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Sample records for debris bed formation

  1. Investigation of debris bed formation, spreading and coolability

    Energy Technology Data Exchange (ETDEWEB)

    Kudinov, P.; Konovalenko, A.; Grishchenko, D.; Yakush, S.; Basso, S.; Lubchenko, N.; Karbojian, A. [Royal Institute of Technology, KTH. Div. of Nuclear Power Safety, Stockholm (Sweden)

    2013-08-15

    The work is motivated by the severe accident management strategy adopted in Nordic type BWRs. It is assumed that core melt ejected from the vessel will fragment, quench and form a coolable debris bed in a deep water pool below the vessel. In this work we consider phenomena relevant to the debris bed formation and coolability. Several DEFOR-A (Debris Bed Formation - Agglomeration) tests have been carried out with new corium melt material and a melt releasing nozzle mockup. The influence of the melt material, melt superheat, jet free fall height on the (i) faction of agglomerated debris, (ii) particle size distribution, (iii) ablation/plugging of the nozzle mockup has been addressed. Results of the DECOSIM (Debris Coolability Simulator) code validation against available COOLOCE data are presented in the report. The dependence of DHF on system pressure from COOLOCE experiments can be reproduced quite accurately if either the effective particle diameter or debris bed porosity is increased. For a cylindrical debris bed, good agreement is achieved in DECOSIM simulations for the particle diameter 0.89 mm and porosity 0.4. The results obtained are consistent with MEWA simulation where larger particle diameters and porosities were found to be necessary to reproduce the experimental data on DHF. It is instructive to note that results of DHF prediction are in better agreement with POMECO-HT data obtained for the same particles. It is concluded that further clarification of the discrepancies between different experiments and model predictions. In total 13 exploratory tests were carried out in PDS (particulate debris spreading) facility to clarify potential influence of the COOLOCE (VTT) facility heaters and TCs on particle self-leveling process. Results of the preliminary analysis suggest that there is no significant influence of the pins on self-leveling, at least for the air superficial velocities ranging from 0.17 up to 0.52 m/s. Further confirmatory tests might be needed

  2. Investigation of debris bed formation, spreading and coolability

    International Nuclear Information System (INIS)

    Kudinov, P.; Konovalenko, A.; Grishchenko, D.; Yakush, S.; Basso, S.; Lubchenko, N.; Karbojian, A.

    2013-08-01

    The work is motivated by the severe accident management strategy adopted in Nordic type BWRs. It is assumed that core melt ejected from the vessel will fragment, quench and form a coolable debris bed in a deep water pool below the vessel. In this work we consider phenomena relevant to the debris bed formation and coolability. Several DEFOR-A (Debris Bed Formation - Agglomeration) tests have been carried out with new corium melt material and a melt releasing nozzle mockup. The influence of the melt material, melt superheat, jet free fall height on the (i) faction of agglomerated debris, (ii) particle size distribution, (iii) ablation/plugging of the nozzle mockup has been addressed. Results of the DECOSIM (Debris Coolability Simulator) code validation against available COOLOCE data are presented in the report. The dependence of DHF on system pressure from COOLOCE experiments can be reproduced quite accurately if either the effective particle diameter or debris bed porosity is increased. For a cylindrical debris bed, good agreement is achieved in DECOSIM simulations for the particle diameter 0.89 mm and porosity 0.4. The results obtained are consistent with MEWA simulation where larger particle diameters and porosities were found to be necessary to reproduce the experimental data on DHF. It is instructive to note that results of DHF prediction are in better agreement with POMECO-HT data obtained for the same particles. It is concluded that further clarification of the discrepancies between different experiments and model predictions. In total 13 exploratory tests were carried out in PDS (particulate debris spreading) facility to clarify potential influence of the COOLOCE (VTT) facility heaters and TCs on particle self-leveling process. Results of the preliminary analysis suggest that there is no significant influence of the pins on self-leveling, at least for the air superficial velocities ranging from 0.17 up to 0.52 m/s. Further confirmatory tests might be needed

  3. Two-Phase Flow Effect on the Ex-Vessel Corium Debris Bed Formation in Severe Accident

    International Nuclear Information System (INIS)

    Kim, Eunho; Park, Jin Ho; Kim, Moo Hwan; Park, Hyun Sun; Ma, Weimin; Bechta, Sevostian V.

    2014-01-01

    In Korean IVR-ERVC(In-Vessel Retention of molten corium through External Reactor Vessel Cooling) strategy, if the situation degenerates into insufficient external vessel cooling, the molten core mixture can directly erupt into the flooded cavity pool from the weakest point of the vessel. Then, FCI (molten Fuel Coolant Interaction) will fragment the corium jet into small particulates settling down to make porous debris bed on the cavity basemat. To secure the containment integrity against the MCCI (Molten Core - Concrete Interaction), cooling of the heat generating porous corium debris bed is essential and it depends on the characteristics of the bed itself. For the characteristics of corium debris bed, many previous experimental studies with simulant melts reported the heap-like shape mostly. There were also following experiments to develop the correlation for the heap-like shaped debris bed. However, recent studies started to consider the effect of the decay heat and reported some noticeable results with the two-phase flow effect on the debris bed formation. The Kyushu University and JAEA group reported the experimental studies on the 'self-leveling' effect which is the flattening effect of the particulate bed by the inside gas generation. The DECOSIM simulation study of RIT (Royal Institute of Technology, Sweden) with Russian researchers showed the 'large cavity pool convection' effect, which is driven by the up-rising gas bubble flow from the pre-settled debris bed, on the particle settling trajectories and ultimately final bed shape. The objective of this study is verification of the two-phase flow effect on the ex-vessel corium debris bed formation in the severe accident. From the analysis on the test movie and resultant particle beds, the two-phase flow effect on the debris bed formation, which has been reported in the previous studies, was verified and the additional findings were also suggested. For the first, in quiescent pool the

  4. Investigation of flow regime in debris bed formation behavior with nonspherical particles

    Directory of Open Access Journals (Sweden)

    Songbai Cheng

    2018-02-01

    Full Text Available It is important to clarify the characteristics of flow regimes underlying the debris bed formation behavior that might be encountered in core disruptive accidents of sodium-cooled fast reactors. Although in our previous publications, by applying dimensional analysis technique, an empirical model, with its reasonability confirmed over a variety of parametric conditions, has been successfully developed to predict the regime transition and final bed geometry formed, so far this model is restricted to predictions of debris mixtures composed of spherical particles. Focusing on this aspect, in this study a new series of experiments using nonspherical particles have been conducted. Based on the knowledge and data obtained, an extension scheme is suggested with the purpose of extending the base model to cover the particle-shape influence. Through detailed analyses and given our current range of experimental conditions, it is found that, by coupling the base model with this scheme, respectable agreement between experiments and model predictions for the regime transition can be achieved for both spherical and nonspherical particles. Knowledge and evidence from our work might be utilized for the future improvement of design of an in-vessel core catcher as well as the development and verification of sodium-cooled fast reactor severe accident analysis codes in China.

  5. Simulant - water experiments to characterize the debris bed formed in severe core melt accidents

    International Nuclear Information System (INIS)

    Mathai, Amala M.; Anandan, J.; Sharma, Anil Kumar; Murthy, S.S.; Malarvizhi, B.; Lydia, G.; Das, Sanjay Kumar; Nashine, B.K.; Selvaraj, P.

    2015-01-01

    Molten Fuel Coolant Interaction (WO) and debris bed configuration on the core catcher plate assumes importance in assessing the Post Accident Heat Removal (PARR) of a heat generating debris bed. The key factors affecting the coolability of the debris bed are the bed porosity, morphology of the fragmented particles, degree of spreading/heaping of the debris on the core catcher and the fraction of lump formed. Experiments are conducted to understand the fragmentation kinetics and subsequent debris bed formation of molten woods metal in water at interface temperatures near the spontaneous nucleation temperature of water. Morphology of the debris particles is investigated to understand the fragmentation mechanisms involved. The spreading behavior of the debris on the catcher plate and the particle size distribution are presented for 5 kg and 10 kg melt inventories. Porosity of the undisturbed bed on the catcher plate is evaluated using a LASER sensor technique. (author)

  6. Flow characteristics of counter-current flow in debris bed

    International Nuclear Information System (INIS)

    Abe, Yutaka; Adachi, Hiromichi

    2004-01-01

    In the course of a severe accident, a damaged core would form a debris bed consisting of once-molten and fragmented fuel elements. It is necessary to evaluate the dryout heat flux for the judgment of the coolability of the debris bed during the severe accident. The dryout phenomena in the debris bed is dominated by the counter-current flow limitation (CCFL) in the debris bed. In this study, air-water counter-current flow behavior in the debris bed is experimentally investigated with glass particles simulating the debris beds. In this experiment, falling water flow rate and axial pressure distributions were experimentally measured. As the results, it is clarified that falling water flow rate becomes larger with the debris bed height and the pressure gradient in the upper region of the debris bed is different from that in the lower region of the debris bed. These results indicate that the dominant region for CCFL in the debris bed is identified near the top of the debris bed. Analytical results with annular flow model indicates that interfacial shear stress in the upper region of the debris bed is larger than that in the lower region of the debris bed. (author)

  7. Thermal-hydraulic and characteristic models for packed debris beds

    International Nuclear Information System (INIS)

    Mueller, G.E.; Sozer, A.

    1986-12-01

    APRIL is a mechanistic core-wide meltdown and debris relocation computer code for Boiling Water Reactor (BWR) severe accident analyses. The capabilities of the code continue to be increased by the improvement of existing models. This report contains information on theory and models for degraded core packed debris beds. The models, when incorporated into APRIL, will provide new and improved capabilities in predicting BWR debris bed coolability characteristics. These models will allow for a more mechanistic treatment in calculating temperatures in the fluid and solid phases in the debris bed, in determining debris bed dryout, debris bed quenching from either top-flooding or bottom-flooding, single and two-phase pressure drops across the debris bed, debris bed porosity, and in finding the minimum fluidization mass velocity. The inclusion of these models in a debris bed computer module will permit a more accurate prediction of the coolability characteristics of the debris bed and therefore reduce some of the uncertainties in assessing the severe accident characteristics for BWR application. Some of the debris bed theoretical models have been used to develop a FORTRAN 77 subroutine module called DEBRIS. DEBRIS is a driver program that calls other subroutines to analyze the thermal characteristics of a packed debris bed. Fortran 77 listings of each subroutine are provided in the appendix

  8. PIV Visualization of Bubble Induced Flow Circulation in 2-D Rectangular Pool for Ex-Vessel Debris Bed Coolability

    Energy Technology Data Exchange (ETDEWEB)

    Han, Teayang; Kim, Eunho; Park, Hyun Sun; Moriyama, Kiyofumi [POSTECH, Pohang (Korea, Republic of)

    2015-10-15

    The previous research works demonstrated the debris bed formation on the flooded cavity floor in experiments. Even in the cases the core melt is once solidified, the debris bed can be re-melted due to the decay heat. If the debris bed is not cooled enough by the coolant, the re-melted debris bed will react with the concrete base mat. This situation is called the molten core-concrete interaction (MCCI) which threatens the integrity of the containment by generated gases which pressurize the containment. Therefore securing the long term coolability of the debris bed in the cavity is crucial. According to the previous research works, the natural convection driven by the rising bubbles affects the coolability and the formation of the debris bed. Therefore, clarification of the natural convection characteristics in and around the debris bed is important for evaluation of the coolability of the debris bed. In this study, two-phase flow around the debris bed in a 2D slice geometry is visualized by PIV method to obtain the velocity map of the flow. The DAVINCI-PIV was developed to investigate the flow around the debris bed. In order to simulate the boiling phenomena induced by the decay heat of the debris bed, the air was injected separately by the air chamber system which consists of the 14 air-flowmeters. The circulation flow developed by the rising bubbles was visualized by PIV method.

  9. Melt propagation in dry core debris beds

    International Nuclear Information System (INIS)

    Dosanjh, S.S.

    1989-01-01

    During severe light water reactor accidents like Three Mile Island Unit 2, the fuel rods can fragment and thus convert the reactor core into a large particle bed. The postdryout meltdown of such debris beds is examined. A two-dimensional model that considers the presence of oxidic (UO 2 and ZrO 2 ) as well as metallic (e.g., zirconium) constituents is developed. Key results are that a dense metallic crust is created near the bottom of the bed as molten materials flow downward and freeze; liquid accumulates above the blockage and, if zirconium is present, the pool grows rapidly as molten zirconium dissolved both UO 2 and ZrO 2 particles; if the melt wets the solid, a fraction of the melt flows radially outward under the action of capillary forces and freezes near the radial boundary; in a nonwetting system, all of the melt flows into the bottom of the bed; and when zirconium and iron are in intimate contact and the zirconium metal atomic fraction is > 0.33, these metals can liquefy and flow out of the bed very early in the meltdown sequence

  10. Debris Disks: Probing Planet Formation

    OpenAIRE

    Wyatt, Mark C.

    2018-01-01

    Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km i...

  11. Investigation of the structure of debris beds formed from fuel rods fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Duc-Hanh; Fichot, Florian; Topin, Vincent, E-mail: vincent.topin@irsn.fr

    2017-03-15

    This paper is a study of debris beds that can form in the core of a nuclear power plant under severe accident conditions. Such beds are formed of fragments of pellets and cladding remnants, as observed in the TMI-2 core. Many important issues are related with the morphology of those debris beds: are they coolable in case of water injection and how does molten corium progress through them if they are not coolable? The answers to those questions depend on the structure of the debris bed: porosity, number and arrangement of particles. In order to obtain relevant information, a numerical simulation of the formation of the debris bed is proposed. It relies on a granular approach of the type called “Contact Dynamics” to simulate the collapse of debris and their accumulation. Two different schemes of fuel pellet fragmentation are considered and simulations for different degrees of fragmentation of the pellets are performed. The results show that the number of axial cracks on fuel pellets strongly influences the final porosity of the debris bed. Porosities vary between 31% (less coolable cases) and 45% (similar to TMI-2 observations), with a most probable configuration around 41%. The specific surface of the bed is also evaluated. In the last part, a simple model is used to estimate the impact of the variation in geometry of the numeric debris beds on their flow properties. We show that the permeability and passability can vary respectively with a range of 30% and 15% depending on the number of fragment per pellet. The other benefits of the approach are finally discussed. Among them, the possibility to print 3D samples from the calculated images of debris beds appears as a promising perspective to perform experiments with realistic debris beds.

  12. The effect of self-leveling on debris bed coolability under severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Basso, S.; Konovalenko, A. [Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullsbacken 21, D5, Stockholm 106 91 (Sweden); Yakush, S.E. [Institute for Problems in Mechanics of the Russian Academy of Sciences, Ave. Vernadskogo 101 Bldg 1, Moscow 119526 (Russian Federation); Kudinov, P. [Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullsbacken 21, D5, Stockholm 106 91 (Sweden)

    2016-08-15

    Highlights: • A model for coolability of a self-leveling, variable-shape debris bed is proposed. • Sensitivity analysis is performed to screen out the less influential input parameters. • A small fraction of scenarios has initially a non-coolable debris bed configuration. • The fraction of non-coolable scenarios decreases with time due to self-leveling. - Abstract: Nordic-type boiling water reactors employ melt fragmentation, quenching, and long term cooling of the debris bed in a deep pool of water under the reactor vessel as a severe accident (SA) mitigation strategy. The height and shape of the bed are among the most important factors that determine if decay heat can be removed from the porous debris bed by natural circulation of water. The debris bed geometry depends on its formation process (melt release, fragmentation, sedimentation and settlement on the containment basemat), but it also changes with time afterwards, due to particle redistribution promoted by coolant flow (self-leveling). The ultimate goal of this work is to develop an approach to the assessment of the probability that debris in such a variable-shape bed can reach re-melting (which means failure of SA mitigation strategy), i.e. the time necessary for the slumping debris bed to reach a coolable configuration is larger than the time necessary for the debris to reach the re-melting temperature. For this purpose, previously developed models for particulate debris spreading by self-leveling and debris bed dryout are combined to assess the time necessary to reach a coolable state and evaluate its uncertainty. Sensitivity analysis was performed to screen out less important input parameters, after which Monte Carlo simulation was carried out in order to collect statistical characteristics of the coolability time. The obtained results suggest that, given the parameters ranges typical of Nordic BWRs, only a small fraction of debris beds configurations exhibits the occurrence of dryout. Of the

  13. Preliminary results from initial in-pile debris bed experiments

    International Nuclear Information System (INIS)

    Rivard, J.B.

