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

    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.

  14. 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

  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. 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...

  2. 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.

  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. 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)

  1. 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.)

  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. 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

  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. 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.)

  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. 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)

  13. 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)

  14. 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...

  15. 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)

  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. 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.

  18. 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.

  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. 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)

  1. 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

  2. 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

  3. 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.

  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. 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.)

  6. 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.)

  7. 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.

  8. 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...

  9. 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.)

  10. 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...

  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...

  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. 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...

  14. 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)

  15. 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

  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. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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.

  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. 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.)

  13. 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

  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. 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...

  19. 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)

  20. 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...

  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

    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.

  3. 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

  4. 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

  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. 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)

  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. 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)

  15. 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...

  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. 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.).

  20. 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

  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. 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.

  8. 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

  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. 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

  16. 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)

  17. 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)

  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. 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

  20. 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.

  1. 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

  2. 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...

  3. 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}.

  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. 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.

  6. 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

  7. 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)

  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. 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.

  15. 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

  16. 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

  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. 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

  7. 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

  8. 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)

  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. 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)

  12. 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)

  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. 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

  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. 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.

  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. 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

  5. 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.

  6. 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

  7. 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

  8. 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...

  9. 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.

  10. 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.)

  11. 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...

  12. 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.

  13. 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...

  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. 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)

  16. 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

  17. 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)

  18. 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

  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. 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...

  7. 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...

  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. 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

  16. 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.

  17. 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

  18. 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

  19. 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)

  20. 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.

  1. 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)

  2. 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)

  3. 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.)

  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.

    1994-05-01

    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.

  6. 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.

  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

  11. Confirmation methods of radioactive wastes of the type of pellet-granule and pellet solid

    In Japan, low-level radioactive wastes generated from the nuclear power plants are packed into 200-litter drums and conveyed and stored at the underground disposal facility of Rokkasho Nuclear Fuel Reprocessing Plant. The waste drums generally contain homogeneously solidified waste materials which have been prepared from concentrated radionuclide solutions by adding cement, asphalt, or plastics. Before disposal the content must be confirmed and checked up according to the authorized standardization and disposal criteria. The present report describes some guidelines for the case of waste type of pellet-granule and pellet solid. The confirmation method for the utility of Scaling Factors is discussed and described on the ground of investigation at the technical task committee. (S. Ohno)

  12. Review: study of single-pellet injection experiments and development of pellet injector in JFT-2M

    The single pellet injector developed for JFT-2M and the improvement of plasma characteristics in the auxiliary-heated discharges by single-pellet injection are reviewed for the period 1982 - 1986. The pellet injector is a pneumatic type and the designed pellet size is 1.65 mmD x 1.65 mmL and 1 mmD x 1 mmL. The hydrogen, deuterium and mixed (H2 + D2) pellets can be produced with good reproducibility. Maximum pellet velocity is about 970 m/s (pellet is deuterium and propellant gas is hydrogen). In the pellet injection experiments into auxiliary-heated (NB, ICRF) divertor or limiter discharges, the plasma confinement time is improved by a factor of 1.4 - 1.7 compared with the confinement time in the Ohmic discharges. The achieved confinement time is longer than that on the high confinement mode (H-mode) in gas fueled discharges, although the phenomena are transient. (author)

  13. Post irradiation examination experience of hollow pellets for PWRs

    In order to increase flexibility of the reactor operation mode, a high performance fuel has ben investigated in Japan. Hollow fuel pellets are adopted as a design improvement for the mitigation of pellet cladding interaction (PCI) by decreasing the fuel pellet temperature during irradiation. The high performance 17x17 B type PWR fuel was supplied by Nuclear Fuel Industries, Ltd. (NFI) and achieved a burnup of 34.3 GWd/t after 2 cycles of irradiation under normal operating conditions in Ohi Unit 2 of the Kansai Electric Power Co. Inc. (Kansai). The irradiation test program of the high performance fuel was conducted by Nuclear Power Engineering Corporation (NUPEC) under sponsorship of the Ministry of International Trade and Industry (MITI) from 1981 to 1993. After completion of irradiation, the high performance fuel assembly was transported to the hot cell facility at Japan Energy Research Institute (JAERI) in Tokai-mura. Nondestructive and destructive examinations were performed on standard and improved fuel rods. In order to evaluate the ridging deformation, the cladding outer diameter profile of these fuel rods was measured. Ridging deformation of the hollow fuel pellets was smaller than in the standard fuel pellets. Gamma scanning was performed by measuring the total γ-ray intensity and specific nuclides' intensity. The axial distribution of the γ-ray intensity was fairly flat within the measured active region of each fuel rod. The puncture test was performed for the evaluation of fission gas release (FGR) and fuel rod internal pressure. The FGR of fuel pellets showed no significant difference between the two types of fuel pellets, but the internal pressure increase in the hollow pellet fuel rods was slightly lower than that of the standard ones. This is due to the greater free volume in the hollow pellet fuel rods as fabricated. The density change and microstructure of the hollow fuel pellets after irradiation were compared to the standard pellets. There was

  14. Numerical investigations of the WASA pellet target operation and proposal of a new technique for the PANDA pellet target

    Varentsov, Victor L., E-mail: v.varentsov@gsi.de [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, 117218 Moscow (Russian Federation)

    2011-08-01

    The conventional nozzle vibration technique of the hydrogen micro-droplet generation that is supposed to be used for internal pellet target production for the future PANDA experiment at the international FAIR facility in Darmstadtfor is described. The operation of this technique has been investigated by means of detailed computer simulations. Results of calculations for the geometry and operation conditions of the WASA pellet generator are presented and discussed. We have found that for every given pellet size, there is a set of operation parameters where the efficiency of the WASA hydrogen pellet target operation is considerably increased. Moreover, the results of presented computer simulations clearly show that the future PANDA pellet target setup can be realized with the use of much smaller (and cheaper) vacuum pumps than those used at present in the WASA hydrogen pellet target. To qualitatively improve the PANDA hydrogen pellet target performance we have proposed the use of a novel flow focusing method of Ganan-Calvo and Barreto (1997,1999) combined with the use of conventional vacuum injection capillary. Possibilities of this approach for the PANDA pellet target production have been also explored by means of computer simulations. The results of these simulations show that the use of this new approach looks very promising and in particular, there is no need here to use of expensive ultra-pure hydrogen to prevent nozzle clogging or freezing up due to impurities and it will allow simple, fast, smooth and a wide range of change of pellet sizes in accordance with requirements of different experiments at the PANDA detector. In this article we also propose and describe the idea of a new technique to break up a liquid microjet into microdroplets using a process of liquid jet evaporation under pulsed laser beam irradiation. This technique should be experimentally checked before it may be used in the design of the future PANDA pellet target setup.

  15. Numerical investigations of the WASA pellet target operation and proposal of a new technique for the PANDA pellet target

    The conventional nozzle vibration technique of the hydrogen micro-droplet generation that is supposed to be used for internal pellet target production for the future PANDA experiment at the international FAIR facility in Darmstadtfor is described. The operation of this technique has been investigated by means of detailed computer simulations. Results of calculations for the geometry and operation conditions of the WASA pellet generator are presented and discussed. We have found that for every given pellet size, there is a set of operation parameters where the efficiency of the WASA hydrogen pellet target operation is considerably increased. Moreover, the results of presented computer simulations clearly show that the future PANDA pellet target setup can be realized with the use of much smaller (and cheaper) vacuum pumps than those used at present in the WASA hydrogen pellet target. To qualitatively improve the PANDA hydrogen pellet target performance we have proposed the use of a novel flow focusing method of Ganan-Calvo and Barreto (1997,1999) combined with the use of conventional vacuum injection capillary. Possibilities of this approach for the PANDA pellet target production have been also explored by means of computer simulations. The results of these simulations show that the use of this new approach looks very promising and in particular, there is no need here to use of expensive ultra-pure hydrogen to prevent nozzle clogging or freezing up due to impurities and it will allow simple, fast, smooth and a wide range of change of pellet sizes in accordance with requirements of different experiments at the PANDA detector. In this article we also propose and describe the idea of a new technique to break up a liquid microjet into microdroplets using a process of liquid jet evaporation under pulsed laser beam irradiation. This technique should be experimentally checked before it may be used in the design of the future PANDA pellet target setup.

  16. Numerical investigations of the WASA pellet target operation and proposal of a new technique for the PANDA pellet target

    Varentsov, Victor L.

    2011-08-01

    The conventional nozzle vibration technique of the hydrogen micro-droplet generation that is supposed to be used for internal pellet target production for the future PANDA experiment at the international FAIR facility in Darmstadtfor is described. The operation of this technique has been investigated by means of detailed computer simulations. Results of calculations for the geometry and operation conditions of the WASA pellet generator are presented and discussed. We have found that for every given pellet size, there is a set of operation parameters where the efficiency of the WASA hydrogen pellet target operation is considerably increased. Moreover, the results of presented computer simulations clearly show that the future PANDA pellet target setup can be realized with the use of much smaller (and cheaper) vacuum pumps than those used at present in the WASA hydrogen pellet target. To qualitatively improve the PANDA hydrogen pellet target performance we have proposed the use of a novel flow focusing method of Gañán-Calvo and Barreto (1997,1999) [28,30] combined with the use of conventional vacuum injection capillary. Possibilities of this approach for the PANDA pellet target production have been also explored by means of computer simulations. The results of these simulations show that the use of this new approach looks very promising and in particular, there is no need here to use of expensive ultra-pure hydrogen to prevent nozzle clogging or freezing up due to impurities and it will allow simple, fast, smooth and a wide range of change of pellet sizes in accordance with requirements of different experiments at the PANDA detector. In this article we also propose and describe the idea of a new technique to break up a liquid microjet into microdroplets using a process of liquid jet evaporation under pulsed laser beam irradiation. This technique should be experimentally checked before it may be used in the design of the future PANDA pellet target setup.

  17. Hybrid pellets: an improved concept for fabrication of nuclear fuel

    The feasibility of fabricating fuel pellets using gel-derived microspheres as press feed was evaluated. By using gel-derived microspheres as press feed, the potential exists for eliminating dusty operations like milling, slugging, and granulation, from the pelleting process. The free-flowing character of the spheres should also result in limited dust generation during powder transport and pressing operations. The results of this study clearly demonstrate that fuel pellets can be successfully fabricated on a laboratory scale using UO2 gel microspheres as press feed. Under moderate sintering conditions, 1,5000C for 4 h in Ar-4% H2, UO2 pellets with densities up to 96% TD were fabricated. A range of pellet microstructures and densities were achieved depending on sphere forming and calcining conditions. Based on these results, a set of necessary sphere properties are suggested: O/U less than 2.20, crystallite size less than 500 A, specific surface area greater than 8 m2/g, and sphere size 200 and 400 μm. Preliminary attempts to fabricate ThO2 and ThO2-UO2 pellets using microspheres were unsuccessful because the requisite sphere properties were not achieved. Areas requiring additional development include: demonstration of the process on scaled-up equipment suitable for use in a remote fuel fabrication facility and evaluation of the irradiation performance of pellet fuels from gel-spheres

  18. Consolidated waste forms: glass marbles and ceramic pellets

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

  19. Consolidated waste forms: glass marbles and ceramic pellets

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

    1982-05-01

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

  20. Production and Innovative Applications of Cryogenic Solid Pellets

    For over two decades Oak Ridge National Laboratory has been developing cryogenic pellet injectors for fueling hot, magnetic fusion plasmas. Cryogenic solid pellets of all three hydrogen isotopes have been produced in a size range of 1- to 10-mm diameter and accelerated to speeds from <100 to ∼3000 m/s. The pellets have been formed discretely by cryocondensation in gun barrels and also by extrusion of cryogenic solids at mass flow rates up to ∼0.26 g/s and production rates up to ten pellets per second. The pellets traverse the hot plasma in a fraction of a millisecond and continuously ablate, providing fresh hydrogenic fuel to the interior of the plasma. From this initial application, uses of this technology have expanded to include (1) cryogenic xenon drops or solids for use as a debris-less target in a laser plasma source of X-rays for advanced lithography systems, (2) solid argon and carbon dioxide pellets for surface cleaning or decontamination, and (3) methane pellets in a liquid hydrogen bath for use as an innovative moderator of cold neutrons. Methods of production and acceleration/transport of these cryogenic solids will be described, and examples will be given of their use in prototype systems

  1. Laser driven pellet refuelling for JET (and reactor) uses

    Published estimates of pellet sizes and velocities required to refuel JET and post-JET experiments are summarized. Possible advantages and difficulties of accelerating solid, unconstrained hydrogenic (and also jacketed) pellets to these velocities using laser techniques are then discussed. An essential problem to be solved is adequate axial guidance of the pellet during its acceleration, since laser pulse durations of many sound-transit times (in the solid D2) are necessary to avoid shock-heating the pellet. It is shown that Culham's multikilojoule CO2 TROJAN laser facility is well suited to testing many of the concepts proposed. In particular it is shown that successful verification, and subsequent optimization, of such (novel) techniques would permit single shot tests of contemporary pellet ablation theories by the injection of approximately 1 mm diameter D2 pellets at velocities 6 cm s-1 into the JET plasma. Means for scaling these techniques to repetition rates of order 10 Hz, and to the 1 cm pellet diameters possibly required in a working Tokamak reactor, are also discussed. (author)

  2. Pellet-Clad Mechanical Interaction Analysis with ANSYS Mechanical Module

    Pellet-Clad Mechanical Interaction (PCMI) has been known as a potential threat in fuel cladding integrity during power ramp conditions and high burn-up scenario. As the fuel outer surface contact with clad inner surface, the local stress become increased. Moreover, fuel pellet have much higher temperature in operation and have much greater expansion effects than clad, which occur additional contact pressure on clad inner surface, the cladding pellet deforms into a shape reflecting that of the pellet. This mechanical interaction between fuel pellet and clad depends on gap size, burn-up, friction coefficient between clad and pellet. Moreover, recent field result shows that nearly PCI-induced failures are thought to have developed at a missing pellet surface (MPS), where the tangential stress has its maximum and the cladding temperature has its minimum. For the additional study on PCMI, it is very important and valuable to find geometric parameters of MPS which make critical safety issue on cladding material safety. Followings are result and conclusion of the parametric studies

  3. Liquid metal reactor absorber technology

    This paper reports that the selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth, compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts

  4. Liquid metal reactor absorber technology

    The selection of boron carbide as the reference liquid metal reactor absorber material is supported by results presented for irradiation performance, reactivity worth compatibility, and benign failure consequences. Scram response requirements are met easily with current control rod configurations. The trend in absorber design development is toward larger sized pins with fewer pins per bundle, providing economic savings and improved hydraulic characteristics. Very long-life absorber designs appear to be attainable with the application of vented pin and sodium-bonded concepts. 3 refs., 3 figs

  5. Fecal Pellet Flux in the Mesopelagic Sargasso Sea

    Koweek, D.; Shatova, O.; Conte, M. H.; Weber, J. C.

    2010-12-01

    The Oceanic Flux Program (OFP), located 75km SE of Bermuda, is the longest running sediment trap time-series of its kind, continually collecting deep sea particle flux since 1978. Recent application of digital microphotography to the size-fractionated OFP sediment trap material has generated a wealth of new quantitative visual information on particle flux composition, its changes with depth, and its temporal variability. We examined the fecal pellet flux at 1500m depth using image analysis of digital archives, in conjunction with data on the overlying surface ocean from the Bermuda Testbed Mooring (BTM) and the Bermuda Atlantic Time Series (BATS) programs, to investigate the role of mesoscale physical forcing on mesopelagic particle flux variability. During 2007, a productive cyclonic eddy, a mode water eddy and an anticyclonic eddy passed over the OFP site. Fecal pellet flux was enhanced during passage of both the cyclonic and mode water eddies. Total mass flux (TMF) was also enhanced during the productive cyclonic eddy, but was not influenced by the passage of the mode water eddy. No increase in fecal pellet flux or TMF was apparent during passage of the anticyclonic eddy despite indications of increased zooplankton abundance from ADCP backscatter intensity. Fecal pellet size frequency distributions indicate the presence of two, and sometimes three, distinct size classes. No seasonal trend in mean size of fecal pellets was observed for any size class, implying that the size distribution of the zooplankton populations producing the pellets is relatively constant throughout the year. We also investigated fecal pellet flux changes with depth at 500, 1500 and 3200m. Fecal pellet flux, and the fecal pellet contribution to TMF, were greatest at 500m and decreased with depth. The use of quantitative image analysis holds great potential as a powerful analytical tool in studies of marine particulate flux.

  6. First results on study of gadolinium as burnable absorber

    Following on with the work included in the 'Burnable absorbers research plan' several experiments were carried out oriented to determine Ga2O3 burn up. Cold tests were performed and samples were irradiated in the RA-3 reactor. In this paper, some calculated values are presented together with their comparisons with experimental ones. The parameters foreseen for performing the experiments were verified and also the predictions on burn up of uranium and gadolinium isotopes concentrations. These results imply that the nuclear data of these isotopes included in the library are satisfactory. Next steps will be to measure other isotopes concentrations, gamma spectrum, and the irradiation of one pellet to determine self shielding effects in order to obtain effective cross sections i.e. for CAREM geometry. (author)

  7. Pelleted waste form for high-level ICPP wastes

    Simulated zirconia-type calcined waste is pelletized on a 41-cm diameter disc pelletizer using 5% bentonite, 2% metakaolin, and 2% boric acid as a solid binder and 7M phosphoric plus 4M nitric acid as a liquid binder. After heat treatment at 8000C for 2 hours the pellets are impact resistant and have a leach resistance of 10-4 g/cm2 . day, based on Soxhlet leaching for 100 hours at 950C with distilled water. An integrated pilot plant is being fabricated to verify the process. 1 figure, 4 tables

  8. Nuclear fuel pellets which can be axially aligned

    The proposal concerns the shaping of nuclear fuel pellets which are applied as a fuel column, piled up one upon the other in a tube-shaped nuclear fuel can. As damages may occur at the junctions of the fuel material, if the particles are not perfectly aligned, there are made proposals according to the invention concerning the shaping of the opposite end surfaces of the nuclear fuel pellets, which are to facilitate a correct axial alignment. In 48 sub-claims and 22 drawings there is mentioned a multitude of designs which mostly have got an elevated region of convex shape in the center of the end surface of the pellet. (UA)

  9. Hyperuniformity of Critical Absorbing States

    Hexner, Daniel; Levine, Dov

    2015-03-01

    The properties of the absorbing states of nonequilibrium models belonging to the conserved directed percolation universality class are studied. We find that, at the critical point, the absorbing states are hyperuniform, exhibiting anomalously small density fluctuations. The exponent characterizing the fluctuations is measured numerically, a scaling relation to other known exponents is suggested, and a new correlation length relating to this ordering is proposed. These results may have relevance to photonic band-gap materials.

  10. The absorber hypothesis of electrodynamics

    De Luca, Jayme

    2008-01-01

    We test the absorber hypothesis of the action-at-a-distance electrodynamics for globally-bounded solutions of a finite-particle universe. We find that the absorber hypothesis forbids globally-bounded motions for a universe containing only two charged particles, otherwise the condition alone does not forbid globally-bounded motions. We discuss the implication of our results for the various forms of electrodynamics of point charges.

  11. Gas Flow Distribution in Pelletizing Shaft Furnace

    CAI Jiu-ju; DONG Hui; WANG Guo-sheng; YANG Jun

    2006-01-01

    Through thermal test, cold state experiment, analysis and simulation of thermal process, the gas flow distribution in pelletizing shaft furnace (PSF) was discussed. The results show that there are five flowing trends; among them, the downward roasting gas and the upward cooling gas are the most unsteady, which influence flow distribution greatly. Among the operating parameters, the ratio of inflow is a key factor affecting the flow distribution. The roasting and cooling gases will entirely flow into the roasting zone and internal vertical air channels (IVAC), respectively, if the ratio of inflow is critical. From such a critical operating condition increasing roasting gas flow or decreasing cooling gas flow, the roasting gas starts flowing downwards so as to enter the inside of IVAC; the greater the ratio of inflow, the larger the downward flowrate. Among constructional parameters, the width of roasting zone b1, width of IVAC b2 and width of cooling zone b3, and the height of roasting zone h1, height of soaking zone h2 and height of cooling zone h3 are the main factors affecting flow distribution. In case the ratio of b2/b1, or h3/h2, or h1/h2 is increased, the upward cooling gas tends to decrease while the downward roasting gas tends to increase with a gradual decrease in the ratio of inflow.

  12. Energetic ion diagnostics using neutron flux measurements during pellet injection

    Neutron measurements during injection of deuterium pellets into deuterium plasmas on the Tokamak Fusion Test Reactor (TFTR) indicate that the fractional increase in neutron emission about 0.5 msec after pellet injection is proportional to the fraction of beam-plasma reactions to total fusion reactions in the unperturbed plasma. These observations suggest three diagnostic applications of neutron measurements during pellet injection: (1) measurement of the beam-plasma reaction rate in deuterium plasmas for use in determining the fusion Q in an equivalent deuterium-tritium plasma, (2) measurement of the radial profile of energetic beam ions by varying the pellet size and velocity, and (3) measurement of the ''temperature'' of ions accelerated during wave heating. 18 refs., 3 figs

  13. Nuclear fuel, pellet inspection using artificial neural networks

    Nuclear fuel must be of high quality before being placed into service in a reactor. Fuel vendors currently use manual inspection for quality control of fabricated nuclear fuel pellets. In order to reduce workers' exposure to radiation and increase the inspection accuracy and speed, the feasibility of automation of fuel pellet inspection using artificial neural networks (ANNs) is studied in this paper. Three kinds of neural network architectures are examined for evaluation of the ANN performance in proper classification of good versus bad pellets. Two supervised neural networks, backpropagation and fuzzy ARTMAP, and one unsupervised neural network called ART2-A are applied. The results indicate that a supervised ANN with adequate training can achieve a high success rate in classification of fuel pellets. (orig.)

  14. Backfilling of deposition tunnels: Use of bentonite pellets

    The state of knowledge related to use of bentonite pellets as part of backfill or other gap filling components in repository applications is reviewed. How the pellets interact with adjacent sealing materials and the surrounding rock mass is a critical aspect in determining backfill behaviour. The key features and processes that determine how the pellet component of the KBS-3V deposition tunnel backfill will behave are discussed and recommendations related to what additional information needs to be developed are provided. Experiences related to pellet material composition, size, shape, placement options and more importantly, the density to which they can be placed all indicate that there are significant limitations to the achievable as-placed density of bentonite pellet fill. Low as-placed density of the pellet fill component of the backfill is potentially problematic as the outermost regions of tunnel backfill will be the first region of the backfill to be contacted by water entering the tunnels. It is also through this region that initial water movement along the length of the deposition tunnels will occur. This will greatly influence the operations in a tunnel, especially with respect to situations where water is exiting the downstream face of still open deposition tunnels. Pellet-filled regions are also sensitive to groundwater salinity, susceptible to development of piping features and subsequent mechanical erosion by through flowing water, particularly in the period preceding deposition tunnel closure. A review of the experiences of various organisations considering use of bentonite-pellet materials as part of buffer or backfill barriers is provided in this document. From this information, potential options and limitations to use of pellets or pellet-granule mixtures in backfill are identified. Of particular importance is identification of the apparent upper-limits of dry density to which such materials can to be placed in the field. These bounds will

  15. Research Progress and Development Trend of Mycelial Pellets

    Lixin Li

    2015-06-01

    Full Text Available Mycelial pellets are generated by the fermentation of microorganisms as a particle, it has good biological activity, rapid subsidence performance and simple solid-liquid separation technology, so that it can better be used in fermentation production, wastewater treatment and as biological carrier. The researches of using mycelial pellets to ferment production, treat some kinds of wastewater as biological adsorbent and enhance efficiency of treatment wastewater as bio-carrier, were discussed in detail. Development trend of mycelial pellets was presented at end of the article. It was also pointed out that the mycelial pellets as bio-carrier or biological adsorbent will be considered as a wide range of application prospects in wastewater treatment.

  16. Modeling of thermal conductivity of stainless-steelmaking dust pellets

    彭兵; 彭及; 余笛

    2004-01-01

    The thermal conductivity of stainless-steelmaking dust pellets, an important parameter for the direct recycling of the dust, is naturally of interest to metallurgists. The measurement of central temperature and surface temperature was taken in a furnace. The physical model and calculation model for the heating process were set up to check the thermal conductivity of the dust pellets. The physical structure parameters δ and λ of the basic unit are 0.92 and 0.45 based on the calculation. The temperature in the pellet can be expressed in a linear equation a5 Tp =a1 TN +a2 TM +a4. This is convenient to determine the central temperature of a pellet in the direct recycling process.

