to the biosphere. The main asset of pellets is their easy put in place. Yet porosity of such structures is higher and the swelling pressure lower in the structure performed with compacted blocks. As at such depth, hydraulic pressure could reach several MPa, the first goal of the study was to demonstrate that such a pressure does not alter the swelling pressure. A bibliographic study on the structural organisation of clayey media and stresses occurring in such media, associated to injection tests with high water pressure, has allowed- to validate the effective stress concept in saturated swelling clays and so to show that hydraulic pressure are not restrictive for using pellets. Different processes have also been studied to produce pellets: all of them give pellets with sizes around 20 mm and dry density higher than 1,90 g/cm3. Nevertheless, soaking test emphasised that porosity between pellets is to high to get a swelling pressure. Two approaches was then adopted to decrease this porosity: (i) mixing pellets with different sizes and (ii) mixing pellets with powder. In the first case, numerical calculation points out that, according to the processes, it would be better to use at least three different sizes to get the right porosity. in the second case, the introduction of pellets in the samples brings a new scale in the structural organisation (layer - particle - aggregate- pellet) in such a way that phenomena are more emphasized in the mixtures. Nevertheless, whatever the medium is like, the decrease of the axial and radial stresses during hydration is due to the decrease simultaneously to the increase of the swelling pressure. Finally, at same homogenized dry density heterogeneous and homogeneous samples have quite the same hydrodynamic and hydro-mechanical properties. That's why, it is suggested to describe heterogeneous media behaviour with modelling based on

  18. Technology and distribution of pellets. Experience about the European network on wood pellets

    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/m3. 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. Estimating shot distance from limited pellets pattern.

    Plebe, Alessio; Compagnini, Domenico

    2012-10-10

    Several methods are available for shooting range estimation based on pellets pattern on the target that have a remarkable degree of accuracy. The task is usually approached working under the assumption that the entire distribution of pellets is available for examination. These methods fail, however, when the victim has been hit by a portion of the pattern only. The problem can be solved with reasonable accuracy when there are areas of void in the victim that are adjacent to the area struck by pellets. This study presents a method that can be used in precisely this type of situation, allowing the estimation of shot distance in cases of partial pellet patterns. It is based on collecting distributions in test shots at several distances, and taking samples in the targets, constrained by the shape of the void and the pellet hit areas. Statistical descriptors of patterns are extracted from such samples, and fed into a neural network classifier, estimating shot ranges of distance. PMID:22658795

  20. Railgun pellet injection system for fusion experimental devices

    Onozuka, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Adv. Tech. Dev. Dept.; Oda, Y. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Adv. Tech. Dev. Dept.; Azuma, K. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Adv. Tech. Dev. Dept.; Satake, K. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Adv. Tech. Dev. Dept.; Kasai, S. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun 319-11 (Japan); Hasegawa, K. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun 319-11 (Japan)

    1995-11-01

    A railgun pellet injection system has been developed for fusion experimental devices. Using a low electric energy railgun system, hydrogen pellet acceleration tests have been conducted to investigate the application of the electromagnetic railgun system for high speed pellet injection into fusion plasmas. In the system, the pellet is pre-accelerated before railgun acceleration. A laser beam is used to induce plasma armature. The ignited plasma armature is accelerated by an electromagnetic force that accelerates the pellet. Under the same operational conditions, the energy conversion coefficient for the dummy pellets was around 0.4%, while that for the hydrogen pellets was around 0.12%. The highest hydrogen pellet velocity was 1.4 km s{sup -1} using a 1 m long railgun. Based on the findings, it is estimated that the hydrogen pellet has the potential to be accelerated to 5 km s{sup -1} using a 3 m long railgun. (orig.).

  1. Development of pellet melting temperature measurement apparatus

    In the extended fuel burn-up project of the light water reactor (LWR), the irradiation behavior of high burn-up fuels should be clarified. Data accumulation of thermal properties such as melting point of LWR fuel pellets is quite urgent from the view point of safety evaluation in the normal operation and accident conditions. In the department of Hot Laboratories, several apparatuses have been developed for investigating the irradiation behavior of high burn-up fuels under the consignment of the Science and Technology Agency since 1990. A pellet Melting Temperature measurement apparatus was developed as one of them. This paper describes outline and characteristic test of the apparatus, and measurements of melting point of unirradiated and irradiated UO2 pellets. (author)

  2. Development of pellet injection systems for ITER

    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

  3. Method of filling fuel pellets into a fuel can

    Purpose: To prevent a fuel can from deformation due to edges of pellets and occurrence of stress, by rearranging and filling fuel pellets of bad rectangularity into fuel cans. Methof: A plurality of fuel pellets of bad rectangularity are arranged on a arranging plate fitted with a vibrator, and are forced with springs at both ends. The vibrator is energized to vibrate and rotate the pellets so that they are regularly rearranged. Each fuel can is provided with X-Y lines to match the directions of pellets, and rearranged UO2 pellet stack is slided into the can with the directions matched. (Nakamura, S.)

  4. Fuel Pellets Production from Biodiesel Waste

    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.

  5. Dysprosium hafnate as absorbing material for control rods

    Dysprosium hafnate is proposed as a promising absorbing material for control rods of thermal nuclear reactors. The properties of dysprosium hafnate pellets with different Dy and Hf contents are presented in this article. The fluorite phase is characterized by the density range 6.8-7.8 g/cm3 and; the thermal diffusivity achieves 0.58-0.83 mm2/s at 20 deg. C, thermal conductivity of 1.5-2.0 W/(K m) and TLEC of (8.4-8.6) x 10-6 K-1 at 20 deg. C. The temperature dependence of the thermophysical properties of dysprosium hafnate are presented. The neutron absorption efficiency of dysprosium hafnate was estimated in comparison with boron carbide. The radiation resistance of pellets after irradiation in the BOR-60 reactor is presented as well

  6. Quality control of (Th,Pu)O2 fuel pellet obtained by coated agglomerate pelletization

    (Th,Pu)O2 fuel pellets were synthesised by coated agglomerate pelletization route and characterized for the chemical quality control. (Th,Pu)O2 pellets were characterized for trace metals by spectrometric methods and non metals by ion chromatographic, spectrophotometric, conductometric and manometric methods. H, F, B and Cd contents were found to be less than 1 ppm while that for V and Cl were found to be less than 10 ppm. The pellets were found to contain Cr, Cu, Mo, Na, Ni and Pb in the range of 10-50 ppm whereas Zn, Al, Ca and C in the range of 50-100 ppm. More than 100 ppm Si, Fe and Mg were found to be present in the (Th,Pu)O2 pellets. The O/M content of the pellets were found to be ∼2.00. A comparative study on (Infrared) I.R. and microwave (microwave) dissolution were also used to ascertain the Th and Pu content in the (Th,Pu)O2 pellets. (author)

  7. Pellet ablation and ablation model development

    A broad survey of pellet ablation is given, based primarily on information presented at this meeting. The implications of various experimental observations for ablation theory are derived from qualitative arguments of the physics involved. The major elements of a more complete ablation theory are then outlined in terms of these observations. This is followed by a few suggestions on improving the connections between theory and experimental results through examination of ablation data. Although this is a rather aggressive undertaking for such a brief (and undoubtedly incomplete) assessment, some of the discussion may help us advance the understanding of pellet ablation. 17 refs

  8. International Trade of Wood Pellets (Brochure)

    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.

  9. Pellet impact drilling operational parameters: experimental research

    The article deals with the study of particle-impact drilling that is designed to enhance the rate-of-penetration function in hard and tough drilling environments. It contains the experimental results on relation between drilling parameters and drilling efficiency, the experiments being conducted by means of a specially designed laboratory model. To interpret the results properly a high-speed camera was used to capture the pellet motion. These results can be used to choose optimal parameters, as well as to develop enhanced design of ejector pellet impact drill bits

  10. Implantation of methodology for determination of fluorine and chlorine contents in fuel pellets by pyrohydrolysis at CDTN-MG (Brazil)

    The system and the methodology that were developed to perform fuel pellets quality control at CDTN, in relation to fluorine and chlorine contents by pyrohydrolysis ion-selective electrode method, are shown. The method is based on the separation of these halogens in the presence of wet oxygen, in a temperature ranging from 950 to 1.100 deg C. Fluoride and chloride are volatilized as acids, absorbed in a potassium acetate buffer solution, and measured with ion-selective electrodes. The system was utilized to perform the quality control of uranium dioxide and thorium and uranium mixed oxide fuel pellets, manufactured to research cooperative programs between Brazil and Germany. The obtained results showed that the pellets presented contents of such impurities lower than the maximal limits required by the specifications of these fuels. (author)

  11. Wood pellets in a power plant - mixed combustion of coal and wood pellets

    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 SO2 and NOx emissions slightly. Simultaneously the CO2 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

  12. Decay rate of reindeer pellet-groups

    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

  13. Metasurface Broadband Solar Absorber

    Azad, A K; Sykora, M; Weisse-Bernstein, N R; Luk, T S; Taylor, A J; Dalvit, D A R; Chen, H -T

    2015-01-01

    We demonstrate a broadband, polarization independent, omnidirectional absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low emissivity at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. Furthermore, we discuss the potential use of our metasurface absorber design in solar thermophotovoltaics by exploiting refractory plasmonic materials.