    1977-01-01

    An accident in a liquid metal fast breeder reactor (LMFBR) in which molten core material is suddenly quenched with subcooled liquid sodium could result in extensive fragmentation and dispersal of fuel as subcritical beds of frozen particulate debris within the reactor vessel. Since this debris will continue to generate power due to decay of retained fission products, containment of the debris is threatened if the generated heat is not removed. Therefore, the initial safety question is the capacity which debris beds may have for transfer of the decay heat to overlying liquid sodium by natural processes--i.e., without the aid of forced circulation of the coolant. Up to the present time, all experiments on debris bed behavior either have used substitute materials (e.g., sand and water) or have employed actual materials, but atypical heating methods. Increased confidence in the applicability of debris bed simulations is afforded if the heat is generated within the fuel component of the appropriate fast reactor materials. The initial series of in-pile tests reported on herein constitutes the first experiments in which the internal heating mode has been produced in particulate oxide fuel immersed in liquid sodium. Fission heating of the fully-enriched UO 2 in the experiment while it is contained within Sandia Laboratories Annular Core Pulse Reactor (ACPR), operating in its steady-state mode, approximates the decay heating of debris. Preliminary results are discussed

  14. Experimental study of self-leveling behavior in debris bed

    International Nuclear Information System (INIS)

    Zhang, Bin; Harada, Tetsushi; Hirahara, Daisuke; Matsumoto, Tatsuya; Morita, Koji; Fukuda, Kenji; Yamano, Hidemasa; Suzuki, Tohru; Tobita, Yoshiharu

    2008-01-01

    After a core disruptive accident in a sodium-cooled fast reactor, core debris may settle on locations such as within the core-support structure or in the lower inlet plenum of the reactor vessel as debris beds, as a consequence of rapid quenching and fragmentation of core materials in subcooled sodium. The particle beds that are initially of varying depth have been observed to undergo a process of self-leveling when sodium boiling occurs within the beds. The boiling is believed to provide the driven force with debris needed to overcome resisting forces. Self-leveling ability has much effect on heat-removal capability of debris beds. In the present study, characteristics of self-leveling behaviors were investigated experimentally with simulant materials. Although the decay heat from fuel debris drives the coolant boiling in reactor accident conditions, the present experiments employed depressurization boiling of water to simulate axially increasing void distribution in a debris bed, which consists of solid particles of alumina or lead with different density. The particle size (from 0.5 mm to 6 mm in diameter) and shape (spherical or non-spherical particles) were also taken as experimental parameters. A rough criteria for self-leveling occurrence is proposed and compared with the experimental results. Characteristics of the self-leveling behaviors observed are analyzed and extrapolate to reactor accident conditions. (author)

  15. Design report on SCDAP/RELAP5 model improvements - debris bed and molten pool behavior

    International Nuclear Information System (INIS)

    Allison, C.M.; Rempe, J.L.; Chavez, S.A.

    1994-11-01

    The SCDAP/RELAP5/MOD3 computer code is designed to describe the overall reactor coolant system thermal-hydraulic response, core damage progression, and in combination with VICTORIA, fission product release and transport during severe accidents. Improvements for existing debris bed and molten pool models in the SCDAP/RELAP5/MOD3.1 code are described in this report. Model improvements to address (a) debris bed formation, heating, and melting; (b) molten pool formation and growth; and (c) molten pool crust failure are discussed. Relevant data, existing models, proposed modeling changes, and the anticipated impact of the changes are discussed. Recommendations for the assessment of improved models are provided

  16. Development of an ex-vessel corium debris bed with two-phase natural convection in a flooded cavity

    International Nuclear Information System (INIS)

    Kim, Eunho; Lee, Mooneon; Park, Hyun Sun; Moriyama, Kiyofumi; Park, Jin Ho

    2016-01-01

    Highlights: • For ex-vessel severe accidents in LWRs with wet-cavity strategy, development of debris bed with two-phase natural convection flow due to thermal characteristics of prototypic corium particles was investigated experimentally by using simulant particles and local air bubble control system. • Based on the experimental results of this study, an analytical model was established to describe the spreading of the debris bed in terms of two-phase flow and the debris injection parameters. • This model was then used to analyze the formation of debris beds at the reactor scale, and a sensitivity analysis was carried out based on key accident parameters. - Abstract: During severe accidents of light water reactors (LWRs), the coolability of relocated corium from the reactor vessel is a significant safety issue and a threat to the integrity of containment. With a flooded cavity, a porous debris bed is expected to develop on the bottom of the pool due to breakup and fragmentation of the melt jet. As part of the coolability assessment under accident conditions, the geometrical configuration of the debris bed is important. The Debris Bed Research Apparatus for Validation of the Bubble-Induced Natural Convection Effect Issue (DAVINCI) experimental apparatus facility was constructed to investigate the formation of debris beds under the influence of a two-phase flow induced by steam generation due to the decay heat of the debris bed. Using this system, five kilograms of stainless steel simulant debris were injected from the top of the water level, while air bubbles simulating the vapor flow were injected from the bottom of the particle catcher plate. The airflow rate was determined based on the quantity of settled debris, which will form a heat source due to the decay of corium. The radial distribution of the settled debris was examined using a ‘gap–tooth’ approach. Based on the experimental results of this study, an analytical model was established to

  17. Development of an ex-vessel corium debris bed with two-phase natural convection in a flooded cavity

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eunho; Lee, Mooneon; Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr; Moriyama, Kiyofumi; Park, Jin Ho

    2016-03-15

    Highlights: • For ex-vessel severe accidents in LWRs with wet-cavity strategy, development of debris bed with two-phase natural convection flow due to thermal characteristics of prototypic corium particles was investigated experimentally by using simulant particles and local air bubble control system. • Based on the experimental results of this study, an analytical model was established to describe the spreading of the debris bed in terms of two-phase flow and the debris injection parameters. • This model was then used to analyze the formation of debris beds at the reactor scale, and a sensitivity analysis was carried out based on key accident parameters. - Abstract: During severe accidents of light water reactors (LWRs), the coolability of relocated corium from the reactor vessel is a significant safety issue and a threat to the integrity of containment. With a flooded cavity, a porous debris bed is expected to develop on the bottom of the pool due to breakup and fragmentation of the melt jet. As part of the coolability assessment under accident conditions, the geometrical configuration of the debris bed is important. The Debris Bed Research Apparatus for Validation of the Bubble-Induced Natural Convection Effect Issue (DAVINCI) experimental apparatus facility was constructed to investigate the formation of debris beds under the influence of a two-phase flow induced by steam generation due to the decay heat of the debris bed. Using this system, five kilograms of stainless steel simulant debris were injected from the top of the water level, while air bubbles simulating the vapor flow were injected from the bottom of the particle catcher plate. The airflow rate was determined based on the quantity of settled debris, which will form a heat source due to the decay of corium. The radial distribution of the settled debris was examined using a ‘gap–tooth’ approach. Based on the experimental results of this study, an analytical model was established to

  18. Self-leveling onset criteria in debris beds

    International Nuclear Information System (INIS)

    Zhang, Bin; Harada, Tetsushi; Hirahara, Daisuke; Matsumoto, Tatsuya; Morita, Koji; Fukuda, Kenji; Yamano, Hidemasa; Suzuki, Tohru; Tobita, Yoshiharu

    2010-01-01

    In a core-disruptive accident of a sodium-cooled fast breeder reactor, core debris may settle on the core-support structure and/or in the lower inlet plenum of the reactor vessel because of rapid quenching and fragmentation of molten core materials in the subcooled sodium plenum. Coolant boiling is the mechanism driving the self-leveling of a debris bed that causes significant changes in the heat-removal capability of the beds. In the present study, we develop criteria establishing the onset of this self-leveling behavior that we base on a force balance model assuming a debris bed with a single-sized spherical particle. The model considers drag, buoyancy, and gravity acting on each particle. A series of experiments with simulant materials verified the applicability of this description of self-leveling. Particle size (between 0.5-6 mm), shape (spherical and nonspherical), density (namely of alumina, zirconia, lead, and stainless steel), along with boiling intensity, bed volume, and even experimental methods were taken into consideration to obtain general characteristics of the self-leveling process. We decided to use depressurization boiling to simulate an axially increasing void distribution in the debris bed, although bottom heating was also used to validate the use of the depressurization method. On the self-leveling onset issues, we obtained good agreement between model predictions and experimental results. Extrapolation of our model to actual reactor conditions is discussed. (author)

  19. Effect of particle stratification on debris-bed dryout

    International Nuclear Information System (INIS)

    Gabor, J.D.; Cassulo, J.C.; Pederson, D.R.

    1982-01-01

    Significant work has been performed on debris-bed dryout on beds of either uniformly sized particles or particles of a wide size range which are well mixed. This work has provided an understanding of the mechanisms of dryout and an empirical basis for containment analysis. However, the debris bed resulting from a HCDA would not consist of uniformly sized particles and for certain scenarios the bed could be stratified rather than well mixed. Tests have been conducted on the effect of particle size distribution on dryout and concluded that not only is the mean particle size an important parameter but also the standard deviation of the distribution and change in porosity. The D6 in-pile test at Sandia with a 114-mm deep stratified bed resulted in a reduced dryout heat flux compared to a uniformly mixed bed. Because of the many questions concerning the dryout behavior of stratified beds of wide size distribution out-of-pile experiments in which metal particles in water pools are inductively heated were initiated at Argonne

  20. Transient quenching of superheated debris beds during bottom reflood

    International Nuclear Information System (INIS)

    Tutu, N.K.; Ginsberg, T.; Klein, J.; Schwarz, C.E.; Klages, J.

    1984-01-01

    The experimental data suggest that for small liquid supply rate and low initial particle temperature, the bed quench process is a one-dimensional frontal phenomenon. The bed heat flux is constant during most of the duration of the quench period. The range of conditions which display one-dimensional frontal cooling characteristics is identified as the deep bed regime of bed quenching, and a limiting mathematical model was developed to describe the observed behavior. For large liquid supply rate and high initial bed temperature, the bed quench process is a complex phenomenon. Under these conditions, the bed heat flux displays a nonuniform time dependence. In order to characterize this shallow bed regime, it was necessary to develop a detailed transient model of the coolant-debris interaction. This model, while developed for the shallow bed regime, also applies to the deep bed regime. Numerical computations clearly demonstrate the importance of developing a general reliable model for the solid-fluid heat transfer coefficients

  1. Quench cooling of superheated debris beds in containment during LWR core meltdown accidents

    International Nuclear Information System (INIS)

    Ginsberg, T.; Chen, J.C.

    1984-01-01

    Light water reactor core meltdown accident sequence studies suggest that superheated debris beds may settle on the concrete floor beneath the reactor vessel. A model for the heat transfer processes during quench of superheated debris beds cooled by an overlying pool of water has been presented in a prior paper. This paper discusses the coolability of decay-heated debris beds from the standpoint of their transient quench characteristics. It is shown that even though a debris bed configuration may be coolable from the point of view of steady-state decay heat removal, the quench behavior from an initially elevated temperature may lead to bed melting prior to quench of the debris

  2. Experimental study on coolability of particulate core-metal debris bed with oxidization, (2). Fragmentation and enhanced heat transfer in zircaloy debris bed

    International Nuclear Information System (INIS)

    Su, Guanghui; Sugiyama, Ken-ichiro; Aoki, Hiroomi; Kimura, Iichi

    2006-01-01

    The oxidization and coolability characteristics of the particulate Zircaloy debris bed, which is deposited under the hard debris and through which first vapor penetrates and then water penetrates, are studied in the present paper. In the vapor penetration experiments, it is found that Zircaloy debris particles are effectively broken into small pieces after making thick oxidized layer with deep clacks by rapid oxidization under the condition that vapor with 20 cm/s penetrates for 30 to 70 min at an initial debris bed temperature of 1,030degC. It is also confirmed in the water penetration experiments that the oxidized particle debris bed has potentially of high coolability when water penetrates through the fully oxidized particle bed because of a high capillary force originating from those particles with deep cracks on their surfaces. Based on the present study, a new scenario for the appearance and disappearance of the hot spot in the TMI-2 accident is possible. The particulate core-metal core-metal debris bed is first heated up by rapid oxidization with heat generation when vapor can penetrate through the debris bed with porosities. This corresponds to the appearance of the hot spot. The resultant oxidized particulate debris bed causes a high coolability due to its high capillary force when the water can touch the debris bed at wet condition. This corresponds to the disappearance of the hot spot. (author)

  3. Fission-product releases from a PHWR terminal debris bed

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.J.; Bailey, D.G., E-mail: morgan.brown@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    During an unmitigated severe accident in a pressurized heavy water reactor (PHWR) with horizontal fuel channels, the core may disassemble and relocate to the bottom of the calandria vessel. The resulting heterogeneous in-vessel terminal debris bed (TDB) would likely be quenched by any remaining moderator, and some of the decay heat would be conducted through the calandria vessel shell to the surrounding reactor vault or shield tank water. As the moderator boiled off, the solid debris bed would transform into a more homogeneous molten corium pool located between top and bottom crusts. Until recently, the severe accident code MAAP-CANDU assumed that unreleased volatile and semi-volatile fission products remained in the TDB until after calandria vessel failure, due to low diffusivity through the top crust and the lack of gases or steam to flush released fission products from the debris. However, national and international experimental results indicate this assumption is unlikely; instead, high- and medium-volatility fission products would be released from a molten debris pool, and their volatility and transport should be taken into account in TDB modelling. The resulting change in the distribution of fission products within the reactor and containment, and the associated decay heat, can have significant effects upon the progression of the accident and fission-product releases to the environment. This article describes a postulated PHWR severe accident progression to generate a TDB and the effects of fission-product releases from the terminal debris, using the simple release model in the MAAP-CANDU severe accident code. It also provides insights from various experimental programs related to fission-product releases from core debris, and their applicability to the MAAP-CANDU TDB model. (author)

  4. Experimental study and modelling of pressure losses during reflooding of a debris beds

    International Nuclear Information System (INIS)

    Clavier, Remi

    2015-01-01

    This work deals with single and two-phase flow pressure losses in porous media. The aim is to improve understanding and modeling of momentum transfer inside particle beds, in relation with nuclear safety issues concerning the reflooding of debris beds during severe nuclear accidents. Indeed, the degradation of the core during such accidents can lead to the collapse of the fuel assemblies, and to the formation of a debris bed, which can be described as a hot porous medium. This thesis is included in a nuclear safety research project on coolability of debris beds during reflooding sequences. An experimental study of single and two-phase cold-flow pressure losses in particle beds is proposed. The geometrical characteristics of the debris and the hydrodynamic conditions are representative of the real case, in terms of granulometry, particle shapes, and flow velocities. The new data constitute an important contribution. In particular, they contain pressure losses and void fraction measurements in two-phase air-water flows with non-zero liquid Reynolds numbers, which did not exist before. Predictive models for pressure losses in single and two-phase flow through particle beds have been established from experimental data. Their structures are based on macroscopic equations obtained from the volume averaging of local conservation equations. Single-phase flow pressure losses can be described by a Darcy-Forchheimer law with a quadratic correction, in terms of filtration velocity, with a better-than-10 % precision. Numerical study of single-phase flows through porous media shows that this correlation is valid for disordered smooth particle beds. Two-phase flow pressure losses are described using a generalized Darcy-Forchheimer structure, involving inertial and cross flow terms. A new model is proposed and compared to the experimental data and to the usual models used in severe accident simulation codes. (author)

  5. Coarse-grained debris flow dynamics on erodible beds

    Science.gov (United States)

    Lanzoni, Stefano; Gregoretti, Carlo; Stancanelli, Laura Maria

    2017-03-01

    A systematic set of flume experiments is used to investigate the features of velocity profiles within the body of coarse-grained debris flows and the dependence of the transport sediment concentration on the relevant parameters (runoff discharge, bed slope, grain size, and form). The flows are generated in a 10 m long laboratory flume, initially filled with a layer consisting of loose debris. After saturation, a prescribed water discharge is suddenly supplied over the granular bed, and the runoff triggers a debris flow wave that reaches nearly steady conditions. Three types of material have been used in the tests: gravel with mean grain size of 3 and 5 mm, and 3 mm glass spheres. Measured parameters included: triggering water discharge, volumetric sediment discharge, sediment concentration, flow depth, and velocity profiles. The dynamic similarity with full-sized debris flows is discussed on the basis of the relevant dimensionless parameters. Concentration data highlight the dependence on the slope angle and the importance of the quasi-static friction angle. The effects of flow rheology on the shape of velocity profiles are analyzed with attention to the role of different stress-generating mechanisms. A remarkable collapse of the dimensionless profiles is obtained by scaling the debris flow velocity with the runoff velocity, and a power law characterization is proposed following a heuristic approach. The shape of the profiles suggests a smooth transition between the different rheological regimes (collisional and frictional) that establish in the upper and lower regions of the flow and is compatible with the presence of multiple length scales dictated by the type of contacts (instantaneous or long lasting) between grains.

  6. Analyses on ex-vessel debris formation and coolability in SARNET frame

    International Nuclear Information System (INIS)

    Pohlner, G.; Buck, M.; Meignen, R.; Kudinov, P.; Ma, W.; Polidoro, F.; Takasuo, E.

    2014-01-01

    Highlights: • Melt outflow varies from dripping melt outflow to molten corium jets of variable size. • Experiments show clear trend of producing particles in size range 2-4 mm. • Code calculations show complete solidification of particles, yielding formation of fragmented debris beds. • Limits of debris bed cooling and coolability margins are analysed. - Abstract: The major aim of work in the SARNET2 European project on ex-vessel debris formation and coolability was to get an overall perspective on coolability of melt released from a failed reactor pressure vessel and falling into a water-filled cavity. Especially, accident management concepts for BWRs, dealing with deep water pools below the reactor vessel, are addressed, but also shallower pools in existing PWRs, with questions about partial cooling and time delay of molten corium concrete interaction. The subject can be divided into three main topics: (i) Debris bed formation by breakup of melt, (ii) Coolability of debris and (iii) Coupled treatment of the processes. Accompanied by joint collaborations of the partners, the performed work comprises theoretical, experimental and modelling activities. Theoretical work was done by KTH on the melt outflow conditions from a RPV and on the quantification of the probability of yielding a non-coolable ex-vessel bed by use of probabilistic assessment. IKE introduced a theoretical concept to improve debris bed coolability. A large amount of experimental work was done by partners (KTH, VTT, IKE) on the coolability of debris beds using different bed geometries, particles, heating methods and water feeds, yielding a valuable base for code validation. Modelling work was mainly done by IKE, IRSN, RSE and VTT concerning jet breakup and/or debris bed formation and cooling in 2D and 3D geometries. A benchmark for the DEFOR-A experiment of KTH was performed. Important progress was reached for several tasks and aspects and important insights are given, enabling to focus the

  7. Empirical closures for particulate debris bed spreading induced by gas–liquid flow

    Energy Technology Data Exchange (ETDEWEB)

    Basso, S., E-mail: simoneb@kth.se; Konovalenko, A.; Kudinov, P.