  17. UO2 fuel pellet characterization: density and porosity measurement methods

    The most commonly used fuel in nuclear power plants is UO2. UO2 is a ceramic material and is produced by powder metallurgy techniques. The densities of the material produced can never reach the theoretical densities because of the production technology. The porosity allows the gas fission products, generated under power plant working conditions, to escape and therefor is required. Direct measurement of density which is an application of the Archimedes principle, is based on replacement of liquids. Replacement fluid is m-xylene. Density measurement are made by weighing the dry pellets in air, then weighing the m-xylene impregnated pellets in air and m-xylene impregnated pellets in air and m-xylene. UO2 pellets densities, total porosities and open porosities can be calculated from the collection data

  18. Backfilling of deposition tunnels: Use of bentonite pellets

    Dixon, David (Atomic Energy of Canada Limited (Canada)); Sanden, Torbjoern (Clay Technology AB (Sweden)); Jonsson, Esther (Swedish Nuclear Fuel and Waste Mangaement Co. (Sweden)); Hansen, Johanna (Posiva Oy (Finland))

    2011-02-15

    The state of knowledge related to use of bentonite pellets as part of backfill or other gap filling components in repository applications is reviewed. How the pellets interact with adjacent sealing materials and the surrounding rock mass is a critical aspect in determining backfill behaviour. The key features and processes that determine how the pellet component of the KBS-3V deposition tunnel backfill will behave are discussed and recommendations related to what additional information needs to be developed are provided. Experiences related to pellet material composition, size, shape, placement options and more importantly, the density to which they can be placed all indicate that there are significant limitations to the achievable as-placed density of bentonite pellet fill. Low as-placed density of the pellet fill component of the backfill is potentially problematic as the outermost regions of tunnel backfill will be the first region of the backfill to be contacted by water entering the tunnels. It is also through this region that initial water movement along the length of the deposition tunnels will occur. This will greatly influence the operations in a tunnel, especially with respect to situations where water is exiting the downstream face of still open deposition tunnels. Pellet-filled regions are also sensitive to groundwater salinity, susceptible to development of piping features and subsequent mechanical erosion by through flowing water, particularly in the period preceding deposition tunnel closure. A review of the experiences of various organisations considering use of bentonite-pellet materials as part of buffer or backfill barriers is provided in this document. From this information, potential options and limitations to use of pellets or pellet-granule mixtures in backfill are identified. Of particular importance is identification of the apparent upper-limits of dry density to which such materials can to be placed in the field. These bounds will

  19. Cell Electrofusion in Centrifuged Erythrocyte Pellets Assessed by Dielectric Spectroscopy.

    Asami, Koji

    2016-04-01

    We have characterized cell electrofusion in cell pellets by dielectric spectroscopy. Cell pellets were formed from horse erythrocyte suspensions by centrifugation and were subjected to intense AC pulses. The dielectric spectra of the pellets were measured over a frequency range of 10 Hz to 10 MHz. The application of AC pulses caused low-frequency (LF) dielectric relaxation below about 100 kHz. The LF dielectric relaxation was markedly affected not only by pretreatment of cells at 50 °C, which disrupts the spectrin network of erythrocytes, but also by the parameters of the AC pulses (frequency of the sine wave and repeat count of the pulses). The occurrence of the LF dielectric relaxation was qualitatively accounted for by modeling fusion products in the pellet by prolate spheroidal cells whose long axes run parallel to the applied electric field. PMID:26407874

  20. Wall conditioning with impurity pellet injection on TFTR

    Solid lithium and boron pellets have been injected into TFTR plasmas to improve plasma performance by coating the graphite inner wall bumper limiter with a small amount of lower Z pellet material, which reduces the influx of carbon from the walls and reduces the edge electron density. This new wall conditioning technique has been applied successfully when continued He conditioning discharges, which are normally used for wall conditioning, no longer significantly reduce the carbon and deuterium influxes. The results show that both Li and B pellets significantly improve wall conditioning and lead to 15-20% improvements in supershot plasma performance when injected ≥1 s prior to neutral beam injection in supershot target plasmas. Neutral beam penetration calculations indicate that the lower edge densities resulting from Li or B pellet wall conditioning lead to improved beam penetration. Sputtering yield calculations confirm that the addition of small amounts of Li on a graphite target can significantly reduce the C sputtering yield. (orig.)

  1. Solvent-free cleaning using a centrifugal cryogenic pellet accelerator

    Haines, J.R.; Fisher, P.W.; Foster, C.A.

    1995-06-01

    An advanced centrifuge that accelerates frozen CO{sub 2} pellets to high speeds for surface cleaning and paint removal is being developed at the Oak Ridge National Laboratory. The centrifuge-based accelerator was designed, fabricated, and tested under a program sponsored by the Warner Robins Air Logistics Center, Robins Air Force Base, Georgia. In comparison to the more conventional compressed air ``sandblast`` pellet accelerators, the centrifugal accelerator system can achieve higher pellet speeds, has precise speed control, and is more than ten times as energy efficient. Furthermore, the use of frozen CO{sub 2} pellets instead of conventional metal, plastic, sand, or other abrasive materials that remain solid at room temperature, minimizes the waste stream. This apparatus has been used to demonstrate cleaning of various surfaces, including removal of paint, oxide coatings, metal coatings, organic coatings, and oil and grease coatings from a variety of surfaces. The design and operation of the apparatus is discussed.

  2. Role of shielding in modelling cryogenic deuterium pellet ablation

    For the better characterization of pellet ablation, the numerical LLP code has been enhanced by combining two relevant shielding mechanisms: that of the spherically expanding neutral cloud surrounding the pellet and that of the field elongated ionized material forming a channel flow. In contrast to our expectation the presence of the channel flow can increase the ablation rate although it reduces the heat flux travelling through it. The contribution of the different shielding effect in the ablation process is analysed for several pellet and plasma parameters and an ablation rate scaling is presented based on simple regression in the ASDEX Upgrade pellet and plasma parameter range. Finally the simulated results are compared with experimental data from typical ASDEX Upgrade discharges

  3. Improved model of two fuel pellets with closed canning

    In our recent model (see 23rd ETAN Conf.) of thermal and deformation state of fuel elements, only one reactor fuel pellet with its canning tube ring has been considered. in this way obtained stress results are valid for fuel pellet, while in the canning material deviation occur due to the problem of boundary conditions at the cut of the canning tube from the whole stack. To avoid this trouble, a new finite element model has been built, consisting of two fuel pellets and its interacting tube with end steal. this yields valid stress results in the lower pellet (away from the end) and its part of the canning, while the remaining results could be used in case if the analysis takes into account axially dependent power generation and associated phenomena of conduction, convection and radiative heat transfer at discontinuities of fuel rods. (author)

  4. Experimental modelling of a pilot lignocellulosic pellets stove plant

    Small-scale stoves, producing heat and hot water, are suited for domestic purposes. In order to optimise their efficiency when using lignocellulosic pellets, an important task is to do research on their real performance. The general behaviour depends on many operational factors (air flow and humidity, pressure, etc), dimension and pellet characteristics (moisture, size, raw material, density, friability, etc). In this paper, the first results and general performance of a 24 kW pellet fixed bed stove pilot plant are presented. The plant has been designed to study pellet combustion in the laboratory. The main targets are to reduce emissions of pollutants and to improve energy efficiency. Different situations can be simulated and tested due to its flexible design. Temperatures, pressures, flows and emissions are measured and analysed. An extensive study of different load conditions is presented through the application of both an experiment design technique and the later statistical analysis of the results. Fuel characterisation is also presented. (Author)

  5. Feed Pellet and Corn Durability and Breakage 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...

  6. Formulation and characterization of self emulsifing pellets of carvedilol

    Vikas Bhandari; Amelia Avachat

    2015-01-01

    The purpose of present study was aimed at developing self emulsifying drug delivery system in liquid and then in pellet form that would result in improved solubility, dissolution and permeability of the poorly water soluble drug carvedilol. Pellets were prepared using extrusion-spheronization technique incorporating liquid SEDDS (carvedilol, capmul MCM EP, cremophore EL, tween 20, propylene glycol), adsorbents ( and crospovidone), microcrystalline cellulose and binder (povidone K-30). Ternary...

  7. Radiation analysis of the ITER pellet injection system

    The results of neutronics calculations for the pellet injection system of the International Thermonuclear Experimental Reactor (ITER) are described. Hands-on maintenance of components in the pellet injection room results in a considerable simplification of maintenance support equipment and in greater system availability. The basic configuration of the pellet injection system includes small-diameter guide tubes with which the pellet may have several small-angle collisions before reaching the plasma. The pellet injector port through which the guide tubes pass will be shared with ITER plasma diagnostics, so the calculation takes into account penetrations to accommodate numerous channels for a neutron spectrometer and neutron and gamma-ray cameras. The conservative assumption of steady-state operation of ITER for 1000 days was taken as the baseline for calculating the activation of components in the pellet injection room. The plasma configuration is based on the current ITER guidelines, the first wall configuration is based on the most recently updated configuration, and the blanket configuration is based on the US proposal for the blanket. The plasma, coils, and blanket regions were analyzed with the Monte Carlo code MCNP. The transport of neutrons through the penetrations was also performed with MCNP. The pellet injection room was modeled with the two-dimensional discrete ordinates code DORT, which was also used for the transport of neutrons during operation and of gamma rays caused by activation. The activation calculations were carried out with the REBATE code. Results from this study indicate that restricted personnel access to the pellet injection room is possible, so limited hands-on maintenance can be performed on the majority of the components in the room

  8. Pelletering och brikettering av jordbruksråvaror

    Nilsson, Daniel; Bernesson, Sven

    2008-01-01

    Use of processed biofuels (pellets, briquettes) has greatly increased in Sweden in recent decades, mainly to replace fossil fuels in large boilers, e.g. in coal powder boilers. More recently, the demand from private households and residential heating systems has also increased, mainly due to conversion from fossil heating oil. This increased interest in pellets and briquettes for heating is beginning to cause a shortage of the traditional raw materials, sawdust and wood shavings, and therefor...

  9. Digestibility of pelleted rations containing diverse potato flour and urea

    Isabel Martinele

    2015-11-01

    Full Text Available The aim of this study was to evaluate ruminal in situ degradability and in vitro digestibility of dry matter (DM in concentrate supplements containing diverse potato flour pelletized with urea (0%, 4%, 8%, and 12% DM. Samples of feeds were incubated for 0, 2, 4, 8, 12, 24, 36, and 48h in the rumen of four fistulated sheep. Level of urea added had no significant effect (P>;0.05 on the soluble fraction (a or potentially degradable fraction (b of the pellets and ranged from 2.1% to 12.2% and 72.9% to 87.5%, respectively. Quadratic effects (P=0.03 of the rate of degradation of fraction "b" ranged from 4.75% h-1to 7.39% h-1; the estimated maximum value at 7.4% h-1was obtained when 5.9% urea was added to the pellet. Quadratic effects (P≤0.02 of the level of urea added to the pellets on the effective degradability (ED of DM were evaluated after considering rumen passage rates of 2.5% h-1and 8% h-1; the maximum values of ED calculated under these rumen passage rates were estimated at 6.3% to 7.3% urea in the pellets. The in vitro digestibility of DM of the pellets showed a quadratic effect (P=0.02 at different levels of urea, with a maximum value of 96.9% achieved when 7.9% urea was added to the pellets. Our results suggest that the addition of 6-8% urea to pelleted feed promotes an increase in the in vitro digestibility and ED of DM.

  10. Research Progress and Development Trend of Mycelial Pellets

    Lixin Li; Fang Ma; Zhiwei Song; Ting Li; Erkui Tang

    2015-01-01

    Mycelial pellets are generated by the fermentation of microorganisms as a particle, it has good biological activity, rapid subsidence performance and simple solid-liquid separation technology, so that it can better be used in fermentation production, wastewater treatment and as biological carrier. The researches of using mycelial pellets to ferment production, treat some kinds of wastewater as biological adsorbent and enhance efficiency of treatment wastewater as bio-carrier, were discussed i...

  11. Interstellar propulsion using a pellet stream for momentum transfer

    A pellet-stream concept for interstellar propulsion is described. Small pellets are accelerated in the solar system and accurately guided to an interstellar probe where they are intercepted and transfer momentum. This propulsion system appears to offer orders-of-magnitude improvements in terms of engineering simplicity and power requirements over any other known feasible system for transport over interstellar distance in a time comparable to a human lifespan

  12. Key Formulation Variables in Tableting of Coated Pellets

    Murthy Dwibhashyam V.S.N; Ratna J

    2008-01-01

    Multiple unit controlled release dosage forms offer various advantages over their single unit counterparts. Most of these advantages are associated with the uniform distribution of multiparticulates throughout the gastrointestinal tract. Though coated pellets can be filled into hard gelatin capsules, tablet formulation is the preferred one because of various advantages associated with it. However, compression of coated pellets is a challenging task necessitating the optimization of various fo...

  13. Are owl pellets good estimators of prey abundance?

    Analia Andrade

    2016-07-01

    Full Text Available Some ecologists have been skeptics about the use of owl pellets to estimate small mammal’s fauna. This is due to the assumptions required by this method: (a that owls hunt at random, and (b that pellets represent a random sample from the environment. We performed statistical analysis to test these assumptions and to assess the effectiveness of Barn owl pellets as a useful estimator of field abundances of its preys. We used samples collected in the arid Extra-Andean Patagonia along an altitudinal environmental gradient from lower Monte ecoregion to upper Patagonian steppe ecoregion, with a mid-elevation ecotone. To test if owls hunt at random, we estimated expected pellet frequency by creating a distribution of random pellets, which we compared with data using a simulated chi-square. To test if pellets represent a random sample from the environment, differences between ecoregions were evaluated by PERMANOVAs with Bray–Curtis dissimilarities. We did not find evidence that owls foraged non-randomly. Therefore, we can assume that the proportions of the small mammal’s species in the diet are representative of the proportions of the species in their communities. Only Monte is different from other ecoregions. The ecotone samples are grouped with those of Patagonian steppes. There are no real differences between localities in the small mammal’s abundances in each of these ecoregions and/or Barn owl pellets cannot detect patterns at a smaller spatial scale. Therefore, we have no evidence to invalidate the use of owl pellets at an ecoregional scale.

  14. Remote fabrication of pellet fuels for United States breeder reactors

    Goal of the program is to demonstrate the feasibility of fabricating breeder fuel in a remotely operated and maintained mode by 1985. Development for pellet fuel fabrication is in the engineering stage with much of the equipment for ceramic unit operations in final design or currently under testing. Results to date confirm that remote fabrication of pellet fuels is feasible. Several of the processes and equipment items are described in this report

  15. Pellet-clad interaction in water reactor fuels

    NONE

    2004-07-01

    The aim of this seminar is was to draw up a comprehensive picture of the pellet clad interaction and its impact on the fuel rod. This document is a detailed abstract of the papers presented during the following five sessions: industrial goals, fuel material behaviour in PCI situation, cladding behaviour relevant to PCI, in pile rod behaviour and modelling of the mechanical interaction between pellet and cladding. (A.L.B.)

  16. Pellet-clad interaction in water reactor fuels

    The aim of this seminar is was to draw up a comprehensive picture of the pellet clad interaction and its impact on the fuel rod. This document is a detailed abstract of the papers presented during the following five sessions: industrial goals, fuel material behaviour in PCI situation, cladding behaviour relevant to PCI, in pile rod behaviour and modelling of the mechanical interaction between pellet and cladding. (A.L.B.)

  17. Determination of organochlorine pesticides adsorbed on plastic pellets

    2016-01-01

    In the past years, several studies have revealed the presence of organic contaminants at concentrations from sub ng g–1 to mg g–1 on/in plastic pellets found in coastal environment worldwide [1,2,3]. Plastic pellets are actually industrial raw material, typically in the shape of small granules with a diameter of a few mm. They are categorized as microplastics (< 5 mm). They can be unintentionally lost in the environment during manufacturing and transport. They can subsequently ...

  18. Nuclear fuel pellet quality control using artificial intelligence techniques

    Song, Xiaolong

    Inspection of nuclear fuel pellets is a complex and time-consuming process. At present, quality control in the fuel fabrication field mainly relies on human manual inspection, which is essentially a judgement call. Considering the high quality requirement of fuel pellets in the nuclear industry, pellet inspection systems must have a high accuracy rate in addition to a high inspection speed. Furthermore, any inspection process should have a low rejection rate of good pellets from the manufacturer point of view. It is very difficult to use traditional techniques, such as simple image comparison, to adequately perform the inspection process of the nuclear fuel pellet. Knowledge-based inspection and a defect-recognition algorithm, which maps the human inspection knowledge, is more robust and effective. A novel method is introduced here for pellet image processing. Three artificial intelligence techniques are studied and applied for fuel pellet inspection in this research. They are an artificial neural network, fuzzy logic, and the decision tree method. A dynamic reference model is located on each input fuel pellet image. Then, those pixels that belong to the abnormal defect are enhanced with high speed and high accuracy. Next, the content-based features for the defect are extracted from those abno1mal pixels and used in the inspection algorithm. Finally, an automated inspection prototype system---Visual Inspection Studio---which combines machine vision and these three AI techniques, is developed and tested. The experimental results indicate a very successful system with a high potential for on-line automatic inspection process.

  19. Assessment of erbium as candidate burnable absorber for future PWR operaning cycles: A neutronic and fabrication study

    Erbium begins to play a role in the control of PWR core reactivity. Generally speaking, burnable absorbers were only used to establish fresh core equilibrium. In France, since the possibility of extending irradiation cycles by 12 to 18 months, then up to 24 and 30 months, has been envisaged, there is renewed interest in burnable absorbers. The fabrication of PWR pellets has been investigated, providing high density and a good erbium homogeneity. The pellets characteristics were consistent with the specifications of PWR fuel. However, with the present process, the grain size remains small. Studies in progress now shows that erbium is not only a valuable alternative to gadolinium, for long fuel cycles (≥18 months) but also a new fuel concept. (orig.)

  20. Levels of Polychlorinated Bihpenyls (PCBs) in plastic resin pellets collected from selected beaches in Accra and Tema

    This research seeks to investigate marine pollution along selected beaches in Accra and Tema in Ghana by measuring the levels of PCBs in plastic resin pellets. The PCB congeners identified included PCB numbers; 28, 52, 101, 105, 153, 156, 138 and 180. PCB numbers was deducted in all sample locations. The mean concentrations values were in the range of 0.4-3.23 μg/kg, 3.43-5.67 μg/kg, 0.33-2.73 μg/kg, 0.13-0.93 μg/kg and 0.13-0.2 μg/kg for PCB-28, 52, 101, 153, 180 respectively. The highest concentration of PCBs recorded in the study was that of PCB numbers 52 (5.67μg/kg), from the independence square beach. Generally, it was observed that the white pellets from most of the beaches absorbed higher levels of PCBs followed by the coloured and fouled pellets (white > coloured > discoloured). However, the coloured pellets from Tema Sakumono Beach retained higher levels of PCBs (10.3μg/kg) than the white pellets. The average concentration of PCB congeners detected ranges between 0.02 μg/kg and 2.25 μg/kg. The percentage distribution of the individual congeners are in the decreasing order of PCB 28 (43%) > PCB 52 (28%) > PCB 101 (11%), > PCB 156 (10%) > PCB 153 (5%), > PCB 180 (2%) > PCB 138 (1%) > PCB 105 (0%). The results also show that the sum total concentration of PCSs from the various sample locations ranged from 6.8 μg/kg to 47 μg/kg, with the highest concentration occurring at the Accra Independence Square Beach and the least concentration at Korle Gonno Beach. The pollution level is in the order of AISB> TSB> TMB> AACB> LB> KGB> (Accra Independence Square Beach > Tema Sakumono Beach > Tema Mighty Beach > Accra Art Center Beach Labadi Beach > Korle Gonno Beach). Results from the INAA for chlorine analysis revealed that coloured pellets had more extracted organochlorine than the fouled and the white pellets (Coloured> Fouled> White). The range of EOCI mean concentration in all samples ranged from 2.24mg/kg to 30.90 mg/kg. The range of EOCI mean

  1. Heat losses and thermal performance of commercial combined solar and pellet heating systems

    Fiedler, Frank; Persson, Tomas; Bales, Chris; Nordlander, Svante

    2004-01-01

    Various pellet heating systems are marketed in Sweden, some of them in combination with a solar heating system. Several types of pellet heating units are available and can be used for a combined system. This article compares four typical combined solar and pellet heating systems: System 1 and 2 two with a pellet stove, system 3 with a store integrated pellet burner and system 4 with a pellet boiler. The lower efficiency of pellet heaters compared to oil or gas heaters increases the primary en...

  2. Roll pelleting. Evaluation of a new technique for producing pellets from bioash suitable for forest nutrient; Valspelletering. Utvaerdering och uppfoeljning av pilotprojekt omfattande ny teknik foer framstaellning av pellets foer aaterfoering av bioaska till skogsmark

    Windelhed, Kjell [Sycon Teknikkonsult AB, Stockholm (Sweden)

    2000-05-01

    Roll pelleting has earlier been tested in laboratory scale as a technique for processing wood ash to a product suitable to be spread into forest and thereby returning mineral nutrients to forest soils. The roll pelleting technique for producing pellets has, in this project, been evaluated in full scale. A container-based pelleting machine has been tested during nine months in AssiDomaen Froevi and Stora Enso Fors. Totally about 1500 tons of pellets were produced. The project started with a laboratory leach study. This study showed that pellets produced in a laboratory pelleting machine has a very low leach rate, in fact so low that the pellets seems possible to be spread on clearcuts. The pelleting machine was designed for a capacity of 5 tons per hour but the test indicated that production of 10 tons per hour was possible. The evaluation showed that this technique is suitable for producing pellets intended for returning nutrients to forest soils. However, it is important to start with a well humidified wood ash and to connect the control system for the humidification mixer with the pelleting machine to get an automatic system. Further, spreading of the pellets with a common disc spreader has been tested. The test turned out successful.

  3. Formulation and characterization of self emulsifing pellets of carvedilol

    Vikas Bhandari

    2015-09-01

    Full Text Available The purpose of present study was aimed at developing self emulsifying drug delivery system in liquid and then in pellet form that would result in improved solubility, dissolution and permeability of the poorly water soluble drug carvedilol. Pellets were prepared using extrusion-spheronization technique incorporating liquid SEDDS (carvedilol, capmul MCM EP, cremophore EL, tween 20, propylene glycol, adsorbents ( and crospovidone, microcrystalline cellulose and binder (povidone K-30. Ternary phase diagram was constructed to identify different oil-surfactant-cosurfactant mixtures according to the proportion of each point in it. The optimal CAR-SEDDS pellets showed a quicker redispersion with a droplet size of the reconstituted microemulsion being 160.47 nm, which was almost unchanged after solidification. SEM analysis confirmed good spherical appearance of solid pellets; DSC and XRD analysis confirmed that there was no crystalline carvedilol in the pellets. Pellets were then capable of transferring lipophilic compounds into the aqueous phase and significantly enhancing its release with respect to pure drug.

  4. Effect of aluminum oxide on the compressive strength of pellets

    Jian-liang Zhang; Zhen-yang Wang; Xiang-dong Xing; Zheng-jian Liu

    2014-01-01

    Analytical-reagent-grade Al2O3 was added to magnetite ore during the process of pelletizing, and the methods of mercury intru-sion, scanning electron microscopy, and image processing were used to investigate the effect of Al2O3 on the compressive strength of the pellets. The results showed that, as the Al2O3 content increased, the compressive strength of the pellets increased slightly and then decreased gradually. When a small amount of Al2O3 was added to the pellets, the Al2O3 combined with fayalite (2FeO·SiO2) and the aluminosilicate (2FeO·2Al2O3·5SiO2) was generated, which releases some iron oxide and reduces the inhibition of fayalite to the solid phase of consolidation. When Al2O3 increased sequentially, high melting point of Al2O3 particles hinder the oxidation of Fe3O4 and the recrystallization of Fe2O3, making the internal porosity of the pellets increase, which leads to the decrease in compressive strength of the pellets.

  5. Angular response of alanine samples: From powder to pellet

    Alanine radicals produced by irradiation can be observed through the ESR measurement of powder or in a pellet with an angular response. There are five main peaks in the ESR alanine spectrum. Usually, the central peak amplitude (A1) is chosen to perform dose measurements because it is the largest. Looking at the angular response it seems that the peak amplitude (A2) shows lower maximal deviation and standard deviations. The angular response exists from the first step of the process as powder through the granular form until the final compact pellet form. Results about the angular response on pure alanine powders and its evolution during the manufacturing process of homemade pellets, as well as commercial pellets from different suppliers are presented. The evolution of the angular response with time gives information about the stability of radicals. The manufacturing process of pellet also influences the stabilization of the radicals produced by irradiation; therefore pellet reproducibility. This study raises questions and makes proposals for a better approach to reduce measurement uncertainties for high and low doses measurements

  6. Design of a tritium pellet injector for TFTR

    The TFTR tritium pellet injector (TPI) is designed to provide a tritium pellet fueling capability with pellet speeds in the 1- to 3 km/s-range for the TFTR D-T phase. The existing TFTR deuterium pellet injector is being modified at Oak Ridge National Laboratory to provide a fourshot, tritium-compatible, pipe-gun configuration with three upgraded single-stage pneumatic guns a two -stage light gas gun driver. The pipe gun concept has been qualified for tritium operation by the tritium proof-of-principle injector experiments conducted on the Tritium Systems Test Assembly at Los Alamos National Laboratory. In these experiments, tritium and D-T pellets were accelerated to speeds near 1.5 km/s. The TPI is being designed for pellet sizes in the range from 3.43 to 4.0 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 will be controlled by a programmable logic controller. 7 refs., 4 figs

  7. Design of a tritium pellet injector for TFTR

    This paper reports on the TFTR tritium pellet injector (TPI) designed to provide a tritium pellet fueling capability with pellet speeds in the 1-to 3 km/s-range for the TFTR D-T phase. The existing TFTR deuterium pellet injector (DPI) is being 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 pipe gun concept has been qualified for tritium operation by the tritium proof-of-principle (TPOP) injector experiments conducted on the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory. In these experiments, tritium and D-T pellets were accelerated to speeds near 1.5 km/s. The TPI is being designed for pellet sizes in the range from 3.43 to 4.0 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 will be controlled by a programmable logic controller (PLC)

  8. Determination of gas residues in uranium dioxide pellets

    The measurement of low amounts of residual gases, excluding water, in ceramic grade uranium dioxide pellets, using high temperature vacuum extraction technique, is dealt with. The high temperature extraction gas analysis apparatus was designed and assembled for sequential analysis of up to eight uranium dioxide pellets by run. The system consists of three major units, namely outgassing unit, transfer unit and analytical unit. The whole system is evacuated to a final pressure of less then 10-5 torr. A weighed pellet is transfered into the outgassing unit for subsequent dropping into a Platinum-Rhodium crucible which is heated inductively up to 16000C during 30 minutes. The released gases are imediately transfered from the outgassing to analytical unit passing through a cold trap at -950C to remove water vapor. The gases are transfered to previously calibrated volumetric bulb where the total pressure and temperature are determined. An estimate of the gas content in the pellets at STP condition is obtained from the measured volume, pressure and temperature of the gas mixture by applying ideal gases equation. Analysis to two lots (fourteen samples) of uranium dioxide pellets by the method described here indicated a mean gas content of 0,060cm3/g UO2. The lower limit of this technique is 0,03cm3/g UO2 (STP). The time required for the analysis of eight pellets is about 9 hours

  9. Properties of tritium inferred from pellet injector experiments

    This paper discusses the tritium proof-of-principle (TPOP) experiment, designed and built by Oak Ridge National Laboratory (ORNL) to demonstrate the formation and acceleration of the worlds first tritium pellets for fueling of future fusion reactors. Many parameters measured during the course of the experiment have been used to evaluate the physical properties of solid tritium. Pellet size was measured as a function of equilibrium fill pressure. a model was developed to predict this information form values of thermal conductivity, vapor pressure, and density reported in the literature. Good agreement between theory and experiment was found for both deuterium and tritium pellets. Evaluation of breakaway pressure data for deuterium pellets indicates that the shear strength of deuterium is about equal to its ultimate tensile strength. Tritium shear strength appears to be about twice that of deuterium at temperatures around 8K. The reduction in pellet diameter due to barrel erosion for deuterium was about twice that for tritium pellets at a given velocity. This about also indicative of the greater strength of tritium relative to deuterium

  10. Radiation-induced grafting of styrene on polypropylene pellets

    The changes of radiation-induced in polypropylene (PP) pellets exposed to gamma irradiation in inert atmosphere were investigated in correlation with the applied doses (10 and 50 kGy). Also, results from the grafting of styrene onto PP pellets using simultaneous irradiation at the same doses are presented. The grafting reaction was carried out using toluene as solvent, under nitrogen atmosphere and at room temperature. The properties of the irradiated and grafted PP pellets were studied using Melt Flow Index, thermal analysis (TG and DSC), and ATR-IR. The degree of grafting (DOG) for the grafted pellets was gravimetrically determined. The results showed that radiation-induced graft polymerization on pellets were successfully obtained and the influence of dose irradiated did not change the thermal properties in spite of the increase in the MFI and consequently this increase in the viscosity results an decrease the molecular mass. The MFI for grafted pellets was not achievable because the high degree of viscosity of polymer, even arising the test temperature, the polymer was not flow enough. (author)

  11. New fabrication process of large grain pellet for LWR

    'Oxidation-sintering pellets' and 'Al2O3/SiO2 additive pellets' were developed. Both pellets will be used for high burnup due to their good FGR and PCI properties. In the 'oxidation-reduction sintering process', U3O8 powder is added to UO2 powder as a source of oxygen to produce U4O9 and to get large grain pellets. Atmosphere of the oxidation sintering process is O2+N2 and the sintering temperatures for both the oxidation and the reduction processes are relatively low compared with that for the standard sintering process. In Al2O3/SiO2 addition, Al2O3/SiO2 covers UO2 grain and enhances its grain growth. Contents of Al2O3 and SiO2 are very low (∼50,50 PPM), therefore there is little impact on a reprocessing process. Both type of pellets are under irradiation in test reactors and a commercial reactor as demonstration fuels. We will choose one type of pellet after PIE, and will use it for high burnup (55 GWd/t) as commercial fuels. (author)

  12. Key formulation variables in tableting of coated pellets

    Murthy Dwibhashyam V.S.N

    2008-01-01

    Full Text Available Multiple unit controlled release dosage forms offer various advantages over their single unit counterparts. Most of these advantages are associated with the uniform distribution of multiparticulates throughout the gastrointestinal tract. Though coated pellets can be filled into hard gelatin capsules, tablet formulation is the preferred one because of various advantages associated with it. However, compression of coated pellets is a challenging task necessitating the optimization of various formulation and process variables. The key formulation variables include composition, porosity, size, shape and density of the pellets; type and amount of polymer coating; nature, size and amount of tableting excipients. The pellet core should be strong with some degree of plasticity. It should be highly porous, small, with an irregular shape. The critical density to achieve prolonged release was reported to lie between 2.4 and 2.8 g/cm 3 . Acrylic polymer films are more flexible and more suitable for the coating of pellets to be compressed into tablets. Thicker coatings offer better resistance to frictional forces. Solvent based coatings are more flexible and have a higher degree of mechanical stability than the aqueous based ones. The tableting excipients should have cushioning property. They should not be significantly different in size and density from those of the pellet cores in order to avoid segregation. Addition of 30%-60% of tableting excipients is necessary to avoid any damage to the polymer coat and to retain its functional property.