  14. An absorbed dose microcalorimeter

    A graphite microcalorimeter is described for use as a primary standard of ionising radiation absorbed dose; its place in the hierarchy of Australian ionising radiation standards is discussed. A disc shaped absorber is supported on pins within three nested graphite jackets and an insulated vacuum vessel. Calibration heating is by thermistor, the feasibility of this was verified by computer modelling. Adiabatic and heat-flow modes of operation are described, and calculations of heat transfer between the various graphite parts are summarised. Carbon and water phantoms were built for the evaluation of correction factors for the microcalorimeter, and for the calibration of radiotherapy dosemeters. The microcalorimeter will be used as a working standard for the calibration of dosemeters in terms of absorbed dose for the x-ray, gamma-ray and electron radiotherapy beams commonly used in Australia today

  15. Production and injection of hydrogen-deuterium mixed pellet

    A mixed solid pellet of hydrogen and deuterium could be produced in the single pellet injector. The pellet is used to examine an improvement of plasma confinement in ion cyclotron range of frequency (ICRF) wave heated discharges. The mixed pellets were maken from the mixed gas with the different ratio of hydrogen to mixed gas (H + D). The composition of the pellet is not equal to that of the mixed gas before freezing. The in-flight mixed pellets with about 769 m/s keep their cylindrical shape, e.g. the pellets are not broken. The present results will indicate the possibility of pellet mixed deuterium and tritium, which will be necessary to in future thermonuclear fusion reactor. (author)

  16. Production of wood pellets. Research and development and standardisation

    Due to the rapidly increasing market of wood pellets new standards and certification systems especially for high quality pellets have been developed in Austria and Germany. An overview about the most important standards and about the market situation are given. Apart from national standardization activities on European level 28 standards for solid biofuels are being elaborated. At Holzforschung Austria a four year research project on wood-pellets deals with specifically influencing parts of the pellet production process: preconditioning of raw material (storage conditions, drying, softening of lignin), alternative pressing aids, cooling of pellets and post-treatment with coating substances in order to increase pellet quality. The main objective is to improve abrasion resistance and hygroscopicity of the pellets. The tests have been mainly carried out with a ring-die laboratory pellet press. (authors)

  17. Jet pellet ablation studies and projections for CIT and ITER

    Pellet penetration in JET is analyzed and compared with predictions of the neutral gas and plasma shielding (NGPS) model for pellet ablation. The model is then used to evaluate pellet penetration in CIT and ITER. A simplified scaling law is derived for pellet penetration when the shielding is dominated by the cold ablatant plasma. Comparison with a similarly derived scaling law for the original neutral gas shielding (NGS) model shows that pellet size and plasma electron temperature dependences are similar, but velocity scaling is reduced or completely absent in the NGPS model. We show that projected penetration for higher-velocity pellets may be erroneous with the NGPS model. If the neutral gas shield dominates, as it probably does if the neutral gas shield is elongated along the magnetic field, pellet penetration in JET, CIT, and ITER can be significantly enhanced with higher pellet velocities. 13 refs., 2 figs., 2 tabs

  18. Irradiation performances of the Superphenix type absorber element

    Several aspects of irradiation behaviour of the SUPERPHENIX type absorber element are presented in this paper. A large programme of irradiation tests was performed in PHENIX to assess and to improve the absorber pin design whose main characteristics for the first load are a sodium bonded and vented pin with high density (96% TD) and highly enriched (up to 90 at % of boron 10) B4C pellets. We present and discuss the main post-irradiation results obtained by this program which concerns the behaviour of both B4C pellets (fragmentation, swelling, helium release, thermal conductivity evolution) and stainless steel clad (embrittlement by carburization, mechanical interaction). It appears that the residence time of the first load of SUPERPHENIX control rods is clearly limited by mechanical interaction between B4C and the clad, and particularly by relocating of small fragments of B4C at beginning of life of the first gap. The irradiation performed in PHENIX led to fix the residence time of the first load of control rods to 240 e.f.p.d. The analyses of the effects limiting the residence time have enabled us to propose an extension of this time by two measures. The first one is reduction of the capture rate in boron carbide. The measure was brought into operation by mean of lowering at 48 at % the boron 10 enrichment of the B4C pellets in the lower part of the pin. The second measure is preventing the fragment relocation by adoption of a thin stainless shroud enclosing the pellet stack. The efficiency of these measures was proved in several irradiation tests (ANTIMAG experiments) in PHENIX. A burn-up of 220 x 1020 capt/cm3 was achieved without any dimensional change of the pin diameter. The shroud failed but could nevertheless prevent any pellet cladding deformation. Thus, these results have enabled us to fix a residence time of 640 e.f.p.d. for the third load of the SUPERPHENIX control rods. The achievement in the future of lifetime up to 1000 e.f.p.d. will require the

  19. Pellet injection experiments on the TFR Tokamak

    Single pellet injection experiments have been carried out on TFR with the aim to improve the experimental knowledge of ablation physical processes and also to get a better description of the heat and matter transport during and after pellet evaporation. Ablation clouds have been photographed, providing experimental penetration depths in rough agreement with the neutral shielding model. Observation of striations in the cloud has led to an experimental determination of the safety factor profile. Parameters of the plasma in the ablation cloud have been spectroscopically determined. Fast heat transport has been evidenced during pellet evaporation (∼ 100 μs) which exhibits some features of minor or major disruptions (appearance of a m = 1, n = 1 island on the q = 1 surface, bursts of density fluctuations, comparable heat diffusivity, ...). Matter transport takes place on a larger time scale (∼ 10 ms). This long temporal relaxation is well accounted for by the 1D-MAKOKOT computer code without changing the transport coefficients after pellet injection. Heat and matter transport are affected by the presence of the m = 1, n = 1 island on the q = 1 surface

  20. Alpha particle diagnostics using impurity pellet injection

    We have proposed using impurity injection to measure the energy distribution of the fast confined alpha particles in a reacting plasma. The ablation cloud surrounding the injected pellet is thick enough that an equilibrium fraction Fo∞(E) of the incident alphas should be neutralized as they pass through the cloud. By observing neutrals created in the large spatial region of the cloud which is expected to be dominated by the helium-like ionization state, e.g., Li+ ions, we can determine the incident alpha distribution dnHe2+/dE from the measured energy distribution of neutral helium atoms. Initial experiments were performed on TEXT in which we compared pellet penetration with our impurity pellet ablation model, and measured the spatial distribution of various ionization states in carbon pellet clouds. Experiments have recently begun on TFTR with the goal of measuring the alpha particle energy distribution during D-T operation in 1993--94. A series of preliminary experiments are planned to test the diagnostic concept. The first experiments will observe neutrals from beam-injected deuterium ions and the high energy 3He tail produced during ICH minority heating on TFTR interacting with the cloud. We will also monitor by line radiation the charge state distributions in lithium, boron, and carbon clouds

  1. New Results with the Ignitor Pellet Injector

    Frattolillo, A.; Migliori, S.; Podda, S.; Bombarda, F.; Baylor, L. R.; Combs, S. K.; Foust, C. R.; Meitner, S.; Fehling, D.; Roveta, G.

    2011-10-01

    The Ignitor Pellet Injector (IPI) has been developed in collaboration between ENEA and ORNL to provide greater control over the density time evolution and the density peaking in plasmas produced by the Ignitor device. The four barrel, two stage injector has been designed to reach speeds up to 4 km/s, for effective low field side injection into ignited plasmas (Te ≅Ti ≅ 11 keV). The present arrangement accomodates both a two-stage gun and a standard propellant valve on each barrel, allowing seamless switching between standard and high speed operation on any or all gun barrels. The cryostat is actively cooled by a pulse tube refrigerator, equipped with supplemental cooling from a liquid He dewar. The injector has shown very good repeatability; however, intact pellets were not observed over 2 km/s, possibly due to a spinning effect on the pellets at higher speed. The cross sections of the guiding tubes have been increased and other design improvements have been implemented, aimed in particular at reducing leak rates and reducing the dispersion of the pellet trajectories, in preparation of the experimental campaign reported here. Sponsored in part by ENEA of Italy, and by the U.S. D.O.E.

  2. Co-gasification of pelletized wood residues

    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}.

  3. Development of D2 Pellet Injectors

    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...

  4. Experiences with RDF pellets in a gasifier

    Decreasing dependence upon landfills means MSW recycling and organic diversion programs grow but there is still waste remaining. A community near Toronto is turn the residuals into pellets augmented with high calorific value industry wastes. The pellet fuel has reduced ash, trace metal, and halogen concentrations when compared to MSW. Some of these pellets are being used to heat a greenhouse in southwestern Ontario using a chain grate gasifier and boiler system. This paper discusses some of the results of the initial operation and testing of a pair of these units. The gasifier has evolved and is currently rated at 20.2 GJ/h, consuming up to 940 kg/h of RDF pellets or the thermal equivalent in wood pellets. Twounits, with hot water storage tanks, are sufficient to satisfy the greenhouses 50 GJ/hr heating needs. The units boiler exhausts are treated with powdered lime before passing through separate fabric filter systems. One fabric filter was equipped with REMEDIA bags for PCDD/F removal, the other had a typical fibreglass filter. A combination of recirculated flue gas and fresh combustion air is blown up through the grate and fuel bed, into three independently controlled combustion zones. Under fire air oxygen levels are used to control temperatures within the gasification chamber. A smaller unit, 3.78 GJ/h capacity, was tested twice in 2008 and the current version was tested in early 2009. More tests are planned for the spring of 2010. While the tests have generally shown excellent emission performance, mercury, chlorine, and PCDD/F have been higher than anticipated. The finding of elevated levels of Cl2 in the exhaust gasses has been suggested as the main reason for the unusually high PCDD/F emissions. The findings related to chlorine and PCDD/F in this process is the main thrust of the paper. (author)

  5. Results of pellet injection experiments in JT-60

    This paper presents recent experimental results of pellet injection to joule plasma and heating experiments of pellet injected plasma by NB, LHRF, and ICRF. Especially clear improvement in confinement has been obtained in NB heating of pellet injected plasma up to 10-15 MW in Ip = 1.5-1.8 MA lower-side X-point divertor configuration. (author)

  6. Transonic ablation flow regimes of high-Z pellets

    Kim, Hyoungkeun; Parks, Paul

    2015-01-01

    In this letter, we report results of numerical studies of the ablation of argon and neon pellets in tokamaks and compare them with theoretical predictions and studies of deuterium pellets. Results demonstrate the influence of atomic physics processes on the pellet ablation process.