    2016-02-15

    Highlights: • Experimental study of the debris bed self-leveling phenomenon. • A scaling approach and a non-dimensional model to describe particle flow rate are proposed. • The model is validated against experiments with particles of different properties and at different gas injection conditions. - Abstract: Efficient removal of decay heat from the nuclear reactor core debris is paramount for termination of severe accident progression. One of the strategies is based on melt fragmentation, quenching and cooling in a deep pool of water under the reactor vessel. Geometrical configuration of the debris bed is among the important factors which determine possibility of removing the decay heat from the debris bed by natural circulation of the coolant. For instance, a tall mound-shape debris bed can be non-coolable, while the same debris can be coolable if spread uniformly. Decay heat generates a significant amount of thermal energy which goes to production of steam inside the debris bed. Two-phase flow escaping through the top layer of the bed becomes a source of mechanical energy which can move the particulate debris along the slope of the bed. The motion of the debris will lead to flattening of the bed. Such process is often called “self-leveling” phenomenon. Spreading of the debris bed by the self-leveling process can take significant time, depending on the initial debris bed configuration and other parameters. There is a competition between the time scales for reaching (i) a coolable configuration of the bed, and (ii) onset of dryout and re-melting of the debris. In the previous work we have demonstrated that the rate of particulate debris spreading is determined by local gas velocity and local slope angle of the bed. In this work we develop a scaling approach and a closure for prediction of debris spreading rate based on generalization of available experimental data. We demonstrate that introduced scaling criteria are universal for particles of different

  8. Numerical simulation for debris bed behavior in sodium cooled fast reactor

    International Nuclear Information System (INIS)

    Tagami, Hirotaka; Tobita, Yoshiharu

    2014-01-01

    For safety analysis of SFR, it is necessary to evaluate behavior along with coolability of debris bed in lower plenum which is formed in severe accident. In order to analyze debris behavior, model for dense sediment particles behavior was proposed and installed in SFR safety analysis code SIMMER. SIMMER code could adequately reproduce experimental results simulating the self-leveling phenomena with appropriate model parameters for bed stiffness. In reactor condition, the self-leveling experiment for prototypical debris bed has not been performed. Additionally, the prototypical debris bed consists of non-spherical particles and it is difficult to quantify model parameters. This situation brings sensitivity analysis to investigate effect of model parameters on the self-leveling phenomena of prototypical debris bed in present paper. As initial condition for sensitivity analysis, simple mound-like debris bed in sodium-filled lower plenum in reactor vessel is considered. The bed consists of the mixture of fuel debris of 3,300 kg and steel debris of 1,570 kg. Decay heat is given to this fuel debris. The model parameter is chosen as sensitivity parameter. Sensitivity analysis shows that the model parameters can effect on intensity of self-leveling phenomena and eventual flatness of bed. In all analyses, however, coolant and sodium vapor break the debris bed at mainly center part of bed and the debris is relocated to outside of bed. Through this process, the initial debris bed is almost planarized before re-melting of debris. This result shows that the model parameters affect the self-leveling phenomena, but its effect in the safety analysis of SFRs is limited. (author)

  9. Debris disc constraints on planetesimal formation

    Science.gov (United States)

    Krivov, Alexander V.; Ide, Aljoscha; Löhne, Torsten; Johansen, Anders; Blum, Jürgen

    2018-02-01

    Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical `slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentration models - provided the objects are loosely bound `pebble piles' as these models also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a `disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ˜1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.

  10. On the influence of water subcooling and melt jet parameters on debris formation

    Energy Technology Data Exchange (ETDEWEB)

    Manickam, Louis, E-mail: louis@safety.sci.kth.se; Kudinov, Pavel; Ma, Weimin; Bechta, Sevostian; Grishchenko, Dmitry

    2016-12-01

    Highlights: • Melt and water configuration effects on debris formation is studied experimentally. • Melt superheat and water subcooling are most influential compared to jet size. • Melt-water configuration and material properties influence particle fracture rate. • Results are compared with large scale experiments to study effect of spatial scales. - Abstract: Breakup of melt jet and formation of a porous debris bed at the base-mat of a flooded reactor cavity is expected during the late stages of a severe accident in light water reactors. Debris bed coolability is determined by the bed properties including particle size, morphology, bed height and shape as well as decay heat. Therefore understanding of the debris formation phenomena is important for assessment of debris bed coolability. A series of experiments was conducted in MISTEE-Jet facility by discharging binary-oxide mixtures of WO{sub 3}–Bi{sub 2}O{sub 3} and WO{sub 3}–ZrO{sub 2} into water in order to investigate properties of resulting debris. The effect of water subcooling, nozzle diameter and melt superheat was addressed in the tests. Experimental results reveal significant influence of water subcooling and melt superheat on debris size and morphology. Significant differences in size and morphology of the debris at different melt release conditions is attributed to the competition between hydrodynamic fragmentation of liquid melt and thermal fracture of the solidifying melt droplets. The particle fracture rate increases with increased subcooling. Further the results are compared with the data from larger scale experiments to discern the effects of spatial scales. The present work provides data that can be useful for validation of the codes used for the prediction of debris formation phenomena.

  11. Models for dryout in debris beds. Review and application to the analysis of PAHR

    International Nuclear Information System (INIS)

    Yamakoshi, Yoshinori

    2000-03-01

    There are many models for dryout in debiris beds and various conditions under which these models are applicable. For a reliable analysis of post-accident heat removal (PAHR), it is important that characteristics and applicability of each model should be made clear. In this report, formulation of the models for dryout and applicability of them are studied through comparing with experimental data. A new model for dryout prediction is also discussed here. It is difficult to predict the dryout power especially for a relatively shallow bed using a conventional model for channeled beds. The new model, which is based on the one-dimensional model derived by Lipinski, has permeability of channels in the governing equation, and enables us to predict the dryout power for relatively shallow beds. The following conclusions are derived from comparing the predicted dryout power with experimental data. The model for series heat removal is applicable to a packed bed while the DEBRIS-MD underestimates the dryout power for it. Either the original model assuming channel formation on the top of the bed or the modified model is applicable to a relatively deep bed with channels. For a relatively shallow bed with channels, the dryout power predicted by the modified model agrees with the experimental data in comparison with other models. (author)

  12. Coolability of oxidized particulate debris bed accumulated in horizontal narrow gaps

    International Nuclear Information System (INIS)

    Arai, Y.; Sugiyama, K.; Narabayashi, T.

    2007-01-01

    When LOCA occurs in a nuclear reactor system, the coolability of the core would be kept as reported at a series of presentations in ICONE14. Therefore the probability of the core meltdown is negligible small. However, from the view point of defense in depth, it is necessary to be sure that the coolability of the bottom of reactor pressure vessel (RPV) is maintained even if a part of the core should melt and a substantial amount of debris should be deposited on the lower plenum. We carried out an experimental study in order to observe the coolability of particulate core-metal debris bed with 12 mm thickness accompanied with rapid heat generation because of oxidization, which was reported at ICONE14. The coolability was assured by a small amount of coolant supply because of high capillary force of oxidized fine particulate debris produced. In the present study, we examined the coolability of particulate debris bed deposited in narrower gap of 1 mm or 5 mm that coolant supply is hard. The particulate debris beds were piled up on the stainless steel sheet with 0.1 mm thickness, which was used to measure the bottom temperatures of particulate debris bed by using a thermo-video camera. We set up a heat supply section with heat input of 2.1 kW, which simulates the hard debris bed deposited on the particulate debris bed as reported for the TMI-2 accident. We measured the temperatures of the bottom surface of the heat supply section and the heat fluxes released into debris bed as well as the temperatures at the bottom of debris bed on the stainless steel sheet. It is found that when only the upper surface of particulate debris bed is in the film boiling, capillary force causes coolant supply to the particulate debris bed. Therefore, in the condition of thicker gap with small particulate debris, coolability of debris bed is improved. We find out that smaller particulate debris is moved by vapor movement. As a result, the area that high capillary force is caused because of

  13. Experimental investigation on single-phase pressure losses in nuclear debris beds: Identification of flow regimes and effective diameter

    Energy Technology Data Exchange (ETDEWEB)

    Clavier, R., E-mail: remi.clavier@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) – PSN-RES/SEREX/LE2M, Cadarache bât. 327, 13115 St Paul-lez-Durance (France); Chikhi, N., E-mail: nourdine.chikhi@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) – PSN-RES/SEREX/LE2M, Cadarache bât. 327, 13115 St Paul-lez-Durance (France); Fichot, F. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) – PSN-RES/SAG/LEPC, Cadarache bât. 700, 13115 St Paul-lez-Durance (France); Quintard, M. [Université de Toulouse – INPT – UPS – Institut de Mécanique des Fluides de Toulouse (IMFT), Allée Camille Soula, F-31400 Toulouse (France); CNRS – IMFT, F-31400 Toulouse (France)

    2015-10-15

    Highlights: • Single-phase pressure drops versus flow rates in particle beds are measured. • Conditions are representative of the reflooding of a nuclear fuel debris bed. • Darcy, weak inertial, strong inertial and weak turbulent regimes are observed. • A Darcy–Forchheimer law is found to be a good approximation in this domain. • A predictive correlation is derived from new experimental data. - Abstract: During a severe nuclear power plant accident, the degradation of the reactor core can lead to the formation of debris beds. The main accident management procedure consists in injecting water inside the reactor vessel. Nevertheless, large uncertainties remain regarding the coolability of such debris beds. Motivated by the reduction of these uncertainties, experiments have been conducted on the CALIDE facility in order to investigate single-phase pressure losses in representative debris beds. In this paper, these results are presented and analyzed in order to identify a simple single-phase flow pressure loss correlation for debris-bed-like particle beds in reflooding conditions, which cover Darcean to Weakly Turbulent flow regimes. The first part of this work is dedicated to study macro-scale pressure losses generated by debris-bed-like particle beds, i.e., high sphericity (>80%) particle beds with relatively small size dispersion (from 1 mm to 10 mm). A Darcy–Forchheimer law, involving the sum of a linear term and a quadratic deviation, with respect to filtration velocity, has been found to be relevant to describe this behavior in Darcy, Strong Inertial and Weak Turbulent regimes. It has also been observed that, in a restricted domain (Re = 15 to Re = 30) between Darcy and Weak Inertial regimes, deviation is better described by a cubic term, which corresponds to the so-called Weak Inertial regime. The second part of this work aims at identifying expressions for coefficients of linear and quadratic terms in Darcy–Forchheimer law, in order to obtain a

  14. Quench cooling of superheated debris beds in containment during LWR core meltdown accidents

    International Nuclear Information System (INIS)

    Ginsberg, T.; Chen, J.C.

    1984-01-01

    Light water reactor core meltdown accident sequence studies suggest that superheated debris beds may settle on the concrete floor beneath the reactor vessel. A model for the heat transfer processes during quench (removal of stored energy from initial temperature to saturation temperature) of superheated debris beds cooled by an overlying pool of water has been presented in a prior paper. This paper discusses the coolability of decay-heated debris beds from the standpoint of their transient quench characteristics. It is shown that even though a debris bed configuration may be coolable from the point of view of steady-state decay heat removal, the quench behavior from an initially elevated temperature may lead to bed melting prior to quench of the debris

  15. Dryout heat flux and flooding phenomena in debris beds consisting of homogeneous diameter particles

    International Nuclear Information System (INIS)

    Maruyama, Yu; Abe, Yutaka; Yamano, Norihiro; Soda, Kunihisa

    1988-08-01

    Since the TMI-2 accident, which occurred in 1979, necessity of understanding phenomena associated with a severe accident have been recognized and researches have been conducted in many countries. During a severe accident of a light water reactor, a debris bed consisting of the degraded core materials would be formed. Because the debris bed continues to release decay heat, the debris bed would remelt when the coolable geometry is not maintained. Thus the degraded core coolability experiments to investigate the influence of the debris particle diameter and coolant flow conditions on the coolability of the debris bed and the flooding experiments to investigate the dependence of flooding phenomena on the configuration of the debris bed have been conducted in JAERI. From the degraded core coolability experiments, the following conclusions were derived; the coolability of debris beds would be improved by coolant supply into the beds, Lipinski's 1-dimensional model shows good agreement with the measured dryout heat flux for the beds under stagnant and forced flow conditions from the bottom of the beds, and the analytical model used for the case that coolant is fed by natural circulation through the downcomer reproduces the experimental results. And the following conclusions were given from the flooding experiments ; no dependence between bed height and the flooding constant exists for the beds lower than the critical bed height, flooding phenomena of the stratified beds would be dominated by the layer consisting of smaller particles, and the predicted dryout heat flux by the analytical model based on the flooding theory gives underestimation under stagnant condition. (author)

  16. Experimental results on the coolability of a debris bed with multidimensional cooling effects

    International Nuclear Information System (INIS)

    Rashid, M.; Kulenovic, R.; Laurien, E.; Nayak, A.K.

    2011-01-01

    Research highlights: ► Performing of dryout experiments with a polydispersed bed for top- and bottom-flooding. ► Study of influence of different down comer configurations on the coolability of debris bed. ► Measurement of temperature profiles, pressure drops and determination of dryout heat flux. ► Observation of noticeable increase in coolability of debris bed with the use of down comer is observed. - Abstract: Within the reactor safety research, the removal of decay heat from a debris bed (formed from corium and residual water) is of great importance. In order to investigate experimentally the long term coolability of debris beds, the scaled test facility “DEBRIS” (Fig. 1) has been built at IKE. A large number of experiments had been carried out to investigate the coolability limits for different bed configurations (). Analyses based on one-dimensional configurations underestimate the coolability in realistic multidimensional configurations, where lateral water access and water inflow via bottom regions are favoured. Following the experiments with top- and bottom-flooding flow conditions this paper presents experimental results of boiling and dryout tests at different system pressures based on top- and bottom-flooding via a down comer configuration. A down comer with an internal diameter of 10 mm has been installed at the centre of the debris bed. The debris bed is built up in a cylindrical crucible with an inner diameter of 125 mm. The bed of height 640 mm is composed of polydispersed particles with particle diameters 2, 3 and 6 mm. Since the long term coolability of such particle bed is limited by the availability of coolant inside the bed and not by heat transfer limitations from the particles to the coolant, the bottom inflow of water improves the coolability of the debris bed and an increase of the dryout heat flux can be observed. With increasing system pressure, the coolability limits are enhanced (increased dryout heat flux).

  17. Cooling of an internal-heated debris bed with fine particles

    International Nuclear Information System (INIS)

    Yang, Z.L.; Sehgal, B.R.

    2001-01-01

    In this paper, an analytical model on dryout heat flux of ex-vessel debris beds with fines particles under top flooding conditions has been developed. The parametric study is performed on the effect of the stratification of the debris beds on the dryout heat flux. The calculated results show that the stratification configuration of the debris beds with smaller particles and lower porosity layer resting on the top of another layer of the beds has profound effect on the dryout heat flux for the debris beds both with and without a downcomer. The enhancement of the dryout heat flux by the downcomer is significant. The efficiency of the single downcomer on the enhancement of the dryout heat flux is also analyzed. This, in general, agrees well with experimental data. The model is also employed to perform the assessment on the coolability of the ex-vessel debris bed under representative accidental conditions. One conservative case is chosen, and it is found that the downcomer could be efficient measure to cool the debris bed and hence terminate the severe accident. (authors)

  18. Transient core-debris bed heat-removal experiments and analysis

    International Nuclear Information System (INIS)

    Ginsberg, T.; Klein, J.; Klages, J.; Schwarz, C.E.; Chen, J.C.

    1982-08-01

    An experimental investigation is reported of the thermal interaction between superheated core debris and water during postulated light-water reactor degraded core accidents. Data are presented for the heat transfer characteristics of packed beds of 3 mm spheres which are cooled by overlying pools of water. Results of transient bed temperature and steam flow rate measurements are presented for bed heights in the range 218 mm-433 mm and initial particle bed temperatures between 530K and 972K. Results display a two-part sequential quench process. Initial frontal cooling leaves pockets or channels of unquenched spheres. Data suggest that heat transfer process is limited by a mechanism of countercurrent two-phase flow. An analytical model which combines a bed energy equation with either a quasisteady version of the Lipinski debris bed model or a critical heat flux model reasonably well predicts the characteristic features of the bed quench process. Implications with respect to reactor safety are discussed

  19. Analysis of dryout behaviour in laterally non-homogeneous debris beds using the MEWA-2D code

    International Nuclear Information System (INIS)

    Rahman, Saidur; Buerger, Manfred; Buck, Michael; Pohlner, Georg; Kulenovic, Rudi; Nayak, Arun Kumar; Sehgal, Bal Raj

    2009-01-01

    . Both cases appear to be important for getting a realistic perspective on coolability of debris beds under reactor conditions. While the latter mechanism of the loop formation appears to be more important for the global behaviour, the capillary mechanism can be considered as especially important for improved cooling of the low porosity regions. Further elaboration of the strength of effects under variation of conditions is to be encouraged based on the present analysis. (author)

  20. Internal structure of an ex-vessel corium debris bed during severe accidents of LWRs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eunho; Park, Jin Ho; Moriyama, Kiyofumi; Park, Hyun Sun [POSTECH, Daejeon (Korea, Republic of)

    2015-10-15

    In the aspect of the coolability assessment the configuration of the debris bed, including internal and external characteristics, has significant importance as boundary conditions for simulations, however, relatively little investigation of the sedimentation process. For the development of a debris bed, recently there have been several studies that focused on thermal characteristics of corium particles. Yakush et al. performed simulation studies and showed that two phase natural convection affects the particle settling trajectory and changes the final arrival location of particles to result more flattened bed. Those simulation results have been supported by the experimental studies of Kim et al. using simulant particles and air bubble injection. For the internal structure of a debris bed, there have been several simulation and experimental studies, which investigated the effect of internal structure on debris bed coolability. Magallon has reported the particle size distribution at three elevations of the debris bed of FARO L-31 case, where the mean particle size was bigger for the lower elevation. However, there is a lack of detailed information on the characteristics of the debris bed, including the local structure and porosity. In this study, we investigated the internal structure of the debris bed using a mixture of stainless steel particles and air bubble injection. Local particle sedimentation quantity, particle size distribution change in radial direction and axial direction, and bed porosity was measured to investigate a relationship between the internal structure and the accident condition. An experimental investigation was carried out for the internal structure of ex-vessel corium debris bed in the flooded cavity during sever accident. Moderate corium discharge in high flooding level was assumed for full fragmentation of melt jet. The test particle mixture was prepared by following an empirical correlation, which reflects the particle size distribution of

  1. Internal structure of an ex-vessel corium debris bed during severe accidents of LWRs

    International Nuclear Information System (INIS)

    Kim, Eunho; Park, Jin Ho; Moriyama, Kiyofumi; Park, Hyun Sun

    2015-01-01

    In the aspect of the coolability assessment the configuration of the debris bed, including internal and external characteristics, has significant importance as boundary conditions for simulations, however, relatively little investigation of the sedimentation process. For the development of a debris bed, recently there have been several studies that focused on thermal characteristics of corium particles. Yakush et al. performed simulation studies and showed that two phase natural convection affects the particle settling trajectory and changes the final arrival location of particles to result more flattened bed. Those simulation results have been supported by the experimental studies of Kim et al. using simulant particles and air bubble injection. For the internal structure of a debris bed, there have been several simulation and experimental studies, which investigated the effect of internal structure on debris bed coolability. Magallon has reported the particle size distribution at three elevations of the debris bed of FARO L-31 case, where the mean particle size was bigger for the lower elevation. However, there is a lack of detailed information on the characteristics of the debris bed, including the local structure and porosity. In this study, we investigated the internal structure of the debris bed using a mixture of stainless steel particles and air bubble injection. Local particle sedimentation quantity, particle size distribution change in radial direction and axial direction, and bed porosity was measured to investigate a relationship between the internal structure and the accident condition. An experimental investigation was carried out for the internal structure of ex-vessel corium debris bed in the flooded cavity during sever accident. Moderate corium discharge in high flooding level was assumed for full fragmentation of melt jet. The test particle mixture was prepared by following an empirical correlation, which reflects the particle size distribution of

  2. Application of debris-bed dryout data to CONACS-1 modeling

    International Nuclear Information System (INIS)

    Gabor, J.D.; Cassulo, J.C.; Pedersen, D.R.