  13. FORMULATION AND EVALUATION OF METAPROLOL SUCCINATE EXTENDED RELEASE PELLETS

    Ahishek Perumalla

    2012-11-01

    Full Text Available The aim and of the present study is to develop a pharmaceutically stable and quality improved formulation of Metoprolol succinate extended release pellets. To achieve this goal various prototype formulation trials were formulated and the evaluated with respect to the various quality controls such as dissolution, assay and stability studies will be under taken. Metoprolol succinate is used in the treatment of hyper tension, angina pectoris (chest pain and myocardial infarction. The study was undertaken with an aim to formulate Metoprolol succinate extended release pellets. The optimized batch MSER CF7 is made up of 7% wetting agent and 4.5% binder. The evaluation tests that were conducted for the pellets also showed satisfactory results.The best trial was optimized by comparing the drug release profile with the innovator and the MSER F7 showed better results compared to the other formulations and the evaluation studies were conducted for the MSER F7. It showed good results in formulation of stable dose.The pellets were evaluated for the flow properties, sieve analysis and accelerated stability studies for 3months. The pellets showed good flow properties and also showed uniform size which indicates uniform coating.Finally we concluded that the Metoprolol succinate pellets MSER F7 are prepared and these showed good physico-chemical properties and the dissolution results showed satisfactory results when compared with the innovator drug.

  14. Modeling operation mode of pellet boilers for residential heating

    In recent years the consumption of wood pellets as energy source for residential heating lias increased, not only as fuel for stoves, but also for small-scale residential boilers that, produce hot water used for both space heating and domestic hot water. Reduction of fuel consumption and pollutant emissions (CO, dust., HC) is an obvious target of wood pellet boiler manufacturers, however they are also quite interested in producing low- maintenance appliances. The need of frequent maintenance turns in higher operating costs and inconvenience for the user, and in lower boiler efficiency and higher emissions also. The aim of this paper is to present a theoretical model able to simulate the dynamic behavior of a pellet boiler. The model takes into account many features of real pellet boilers. Furthermore, with this model, it is possible to pay more attention to the influence of the boiler control strategy. Control strategy evaluation is based not only on pellet consumption and on total emissions, but also on critical operating conditions such as start-up and stop or prolonged operation at substantially reduced power level. Results are obtained for a residential heating system based on a wood pellet boiler coupled with a thermal energy storage. Results obtained so far show a weak dependence of performance in terms of fuel consumption and total emissions on control strategy, however some control strategies present some critical issues regarding maintenance frequency

  15. Fabrication and Resintering of Annular UO2 Pellet

    Nuclear fuel is one of the most important components in a PWR affecting its safety and economy. The traditional PWR fuel pellet has a shape of cylindrical tablets of about 800 μm in diameter with a chamfer and dishes. A significant reduction in its failure rate has resulted from the improvements in fuel and cladding quality. Enhanced fuel assembly design allowed appreciable power density increases. However, it is difficult to achieve a significant increase of a power density under the current fuel pin design. Recently, Massachusetts Institute of Technology (MIT) has proposed an annular UO2 fuel with an internal cooling of each fuel rod. Annular fuel pellets with a voided central region have been used in VVER reactors without an internal cooling. Annular fuels with both internal and external cooling have been proposed for high temperature gas cooled reactors. However, commercial PWR reactors have not used such annular internally and externally cooled fuel rods, yet. There must be a lot of considerations in the various fields to introduce an annular internally and externally cooled fuel to commercial PWR reactors. The dimension tolerance and the thermal stability of a pellet are very important from the viewpoint of fabrication technology, because they have an influence on the size of the gap between the pellet and the inner/outer claddings. In this study, annular UO2 pellets with various densities were fabricated and then a resintering test was conducted. The changes of dimension and density of the sintered pellets were characterized

  16. Potential greenhouse gas benefits of transatlantic wood pellet trade

    Power utility companies in the United Kingdom are using imported wood pellets from the southern region of the United States for electricity generation to meet the legally binding mandate of sourcing 15% of the nation’s total energy consumption from renewable sources by 2020. This study ascertains relative savings in greenhouse gas (GHG) emissions for a unit of electricity generated using imported wood pellet in the United Kingdom under 930 different scenarios: three woody feedstocks (logging residues, pulpwood, and logging residues and pulpwood combined), two forest management choices (intensive and non-intensive), 31 plantation rotation ages (year 10 to year 40 in steps of 1 year), and five power plant capacities (20–100 MW in steps of 20 MW). Relative savings in GHG emissions with respect to a unit of electricity derived from fossil fuels in the United Kingdom range between 50% and 68% depending upon the capacity of power plant and rotation age. Relative savings in GHG emissions increase with higher power plant capacity. GHG emissions related to wood pellet production and transatlantic shipment of wood pellets typically contribute about 48% and 31% of total GHG emissions, respectively. Overall, use of imported wood pellets for electricity generation could help in reducing the United Kingdom’s GHG emissions. We suggest that future research be directed to evaluation of the impacts of additional forest management practices, changing climate, and soil carbon on the overall savings in GHG emissions related to transatlantic wood pellet trade. (paper)

  17. Absorber materials in CANDU PHWRs

    In a CANDU reactor the fuel channels are arranged on a square lattice in a calandria filled with heavy water moderator. This arrangement allows five types of tubular neutron absorber devices to be located in the relatively benign environment of low pressure, low temperature heavy water between neighbouring rows or columns of fuel channels. This paper will describe the roles of the devices and outline the design requirements of the absorber component from a reactor physics viewpoint. Nuclear heating and activation problems associated with the different absorbers will be briefly discussed. The design and manufacture of the devices will be also discussed. The control rod absorbers and shut off materials are cadmium and stainless steel. In the tubular arrangement, the cadmium is sandwiched between stainless steel tubes. This type of device has functioned well, but there is now concern over the availability and expense of cadmium which is used in two types of CANDU control devices. There are also concerns about the toxicity of cadmium during the fabrication of the absorbers. These concerns are prompting AECL to study alternatives. To minimize design changes, pure boron-10 alloyed in stainless steel is a favoured option. Work is underway to confirm the suitability of the boron-loaded steel and identify other encapsulated absorber materials for practical application. Because the reactivity devices or their guide tubes span the calandria vessel, the long slender components must be sufficiently rigid to resist operational vibration and also be seismically stable. Some of these components are made of Zircaloy to minimize neutron absorption. Slow irradiation growth and creep can reduce the spring tension, and periodic adjustments to the springs are required. Experience with the control absorber devices has generally been good. In one instance liquid zone controllers had a problem of vibration induced fretting but a redesigned back-fit resolved the problem. (author). 3 refs, 8

  18. Arresting and supplying apparatus for increasing pellet impact drilling speed per run

    Kovalyov, A. V.; Isaev, Ye D.; Veryevkin, A. V.; Gorbenko, V. M.; Ulyanova, O. S.

    2015-11-01

    The paper describes pellet impact drilling which might be used to increase the drilling rate and the penetration rate of hard and tough rock drilling. Pellet impact drilling implies rock destruction by metal pellets having high kinetic energy in the immediate vicinity of the earth formation encountered. The pellets are recirculated in the bottom of the bore hole by a high velocity fluid jet, which is the principle component of the ejector pellet impact drill bit. The arresting and supplying apparatus is supposed to increase speed per run in pellet impact drilling, as it not only replenishes the pellets but also supplies and then picks up the pellets from the bottom hole. The paper presents the design of the pellet-supplying component which ensures a portion of pellets supply to the bottom hole.

  19. Self-Navigation of Laser Drivers on Injected IFE Direct Drive Pellets

    Full text: There are many serious obstacles complicating the classical direct drive IFE scheme -even putting in doubts its practical feasibility. Among the most serious ones is the insufficient predictability of the injected pellets' trajectories resulting from their expected interactions with remnants of previous fusion explosions due to the considered 5-10 Hz repetition rate. This is one of the reasons why the indirect drive scheme -despite its higher demand on laser energy -seems to be currently considered a more serious IFE candidate. The corresponding hohlraum targets are by three orders of magnitude heavier compared to their direct drive counterparts thus allowing for more reliable prediction of their trajectories. In this contribution a recent progress achieved in the stimulated Brillouin scattering (SBS) phase conjugating mirror (PCM) based inertial fusion energy (IFE) approach proposed recently as an alternative to the IFE classical approach mentioned above will be presented. By taking care of automatic self-navigation of every individual laser beam on injected pellets with no need for any final optics adjustment this technology is of particular importance to the direct drive scheme. Conceptual design of one typical laser driver will be shown and its features discussed. This approach would allow for higher number of laser drivers to be employed. Operating with lower energies (∼ 1 kJ - thus avoiding the optics damage caused by perpendicular SBS) such laser drivers would be easier to design for the required repetition rate. 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 upper limits on the energies absorbed after their

  20. Direct dissolution and supercritical fluid extraction of uranium from UO2 powder, granule, green pellet and sintered pellet

    In the present work, direct dissolution and extraction of UO2 from the solid rejects various stages of fuel fabrication viz. powder granules green pellet and, sintered pellet has been studied. Powder and granules could be easily dissolved in TBP-HNO3 complex at 50 deg C., whereas in case of green and sintered pellets at elevated temperature at raised to 80 deg C in TBP-HNO3 complex. With supercritical (SC) CO2 alone the efficiency was ∼70%. But with SC CO2 +2.5% TBP, the efficiency was ∼95% for powder and granules, and ∼60% for green and sintered pellets. Nearly complete extraction (∼99%) was achievable for SC CO2+ 2.5 % TTA in all cases. The method has distinct advantage of elimination of acid usage and minimization of liquid waste generation. (author)

  1. Development of a Tritium Extruder for ITER Pellet Injection

    M.J. Gouge; P.W. Fisher

    1998-09-01

    As part of the International Thermonuclear Experimental Reactor (ITER) plasma fueling development program, Oak Ridge National Laboratory (ORNL) has fabricated a pellet injection system to test the mechanical and thermal properties of extruded tritium. Hydrogenic pellets will be used in ITER to sustain the fusion power in the plasma core and may be crucial in reducing first-wall tritium inventories by a process of "isotopic fueling" in which tritium-rich pellets fuel the burning plasma core and deuterium gas fuels the edge. This repeating single-stage pneumatic pellet injector, called the Tritium-Proof-of-Principle Phase II (TPOP-II) Pellet Injector, has a piston-driven mechanical extruder and is designed to extrude and accelerate hydrogenic pellets sized for the ITER device. The TPOP-II program has the following development goals: evaluate the feasibility of extruding tritium and deuterium-tritium (D-T) mixtures for use in future pellet injection systems; determine the mechanical and thermal properties of tritium and D-T extrusions; integrate, test, and evaluate the extruder in a repeating, single-stage light gas gun that is sized for the ITER application (pellet diameter -7 to 8 mm); evaluate options for recycling propellant and extruder exhaust gas; and evaluate operability and reliability of ITER prototypical fueling systems in an environment of significant tritium inventory that requires secondary and room containment systems. In tests with deuterium feed at ORNL, up to 13 pellets per extrusion have been extruded at rates up to 1 Hz and accelerated to speeds of 1.0 to 1.1 km/s, using hydrogen propellant gas at a supply pressure of 65 bar. Initially, deuterium pellets 7.5 mm in diameter and 11 mm in length were produced-the largest cryogenic pellets produced by the fusion program to date. These pellets represent about a 10% density perturbation to ITER. Subsequently, the extruder nozzle was modified to produce pellets that are almost 7.5-mm right circular

  2. Communal pellet deposition sites of himalayan musk deer (Moschus chrysogaster) and associated vegetation composition

    Shrestha, Bhakta Bahadur

    2012-01-01

    The Himalayan musk deer (Moschus chrysogaster), found in the sub-alpine and alpine vegetation of the Himalayan region, is one of the endangered deer species of Nepal. This study conducted in the Langtang National Park, Nepal analyzed how the musk deer select their communal pellet deposition sites, compared vegetation at the pellet deposition sites with adjacent sites (5-10m from a pellet site) and control sites (30 m from pellet site without pellet groups) and explored the potential role o...

  3. Mushroom plasmonic metamaterial infrared absorbers

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors

  4. Carbon Absorber Retrofit Equipment (CARE)

    Klein, Eric [Neumann Systems Group, Incorporated, Colorado Springs, CO (United States)

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  5. Postirradiation examination of JOYO MK-II control rods. Irradiation performance of absorber pins

    Postirradiation examinations of JOYO MK-II control rods have been carried out since 1983, where 16 subassemblies with total 110 absorber pins of initial load to the fifth reload control rods have been subjected to a number of both non-destructive and destructive examinations. In the course of postirradiation examinations, a cracking of cladding tube was found in the total 15 absorber pins in five control assemblies. This paper indicates the results of postirradiation examinations and analysis of absorber pin performance using CORAL code to elucidate the cause of absorber pin cracking in JOYO MK-II control rods. The cause of cladding failure was attributed to the ACMI where the gap closure due to relocation of B4C pellet took place from early times of irradiation. The code analysis by CORAL indicated that the cladding strain due to ACMI was not fully absorbed by the irradiation creep and that the plastic strain became large enough to make a fracture of absorber pins with an increasing burnup. (J.P.N.)

  6. Roasting Properties of Pellets With Iron Concentrate of Complex Mineral Composition%Roasting Properties of Pellets With Iron Concentrate of Complex Mineral Composition

    FAN Jian-jun; QIU Guan-zhou; JIANG Tao; GUO Yu-feng; CAI Mei-xia

    2011-01-01

    Investigation was conducted on roasting properties of pellets with an iron concentrate of complex mineral composition. The results indicated that the pellets of complex mineral composition concentrate required higher pre- heating temperature and longer pr

  7. Developments in MOX fuel pellet fabrication technology: Indian experience

    India is interested in mixed oxide (MOX) fuel technology for better utilisation of its nuclear fuel resources. In view of this, a programme involving MOX fuel design, fabrication and irradiation in research and power reactors has been taken up. A number of experimental irradiations in research reactors have been carried out and a few MOX assemblies of ''All Pu'' type have been loaded in our commercial BWRs at Tarapur. An island type of MOX fuel design is under study for use in PHWRs which can increase the burn-up of the fuel by more than 30% compared to natural UO2 fuel. The MOX fuel pellet fabrication technology for the above purpose and R and D efforts in progress for achieving better fuel performance are described in the paper. The standard MOX fuel fabrication route involves mechanical mixing and milling of UO2 and PuO2 powders. After detailed investigations with several types of mixing and milling equipments, dry attritor milling has been found to be the most suitable for this operation. Neutron Coincident Counting (NCC) technique was found to be the most convenient and appropriate technique for quick analysis of Pu content in milled MOX powder and to know Pu mixing is homogenous or not. Both mechanical and hydraulic presses have been used for powder compaction for green pellet production although the latter has been preferred for better reproducibility. Low residue admixed lubricants have been used to facilitate easy compaction. The normal sintering temperature used in Nitrogen-Hydrogen atmosphere is between 1600 deg. C to 1700 deg. C. Low temperature sintering (LTS) using oxidative atmospheres such as carbon dioxide, Nitrogen and coarse vacuum have also been investigated on UO2 and MOX on experimental scale and irradiation behaviour of such MOX pellets is under study. Ceramic fibre lined batch furnaces have been found to be the most suitable for MOX pellet production as they offer very good flexibility in sintering cycle, and ease of maintainability under

  8. Measurements of the delivered doses from 6 MV radiotherapy generators in the hospitals of Korea by TL pellets

    Kim, J.L.; Lee, J.I.; Kim, J.S.; Chang, S.Y. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Ji, Y.H. [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Park, Y.W. [Korea Institute for Nuclear Safety, Daejeon (Korea, Republic of)

    2006-07-01

    Full text of publication follows: Radiation delivered doses from radiotherapy generators for 24 hospitals in Korea were measured for photon beam with energy of 6 MV to provide a quality audit of the delivered dose to patients by new K.L.T.-300 (LiF:Mg,Cu,Si, Korea) and G.R.-200( (LiF:Mg,Cu,P, China) thermoluminescence (T.L.) pellets as transfer dosimeter. The IAEA/Who has performed T.L.D. audits to verify calibration of the beams by T.L. powder, but T.L. pellets were used in this study because element correction factor (E.C.F.) for each T.L. pellet could be accurately derived and be handled conveniently as compared with the powder. After calibrated the radiotherapy radiation by P.T.W. 30006 ionization chamber, the T.L. pellets were irradiated in a 10 x 10 x 10 cm PMMA perspex phantom, not in a water phantom, for the convenient use and easy handling and installation in the hospital. The correction factors for PMMA to water phantom were measured in the other literature.[1] The results show that the differences in irradiation doses with measured doses by T.L. pellets are in the acceptance limits of {+-} 5 % recommended by ICRU and IAEA for all of the radiotherapy systems [2, 3], even though the hospitals which do not have radiation physicist to maintain the radiotherapy systems show a little higher discrepancy than those which have the physicist. This evaluation program of radiation dose for the systems will be extended to the all of the radiotherapy systems (56 radiotherapy hospitals in Korea) for setup the quality audit system of the radiotherapy radiation delivered the patients in Korea. References: [1]. J.L.Kim et. al., Energy Responses of LiF Series TL Pellets to High Energy Photons in the Energy Range from 1.25 to 21 MV, 14h Solid State Dosimetry Conference, Yale (2004). [2]. ICRU, Radiation Dosimetry: Electro n Beams with Energies Between 1 and 50 MeV, ICRP Rep. 35, (1984). [3]. IAEA, Absorbed Dose Determination in Phantom and Electron Beams, IAEA Tech. Rep

  9. Wood pellets and work environment; Traepiller og arbejdsmiljoe

    Skov, S.

    2012-07-01

    The project aim was to evaluate the working environment in the production, transport and use of wood pellets. Furthermore, obtained knowledge and guidelines should be disseminated to relevant audiences. The first aim was achieved by making dust measurements at various relevant locations and analyze the results. Several technical problems regarding the measurements occurred during the project. In general, the manual handling of pellets often is a short-term task, which limits the amount of dust that can be collected on the sampling filter. The solution to this problem could be the use of in situ monitoring equipment, however, this technic did not work well for wood dust. Dissemination is mainly done by publishing the findings and guidelines on the webpage www.fyrmedpiller.dk. The result shows that there are widespread dust problems associated with the use and handling of pellets. The result may have been expected in the wood pellet industry, which has been reluctant to support this project. Legislation on the working environment has set a threshold limit for the dust concentration in the air on max 1 mg of dust per cubic meters of air over a working day and in over shorter periods this limit may be doubled. These threshold values were exceeded in many cases. Brief overview: The production of pellets takes place in a very dusty working environment, but the specific pelletizing and bagging processes only produce limited amounts of dust. The dust problems are major in the large warehouses where the handling of the raw material for the pellets increases the dust concentration in the air to levels that by far exceeds the legal threshold values. The work is mainly carried out from the cabin of different machines e.g. loaders and bobcats. It turns out that the average dust concentration in these cabins with filters also exceeds the threshold values. The transports of wood pellets include loading, unloading and delivery of loose pellets, all situations that are critical

  10. Waveform-dependent absorbing metasurfaces

    Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F

    2014-01-01

    We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.

  11. Study of an electroacoustic absorber

    Rodríguez de Antonio, Javier

    2008-01-01

    El problema de la atenuación del ruido de baja frecuencia todavía persiste pese a que ha sido ampliamente estudiado. Las técnicas para absorber ruido de alta frecuencia (superior a 500 Hz), como son los materiales porosos, resonadores de Helmholtz o espumas no ofrecen resultados aceptables a bajas frecuencias. Serían necesarios volúmenes impracticables de materiales porosos para intentar absorber frecuencias menores a 500 Hz, y lo mismo ocurre con los resonadores de Helmholtz. Esta ineficacia...

  12. Perfectly Reflectionless Omnidirectional Electromagnetic Absorber

    Sainath, Kamalesh

    2014-01-01

    We demonstrate the existence of metamaterial blueprints describing, and fundamental limitations concerning, perfectly reflectionless omnidirectional electromagnetic absorbers (PR-OEMA). Previous attempts to define PR-OEMA blueprints have led to active (gain), rather than passive, media. We explain this fact and unveil new, distinct limitations of true PR-OEMA devices including the appearance of an "electromagnetic horizon" on physical solutions. As practical alternatives, we introduce two new OEMA blueprints. While these two blueprints do not correspond to reflectionless media, they are effective in absorbing incident waves in a manner robust to incident wave diversity.

  13. Diffusion coefficients for absorbing materials

    A method to improve the diffusion results for systems containing strong absorbers is described. Each absorbing material is transformed into an equivalent rectangle. Transport and diffusion calculations in slab geometry are performed for both directions of the rectangle, and group-dependent diffusion coefficients are determined by matching the outgoing currents. Test problems comprise a critical slab, a compact PWR fuel element storage pool and two BWR fuel elements with a control rod and a poison cell. The multiplication factors of these systems are calculated with an accuracy of 1 to 2%. (Auth.)

  14. Adaptive inertial shock-absorber

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  15. Anomalous Diffusion with Absorbing Boundary

    Kantor, Yacov; Kardar, Mehran

    2007-01-01

    In a very long Gaussian polymer on time scales shorter that the maximal relaxation time, the mean squared distance travelled by a tagged monomer grows as ~t^{1/2}. We analyze such sub-diffusive behavior in the presence of one or two absorbing boundaries and demonstrate the differences between this process and the sub-diffusion described by the fractional Fokker-Planck equation. In particular, we show that the mean absorption time of diffuser between two absorbing boundaries is finite. Our res...

  16. Diagnostics and camera strobe timers for hydrogen pellet injectors

    Hydrogen pellet injectors have been used to fuel fusion experimental devices for the last decade. As part of developments to improve pellet production and velocity, various diagnostic devices were implemented, ranging from witness plates to microwave mass meters to high speed photography. This paper will discuss details of the various implementations of light sources, cameras, synchronizing electronics and other diagnostic systems developed at Oak Ridge for the Tritium Proof-of-Principle (TPOP) experiment at the Los Alamos National Laboratory's Tritium System Test Assembly (TSTA), a system built for the Oak Ridge Advanced Toroidal Facility (ATF), and the Tritium Pellet Injector (TPI) built for the Princeton Tokamak Fusion Test Reactor (TFTR). Although a number of diagnostic systems were implemented on each pellet injector, the emphasis here will be on the development of a synchronization system for high-speed photography using pulsed light sources, standard video cameras, and video recorders. This system enabled near real-time visualization of the pellet shape, size and flight trajectory over a wide range of pellet speeds and at one or two positions along the flight path. Additionally, the system provides synchronization pulses to the data system for pseudo points along the flight path, such as the estimated plasma edge. This was accomplished using an electronic system that took the time measured between sets of light gates, and generated proportionally delayed triggers for light source strobes and pseudo points. Systems were built with two camera stations, one located after the end of the barrel, and a second camera located closer to the main reactor vessel wall. Two or three light gates were used to sense pellet velocity and various spacings were implemented on the three experiments. Both analog and digital schemes were examined for implementing the delay system. A digital technique was chosen

  17. Pellet-clad mechanical interactions: Pellet-clad bond failure and strain relief

    The effects of pellet-clad mechanical interaction would be expected to be particularly severe in the presence of bonding between the fuel and the cladding. However, such bonding is observed far more frequently than is corresponding cladding damage. It has recently been shown that the radial stress in the bond during power changes is very large and tensile, and thus likely to cause failure of the bond. In this paper the likely azimuthal extent of this de-bonding is considered, and the relief of hoop stress which this offers is assessed. It is shown that the magnitude of this relief is such as to provide an explanation of the low cladding failure rate observed. (orig.)