  7. Development and problems of pellet markets in Austria

    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

  8. Fuel Pellets from Wheat Straw: The Effect of Lignin Glass Transition and Surface Waxes on Pelletizing Properties

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

    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 woody biomass. Straw has a lower lignin content 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...... effect is observed at elevated temperatures. Fuel pellets made from extracted wheat straw have a slightly higher compression strength which might be explained by a better interparticle adhesion in the absence of hydrophobic surface waxes....

  9. Influence of acrylic esters and methacyrlic esters on flotation of pellets and release rate of verapamil hydrochloride.

    Lunio, Rafał; Sawicki, Wiesław

    2006-01-01

    Eudragit RL (ERL) and Eudragit RS (ERS) are biocompatible cationic copolymers, pH-independent and insoluble in aqueous environment. In this study drug delivery system consisting of a capsule filled with floating pellets with verapamil hydrochloride (VH) is proposed. The release of VH in the stomach results in better solubility in an acid gastric environment in vivo and may result in greater amount of the VH absorbed and its higher concentration in plasma. The scope of this study was to investigate the influence of ERL and ERS ratio on VH release in 0,1 M HCl from floating coating pellets. The stability of this film was also investigated. The ERL film is much more permeable than ERS, and an increase of ERL film thickness did not retard the release rate. The combination of ERL and ERS are forms of the sustained release film. It was a necessary to add the uncoated pellets, which constituted the initial dose. The start of flotation depends on permeability of polymeric film, and decreases with addition of ERS. There is no change in the start flotation time after 12 months under room condition (25 degrees C/60% RH). The drug delivery from uncoated pellets and pellets coated with ERL/ERS is stable after 12 months under room condition (25 degrees C/60% RH). PMID:17515332

  10. Negative impedance shunted electromagnetic absorber for broadband absorbing: experimental investigation

    The traditional tuned mass absorber is widely employed to control the vibration of a primary structure by transferring the vibrating energy to the absorber. However, the working band of the absorber is very narrow, which limits the application of broadband vibration control. This study presents a novel broadband electromagnetic absorber by first introducing two negative impedance shunts to improve broadband damping of the absorber. The electromagnetic absorber is modeled, and the corresponding electromagnetic coupling coefficient is tested. A cantilever beam is employed to verify the broadband vibration absorption of the negative resistance (NR) shunted electromagnetic absorber (NR absorber) and the negative inductance NR shunted electromagnetic absorber (NINR absorber). The governing equations of the beam with two absorbers are derived, and the experiments are set up. The results point out that the NR and NINR absorbers can attenuate the broadband vibration. The proposed absorbers do not need the feedback system and the real-time controller compared to the active absorber; hence, they have great application potential in aerospace and in submarine applications, as well as in civil and mechanical engineering. (paper)

  11. Optimization of backfill pellet properties AASKAR DP2 - Laboratory tests

    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

  12. Optimization of backfill pellet properties AASKAR DP2-Laboratory tests

    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

  13. Effectiveness of using burnable absorbers in a VVER-1000

    The operational efficiency and safety of a nuclear reactor depends on the method used to compensate its excess reactivity. In a VVER-1000, along with the boron dissolved in the water in the primary coolant loop, the excess reactivity is compensated with a burnable absorber. The main purpose of using burnable absorber rods as a method to compensate for part of the excess reactivity instead of a liquid absorber is to provide the reactor negative feedback with respect to the coolant temperature and consequently to make it self-regulating. There are disadvantages associated with burnable poisons that can be partially corrected by using another type of absorber - an integral absorber. Examples of such an absorber are gadolinium, integrated in the form of an oxide (Gd2O3) with the fuel, and boron, which is incorporated in the form of zirconium diboride (ZrB2) on the surface of the fuel pellets. Successful experience has been accumulated abroad in using both uranium - gadolinium fuel and fuel coated with a thin film containing ZrB2 in PWRs. The effectiveness of using different types of burnable absorbers in a VVER-1000 was investigated, using a stationary three-year fuel cycle as an example. The neutron physics characteristics of the reactor were calculated using the KASSETA-OKA-BIPR-KR program package. The results of the comparative calculations of the fuel loading characteristics of a VVER-1000 show that replacing lumped absorbers with integral ones demonstrates a real possibility of improving the economic indices and safety of nuclear power plants with VVER's

  14. Pelletization processes for pharmaceutical applications: a patent review.

    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. PMID:21143125

  15. Simulation of peeling-ballooning modes with pellet injection

    Chen, S. Y. [College of Physical Science and Technology, Sichuan University, 610064 Chengdu (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Southwestern Institute of Physics, Chengdu 610041 (China); Huang, J.; Sun, T. T.; Tang, C. J. [College of Physical Science and Technology, Sichuan University, 610064 Chengdu (China); Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 (China); Wang, Z. H. [Southwestern Institute of Physics, Chengdu 610041 (China)

    2014-11-15

    The influence of pellet ablation on the evolution of peeling-ballooning (P-B) modes is studied with BOUT++ code. The atoms coming from pellet ablation can significantly reshape the plasma pressure profile, so the behaviors of P-B modes and edge localized mode (ELM) are modified dramatically. This paper shows that the energy loss associated with an ELM increases substantially over that without the pellet, if the pellet is deposited at the top of the pedestal. On the contrary, for pellet deposition in the middle of the pedestal region the ELM energy loss can be less.

  16. Simulation of peeling-ballooning modes with pellet injection

    The influence of pellet ablation on the evolution of peeling-ballooning (P-B) modes is studied with BOUT++ code. The atoms coming from pellet ablation can significantly reshape the plasma pressure profile, so the behaviors of P-B modes and edge localized mode (ELM) are modified dramatically. This paper shows that the energy loss associated with an ELM increases substantially over that without the pellet, if the pellet is deposited at the top of the pedestal. On the contrary, for pellet deposition in the middle of the pedestal region the ELM energy loss can be less

  17. Development of Advanced Pellet Injector Systems for Plasma Fueling

    SAKAMOTO, Ryuichi; Yamada, Hiroshi; LHD Experimental Group

    2009-01-01

    Two types of solid hydrogen pellet injection systems have been developed, and plasma refueling experiments have been performed using these pellet injectors. One is an in-situ pipe-gun type pellet injector, which has the simplest design of all pellet injectors. This in-situ pipe-gun injector has 10 injection barrels, each of which can independently inject cylindrical solid hydrogen pellets (3.4 and 3.8mm in diameter and length, respectively) at velocities up to 1,200m/s. The other is a repetit...

  18. Pelletizing and combustion of wood from thinning; Pelletering och foerbraenning av gallringsvirke

    Oerberg, Haakan; Thyrel, Mikael; Kalen, Gunnar; Larsson, Sylvia

    2007-12-14

    This work has been done in order to find new raw material sources for an expanding pellet industry, combined with finding a use for a forest product that has no market today. The raw material has been forest from early thinning in two typical stands in Vaesterbotten. The purpose has been to evaluate this material as a raw material for producing pellets. Two typical stands have been chosen. One stand with only pine trees and one mixed stand dominated by birch. The soil of these stands was poor. Half of the trees were delimbed by harvest and half of the trees were not delimbed. This formed four different assortments that were handled in the study. After harvesting the assortments were transported to an asphalt area to be stored. Half of the material was stored during one summer and half of the material was stored during one year and one summer. The different assortments were upgraded to pellets and test combusted in the research plant BTC at the Swedish University of Agricultural Sciences, in Umeaa. The upgrading process contains of the following steps: 1.Chipping by a mobile chipper. 2.Low temperature drying (85 deg C). 3. Coarse shredding ({phi}15 mm). 4. Fine shredding ({phi}4-6 mm) and 5. Pelletizing (Die: {phi}8). Samples for fuel analysis were taken during the chipping. Analyses shows that the net calorific value for delimbed assortments are about 0,3 MJ/kg DM higher than for limbed assortments. Pellets made of the assortments Mixed limbed and Pine limbed has shown a net calorific value comparable to stem wood pellets. Pellets made of Birch delimbed show a net calorific value 0,4 MJ/kg DM lower than stem wood pellets. Analyses show that ash contents of the assortment Mixed delimbed was 1 %-unit higher compared to stem wood pellets. The assortment Pine delimbed and Birch delimbed has showed an ash contents comparable with stem wood pellets. The ash melting characteristics can reduce the value of a raw material. Low ash melting temperature for a fuel might cause

  19. Metasurface Broadband Solar Absorber

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  20. Universal metamaterial absorbe

    Smaali, Rafik; Moreau, Antoine; Taliercio, Thierry; Centeno, Emmanuel

    2016-01-01

    We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\\lambda/100$ thickness by a metamaterial layer and a mirror. An extraordinary large funneling through nano-slits explains how light can be trapped in the structure. Simple scaling laws can be used as a recipe to design ultra-thin perfect absorbers whatever the materials and the desired resonance wavelength, making our design truly universal.