    1982-01-01

    CONACS-1 (the first version of the DOE Containment Analysis Code System) which is currently under development requires extension of existing debris-bed dryout data to the wide range of conditions possible in an accident sequence. While there has been much effort on modeling of debris-bed dryout from first principles, there is no definitive model for beds of irregularly shaped particles of wide size distribution and for beds of varying heights. Existing debris-bed heat-transfer data with real materials are for the most part limited to dryout as a function of bed depth for adiabatic conditions of atmospheric pressure. These data must be extrapolated with the use of appropriate theoretical models based on experimentation with simulant materials to the ocnditions under consideration in the containment analysis. The data base selected for CONACS-1 is from measurements of dryout for beds of 100 to 1000 μm UO 2 with the sodium phase Joule heated. This particle size range which is typical for debris from fuel-coolant interactions is the most reasonable to use

  3. Fundamental study on dynamic behaviors of fuel debris bed. Research report in 2007 (Joint research)

    International Nuclear Information System (INIS)

    Morita, Koji; Fukuda, Kenji; Matsumoto, Tatsuya; Tobita, Yoshiharu; Suzuki, Tohru; Yamano, Hidemasa

    2009-05-01

    It is important to make a reasonable evaluation of coolability of debris bed with decay heat source in assessing post accident heat removal of a liquid metal cooled fast reactor. In general, the coolability of fuel debris depends on coolant convection, boiling and debris bed movement. In the present study, to understand fundamental characteristics of debris movement, self-leveling behavior caused by the coolant boiling was investigated experimentally using simulant materials. The present experiments employed depressurization boiling of water to simulate void distribution in a debris bed, which consists of solid particles of alumina. A rough estimation model of self-leveling occurrence was proposed and compared with the experimental results. Its extrapolation to reactor accident conditions was also discussed. In addition, solid-liquid flow experiments, which are relevant to debris bed movement behaviors, were analyzed to verify the validity of multiphase flow models employed in a safety analysis code. In the present verification study, basic validity of the code was demonstrated by analyzing experiments of water-column sloshing with solid particles. (author)

  4. Debris and pool formation/heat transfer in FARO-LWR: experiments and analyses

    International Nuclear Information System (INIS)

    Magallon, D.; Annunziato, A.; Corradini, M.

    1999-01-01

    The FARO-LWR experiments examine the debris and pool formation from a pour of core melt materials (UO 2 /ZrO 2 and UO 2 /ZrO 2 /Zr) into a pool of water at prototypic accident conditions. The experiments give unique data on the debris bed initial conditions, morphology and heat transfer after the core melt has slump and (partly) quenched into the water of the lower head. Quantities of up to 170 kg of corium melt are poured by gravity into water of depth between 1 and 2 m through a nozzle of diameter 0.1 m at different system pressures. The debris is collected in a flat bottom catcher of diameter 0.66 m. It reaches heights up to 0.2 m depending on the melt quantity. In general, the melt reaches the bottom only partially fragmented. The debris which forms consists of a conglomerate ('cake') in contact with the collecting structure and overlaying fragments (loose debris). The mean particle size of the loose debris is in the range 3.5 - 4.8 mm. The upper surface of the debris is flat. A gap is present between the cake and the bottom plate. The paper reviews the debris formation and heat transfer to the bottom steel structure from these tests and describes the development of a model to predict the debris and pool formation process. Sensitivity analyses have been performed by the COMETA code to study the behaviour of the ratio between the cake mass and the total mass. (authors)

  5. Experimental investigation of multidimensional cooling effects on the coolability of a debris bed

    International Nuclear Information System (INIS)

    Rashidi, M.; Kulenovici, R.; Laurieni, E.

    2011-01-01

    During a severe accident in a light water reactor, the core can melt and be relocated to the lower plenum of the reactor pressure vessel. There it can form a particulate debris bed due to the possible presence of water. Within the reactor safety research, the removal of decay heat from a debris bed (formed from corium and residual water) is of great importance. In order to investigate experimentally the long-term coolability of debris beds, the down-scaled non nuclear test facility DEBRIS has been established at IKE. The major objectives of the experimental investigations at this test facility are the determination of local pressure drops for steady state boiling to check friction laws, the determination of dryout heat fluxes under various conditions for validation of numerical models, and the analysis of quenching processes of dry hot debris beds. A large number of 1D-experiments were carried out to investigate the coolability limits for different bed configurations at various thermohydraulic conditions, and to validate numerical models which can be used in reactor safety studies. Analyses based on one-dimensional configurations underestimate the coolability in realistic multidimensional configurations, where lateral water access and water inflow via bottom regions are favored. This paper presents 2D experimental results, based on various kinds of water inflow conditions into the bed, boiling and dryout tests with different bed configurations and different system pressures. Preliminary results show that the system pressure has no significant effect on the fundamental shape of the pressure gradient inside the bed, whereas with increasing system pressure the coolability limits are increased

  6. An experimental simulation study of debris quenching in a radially stratified porous bed

    International Nuclear Information System (INIS)

    Sehgal, B.R.; Nayak, A.K.; Stepanyan, A.

    2004-01-01

    During a severe accident condition in a nuclear power plant, the core melt can fail the reactor vessel and relocate into the containment basement. In some accident management schemes, the vessel cavity is flooded with water. For these a particulate debris bed is likely to form on the cavity floor due to melt break-up in water. . In this situation, the coolability of debris bed on the containment floor is a crucial issue. This is because the debris bed still generates the decay heat and if it is uncoolable, it can eventually remelt and react with concrete basement generating a lot of noncondensable gases and pressurising the containment. Hence, it is important to cool the debris bed as an accident management programme. The main parameters affecting the coolability of the debris bed are its porosity which is a function of the size and shape of the particles which constitute the debris bed, the operating condition such as water flooding from the top or bottom of debris bed, water temperature and non-condensable gas generated during bed-concrete interactions. It is found from previous studies that the debris bed has a non-uniform particle distribution or a porosity stratification. This can happen both in radial and axial plane. For example, the bed can have a lower porosity at the centre and higher porosity at the periphery. It is of interest to investigate the quenching phenomena in such configurations so as to find an effective means of quenching the heat generating bed. While most of the previous investigations mainly concentrate on quenching of a homogenous or axially stratified particulate bed with volumetric heat generation, there are almost no studies on the above phenomena in a radially stratified porous bed. So the objective of this paper is to investigate the quenching phenomena in a radially stratified bed. To simulate the phenomena, we conducted experiments in an experimental facility named as POMECO (POrous MEdia COolability). The facility has a square

  7. Modes of heat removal from a heat-generating debris bed

    International Nuclear Information System (INIS)

    Squarer, D.; Hochreiter, L.E.; Piecznski, A.T.

    1984-01-01

    In the worst hypothetical accident in a light water reactor, when all protection systems fail, the core could be converted into a deep particulate bed either in-vessel or ex-vessel. The containment of such an accident depends on the coolability of a heat-generating debris bed. Some recent experimental and analytical studies that are concerned with heat removal from such a particulate bed are reviewed. Studies have indicated that bed dryout flux and, therefore, the heat removal rate from the particulate bed increases with the particle diameter (i.e., the permeability) for pool boiling conditions and can exceed the critical heat flux of a flat plate. Bed dryout in a large particle bed (i.e., a few millimetres) was found to be closely related to the ''flooding'' limit of the bed. Dryout under forced flow conditions was found to be affected by both forced and natural convection for mass flow rate smaller than m /SUB cr/ , whereas above this mass flow rate, bed dryout is proportional to the mass flow rate. Recent analyses were found to be in agreement with experimental data; however, additional research is needed to assess factors not accounted for in previous studies (e.g., effect of pressure, multidimensionality, stratification, etc.). Based on the expected pressure and particle sizes in a postulated severe accident sequence, a debris bed should be coolable, given a sufficient water supply

  8. Experimental and theoretical study of large scale debris bed reflood in the PEARL facility

    Energy Technology Data Exchange (ETDEWEB)

    Chikhi, Nourdine, E-mail: nourdine.chikhi@irsn.fr; Fichot, F.

    2017-02-15

    Highlights: • Five reflooding tests have been carried out with an experimental bed, 500 mm in height and 500 mm in diameter, made of 4 mm stainless steel balls. • For the first time, such a large bed was heated practically homogenously. • The quench front velocity was determined according to thermocouple measurements inside the bed. • An analytical model, assuming a quasi-steady progression of the quench front, allows to predict the conversion ratio in most cases. • It appears that the efficiency of cooling can be increased only up to a certain limit when increasing the inlet water flow rate. - Abstract: During a severe accident in a nuclear power plant, the degradation of fuel rods and melting of materials lead to the accumulation of core materials, which are commonly, called “debris beds”. To stop core degradation and avoid the reactor vessel rupture, the main accident management procedure consists in injecting water. In the case of debris bed, the reflooding models used for Loss of Coolant Accident are not applicable. The IRSN has launched an experimental program on debris bed reflooding to develop new models and to validate severe accident codes. The PEARL facility has been designed to perform, for the first time, the reflooding of large scale debris bed (Ø540 mm, h = 500 mm and 500 kg of steel debris) in a pressurized containment. The bed is heated by means of an induction system. A specific instrumentation has been developed to measure the debris bed temperature, pressure drop inside the bed and the steam flow rate during the reflooding. In this paper, the results of the first integral reflooding tests performed in the PEARL facility at atmospheric pressure up to 700 °C are presented. Focus is made on the quench front propagation and on the steam flow rate during reflooding. The effect of water injection flow rate, debris initial temperature and residual power are also discussed. Finally, an analytical model providing the steam flow rate and

  9. Experimental investigation of coolability behaviour of irregularly shaped particulate debris bed

    International Nuclear Information System (INIS)

    Kulkarni, P.P.; Rashid, M.; Kulenovic, R.; Nayak, A.K.

    2010-01-01

    In case of a severe nuclear reactor accident, the core can melt and form a particulate debris bed in the lower plenum of the reactor pressure vessel (RPV). Due to the decay heat, the particle bed, if not cooled properly, can cause failure of the RPV. In order to avoid further propagation of the accident, complete coolability of the debris bed is necessary. For that, understanding of various phenomena taking place during the quenching is important. In the frame of the reactor safety research, fundamental experiments on the coolability of debris beds are carried out at IKE with the test facility 'DEBRIS'. In the present paper, the boiling and dry-out experimental results on a particle bed with irregularly shaped particles mixed with stainless steel balls have been reported. The pressure drops and dry-out heat fluxes of the irregular-particle bed are very similar to those for the single-sized 3 mm spheres bed, despite the fact that the irregular-particle bed is composed of particles with equivalent diameters ranging from 2 to 10 mm. Under top-flooding conditions, the pressure gradients are all smaller than the hydrostatic pressure gradient of water, indicating an important role of the counter-current interfacial drag force. For bottom-flooding with a liquid inflow velocity higher than about 2.7 mm/s, the pressure gradient generally increases consistently with the vapour velocity and the fluid-particle drag becomes important. The system pressures (1 and 3 bar) have negligible effects on qualitative behaviour of the pressure gradients. The coolability of debris beds is mainly limited by the counter-current flooding limit (CCFL) even under bottom-flooding conditions with low flow rates. The system pressure and the flow rate are found to have a distinct effect on the dry-out heat flux. Different classical models have been used to predict the pressure drop characteristics and the dry-out heat flux (DHF). Comparisons are made among the models and experimental results for

  10. Review of the Technical Status on the Debris Bed Cooling Model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eui Kwang; Cho, Chung Ho; Lee, Yong Bum

    2007-09-15

    Preliminary safety analyses of the KALIMER-600 design have shown that the design has inherent safety characteristics and is capable of accommodating double-fault initiators such as ATWS events without coolant boiling or fuel melting. However, for the future design of sodium cooled fast reactor, the evaluation of the safety performance and the determination of containment requirements may be worth due consideration of triple-fault accident sequences of extremely low probability of occurrence that leads to core melting. For any postulated accident sequence which leads to core melting, in-vessel retention of the core debris will be required as a design requirement for the future design of sodium cooled fast reactor. Also, proof of the capacity of the debris bed cooling is an essential condition to solve the problem of in-vessel retention of the core debris. In this study, review of the technical status on the debris bed cooling model was carried out for in-vessel retention of the core debris0.

  11. Review of the Technical Status on the Debris Bed Cooling Model

    International Nuclear Information System (INIS)

    Kim, Eui Kwang; Cho, Chung Ho; Lee, Yong Bum

    2007-09-01

    Preliminary safety analyses of the KALIMER-600 design have shown that the design has inherent safety characteristics and is capable of accommodating double-fault initiators such as ATWS events without coolant boiling or fuel melting. However, for the future design of sodium cooled fast reactor, the evaluation of the safety performance and the determination of containment requirements may be worth due consideration of triple-fault accident sequences of extremely low probability of occurrence that leads to core melting. For any postulated accident sequence which leads to core melting, in-vessel retention of the core debris will be required as a design requirement for the future design of sodium cooled fast reactor. Also, proof of the capacity of the debris bed cooling is an essential condition to solve the problem of in-vessel retention of the core debris. In this study, review of the technical status on the debris bed cooling model was carried out for in-vessel retention of the core debris

  12. Enhanced stability of steep channel beds to mass failure and debris flow initiation

    Science.gov (United States)

    Prancevic, J.; Lamb, M. P.; Ayoub, F.; Venditti, J. G.

    2015-12-01

    Debris flows dominate bedrock erosion and sediment transport in very steep mountain channels, and are often initiated from failure of channel-bed alluvium during storms. While several theoretical models exist to predict mass failures, few have been tested because observations of in-channel bed failures are extremely limited. To fill this gap in our understanding, we performed laboratory flume experiments to identify the conditions necessary to initiate bed failures in non-cohesive sediment of different sizes (D = 0.7 mm to 15 mm) on steep channel-bed slopes (S = 0.45 to 0.93) and in the presence of water flow. In beds composed of sand, failures occurred under sub-saturated conditions on steep bed slopes (S > 0.5) and under super-saturated conditions at lower slopes. In beds of gravel, however, failures occurred only under super-saturated conditions at all tested slopes, even those approaching the dry angle of repose. Consistent with theoretical models, mass failures under super-saturated conditions initiated along a failure plane approximately one grain-diameter below the bed surface, whereas the failure plane was located near the base of the bed under sub-saturated conditions. However, all experimental beds were more stable than predicted by 1-D infinite-slope stability models. In partially saturated sand, enhanced stability appears to result from suction stress. Enhanced stability in gravel may result from turbulent energy losses in pores or increased granular friction for failures that are shallow with respect to grain size. These grain-size dependent effects are not currently included in stability models for non-cohesive sediment, and they may help to explain better the timing and location of debris flow occurrence.

  13. Development and application of surrogate model for assessment of ex-vessel debris bed dryout probability - 15157

    International Nuclear Information System (INIS)

    Yakush, S.E.; Lubchenko, N.T.; Kudinov, P.