  18. Pyrolysis Model of Single Biomass Pellet in Downdraft Gasifier

    薛爱军; 潘继红; 田茂诚; 伊晓璐

    2016-01-01

    By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a one-dimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolysis zone of downdraft gasifier. The simulation results in inert atmosphere and pyrolysis zone agree well with the published experimental results. The pyrolysis of biomass pellets in pyrolysis zone is investigated, and the results show that the estimated convective heat transfer coefficient and emissivity coefficient are suitable. The mean pyro-lysis time is 15.22%, shorter than that in inert atmosphere, and the pellet pyrolysis process in pyrolysis zone belongs to fast pyrolysis. Among the pyrolysis products, tar yield is the most, gas the second, and char the least. During pyrolysis, the temperature change near the center is contrary to that near the surface. Pyrolysis gradually moves inwards layer by layer. With the increase of pyrolysis temperature and pellet diameter, the total pyrolysis time, tar yield, char yield and gas yield change in different ways. The height of pyrolysis zone is calculated to be 1.51—3.51 times of the characteristic pellet diameter.

  19. Development of automatic surface defect inspection of fuel pellets, (1)

    Automatic surface defect inspection of nuclear fuel pellets at the last stage of pellet fabrication process has been recently requested in order to reduce the radiation dose of operators. Especially, nuclear fuel such as PuO2-UO2 pellets must be set apart when they do not meet certain standards. Most of the fuel pellets are cylindrical sintered bodies with flat ends. The cracks, chips and fissures of these finished products have been inspected with eyes so far. However, such inspection is not accurate enough to find defects. Moreover, since fuel pellets are radioactive, mechanization of the inspection process is highly desirable in view of safety. At first, the inspection method with optical appliances was inadequate in the reliability and efficiency. In this paper, detection principle, inspection apparatus such as visual inspection machine, cylindrical-chip inspection unit, corner inspection device and cylindrical surface inspection device, and some experimental results, for example, correlation between defective areas and output pressure in corner inspection device, correlation between number of chips at the corner and output pressure, and correlation between output power and defective area on the pneumatic inspection method are reported. (Nakai, Y.)

  20. Chemisorption of uranium hexa-fluoride on sodium fluoride pellets

    This paper comprises kinetics of chemical reaction or rather chemisorption of uranium hexafluoride gas on sodium fluoride pellets. The chemisorption is essentially irreversible at room temperature, while the process reverses at high temperature above 280 deg C. This chemisorption process was experimentally conducted in static condition at room temperature and its kinetics was studied. In the experiments, practically pure UF6 was used and the effects of gas pressure and weight of NaF pellets, were studied. In this heterogenous reaction, in which diffusion through ash layer is followed by chemical reaction, the reaction part is instantaneous and is first order with respect to gas concentration. Since the process of chemisorption is not only pure chemical reaction but also gas diffusion through ash layer, the rate constant depreciates with the percentage loading of UF6 on NaF pellets. The kinetic equation for the above process has been established for a particular size of NaF pellets and pellet porosity. (author)

  1. Studies on implementation of pellet tracking in hadron physics experiments

    Pyszniak A.

    2014-01-01

    Full Text Available A system for optical tracking of frozen hydrogen microsphere targets (pellets has been designed. It is intended for the upcoming hadron physics experiment PANDA at FAIR, Darmstadt, Germany. With such a tracking system one can reconstruct the positions of the individual pellets at the time of a hadronic interaction in the offline event analysis. This gives information on the position of the primary interaction vertex with an accuracy of a few 100 µm, which is very useful e.g. for reconstruction of charged particle tracks and secondary vertices and for background suppression. A study has been done at the WASA detector setup (Forschungszentrum Jülich, Germany to check the possibility of classification of hadronic events as originating in pellets or in background. The study has been done based on the instantaneous rate a Long Range TDC which was used to determine if a pellet was present in the accelerator beam region. It was clearly shown that it is possible to distinguish the two event classes. Also, an experience was gained with operation of two synchronized systems operating in different time scales, as it will also be the case with the optical pellet tracking.

  2. Characterization of grape pomace and pyrenean oak pellets

    One possibility for the elimination of the by-products generated in the viticulture industry can be their densification for subsequent use as a solid biofuel. In this work, washed grape pomace has been considered due to its thermal characteristics. Since it could show problems in the densification process, other by-products such as pyrenean oak residues, with good pelleting properties and available in this region, are also used. So that, samples of different concentrations from both residues were densified by means of a flat die pelletizer, obtaining pellets of 6 mm diameter. The densified samples were characterized in terms of the proximate and ultimate analyses, heating value and physical characteristics such as durability or bulk density. Also, the combustion profile of the pellets was studied by thermogravimetry and inorganic emissions such as sulphur dioxide and nitric oxide were considered, by means of coupled mass spectrometry (TG-MS). The results obtained showed that both residues show good characteristics for their densification and manufacture in pellets. Also, they show good physical and thermal properties for its use as biofuel, as well as its different blends. Therefore, it is possible to give a more efficient energetic use to both residues. (author)

  3. Characterization of grape pomace and pyrenean oak pellets

    Miranda, M.T.; Arranz, J.I.; Roman, S.; Rojas, S.; Montero, I.; Lopez, M.; Cruz, J.A. [Extremadura Univ., Badajoz (Spain). Dept. of Mechanical, Energetic and Materials Engineering

    2011-02-15

    One possibility for the elimination of the by-products generated in the viticulture industry can be their densification for subsequent use as a solid biofuel. In this work, washed grape pomace has been considered due to its thermal characteristics. Since it could show problems in the densification process, other by-products such as pyrenean oak residues, with good pelleting properties and available in this region, are also used. So that, samples of different concentrations from both residues were densified by means of a flat die pelletizer, obtaining pellets of 6 mm diameter. The densified samples were characterized in terms of the proximate and ultimate analyses, heating value and physical characteristics such as durability or bulk density. Also, the combustion profile of the pellets was studied by thermogravimetry and inorganic emissions such as sulphur dioxide and nitric oxide were considered, by means of coupled mass spectrometry (TG-MS). The results obtained showed that both residues show good characteristics for their densification and manufacture in pellets. Also, they show good physical and thermal properties for its use as biofuel, as well as its different blends. Therefore, it is possible to give a more efficient energetic use to both residues. (author)

  4. Pellet injector development at ORNL [Oak Ridge National Laboratory

    Advanced plasma fueling systems for magnetic confinement experiments are under development at Oak Ridge National Laboratory (ORNL). The general approach is that of producing and accelerating frozen hydrogenic pellets to speeds in the kilometer-per-second range by either pneumatic (light-gas gun) or mechanical (centrifugal force) techniques. ORNL has recently provided a centrifugal pellet injector for the Tore Supra tokamak and a new, simplified, eight-shot pneumatic injector for the Advanced Toroidal Facility stellarator at ORNL. Hundreds of tritium and DT pellets were accelerated at the Tritium Systems Test Assembly facility at Los Alamos in 1988--89. These experiments, done in a single-shot pipe-gun system, demonstrated the feasibility of forming and accelerating tritium pellets at low 3He levels. A new, tritium-compatible extruder mechanism is being designed for longer-pulse DT applications. Two-stage light-gas guns and electron beam rocket accelerators for speeds of the order of 2--10 km/s are also under development. Recently, a repeating, two-stage light-gas gun accelerated 10 surrogate pellets at a 1-Hz repetition rate to speeds in the range of 2--3 km/s; and the electron beam rocket accelerator completed initial feasibility and scaling experiments. ORNL has also developed conceptual designs of advanced plasma fueling systems for the Compact Ignition Tokamak and the International Thermonuclear Experimental Reactor

  5. Microstructure of gel-pelletized (ThU)O2

    ThO2-2% UO2 pellets, prepared from gel microspheres, should have a high density (> 94% T.D.) and a microstructure consisting of uniformly distributed porosity, mostly in the size range of 2 to 5 μm, and large grains (> 10 μm). However, the pellets often do not meet these requirements and are found to have a 'blackberry structure' due to densification only within and not between the microspheres during sintering. Different batches of press-feed microspheres, green pellets and sintered pellets were characterized by SEM, optical microscope and image analyzer. The gel microspheres containing ≅ 0.4% CaO sintering aid and ≅ 5% carbon black pore former on air-calcination at 973 K for 24 h led to soft and porous microspheres which could be easily compacted into pellets at 350 MPa (green density around 52% T.D.) and sintered to high density (> 94% T.D.) at 1773 K. (orig.)

  6. Blower Gun pellet injection system for W7-X

    Foreseen to serve for the new stellarator W7-X for pellet investigations, the former ASDEX Upgrade Blower Gun was revised and revitalized in a test bed. The gun is able now to launch cylindrical pellets of 2 mm diameter and 2 mm length, produced from frozen Deuterium (D2) or Hydrogen (H2). Pellets are accelerated by a short pulse of pressurized helium propellant gas to velocities in the range of 100-250 m/s. Delivery reliabilities at the launcher exit close to unity are achieved. For pellet transfer to the plasma vessel a first mock up guiding tube version was investigated. Transfer through this S-shaped (inner diameter 8 mm; length 6 m) stainless steel guiding tube containing two 1 m curvature radii was investigated for both H2 and D2 pellets. Tests were performed applying repetition rates from 2 Hz to 50 Hz and propellant gas pressures ranging from 1 bar to 6 bar. For both H2 and D2, low overall delivery efficiencies were observed at slow repetition rates, but stable efficiencies of about 90% above 10 Hz.

  7. Assessment of wood pellet combustion in a domestic boiler

    Wood pellet is a densified and homogeneous fuel to have better transport, storage and feeding capabilities than the original biomass for various domestic and industrial uses. A wood pellet boiler or stove needs to achieve complete combustion and high energy efficiency, which is often not easy for domestic application due to the design requirement for compact furnace and heat exchangers. This paper presents the design assessment of a 35 kW wood pellet boiler for domestic heating using experiments and computational fluid dynamic (CFD) simulations. For wood pellets with a lower heating value of 18 MJ/ kg and diameter 8 mm, the gas composition, temperatures and ash characteristics were measured from different parts of the boiler for various operational load, air flow rate and furnace configurations. The effects of other key parameters on the performance of the boiler were analyzed by CFD, which include furnace shapes, flow distribution and directions of secondary/ tertiary air. The results show that introducing simple measures to enhance gaseous mixing and reactions can greatly improve the combustion efficiency in a compact furnace. The findings can be applied to wood pellet boilers with difference capacities. (author)

  8. Particle transport in pellet fueled JET [Jet European Torus] plasmas

    Pellet fueling experiments have been carried out on the Joint European Torus (JET) tokamak with a multi-pellet injector. The pellets are injected at speeds approaching 1400 m/s and penetrate deep into the JET plasma. Highly peaked electron density profiles are achieved when penetration of the pellets approaches or goes beyond the magnetic axis, and these peaked profiles persist for more than two seconds in ohmic discharges and over one second in ICRF heated discharges. In this dissertation, analysis of electron particle transport in multi-pellet fueled JET limiter plasmas under a variety of heating conditions is described. The analysis is carried out with a one and one-half dimensional radial particle transport code to model the experimental density evolution with various particle transport coefficients. These analyses are carried out in plasmas with ohmic heating, ICRF heating, and neural beam heating, in limiter configurations. Peaked density profile cases are generally characterized by diffusion coefficients with a central (r/a 2/s that increases rapidly to ∼0.3 m2/s at r/a = 0.6 and then increases out to the plasma edge as (r/a)2. These discharges can be satisfactorily modeled without any anomalous convective (pinch) flux. 79 refs., 60 figs

  9. Radial voidage variation in fixed beds of fuel wood pellets

    Fixed beds of fuel wood are commonly found in numerous processes: storage and transportation, drying and thermal conversion such as combustion or gasification. Pellets in particular are mostly used as fuel for domestic heating boilers. The characterization of spatial voidage distribution is of great importance for flow and reactor modelling. The present study focuses on the radial porosity variations of cylindrical beds of commercially available wood pellets. The experimental procedure is based on the classical technique of consolidating packed beds with a resin. The radial voidage distribution of three different cylindrical beds is determined by image analysis of sections of the solidified packing. The results are discussed and summarized in a mathematical expression correlating the radial voidage distribution depending on packing core porosity and dimensionless distance from the tube wall. -- Highlights: ► Packing characteristics for commercially available wood pellets were investigated. ► Radial porosity variations of cylindrical pellets beds were investigated. ► Epoxy resin consolidated packings were investigated by image analysis. ► Mathematical term for radial voidage distribution of pellet packing was derived.

  10. The influence of compacting pressure on green pellet density in UO2 pelletizing process

    Generally compacting pressure on UO2 powder in pelletizing process can affect the green density. There are many correlation models presented this effect, derived from the basic phenomena and empiric (experiment) as well In the other hand, those correlation have many limitation on validation due to their assumptions, material conditions and equipment conditions as well. Based on those limitations this research was performed. It was performed with utilizing two different UO2 powder, i.e. UO2 powder resulted from granulation of pre-compacted powder with the compaction force of 2.5 tons, and the other with the compaction force of 3.0 tons. The compaction force was seven times variated within the range between five tons up to 18 tons, with ten replication for each. The green pellets wen visually observed to see the defect and their density were geometrically measured. The data were statistically proceed to prove the hypotheses and to formulate the correlation. The result showed that hypotheses was accepted. It resulted five correlations model formulas within the accepted range. Fifth correlation model showed better correlation than the others, and was able to describe tile phenomena of compaction process. It was a new model as an improvement on the forst model Although, this model had limited validation. It was only valid for compaction force in the range of 5 to 18 tons. The third and fourth models were able to describe the mechanical characteristic of material. It was prove by various comparation, and it complied with their phenomena. The obtained characteristic were strength of material and compressability factor

  11. Present and future trends in pellet markets, raw materials, and supply logistics in Sweden and Finland

    Wood pellets have become an important fuel in heat and power production, and pellet markets are currently undergoing rapid development. In this paper, the pellet markets, raw materials and supply structures are analyzed for Sweden and Finland, based on a database of the current location and production capacity of the pellet producers, complemented with existing reports and literature. In Sweden, a total of 94 pellet plants/producers were identified, producing 1.4 million tonnes of pellets, while the domestic consumption was 1.7 million tonnes, and about 400,000 t of pellets were imported to fulfil the demand in 2007. In Finland, 24 pellet plants/producers were identified and the production was around 330,000 t while the domestic consumption was 117,000 t in 2007. In Finland, pellet market has been long time export oriented, whereas domestic consumption has been growing mainly in the small scale consumer sector, estimated 15,000 households had pellet heating systems in 2008. In the future, the increasing number of pellet users will require a reliable delivery network and good equipment for bulk pellet deliveries. Provision of new raw materials and ensuring the good quality of pellets through the whole production, delivery and handling chain will be fundamental in order to increase the use of pellets and sustain the ability to compete with other fuels. (author)

  12. Present and future trends in pellet markets, raw materials, and supply logistics in Sweden and Finland

    Selkimaeki, Mari; Mola-Yudego, Blas [Finnish Forest Research Institute, Joensuu Research Unit, Yliopistokatu 6, P.O. Box 68, FI-80101 Joensuu (Finland); University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111 FI-80101 Joensuu (Finland); Roeser, Dominik; Prinz, Robert [Finnish Forest Research Institute, Joensuu Research Unit, Yliopistokatu 6, P.O. Box 68, FI-80101 Joensuu (Finland); Sikanen, Lauri [University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111 FI-80101 Joensuu (Finland)

    2010-12-15

    Wood pellets have become an important fuel in heat and power production, and pellet markets are currently undergoing rapid development. In this paper, the pellet markets, raw materials and supply structures are analyzed for Sweden and Finland, based on a database of the current location and production capacity of the pellet producers, complemented with existing reports and literature. In Sweden, a total of 94 pellet plants/producers were identified, producing 1.4 million tonnes of pellets, while the domestic consumption was 1.7 million tonnes, and about 400,000 t of pellets were imported to fulfil the demand in 2007. In Finland, 24 pellet plants/producers were identified and the production was around 330,000 t while the domestic consumption was 117,000 t in 2007. In Finland, pellet market has been long time export oriented, whereas domestic consumption has been growing mainly in the small scale consumer sector, estimated 15,000 households had pellet heating systems in 2008. In the future, the increasing number of pellet users will require a reliable delivery network and good equipment for bulk pellet deliveries. Provision of new raw materials and ensuring the good quality of pellets through the whole production, delivery and handling chain will be fundamental in order to increase the use of pellets and sustain the ability to compete with other fuels. (author)

  13. Control System of Pellet Injector on the HT-7 Tokamak

    2001-01-01

    In this paper the control system of the pellet injector is introduced in detail and the system mainly includes two parts: the present and the remote control system. The present control system controls the injector and provides the interface to the remote system. And the remote control system has acquired present signals with analog input card and perform the actions through digit output card, it also has an interface for Windows programming easily used by the operators when carrying out the pellet injection experiments. Through several HT-7 campaigns, the remote control system has been validated to be feasible and reliable and has made successful shots for studying the interactions between the pellets and plasma.

  14. 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. Preliminary results were described in Riso-M-2536 and in Riso-M-2650. This final report describes the work carried out from 1987.03.31 to 1988.09.30. An arc heated hydrogen gas source, for pneumatic acceleration of deuterium pellets to velocities above 2 km/s, was developed. Experiments were performed with an arc chamber to which different methods of hydrogen supply were possible, and to which the input of electrical power could be programmed. Results in terms of pressure transients and acceleration curves are presented. Maximum pellet velocities approaching 2 km/s were obtained. This limit is discussed in relation to the presented data. Finally this report contains a summary and a conclusion for the entire project. (author) 34 ills., 3 refs

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

    American Society for Testing and Materials. Philadelphia

    2001-01-01

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

  16. Upper bound to the thermal conductivity of carbon nanotube pellets

    Chalopin, Yann; Volz, Sebastian; Mingo, Natalio

    2009-04-01

    Using atomistic Green's function calculations, we find that the phonon thermal conductivity of pellets composed of ˜μm long carbon nanotubes has an upper bound of a few W/m K. This is in striking contrast with the extremely high thermal conductivity of individual nanotubes (˜3000 W/m K). We show that, at room temperature, this upper bound does not depend on the nanotube diameter. Conversely, for low temperatures, an inverse proportionality with nanotube diameter is predicted. We present concrete results as a function of nanotube length and chirality, pellet density, and temperature. These results imply that carbon nanotube pellets belong to the category of thermal insulators, contrasting with the good conducting properties of parallel nanotube arrays, or individual nanotubes.

  17. FORMULATION AND EVALUATION OF SUSTAINED RELEASE PELLETS OF TRAMADOL HYDROCHLORIDE

    Baskara Haripriya

    2013-02-01

    Full Text Available The aim of the present research is to develop and evaluate a better sustained release multiple unit pellets (MUP formulation of Tramadol hydrochloride. Dissolution and diffusion controlled systems have classically been of primary importance in oral delivery of medication because of their relative ease of production and cost compared with other methods of sustained or controlled delivery. Most of these systems are solids, although a few liquids and suspension have been recently introduced. The present work aimed at developing SR pellets of Tramadol HCl by Wurster process. FTIR studies showed no unacceptable extra peaks which confirm the absence of chemical interaction between the drug and polymer. Angle of repose, tapped density, bulk density values for the formulations were within the range which indicates that pellets prepared by Wurster process were satisfactory for further studies. The percentage drug content of Tramadol was determined by extraction with methanol and analyzed by using UV-visible spectrophotometer at 271nm.

  18. Blood concentrations of chlortetracycline in macaws fed medicated pelleted feed.

    Flammer, K; Cassidy, D R; Landgraf, W W; Ross, P F

    1989-01-01

    A trial was conducted to determine the suitability of using a pelleted diet containing chlortetracycline (CTC) for treatment of chlamydiosis in macaws. Macaws, normally fed seed and fruit diets in captivity, are notoriously difficult to treat with CTC-medicated mash diets. Healthy macaws fed a pelleted diet containing 1% or 1.5% CTC for 30 or 45 days maintained adequate food intake and mean blood concentrations of 1-2 CTC micrograms/ml blood throughout the treatment period. There were no significant differences between blood concentrations induced by the different dietary CTC concentrations. Blood concentrations of 1 microgram/ml are considered therapeutic, so it is likely that 1% CTC-medicated pellets will be adequate for treating chlamydiosis in these species. PMID:2930403

  19. Pellet wood gasification boiler / Combination boiler. Market review. 7. ed.; Scheitholzvergaser-/Kombikessel. Marktuebersicht

    Uth, Joern

    2010-08-15

    In the market review under consideration on pellet wood gasification boilers and combination boilers, the Federal Ministry of Food, Agriculture and Consumer Protection (Bonn, Federal Republic of Germany) report on planning and installation of wood-fired heating systems, recommendations regarding to the technical assessment of boiler systems, buffers/combination boilers, prices of pellet wood gasification boilers, data sheets of the compared pellet wood gasification boilers, pellet wood combination boilers, prices of pellet wood combination boilers, data sheets of the compared pellet wood gasification boilers, list of providers.

  20. Market review. Pellet wood gasification boiler / combination boiler. 8. ed.; Marktuebersicht. Scheitholzvergaser-/Kombikessel

    Uth, Joern

    2012-01-15

    In the market review under consideration on pellet wood gasification boilers and combination boilers, the Federal Ministry of Food, Agriculture and Consumer Protection (Bonn, Federal Republic of Germany) reports on planning and installation of wood-fired heating systems, recommendations regarding to the technical assessment of boiler systems, buffers/combination boilers, prices of pellet wood gasification boilers, data sheets of the compared pellet wood gasification boilers, pellet wood combination boilers, prices of pellet wood combination boilers, data sheets of the compared pellet wood gasification boilers, list of providers.

  1. STUDY OF THE INFLUENCE OF COMPLEMENTARY HYDRATION ON THE MECHANICAL PROPERTIES OF SELF-REDUCING PELLETS

    Felippe de Oliveira Sousa

    2015-06-01

    Full Text Available This study has investigated how different methods and time of complementary hydration affects the cold strength of self-reducing pellets. Identical pellets had been made by the addition of pellet feed, coal, cement and lime and have been subjected to hydration by water immersion or in a moist chamber for different periods. A group of non-hydrated pellets was used as reference for evaluation the effect of hydration. The pellets were then characterized by mechanical tests of compression and tumbling strength. The results have shown an increase in the mechanical properties of pellets and have proved that the hydration by moist chamber was the most efficient method.

  2. A new centrifuge pellet injector with a screw extruder for steady state fuelling

    A new conceptual design of a centrifuge injector for steady state plasma refuelling by solid hydrogen isotope pellets is presented and discussed. The apparatus has three new components: a screw extruder for continuous pellet production, a new rotating curved barrel for pellet acceleration, whose entrance section is placed on the axis of the centrifuge rotor, and a new pellet chopping unit. In preliminary tests, the screw extruder with the pellet chopping unit delivered a series of about 10,000 deuterium pellets of 2 mm in size (at the range up to 15 Hz and velocities 100-150 m/s) into the curved barrel with a 99% reliability. (author)

  3. Formation of particulate matter monitoring during combustion of wood pellete with additives

    Palacka, Matej; Holubčík, Michal; Vician, Peter; Jandačka, Jozef

    2016-06-01

    Application additives into the material for the production of wood pellets achieve an improvement in some properties such as pellets ash flow temperature and abrasion resistance. Additives their properties influence the course of combustion, and have an impact on the results of issuance. The experiment were selected additives corn starch and dolomite. Wood pellets were produced in the pelleting press and pelletizing with the additives. Selected samples were tested for the production of particulate matter (PM) during their direct burn. The paper analyzing a process of producing wood pellets and his effect on the final properties.

  4. Can adult and juvenile European rabbits be differentiated by their pellet sizes?

    Delibes-Mateos, Miguel; Rouco, Carlos; Villafuerte, Rafael

    2009-03-01

    Recently, a new method for differentiating juvenile and adult rabbits based on faecal pellet size was published. According to this method, pellets >6 mm diameter are inferred to be deposited by adults, while those test the accuracy of this methodology. Twelve adult rabbits were housed in individual outdoor cages and their pellets were removed every day for 10 consecutive days. Pellets were separated using a sieve according to their size and counted. Results showed that adult rabbits produce pellets >6 mm diameter in the same proportion as those 6 mm, whereas others deposit mostly pellets animals in the absence of validating studies.

  5. Initial performance and characteristics of the PBX-M pellet injector

    The Princeton Beta Experiment-Modified (PBX-M) Pellet Injector Project provides for the fabrication, installation and operation of a pellet injector fueling system on the PBX-M tokamak experiment. The system consists of an eight barrel pellet gun, a pellet transport facility and a control system. The gun is an eight-shot pneumatic assembly designed and fabricated at the Oak Ridge National Laboratory (ORNL). The pellet transport and control facilities were designed, fabricated and installed by Princeton Plasma Physics Laboratory (PPPL). The integrated pellet injector system has been installed on PBX-M and is operational for use in plasma experiments. 1 ref., 7 figs

  6. Pellet production from agricultural raw materials - A systems study

    Nilsson, Daniel; Bernesson, Sven; Hansson, Per-Anders [Department of Energy and Technology, Swedish University of Agricultural Sciences, P.O. Box 7032, SE-75007 Uppsala (Sweden)

    2011-01-15

    The demand for biofuel pellets has increased considerably in recent years, causing shortage of the traditional raw materials sawdust and wood shavings. In this study, the costs and energy requirements for the production of pellets from agricultural raw materials were analysed. The materials studied were Salix, reed canary grass, hemp, straw, screenings, rape-seed meal, rape cake and distiller's waste. Four production scales were analysed, having an annual output of 80,000, 8000, 800 and 80 tonnes of pellets per year. It was concluded that the raw materials of greatest interest were Salix and reed canary grass. They had competitive raw material costs and acceptable fuel properties and could be mixed with sawdust in existing large-scale pelleting factories. Straw had low production costs but can cause serious ash-related problems and should, as also is the case for screenings, be avoided in small-scale burners. Hemp had high raw material costs and is of less commercial interest, while distiller's waste, rape-seed meal and rape cake had higher alternative values when used as protein feed. The scale of production had a crucial influence on production costs. The machinery was used much more efficiently in large-scale plants, resulting in clear cost savings. Small-scale pelleting, both static and mobile, required cheap raw materials, low labour costs and long utilisation times to be profitable. In most cases, briquetting would be more commercially viable. The energy use in manufacturing pellets from air-dried crops was generally no higher than when moist sawdust was used as the raw material. (author)

  7. Control System for the NSTX Lithium Pellet Injector

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

    2003-10-27

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

  8. Control System for the NSTX Lithium Pellet Injector

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

  9. Nonisothermal Behavior of Oxidation of Natural Ilmenite Pellet

    2000-01-01

    The nonisothermal behavior of the oxidation of natural ilmenite pellets was interpreted in the light of a nonisothermal kinetic model which fits the experimental results very well.The rate of the overall oxidation was predominantly controlled by the intrapellet diffusion of oxygen and the rate of heat transfer was mainly limited by the heat conduction through the product layer.The oxidation of natural ilmenite pellet can not be treated as an isothermal reaction system within the temperature range of 1073~ 1173K unless the concentration of oxygen in the gaseous reactants is less than 10 mol%.