  1. Absorbable and biodegradable polymers

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  2. Universal metamaterial absorbe

    Smaali, Rafik; Omei, Fatima; Antoine MOREAU; Taliercio, Thierry; Centeno, Emmanuel

    2016-01-01

    We propose a design for an universal absorber, characterized by a resonance frequency that can be tuned from visible to microwave frequencies independently of the choice of the metal and the dielectrics involved. An almost resonant perfect absorption up to 99.8 % is demonstrated at resonance for all polarization states of light and for a very wide angular aperture. These properties originate from a magnetic Fabry-Perot mode that is confined in a dielectric spacer of $\\lambda/100$ thickness by...

  3. Quality properties of fuel pellets from forest biomass

    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.

  4. An advanced cold moderator using solid methane pellets

    Foster, C.A. [Cryogenic Applications F, Inc., Clinton, TN (United States); Carpenter, J.M. [Argonne National Laboratory, Argonne, Illinois (United States)

    2001-03-01

    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)

  5. High-rate behaviour of iron ore pellet

    Gustafsson Gustaf

    2015-01-01

    Full Text Available Iron ore pellets are sintered, centimetre-sized spheres of ore with high iron content. Together with carbonized coal, iron ore pellets are used in the production of steel. In the transportation from the pelletizing plants to the customers, the iron ore pellets are exposed to different loading situations, resulting in degradation of strength and in some cases fragmentation. For future reliable numerical simulations of the handling and transportation of iron ore pellets, knowledge about their mechanical properties is needed. This paper describes the experimental work to investigate the dynamic mechanical properties of blast furnace iron ore pellets. To study the dynamic fracture of iron ore pellets a number of split Hopkinson pressure bar tests are carried out and analysed.

  6. Tritium pellet injection sequences for TFTR

    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 nonoptimized 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

  7. Deuterium pellet injection in the TFR Tokamak

    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)

  8. On the pelletizing of sulfide molybdenite concentrate

    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 % MoS2) 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

  9. Summary of fueling by pellet injection

    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

  10. Method of manufacturing nuclear fuel pellet

    The present invention concerns a method of manufacturing nuclear fuel pellets. As nuclear fuel materials, uranium oxide such as uranium dioxide, plutonium oxide and thorium oxide, etc. are used alone or as a mixture of two or more of them. At first, reactivity of raw material powders is increased to higher than a predetermined level by a pulverizing and pelletizing treatment. Next, U3O8 or an organic material which decomposes at a high temperature is added to by 0.1 to 2.0 % by weight as a pore former to the pulverization and pelletization product. Then, press-molding is applied within a range of pressure from 1.0 to 5.0 ton/cm3, to provide a molding density of higher than 6.0 g/cc. Then, heat treatment is applied under the condition at a temperature of 800 to 1100degC in a non-reducing atmosphere such as in Ar, N2, He or CO2, to remove the pore former added. Then sintering is applied at 1400 to 1800degC in H2 or a mixed atmosphere of H2 and N2. This can improve the production efficiency. (I.N.)

  11. Production of hydrogen, nitrogen and argon pellets with the Moscow-Juelich pellet target

    Targets of frozen droplets ("pellets") from various liquefiable gases like H2, D2, N2, Ne, Ar, Kr and Xe are very promising for high luminosity experiments with a 4π detector geometry at storage-rings. High effective target densities (> 1015atoms/cm2), a small target size (⊘ ≈ 20–30 μm), a low gas load and a narrow pellet beam are the main advantages of such targets. Pioneering work on pellet targets has been made at Uppsala, Sweden. A next generation target has been built at the IKP of FZJ in collaboration with two institutes (ITEP and MPEI) from Moscow, Russia. It is a prototype for the future pellet target at the PANDA experiment at FAIR/HESR (supported by INTAS 06-1000012-8787, 2007/08) and makes use of a new cooling and liquefaction method, based on cryogenic liquids instead of cooling machines. The main advantages of this method are the vibration-free cooling and the possibility for cryogenic jet production from various gases in a wide range of temperatures. Different regimes of pellet production from H2, N2 and Ar have been observed and their parameters have been measured. For the first time, mono-disperse and satellite-free droplet production was achieved for cryogenic liquids from H2, N2 and Ar. (author)

  12. Producing bio-pellets from sunflower oil cake for use as an energy source

    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)

  13. Absorber for terahertz radiation management

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  14. Corrosion resistant neutron absorbing coatings

    Choi, Jor-Shan; Farmer, Joseph C.; Lee, Chuck K.; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  15. Corrosion resistant neutron absorbing coatings

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  16. Investigation of pellet acceleration by an arc heated gas gun

    This report describes work on pellet acceleration by means of an arc heated gas gun. The work is a continuation of the work described in RISO-M-2536. The aim of the work is to obtain velocities well above 2 km/s for 3.2 mm diameter deuterium pellets. By means of a cryogenic arc chamber in which the hydrogen propellant is pre-condensed, extruded deutetrium pellets are accelerated up to a maximum velocity of 1.93 km/s. When increasing the energy input to the arc in order to increase the pellet velocity further the heat input to the extrusion/punching pellet loading mechanism was found to be critical: preparation of pellets became difficult and cooling times between shots became inconveniently long. In order to circumvent this problems the concept of a room temperature hydrogen propellant pellet fed arc chamber was proposed. Preliminary results from acceleration of polyurethane pellets with this arc chamber are described as well as the work of developing of feed pellet guns for this chamber. Finally the report describes design consideration for a high pressure propellant pellet fed arc chamber together with preliminary results obtained with a proto-type arc chamber. (author)

  17. RECENT DEVELOPMENTS IN BIOMASS PELLETIZATION – A REVIEW

    Wolfgang Stelte,

    2012-07-01

    Full Text Available The depletion of fossil fuels and the need to reduce greenhouse gas emissions has resulted in a strong growth of biomass utilization for heat and power production. Attempts to overcome the poor handling properties of biomass, i.e. its low bulk density and inhomogeneous structure, have resulted in an increasing interest in biomass densification technologies, such as pelletization and briquetting. The global pellet market has developed quickly, and strong growth is expected for the coming years. Due to an increase in demand for biomass, the traditionally used wood residues from sawmills and pulp and paper industry are not sufficient to meet future needs. An extended raw material base consisting of a broad variety of fibrous residues from agriculture and food industries, as well as thermal pre-treatment processes, provides new challenges for the pellet industry. Pellet production has been an established process for several decades, but only in the past five years has there been significant progress made to understand the key factors affecting pelletizing processes. A good understanding about the pelletizing process, especially the processing parameters and their effect on pellet formation and bonding are important for process and product optimization. The present review provides a comprehensive overview of the latest insights into the biomass pelletization processes, such as the forces involved in the pelletizing processes, modeling, bonding, and adhesive mechanisms. Furthermore, thermal pretreatment of the biomass, i.e. torrefaction and other thermal treatment to enhance the fuel properties of biomass pellets are discussed.

  18. A fuel pellet injector for the Microwave Tokamak Experiment (MTX)

    Unlike other fueling systems for magnetically confined fusion plasmas, a pellet injector can deliver many fuel gas particles to the core of the plasma, enhancing plasma confinement. We installed a new pellet injector on the MTX (formerly Alcator-O) to provide a plasma with a high core density for experiments both with and without ultrahigh-power microwave heating. Its four-barrel pellet generator is the first to be designed and built at LLNL. Based on 'pipe-gun'' technology originated at Oak Ridge National Laboratory (ORNL), it incorporates our structural and thermal engineering innovations and a unique control system. The pellet transport, differential vacuum-pumping stages, and fast-opening propellant valves are reused parts of the Impurity Study EXperiment (ISX) pellet injector built by ORNL. We tailored designs of all other systems and components to the MTX. Our injector launches pellets of frozen hydrogen or deuterium into the MTX, either singly or in timed bursts of up to four pellets at velocities of up to 1000 m/s. Pellet diameters range from 1.02 to 2.08 mm. A diagnostic stage measures pellet velocities and allows us to photograph the pellets in flight. We are striving to improve the injector's performance, but its operations is already very consistent and reliable

  19. Mycelial pellet formation by edible ascomycete filamentous fungi, Neurospora intermedia.

    Nair, Ramkumar B; Lennartsson, Patrik R; Taherzadeh, Mohammad J

    2016-12-01

    Pellet formation of filamentous fungi in submerged culture is an imperative topic of fermentation research. In this study, we report for the first time the growth of filamentous ascomycete fungus, Neurospora intermedia in its mycelial pellet form. In submerged culture, the growth morphology of the fungus was successfully manipulated into growing as pellets by modifying various cultivation conditions. Factors such as pH (2.0-10.0), agitation rate (100-150 rpm), carbon source (glucose, arabinose, sucrose, and galactose), the presence of additive agents (glycerol and calcium chloride) and trace metals were investigated for their effect on the pellet formation. Of the various factors screened, uniform pellets were formed only at pH range 3.0-4.0, signifying it as the most influential factor for N. intermedia pellet formation. The average pellet size ranged from 2.38 ± 0.12 to 2.86 ± 0.38 mm. The pellet formation remained unaffected by the inoculum type used and its size showed an inverse correlation with the agitation rate of the culture. Efficient glucose utilization was observed with fungal pellets, as opposed to the freely suspended mycelium, proving its viability for fast-fermentation processes. Scale up of the pelletization process was also carried out in bench-scale airlift and bubble column reactors (4.5 L). PMID:27103628

  20. Prolonged release matrix pellets prepared by melt pelletization. I. Process variables

    Thomsen, L.J.; Schaefer, T.; Sonnergaard, Jørn;

    1993-01-01

    A melt pelletization process was investigated in an 8 litre laboratory scale high shear mixer using a formulation with paracetamol, glyceryl monostearate 40-50, and microcrystalline wax. The effects of jacket temperature, product temperature during massing, product load, massing time and impeller...... speed were investigated by means of factorially designed experiments. The maximum yield of pellets in the range of 500-1400 μm was found to approx. 90%. For process conditions preventing deposition of moist mass, the process was found to be reproducible. Impeller speed and massing time were found to be...