    2015-01-01

    In this work we consider a water-cooled power reactor severe accident scenario with pressure vessel failure and subsequent release of molten corium. A surrogate model for prediction of dryout heat flux for ex-vessels debris beds of different shapes is developed. Functional form of dryout heat flux dependence on problem parameters is developed by the analysis of coolability problem in non-dimensional variables. It is shown that for a flat debris bed the dryout heat flux can be represented in terms of three 1-dimensional functions for which approximating formulas are found. For two-dimensional debris beds (cylindrical, conical, Gaussian heap, mound-shaped), an additional function taking into account the bed shape geometry is obtained from numerical simulations using DECOSIM code as a full model. With the surrogate model in hand, risk analysis of debris bed coolability is carried out by Monte Carlo sampling of the input parameters within selected ranges, with assumed distribution functions

  14. Experimental Investigation of the Effect of Particle Shape on Frictional Pressure drop in Particulate Debris Bed

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin Ho; Kim, Eun Ho; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of)

    2014-10-15

    To ensure the long-term cooling of corium in the reactor cavity, it is important to ensure the coolant ingression into the internally heat generated corium debris bed which is governed by pressure drop in porous media. For this reason, it is necessary to understand pressure drop mechanisms in porous bed to verify the feasibility of water penetration into particulate debris bed. According to the previous investigations on molten fuel-coolant interaction (FCI) experiments, it was found that quenched particulate debris bed was composed of irregular shape particles. Therefore, empirical or semiempirical models based on the Ergun equation (Ergun, 1952) for single-phase flow in porous media composed of single sized spherical particle were developed to consider the effect of particle shape on frictional pressure drop by means of adding a shape factor or modifying the Ergun constants etc. (Leva, 1959, Handley and Heggs, 1968, Macdonald, 1979, Foumeny et al., 1996). An experimental investigate on single-phase frictional pressure drop of water in packed bed was conducted in the transparent cylindrical test section with the inner diameter of 100 mm and the height of 700 mm to study the effect of particle shape on frictional pressure drop in porous media. This paper reports the experimental data for spherical particles with the diameter of 2 mm and 5 mm and cylindrical particles with ED of 2 mm and 5 mm. And also, the experimental data compared with the models to predict frictional pressure drop in particulate bed. The conclusions are summarized as follows. As a result of the experiment to measure frictional pressure drop in particulate bed composed of cylindrical particles the models predict the experimental data well within 22.11 % except the Handley and Heggs model when ED is applied to the models.

  15. Experimental Investigation of the Effect of Particle Shape on Frictional Pressure drop in Particulate Debris Bed

    International Nuclear Information System (INIS)

    Park, Jin Ho; Kim, Eun Ho; Park, Hyun Sun

    2014-01-01

    To ensure the long-term cooling of corium in the reactor cavity, it is important to ensure the coolant ingression into the internally heat generated corium debris bed which is governed by pressure drop in porous media. For this reason, it is necessary to understand pressure drop mechanisms in porous bed to verify the feasibility of water penetration into particulate debris bed. According to the previous investigations on molten fuel-coolant interaction (FCI) experiments, it was found that quenched particulate debris bed was composed of irregular shape particles. Therefore, empirical or semiempirical models based on the Ergun equation (Ergun, 1952) for single-phase flow in porous media composed of single sized spherical particle were developed to consider the effect of particle shape on frictional pressure drop by means of adding a shape factor or modifying the Ergun constants etc. (Leva, 1959, Handley and Heggs, 1968, Macdonald, 1979, Foumeny et al., 1996). An experimental investigate on single-phase frictional pressure drop of water in packed bed was conducted in the transparent cylindrical test section with the inner diameter of 100 mm and the height of 700 mm to study the effect of particle shape on frictional pressure drop in porous media. This paper reports the experimental data for spherical particles with the diameter of 2 mm and 5 mm and cylindrical particles with ED of 2 mm and 5 mm. And also, the experimental data compared with the models to predict frictional pressure drop in particulate bed. The conclusions are summarized as follows. As a result of the experiment to measure frictional pressure drop in particulate bed composed of cylindrical particles the models predict the experimental data well within 22.11 % except the Handley and Heggs model when ED is applied to the models

  16. Numerical simulations on self-leveling behaviors with cylindrical debris bed

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liancheng, E-mail: Liancheng.guo@kit.edu [Institute for Nuclear and Energy Technologies (IKET), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Morita, Koji, E-mail: morita@nucl.kyushu-u.ac.jp [Faculty of Engineering, Kyushu University, 2-3-7, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Tobita, Yoshiharu, E-mail: tobita.yoshiharu@jaea.go.jp [Fast Reactor Safety Technology Development Department, Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki 311-1393 (Japan)

    2017-04-15

    Highlights: • A 3D coupled method was developed by combining DEM with the multi-fluid model of SIMMER-IV code. • The method was validated by performing numerical simulations on a series of experiments with cylindrical particle bed. • Reasonable agreement can demonstrate the applicability of the method in reproducing the self-leveling behavior. • Sensitivity analysis on some model parameters was performed to assess their impacts. - Abstract: The postulated core disruptive accidents (CDAs) are regarded as particular difficulties in the safety analysis of liquid-metal fast reactors (LMFRs). In the CDAs, core debris may settle on the core-support structure and form conic bed mounds. Then debris bed can be levelled by the heat convection and vaporization of surrounding coolant sodium, which is named “self-leveling behavior”. The self-leveling behavior is a crucial issue in the safety analysis, due to its significant effect on the relocation of molten core and heat-removal capability of the debris bed. Considering its complicate multiphase mechanism, a comprehensive computational tool is needed to reasonably simulate transient particle behavior as well as thermal-hydraulic phenomenon of surrounding fluid phases. The SIMMER program is a successful computer code initially developed as an advanced tool for CDA analysis of LMFRs. It is a multi-velocity-field, multiphase, multicomponent, Eulerian, fluid dynamics code coupled with a fuel-pin model and a space- and energy-dependent neutron kinetics model. Until now, the code has been successfully applied in numerical simulations for reproducing key thermal-hydraulic phenomena involved in CDAs as well as performing reactor safety assessment. However, strong interactions between massive solid particles as well as particle characteristics in multiphase flows were not taken into consideration in its fluid-dynamics models. To solve this problem, a new method is developed by combining the discrete element method (DEM

  17. Cooling of particulate debris beds: analysis of the initial D-series experiments

    International Nuclear Information System (INIS)

    Rivard, J.B.

    1978-01-01

    In an effort to provide basic data on the cooling of fast reactor debris, three in-pile experiments employing oxide fuel particulate in liquid sodium were completed in late 1977. Preliminary results from these experiments were reported shortly after their completion at the Third Post-Accident Heat Removal Information Exchange, at Argonne National Laboratory. In these experiments, a distribution of 100 μm to 1000 μm-sized particles of enriched UO 2 was fission-heated to simulate decay-heated debris. In each experiment, the UO 2 particles were contained in a closed, flat-bottomed vessel 012 mm in diameter which was insulated on the diameter and bottom. Sufficient sodium was included to saturate the bed of particles and to provide a volume of bulk sodium above the bed at a controlled temperature. Parameters of interest in the experiments are given

  18. Elementary theory of bed-sediment entrainment by debris flows and avalanches

    Science.gov (United States)

    Iverson, Richard M.

    2012-01-01

    Analyses of mass and momentum exchange between a debris flow or avalanche and an underlying sediment layer aid interpretations and predictions of bed-sediment entrainment rates. A preliminary analysis assesses the behavior of a Coulomb slide block that entrains bed material as it descends a uniform slope. The analysis demonstrates that the block's momentum can grow unstably, even in the presence of limited entrainment efficiency. A more-detailed, depth-integrated continuum analysis of interacting, deformable bodies identifies mechanical controls on entrainment efficiency, and shows that entrainment rates satisfy a jump condition that involves shear-traction and velocity discontinuities at the flow-bed boundary. Explicit predictions of the entrainment rateEresult from making reasonable assumptions about flow velocity profiles and boundary shear tractions. For Coulomb-friction tractions, predicted entrainment rates are sensitive to pore fluid pressures that develop in bed sediment as it is overridden. In the simplest scenario the bed sediment liquefies completely, and the entrainment-rate equation reduces toE = 2μ1gh1 cos θ(1 − λ1)/ , where θ is the slope angle, μ1 is the flow's Coulomb friction coefficient, h1 is its thickness, λ1 is its degree of liquefaction, and is its depth-averaged velocity. For values ofλ1ranging from 0.5 to 0.8, this equation predicts entrainment rates consistent with rates of 0.05 to 0.1 m/s measured in large-scale debris-flow experiments in which wet sediment beds liquefied almost completely. The propensity for bed liquefaction depends on several factors, including sediment porosity, permeability, and thickness, and rates of compression and shear deformation that occur when beds are overridden.

  19. COOLOCE debris bed experiments and simulations investigating the coolability of cylindrical beds with different materials and flow modes

    Energy Technology Data Exchange (ETDEWEB)

    Takasuo, E.; Kinnunen, T.; Holmstroem, S.; Lehtikuusi, T. [VTT Technical Research Centre of Finland (Finland)

    2013-07-15

    The COOLOCE experiments aim at investigating the coolability of debris beds of different geometries, flow modes and materials. A debris bed may be formed of solidified corium as a result of a severe accident in a nuclear power reactor. The COOLOCE-8 test series consisted of experiments with a top-flooded test bed with irregular gravel as the simulant material. The objective was to produce comparison data useful in estimating the effects of different particle materials and the possible effect of the test arrangement on the results. It was found that the dryout heat flux (DHF) measured for the gravel was lower compared to previous experiments with spherical beads, and somewhat lower compared to the early STYX experiments. The difference between the beads and gravel is at least partially explained by the smaller average size of the gravel particles. The COOLOCE-9 test series included scoping experiments examining the effect of subcooling of the water pool in which the debris bed is immersed. The experiments with initially subcooled pool suggest that the subcooling may increase DHF and increase coolability. The aim of the COOLOCE-10 experiments was to investigate the effect of lateral flooding on the DHF a cylindrical test bed. The top of the test cylinder and its sidewall were open to water infiltration. It was found that the DHF is increased compared to a top-flooded cylinder by more than 50%. This suggests that coolability is notably improved. 2D simulations of the top-flooded test beds have been run with the MEWA code. Prior to the simulations, the effective particle diameter for the spherical beads and the irregular gravel was estimated by single-phase pressure loss measurements performed at KTH in Sweden. Parameter variations were done for particle size and porosity used as input in the models. It was found that with the measured effective particle diameter and porosity, the simulation models predict DHF with a relatively good accuracy in the case of spherical

  20. CHARACTERISTICS OF SELF-LEVELING BEHAVIOR OF DEBRIS BEDS IN A SERIES OF EXPERIMENTS

    Directory of Open Access Journals (Sweden)

    SONGBAI CHENG

    2013-06-01

    Full Text Available During a hypothetical core-disruptive accident (CDA in a sodium-cooled fast reactor (SFR, degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of the core material pool. However, coolant boiling may ultimately lead to leveling of the debris bed, which is crucial to the relocation of the molten core and heat-removal capability of the debris bed. To clarify the mechanisms underlying this self-leveling behavior, a large number of experiments were performed within a variety of conditions in recent years, under the constructive collaboration between the Japan Atomic Energy Agency (JAEA and Kyushu University (Japan. The present contribution synthesizes and gives detailed comparative analyses of those experiments. Effects of various experimental parameters that may have potential influence on the leveling process, such as boiling mode, particle size, particle density, particle shape, bubbling rate, water depth and column geometry, were investigated, thus giving a large palette of favorable data for the better understanding of CDAs, and improved verifications of computer models developed in advanced fast reactor safety analysis codes.

  1. Characteristics of Self-Leveling Behavior of Debris Beds in A Series of Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Songbai; Yamano, Hidemasa; Suzuki, Tohru; Tobita, Yoshiharu [Japan Atomic Energy Agency, Ibaraki (Japan); Yuya, Nakamura; Bin, Zhang; Tatsuya, Matsumoto; Koji, Morita [Kyushu Univ., Fukuoka (Japan)

    2013-06-15

    During a hypothetical core-disruptive accident (CDA) in a sodium-cooled fast reactor (SFR), degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of the core material pool. However, coolant boiling may ultimately lead to leveling of the debris bed, which is crucial to the relocation of the molten core and heat-removal capability of the debris bed. To clarify the mechanisms underlying this self-leveling behavior, a large number of experiments were performed within a variety of conditions in recent years, under the constructive collaboration between the Japan Atomic Energy Agency (JAEA) and Kyushu University (Japan). The present contribution synthesizes and gives detailed comparative analyses of those experiments. Effects of various experimental parameters that may have potential influence on the leveling process, such as boiling mode, particle size, particle density, particle shape, bubbling rate, water depth and column geometry, were investigated, thus giving a large palette of favorable data for the better understanding of CDAs, and improved verifications of computer models developed in advanced fast reactor safety analysis codes.

  2. Characteristics of Self-Leveling Behavior of Debris Beds in A Series of Experiments

    International Nuclear Information System (INIS)

    Cheng, Songbai; Yamano, Hidemasa; Suzuki, Tohru; Tobita, Yoshiharu; Yuya, Nakamura; Bin, Zhang; Tatsuya, Matsumoto; Koji, Morita

    2013-01-01

    During a hypothetical core-disruptive accident (CDA) in a sodium-cooled fast reactor (SFR), degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of the core material pool. However, coolant boiling may ultimately lead to leveling of the debris bed, which is crucial to the relocation of the molten core and heat-removal capability of the debris bed. To clarify the mechanisms underlying this self-leveling behavior, a large number of experiments were performed within a variety of conditions in recent years, under the constructive collaboration between the Japan Atomic Energy Agency (JAEA) and Kyushu University (Japan). The present contribution synthesizes and gives detailed comparative analyses of those experiments. Effects of various experimental parameters that may have potential influence on the leveling process, such as boiling mode, particle size, particle density, particle shape, bubbling rate, water depth and column geometry, were investigated, thus giving a large palette of favorable data for the better understanding of CDAs, and improved verifications of computer models developed in advanced fast reactor safety analysis codes

  3. Coolability of a 3D homogeneous debris bed, experimental and numerical investigations

    International Nuclear Information System (INIS)

    Atkhen, K.; Berthoud, G.

    2001-01-01

    Within the framework of nuclear safety analysis, we present here experimental and numerical results in the field of debris bed coolability. Experimental data are provided by the SILFIDE 3D experimental facility in which the debris bed is heated by induction, at Electricite de France (EDF). Numerical computations are obtained with MC3D-REPO which is a 3-phase and 3D code developed by the Commissariat a l'Energie Atomique (CEA). The uniform debris bed consists of 2 and 3,17 mm diameter steel beads contained in a 50 cm x 60 cm x 10 cm vessel. Water is used as a coolant and can be introduced either by the top or the bottom of the bed at a determined temperature. Due to heterogeneous power distribution within the bed, two definitions for the critical heat flux are proposed: the classical mean value and the local flux (much higher). Even in the first case, the measured dryout heat flux is higher than the Lipinsky 1-D flux. Temperature curve analyses show that the dryout phenomenon is very local, therefore one should be careful about the right flux definition to use. As the injected power is being increased stepwise, steady temperature stages above saturation temperature before dryout can be observed. A discussion is proposed. For some very high values of the induction power, some spheres melted together, leading to a bigger non-porous region. Even if the local temperature went over 1300 C, the bed was still coolable and the critical heat flux value was not impacted. Some parametric studies led to the following conclusions: bottom coolant injection leads to a twice time higher critical flux than by top injection, the influence of the height of the water pool above debris bed is negligible, a sub-cooled liquid injection has no influence on the coolability. Fluidization of surface particles is also discussed. The MC3D-REPO model assumes a thermal equilibrium between the three phases, which gives results in agreement with experiments until dryout occurs. (author)

  4. Code development for debris bed coolability problem. Final report for the period 1997-05-01 - 1999-08-14

    International Nuclear Information System (INIS)

    Loboiko, A.I.

    2000-03-01

    The study was devoted to the problem of debris bed coolability arising from severe accident at nuclear power reactor. After reactor core melting occurs and subsequent debris bed is formed in the lower plenum of reactor pressure vessel (RPV) it is important to confine this debris bed inside RPV boundary. One of the possible accident scenarios assumes the interaction between coolant and molten core materials resulting from rapid melt quenching, freezing and fragmentation. Particulated fuel and steel may subsequently settle on available surfaces within the reactor vessel, forming debris porous beds which produce radioactive decay heating. In case of severe core degradation, such heat transfer mechanisms as radiation, conduction and natural single-phase convection may appear to be insufficient and coolant boiling may happen on the surface or inside the bed. Depending on rate of heat generation there may be sufficient debris cool down or its 'dryout' which pose a danger for RPV integrity. The study considers development of 2D numerical code capable to predict coolant saturation as a function of different parameters. Analysis of previous activities on one-dimensional and multi-dimensional models was done. On the basis of the analysis it was concluded that the correct prediction of the debris saturation on dryant power requires two-dimensional numerical simulation considering the processes like two-phase convection, capillary effects, different models of permeability, different models of heat transfer between solid debris and coolant, non-homogeneity of parameters porous medium, heat and mass transfer between debris bed and a highly porous gap along the inner RPV surface. Particular attention was given to consideration of boundary conditions for debris bed. Introduction of the analytical model for dependence of gap properties on heat flux from debris bed allowed to create an algorithm for use in numerical calculations and finally to develop a code which allowed for stable

  5. Idealized debris flow in flume with bed driven by a conveyor belt

    Science.gov (United States)

    Ling, Chi-Hai; Chen, Cheng-lung

    1989-01-01

    The generalized viscoplastic fluid (GVF) model is used to derive the theoretical expressions of two-dimensional velocities and surface profile for debris flow established in a flume with bed driven by a conveyor belt. The rheological parameters of the GVF model are evaluated through the comparison of theoretical results with measured data. A slip velocity of the established (steady) nonuniform flow on the moving bed (i.e., the conveyor belt) is observed, and a relation between the slip velocity and the velocity gradient at the bed is derived. Two belts, one rough and the other smooth, were tested. The flow profile in the flume is found to be linear and dependent on the roughness of the belt, but not much on its speed.

  6. Debris bed cooling following an HCDA in a fast reactor. Final report

    International Nuclear Information System (INIS)

    Abdel-Khalik, S.I.