  10. Modelling of pellet-cladding interaction in PWR's

    The pellet-cladding interaction that can occur in a PWR fuel rod design is modelled with the computer codes FRAPCON-1 and ANSYS. The fuel performance code FRAPCON-1 analyses the fuel rod irradiation behavior and generates the initial conditions for the localized fuel rod thermal and mechanical modelling in two and three-dimensional finite elements with ANSYS. In the mechanical modelling, a pellet fragment is placed in the fuel rod gap. Two types of fuel rod cladding materials are considered: Zircaloy and austenitic stainless steel. (author)

  11. First in China Caprolactam Pelletizing Line Put on Stream

    2008-01-01

    @@ In August 2008 the caprolactam palletizing section at the Shijiazhuang Chemical Fiber Company was put on stream successfully at the first attempt during feeding of process streams. It is told that this is the only one caprolactam pel-letizing facility in China, which is imported from Germany rated at a production capacity of 56 kt/a. Compared to the caprolactam chips, the caprolactam pellets are not prone to moisture pickup and oxidation and can improve the packag-ing environment thanks to its minor amount of pulverized fines to fundamentally prevent safety hazards.

  12. Quality of Pelleted Olive Cake for Energy Generation

    Tea Brlek

    2014-02-01

    Full Text Available Normal 0 21 false false false SR X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Olive cake is by-product of olive oil production. This material cannot be stored in original condition for a long time because it has high water content and relatively high portion of oil that causes rapid deterioration. Thus it is necessary to investigate possible methods of remediation of such by-product, where utilization for energy generation presents a useful option. Several studies have been conducted on energy generation from olive cake, however not one that includes pelleting as a pre-treatment. Therefore, the aim of this paper was to determine the chemical composition of different cultivars of olive cake, to produce pellets, and determine their basic quality parameters. The pellets obtained from olive cake had mainly satisfactory results regarding their quality in comparison to standards for fuel pellets. It should be kept in mind that these standards are manly for wood pellets, and therefore some lower criteria could be applied for olive cake and such biomass. The highest amount of residual oil and the lowest amount of protein was found in cultivar ‘Buža’ and produced pellets had the smallest abrasion index (8.15%. Other cultivars had lower oil and higher protein content, and abrasion index

  13. Vision guided robotic handling for density measurement of fuel pellets

    Handling and inspection of fuel pellets are routine requirements in nuclear fuel fabrication facilities. In order to minimize human exposure to hazards of radioactivity and to eliminate worker involvement in repetitive and monotonous tasks, it is desirable to deploy robots to perform these tasks. A robot-based system is potentially safe, reliable, consistent and accurate in measurements compared to a manually managed system. This paper describes the development of a vision guided robotic system for the measurement of density of fuel pellets. The system is capable of locating, picking, placing and finally computing density by using immersive technique. (author)

  14. Implantation of methodology for determination of fluorine and chlorine contents in fuel pellets by pyrohydrolysis at CDTN-MG (Brazil); Implantacao no CDTN de metodologia para determinacao de teores de fluor e de cloro em pastilhas combustiveis atraves de pirohidrolise

    Ferreira, Ricardo Alberto Neto; Avelar, Marta Maria; Morais, Carlos Antonio de; Lula, Zilmar Lima; Silva, Luiz Carlos da [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)]. E-mail: ranf@cdtn.br; avelarm@cdtn.br; cmorais@cdtn.br; zlula@cdtn.br; lcs@cdtn.br

    2005-07-01

    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)

  15. Insight into magnetorheological shock absorbers

    Gołdasz, Janusz

    2015-01-01

    This book deals with magnetorheological fluid theory, modeling and applications of automotive magnetorheological dampers. On the theoretical side a review of MR fluid compositions and key factors affecting the characteristics of these fluids is followed by a description of existing applications in the area of vibration isolation and flow-mode shock absorbers in particular. As a majority of existing magnetorheological devices operates in a so-called flow mode a critical review is carried out in that regard. Specifically, the authors highlight common configurations of flow-mode magnetorheological shock absorbers, or so-called MR dampers that have been considered by the automotive industry for controlled chassis applications. The authors focus on single-tube dampers utilizing a piston assembly with one coil or multiple coils and at least one annular flow channel in the piston.

  16. Optical trapping of absorbing particles

    Rubinsztein-Dunlop, H; Friese, M E J; Heckenberg, N R

    1998-01-01

    Radiation pressure forces in a focussed laser beam can be used to trap microscopic absorbing particles against a substrate. Calculations based on momentum transfer considerations show that stable trapping occurs before the beam waist, and that trapping is more effective with doughnut beams. Such doughnut beams can transfer angular momentum leading to rotation of the trapped particles. Energy is also transferred, which can result in heating of the particles to temperatures above the boiling point of the surrounding medium.

  17. Optical trapping of absorbing particles

    Rubinsztein-Dunlop, H.; Nieminen, T. A.; Friese, M. E. J.; Heckenberg, N R

    2003-01-01

    Radiation pressure forces in a focussed laser beam can be used to trap microscopic absorbing particles against a substrate. Calculations based on momentum transfer considerations show that stable trapping occurs before the beam waist, and that trapping is more effective with doughnut beams. Such doughnut beams can transfer angular momentum leading to rotation of the trapped particles. Energy is also transferred, which can result in heating of the particles to temperatures above the boiling po...

  18. In-Reactor Densification of Dual Cooled Annular Fuel Pellet during Irradiation Test at HANARO

    Rhee, Young Woo; Kim, Dong Joo; Kwon, Hyoung Mun; Kim, Keon Sik; Kim, Jong Hun; Oh, Jang Soo; Yang, Jae Ho; Koo, Yang Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    These advantages result in a considerably low pellet centerline temperature. Because of this considerably low pellet temperature, in-reactor behavior of an annular pellet, such as densification and swelling may be significantly different from that of the conventional PWR solid pellet. Since the pellet temperature of an annular fuel rod is lower than that of a PWR solid fuel rod by several hundred degrees, the in-reactor densification and swelling of a dual cooled annular fuel pellet might be considered as athermal phenomena due to a low pellet temperature. In order to investigate the in-reactor behavior of the annular UO{sub 2} pellet, HANARO irradiation test was planned and conducted for annular pellets with 5 different types. Post irradiation test is being carried out in the KAERI's PIE facility. In this study, we are going to report the preliminary results of PIE test on the inreactor densification behavior of a dual cooled annular fuel pellet. Irradiation test of dual cooled annular UO{sub 2} pellet was conducted at the OR-4 hole in HANARO by using a non-instrumented test rig. The preliminary results of PIE test on the in-reactor densification behavior showed that the irradiated pellets densified much more than expected values based on MATPRO relations of inreactor densification at low temperature in the annular pellet with low initial sintered density. It might be attributed to the higher fission rate during HANARO irradiation.

  19. ELM mitigation with pellet ELM triggering and implications for PFCs and plasma performance in ITER

    Baylor, L.R., E-mail: BaylorLR@ornl.gov [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37830-8050 (United States); Lang, P.T. [Max Plank Institute für Plasmaphysik, EURATOM Association., Boltzmannstr. 2, 85748 Garching (Germany); Allen, S.L. [Lawrence Livermore National Laboratory, 700 East Ave, Livermore, CA 94550 (United States); Combs, S.K.; Commaux, N. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37830-8050 (United States); Evans, T.E. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Fenstermacher, M.E. [Lawrence Livermore National Laboratory, 700 East Ave, Livermore, CA 94550 (United States); Huijsmans, G. [ITER Organization, CS 90 046, 13067 St. Paul lez Durance Cedex (France); Jernigan, T.C. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37830-8050 (United States); Lasnier, C.J. [Lawrence Livermore National Laboratory, 700 East Ave, Livermore, CA 94550 (United States); Leonard, A.W. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Loarte, A. [ITER Organization, CS 90 046, 13067 St. Paul lez Durance Cedex (France); Maingi, R. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Maruyama, S. [ITER Organization, CS 90 046, 13067 St. Paul lez Durance Cedex (France); Meitner, S.J. [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37830-8050 (United States); Moyer, R.A. [University of California San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0417 (United States); Osborne, T.H. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States)

    2015-08-15

    The triggering of rapid small edge localized modes (ELMs) by high frequency pellet injection has been proposed as a method to prevent large naturally occurring ELMs that can erode the ITER plasma facing components (PFCs). Deuterium pellet injection has been used to successfully demonstrate the on-demand triggering of edge localized modes (ELMs) at much higher rates and with much smaller intensity than natural ELMs. The proposed hypothesis for the triggering mechanism of ELMs by pellets is the local pressure perturbation resulting from reheating of the pellet cloud that can exceed the local high-n ballooning mode threshold where the pellet is injected. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of high-n ballooning modes by such a local pressure perturbation. A review of the recent pellet ELM triggering results from ASDEX Upgrade (AUG), DIII-D, and JET reveals that a number of uncertainties about this ELM mitigation technique still remain. These include the heat flux impact pattern on the divertor and wall from pellet triggered and natural ELMs, the necessary pellet size and injection location to reliably trigger ELMs, and the level of fueling to be expected from ELM triggering pellets and synergy with larger fueling pellets. The implications of these issues for pellet ELM mitigation in ITER and its impact on the PFCs are presented along with the design features of the pellet injection system for ITER.

  20. Pellet market, raw materials, handling and logistics in Northern Periphery. PELLETime

    Selkimaeki, M.; Prinz, R.; Mola-Yudego, B.; Roeser, D. email: dominik.roser@metla.fi

    2010-07-01

    Wood pellets have become an important fuel in heat and power production. The pellet market and supply structures are currently undergoing rapid development. Ensuring the quality of pellets through the whole production, delivery and handling chain is important in order to increase the use of pellets and sustain its ability to compete with other fuels. This study focuses on the development of the pellet market, raw materials and supply structures mainly in Sweden and Finland. Sweden has a highly developed pellet market, where fuel taxation has promoted the use of wood pellets especially in large scale boilers of >2MW, where more than half of the pellets are combusted. There are about 120 000 households using pellet heating systems in addition to the 20 000 households using pellet stoves. Sweden is the world's largest producer and consumer of pellets. In 2007 a total of 94 pellet plants/producers were producing 1.4 million tonnes of pellets, while at the same time the consumption was 1.7 million tonnes. In addition, about 400 000 tonnes of pellets were imported to meet domestic demand. In Finland, pellet production has been growing steadily despite the fact that domestic consumption has remained relatively small until recently. Today there are 24 pellet plants/producers. In 2007 production was around 330 000 tonnes while the domestic consumption was 117 000 tonnes. The pellet market in Finland has long been export oriented; with 75% and 58% of production being exported in 2006 and 2007, respectively. Domestic consumption has been growing mainly in the small scale consumer sector; it is estimated that 15 000 households had pellet heating systems in 2008. Concerning supply structures, Sweden has well established pellet distribution networks, for domestic household consumers pellets are mainly delivered in sacks (80%) directly from the plant or through extensive network of retailers while bulk deliveries are less common (20%). In Finland pellets are delivered to

  1. Comments on Pellet Ablation in Hot Plasmas and the Problem of Magnetic Shielding

    Chang, C. T.

    1979-01-01

    Clarifications are provided concerning the consistency of a previously formulated magnetic nozzle model in connection with pellet ablation.......Clarifications are provided concerning the consistency of a previously formulated magnetic nozzle model in connection with pellet ablation....

  2. Pellet manufacturing by extrusion-spheronization using process analytical technology

    Sandler, Niklas; Rantanen, Jukka; Heinämäki, Jyrki;

    2005-01-01

    the active pharmaceutical ingredients (APIs) during pelletization. Raman spectroscopy, near-infrared (NIR) spectroscopy, and X-ray powder diffraction (XRPD) were used in the characterization of polymorphic changes during the process. Samples were collected at the end of each processing stage (blending...

  3. Assessment of Biomass Pelletization Options for Greensburg, Kansas

    Haase, S.

    2010-05-01

    This report provides an overview of a technical report on an assessment NREL conducted in Greensburg, Kansas, to identify potential opportunities to develop a biomass pelletization or briquetting plant in the region. See NREL/TP-7A2-45843 for the Executive Summary of this report.

  4. Model analysis for combustion characteristics of RDF pellet

    2002-01-01

    Fundamental studies of the combustion characteristics and the de-HCl behavior of a single refuse-derived fuel(RDF) pellet were carried out to explain the de-HCl phenomena of RDF during fluidized bed combustion and to provide data for the development of high efficiency power generation technology using RDF previously. For further interpreting the devolatilization and the char combustion processes of RDF quantitatively, an unsteady combustion model for single RDF pellet, involving reaction rates, heat transfer and oxygen diffusion in the RDF pellet, was developed. Comparisons of simulation results with experimental data for mass loss of the RDF samples made from municipal solid waste, wood chips and poly-propylene when they were heated at 10K/min or put into the furnace under 1073K show the verifiability of the model. Using this model, the distributions of the temperature and the reaction ratio along the radius of RDF pellet during the devolatilization process and the char combustion process were presented, and discussion about the inference of heating rate on the combustion characteristics were performed.

  5. USE OF PELLETED LETTUCE SEEDS IN BIOABAILABILITY STUDIES

    Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. Th...

  6. USE OF PELLETED LETTUCE SEEDS IN BIOAVAILABILITY STUDIES

    Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. Th...

  7. Reprint of: Pelletizing properties of torrefied wheat straw

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

  8. Analytical model of neutral gas shielding for hydrogen pellet ablation

    Kuteev, Boris V.; Tsendin, Lev D. [State Technical Univ., St. Petersburg (Russian Federation)

    2001-11-01

    A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dR{sub pe}/dt{approx}S{sub n}{sup 2/3}R{sub p}{sup -2/3}q{sub eo}{sup 1/3}m{sub i}{sup -1/3} is confirmed. Here R{sub p} is the pellet radius, S{sub n} is the optical thickness of a cloud, q{sub eo} is the electron energy flux density and m{sub i} is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)

  9. ANALYSIS OF THERMAL-CHEMICAL CHARACTERISTICS OF BIOMASS ENERGY PELLETS

    Zorica Gluvakov

    2014-09-01

    Full Text Available In modern life conditions, when emphasis is on environmental protection and sustainable development, fuels produced from biomass are increasingly gaining in importance, and it is necessary to consider the quality of end products obtained from biomass. Based on the existing European standards, collected literature and existing laboratory methods, this paper presents results of testing individual thermal - chemical properties of biomass energy pellets after extrusion and cooling the compressed material. Analysing samples based on standard methods, data were obtained on the basis of which individual thermal-chemical properties of pellets were estimated. Comparing the obtained results with the standards and literature sources, it can be said that moisture content, ash content and calorific values are the most important parameters for quality analysis which decide on applicability and use-value of biomass energy pellets, as biofuel. This paper also shows the impact of biofuels on the quality of environmental protection. The conclusion provides a clear statement of quality of biomass energy pellets.

  10. Thermal characterization of (U, Dy)O2 pellets

    The thermal diffusivity of (U,Dy)O2 pellets were determined in the temperature range 250 K to 1600 K measured by the laser flash method. The dependence of thermal with temperature and dysprosium content was studied and found in good agreement with physical models available (author)

  11. Analytical model of neutral gas shielding for hydrogen pellet ablation

    A kinetic gasdynamic scaling for hydrogen pellet ablation is obtained in terms of a neural gas shielding model using both numerical and analytical approaches. The scaling on plasma and pellet parameters proposed in the monoenergy approximation by Milora and Foster dRpe/dt∼Sn2/3Rp-2/3qeo1/3mi-1/3 is confirmed. Here Rp is the pellet radius, Sn is the optical thickness of a cloud, qeo is the electron energy flux density and mi is the molecular mass. Only the numeral factor is approximately two times less than that for the monoenergy approach. Due to this effect, the pellet ablation rates, which were obtained by Kuteev on the basis of the Milora scaling, should be reduced by a factor of 1.7. Such a modification provides a reasonable agreement (even at high plasma parameters) between the two-dimensional kinetic model and the one-dimensional monoenergy approximation validated in contemporary tokamak experiments. As the could (in the kinetic approximation) is significantly thicker than that for the monoenergy case as well as the velocities of the gas flow are much slower, the relative effect of plasma and magnetic shielding on the ablation rate is strongly reduced. (author)

  12. Standard specification for nuclear-Grade boron carbide pellets

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This specification applies to boron carbide pellets for use as a control material in nuclear reactors. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

  13. Impurity injection by use of multiple-shell pellet

    A model of the three-layered multiple-shell pellet is studied in order to apply to the impurity injection experiment. The mass dependence of the ablation is examined by employing the neutral-cloud shielding model. The localization width of the impurity is estimated. (author)

  14. Small-Scale Pellet Heating Systems from Consumer Perspective

    A questionnaire survey of 1,500 detached house owners was carried out in the autumn of 2004 to find out the factors influencing the adoption and diffusion of pellet heating systems in the Swedish residential sector. The results revealed that most of the respondents had no plans to install new heating systems as they were satisfied with their existing ones. Economic aspects and functional reliability were the most important factors in the respondents' choice of heating system while environmental factors were of less importance. Therefore, internalizing external costs, such as environmental costs, might be effective in influencing house owners to adopt environmentally benign heating systems. Installers were the most important source of information on heating systems. Hence, it is important that they could inform the consumers comprehensively and accurately about different heating systems. Respondents perceived the relative advantage of pellet boilers over oil or electricity-based heating systems, but bedrock heat pump system was ranked higher than pellet heating system in every aspect except for investment cost. Pellet heating system has advantage over district heating system with respect to investment cost and annual cost of heating. District heating system was considered as most functionally reliable and automatic

  15. quality assurance calculation in UO2 pellet manufacturing process

    A process qualification plan is prepared for preparation of quality assurance documentation in accordance with ISO-9000 series of standards, for sintered UO2 pellets manufactured in the Nuclear Fuel Technology Department. The objectives of this plan are to determine quantitatively and statistically process capability of the pellet production, to check product properties (are) in conformance with specifications at the pre-( ) confidence levels, to prepare necessary documents and to assess the results. The product properties taking into account are chemical composition, cracks, density, microstructure and grain size. The statistical parameters used for qualification element of quality assurance are calculated.Statistical values for sintered pellets are: LENGTH/WEIGHT/DIAMETER/DENSITY/%TD: MEAN:13,395/16,808/12,293/10,679/97,400 STD:0,1651/ 0,252/0,0212/0,015/0,140. It was seen that sintered pellets manufactured in the Nuclear Fuel Technology Department meet the criteria within 95% confidence level. In this paper specifications, criteria and calculations will be explained in detail

  16. Automatic failure identification of the nuclear power plant pellet fuel

    This paper proposed the development of an automatic technique for evaluating defects to help in the stage of fabrication of fuel elements. Was produced an intelligent image analysis for automatic recognition of defects in uranium pellets. Therefore, an Artificial Neural Network (ANN) was trained using segments of histograms of pellets, containing examples of both normal (no fault) and of defectives pellets (with major defects normally found). The images of the pellets were segmented into 11 shares. Histograms were made of these segments and trained the ANN. Besides automating the process, the system was able to obtain this classification accuracy of 98.33%. Although this percentage represents a significant advance ever in the quality control process, the use of more advanced techniques of photography and lighting will reduce it to insignificant levels with low cost. Technologically, the method developed, should it ever be implemented, will add substantial value in terms of process quality control and production outages in relation to domestic manufacturing of nuclear fuel. (author)

  17. DEVELOPMENT AND EVALUATION OF CLOZAPINE PELLETS FOR CONTROLLED RELEASE

    D.V. Gowda

    2012-08-01

    Full Text Available This research work was done to design oral controlled release matrix pellets of water insoluble drug Clozapine, using blend of Hydroxypropyl cellulose and glyceryl palmito stearate as as matrix polymers, methyl crystalline cellulose as spheronizer enhancer,sodium lauryl sulphate as pore forming agent. Clozapine formulations developed by the pellitization technique by drug loaded pellets were characterized with regard to the drug content, size distribution, Scanning electron microscopy, differential scanning calorimetry, fourier transform infrared spectroscopy and Xray Diffraction study. Stability studies were carried out on the optimized formulation for aperiod of 90 days, 40 ± 2 oC and 75 ± 5% relative humidity. The drug content was in the range of 95.34 – 98.12 %. The mean particle size of drug loaded pellets was in the range 1018 to 1065 mm. SEM photographs and calculated sphericity factor confirms that the prepared formulations were spherical in nature. The drug loaded pellets were stable and compatible as confirmed by DSC and FTIR studies. XRD patterns revealed the crystalline nature of pure clozapine. Loose surface crystal study indicated that crystalline clozapine was observed in all formulation and more clear in formulation A5. Higher amount of clozapine released was observed from formulation A5 and Syclop® 25 mg tablet as compared to all other formulations and mechanism of drug release followed Fickian diffusion. It can be concluded that formulation A5 is an ideal formulation for once a day administration.

  18. High-performance supershots in TFTR with lithium pellet injection

    Increasing the amount of lithium pellet injection during the supershot conditioning procedures has enabled reliable enhancement of supershot confinement at higher plasma currents. Some shots have exceptionally good performance, with peak global parameters up to τE=205 ms, Sn=5.6 x 1016n/s and QDD=2. 1 x 10-3

  19. The Magnetic Shielding Effect of a Re-Fuelling Pellet

    Chang, C. T.

    1975-01-01

    The magnetic shielding effect of a refuelling pellet is considered by first briefly reviewing the existing balloon model. The limitation of the model is pointed out and discussed. Since solid deuterium is an insulator and the ablated plasma is expected to be cold and dense, it is felt that the ex...

  20. The sensitivity theory for inertial confinement pellet fusion system

    A sensitivity theory for inertial confinement pellet fusion system is developed based on a physical model similar to that embodied in the laser fusion code MEDUSA. The theory presented here can be an efficient tool for estimating the effects of many alternations in the data field. Our result is different from Greenspan's work in 1980. (author)

  1. Glueing of solar absorbers; Solarabsorber kleben

    Berner, Joachim

    2012-04-20

    Bonding technologies in absorber fabrication are evolving. After soldering, ultrasonic welding and laser welding, glueing is the latest development. The Go Innovate AG company developed a process for glueing the most varied absorber materials.

  2. Combustion Gases And Heat Release Analysis During Flame And Flameless Combustion Of Wood Pellets

    Horváth Jozef; Wachter Igor; Balog Karol

    2015-01-01

    With the growing prices of fossil fuels, alternative fuels produced of biomass come to the fore. They are made of waste materials derived from the processing of wood and wood materials. The main objective of this study was to analyse the fire-technical characteristics of wood pellets. The study analysed three dust samples acquired from wood pellets made of various types of wood biomass. Wood pellet dust is produced when manipulating with pellets. During this process a potentially hazardous si...

  3. Characterization of Fe/KClO4 heat powders and pellets.

    Reinhardt, Frederick William; Guidotti, Ronald Armand; Odinek, Judy Gail

    2005-04-01

    Pellets of Fe/KClO{sub 4} mixtures are used as a heat source for thermally activated ('thermal') batteries. They provide the energy necessary for melting the electrolyte and bringing the battery stack to operating temperature. The effects of morphology of the Fe and the heat-pellet density and composition on both the physical properties (flowability, pelletization, and pellet strength) and the pyrotechnic performance (burn rate and ignition sensitivity) were examined using several commercial sources of Fe.

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

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

    2014-05-01

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

  5. Performance of a domestic pellet boiler as a function of operational loads: Part-2

    Verma, V.K.; De Ruyck, J. [Department Mechanical Engineering, Faculty of Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel (Belgium); Bram, S. [Department Mechanical Engineering, Faculty of Engineering, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel (Belgium); Department of Industrial Sciences and Technology, Erasmushogeschool Brussel, Nijverheidskaai 170, 1070 Brussel (Belgium); Gauthier, G. [Unite de Thermodynamique et Turbomachines (TERM), Universite Catholique de Louvain (U.C.L.), 1348 Louvain-la-Neuve (Belgium)

    2011-01-15

    Emissions and efficiency of a pellet boiler (40 kW) at nominal load were compared with emissions and efficiency at reduced load, while fired with six biomass pellets. The pellets include reed canary grass (Phalaris arundinacea), pectin waste from citrus shells (Citrus reticulata), sunflower husk (Helianthus annuus), peat, wheat straw (Triticum aestivum) and wood pellets. The measurements of emissions comprised of carbon monoxide (CO), nitrogen oxides (NO{sub x}), sulphur oxides (SO{sub x}) and flue dust mass concentrations (using DINplus and isokinetic sampling techniques). Emissions varied as a function of operational loads, for each type of pellets. The CO emissions were insignificant with reed canary grass (RCG), citrus pectin waste (CPW) and straw pellets at nominal load, however, at reduced load same pellets emitted 1.9, 4.0 and 7.4 times higher CO than wood pellets, respectively. Peat pellets emitted maximum CO at nominal load (4221.1 mgNm{sup -3}, 12.6 times higher than wood pellets) however; at reduced load CO emission was insignificant. The highest NO{sub x} emissions were reported with CPW, which were 3.4 and 4.6 times higher than wood pellets at nominal load and reduced load, respectively. Dust emissions were highest with sunflower husk and lowest with RCG pellets, at both operational modes. The best performance was reported with wood pellets, followed by RCG and pectin pellets, however, wood pellets combustion emitted 1.7 and 2.0 times higher dust{sub DINplus} than RCG at nominal and reduced loads, respectively. Not only fuel specific combustion optimization but also operational load specific optimization is essential for efficient use of agro-pellets in this type of boilers. (author)

  6. Lightning arrestor connector lead magnesium niobate qualification pellet test procedures.

    Tuohig, W. (Honeywell FM& T, Kansas City, MO); Mahoney, Patrick A.; Tuttle, Bruce Andrew; Wheeler, Jill Susanne

    2009-02-01

    Enhanced knowledge preservation for DOE DP technical component activities has recently received much attention. As part of this recent knowledge preservation effort, improved documentation of the sample preparation and electrical testing procedures for lead magnesium niobate--lead titanate (PMN/PT) qualification pellets was completed. The qualification pellets are fabricated from the same parent powders used to produce PMN/PT lightning arrestor connector (LAC) granules at HWF&T. In our report, the procedures for fired pellet surface preparation, electrode deposition, electrical testing and data recording are described. The dielectric measurements described in our report are an information only test. Technical reasons for selecting the electrode material, electrode size and geometry are presented. The electrical testing is based on measuring the dielectric constant and dissipation factor of the pellet during cooling from 280 C to 220 C. The most important data are the temperature for which the peak dielectric constant occurs (Curie Point temperature) and the peak dielectric constant magnitude. We determined that the peak dielectric constant for our procedure would be that measured at 1 kHz at the Curie Point. Both the peak dielectric constant and the Curie point parameters provide semi-quantitative information concerning the chemical and microstructural homogeneity of the parent material used for the production of PMN/PT granules for LACs. Finally, we have proposed flag limits for the dielectric data for the pellets. Specifically, if the temperature of the peak dielectric constant falls outside the range of 250 C {+-} 30 C we propose that a flag limit be imposed that will initiate communication between production agency and design agency personnel. If the peak dielectric constant measured falls outside the range 25,000 {+-} 10,000 we also propose that a flag limit be imposed.