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

    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 [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: ranf@cdtn.br, e-mail: antdrade@gmail.com, e-mail: odairm@cdtn.br, e-mail: pabloag@cdtn.br, e-mail: dmc@cdtn.br, e-mail: flmigliorini@hotmail.com, e-mail: egonn@ufmg.br

    2009-07-01

    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{center_dot}cm{sup -3} up to 10.08 g{center_dot}cm{sup -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{sup -6}m{sup 2}{center_dot}s{sup -1} up to 2.78 x 10{sup -6}m{sup 2}{center_dot}s{sup -1} and thermal conductivity from 6.22 m{sup -1}{center_dot}K{sup -1} up to 7.24 W{center_dot}m{sup -1}{center_dot}K{sup -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. (au0010th.

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

    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 10-6m2·s-1 up to 2.78 x 10-6m2·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)

  3. Sensing with THz metamaterial absorbers

    Cong, Longqing

    2014-01-01

    Metamaterial perfect absorbers from microwaves to optical part of the electromagnetic spectrum has been intensely studied for its ability to absorb electromagnetic radiation. Perfect absorption of light by metamaterials have opened up new opportunities for application oriented functionalities such as efficient sensors and emitters. We present an absorber based sensing scheme at the terahertz frequencies and discuss optimized designs to achieve high frequency and amplitude sensitivities. The major advantage of a perfect metamaterial absorber as a sensor is the sensitive shift in the absorber resonance frequency along with the sharp change in the amplitude of the resonance due to strong interaction of the analyte with the electric and the magnetic fields at resonant perfect absorption frequency. We compare the sensing performance of the perfect metamaterial absorber with its complementary structural design and planar metasurface with identical structure. The best FoM values obtained for the absorber sensor here...

  4. New ceramic fuel pellet for a nuclear reactor

    These ceramic fuel pellets, for nuclear fuel elements with a metal cladding tube and which are axisymmetrical, are characterized in that their diameter at each end is less than the diameter midway from the ends. They are based on at least one fissile or fertile compound. Each end area is truncated in shape. The generating line of the truncated area is slanted in relation to the axis of the pellet at an angle of 0.2 to 30. They have a cylindrical area included between the end areas. The difference between the maximum and minimum diameters of the pellet is around one to ten times the initial transversal play between the pellet and the cladding tube wall in the area of maximum pellet diameter. These new pellets make it possible to avoid the risks of cladding cracks and hence the premature shut-down of the reactor

  5. Pellet injectors for the tokamak fusion test reactor

    The repeating pneumatic injector is a device from the ORNL development program. A new eight-shot deuterium pellet injector has been designed and constructed specifically for the TFTR application and is scheduled to replace the repeating injector this year. The new device combines a cryogenic extruder and a cold wheel rotary mechanism to form and chamber eight pellets in a batch operation; the eight pellets can then be delivered in any time sequence. Another unique feature of the device is the variable pellet size with three pellets each of 3.0 and 3.5 mm diam and two each of 4.0 mm diam. The experience and technology that have been developed on previous injectors at ORNL have been utilized in the design of this latest pellet injection system

  6. Studies of hydrogen pellet acceleration with fuseless electromagnetic railgun

    A fuseless circular-bore electromagnetic railgun specifically designed for injection of high-velocity hydrogen pellets was constructed and tested. Hydrogen pellets were first accelerated to medium velocities (∼ 500 m/s) using a gas gun and then injected into the railgun. Once a pellet entered the railgun, a plasma arc was initiated by electrically breaking down the propellant gas which followed the pellet from the gas gun into the railgun. Utilizing the propulsive force of this plasma arc armature, further acceleration of the hydrogen pellet was achieved. Using a 60 cm long railgun, proof-of-principle experiments were performed on hydrogen pellets, 1.6 mm, in diameter and 2.15 mm in length, producing velocities exceeding 1.5 km/s. Encouraged by this preliminary success, more extensive studies are in progress to further improve the performance and capabilities of the current system

  7. MULTIPARTICULATE DRUG DELIVERY SYSTEM: PELLETIZATION THROUGH EXTRUSION AND SPHERONIZATION

    Anshuli Sharma

    2013-02-01

    Full Text Available Pharmaceutical invention and research are increasingly focusing on delivery systems which enhance desirable therapeutic objectives while minimising side effects. Recent trends indicate that multiparticulate drug delivery systems are especially suitable for achieving controlled or delayed release oral formulations with low risk of dose dumping, flexibility of blending to attain different release patterns as well as reproducible and short gastric residence time. Pelletization is a technique used to prepare fine powders into pellets used as multiparticulate drug delivery systems. There are different pelletization techniques used to prepare pellets. Extrusion and spheronization is one of them used to prepare pellets drug loaded beads/pellets for extended release or sustained release oral formulations such as tablets and capsules.

  8. Application of Pellet Injection to Mitigate Transient Events in ITER

    Baylor, Larry

    2015-11-01

    The injection of cryogenic pellets has been shown to be useful for mitigation of ELMs and disruptions, which are potentially damaging transient events that can to lead to reduced operating time in ITER. The triggering of small ELMs by pellets has been demonstrated as a method to prevent large ELMs that can erode plasma facing components. D2 pellets 25mm in size of neon, argon, and D2 mixtures are planned to mitigate disruptions. Shattered pellets have been shown to successfully mitigate thermal and current quenches in DIII-D with higher assimilation than massive gas injection. A flexible multi-barrel system for shattered pellet injection is now being designed for disruption mitigation in ITER. The technology and the physics of the pellet plasma interactions for these systems on ITER will be discussed. This work supported by the Oak Ridge National Laboratory, managed by UT-Battelle, LLC for the US DOE under DE-AC05-00OR22725.

  9. Microstability analysis of pellet fuelled discharges in MAST

    Garzotti, L; Roach, C M; Valovic, M; Dickinson, D; Naylor, G; Romanelli, M; Scannell, R; Szepesi, G

    2014-01-01

    Reactor grade plasmas are likely to be fuelled by pellet injection. This technique transiently perturbs the profiles, driving the density profile hollow and flattening the edge temperature profile. After the pellet perturbation, the density and temperature profiles relax towards their quasi-steady-state shape. Microinstabilities influence plasma confinement and will play a role in determining the evolution of the profiles in pellet fuelled plasmas. In this paper we present the microstability analysis of pellet fuelled H-mode MAST plasmas. Taking advantage of the unique capabilities of the MAST Thomson scattering system and the possibility of synchronizing the eight lasers with the pellet injection, we were able to measure the evolution of the post-pellet electron density and temperature profiles with high temporal and spatial resolution. These profiles, together with ion temperature profiles measured using a charge exchange diagnostic, were used to produce equilibria suitable for microstability analysis of th...

  10. Portuguese pellets market: Analysis of the production and utilization constrains

    As opposite in Portugal, the wood pellets market is booming in Europe. In this work, possible reasons for this market behavior are foreseen according to the key indicators of biomass availability, costs and legal framework. Two major constrains are found in the Portuguese pellets market: the first one is the lack of an internal consumption, being the market based on exportations. The second one is the shortage of raw material mainly due to the competition with the biomass power plants. Therefore, the combination of the biomass power plants with pellet production plants seems to be the best option for the pellets production in the actual Portuguese scenario. The main constrains for pellets market has been to convince small-scale customers that pellets are a good alternative fuel, mainly due to the investment needed and the strong competition with natural gas. Besides some benefits in the acquisition of new equipment for renewable energy, they are insufficient to cover the huge discrepancy of the investment in pellets heating. However, pellets are already economic interesting for large utilizations. In order cover a large amount of households, additional public support is needed to cover the supplementary costs of the pellets heating systems. - Highlights: ► There is a lack of internal consumption being the pellets market based on exportation. ► The shortage of raw material is mainly due to the biomass power plants. ► Combining pellet plants with biomass power plants seems to be a wise solution. ► The tax benefits of renewable energy equipments are not enough to cover the higher investment. ► Pellets are already economic interesting for large utilizations in the Portuguese scenario.

  11. In vivo cellular uptake of bismuth ions from shotgun pellets

    Stoltenberg, M; Locht, L.; Larsen, Agnete; Jensen, D.

    2003-01-01

    Shotgun pellets containing bismuth (Bi) are widely used and may cause a rather intense exposure of some wild animals to Bi. A Bi shotgun pellet was implanted intramuscularly in the triceps surae muscle of 18 adult male Wistar rats. Another group of 9 animals had a Bi shotgun pellet implanted intracranially in the neocortex. Eight weeks to 12 months later the release of Bi ions was analysed by autometallography (AMG) of tissue sections from different organs (bra...

  12. Oxidation and pulverization of UO2 and MOX pellets

    Accidents in plutonium processing plants due to the combustion of kerosene may involve the oxidation and pulverization of nuclear fuel pellets. Hence, some simulation experiments were performed in a glove box to study the behaviour of pellets of different composition (UO2/PuO2, i.e. MOX) and preparation conditions (sintered or green pellets with or without binding agent) as a function of temperature, time and oxidation atmosphere, especially in relation to the formation of coarse and respirable particles. (orig.)