    1983-01-01

    Natural convection within simulated core debris beds has been experimentally and theoretically investigated. The effect of heating method on bed behavior has been found to be important. For directly-heated beds, variations of the downward and upward power fraction and Nusselt numbers with bed loading, power density, particle size, overlying fluid layer height and top surface boundary condition have been determined. Generalized correlations for the upward and downward Nusselt numbers as functions of the internal Rayleigh number have been obtained. Particle tracing techniques have been used to visualize the flow patterns within the bed and overlying fluid layer. The temperature distributions within the bed and overlying fluid layer have also been measured. The experimental data have been compared with COMMIX-lA predictions. Poor agreement has been obtained for both the integral quantities, i.e. downward and upward power fractions and Nusselt numbers, as well as the steady state velocity and temperature distributions. The code does not correctly predict either the magnitude or even the trend of the data

  7. Comparison of Two Phase Pressure Drop Models in 1-D Top Flooded Debris Bed

    International Nuclear Information System (INIS)

    Lee, Moon Eon; Park, Jin Ho; Kim, Eun ho; Park, Hyun Sun

    2016-01-01

    The dry out of coolant inside debris bed can be considered as the limitation of cooling in the conservative point of view and the heat flux through whole bed at the situation is named as Dryout Heat Flux (DHF). The modeling of DHF for debris bed started from early 1980s by several researchers. It is known that DHF mainly occurs by hydrodynamic limitation inside porous media. Therefore, there have been following attempts to capture flow resistance in porous media, precisely. Up to date, although there are about seven pressure drop models available in literatures, it is hard to find comparison of those models with a wide range of DHF experimental data. The one attempt[9] was conducted in 2013, but due to lack of consideration of the capillary pressure in his work, the DHF values that he calculated seem to be underestimated, especially in the range of the small particle diameter cases. In this research, the importance of capillary pressure in the comparison of pressure drop model with experimental data was checked and model selection among pressure drop models for the DHF calculation was also conducted. The model comparison with 108 experimental data from various conditions has been conducted and the Schmidt model shows the best agreement to the experimental data although Reed, Rahman model also show similar results.

  8. Comparison of Two Phase Pressure Drop Models in 1-D Top Flooded Debris Bed

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Moon Eon; Park, Jin Ho; Kim, Eun ho; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of)

    2016-05-15

    The dry out of coolant inside debris bed can be considered as the limitation of cooling in the conservative point of view and the heat flux through whole bed at the situation is named as Dryout Heat Flux (DHF). The modeling of DHF for debris bed started from early 1980s by several researchers. It is known that DHF mainly occurs by hydrodynamic limitation inside porous media. Therefore, there have been following attempts to capture flow resistance in porous media, precisely. Up to date, although there are about seven pressure drop models available in literatures, it is hard to find comparison of those models with a wide range of DHF experimental data. The one attempt[9] was conducted in 2013, but due to lack of consideration of the capillary pressure in his work, the DHF values that he calculated seem to be underestimated, especially in the range of the small particle diameter cases. In this research, the importance of capillary pressure in the comparison of pressure drop model with experimental data was checked and model selection among pressure drop models for the DHF calculation was also conducted. The model comparison with 108 experimental data from various conditions has been conducted and the Schmidt model shows the best agreement to the experimental data although Reed, Rahman model also show similar results.

  9. Characterizing Debris Disks in the Late Stages of Planet Formation

    Science.gov (United States)

    White, Jacob

    2018-01-01

    The planet formation process shapes the morphology and grain size distribution of circumstellar disks, encoding the formation history of a given system. Remnants of planet formation, such as comets and asteroids, collisionally evolve and can replenish the dust and small solids that would otherwise be cleared on short timescales. These grains are observed through reprocessed starlight at submm to cm wavelengths.The spectrum of the mm/cm emission reveals details of the grain population. However, one confounding parameter in studying these grains around stars is the stars themselves. The emission from stars in the mm/cm is nontrivial and generally not well-constrained. I will present examples of debris systems (HD 141569 and Fomalhaut) studied by ALMA and the VLA, in which unconstrained stellar emission may be contributing to the observed flux densities. Such contamination in turn biases the inferred emission from the disk and the corresponding dust properties. In some cases, the behavior of the observed A/B stars can exhibit an emission profile that has similarities to that of the Sun's mm/cm emission, although the same processes are not thought to necessarily occur in the atmospheres of massive stars.To address the uncertainty in stellar emission at mm/cm wavelengths, we present ongoing radio observations (JCMT, SMA, VLA) of Sirius A, which is a bright, nearby star with no known debris. We seek to use this system to set an observationally determined standard for stellar atmosphere modeling and debris disk studies around A stars, as well as to take the first step toward characterizing potential intrinsic uncertainty in stellar emission at these wavelengths. This talk will highlight the effort to characterize stellar atmospheres through a project known as MESAS (Measuring the Emission of Stellar Atmospheres at Submillimeter/millimeter wavelengths) which is imperative to the success of current and future debris disk studies.

  10. Dryout heat flux in a debris bed with forced coolant flow from below

    International Nuclear Information System (INIS)

    Bang, Kwang-Hyun; Kim, Jong-Myung

    2004-01-01

    The objective of the present study is to experimentally investigate the enhancement of dryout heat flux in debris beds with coolant flow from below. The experimental facility consists mainly of an induction heater (40 kW, 35 kHz), a double-wall quartz-tube test section containing steel-particle bed and coolant injection and recovery condensing loop. A fairly uniform heating of particle bed was achieved by induction heating. This paper reports the experimental data for 5 mm particle bed and 300 mm bed height. The dryout heat rate data were obtained of both top-flooding case and forced coolant injection from below with the injection mass flux up to 1.5 kg/m 2 s. For the top-flooded case, the volumetric dryout heat rate was about 4 MW/m 3 and it increased as the rate of coolant injection from below was increased. At the coolant injection mass flux of 1.5 kg/m 2 s, the volumetric dryout heat rate was about 10 MW/m 3 , the enhancement factor was more than two. (author)

  11. Unsteady void measurements within debris beds using high speed X-ray tomography

    Energy Technology Data Exchange (ETDEWEB)

    Laurien, E., E-mail: Laurien@ike.uni-stuttgart.de; Stürzel, T., E-mail: thilo.stuerzel@stihl.de; Zhou, M., E-mail: mi.zhou@ike.uni-stuttgart.de

    2017-02-15

    Highlights: • A high speed X-ray tomography facility has been built for the investigation on two-phase flow. • The two-phase flow through beds of packed plastic spheres has been investigated in the facility. • 3D-reconstructions from the measurements show the fluxes in the two-phase flow. • The gas fraction has been calculated from the reconstruction and used for validation of the modeling. • A new bed with closest regular spheres arrangement has been manufactured by 3D-plotter and used in the measurement. - Abstract: Two-phase flow and boiling within debris beds representing a destroyed reactor core after a severe accident with core fragmentation can be simulated by using the porous media approach. In this approach, a local pressure drop and the heat transfer between the solid debris particles and the two-phase flow is modelled with the help flow-pattern maps, in which the boundaries between bubbly, slug, and annular flow are assumed. In order to support further understanding of these flows we have developed a very fast X-ray measurement device to visualize the 3D-void distribution within particle beds or porous media, which are otherwise un-accessible internally. The experimental setup uses a scanned electron beam directed in circles on a tungsten target to generate the X-rays. The particle bed, which has a diameter of 70 mm, is located between this target and a field of 256 X-ray detectors, which are arranged on a circle concentric to the target. The void distribution is reconstructed numerically from the attenuation of signals, which penetrates the particle bed and the two-phase flow inside. A 3D frame rate of up to 1000 Hz can be reached. The spatial resolution is such that bubbles with a diameter > 1.7 mm can be detected. We have investigated two-phase flows air/water through beds of packed plastic spheres (diameter between 3 and 15 mm) as well as through plastic beds, which were manufactured using a ‘3D-plotter’. Flow patterns can be

  12. Simulation and uncertainties of the heat transfer from a heat-generating DEBRIS bed in the lower plenum

    International Nuclear Information System (INIS)

    Schaaf, K.; Trambauer, K.

    1999-01-01

    The findings of the TMI-2 post-accident analyses indicated that internal cooling mechanisms may have a considerable potential to sustain the vessel integrity after a relocation of core material to the lower plenum, provided that water is continuously available in the RPV. Numerous analytical and experimental research activities are currently underway in this respect. This paper illustrates some major findings of the experimental work on internal cooling mechanisms and describes the limitations and the uncertainties in the simulation of the heat transfer processes. Reference is made especially to the joint German DEBRIS/ RPV research program, which encompasses the experimental investigation of the thermal-hydraulics in gaps, of the heat transfer within a particulate debris bed, and of the high temperature performance of vessel steel, as well as the development of simulation models for the heat transfer in the lower head and the structural response of the RPV. In particular, the results of uncertainty and sensitivity analyses are presented, which have been carried out at GRS using an integral model that describes the major phenomena governing the long-term integrity of the reactor vessel. The investigation of a large-scale relocation indicated that the verification of a gap cooling mechanism as an inherent mechanism is questionable in terms of a stringent probabilistic uncertainty criterion, as long as the formation of a large molten pool cannot be excluded. (author)

  13. Numerical models for the analysis of thermal behavior and coolability of a particulate debris bed in reactor lower head

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Kwang Il; Kim, Sang Baik; Kim, Byung Seok [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-04-01

    This report provides three distinctive, but closely related numerical models developed for the analysis of thermal behavior and coolability of a particulate debris bed that is may be formed inside the reactor lower head during severe accident late phases. The first numerical module presented in the report, MELTPRO-DRY, is used to analyze numerically heat-up and melting process of the dry particle bed, downward- and sideward-relocation of the liquid melt under gravity force and capillary force acting among porous particles, and solidification of the liquid melt relocated into colder region. The second module, MELTPROG-WET, is used to simulate numerically the cooling process of the particulate debris bed under the existence of water, which is subjected to two types of numerical models. The first type of WET module utilizes distinctive models that parametrically simulate the water cooling process, that is, quenching region, dryout region, and transition region. The choice of each parametric model depends on temperature gradient between the cooling water and the debris particles. The second type of WET module utilizes two-phase flow model that mechanically simulates the cooling process of the debris bed. For a consistent simulation from the water cooling to the dryout debris bed, on the other hand, the aforementioned two modules, MELTPROG-DRY and MELTPROG-WET, were integrated into a single computer program DBCOOL. Each of computational models was verified through limited applications to a heat-generating particulate bed contained in the rectangular cavity. 22 refs., 5 figs., 2 tabs. (Author)

  14. COLLISIONAL DEBRIS AS LABORATORIES TO STUDY STAR FORMATION

    International Nuclear Information System (INIS)

    Boquien, M.; Duc, P.-A.; Wu, Y.; Charmandaris, V.; Lisenfeld, U.; Braine, J.; Brinks, E.; Iglesias-Paramo, J.; Xu, C. K.

    2009-01-01

    In this paper we address the question of whether star formation (SF) is driven by local processes or the large-scale environment. To do so, we investigate SF in collisional debris where the gravitational potential well and velocity gradients are shallower and compare our results with previous work on SF in noninteracting spiral and dwarf galaxies. We have performed multiwavelength spectroscopic and imaging observations (from the far-ultraviolet to the mid-infrared) of six interacting systems, identifying a total of 60 star-forming regions in their collision debris. Our analysis indicates that in these regions (1) the emission of the dust is at the expected level for their luminosity and metallicity, (2) the usual tracers of SFR display the typical trend and scatter found in classical star-forming regions, and (3) the extinction and metallicity are not the main parameters governing the scatter in the properties of intergalactic star-forming regions; age effects and variations in the number of stellar populations seem to play an important role. Our work suggests that local properties such as column density and dust content, rather than the large-scale environment seem to drive SF. This means that intergalactic star-forming regions can be used as a reliable tool to study SF.

  15. Debris bed coolability using a 3-D two phase model in a porous medium

    Energy Technology Data Exchange (ETDEWEB)

    Bechaud, C.; Duval, F.; Fichot, F. [CEA Cadarache, Inst. de Protection et de Surete Nucleaire13 - Saint-Paul-lez-Durance (France); Quintard, M. [Institut de Mecanique des Fluides de Toulouse, 31 (France); Parent, M. [CEA Grenoble, Dept. de Thermohydraulique et de Physique, 38 (France)

    2001-07-01

    During a severe nuclear accident, a part of the molten corium resulting from the core degradation may relocate in the lower plenum of the reactor vessel. In order to predict the safety margin of the reactor under such conditions, the coolability of this porous heat-generating medium is evaluated in this study and compared with other investigations. In this work, conservation equations derived for debris beds are implemented in the three dimensional thermal-hydraulic module of the CATHARE code. The coolant flow is a two phase flow with phase change. The momentum balance equation for each fluid phase is an extension of Darcy's law. This extension takes into account the capillary effects between the two phases, the relative permeabilities and passabilities of each phase, the interfacial drag force between liquid and gas, and the porous bed configuration (porosity, particle diameter,... ). The model developed is three-dimensional which is important to better predict the flow in configuration such as counter-current flow or to emphasize preferential ways induced by porous geometry. The energy balance equations of the three phases (liquid, gas and solid phase) are obtained by a volume averaging process of the local conservation equations. In this method, the local thermal non-equilibrium between the three phases is considered and the heat exchanges, the phase change rate as well as the thermal dispersion coefficients are calculated as a function of the local geometry of the porous medium. Such a method allows the numerical estimation of these thermal properties which are very difficult to determine experimentally. This feature is a great advantage of this approach. After a brief description of the thermal-hydraulic model, one-dimensional predictions of critical dryout fluxes are presented and compared with results from the literature. Reasonable agreement is obtained. Then a two-dimensional calculation is presented and shows the influence of the porous medium

  16. Experiments and procedures for bottom-heating heat-transfer experiments through UO2 debris beds in sodium

    International Nuclear Information System (INIS)

    Sowa, E.S.; Pedersen, D.R.; Pavlik, J.; Purviance, R.

    1982-01-01

    Real materials experiments in heat transfer through beds of UO 2 in sodium have been performed at Argonne National Laboratory over a period of years. The most recent method utilizes the resistive heating in a sheet tungsten filament located at the base of the debris container. A schematic diagram of the apparatus is shown. The tungsten is clamped between two water cooled copper electrodes. The filament is a sheet of tungsten 0.15 mm thick, 5 cm wide and 18 cm long. Two 6.5 mm thick sheets of boron nitride sandwich the filament. The upper face of the upper boron nitride sheet is in intimate contact with the bottom of the debris container. Temperatures are measured at various levels in the bed as well as in the boron nitride plate. In addition, the sodium pool temperature is measured by the thermocouple. The heat transferral through the bed is measured by the temperature difference and mass flowrate in a NaK condenser located above the debris bed. The NaK inlet and outlet temperatures are recorded individually, as well as, differentially

  17. Non-local rheology of stony debris flow propagating over a cohesionless sediment bed

    Science.gov (United States)

    Lanzoni, Stefano; Gregoretti, Carlo

    2016-04-01

    normal to the flow, with particular attention to the role played by frictional stresses near to the movable bed over which the debris flow propagates.

  18. Debris disks as signposts of terrestrial planet formation

    Science.gov (United States)

    Raymond, S. N.; Armitage, P. J.; Moro-Martín, A.; Booth, M.; Wyatt, M. C.; Armstrong, J. C.; Mandell, A. M.; Selsis, F.; West, A. A.

    2011-06-01

    There exists strong circumstantial evidence from their eccentric orbits that most of the known extra-solar planetary systems are the survivors of violent dynamical instabilities. Here we explore the effect of giant planet instabilities on the formation and survival of terrestrial planets. We numerically simulate the evolution of planetary systems around Sun-like stars that include three components: (i) an inner disk of planetesimals and planetary embryos; (ii) three giant planets at Jupiter-Saturn distances; and (iii) an outer disk of planetesimals comparable to estimates of the primitive Kuiper belt. We calculate the dust production and spectral energy distribution of each system by assuming that each planetesimal particle represents an ensemble of smaller bodies in collisional equilibrium. Our main result is a strong correlation between the evolution of the inner and outer parts of planetary systems, i.e. between the presence of terrestrial planets and debris disks. Strong giant planet instabilities - that produce very eccentric surviving planets - destroy all rocky material in the system, including fully-formed terrestrial planets if the instabilities occur late, and also destroy the icy planetesimal population. Stable or weakly unstable systems allow terrestrial planets to accrete in their inner regions and significant dust to be produced in their outer regions, detectable at mid-infrared wavelengths as debris disks. Stars older than ~100 Myr with bright cold dust emission (in particular at λ ~ 70 μm) signpost dynamically calm environments that were conducive to efficient terrestrial accretion. Such emission is present around ~16% of billion-year old Solar-type stars. Our simulations yield numerous secondary results: 1) the typical eccentricities of as-yet undetected terrestrial planets are ~0.1 but there exists a novel class of terrestrial planet system whose single planet undergoes large amplitude oscillations in orbital eccentricity and inclination; 2) by

  19. Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

    Directory of Open Access Journals (Sweden)

    An Ping Shu

    2017-04-01

    Full Text Available Non-homogeneous debris flows generally occur during the rainy seasons in Southwest China, and have received considerable attention in the literature. Regarding the complexity in debris flow dynamics, experimental approaches have proven to be effective in revealing the formative mechanism for debris flow, and quantifying the relations between the various influencing factors with debris-flow formation and subsequent transport processes. Therefore, a flume-based and experimental study was performed at the Debris Flow Observation and Research Station of Jiangjia Gully in Yunnan Province, to theoretically analyze favorable conditions for debris-flow formation and initial transport by selecting the median particle size d50, flow rate Q, vertical grading coefficient ψ, slopes S, and the initial soil water contents W as the five variables for investigation. To achieve this, an optimal combination of these variables was made through an orthogonal experimental design to determine their relative importance upon the occurrence and initial mobilization behavior of a debris flow and to further enhance our insight into debris-flow triggering and transport mechanisms.