  7. Response to Delibes-Mateos et al. : Pellet size matters

    Rueda, Marta; Rebollo, Salvador; Gálvez-Bravo, Lucía

    2009-05-01

    In Rueda et al. [Rueda, M., Rebollo, S., Gálvez-Bravo, L., 2008. Age and season determine European rabbit habitat use in Mediterranean ecosystems. Acta Oecol. 34, 266-273] we used a threshold of 6 mm faecal pellet diameter to differentiate between adult and juvenile European rabbit ( Oryctolagus cuniculus) habitat use. Delibes-Mateos et al. designed a housing experiment with 12 adult rabbits and criticised the choice of 6 mm as a threshold to separate adult and juvenile rabbit pellets, claiming that adults can produce pellets both larger and smaller than 6 mm in similar proportions. In response to their criticism we argue the following. The selection of a 6 mm threshold has a bibliographic basis, it is not a new method developed by Rueda et al. and produces consistent results when applied in the field. Assuming that Delibes-Mateos et al. results are accurate, we should have found a greater number of 6 mm, overall and seasonally, which is not the case. We believe that the use of commercial pelleted food, keeping animals isolated in small cages for over a year, and the use of adult rabbits only, makes the experimental design used by these authors not suitable to refute the usefulness of separating rabbit pellets smaller and larger than 6 mm diameter as indicators of changes in the relative abundance of juvenile and adult rabbits in the field. Finally, we agree with the authors that the use of indirect methods of animal aging would require case-specific validation studies; however, we believe these studies should be correctly designed.

  8. Quality effects caused by torrefaction of pellets made from Scots pine

    Shang, Lei; Nielsen, Niels Peter K.; Dahl, Jonas; Stelte, Wolfgang; Ahrenfeldt, Jesper; Holm, Jens Kai; Thomsen, Tobias; Henriksen, Ulrik B.

    2012-01-01

    for grinding the pellet samples in a bench scale disc mill. Particle size distribution measurements after grinding indicated a significant increase of small particles (diameterca. 2mm). To further analyze the effect on strength, the mechanical durability of pellets was tested according to wood pellet...

  9. Twin-Screw Extruder and Pellet Accelerator Integration Developments for ITER

    Meitner, Steven J [ORNL; Baylor, Larry R [ORNL; Combs, Stephen Kirk [ORNL; Fehling, Dan T [ORNL; Foust, Charles R [ORNL; McGill, James M [ORNL; Rasmussen, David A [ORNL; Maruyama, So [ITER Organization, Cadarache, France

    2011-01-01

    The ITER pellet injection system consisting of a twinscrew frozen hydrogen isotope extruder, coupled to a combination solenoid actuated pellet cutter and pneumatic pellet accelerator, is under development at the Oak Ridge National Laboratory. A prototype extruder has been built to produce a continuous solid deuterium extrusion and will be integrated with a secondary section, where pellets are cut, chambered, and launched with a single-stage pneumatic accelerator into the plasma through a guide tube. This integrated pellet injection system is designed to provide 5 mm fueling pellets, injected at a rate up to 10 Hz, or 3 mm edge localized mode (ELM) triggering pellets, injected at higher rates up to 20 Hz. The pellet cutter, chamber mechanism, and the solenoid operated pneumatic valve for the accelerator are optimized to provide pellet velocities between 200-300 m/s to ensure high pellet survivability while traversing the inner wall fueling guide tubes, and outer wall ELMpacing guide tubes. This paper outlines the current twin-screwextruder design, pellet accelerator design, and the integrationrequired for both fueling and ELM pacing pellets.

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

    Fabrication of ThO pellets for EBR-II irradiation testing and fabrication of UO2 and PuO2-UO2 pellets for United Kingdom Prototype Fast Reactor (PFR) irradiation testing is discussed. Effect of process parameters on density and microstructure of pellets fabricated by the cold press and sinter technique is reviewed

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

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

  12. Adsorption of trace metals to plastic resin pellets in the marine environment

    Plastic production pellets collected from beaches of south west England contain variable concentrations of trace metals (Cr, Co, Ni, Cu, Zn, Cd and Pb) that, in some cases, exceed concentrations reported for local estuarine sediments. The rates and mechanisms by which metals associate with virgin and beached polyethylene pellets were studied by adding a cocktail of 5 μg L−1 of trace metals to 10 g L−1 pellet suspensions in filtered seawater. Kinetic profiles were modelled using a pseudo-first-order equation and yielded response times of less than about 100 h and equilibrium partition coefficients of up to about 225 ml g−1 that were consistently higher for beached pellets than virgin pellets. Adsorption isotherms conformed to both the Langmuir and Freundlich equations and adsorption capacities were greater for beached pellets than for virgin pellets. Results suggest that plastics may represent an important vehicle for the transport of metals in the marine environment. - Highlights: ► Beached plastic production pellets contain considerable concentrations of trace metals. ► In laboratory experiments trace metals are shown to adsorb to both virgin and beached pellets. ► Metal adsorption is greater on aged pellets. ► Pellets may represent an important vehicle for metal transport in the marine environment. - Trace metals accumulate on plastic resin pellets in the marine environment through adsorption to the polymer and to chemical and biological attritions thereon.

  13. The Feasibility of Pellet Re-Fuelling of a Fusion Reactor

    Chang, Tinghong; Jørgensen, L. W.; Nielsen, P.;

    1980-01-01

    The feasibility of re-fuelling a fusion reactor by injecting pellets of frozen hydrogen isotopes is reviewed. First a general look is taken of the dominant energy fluxes received by the pellet, the re-fuelling rate required and the relation between pellet size, injection speed and frequency...

  14. Piezooptic effect of absorbing environment

    Ю. А. Рудяк

    2013-07-01

    Full Text Available Application of piezooptic effect of absorbing environment for the definition of the parameter of stress deformation state was examined. The analysis of dielectric permeability tensor of imaginary parts was done. It is shown that changes in the real part dielectric permeability tensor mainly the indicator of fracture was fixed by means of mechanics interference methods and the changes in the imaginary part (α – real rate of absorption can be measured by means of analysis of light absorption and thus stress deformation state can be determined

  15. Fabrication and characterization of dysprosia and alumina based inert matrix neutron absorbers

    Among the elements of the lanthanides series, dysprosium has interesting nuclear properties. Its high thermal neutron absorption cross-section makes it a good neutron absorber. The best ceramic compound apt for nuclear use is its oxide, the disprosia (Dy2O3). In order to fabricate neutron absorbers diluted in an inert matrix, it is relevant to study the preparation of a ceramic compound based on alumina (Al2O3) and disprosia. In this work, we characterize a particular composition (44,5wt% Dy2O3, 55,5wt% Al2O3) by determining the geometrical density, microstructure and phase formation. The chosen composition corresponds to the lowest temperature eutectic of the alumina-disprosia system, allowing the sintering to proceed at 1700 oC in air. Comparing the data of the green and sinterized pellets, the relative shrinking is of about 17 %, in the same proportion both for diameter and length. The corresponding volumetric reduction is of about 43 %, indicating an increase of the relative geometric density of ∼ 70 %. X-ray diffraction analysis shows the existence of two phases corresponding to the lower eutectic: Dy3Al5O12 and Al2O3. The calculated theoretical density is ∼ 5.2 g/cm3. Consequently, the relative density of the pellets is 92 %, indicating the feasibility for the fabrication of the proposed material. In a near future, samples will be irradiated to evaluate their behavior for nuclear use.

  16. The confirmation method of disposal about the pellet and granular solid wastes and the pellet solid wastes (Revised edition 2)

    The production of pellet solid wastes are scheduled in Fukushima Daiichi and Tokai Daini power plants. The propriety of the disposal confirmation method of these wastes was examined in this issue. Further the outline of the confirmation method of waste disposal was partially improved. (M.H.)

  17. Confirmation method of disposal about the pellet and granular solid wastes and the pellet solid wastes (Revised edition 1)

    The production of pellet solid wastes is scheduled in Fukushima Daiichi and Tokai Daini power plants. The propriety of the disposal confirmation method of these wastes was examined in this issue. Further the outline of the confirmation method of waste disposal was partially improved. (M.H.)

  18. Effect of pelleting process variables on physical properties and sugar yields of ammonia fiber expansion pretreated corn stover

    Amber N. Hoover; Jaya Shankar Tumuluru; Farzaneh Teymouri; Garold L. Gresham; Janette Moore

    2014-07-01

    Pelletization process variables including grind size (4, 6 mm), die speed (40, 50, 60 Hz), and preheating (none, 70 degrees C) were evaluated to understand their effect on pellet quality attributes and sugar yields of ammonia fiber expansion (AFEX) pretreated biomass. The bulk density of the pelletized AFEX corn stover was three to six times greater compared to untreated and AFEX-treated corn stover. Also the durability of the pelletized AFEX corn stover was >97.5% for all pelletization conditions studied except for preheated pellets. Die speed had no effect on enzymatic hydrolysis sugar yields of pellets. Pellets produced with preheating or a larger grind size (6 mm) had similar or lower sugar yields. Pellets generated with 4 mm AFEX-treated corn stover, a 60 Hz die speed, and no preheating resulted in pellets with similar or greater density, durability, and sugar yields compared to other pelletization conditions.

  19. Greenhouse gas emission impacts of use of Norwegian wood pellets: a sensitivity analysis

    The rapid growth in wood pellet consumption in Europe has promoted an increase in imports from other continents. In this study, we analyse: (i) the resource use and greenhouse gas (GHG) emissions over the life cycle of wood pellets produced in Western Europe, (ii) the net GHG emission effects of replacing the fossil fuels lignite, hard coal and paraffin with these pellets, (iii) the most important factors impacting on GHG emissions, and (iv) the costs of replacing these fossil fuels with the pellets compared to changes in the net GHG emissions. Over the life cycle of wood pellets, starting from wood harvesting, total emissions amount to 236 kg CO2eq/tonne pellets (43 kg CO2eq/GJ energy output), but can vary between 113 and 482 kg CO2eq/tonne pellets. Substituting lignite in power plants can reduce GHG emissions by about 298 kg CO2eq/GJ energy output (1620 kg CO2eq/tonne pellets), but only by 58 kg CO2eq/GJ energy output in the “Min. substitution effect” scenario where the emissions in the pellet production chain were high and paraffin replaced. The criteria for carbon neutrality are discussed. Including all CO2 emissions from pellet combustion but not carbon sequestration in forest, GHG emissions from the use of pellets are slightly less than from the replaced lignite. The results of our sensitivity analyses indicate the importance of utilizing bioenergy efficiently. Including all or no CO2 emissions from combustion are both simplifications, and, depending on the conditions, net CO2 emissions from pellets lie somewhere between the two. Simple cost estimates suggest that reducing GHG emissions by replacing lignite and hard coal with pellets costs about 60–70 €/tonne CO2eq. Replacement of paraffin with pellets has however positive net returns due to the higher market prices for paraffin than for pellets.

  20. The Swedish fuel pellets industry: Production, market and standardization

    Hoeglund, Jonas

    2008-03-15

    The production and demand for wood-based fuel pellets has increased considerably both in Sweden and internationally the recent years. Today Sweden is one of the leading nations when it comes to production and use of fuel pellets. Despite the favorable development great challenges wait. The all time high production of saw mill by-products is not enough to satisfy the growing demand for by-products, resulting in increasing raw material prices and competition. Seen in a historic context, the pellet industry has been characterized by fluctuations in supply and demand and uncertainty about how changes in governmental subsidies and the development of competitive substitutes will affect the situation. This study presents a broad overview of the Swedish pellet industry. The study had three purposes; to analyze the business situation for the producers, to examine to what extent product standards and environmental certification instruments were used within the industry, and to make an estimate on future potentials and possibilities for the pellet industry. The study was conducted in the form of a questionnaire survey to the manufacturers of fuel pellets in Sweden and the results are based on answers from 55 % of the producers, accounting for 86 % of the total production capacity. The results indicate a rapidly expanding production capacity and at the same time a strained raw material situation. The production increased with as much as 260 % from 2001 to 2007, and the planned capacity expansion totals 708 000 annual tonnes, or over 40 % of the capacity for 2007. During the same period, the competition for raw materials was getting more intense; one third of the producers experience the raw material situation as the largest threat to the production and the majority of firms have evaluated alternative raw materials in response to the increased competition. Among the alternatives examined are for example roundwood and pulp wood. The majority (47 %) of the production go to small

  1. Design considerations for single-stage and two-stage pneumatic pellet injectors

    Performance of single-stage pneumatic pellet injectors is compared with several models for one-dimensional, compressible fluid flow. Agreement is quite good for models that reflect actual breech chamber geometry and incorporate nonideal effects such as gas friction. Several methods of improving the performance of single-stage pneumatic pellet injectors in the near term are outlined. The design and performance of two-stage pneumatic pellet injectors are discussed, and initial data from the two-stage pneumatic pellet injector test facility at Oak Ridge National Laboratory are presented. Finally, a concept for a repeating two-stage pneumatic pellet injector is described. 27 refs., 8 figs., 3 tabs

  2. Ablation of a Deuterium Pellet in a Fusion Plasma Viewed as a Stopping Power Problem

    Chang, C. T.

    1983-01-01

    sublimation energy of hydrogen isotopes, shortly after the direct impact of the electrons, a dense cloud forms around the pellet. This cloud of ablated material then serves as a stopping medium for the incoming electrons, thus prolongs the pellet life-time. As a result, the deep penetration of the pellet into......At present, the most exploited technology to refuel a future fusion reactor is the high speed injection of macroscopic size pellet of solid hydrogen isotopes. The basic idea is that the ablation of a pellet in a fusion reactor is mainly caused by thermal electrons (~ 10 keV) /1/. Due to the low...

  3. "Proposed High Speed Pellet Injection System ""HIPEL"" for Large Helical Device"

    Sudo, S.; Kanno, M.; Kaneko, H.; Saka, S.; Shirai, T; Baba, T

    1993-01-01

    "From the results of the simulation study including pellet ablation and 1-D transport code, it is found that a high speed pellet injector with pellet velocity of more than 3 km/s is necessary for the penetration of the pellet with diameter of 3 mm into the core region under the expected plasma condition of Large Helical Device (LHD) of heliotron/stellarator type with superconducting coils at NIFS in Japan. Therefore, a two stage pellet injector was constructed and tested successfully in order...

  4. Proposed High Speed Pellet Injection System "HIPEL" for Large Helical Device

    Sudo, S.; Kanno, M.; Kaneko, H.; Saka, S.; Shirai, T; Baba, T

    1993-01-01

    From the results of the simulation study including pellet ablation and 1-D transport code, it is found that a high speed pellet injector with pellet velocity of more than 3 km/s is necessary for the penetration of the pellet with diameter of 3 mm into the core region under the expected plasma condition of Large Helical Device (LHD) of heliotron/stellarator type with superconducting coils at NIFS in Japan. Therefore, a two stage pellet injector was constructed and tested successfully in order ...

  5. The Feasibility of Pellet Re-Fuelling of a Fusion Reactor

    Chang, Tinghong; Jørgensen, L. W.; Nielsen, P.; Lengyel, L. L.

    1980-01-01

    The feasibility of re-fuelling a fusion reactor by injecting pellets of frozen hydrogen isotopes is reviewed. First a general look is taken of the dominant energy fluxes received by the pellet, the re-fuelling rate required and the relation between pellet size, injection speed and frequency....... Current available theories of pellet ablation are then discussed. For a given penetration depth inside the reactor, the necessary pellet injection speed is examined in terms of the ablation theory adopted and the temperature and density profiles of the reactor plasma. The interaction between the injected...

  6. Dysprosium titanate as an absorber material for control rods

    Risovany, V.D. E-mail: fae@niiar.ru; Varlashova, E.E.; Suslov, D.N

    2000-09-02

    Disprosium titanate is an attractive control rod material for the thermal neutron reactors. Its main advantages are: insignificant swelling, no out-gassing under neutron irradiation, rather high neutron efficiency, a high melting point ({approx}1870 deg. C), non-interaction with the cladding at temperatures above 1000 deg. C, simple fabrication and easily reprocessed non-radioactive waste. It can be used in control rods as pellets and powder. The disprosium titanate control rods have worked off in the MIR reactor for 17 years, in VVER-1000 - for 4 years without any operating problems. After post-irradiation examinations this type of control rod having high lifetime was recommended for the VVER and RBMK. The paper presents the examination results of absorber element dummies containing dysprosium titanate, irradiated in the SM reactor to the neutron fluence of 3.4x10{sup 22} cm{sup -2} (E>0.1 MeV) and, also, the data on structure, thermal-physical properties of dysprosium titanate, efficiency of dysprosium titanate control rods.

  7. Dysprosium titanate as an absorber material for control rods

    Risovany, V. D.; Varlashova, E. E.; Suslov, D. N.

    2000-09-01

    Disprosium titanate is an attractive control rod material for the thermal neutron reactors. Its main advantages are: insignificant swelling, no out-gassing under neutron irradiation, rather high neutron efficiency, a high melting point (˜1870°C), non-interaction with the cladding at temperatures above 1000°C, simple fabrication and easily reprocessed non-radioactive waste. It can be used in control rods as pellets and powder. The disprosium titanate control rods have worked off in the MIR reactor for 17 years, in VVER-1000 - for 4 years without any operating problems. After post-irradiation examinations this type of control rod having high lifetime was recommended for the VVER and RBMK. The paper presents the examination results of absorber element dummies containing dysprosium titanate, irradiated in the SM reactor to the neutron fluence of 3.4×10 22 cm -2 ( E>0.1 MeV) and, also, the data on structure, thermal-physical properties of dysprosium titanate, efficiency of dysprosium titanate control rods.

  8. A data mining approach to optimize pellets manufacturing process based on a decision tree algorithm.

    Ronowicz, Joanna; Thommes, Markus; Kleinebudde, Peter; Krysiński, Jerzy

    2015-06-20

    The present study is focused on the thorough analysis of cause-effect relationships between pellet formulation characteristics (pellet composition as well as process parameters) and the selected quality attribute of the final product. The shape using the aspect ratio value expressed the quality of pellets. A data matrix for chemometric analysis consisted of 224 pellet formulations performed by means of eight different active pharmaceutical ingredients and several various excipients, using different extrusion/spheronization process conditions. The data set contained 14 input variables (both formulation and process variables) and one output variable (pellet aspect ratio). A tree regression algorithm consistent with the Quality by Design concept was applied to obtain deeper understanding and knowledge of formulation and process parameters affecting the final pellet sphericity. The clear interpretable set of decision rules were generated. The spehronization speed, spheronization time, number of holes and water content of extrudate have been recognized as the key factors influencing pellet aspect ratio. The most spherical pellets were achieved by using a large number of holes during extrusion, a high spheronizer speed and longer time of spheronization. The described data mining approach enhances knowledge about pelletization process and simultaneously facilitates searching for the optimal process conditions which are necessary to achieve ideal spherical pellets, resulting in good flow characteristics. This data mining approach can be taken into consideration by industrial formulation scientists to support rational decision making in the field of pellets technology. PMID:25835791

  9. Improved fueling and transport barrier formation with pellet injection from different locations on DIII-D

    Pellet injection has been employed on DIII-D from different injection locations to optimize the mass deposition for density profile control and internal transport barrier formation. Transport barriers have been formed deep in the plasma core with central mass deposition from high field side (HFS) injected pellets and in the edge with pellets that trigger L-mode to H-mode transitions. Pellets injected from all locations can trigger the H-mode transition, which depends on the edge density gradient created and not on the radial extent of the pellet deposition. Pellets injected from inside the magnetic axis from the inner wall or vertical port lead to stronger central mass deposition than pellets injected from the low field side (LFS) and thus yield deeper more efficient fueling. (author)

  10. Proposed high speed pellet injection system 'HIPEL' for Large Helical Device

    From the results of the simulation study including pellet ablation and 1-D transport code, it is found that a high speed pellet injector with pellet velocity of more than 3 km/s is necessary for the penetration of the pellet with diameter of 3 mm into the core region under the expected plasma condition of Large Helical Device (LHD) of heliotron/stellarator type with superconducting coils at NIFS in Japan. Therefore, a two stage pellet injector was constructed and tested successfully in order to obtain the pellet velocity range of 3 km/s. Based upon the above results, a high speed flexible multiple-pellet injection system 'HIPEL' for LHD is proposed. HIPEL consists of independent (1) 10 two-stage gun barrels and (2) 10 single-stage gun barrels. It has multi purposes such as refueling and flexible density profile control, diagnostics and the other functions. (author)

  11. Plasma confinement of large-size-pellet DT fuel in inertial confinement fusion

    In this paper we discuss a concept of a large-size-pellet ion-beam inertial confinement fusion (ICF) in which a DT fuel pellet is more than several tens mg. In the large-size-pellet ICF the fuel is compressed to less than 1000 times the solid density, for example about 100 times the solid density in order to realize ρR > 1 - 3g/cm2. Because of the low compression ratio, constraints required for the uniform fuel implosion are relaxed compared with those for a high-compression implosion of a small pellet. This concept of the large-size-pellet implosion may present another approach to ICF. In this paper we present a simple estimation for the concept and one-dimensional numerical analyses for the large-size-pellet implosion. A simple linear estimation for the Rayleigh-Taylor instability presents that the fuel pellet may not be destroyed by the instability. (author)

  12. Ammonia-pellet generation system for the Baseball II-T target plasma experiment

    The irradiation of a small pellet by a pulsed laser is one method of producing a startup target plasma for plasma experiments employing neutral-beam injection. A system for generating charged, uniformly sized, solid-ammonia, 150-μm-diam, spherical pellets having a charge-to-mass ratio of 10-4 C/kg is described. These pellets are electrostatically guided at a speed of 32 m/sec (over a distance of several meters) to a laser focal zone. This complete system (pellet generation and pellet guidance) has been successfully operated on a 3-m test stand where 250-μm-diam pellets were regularly irradiated by a pulsed, 30-J CO2 laser. The system is now installed on the Baseball II-T experiment; in preliminary tests, several 150-μm-diam pellets were irradiated with the pulsed 300-J CO2 laser

  13. Dry bag isostatic pressing for improved green strength of surrogate nuclear fuel pellets

    Dry bag isostatic pressing is proposed for mass production of nuclear fuel pellets. Dry bag isostatically pressed rods of a fuel surrogate (95% CeO2-5% HfO2) 200 mm long by 8 mm diameter were cut into pellets using a wire saw. Four different binders and CeO2 powder obtained from two different sources were investigated. The strength of the isostatically pressed pellets for all binder systems measured by diametral compression was about 50% higher than pellets produced by uniaxial dry pressing at the same pressure. It was proposed that the less uniform density of uniaxially pressed pellets accounted for the lower strength. The strength of pellets containing CeO2 powder with significantly higher moisture content was five times higher than pellets containing CeO2 powder with a low moisture content even though they were 25% less dense. Capillary pressure of the moisture was thought to supply the added binding strength.

  14. Wood pellet heating plants. Market survey. 4. upd. ed.; Hackschnitzel-Heizung. Marktuebersicht

    NONE

    2012-11-15

    Wood pellets from the agriculture and forestry offer an enormous potential for the development of the use of bio energy in the private area as well as in industry and commerce. Within the market survey 'Wood pellet heating systems', the Fachagentur Nachwachsende Rohstoffe e.V. (Guelzow-Pruezen, Federal Republic of Germany) reported on the targets and measures of the Federal Government with respect to the heating with biomass, wood pellets as solid biofuels (standardization of solid biofuels, supply, features, evaluation), wood pellet heating plants, economic considerations, market survey on wood pellet heating plants as well as list of addresses for producers of wood pellet heating plants and suppliers of wood pellets.