  13. Methods of Nitrogen Oxide Reduction in Pellet Boilers

    Žandeckis, A; Blumberga, D; Rochas, C.; Veidenbergs, I; Siliņš, K

    2010-01-01

    The main goal of this research was to create and test technical solutions that reduce nitrogen oxide emissions in low-capacity pellet boiler. During the research, wood pellets were incinerated in a pellet boiler produced in Latvia with a rated capacity of 15 kW. During the research two NOx emission reduction methods were tested: secondary air supply in the chamber and recirculation of flue gases. Results indicated a drop of NOx concentration only for flue gas recirculation methods. Maximum re...

  14. Issues connected with SBS PCM based self-navigation of laser drivers on injected pellets

    its final high power pellet irradiation. This is a completely passive system having its optical components appropriately designed for every individual channel taking advantage of their index of refraction dependence on the wavelength. In comparison with the earlier design, an upgraded scheme was developed with the low energy illumination laser beam entering the reactor chamber through the same entrance window as used by the corresponding high energy irradiation laser beam. The pellet survival conditions in the period between its low energy illumination and subsequent high energy irradiation were studied and the upper limits on the allowed energies absorbed for both DD and DT fuels were found. Results of experimental verification of this improved design will be reported. In these experiments for the first time a complete setup including the pellet (realized by the static steel ball) was employed. Issues of the pellets with cones and parasitic effects of perpendicular SBS will be also discussed. Acknowledgements. This research was supported by International Atomic Energy Agency Research Contracts No. 13781 and 13758.

  15. Fuel compliance model for pellet-cladding mechanical interaction

    This paper describes two aspects of fuel pellet deformation that play significant roles in determining maximum cladding hoop strains during pellet-cladding mechanical interaction: compliance of fragmented fuel pellets and influence of the pellet end-face design on the transmission of axial compressive force in the fuel stack. The latter aspect affects cladding ridge formation and explains several related observations that cannot be explained by the hourglassing model. An empirical model, called the fuel compliance model and representing the above aspects of fuel deformation, has been developed using the results from two Halden experiments and incorporated into the FRAP-T6 fuel performance code

  16. Depth profiling of irradiated alanine-polymer pellets

    An alanine-polyethylene (PE) pellet is used as an alanine/electron spin resonance (ESR) dosimeter in radiation facilities. Using the unique depth profiling capability of Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS), the chemical structure of the alanine-PE pellet and its fading reaction after γ-ray irradiation have been studied. It was found that PE concentration of the alanine-PE pellet in a surface or near surface is larger that in a bulk. The products resulting from fading were observed in the bulk alanine-PE pellet irradiated and stored for 6 months at room temperature. (author)

  17. A standard procedure for measuring pellet hardness of rodent diets.

    Thigpen, J E; Locklear, J; Romines, C; Taylor, K A; Yearby, W; Stokes, W S

    1993-10-01

    A Chatillon Model TCM-200 test stand with exchangeable flat horizontal or concave receptacle bases and a DFI-200 gauge load cell with multiple types of upper exchangeable test jaws (large round-flat, medium round-flat, chisel, bullet, and cone-shaped) were compared by using preautoclaved and autoclaved NIH-31 rodent diet pellets to determine which type of hardness testing system would give the most accurate and reproducible results for measuring pellet hardness. The type and size of the contact area of the upper jaws significantly affected the force required to break the pellets. Significant differences were observed between the flat-horizontal and concave receptacle bases in the force required to break the pellets when using the two round-flat upper jaws. In contrast, similar results were obtained with both bases when the bullet, chisel, or cone-shaped upper jaws were used. Autoclaved pellets were 69.4% (range, 49 to 94%) harder than preautoclaved pellets. These results suggest that different testing systems can be used for measuring pellet hardness and that a standard procedure must be used in order to compare pellet hardness results between different testing laboratories. It was concluded that the flat-horizontal base and the larger round-flat end upper jaw gave the most reproducible results for measuring pellet hardness. PMID:8277732

  18. Pellet X-ray spectra for laser fusion reactor designs

    The calculated X-ray energy contents, spectra and pulse lengths for a range of simple target designs that include deuterium-tritium fuel surrounded by mercury are given. The calculations start with a compressed pellet core at the time of ignition and the evolution of the burning pellet is followed by using a plasma hydrodynamic-thermonuclear burn-radiative transfer computer code. It is shown that the pellet-released radiation energy contents, spectra and pulse lengths depend upon pellet mass, density and material structure, and total yield. (author)

  19. Characteristics of an electron-beam rocket pellet accelerator

    An electron-beam rocket pellet accelerator has been designed, built, assembled, and tested as a proof-of-principle (POP) apparatus. The main goal of accelerators based on this concept is to use intense electron-beam heating and ablation of a hydrogen propellant stick to accelerate deuterium and/or tritium pellets to ultrahigh speeds (10 to 20 km/s) for plasma fueling of next-generation fusion devices such as the International Thermonuclear Engineering Reactor (ITER). The POP apparatus is described and initial results of pellet acceleration experiments are presented. Conceptual ultrahigh-speed pellet accelerators are discussed. 14 refs., 8 figs

  20. Characteristics of an electron-beam rocket pellet accelerator

    Tsai, C.C.; Foster, C.A.; Schechter, D.E.

    1989-01-01

    An electron-beam rocket pellet accelerator has been designed, built, assembled, and tested as a proof-of-principle (POP) apparatus. The main goal of accelerators based on this concept is to use intense electron-beam heating and ablation of a hydrogen propellant stick to accelerate deuterium and/or tritium pellets to ultrahigh speeds (10 to 20 km/s) for plasma fueling of next-generation fusion devices such as the International Thermonuclear Engineering Reactor (ITER). The POP apparatus is described and initial results of pellet acceleration experiments are presented. Conceptual ultrahigh-speed pellet accelerators are discussed. 14 refs., 8 figs.

  1. Status of the JET high frequency pellet injector

    Highlights: ► JET pellet injection system operational for plasma fuelling and ELM pacing. ► Good reliability of the system for Low Field Side injection of fuelling size pellets. ► ELM triggered by small pellets at up to 4.5 times the intrinsic ELM frequency. ► Pellet parameters range leading to a high probability to trigger ELM identified. -- Abstract: A new high frequency pellet injector, part of the JET programme in support of ITER, has been installed on JET at the end of 2007. Its main objective is the mitigation of the Edge Localized Modes (ELMs), responsible for unacceptable thermal loads on the wall when their amplitude is too high. The injector was also required to have the capability to inject pellets for plasma fuelling. To reach this double goal, the injector has to be capable to produce and accelerate either small pellets to trigger ELMs (pace making), allowing to control their frequency and thus their amplitude, or large pellets to fuel the plasma. Operational since the beginning of the 2009 JET experimental campaign, the injector, based on the screw extruder technology, suffered from a general degradation of its performance linked to extrusion instability. After modifications of the nozzle assembly, re-commissioning on plasma has been undertaken during the first half of 2012 and successful pellet ELM pacing was achieved, rising the intrinsic ELM frequency up to 4.5 times

  2. EFFECT OF POLYMERS ON DISSOLUTION PROFILE OF VENLAFAXINE HYDROCHLORIDE PELLETS

    Devarajan Krishnarajan

    2012-11-01

    Full Text Available The present invention concerns with the development of modified release capsules of Venlafaxine hydrochloride which are designed to modify the drug release by sustained release action.The present study was carried out by advanced pelletization technique. Sustained release capsules of Venlafaxine hydrochloride were formulated by using the pelletization process by drug layering on inert sugar pellets by using sucrose and Hypermellose 606 as a binder. The drug layered pellets were coated by using the HPMC, CMC & with Eudragit grades as a coating material, P.E.G-6000 as a plasticizer, aerosil and magnesium stearate as a glidant & Isopropyl alcohol and water used as solvent materials to sustain the drug release.Formulation of venlafaxine hydrochloride pellets has been done by two stages drug loading and coating. Loading of pellets has been done by coating pan method and the coating has been done by FBC. The coated pellets size and shape is observed during processing.The coated pellets is filled in capsules size no.2 and these pellets were evaluated for appearance ,angle of repose, compressibility, Hausner’s ratio, Friability test, sieve analysis disintegration and dissolution test were performed & capsules were also evaluated for assay, weight variation, content uniformity, disintegration and in-vitro dissolution tests and observed & they are within range. There is no physicochemical interaction between drug and excipient's.

  3. Entrapment of Andrographolide in Cross- Linked Aliginate Pellets: II. Physicochemical Characterization to Study the Pelletization of Andrographolide

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

    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, Co...

  4. Fuel pellets from biomass - Processing, bonding, raw materials

    Stelte, W.