  20. Basal interstitial water pressure in laboratory debris flows over a rigid bed in an open channel

    Directory of Open Access Journals (Sweden)

    N. Hotta

    2012-08-01

    Full Text Available Measuring the interstitial water pressure of debris flows under various conditions gives essential information on the flow stress structure. This study measured the basal interstitial water pressure during debris flow routing experiments in a laboratory flume. Because a sensitive pressure gauge is required to measure the interstitial water pressure in shallow laboratory debris flows, a differential gas pressure gauge with an attached diaphragm was used. Although this system required calibration before and after each experiment, it showed a linear behavior and a sufficiently high temporal resolution for measuring the interstitial water pressure of debris flows. The values of the interstitial water pressure were low. However, an excess of pressure beyond the hydrostatic pressure was observed with increasing sediment particle size. The measured excess pressure corresponded to the theoretical excess interstitial water pressure, derived as a Reynolds stress in the interstitial water of boulder debris flows. Turbulence was thought to induce a strong shear in the interstitial space of sediment particles. The interstitial water pressure in boulder debris flows should be affected by the fine sediment concentration and the phase transition from laminar to turbulent debris flow; this should be the subject of future studies.

  1. FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

    International Nuclear Information System (INIS)

    Jantzen, C

    2006-01-01

    Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO 2 and steam, and nitrate/nitrite components, if any, to N 2 . The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO 4 , I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the 2 durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form

  2. FLUIDIZED BED STEAM REFORMER MONOLITH FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C

    2006-12-22

    Fluidized Bed Steam Reforming (FBSR) is being considered as an alternative technology for the immobilization of a wide variety of aqueous high sodium containing radioactive wastes at various DOE facilities in the United States. The addition of clay, charcoal, and a catalyst as co-reactants converts aqueous Low Activity Wastes (LAW) to a granular or ''mineralized'' waste form while converting organic components to CO{sub 2} and steam, and nitrate/nitrite components, if any, to N{sub 2}. The waste form produced is a multiphase mineral assemblage of Na-Al-Si (NAS) feldspathoid minerals with cage-like structures that atomically bond radionuclides like Tc-99 and anions such as SO{sub 4}, I, F, and Cl. The granular product has been shown to be as durable as LAW glass. Shallow land burial requires that the mineralized waste form be able to sustain the weight of soil overburden and potential intrusion by future generations. The strength requirement necessitates binding the granular product into a monolith. FBSR mineral products were formulated into a variety of monoliths including various cements, Ceramicrete, and hydroceramics. All but one of the nine monoliths tested met the <2g/m{sup 2} durability specification for Na and Re (simulant for Tc-99) when tested using the Product Consistency Test (PCT; ASTM C1285). Of the nine monoliths tested the cements produced with 80-87 wt% FBSR product, the Ceramicrete, and the hydroceramic produced with 83.3 wt% FBSR product, met the compressive strength and durability requirements for an LAW waste form.

  3. Reinterpretation of the formation of the "crooked moraine" of the debris-covered Hatunraju Glacier (Cordillera Blanca, Perú)

    Science.gov (United States)

    Iturrizaga, L.

    2012-04-01

    The Hatunraju Glacier (9°00'S/70°40'W) is located in the Parón valley in the northern part of the Cordillera Blanca. The almost 4 km long and steeply inclined glacier flows down from the Huandoy-N-Side (6395 m) into the Parón valley to an elevation of 4250 m a.s.l.. The extremely narrow glacier is in its entire ablation area heavily debris-covered. It is one of the few glaciers, which dam with its debris-mantled glacier tongue a main river in this mountain range. In this case the Hatunraju glacier produces the largest glacier-dammed lake in the Cordillera Blanca, the Laguna Parón. In some other aspects, this glacier proves to be distinct from the majority of the glaciers in the Cordillera Blanca: It is flowing on an almost up to 250 m high moraine pedestal ("moraine-dammed raised bed glacier") and the glacier makes a bend of almost 90° when entering into the main valley. The present paper focuses in particular on the last point: the formation of the so called "crooked moraine". It has been explained by Lliboutry (1977) as a result of a glacier lake outburst and the subsequent destruction of the latero-frontal moraine. The later process supposed to be the trigger of the abrupt change in the flow direction of the lower part of the glacier. Recent investigations suggest an alternative genesis of the crooked moraine considering the distinct phases of the glaciation history of the Parón valley. The here proposed formation pattern is also paradigmatic for other crooked debris-covered glaciers, especially in High Asia. Comparative examples will be provided from the Karakoram and Himalayas. The research work on the Hatunraju Glacier is part of a project on the glacial geomorphology in the Tropical Andes financed by the Alexander von Humboldt-Foundation.

  4. Assessment of capability of models for prediction of pressure drop and dryout heat flux in a heat generating particulate debris bed

    International Nuclear Information System (INIS)

    Kulkarni, P.P.; Nayak, A.K.; Rashid, M.; Kulenovic, R.

    2009-01-01

    During a severe accident in a light water reactor, the core can melt and be relocated to the lower plenum of the reactor pressure vessel. There it can form a particulate debris bed due to the possible presence of water. This bed, if not quenched in time, can lead to the failure of the pressure vessel because of the insufficient heat removal of decay heat in the debris bed. Therefore, addressing the issue of coolability behaviour of heat generating particulate debris bed is of prime importance in the framework of severe accident management strategies, particularly in case of above mentioned late phase scenario of an accident. In order to investigate the coolability behaviour of particulate debris bed, experiments were carried out at IKE test facility 'DEBRIS' on particle beds of irregularly shaped particles mixed with spheres under top- and bottom-flooding condition. The pressure drop and dryout heat flux (DHF) were measured for top- and bottom-flooding conditions. For top-flooding conditions, it was found that the pressure gradients are all smaller than the hydrostatic pressure gradient of water, indicating an important role of the counter-current interfacial shear stress of the two-phase flow. For bottom-flooding with a relatively high liquid inflow velocity, the pressure gradient increases consistently with the vapour velocity and the fluid-particle drags become important. Also, with additional forced liquid inflow from the bottom, the DHF increases dramatically. In all the cases, it was found that the DHF is significantly larger with bottom-flooding condition compared to top-flooding condition. Different models such as Lipinski, Reed, Tung and Dhir, Hu and Theophanous, and Schulenberg and Mueller have been used to predict the pressure drop characteristics and the DHF of heat generating particulate debris beds. Comparison is made among above mentioned models and experimental results for DHF and pressure drop characteristics. Considering the overall trend in

  5. Carbon dioxide hydrate formation in a fixed-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fan, S.; Lang, X. [South China Univ. of Technology, Guangzhou (China). Key Laboratory of Enhanced Heat Transfer and Energy Conservation; Wang, Y.; Liang, D. [Chinese Academy of Sciences, Guangzhou (China). Guangzhou Inst. of Energy Conversion and Guangzhou Center of Natural Gas Hydrate; Sun, X.; Jurcik, B. [Air Liquide Laboratories, Tsukuba (Japan)

    2008-07-01

    Gas hydrates are thermodynamically stable at high pressures and near the freezing temperature of pure water. Methane hydrates occur naturally in sediments in the deep oceans and permafrost regions and constitute an extensive hydrocarbon reservoir. Carbon dioxide (CO{sub 2}) hydrates are of interest as a medium for marine sequestration of anthropogenic carbon dioxide. Sequestering CO{sub 2} as hydrate has potential advantages over most methods proposed for marine CO{sub 2} sequestration. Because this technique requires a shallower depth of injection when compared with other ocean sequestration methods, the costs of CO{sub 2} hydrate sequestration may be lower. Many studies have successfully used different continuous reactor designs to produce CO{sub 2} hydrates in both laboratory and field settings. This paper discussed a study that involved the design and construction of a fixed-bed reactor for simulation of hydrate formation system. Water, river sands and carbon dioxide were used to simulate the seep kind of hydrate formation. Carbon dioxide gas was distributed as small bubbles to enter from the bottom of the fixed-bed reactor. The paper discussed the experimental data and presented a diagram of the gas hydrate reactor system. The morphology as well as the reaction characters of CO{sub 2} hydrate was presented in detail. The results were discussed in terms of experimental phenomena and hydrate formation rate. A mathematical model was proposed for describing the process. 17 refs., 7 figs.

  6. Evolution of Fine-Grained Channel Margin Deposits behind Large Woody Debris in an Experimental Gravel-Bed Flume

    Science.gov (United States)

    ONeill, B.; Marks, S.; Skalak, K.; Puleo, J. A.; Wilcock, P. R.; Pizzuto, J. E.

    2014-12-01

    Fine grained channel margin (FGCM) deposits of the South River, Virginia sequester a substantial volume of fine-grained sediment behind large woody debris (LWD). FGCM deposits were created in a laboratory setting meant to simulate the South River environment using a recirculating flume (15m long by 0.6m wide) with a fixed gravel bed and adjustable slope (set to 0.0067) to determine how fine sediment is transported and deposited behind LWD. Two model LWD structures were placed 3.7 m apart on opposite sides of the flume. A wire mesh screen with attached wooden dowels simulated LWD with an upstream facing rootwad. Six experiments with three different discharge rates, each with low and high sediment concentrations, were run. Suspended sediment was very fine grained (median grain size of 3 phi) and well sorted (0.45 phi) sand. Upstream of the wood, water depths averaged about 0.08m, velocities averaged about 0.3 m/s, and Froude numbers averaged around 0.3. Downstream of the first LWD structure, velocities were reduced tenfold. Small amounts of sediment passed through the rootwad and fell out of suspension in the area of reduced flow behind LWD, but most of the sediment was carried around the LWD by the main flow and then behind the LWD by a recirculating eddy current. Upstream migrating dunes formed behind LWD due to recirculating flow, similar to reattachment bars documented in bedrock canyon rivers partially obstructed by debouching debris fans. These upstream migrating dunes began at the reattachment point and merged with deposits formed from sediment transported through the rootwad. Downstream migrating dunes formed along the channel margin behind the LWD, downstream of the reattachment point. FGCM deposits were about 3 m long, with average widths of about 0.8 m. Greater sediment concentration created thicker FGCM deposits, and higher flows eroded the sides of the deposits, reducing their widths.

  7. Cross-stratified Wood: Enigmatic Woody Debris Deposits in Warm-Polar Fluvial Sediments (Pliocene Beaufort Formation, Nunavut)

    Science.gov (United States)

    Davies, N. S.; Gosse, J. C.; Rybczynski, N.

    2012-04-01

    Woody debris has been an important sediment component and a significant geomorphic agent in pristine fluvial systems since the Devonian. In recent years a large volume of research has focussed on various aspects of the importance of woody debris within the fluvial realm; from the evolutionary significance of fossil wood accumulations in the rock record to studies of the biogeomorphological and ecological importance of woody debris in modern rivers. In this presentation we describe cross-stratified woody debris deposits comprising organic detritus from a boreal-type treeline forest that included species of pine, birch, poplar, alder, spruce, eastern cedar, and larch, in both shrub and tree form. The cross-stratified wood is an enigmatic subset of fine woody debris which, to our knowledge, has never before been described from either the global stratigraphic record or modern fluvial environments. The deposits we describe are located within the Pliocene Beaufort Formation on Meighen Island, Nunavut, Canada, at a latitude of 80°N, and are compared with other cross-stratified woody debris deposits that have been noted elsewhere in the Pliocene of the Canadian Arctic. We make the robust observation that these deposits appear to be geographically and stratigraphically restricted to polar latitudes from a period of warm climatic conditions during the Pliocene (15-20 °C warmer mean annual temperature than the present day). In this regard it is possible to speculate that the transport of large amounts of woody debris as bedload is potentially a unique feature of forested high latitude rivers. Such bedload deposition requires a large amount of woody debris with a greater density than the fluid transporting it. The softwood composition of the debris suggests that this was most likely attained by saturation and subsequent entrainment of extensive accumulations of deadwood, promoted by unusually high rates of tree mortality and low rates of bacterial decomposition arising from

  8. Sediment Transport on Continental Shelves: Storm Bed Formation and Preservation in Heterogeneous Sediments

    Science.gov (United States)

    2012-01-01

    occurred during the Cretaceous period. The simulated storm bed for such an extratropical cyclone that lasts 4 days was deposited as deep as 75 m and had...Int. Assoc. Sedimentol. Spec. Publ. (2012) 44, 295-310 Sediment transport on continental shelves: storm bed formation and preservation in...xDept. of Earth Science, Memorial University of Newfoundland, St. Johns, Newfoundland, Canada ABSTRACT Many storm beds are constructed of silt/sand

  9. Brief analysis on relationship between red beds and sandstone-type uranium ore-formation

    International Nuclear Information System (INIS)

    Ji Zengxian

    2006-01-01

    Red beds are sandy gravel beds deposited under the arid and hot climates and correspondent to the oxidation environment of continental basins. As an exogenetic epigenetic uranium deposit, the formation of the sandstone-type uranium deposit needs a large chronologic gap between the diagenesis and the subsequent uranium metallogenesis of the ore-hosting target layer with a sedimentary discontinuity and an alternative humid-arid climate. Red beds are the product of this time. The evolutionary times of red beds are in accordance with the formation of the sandstone-type uranium deposit. Both domestic and abroad researches indicate that each times evolution of a red bed might be associated with uranium ore-formation in one or more sandstone layers in the region. In China, red beds are developed in many geologic periods, but sandstone-type uranium mineralization occurs mostly in Mesozoic-Cenozoic. Taking five known sandstone-type uranium deposits as examples, the author makes a primary analysis on the relationship between red beds and the subsequent sandstone-type uranium mineralization. It is suggested that the deposition of red beds and sandstone-type uranium metallogenesis are of 'cogenesis and coexistence' and that the deposition of red beds and its evolutionary times can be regarded as the prerequisites to judge the potential of sandstone-type uranium mineralization in a Mesozoic-Cenozoic sedimentary basin. (authors)

  10. Changes in markers of bone formation and resorption in a bed rest model of weightlessness

    Science.gov (United States)

    Lueken, S. A.; Arnaud, S. B.; Taylor, A. K.; Baylink, D. J.

    1993-01-01

    To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

  11. Ichnofauna from the Harbans Bed of the Badhaura Formation ...

    Indian Academy of Sciences (India)

    Badhaura Formation (Sterlitmakian) representing marine rocks deposited following the Late Palaeozoic glaciation ..... distinguish D. lyelli from all other species of the ichnogenus ..... fossils and the Muensteria–Taenidium problem; Palaeon-.

  12. Determining the Frequency of Dry Lake Bed Formation in Semi-Arid Mongolia From Satellite Data

    Directory of Open Access Journals (Sweden)

    Yuta Demura

    2017-12-01

    Full Text Available In the Mongolian Plateau, the desert steppe, mountains, and dry lake bed surfaces may affect the process of dust storm emissions. Among these three surface types, dry lake beds are considered to contribute a substantial amount of global dust emissions and to be responsible for “hot spots” of dust outbreaks. The land cover types in the study area were broadly divided into three types, namely desert steppe, mountains, and dry lake beds, by a classification based on Normalized Difference Water Index (NDWI calculated from MODIS Terra satellite images, and Digital Elevation Model (DEM. This dry lake beds extracting method using remote sensing offers a new technique for identifying dust hot spots and potential untapped groundwater in the dry lands of the Gobi region. In the study area, frequencies of dry lake bed formation were calculated during the period of 2001 to 2014. The potential dry lake area corresponded well with the length of the river network based on hydrogeological characterization (R2 = 0.77, p < 0.001. We suggest that the threshold between dry lake bed areas and the formation of ephemeral lakes in semi-arid regions is eight days of total precipitation.

  13. FLUIDIZED BED STEAM REFORMER (FBSR) PRODUCT: MONOLITH FORMATION AND CHARACTERIZATION

    International Nuclear Information System (INIS)

    Jantzen, C

    2006-01-01

    The most important requirement for Hanford's low activity waste (LAW) form for shallow land disposal is the chemical durability of the product. A secondary, but still essential specification, is the compressive strength of the material with regards to the strength of the material under shallow land disposal conditions, e.g. the weight of soil overburden and potential intrusion by future generations, because the term ''near-surface disposal'' indicates disposal in the uppermost portion, or approximately the top 30 meters, of the earth's surface. The THOR(reg s ign) Treatment Technologies (TTT) mineral waste form for LAW is granular in nature because it is formed by Fluidized Bed Steam Reforming (FBSR). As a granular product it has been shown to be as durable as Hanford's LAW glass during testing with ASTM C-1285-02 known as the Product Consistency Test (PCT) and with the Single Pass Flow Through Test (SPFT). Hanford Envelope A and Envelope C simulants both performed well during PCT and SPFT testing and during subsequent performance assessment modeling. This is partially due to the high aluminosilicate content of the mineral product which provides a natural aluminosilicate buffering mechanism that inhibits leaching and is known to occur in naturally occurring aluminosilicate mineral analogs. In order for the TTT Na-Al-Si (NAS) granular mineral product to meet the compressive strength requirements (ASTM C39) for a Hanford waste form, the granular product needs to be made into a monolith or disposed of in High Integrity Containers (HIC's). Additionally, the Hanford intruder scenario for disposal in the Immobilized Low Activity Waste (ILAW) trench is mitigated as there is reduced intruder exposure when a waste form is in a monolithic form. During the preliminary testing of a monolith binder for TTT's FBSR mineral product, four parameters were monitored: (1) waste loading (not optimized for each waste form tested); (2) density; (3) compressive strength; and (4

  14. Hydrology and Hydraulic Properties of a Bedded Evaporite Formation

    International Nuclear Information System (INIS)

    BEAUHEIM, RICHARD L.; ROBERTS, RANDALL M.