  15. The CIT [compact ignition tokamak] pellet injection system: Description and supporting research and development

    The Compact Ignition Tokamak (CIT) will use an advance, high-velocity pellet injection system to achieve and maintain ignited plasmas. Two pellet injectors are provided: a moderate-velocity (1-to 1.5-km/s), single-stage pneumatic injector with high reliability and a high-velocity (4- to 5-km/s), two-stage pellet injector that uses frozen hydrogenic pellets encased in sabots. Both pellet injectors are qualified for operation with tritium feed gas. Issues such as performance, neutron activation of injector components, maintenance, design of the pellet injection vacuum line, gas loads to the reprocessing system, and equipment layout are discussed. Results and plans for supporting research and development (R and D) in the areas of tritium pellet fabrication and high-velocity, repetitive two-stage pneumatic injectors are presented. 7 refs., 4 figs., 2 tabs

  16. KINIK, Absorber Rod Calibration Kinetics

    1 - Description of program or function: KINIK is an inverse kinetic code that solves the inverse form of the point kinetic equations using the Runge-Kutta method. An optimization procedure is involved to control the time step and to reduce the running time. Up to 24 delayed neutron groups of different types (in case of heavy water as moderator or beryllium as reflector) are considered. KINIK is commonly applied to determine reactivity worths and to calibrate absorber rods. Following a rod drop, neutron flux or power is recorded as a function of time and used as input. 2 - Method of solution: The inverse point kinetic equations are numerically solved for each time step using the Runge-Kutta method. The input data resulting from measurements are first approximated by polynomials of maximum degree 10 using a least-squares approach

  17. Preparation of Fluidization Feed of UO2 Pellets by Oxidation

    The investigation of oxidation of uranium dioxide (UO2) pellets to thetri uranium octoxide (U3O8) powder had been carried. Several factor suchtemperature, time of oxidation and the concentration of air are important.The oxidation of UO2 pellet are carried out on electric furnace atatmosphere as media. The oxidation temperature started at 300 oC, 400 oC,500 oC, and 600 oC along 1 hour. The time oxidation removed to 2 hours and3 hours. The efficiency of oxidation are the ratio of the weight of thepowder product are the uranium content, true density, and specific surfacearea. Result the optimum temperature are 500 oC along 3 hours, uraniumcontent : 84.78%, true density: 8.8293 g/cm3 and specific surface area :0.389071 m2/g. (author)

  18. The heat exchanger of small pellet boiler for phytomass

    Mičieta, Jozef; Lenhard, Richard; Jandačka, Jozef

    2014-08-01

    Combustion of pellets from plant biomass (phytomass) causes various troubles. Main problem is slagging ash because of low melting temperature of ash from phytomass. This problem is possible to solve either improving energetic properties of phytomass by additives or modification of boiler construction. A small-scale boiler for phytomass is different in construction of heat exchanger and furnace mainly. We solve major problem - slagging ash, by decreasing combustion temperature via redesign of pellet burner and boiler body. Consequence of lower combustion temperature is also lower temperature gradient of combustion gas. It means that is necessary to design larger heat exchanging surface. We plane to use underfed burner, so we would utilize circle symmetry heat exchanger. Paper deals design of heat exchanger construction with help of CFD simulation. Our purpose is to keep uniform water flux and combustion gas flux in heat exchanger without zone of local overheating and excess cooling.

  19. Simulation analysis of JT-60 pellet injection experiments

    The transport of pellet fuelled plasmas in JT-60 has been investigated with a predictive tokamak transport code. The inward pinch of ∼0.2 m/sec at the half plasma radius and the reduced particle diffusion coefficient in the central region of 0.1 m2/s are necessary to explain the peaked density profile observed in the pellet fuelled plasma. These particle transport properties yield the improved energy confinement in the plasma with the strong particle source in the hot core region under the sawtooth suppression condition. The plasma current dependence of the improved stored energy can be explained by the assumption that the particle confinement is good within the q = 1 surface. (author)

  20. Fabrication characteristics of DUPIC fuel pellets at DFDF

    In this study, based on the simulated DUPIC fuel fabrication experiment and DUPIC fuel characterization experiment at PIEF, DUPIC fuel manufacturing technologies and processes have been developed at DFDF(DUPIC Fuel Development Facility, IMEF M6). Using DUPIC powder prepared by the oxidation and reduction processes, the DUPIC fuel pellets were fabricated and characterized in terms of the process parameters such as the burn-up of spent fuel, compaction pressure, sintering temperature, and sintering time. As a result of the experiment, DUPIC pellets were characterized by 10.02 ∼ 10.43 g/cm3 of sintered density, 7.26 ∼ 9.48μm of grain size, and less than Ra 0.8μm of surface roughness at hot cell. The optimum DUPIC processes have been established based on the results of the experiment

  1. A device for stacking cylindrical pellets into a column

    The machine according to the invention is characterized by two parallel shafts, slightly spaced apart for forming a track, said shafts being drived by a system of gears and forming an angle of e.g. 10 degrees with respect to the horizontal, in order that the pellets move downwardly along said track while rolling about themselves so as to form a column which is stopped by a movable stop-means, the latter being removed, whenever said columns has reached the desired height, so as to allow said column to be pushed into a receiver tube. Such a machine is suitable in particular for introducing pellets into the sheath of a fuel rod or element in a nuclear reactor

  2. Aiming for market leadership - from electricity utility to pellets manufacturer

    This short article describes the plans of a small Swiss electricity utility to break out of its traditional role in power generation and the distribution of electricity and go into the production of wood pellets. The pellets, which are to be made from waste wood available from a wood processing facility in the utility's own region, are to be produced on a scale which can be described as being quite large for Switzerland. The article discusses this unusual approach for a Swiss power utility, which also operates a wood-fired power station and has diversified into other areas such as electrical house installations and overland power lines. The markets being aimed for are described, including modern low-energy-consumption housing projects

  3. Pellet bed reactor for multi-modal space power

    A review of forthcoming space power needs for both civil and military missions indicates that power requirements will be in tens of megawatts. It is envisioned that the electrical power requirements will be two-fold; long-duration low power will be needed for station keeping, communications and/or surveillance, while short-duration high power will be required for pulsed power devices. These power characteristics led to authors to propose a multi-modal space power reactor using a pellet bed design. Characteristics desired for such a multi-megawatt reactor power source are the following: standby, alert and pulsed power modes; high thermal output heat source (around 1000 MWt peak power); long lifetime standby power (10-30 yrs); high temperature output (1500-1750 K); rapid burst power transition; high reliability (>95%); and meets stringent safety requirements. The proposed pellet bed reactor concept is designed to satisfy these characteristics

  4. Analysis of Pelletizing of Granulometric Separation Powder from Cork Industries

    Irene Montero

    2014-09-01

    Full Text Available Cork industries generate a considerable amount of solid waste during their processing. Its management implies a problem for companies that should reconsider its reuse for other purposes. In this work, an analysis of pelletizing of granulometric separation powder, which is one of the major wastes in cork industries and which presents suitable properties (as an raw material for its thermal use, is studied. However, its characteristic heterogeneity, along with its low bulk density (which makes its storage and transportation difficult are restrictive factors for its energy use. Therefore, its densified form is a real alternative in order to make the product uniform and guarantee its proper use in boiler systems. Thus, the cork pellets (from granulometric separation powder in the study met, except for ash content specification, the specifications in standard European Norm EN-Plus (B for its application as fuel for domestic use.

  5. preparation of powders and pellets for UO2 fuel production

    Most of the commercial nuclear power plants use uranium dioxide (UO2) as fuel due to physical and chemical properties of UO2. UO2 is a ceramic material it has low thermal conductivity and high melting point and therefore can be used in nuclear power plants. The nuclear grade uranium compounds are produced at Nuclear Fuel Technology Department of CNRTC using the following route: desolution and purification of yellow cake and precipitation of ammonium diuranate (ADU), calcination of ADU in air and reduction in hydrogen atmosphere to UO2. The UO2 powder characterized by specific surface area,particle size and O/U determinations. 0.2 % stearic acid is added to the UO2 powder and green pellets of 15 mm diameter are pressed. Hydraulic press with a floating die system and double pressing action is used. The gree pellets are then sintered

  6. Density gradients in ceramic pellets measured by computed tomography

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

  7. Pellets de trigo e soja produzidos por extrusão Wheat and soybean pellets produced by extrusion-cooking

    Sin Huei Wang

    2008-09-01

    Full Text Available A mistura de trigo e soja representa uma importante fonte calórico-protéica com proteínas de boa qualidade. Apesar disso, a utilização da soja como ingrediente tem sido limitada pelo seu sabor de feijão cru (beany flavor, o qual é melhorado pelo processo de extrusão. Foram estudados os efeitos de umidade da mistura, Temperatura de Barril (TB e Velocidade de Rotação de Parafuso (VRP, Nº 5 do extrusor no Índice de Expansão (IE, no Índice de Solubilidade em Água (ISA e nas características sensoriais de pellets produzidos com mistura de trigo e soja (90:10, objetivando a otimização deste processo para a obtenção de pellets fritos com melhores qualidades sensoriais. A farinha mista crua foi extrusada em 2 umidades (32 e 35%, 4 TB (60 a 90 °C e 4 VRP (60 a 150 rpm, totalizando 32 tratamentos. O pellet frito, preparado com a farinha mista com 32% de umidade e extrusada em 60 rpm a 80 °C, apresentou o maior IE e as melhores qualidades sensoriais (aparência, sabor e textura, sendo preferido pela equipe de provadores não treinados, tanto com sabor de bacon como com sabor de queijo.The mixture of wheat with soybean represents an important calorie-protein source with good protein quality. In spite of this, the use of soybeans as an ingredient has been limited by their beany flavor, which is improved by the extrusion process. Effects of mixture moisture, Barrel Temperature (BT and Screw-Speed (SS, Nº 5 on Expansion Index (EI, Water Solubility Index (WSI and sensory characteristics of pellets produced with a wheat-soybean (90:10 mixture were studied, in order to optimize this process for obtaining fried pellets with better sensory qualities. Raw mixed flour was extruded at two moisture contents (32 and 35%, four BT (60 to 90 °C and four SS (60 to 150 rpm, totalizing 32 treatments. The fried pellets, prepared with the mixed flour with 32% moisture and extruded at 60 rpm and 80 °C, presented the greatest EI and the best sensory

  8. Manufacturing of nuclear fuel pellets by using re-oxidized U3O8 powder

    In a commercial UO2 fuel pellets manufacturing process, defective UO2 pellets which do not meet the fuel specifications of density and diameter may be produced. Defective UO2 pellets should be reused in manufacturing new UO2 pellets. It is a common recycling method that defective UO2 pellets are oxidized in air at about 450 .deg. C to make U3O8 powder and then added to UO2 powder. Because the recycled U3O8 powder has very low sintering activity compared to the UO2 powder, it tends to decrease the density of UO2 pellets. Other pellet properties such as grain size and open porosity are a little degraded by the addition of the U3O8 powder. So the amount of the recycled U3O8 powder is generally not higher than 10 wt% in UO2 powder. There has been a series of work to deal with the heat treatments of the recycled U3O8 powder in order to improve its sintering activity. This paper deals with the recycling process of defective UO2 pellets or scraps. The defective UO2 pellets are oxidized to U3O8 powders at conventional temperature of 350 .deg. C and 450 .deg. C in air. Those powders are pressed into green pellets and then sintered at 1700 .deg. C in H2 flowing gas. Sintered pellets are reoxidized to U3O8 at 450 .deg. C in air. Re-oxidized powders are added to virgin UO2 powders to fabricate UO2 pellets. This paper shows that the re-oxidized U3O8 powder sizes and the BET surface areas are greatly dependent on the sintered density of UO2 pellets before oxidation. The re-oxidized U3O8 powders having a large BET surface area significantly promote a grain growth of UO2 pellets

  9. EMISSIONS CHARACTERISTICS OF A RESIDENTIAL PELLET BOILER AND A STOVE

    Win, Kaung Myat; Persson, Tomas

    2010-01-01

    Gaseous and particulate emissions from a residential pellet boiler and a stove are measured at a realistic 6-day operation sequence and during steady state operation. The aim is to characterize the emissions during each phase in order to identify when the major part of the emissions occur to enable actions for emission reduction where the savings can be highest. The characterized emissions comprised carbon monoxide (CO), nitrogen oxide (NO), total organic carbon (TOC) and particulate matter (...

  10. Design and Evaluation of Self-Nanoemulsifying Pellets of Repaglinide

    Desai, N S; Nagarsenker, M. S.

    2013-01-01

    The aim of study was to develop self-nanoemulsifying pellets (SNEP) for oral delivery of poorly water soluble drug, repaglinide (RPG). Solubility of RPG in oily phases and surfactants was determined to identify components of self-nanoemulsifying drug delivery system (SNEDDS). The surfactants and cosurfactants were screened for their ability to emulsify oily phase. Ternary phase diagrams were constructed to identify nanoemulsification area for the selected systems. SNEDDS formulations with glo...

  11. Heating system of pellet samples integrated with terahertz spectrometer

    Sterczewski, L. A., E-mail: lukasz.sterczewski@pwr.edu.pl; Grzelczak, M. P.; Plinski, E. F. [Department of Electronics, Wroclaw University of Technology, 27 Wybrzeze Wyspianskiego St., 50-370 Wroclaw (Poland)

    2016-01-15

    This article describes automation of temperature-dependent terahertz spectroscopic experiments. The proposed dual-heater temperature controller based on a cascade proportional-integral-derivative algorithm provides smooth temperature changes in the polyethylene-based pharmaceutical pellet samples. The device has been integrated with a terahertz time-domain spectrometer. Thermodynamic experiments can now be performed without any probe inserted into the measured sample. Selected results of temperature-induced evolution in terahertz spectra are presented.

  12. Zooplankton fecal pellets link fossil fuel and phosphate deposits

    Porter, K.G.; Robbins, E.I.

    1981-01-01

    Fossil zooplankton fecal pellets found in thinly bedded marine and lacustrine black shales associated with phosphate, oil, and coal deposits, link the deposition of organic matter and biologically associated minerals with planktonic ecosystems. The black shales were probably formed in the anoxic basins of coastal marine waters, inland seas, and rift valley lakes where high productivity was supported by runoff, upwelling, and outwelling. Copyright ?? 1981 AAAS.

  13. Assessment of mechanical properties of pellets produced from biomass

    Závada, J.; Nadkanská, H.; Bouchal, T.; Šašek, Petr; Smatanová, N.

    Volume 1, Book 4. Sofie: International Multidisciplinary Scientific GeoConference & EXPO SGEM, 2014, s. 33-40. ISBN 978-619-7105-15-5. ISSN 1314-2704. [International Multidisciplinary Scientific GeoConference. Albena (BG), 20140619] R&D Projects: GA MŠk(CZ) LO1219 Keywords : pellets * biomass * biofuel * strength Subject RIV: DM - Solid Waste and Recycling http://www.sgem.org/sgemlib/spip.php?article4625&lang=en

  14. Analysis of Pelletizing of Granulometric Separation Powder from Cork Industries

    Irene Montero; Teresa Miranda; Francisco José Sepúlveda; José Ignacio Arranz; Sergio Nogales

    2014-01-01

    Cork industries generate a considerable amount of solid waste during their processing. Its management implies a problem for companies that should reconsider its reuse for other purposes. In this work, an analysis of pelletizing of granulometric separation powder, which is one of the major wastes in cork industries and which presents suitable properties (as an raw material) for its thermal use, is studied. However, its characteristic heterogeneity, along with its low bulk density (which makes ...

  15. FORMULATION AND EVALUATION OF METAPROLOL SUCCINATE EXTENDED RELEASE PELLETS

    Ahishek Perumalla; Manivannan, R.; Nelluri Rama Rao; M. Radhakrishna; Devareddy Sandeep

    2012-01-01

    The aim and of the present study is to develop a pharmaceutically stable and quality improved formulation of Metoprolol succinate extended release pellets. To achieve this goal various prototype formulation trials were formulated and the evaluated with respect to the various quality controls such as dissolution, assay and stability studies will be under taken. Metoprolol succinate is used in the treatment of hyper tension, angina pectoris (chest pain) and myocardial infarction. The study was...

  16. Quality of Pelleted Olive Cake for Energy Generation

    Tea Brlek; Neven Voća; Tajana Krička; Đuro Vukmirović; Radmilo Čolović

    2012-01-01

    Olive cake is by-product of olive oil production. This material cannot be stored in original condition for a long time because it has high water content and relatively high portion of oil that causes rapid deterioration. Thus it is necessary to investigate possible methods of remediation of such by-product, where utilization for energy generation presents a useful option. Several studies have been conducted on energy generation from olive cake, however not one that includes pelleting as a pre...

  17. Emissions from realistic operation of residential wood pellets heating systems

    Win, Kaung Myat

    2015-01-01

    Emissions from residential combustion appliances vary significantly depending on the firing behaviours and combustion conditions, in addition to combustion technologies and fuel quality. Although wood pellet combustion in residential heating boilers is efficient, the combustion conditions during start-up and stop phases are not optimal and produce significantly high emissions such as carbon monoxide and hydrocarbon from incomplete combustion. The emissions from the start-up and stop phases of...

  18. Thermal Diffusivity of Carbon Pellets (CPs) Treated with KOH

    M. Haydari; M. M. Moksin; A. E. Abdelrahman; M. Deraman; W. M.M. Deraman; W. M.M. Yunus; I. V Grozescu

    2008-01-01

    In this work thermal diffusivity of carbon pellets (CPs) treated with different percentage level of KOH has been studied. Thermal diffusivity measurements were carried out at room temperature by using photoflash technique. The technique consists of a camera flash having approximately 5 ms pulse duration for heating and a thin film of polyvinylidene difluoride (PVDF) attached to the back of the samples for signal detection. Eight carbon samples treated with different percentage level of KOH (0...

  19. The interaction between clothing and air weapon pellets.

    Wightman, G; Wark, K; Thomson, J

    2015-01-01

    Comparatively few studies have been carried out on air weapon injuries yet there are significant number of injuries and fatalities caused by these low power weapons because of their availability and the public perception that because they need no licence they are assumed to be safe. In this study ballistic gel was tested by Bloom and rupture tests to check on consistency of production. Two series of tests were carried out firing into unclothed gel blocks and blocks loosely covered by different items of clothing to simulate attire (tee shirt, jeans, fleece, and jacket). The damage to the clothing caused by different shaped pellets when fired at different ranges was examined. The apparent hole size was affected by the shape of pellet (round, pointed, flat and hollow point) and whether damage was predominantly caused by pushing yarn to one side or by laceration of the yarn through cutting or tearing. The study also compared penetration into clothed gel and unclothed gel under identical conditions, and loose clothing greatly reduced penetration. With loose clothing at 9.1 m range clothing reduced penetration to 50-70% of the penetration of unclothed gel but at 18.3m range only 7 out of 36 shots penetrated the gel. This cannot be accounted for by the energy loss at the longer range (3-7% reduction from 9.1 m to 18.3 m range in unclothed gels) and it is suggested that impulse may have a role to play. Shots that did not penetrate the gel were used to estimate the possible stopping time for the pellet (around 75 μs) and force (1700 N) or stress (100 MPa) required to bring the pellet to a halt. Even with these low energy projectiles, cloth fibres were entrained in the gel showing the potential for penetration of the body and subsequent infection. PMID:25460102

  20. The quality analyses of olive cake fuel pellets - mathematical approach

    Brlek Tea I.

    2016-01-01

    Full Text Available This article investigates the effect of processing parameters (conditioning temperature and binder content, on final quality of produced agro-pellets for heat energy generation, obtained from four different olive cultivars using different technological parameters. Technological, physical and chemical properties of pellets (carbon, hydrogen, nitrogen and sulphur content, particle density, abrasion length, moisture, ash content, higher and lower heating values, fixed carbon and volatile matter content have been determined to assess their quality. The performance of Artificial Neural Network (ANN was compared with the performance of second order polynomial (SOP model, as well as with the obtained experimental data in order to develop rapid and accurate mathematical model for prediction of final quality parameters of agro-pellets. SOP model showed high coefficients of determination (r2, between 0.692 and 0.955, while ANN model showed high prediction accuracy with r2 between 0.544 and 0.994. [Projekat Ministarstva nauke Republike Srbije, br. III 46005 i br. TR-31055

  1. Development of a shielded pellet thermal conductivity measurement apparatus

    At the Hot Engineering Division, development of new PIE techniques for the study on high burnup fuel behavior have been continued. The thermal conductivity in high burnup fuel pellet is one of the most important thermophysical properties. The shielded pellet thermal conductivity apparatus using the laser flash method was developed and it became possible to calculate the thermal conductivity of high burnup fuel pellets. This report describes the results of measurement of the thermal diffusivity of the metallic tantalum and ceramic samples such as alumina, zirconia and mullite, at room temperature to 1800degC. The measured value of the thermal diffusivity with tantalum were correspond to the data of the TPRC data series published by the Purdue University in USA. The thermal diffusivity of the fan shaped tantalum samples was also measured to examine the effect of sample shape. The result of data analysis by the logarithmic method showed small difference between round and fan shaped samples. The measured value of ceramic samples were similar scatter in tantalum one. (author)

  2. Optimisation of efficiency and emissions in pellet burners

    There is a trade-off between the emissions of nitrogen oxides (NOx) and of unburnt hydrocarbons and carbon monoxide (OGC and CO). Decreasing the excess air results in lower NOx emission but also increased emission of unburnt. The efficiency increases, as the excess air is decreased until the losses due to incomplete combustion become too high. The often-high NOx emission in today's pellet burners can be significantly reduced using well-known techniques such as air staging. The development of different chemical sensors is very intensive and recently sensors for CO and OGC have been introduced on the market. These sensors may, together with a Lambda sensor, provide efficient control for optimal performance with respect to emissions and efficiency. In this paper, results from an experimental parameter study in a modified commercial burner, followed by Chemkin simulations with relevant input data and experiments in a laboratory reactor and in a prototype burner, are summarised. Critical parameters for minimisation of NOx emission from pellet burners are investigated in some detail. Also, results from tests of a new sensor for unburnt are reported. In conclusion, relatively simple design modifications can significantly decrease NOx emission from today's pellet burners

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

    American Society for Testing and Materials. Philadelphia

    2008-01-01

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

  4. Design and evaluation of self-nanoemulsifying pellets of repaglinide.

    Desai, N S; Nagarsenker, M S

    2013-09-01

    The aim of study was to develop self-nanoemulsifying pellets (SNEP) for oral delivery of poorly water soluble drug, repaglinide (RPG). Solubility of RPG in oily phases and surfactants was determined to identify components of self-nanoemulsifying drug delivery system (SNEDDS). The surfactants and cosurfactants were screened for their ability to emulsify oily phase. Ternary phase diagrams were constructed to identify nanoemulsification area for the selected systems. SNEDDS formulations with globule size less than 100 nm were evaluated for in vivo anti-hyperglycemic activity in neonatal streptozotocin rat model. A significant reduction in glucose levels was produced by optimized SNEDDS formulation in comparison to the control group. The optimized SNEDDS formulations were pelletized via extrusion/spheronization technique using microcrystalline cellulose and lactose. SNEP were characterized by X-ray powder diffraction and scanning electron microscopy. X-ray diffraction study indicated loss of crystallinity of RPG in SNEP. The SNEP exhibited good flow properties, mechanical strength and formed nanoemulsion with globule size less than 200 nm. SNEP showed in vitro release of more than 80% RPG in 10 min which was significantly higher than RPG containing reference pellets. In conclusion, our studies illustrated that RPG, a poorly water soluble drug can be successfully formulated into SNEP which can serve as a promising system for the delivery of poorly water soluble drugs. PMID:23775389

  5. Cost and other effects of reduced fuel pellet diameters

    With the everchanging economic and licensing environment of the nuclear fuel cycle, Combustion Engineering (C-E) considered reducing the fuel pellet diameter of its current fuel rod designs. However, the economic incentive to reduce the diameter, considering the uncertainty of the assumptions used for the economics analysis, is at best very small. This together with the negative aspects of reduced safety margins, the increased number of discharge fuel assemblies that have to be stored or disposed of each year, and the change from a design of proven reliability all yield the conclusion that the current fuel pellet diameters used by C-E should not be changed. The conclusion differs from that reported by others as a result of the use of more sophisticated neutronics calculations and more realistic definition of fuel cycle cost parameters. This analysis was performed using C-E's most advanced neutronics model, DIT. The model was applied to high burnup fuel (48 MWd/kgU) and cores operating on 18-month cycles. To maintain constant batch average discharge burnup and constant energy production, the number of assemblies in each reload batch was increased as the fuel pellet radius decreased. Finally, the fabrication and disposal price was adjusted as the assembly loading decreased such that the cost to fabricate or dispose of each assembly was kept constant

  6. Optimization of extrusion process for production of nutritious pellets

    Ernesto Aguilar-Palazuelos

    2012-03-01

    Full Text Available A blend of 50% Potato Starch (PS, 35% Quality Protein Maize (QPM, and 15% Soybean Meal (SM were used in the preparation of expanded pellets utilizing a laboratory extruder with a 1.5 × 20.0 × 100.0 mm die-nozzle. The independent variables analyzed were Barrel Temperature (BT (75-140 °C and Feed Moisture (FM (16-30%. The effect of extrusion variables was investigated in terms of Expansion Index (EI, apparent density (ApD, Penetration Force (PF and Specific Mechanical Energy (SME, viscosity profiles, DSC, crystallinity by X-ray diffraction, and Scanning Electronic Microscopy (SEM. The PF decreased from 30 to 4 kgf with the increase of both independent variables (BT and FM. SME was affected only by FM, and decreased with the increase in this variable. The optimal region showed that the maximum EI was found for BT in the range of 123-140 °C and 27-31% for FM, respectively. The extruded pellets obtained from the optimal processing region were probably not completely degraded, as shown in the structural characterization. Acceptable expanded pellets could be produced using a blend of PS, QPM, and SM by extrusion cooking.

  7. The infrabuccal pellet piles of fungus-growing ants.

    Little, Ainslie E F; Murakami, Takahiro; Mueller, Ulrich G; Currie, Cameron R

    2003-12-01

    Fungus-growing ants (Attini) live in an obligate mutualism with the fungi they cultivate for food. Because of the obligate nature of this relationship, the success of the ants is directly dependent on their ability to grow healthy fungus gardens. Attine ants have evolved complex disease management strategies to reduce their garden's exposure to potential parasitic microbes, to prevent the establishment of infection in their gardens, and to remove infected garden sections. The infrabuccal pocket, a filtering device located in the oral cavity of all ants, is an integral part of the mechanisms that leaf-cutter ants use to prevent the invasion and spread of general microbial parasites and the specific fungal-garden parasite Escovopsis. Fungus-growing ants carefully groom their garden, collecting general debris and pathogenic spores of Escovopsis in their infrabuccal pocket, the contents of which are later expelled in dump chambers inside the nest or externally. In this study we examined how a phylogenetically diverse collection of attine ants treat their infrabuccal pellets. Unlike leaf-cutters that deposit their infrabuccal pellets directly in refuse piles, ants of the more basal attine lineages stack their infrabuccal pellets in piles located close to their gardens, and a separate caste of workers is devoted to the construction, management, and eventual disposal of these piles. PMID:14676952

  8. High Burnup UO2 Fuel Pellets with Dopants for WWER

    The currently achieved level of design and technology developments provided for the implementation of the fuel cycle (4x1) in WWER at the maximal design burnup of 56 MW.day/kgU per FA. Presently in Russia the program is under way to improve the technical and economic parameters of WWER fuel cycles characterized by an increased fuel usability. To meet the requirements placed on the new fuel that ensures the reliable operation under conditions of higher burnups complex activities are under way to optimize the composition and microstructure of fuel pellets as applied to WWER. This paper describes a general approach to providing the stimulated composition and microstructure of fuel via introducing various dopants. Aside from this, the paper presents the experimentally results of studies into the main technologic and operational characteristics of dopant containing fuel pellets including higher grain sizes, pores distribution and oxygen to metal ratio. The results of the experiments made it possible to work out the pilot commercial process of the modified fuel fabrication, to manufacture pellet batches to be semi-commercially operated at NPP with WWER. (author)

  9. Planar Metamaterial Absorber Based on Lumped Elements

    GU Chao; QU Shao-Bo; PEI Zhi-Bin; ZHOU Hang; XU Zhuo; BAI Peng; PENG Wei-Dong; LIN Bao-Qin

    2010-01-01

    @@ We present the design of a planar metamaterial absorber based on lumped elements,which shows a wide-band polarization-insensitive and wide-angle strong absorption.This absorber consists of metal electric resonators,the dielectric substrate,the metal film and lumped elements.The simulated absorbances under two different loss conditions indicate that high absorbance in the absorption band is mainly due to lumped resistances.The simulated absorbances under three different load conditions indicate that the local resonance circuit(lumped resistance and capacitance)could boost up the resonance of the whole RLC circuit.The simulated voltage in lumped elements indicates that the transformation efficiency from electromagnetic energy to electric energy in the absorption band is high,and electric energy is subsequently consumed by lumped resistances.This absorber may have potential applications in many military fields.