    2011-12-15

    The present study investigates several important aspects of biomass pelletization. Seven individual studies have been conducted and linked together, in order to push forward the research frontier of biomass pelletization processes. The first study was to investigate influence of the different processing parameters on the pressure built up in the press channel of a pellet mill. It showed that the major factor was the press channel length as well as temperature, moisture content, particle size and extractive content. Furthermore, extractive migration to the pellet surface at an elevated temperature played an important role. The second study presented a method of how key processing parameters can be estimated, based on a pellet model and a small number of fast and simple laboratory trials using a single pellet press. The third study investigated the bonding mechanisms within a biomass pellet, which indicate that different mechanisms are involved depending on biomass type and pelletizing conditions. Interpenetration of polymer chains and close intermolecular distance resulting in better secondary bonding were assumed to be the key factors for high mechanical properties of the formed pellets. The outcome of this study resulted in study four and five investigating the role of lignin glass transition for biomass pelletization. It was demonstrated that the softening temperature of lignin was dependent on species and moisture content. In typical processing conditions and at 8% (wt) moisture content, transitions were identified to be at approximately 53-63 deg. C for wheat straw and about 91 deg. C for spruce lignin. Furthermore, the effects of wheat straw extractives on the pelletizing properties and pellet stability were investigated. The sixth and seventh study applied the developed methodology to test the pelletizing properties of thermally pre-treated (torrefied) biomass from spruce and wheat straw. The results indicated that high torrefaction temperatures above 275 deg

  5. Indian single pellet injection system for plasma fuelling studies

    A single barrel hydrogen pellet injection system is developed at Institute for Plasma Research (IPR), India. The injector is able to produce 1.6 mm length × 1.8 mm diameter pellets. The achieved velocity of pellet is in the range of 700 to 900 m/s and is controlled by regulating the propellant pressure. The size and speed of pellet are decided by considering the neutral gas shielding model (NGS) based calculations. The injector is an in-situ pipe gun type injector, in which, a solid hydrogen pellet is formed at the freezing zone maintained at a temperature < 10 K and is accelerated to high speed using high pressure propellant gas. A GM cycle based cryocooler is used to maintain temperature at freezing zone. Proper care has been taken to minimize heat load on freezing zon using MLI. Pellet formed at the freezing zone is dislodged and accelerated to higher speed by using high pressure helium propellant gas through a fast opening valve of (opening duration < 2 millisecond). A three-stage differential pumping system is employed to remove propellant gas from injection line. Appropriate diagnostics is used to measure pellet parameters. Speed of pellet is measured by time of flight measurement using light gate diagnostic system. Pellet quality and its size, and also speed are measured using fast camera based imaging system. A Labview based GUI is used to communicate between control system and Pellet injector. The reliability of pellet formation and injection in present experimental system is greater than 95 %. (author)

  6. Casimir force in absorbing multilayers

    Tomas, M. S.

    2002-01-01

    The Casimir effect in a dispersive and absorbing multilayered system is considered adopting the (net) vacuum-field pressure point of view to the Casimir force. Using the properties of the macroscopic field operators appropriate for absorbing systems and a convenient compact form of the Green function for a multilayer, a straightforward and transparent derivation of the Casimir force in a lossless layer of an otherwise absorbing multilayer is presented. The resulting expression in terms of the...

  7. Energy-absorbing effectiveness factor

    Jones, Norman

    2010-01-01

    Abstract A study is reported on the energy-absorbing effectiveness factor which was introduced recently. The factor is defined as the quotient of the total energy, which can be absorbed in a system, to the maximum energy up to failure in a normal tensile specimen, which is made from the same volume of material. This dimensionless parameter allows comparisons to be made of the effectiveness of various geometrical shapes and of energy-absorbers made from different materials. The infl...

  8. Simultaneos determination of absorbed doses due to beta and gamma radiations with CaSO4: Dy produced at Ipen

    Due to the Goiania radiological accident, it was necessary to develop urgently a dosimeter in order to evaluate, simultaneously, beta and gamma absorbed doses, due to 137Cs radiations. Therefore, the Dosimetric Material Production Laboratory of IPEN developed a simple, practical, light and low cost badge using small thickness (0,20mm) thermoluminescent CaSO4: Dy pellets produced by the same laboratory. This pellets are adequate for beta radiation detection. These dosimeters were worn by some IPEN technicians who worked in Goiania city, and were used to evaluate the external and internal contaminations presented by the accident victims interned at the Hospital Naval Marcilio Dias. (author)

  9. The current profile modification in JT-60 pellet injection experiments

    The current profile modification by the pellet injection has been numerically investigated on JT-60 Tokamak using the diffusion equation of the poloidal magnetic field. The results suggests q(0)<1 during the sawtooth-free phase obtained by high power NB heating of pellet injected plasmas. (author)

  10. Experimental study of curved guide tubes for pellet injection

    The use of curved guide tubes for transporting frozen hydrogen pellets offers great flexibility for pellet injection into plasma devices. While this technique has been previously employed, an increased interest in its applicability has been generated with the recent ASDEX Upgrade experimental data for magnetic high-field side (HFS) pellet injection. In these innovative experiments, the pellet penetration appeared to be significantly deeper than for the standard magnetic low-field side injection scheme, along with corresponding greater fueling efficiencies. Thus, some of the major experimental fusion devices are planning experiments with HFS pellet injection. Because of the complex geometries of experimental fusion devices, installations with multiple curved guide tube sections will be required for HFS pellet injection. To more thoroughly understand and document the capability of curved guide tubes, an experimental study is under way at the Oak Ridge National Laboratory (ORNL). In particular, configurations and pellet parameters applicable for the DIII-D tokamak and the International Thermonuclear Experimental Reactor (ITER) were simulated in laboratory experiments. Initial test results with nominal 2.7- and 10-mm-diam deuterium pellets are presented and discussed

  11. Automatic defect identification on PWR nuclear power station fuel pellets

    This article presents a new automatic identification technique of structural failures in nuclear green fuel pellet. This technique was developed to identify failures occurred during the fabrication process. It is based on a smart image analysis technique for automatic identification of the failures on uranium oxide pellets used as fuel in PWR nuclear power stations. In order to achieve this goal, an artificial neural network (ANN) has been trained and validated from image histograms of pellets containing examples not only from normal pellets (flawless), but from defective pellets as well (with the main flaws normally found during the manufacturing process). Based on this technique, a new automatic identification system of flaws on nuclear fuel element pellets, composed by the association of image pre-processing and intelligent, will be developed and implemented on the Brazilian nuclear fuel production industry. Based on the theoretical performance of the technology proposed and presented in this article, it is believed that this new system, NuFAS (Nuclear Fuel Pellets Failures Automatic Identification Neural System) will be able to identify structural failures in nuclear fuel pellets with virtually zero error margins. After implemented, the NuFAS will add value to control quality process of the national production of the nuclear fuel.

  12. Ablation of Hydrogen Pellets in Hydrogen and Helium Plasmas

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

    1975-01-01

    Measurements on the interaction between solid hydrogen pellets and rotating plasmas are reported. The investigations were carried out because of the possibility of refuelling fusion reactors by the injection of pellets. The ablation rate found is higher than expected on the basis of a theory...

  13. Numerical analysis of the influence of the fuel pellet shape on the pellet-cladding contact condition

    One of the problems of greater concern in nuclear fuels operation is that of pellet-cladding interaction (PCI), since it may be cause of fuel failure. In unfailed claddings, the occurrence of contact with the pellet is generally evidenced by a typical deformation pattern known as bamboo effect. In the present work different pellets' shapes are proposed, all of them with a chamfer next to the top and bottom surfaces. The performance of these pellets design is simulated with a numerical code, DIONISIO, previously developed in this working group, which makes use of the finite elements method. It provides the temperature, stress and strain distribution and the inventory of fission gases by analyzing phenomena like thermal expansion, elasticity, plasticity, creep, irradiation growth, PCI, swelling and densification. The pellets' design tested are grouped into two types: those with a straight chamfer running from the central pellet plane to both extremes (R-type pellets) and those with the chamfer occupying one quarter of the pellet's height leaving a central ring of the standard, cylindrical shape (M-type pellets). Different chamfer depths were numerically tested. It was found that the gap increase associated with the introduction of a deep chamfer is responsible for a significant temperature increment. But chamfers which leave a gap of 110 to 150 μm (assuming a normal fuel element with a gap 90 μm thick) gave place to pellets with an adequate thermal response and, moreover, the disappearance of the bamboo effect or even the appearance of an inverse effect, that is, pellets which make contact with the cladding in the region around its middle plane. (author)

  14. Advanced Doped UO2 Pellets in LWR Applications

    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) UO2 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 UO2 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 UO2 pellets are small. 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 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 30 MWd/kgU in a commercial BWR. ADOPT reveals up to 50% lower fission gas release than standard UO2 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

  15. A pellet tracking system for hadron physics experiments

    Pyszniak A.

    2014-03-01

    Full Text Available Frozen microspheres of hydrogen (pellets are used as targets in the hadron physics experiment WASA (Forschungszentrum Jülich, Germany [1] and will also be used in the future PANDA experiment at FAIR (GSI, Darmstadt, Germany [2]. The interaction region is defined by the overlap of the pellet stream and the accelerator beam and has a size of a few millimeters. One would like to know the interaction point more precisely, to have better possibility to reconstruct particle tracks and events. One would also like to suppress background events that do not originate in a pellet, but e.g. may occur in residual gas in the beam pipe. A solution is provided by the presented pellet tracking system, for which a prototype [3] has been developed in Uppsala. The goal is to track individual pellets in order to know their position at the time of an interaction. The design of such a system, simulation techniques and results are presented.

  16. Method for sampling nuclear fuel pellets with a robot gripper

    This patent describes a method of gently burrowing angularly displaced gripping fingers into a stack of nuclear fuel pellets and grasping a pellet located at a predetermined depth in the stack. It comprises: lowering the fingers into the stack of pellets toward the predetermined depth therein; rotating the fingers in a first direction relative to the stack and at a first predetermined speed concurrently as the fingers are being lowered into the stack; pausing the lowering of the fingers; rotating the fingers in a second direction opposite to the first direction relative to the stack and at a second predetermined speed faster than the first speed concurrently as the fingers are paused; repeating first four steps until the desired predetermined depth is reached; and closing the fingers upon reaching the predetermined depth to grasp a pellet located at the depth in the stack of pellets

  17. Calculation of density profiles in tandem mirrors fueled by pellets

    We have modified the LLNL radial transport code TMT to model reactor regime plasmas, fueled by pellets. The source profiles arising from pellet fueling are obtained from existing pellet ablation models. Because inward radial diffusion due to inverted profiles must compete with trapping of central cell ions in the transition region for tandem mirrors, pellets must penetrate fairly far into the plasma. In fact, based on our radial calculations, a pellet with a velocity of 10 km/sec cannot sustain the central flux tubes; a velocity more like 100 km/sec will be necessary. We also find that the central cell radial diffusion must exceed classical by about a factor of 100

  18. Straw pellets as fuel in biomass combustion units

    Andreasen, P.; Larsen, M.G. [Danish Technological Inst., Aarhus (Denmark)

    1996-12-31

    In order to estimate the suitability of straw pellets as fuel in small combustion units, the Danish Technological Institute accomplished a project including a number of combustion tests in the energy laboratory. The project was part of the effort to reduce the use of fuel oil. The aim of the project was primarily to test straw pellets in small combustion units, including the following: ash/slag conditions when burning straw pellets; emission conditions; other operational consequences; and necessary work performance when using straw pellets. Five types of straw and wood pellets made with different binders and antislag agents were tested as fuel in five different types of boilers in test firings at 50% and 100% nominal boiler output.

  19. Method for solidification and disposal of radioactive pellet waste

    Object: To form radioactive waste into pellet, which is impregnated with plastic monomer for polymerization, and then packed into a drum can to have gaps between composites filled with cement, mortar, and molten asphalt, thus increasing water resistance and strength. Structure: Radioactive powdery bodies discharged from a thin film scaraping drier are formed into pellets in the desired shape. The thus pelletized radioactive solid waste is impregnated with a fluid plastic monomer such as styrene monomer and methacrylacidmethyl, and a polymerization accelerator is added thereto for polymerization. As a consequence, a composite pellet of powdery solid waste and plastic may be obtained. This is packed into the drum can container, into which cement paste, cement mortar or molten asphalt are put to fill the space between the plastic pellet composites, thus obtaining a solidified body integral with the drum can. (Taniai, N.)

  20. Finite Element Modeling of Pellet-Clat Mechanical Interaction

    Pellet-clad interaction is one of the operational problems encountered in nuclear industry. Failure of fuel elements due to pellet-clad interactions in a significant release of radioactivity to coolant. This in turn may be cause more serious safety problems. Nuclear industry is seeking solution to avoid such problems. On the other hand mechanisms for the development of pellet-clad interactions are not well understood. In this study, mechanical part of pellet-clad interaction is analyzed with a simple model based on finite element analysis. General Electric BWR/6 fuel element is used to provide model parameters. Coupled thermal and mechanical analyses of fuel element are performed using a general purpose finite element software ANSYS. In the model, pellet-clad interactions are created by considering certain contact points with various sizes. local parameters such as temperature, strain, and stress are calculated. Results are used to make an essessment of operational conditions

  1. Ablation of hydrogen ice pellet in JT-60 plasma

    Ablation of hydrogen ice pellet in the JT-60 plasma was calculated by ORNL pellet ablation code, which employs a neutral gas shielding model. An optimum scheme to produce central peaked ne profile of ne(O) = 2 X 10∼3 and ne(O)/e> ∼ 3 in the ohmic discharge appears to be a pellet injection with the pellet size of 3.4 mm diameter and velocity of 2 km/s. Under the assumption of electron heat diffusivity Xe = 2 x 1019/ne (m2/s), the 1-D tokamak code (LIBRARY) predicts ∼ 30 % increment of fusion multiplication (Q) for pellet fueled peaked density profile compared with gas fueled discharge. (author)

  2. Upgrade of JT-60 pellet injector for higher velocity

    Pellet injection experiments have been performed to improve the plasma performance by the JT-60 tokamak from June, 1988. From the results of the experiments, it was found that the plasma confinement time increased up to 40% with pellet injection (velocity over 1.5 km/s), in which was obtained with 10 MW neutral beam injection highly peaked electron density profile. The experimental results suggested that improvement of the plasma confinement time depends on the penetration depth of the pellet into the plasma column, especially into 'q2 to 100 kg/cm2 and from 80degC to 200degC respectively. The upgraded pellet injector can inject, independently, four pellets, two of which are 3.0 mm in diameter x 3.0 mm in length and the other two of which are 4.0 mm in diameter x 4.0 mm in length. (author)

  3. Improved pellet charge exchange measurements in Large Helical Device

    The pellet charge exchange technique (PCX), which is a combination of the compact neutral particle analyzer and an impurity pellet, is a unique method to observe the radial energetic particle distribution. There are not only charge exchange reactions between the hydrogen in the pellet and a proton, but also between the partially ionized carbon in the pellet and the proton. The neutralization factor from energetic ion to neutral particle could be deduced from the electron temperature and the electron density of the pellet cloud. The radial profiles of energetic particle distribution were measured and compared in various ion cyclotron resonance heating (ICH) plasmas. The energetic particle flux significantly increased at the resonance layer created by the ICH. PCX provides more precise information about the resonance layer than conventional neutral particle diagnostics. (author)

  4. ["Piggyback" shot: ballistic parameters of two simultaneously discharged airgun pellets].

    Frank, Matthias; Schönekess, Holger C; Grossjohann, Rico; Ekkernkamp, Axel; Bockholdt, Britta

    2014-01-01

    Green and Good reported an uncommon case of homicide committed with an air rifle in 1982 (Am. J. Forensic Med. Pathol. 3: 361-365). The fatal wound was unusual in that two airgun pellets were loaded in so-called "piggyback" fashion into a single shot air rifle. Lack of further information on the ballistic characteristics of two airgun pellets as opposed to one conventionally loaded projectile led to this investigation. The mean kinetic energy (E) of the two pellets discharged in "piggyback" fashion was E = 3.6 J and E = 3.4 J, respectively. In comparison, average kinetic energy values of E = 12.5 J were calculated for conventionally discharged single diabolo pellets. Test shots into ballistic soap confirmed the findings of a single entrance wound as reported by Green and Good. While the ballistic background of pellets discharged in "piggyback" fashion could be clarified, the reason behind this mode of shooting remains unclear. PMID:24855739

  5. Energy absorber for the CETA

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  6. Energy absorber for the CETA

    Wesselski, Clarence J.

    1994-05-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  7. Leaf absorbance and photosynthesis

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  8. Tritium pellet injector for the Tokamak Fusion Test Reactor

    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) plasma phase. An existing deuterium pellet injector (DPI) was 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 for frozen pellets ranging in size from 3 to 4 mm in diameter in arbitrarily programmable firing sequences at tritium pellet 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 (PLC). The new pipe-gun injector assembly was installed in the modified DPI guard vacuum box, and modifications were also 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 pellets. Results of the testing program at ORNL are described. The TPI has been installed and operated on TFTR in support of the CY-92 deuterium plasma run period. In 1993, the tritium pellet injector will be retrofitted with a D-T fuel manifold and tritium gloveboxes and integrated into TFTR tritium processing systems to provide full tritium pellet capability

  9. Emissions from small scale combustion of pelletized wood fuels

    Combustion of wood pellets in small scale heating systems with an effect below 20 kW has increased. During the winter season 1995/96 1500 small plants for heating houses are estimated to be in operation. Stack emissions from three pellet burners and two pellet stoves have been studied at laboratory. Different pellet qualities were tested. When the fraction of fines increased also the NOx emissions increased with about 10 %. As reference fuel 8 mm pellets was used. Tests with 6 mm pellets gave, in most cases, significant lower emissions of CO and THC. Eleven stoves, burners and boilers were studied in a field test. The results show that all the plants generally have higher emissions in the field than during conditions when the plants are adjusted with a stack gas monitoring instrument. A conclusion is that it is difficult for the operator to adjust the plant without a monitoring instrument. The emissions from the tested plants give an estimation of stack gas emissions from small scale pellet plants. The difference between the 'best' and 'worst' technologies is big. The span of emissions with the best technology to the worst is given below. The interval is concerning normal combustion . During abnormal conditions the emissions are on a significant higher level: * CO 80-1 000 mg/MJ; * Tar 0,3-19 mg/MJ; * THC (as methane equivalents) 2-100 mg/MJ; * NOx 50-70 mg/W;, and * Dust emissions 20-40 mg/MJ. Emissions from pellets heating are lower than from wood combustion and the best technology is close to the emission from oil burners. Wood and pellets have the same origin but the conditions to burn them in an environmental friendly way differ. Combustion of pellets could be improved through improved control of the air and fuel ratio that will create more stable conditions for the combustion

  10. Dissolution experiments of unirradiated uranium dioxide pellets

    The purpose of this study was to measure the dissolution rate of uranium from unirradiated uranium dioxide pellets in deionized water and natural groundwater. Moreover, the solubility limit of uranium in natural groundwater was measured. Two different temperatures, 25 and 60 deg C were used. The low oxygen content of deep groundwater was simulated. The dissolution rate of uranium varied from 10-7 to 10-8 g cm-2 d-1. The rate in reionized water was one order of magnitude lower than in groundwater. No great difference was observed between the natural groundwaters with different composition. Temperature seems to have effect on the dissolution rate. The solubility limit of uranium in natural groundwater in reducing conditions, at 25 deg C, varied from 20 to 600 μg/l and in oxidizing conditions, at 60 deg C, from 4 to 17 mg/l