  10. Scaling of the Density Peak with Pellet Injection in ITER*%Scaling of the Density Peak with Pellet Injection in ITER*

    P. KLAYWITTAPHAT; T. ONJUN

    2012-01-01

    Scalings of the density peak and pellet penetration length in ITER are developed based on simulations using 1.5D BALDUR integrated predictive modeling code. In these simulations , the pellet ablation is described by the Neutral Gas Shielding (NGS) model with grad-B drift effect taken into account. The NGS pellet model is coupled with a plasma core transport model, which is a combination of an MMM95 anomalous transport model and an NCLASS neoclassical transport model. The BALDUR code with a combination of MMM95 and NCLASS models, together with the NGS model, is used to simulate the time evolution of plasma current, ion and electron temperatures, and density profiles for ITER standard type I ELMy H-mode discharges during the pellet injection. As a result, the scaling of the density peak and pellet penetration length at peak density can be established using this set of predictive simulations that covers a wide range of ITER plasma conditions and pellet parameters. The multiple regression technique is utilized in the development of the scalings. It is found that the scaling for density at center is sensitive to both the plasma and pellet parameters; whereas the scalings for density and location of the additional peak are sensitive to the pellet parameters only.

  11. Multiband Negative Permittivity Metamaterials and Absorbers

    Yiran Tian

    2013-01-01

    Full Text Available Design and characteristics of multiband negative permittivity metamaterial and its absorber configuration are presented in this paper. The proposed multiband metamaterial is composed of a novel multibranch resonator which can possess four electric resonance frequencies. It is shown that, by controlling the length of the main branches of such resonator, the resonant frequencies and corresponding absorbing bands of metamaterial absorber can be shifted in a large frequency band.

  12. A Six-Fold Symmetric Metamaterial Absorber

    Humberto Fernández Álvarez

    2015-04-01

    Full Text Available A novel microwave metamaterial absorber design is introduced along with its manufacturing and characterization. Significant results considering both bandwidth and angular stability are achieved. Parametric analysis and simplified equivalent circuit are provided to give an insight on the key elements influencing the absorber performance. In addition, the constitutive parameters of the effective medium model are obtained and related to the absorber resonant behavior. Moreover, a new thinner and more flexible absorber version, preserving broad bandwidth and angular insensitive performance, is simulated, and an 8 × 8 unit-cells prototype is manufactured and measured for a limited angular margin in an anechoic chamber.

  13. Absorber rod for pebble-bed reactor

    The absorber rod that can be moved into the pebble bed from the top reflector is enclosed by a cladding tube which, if it is completely moved down, ends above the pebble bed and is open at the bottom. Through the cladding tube the absorber rod is cooled with gas. The cladding tube consists of e.g. boron steel. If the absorber rod is drawn it takes along the cladding tube which is moved into the guide tube like a telescope. The rigidity of that part of the absorber rod projecting from the pebble bed is thus guaranteed. (DG)

  14. Metamaterial absorber with random dendritic cells

    Zhu, Weiren; Zhao, Xiaopeng

    2010-05-01

    The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

  15. Plasmonic titanium nitride nanostructures for perfect absorbers

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel; Naik, Gururaj V.; Boltasseva, Alexandra; Guan, Jianguo; Kildishev, Alexander V.; Shalaev, Vladimir M.

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material.Renewable E......We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  16. Results from recent hydrogen pellet acceleration studies with a 2-m railgun

    Kim, K.; Zhang, D.J.; King, T.; Haywood, R.; Manns, W.; Venneri, F.

    1989-12-01

    A new 3.2-mm-diameter, two-stage, fuseless, plasma-arc-driven electromagnetic railgun has been designed, constructed, and successfully operated to achieve a record velocity of 2.67 km/s({sup b}) for 3.2 mmD {times} 4 mmL solid hydrogen pellet. The first stage of this hydrogen pellet injector is a combination of a hydrogen pellet generator and a gas fun. The second stage is a 2-m-long railgun which serves as a booster accelerator. The gas fun accelerates a frozen hydrogen pellet to a medium velocity and injects it into the railgun through a perforated coupling piece, which also serves a pressure-relieving mechanism. An electrical breakdown of the propellant gas, which has followed the pellet from the gas fun into the railgun, forms a conducting plasma-arc armature immediately behind the pellet allowing for fuseless operation of the railgun. Study of the pressure profile and the behavior of the plasma-arc armature inside the railgun bore led to elimination of spurious arcing, which prevents operation of the railgun at high voltages (and, therefore, at high currents). A timing circuit that can automatically measure the pellet input velocity and allows for accurate control of arc initiation behind the pellet helps prevent pellet disintegration and mistriggering of the arc initiation circuit. Results from the recent cryogenic operation of the two-stage pellet acceleration system are reported. 11 refs., 2 figs., 1 tab.

  17. Remote Visual Inspection Of Nuclear Fuel Pellets With Fiber Optics And Video Image Processing

    Moore, Frank W.

    1987-02-01

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

  18. Observation of cross-field transport of pellet plasmoid in LHD

    A three-dimensional observation of the solid hydrogen pellet ablation has been performed by using a fast stereo imaging camera to investigate the pellet ablation dynamics. The initial velocity component of the injected pellet is maintained during ablation in a hot plasma, and the pellet penetrates to the core plasma. On the other hand, it has been observed that part of high density pellet plasmoid, which is formed around the pellet substance by ablating hydrogen pellet, intermittently breaks away from the pellet ablating position and the breakaway plasmoid is transported across a confinement field. The breakaway plasmoid recurrently develops at the rate of about 100 times per millisecond and it is non-diffusively transported approximately 0.1 m during its several 10 μs lifetime in the opposite direction to the pellet motion, namely, toward the low magnetic field side. This observation gives a reasonable explanation for the difference between the pellet ablation position and the effective particle deposition profile. (author)

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

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

  20. Recent results on pellet physics and technology for ITER in technical university

    The main activities in pellet injection technology for tokamak plasma fueling and diagnostics presently correspond to those formulated in the ITER tasks description, which includes (i) the development of a continuous pellet injector with moderate injector velocity, (ii) the development of an injector allowing pellet velocities greater than 5 km/s, (iii) further improvement of the pellet ablation model, (iv) the study of transport phenomena related to pellet injection, and (v) the development of plasma diagnostics based on both hydrogen and impurity pellet injection. This brief paper describes the work done by the group at the Technical University in St. Petersburg which is active is most of these areas. In particular, brief summaries are given for the following topics: (1) the pellet injector technology; (2) designs for cloud photography equipment to be used in ASDEX-Upgrade experiments for the photography of clouds near ablating pellets for the purpose of plasma diagnostics of magnetic field configurations; (3) work on the ablation model based on the analysis of T-10 tokamak ablation data; (4) radial transport studies based on the plasma response to pellet-injection induced perturbations; (5) longitudinal transport studies, in particular the toroidal plasma expansion observed using soft X-ray measurements on the T-10 tokamak; and (6) high-speed photography and pellet deflection analysis for rotational transform profile determination. 13 refs, 12 figs, 3 tabs

  1. Selection of white-rot fungi to formulate complex and coated pellets for Reactive Orange 165 decolourization

    Elgueta, Sebastian; Rubilar, Olga; Lima, Nelson; Diez, M. C.

    2012-01-01

    Six strains of white-rot fungi isolated from southern Chile were evaluated for their ergosterol/biomass correlation and ligninolytic potential in solid medium to formulate pellets for Reactive Orange 165 (RO165) decolourization. The fungus Anthracophyllum discolor was selected to formulate complex pellets (fungal mycelium, sawdust, and activated carbon), coated pellets (complex pellet + alginate) and simple pellets (fungal mycelium). The activity of ligninolytic enzymes (laccase, manganese pe...

  2. Use of coffee (Coffea arabica pulp for the production of briquettes and pellets for heat generation

    Robert Cubero-Abarca

    2014-10-01

    Full Text Available Coffee bean (Coffea arabica processing generates high amount of residues that are sources of environmental pollution. Therefore, an appropriate solution is needed. The objective of this study was to determine the potential of coffee pulp to produce briquettes and pellets. The study included pulp drying (using air, solar and hot air methods; the production of briquettes and pellets; the evaluation of their energy, physical and mechanical properties; and the evaluation of pellet quality using X-ray densitometry. The results showed that the pulp presented an initial moisture content of 90%, resulting in drying times of 699, 308 and 55 hours for air, solar and hot air drying, respectively, and the calorific values of the pellets and briquettes were 12,501 kJ kg-1 and 11,591 kJ kg-1, respectively. The ash content was 8.68% for the briquettes and 6.74% for the pellets. The density of the briquettes was 1,110 kg m-3, compared with 1,300 kg m-3 for the pellets. The apparent densities were 1,000 kg m-3 and 600 kg m-3 for the briquettes and pellets, respectively, and the water absorptions by the briquettes were 7.90% and 8.10% by the pellets. The maximum horizontal compression effort was 26.86 kg cm-2, measured in the pellets, compared with 4.52 kg cm-2 in the briquettes. The maximum horizontal load was 93.24 kg, measured in the briquettes, compared with 33.50 kg in the pellets. The value of the pellet durability test was 75.54%. X-ray densitometry showed that the pellet was uniform and a few cracks were observed on the pellet surface.

  3. Device for absorbing mechanical shock

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy -absorption capability

  4. Wood pellet use in Sweden. A systems approach to the residential sector

    This empirically based thesis deals with a biofuel market in a systems context with focus on Sweden. Fuel pellets is a new consumer market for wood products. Initially used mainly by large-scale heating plants, wood pellets expanded into the Swedish residential heating market in the mid 1990s. The overall aim of this work is to provide a deeper understanding of the system for small-scale use of densified wood fuels. The objective was to provide a mapping and logistic analysis of fuel and delivery chains primarily for wood pellets. The description includes both technical as well as economic and organisational aspects. The thesis in particular investigates (i) experience from practical densification operations in the past, (ii) wood pellet retailers in Sweden, (iii) wood pellet consumers in Austria, Sweden and the United States, (iv) imports of wood pellets, and (v) forecasting of pellet consumption and inventory management for wood pellet distributors. Previous international studies revealed that the availability of cheap raw materials for fuel production and the price and availability of the most important competing fuels: coal, oil and natural gas were important factors that have guided production and use of densified wood and bark fuels. A major network of wood pellet distributors was mapped. It was concluded from a survey to these retailers that the Swedish residential market was now firmly in place and that the price of wood pellets was competitive with prices of traditional national fuels. A majority of pellet users in Austria, Sweden and the United States were pleased with pellet heating. One way to improve pellet distribution systems would be to optimise inventory management. An internal model for optimising inventory management, Pell-Sim, was constructed. For Sweden, wood pellets in 1997 represented the second most traded biofuel assortment, with 4.35 PJ or 18% of the total biofuel imports. Contrary to trade with other biofuel assortments, wood pellet trade

  5. Feeding on copepod fecal pellets: a new trophic role of dinoflagellates as detritivores

    Poulsen, Louise K.; Moldrup, M.; Berge, T.; Hansen, P.J.

    2011-01-01

    dinoflagellates (3 species) using a combination of classic incubation experiments and video recordings of feeding behavior. Fecal pellets were produced by adult Acartia tonsa feeding on Rhodomonas salina. Two mixotrophic species (Karlodinium armiger, a gymnodinoid dinoflagellate, Gy1) and all heterotrophic......Recent field studies indicate that dinoflagellates are key degraders of copepod fecal pellets. This study is the first to publish direct evidence of pellet grazing by dinoflagellates. Feeding and growth on copepod fecal pellets were studied for both heterotrophic (4 species) and mixotrophic.......3 ml cell−1 d−1 were obtained for G. spirale and P. depressum, respectively. Pellet feeding resulted in average growth rates of 0.69 and 0.08 d−1 with growth yields of 0.58 and 0.50 for G. spirale and P. depressum. Important factors for the grazing impact of the dinoflagellates on fecal pellets in this...

  6. Quality control of wood pellets in small-scale distribution and handling

    Quality control of wood pellets through the whole production, distribution and handling chain is of significance when trying to increase the small-scale use of wood pellets and to improve the competitiveness of the pellet branch. In order to improve the quality of pellets, the critical sites of different stages of production, distribution and handling, in which the pellet properties may change unfavourable for combustion, will be identified. The project will also produce data on physical and mechanical properties of pellets for the development of production, distribution and handling methods. The results will give basis for determination methods, and quality requirements and control for the needs of the Finnish market and for exports. (orig.)

  7. Use of implantable pellets to administer low levels of methyl mercury to fish

    Arnold, B.S.; Jagoe, C.H.; Gross, T.S.

    1999-07-01

    Implantable pellets of methyl mercury chloride were tested in Nile Tilapia (oreochromis niloticus) to appraise the effectiveness of the method for chronic studies of mercury. Two dosing regimes of 15 and 1.5 grams/CH{sub 3}HgCl pellet (test 1) and 1 and 0.1 grams/pellet (tests 2--3) of methyl mercury chloride were used in three tests. Additional pellets containing only matrix were used as controls. The pellets were inserted into the peritoneal cavity along with a microchip for identification. Three methods of incision closure: sutures and two types of surgical glue, were tested. Pellets used in test one released the dose too fast, resulting in premature death of the fish. Results from tests 2 and 3 show blood mercury concentrations over time and tissue levels at necropsy consistent with dose suggestion that this is a viable method of dosing fish.

  8. Experimental test of 6 mm diameter D2 pellets produced by in situ condensation

    A prototype single-shot pneumatic pellet injector has been developed in collaboration between JET and EURATOM-CEA association. The main objective of this work is to test the mechanical properties of pellets produced by in-situ condensation, mainly with regard to the maximum acceleration they are able to sustain without being broken. 6 mm diameter D2 pellets are produced and accelerated with compressed hydrogen gas delivered by a fast valve with 100 bar internal pressure. The length of the barrel is 0.5 m. At this stage of the experiment, pellets have been submitted to initial acceleration values up to 3.5 106 m/s2 without apparent problem. Experiments remain to be made in order to test the pellets for higher initial acceleration values. Maximum velocity reached by the pellets is around 1390 m/s

  9. A study of friction and axial effects in pellet-clad mechanical interaction

    An analysis is made of the effect of friction and axial forces along the fuel rod in the pellet-cladding mechanical interaction in a commercial reactor under a power-up ramp. The effect of different pellet and rod shapes on their behaviour was also determined. A linear thermoelastic computer program was used in order to obtain the stiffness matrix of a compound structure from the stiffness of its components. Pellet-cladding displacements, localized deformations of the cladding in the interfaces between pellets, as well as pellet and cladding axial deformations were determined for different power axial profiles as well as for pellets with and without dishing and with height/diameter ratios of 1.7, 1 and 0.5. (M.E.L.)

  10. density and microstructure studies of UO2 pellets at different pressing densities

    Uranium dioxide (UO2) used in nuclear reactor is a ceramic material. Urania has a high melting point, so it can not be produced via powder metallurgical methods. Pellets were pressed at KWU with densities 5, 5.5 and 6 g/cm''3 using DORST press. They were obtained by arranging only the press stroke height since the UO2 powder used had a uniform bulk density. These UO2 pellets were sintered using high temperature sintering and low temperature sintering methods. The sintered pellets densities and microstructures were examined. Pellets produced using low temperature method exhibited bimodal grain structure, while the pellets produced using high temperature method exhibited monomodal grain structure. Although there were differences in microstructure all the pellets had same densities

  11. Monitoring of a wide range of organic micropollutants on the Portuguese coast using plastic resin pellets.

    Mizukawa, Kaoruko; Takada, Hideshige; Ito, Maki; Geok, Yeo Bee; Hosoda, Junki; Yamashita, Rei; Saha, Mahua; Suzuki, Satoru; Miguez, Carlos; Frias, João; Antunes, Joana Cepeda; Sobral, Paula; Santos, Isabelina; Micaelo, Cristina; Ferreira, Ana Maria

    2013-05-15

    We analyzed polychlorinated biphenyls (PCBs), dichlorodiphenyl dichloroethane and its metabolites, hexachlorocyclohexanes (HCHs), polycyclic aromatic hydrocarbons (PAHs), and hopanes, in plastic resin pellets collected from nine locations along the Portuguese coast. Concentrations of a sum of 13 PCBs were one order of magnitude higher in two major cities (Porto: 307 ng/g-pellet; Lisboa: 273 ng/g-pellet) than in the seven rural sites. Lower chlorinated congeners were more abundant in the rural sites than in the cities, suggesting atmospheric dispersion. At most of the locations, PAH concentrations (sum of 33 PAH species) were ∼100 to ∼300 ng/g-pellet; however, three orders of magnitude higher concentrations of PAHs, with a petrogenic signature, were detected at a small city (Sines). Hopanes were detected in the pellets at all locations. This study demonstrated that multiple sample locations, including locations in both urban and remote areas, are necessary for country-scale pellet watch. PMID:23499535

  12. [Absorbed doses in dental radiology].

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk. PMID:8966249

  13. Bioswirl: A Wood Pellet Burner for Oil Retrofit

    Ljungdahl, Boo; Lundberg, Henrik [TPS Termiska Processer AB, Nykoeping (Sweden)

    2002-11-01

    A compact and robust firing system for wood pellets has been developed and its operation demonstrated during one season. The firing system was developed with the aim to retrofit heat producing oil-fired burners in the range of 0.5 to 5 MW. In this power range there are severe economical restrictions on the firing systems used; operation with high availability and low emissions of unburned gases and NO{sub x} should be secured with only periodic supervision of the boiler. At the same time there are technical restrictions since, for instance, scale up of existing commercial small grate firing technique leads to an undesired volumetric increase of the pellet burner, compared to the oil-burners to be retrofitted. Here a burner system for crushed wood pellets was developed in order to increase the combustion intensity. The pellets are fed from the storage silo to a mill/crusher where the fuel is crushed to a coarse wood powder with a size distribution of 0.5 to 4 mm, which is about the same size as the original particle size distribution used for the pellet production. Thus a simple crushing mill can be used and any excess energy demand for milling is avoided. The crushed pellets are thereafter directly fed into a cyclone burner. The centrifugal forces assure a sufficient residence time to complete thermal conversion of the large wood particles in the burner, i.e. the particles are large compared to pulverised fuel. The burner is designed with secondary -and tertiary air registers for a staged air supply and connected to a furnace in which the final burn out of combustible gases takes place. This results in an efficient burn out and low NO, emissions even at turn down ratios in the order of 1:8. Ash particles will follow the exhaust gas as fly ash. During the heating season 2001-2002 the Bioswirl burner has been demonstrated in a small-scale district heating system. A 1200 kW oil burner has been replaced with an 800 kW Bioswirl burner. The system has been operated with

  14. Structured Metal Film as Perfect Absorber

    Xiong, Xiang; Jiang, Shang-Chi; Peng, Ru-Wen; Wang, Mu

    2014-03-01

    With standing U-shaped resonators, fish-spear-like resonator has been designed for the first time as the building block to assemble perfect absorbers. The samples have been fabricated with two-photon polymerization process and FTIR measurement results support the effectiveness of the perfect absorber design. In such a structure the polarization-dependent resonance occurs between the tines of the spears instead of the conventional design where the resonance occurs between the metallic layers separated by a dielectric interlayer. The incident light neither transmits nor reflects back which results in unit absorbance. The power of light is trapped between the tines of spears and finally be absorbed. The whole structure is covered with a continuous metallic layer with good thermo-conductance, which provides an excellent approach to deal with heat dissipation, is enlightening in exploring metamaterial absorbers.

  15. ANL Advanced Photon Source crotch absorber design

    The ANL 7-GeV Advanced Photon Source storage ring crotch absorber will be subjected to a very high photon loading power density, approximately 750 W/mm2 at normal incidence. To accommodate this high heat load, two designs were studied: one is a V-type compound angle absorber and the other is a horizontally rotated plate absorber. For both models, thermal and structural analyses have been carried out using 3-D finite element analysis. The analysis indicates that the V-type compound angle absorber controlled the peak temperatures effectively within the given geometric constraints. Test samples made of GlidCop AL 15 (alumina dispersion strengthened copper) were evaluated with an electron beam welder. The predicted and measured temperatures were in reasonable agreement. The overall absorber design includes a perforated screen in the positron beam area of the storage ring vacuum chamber to reduce RF impedance and to provide pumping access for the high local gas load

  16. A state-of-the-art report on the development of B{sub 4}C materials as neutron absorbers

    Jung, Choong Hwan; Kim, Sun Jae; Park, Jee Yun; Kang, Dae Kab [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-01-01

    Boron of 10 atomic weight is one of the best neutron absorbing elements. Among the boron compounds, B{sub 4}C and its composites exhibit excellent material properties. Those materials absorb thermal and fast neutrons, are thermally and chemically very stable, and are very strong in mechanical properties. By neutron irradiation B-10 transforms into Li releasing one He atom. This He release causes swelling, cracking and fragmentation of B{sub 4}C bulks and results in degradation of the materials. The essence of technical developments of B{sub 4}C-based neutron absorbers is the minimization of the effects of He release, and this can be realized through microstructural optimizations of grain and porosity distributions. While pure B{sub 4}C is very difficult in sintering, new neutron absorbing materials of B{sub 4}C-cermets are being developed. B{sub 4}C-cermets are composite materials in which B{sub 4}C powders are dispersed in the metal matrix of Al or Cu. Those materials show easiness in sintering, mechanical forming, and B{sub 4}C content controlling. Neutron absorbing and shielding materials play an important role for the safety of reactor operations and environmental protections. Those materials are being used as monolithic pellets for control rods, burnable poison fuel rods, rack materials for spent fuel storages, shielding materials for shipping casks, and especially for shielding plates for liquid metal reactors. 37 figs., 12 tabs., 41 refs. (Author).

  17. Attractiveness and Feeding Ability of Coccinella sp. on Pellet Added Natural Preservative

    Agus, Nurariaty; Daud, Itji Diana; Amin, Nur; Ngatimin, Sri Nuraminah

    2015-01-01

    ABSTRACT Pellet is an artificial diet formulations as a supplement to predators Coccinella sp. The addition of preservatives will increase pellet durability and might affect the feeding ability of predators. The study was conducted at the Pests Laboratory, Faculty of Agriculture , Hasanuddin University, aims to determine the effect of natural preservative in pellets to the attractiveness and feeding ability of Coccinella sp. The experiment was arranged in completely randomized design , c...

  18. Pellet fuelling of plasmas with ELM mitigation by resonant magnetic perturbations in MAST

    Valovic, M.; Cunningham, G.; Garzotti, L.; Gurl, C; Kirk, A.; Naylor, G.; Patel, A; Scannell, R.; Thornton, A. J.; team, on behalf of the MAST

    2013-01-01

    Shallow fuelling pellets are injected from the high field side into plasmas in which ELMs have been mitigated using external magnetic perturbation coils. The data are compared with ideal assumptions in the ITER fuelling model, namely that mitigated ELMs are not affected by fuelling pellets. Firstly it is shown that during the pellet evaporation an ELM is triggered, during which the amount particle loss could be larger (factor ~1.5) than the particle loss during an ELM which was not induced by...

  19. Study of Advanced Railgun Hydrogen Pellet Injectors for Fusion Reactor Refueling.

    King, Tony Levone

    An advanced railgun system has been developed to assess its feasibility as a hypervelocity hydrogen pellet injector for magnetically confined plasmas. It consists of a pellet generator/gas gun assembly for freezing hydrogen pellets and injecting them into the railgun at velocities as high as 1.5 km/s. A plasma armature is formed by ionizing the low-Z propellant gas behind the pellet and firing the railgun. This fuseless operation prevents high-Z impurities from entering the reactor during pellet injection. The railgun system has several features that distinguish it from its predecessors, including: (1) a more compact, versatile pellet generator, (2) a new gas gun configuration that produces significantly higher pellet speeds, (3) a perforated coupling piece between the gas gun and railgun to prevent spurious arcing, and (4) ablation-resistant sidewalls, perforated sidewalls and transaugmentation to reduce inertial and viscous drag, the primary obstacles to achieving hypervelocity. A unique system of sophisticated controls and diagnostics has been assembled to operate the railgun system and assess its performance, including fully automated pellet freezing and gas gun operation, an automatic timing circuit that is immune to mistriggering caused by pellet fragmentation or electromagnetic interference, a streak camera, photostations, light gates, current trans formers, B-dot probes, laser interferometry and optical spectroscopy. Free-arc and hydrogen pellet experiments were conducted to evaluate various railgun designs. Transaugmented and simple railguns 1.2 and 2 m long were tested. The performances of railguns using Mullite, solid Lexan and perforated Lexan sidewalls were compared. The railgun theory of operation and anticipated losses are also examined. The theoretical predictions are found to be in good agreement with the experimental results. The advanced railgun system has set several world records for bare hydrogen pellet velocity, including a 3.3 km/s shot on

  20. Growth of Agaricus campestris NRRL 2334 in the Form of Pellets

    Martin, Antonio M.; Bailey, Valerie I.

    1985-01-01

    The production of pellets of the fungus Agaricus campestris NRRL 2334 was studied in submerged fermentation with peat extract as the main substrate source. Pellets up to 6 mm in diameter were obtained when the peat extract was diluted to reduce the concentration of growth inhibitors. Yeast extract and yeast extract plus glucose were the most effective nutrient supplements in the diluted peat extract media and stimulated the formation of large pellets which contained 44.4% crude protein, 2.8% ...