    2000-01-01

    The Permian Salado Formation in the Delaware Basin of New Mexico is an extensively studied evaporite deposit because it is the host formation for the Waste Isolation Pilot Plant, a repository for transuranic wastes. Geologic and hydrologic studies of the Salado conducted since the mid-1970's have led to the development of a conceptual model of the hydrogeology of the formation that involves far-field permeability in anhydrite layers and at least some impure halite layers. Pure halite layers and some impure halite layers may not possess an interconnected pore network adequate to provide permeability. Pore pressures are probably very close to lithostatic pressure. In the near field around an excavation, dilation, creep, and shear have created and/or enhanced permeability and decreased pore pressure. Whether flow occurs in the far field under natural gradients or only after some threshold gradient is reached is unknown. If far-field flow does occur, mean pore velocities are probably on the order of a meter per hundreds of thousands to tens of millions of years. Flow dimensions inferred from most hydraulic-test responses are subradial, which is believed to reflect channeling of flow through fracture networks, or portions of fractures, that occupy a diminishing proportion of the radially available space, or through percolation networks that are not ''saturated'' (fully interconnected). This is probably related to the directional nature of the permeability created or enhanced by excavation effects. Inferred values of permeability cannot be separated from their associated flow dimensions. Therefore, numerical models of flow and transport should include heterogeneity that is structured to provide the same flow dimensions as are observed in hydraulic tests. Modeling of the Salado Formation around the WIPP repository should also include coupling between hydraulic properties and the evolving stress field because hydraulic properties change as the stress field changes

  15. Characteristics of debris in the lower head of a BWR in different severe accident scenarios

    International Nuclear Information System (INIS)

    Phung, Viet-Anh; Galushin, Sergey; Raub, Sebastian; Goronovski, Andrei; Villanueva, Walter; Kööp, Kaspar; Grishchenko, Dmitry; Kudinov, Pavel

    2016-01-01

    Highlights: • Station blackout scenario with delayed recovery of safety systems in a Nordic BWR is considered. • Genetic algorithm and random sampling methods are used to explore accident scenario domain. • Main groups of scenarios are identified. • Ranges and distributions of characteristics of debris bed in the lower head are determined. - Abstract: Nordic boiling water reactors (BWRs) adopt ex-vessel debris cooling to terminate severe accident progression. Core melt released from the vessel into a deep pool of water is expected to fragment and form a coolable debris bed. Characteristics of corium melt ejection from the vessel determine conditions for molten fuel–coolant interactions (FCI) and debris bed formation. Non-coolable debris bed or steam explosion can threaten containment integrity. Vessel failure and melt ejection mode are determined by the in-vessel accident progression. Characteristics (such as mass, composition, thermal properties, timing of relocation, and decay heat) of the debris bed formed in the process of core relocation into the vessel lower plenum define conditions for the debris reheating, remelting, melt-vessel structure interactions, vessel failure and melt release. Thus core degradation and relocation are important sources of uncertainty for the success of the ex-vessel accident mitigation strategy. The goal of this work is improve understanding how accident scenario parameters, such as timing of failure and recovery of different safety systems can affect characteristics of the debris in the lower plenum. Station blackout scenario with delayed power recovery in a Nordic BWR is considered using MELCOR code. The recovery timing and capacity of safety systems were varied using genetic algorithm (GA) and random sampling methods to identify two main groups of scenarios: with relatively small ( 100 tons) amount of relocated debris. The domains are separated by the transition regions, in which relatively small variations of the input

  16. Characteristics of debris in the lower head of a BWR in different severe accident scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Phung, Viet-Anh, E-mail: vaphung@kth.se; Galushin, Sergey, E-mail: galushin@kth.se; Raub, Sebastian, E-mail: raub@kth.se; Goronovski, Andrei, E-mail: andreig@kth.se; Villanueva, Walter, E-mail: walterv@kth.se; Kööp, Kaspar, E-mail: kaspar@safety.sci.kth.se; Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se

    2016-08-15

    Highlights: • Station blackout scenario with delayed recovery of safety systems in a Nordic BWR is considered. • Genetic algorithm and random sampling methods are used to explore accident scenario domain. • Main groups of scenarios are identified. • Ranges and distributions of characteristics of debris bed in the lower head are determined. - Abstract: Nordic boiling water reactors (BWRs) adopt ex-vessel debris cooling to terminate severe accident progression. Core melt released from the vessel into a deep pool of water is expected to fragment and form a coolable debris bed. Characteristics of corium melt ejection from the vessel determine conditions for molten fuel–coolant interactions (FCI) and debris bed formation. Non-coolable debris bed or steam explosion can threaten containment integrity. Vessel failure and melt ejection mode are determined by the in-vessel accident progression. Characteristics (such as mass, composition, thermal properties, timing of relocation, and decay heat) of the debris bed formed in the process of core relocation into the vessel lower plenum define conditions for the debris reheating, remelting, melt-vessel structure interactions, vessel failure and melt release. Thus core degradation and relocation are important sources of uncertainty for the success of the ex-vessel accident mitigation strategy. The goal of this work is improve understanding how accident scenario parameters, such as timing of failure and recovery of different safety systems can affect characteristics of the debris in the lower plenum. Station blackout scenario with delayed power recovery in a Nordic BWR is considered using MELCOR code. The recovery timing and capacity of safety systems were varied using genetic algorithm (GA) and random sampling methods to identify two main groups of scenarios: with relatively small (<20 tons) and large (>100 tons) amount of relocated debris. The domains are separated by the transition regions, in which relatively small

  17. Analysis of the geological stability of a hypothetical radioactive waste repository in a bedded salt formation

    International Nuclear Information System (INIS)

    Tierney, M.S.; Lusso, F.; Shaw, H.R.

    1978-01-01

    This document reports on the development of mathematical models used in preliminary studies of the long-term safety of radioactive wastes deeply buried in bedded salt formations. Two analytical approaches to estimating the geological stability of a waste repository in bedded salt are described: (a) use of probabilistic models to estimate the a priori likelihoods of release of radionuclides from the repository through certain idealized natural and anthropogenic causes, and (b) a numerical simulation of certain feedback effects of emplacement of waste materials upon ground-water access to the repository's host rocks. These models are applied to an idealized waste repository for the sake of illustration

  18. Mechanisms of formation and destruction of nitrogen oxides during polyamide incineration in a fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Hahnel, F; Gadiou, R; Prado, G [Univ. de Haute Alsace, Mulhouse (France). Lab. de Gestion des Risques et Environnement

    1998-09-01

    In order to study the incineration of nitrogen-containing polymers, a fludized bed has been built. This paper reports the results for polyamide 6-6 incineration. The main nitrogen containing species have been identified, and the axial profiles of concentration of nitrogen oxides, HCN and NH3 have been measured. The main steps of decomposition of the polyamide were identified. We present an experimental investigation of the influence of operating parameters (temperature, excess air) on the formation and reduction of polymer combustion products. The yields of conversion of nitrogen to the different N-species have been calculated as a function of excess air in the fluidized bed. (orig.)

  19. Prediction of mass fraction of agglomerated debris in a LWR severe accident

    International Nuclear Information System (INIS)

    Kudinov, P.; Davydov, M.

    2011-01-01

    Ex-vessel termination of accident progression in Swedish type Boiling Water Reactors (BWRs) is contingent upon efficacy of melt fragmentation and solidification in a deep pool of water below reactor vessel. When liquid melt reaches the bottom of the pool it can create agglomerated debris and “cake” regions that increase hydraulic resistance of the bed and affect coolability of the bed. This paper discusses development and application of a conservative-mechanistic approach to quantify mass fractions of agglomerated debris. Experimental data from the DEFOR-A (Debris Bed Formation and Agglomeration) tests with high superheat of binary oxidic simulant material melt is used for validation of the methods. Application of the approach to plant accident analysis suggests that melt superheat has less significant influence on agglomeration of the debris than jet penetration depth. The paper also discusses the impact of the uncertainty in the jet disintegration and penetration behavior on the agglomeration mode map. (author)

  20. Debris disks as signposts of terrestrial planet formation. II. Dependence of exoplanet architectures on giant planet and disk properties

    Science.gov (United States)

    Raymond, S. N.; Armitage, P. J.; Moro-Martín, A.; Booth, M.; Wyatt, M. C.; Armstrong, J. C.; Mandell, A. M.; Selsis, F.; West, A. A.

    2012-05-01

    We present models for the formation of terrestrial planets, and the collisional evolution of debris disks, in planetary systems that contain multiple marginally unstable gas giants. We previously showed that in such systems, the dynamics of the giant planets introduces a correlation between the presence of terrestrial planets and cold dust, i.e., debris disks, which is particularly pronounced at λ ~ 70 μm. Here we present new simulations that show that this connection is qualitatively robust to a range of parameters: the mass distribution of the giant planets, the width and mass distribution of the outer planetesimal disk, and the presence of gas in the disk when the giant planets become unstable. We discuss how variations in these parameters affect the evolution. We find that systems with equal-mass giant planets undergo the most violent instabilities, and that these destroy both terrestrial planets and the outer planetesimal disks that produce debris disks. In contrast, systems with low-mass giant planets efficiently produce both terrestrial planets and debris disks. A large fraction of systems with low-mass (M ≲ 30 M⊕) outermost giant planets have final planetary separations that, scaled to the planets' masses, are as large or larger than the Saturn-Uranus and Uranus-Neptune separations in the solar system. We find that the gaps between these planets are not only dynamically stable to test particles, but are frequently populated by planetesimals. The possibility of planetesimal belts between outer giant planets should be taken into account when interpreting debris disk SEDs. In addition, the presence of ~ Earth-mass "seeds" in outer planetesimal disks causes the disks to radially spread to colder temperatures, and leads to a slow depletion of the outer planetesimal disk from the inside out. We argue that this may explain the very low frequency of >1 Gyr-old solar-type stars with observed 24 μm excesses. Our simulations do not sample the full range of

  1. Field-trip guide to subaqueous volcaniclastic facies in the Ancestral Cascades arc in southern Washington State—The Ohanapecosh Formation and Wildcat Creek beds

    Science.gov (United States)

    Jutzeler, Martin; McPhie, Jocelyn

    2017-06-27

    Partly situated in the idyllic Mount Rainier National Park, this field trip visits exceptional examples of Oligocene subaqueous volcaniclastic successions in continental basins adjacent to the Ancestral Cascades arc. The >800-m-thick Ohanapecosh Formation (32–26 Ma) and the >300-m-thick Wildcat Creek (27 Ma) beds record similar sedimentation processes from various volcanic sources. Both show evidence of below-wave-base deposition, and voluminous accumulation of volcaniclastic facies from subaqueous density currents and suspension settling. Eruption-fed facies include deposits from pyroclastic flows that crossed the shoreline, from tephra fallout over water, and from probable Surtseyan eruptions, whereas re-sedimented facies comprise subaqueous density currents and debris flow deposits.

  2. Instability and the formation of bubbles and the plugs in fluidized beds

    Directory of Open Access Journals (Sweden)

    Piotr Schulz

    2004-01-01

    Full Text Available This is an review paper, particulary concentrate on results not many researches by reason that are explain in the text. We consider stability of disperse, two-phase flow (gas-solid particles or liquid-solid particles linear and non-linear. In particular we discuss the result of Anderson, Sundareson and Jackson (1995 [Anderson K., Sundareson S., Jackson R.: Instabilities and the formation of bubbles in fluidized beds. J. Fluid Mech. 303 (1995, 327-366] that for vertical dispersion flow one- and two-dimensional, they attack problem growing disturbances directly by numerical integration of equations of motion from given initial conditions (using computer Cray C-90. In principle, this would allow authors to explore all aspects of dynamical behaviour of fluidized beds. It is interesting mechanism of periodic plug describing by Anderson et al. and attest by other researchers. Second part of paper is more general, dedicate the problem of linear stability of uniformly fluidized state ("fluidized bed". We make the most important stages of calculations (after to Jackson (2000 [Jackson R.: The Dynamics of Fluidized Particles. Cambridge University Press 2000] and demonstrate that the majority (but not all of fluidized beds with parameters having technical importance is unstable, or stable in narrow interval of wave numbers \\(k\\.

  3. Tracing the contribution of debris flow-dominated channels to gravel-bed torrential river channel: implementing pit-tags in the upper Guil River (French Alps)

    Science.gov (United States)

    Arnaud-Fassetta, Gilles; Lissak, Candide; Fort, Monique; Bétard, François; Carlier, Benoit; Cossart, Etienne; Madelin, Malika; Viel, Vincent; Charnay, Bérengère; Bletterie, Xavier

    2014-05-01

    Morel (20 pit-tags), Bouchouse (40 pit-tags), Peyronnelle (100 pit-tags). All pit-tags were installed high upstream enough in each catchment to avoid their loss and/or burying, and permit their monitoring over several years. The grain size (D50 = 30-220 cm) of the selected blocks reflects the average size of the bed load. Smaller blocks were discarded to avoid losing their track from the first event. The blocks were positioned according to two logics: (i) Longitudinally, we implemented every 20-30 m a series of nested blocks into the channel; (ii) Transversally, we selected blocks placed in low and high position to quantify the transport dynamics during events of low (torrential) and high (debris flow) magnitude. The sites were mapped at high resolution, and blocks were spotted thanks to fluorescent painting, GPS surveys and detailed photographs. We emplaced the pit-tags in September 2013, before expected avalanches and debris flows during winter and spring 2014. Pit-tags detection, Lidar and photogrammetric surveys are planned for early summer 2014, during which we expect quantifying movement, distance and sorting of blocks along the thalwegs during "ordinary" snowmelt runoff. We intend to continue this monitoring long enough to put observed current and future dynamics in relation to short-term climatic changes.

  4. Experimental investigation of particulate debris spreading in a pool

    Energy Technology Data Exchange (ETDEWEB)

    Konovalenko, A., E-mail: kono@kth.se [Division of Nuclear Power Safety, Royal Institute of Technology (KTH) , Roslagstullsbacken 21, Stockholm 106 91 (Sweden); Basso, S., E-mail: simoneb@kth.se [Division of Nuclear Power Safety, Royal Institute of Technology (KTH) , Roslagstullsbacken 21, Stockholm 106 91 (Sweden); Kudinov, P., E-mail: pkudinov@kth.se [Division of Nuclear Power Safety, Royal Institute of Technology (KTH) , Roslagstullsbacken 21, Stockholm 106 91 (Sweden); Yakush, S.E., E-mail: yakush@ipmnet.ru [Institute for Problems in Mechanics of the Russian Academy of Sciences, Ave. Vernadskogo 101 Bldg 1, Moscow 119526 (Russian Federation)

    2016-02-15

    Termination of severe accident progression by core debris cooling in a deep pool of water under reactor vessel is considered in several designs of light water reactors. However, success of this accident mitigation strategy is contingent upon the effectiveness of heat removal by natural circulation from the debris bed. It is assumed that a porous bed will be formed in the pool in the process of core melt fragmentation and quenching. Debris bed coolability depends on its properties and system conditions. The properties of the bed, including its geometry are the outcomes of the debris bed formation process. Spreading of the debris particles in the pool by two-phase turbulent flows induced by the heat generated in the bed can affect the shape of the bed and thus influence its coolability. The goal of this work is to provide experimental data on spreading of solid particles in the pool by large-scale two-phase flow. The aim is to provide data necessary for understanding of separate effects and for development and validation of models and codes. Validated codes can be then used for prediction of debris bed formation under prototypic severe accident conditions. In PDS-P (Particulate Debris Spreading in the Pool) experiments, air injection at the bottom of the test section is employed as a means to create large-scale flow in the pool in isothermal conditions. The test section is a rectangular tank with a 2D slice geometry, it has fixed width (72 mm), adjustable length (up to 1.5 m) and allows water filling to the depth of up to 1 m. Variable pool length and depth allows studying two-phase circulating flows of different characteristic sizes and patterns. The average void fraction in the pool is determined by video recording and subsequent image processing. Particles are supplied from the top of the facility above the water surface. Results of several series of PDS-P experiments are reported in this paper. The influence of the gas flow rate, pool dimensions, particle density

  5. Formation of accessory mineral bed layers during erosion of bentonite buffer material

    International Nuclear Information System (INIS)

    Schatz, Timothy; Kanerva, Noora

    2012-01-01

    Document available in extended abstract form only. dilute groundwater at a transmissive fracture interface, accessory phases within bentonite, such as quartz, feldspar, etc., might remain behind and form a filter bed or cake. As more and more montmorillonite is lost, the thickness of the accessory mineral bed increases and the continued transport of montmorillonite slows and possibly stops if the porosity of the filter bed is sufficiently compressed. Alternatively or concurrently, as the accessory mineral filter bed retains montmorillonite colloids, a filter cake composed of montmorillonite itself may be formed. Ultimately, depending on their extent, properties, and durability, such processes may provide the bentonite buffer system with an inherent, self-filtration mechanism which serves to limit the effects of colloidal erosion. A conceptual view of bentonite buffer extrusion and erosion in an intersecting fracture with formation of an accessory mineral filter bed and montmorillonite filter cake is presented in Figure 1. Due to the swelling pressure of the bentonite buffer, the situation described in Figure 1 may be analogous to that of the case of pressure filtration where a filter cake is formed by pressing a suspension through a filter medium and, by a mechanism known as expression, the filter cake is compressed by direct contact with a solid surface resulting in a reduction of its porosity. In order to examine whether the erosion of bentonite material through contact with dilute groundwater at a transmissive fracture interface could intrinsically result in 1) the formation of an accessory mineral filter bed and cake and/or 2) filter caking of montmorillonite itself, a series of laboratory tests were performed in a flow-through, horizontal, 1 mm aperture, artificial fracture system. Bentonite buffer material was simulated by using mixtures (75/25 weight percent ratio) of purified sodium montmorillonite and various additives serving as accessory mineral proxies

  6. Environmental characterization of bedded salt formations and overlying areas of the Permian Basin

    International Nuclear Information System (INIS)

    1983-07-01

    This report constitutes one input to the first stage of site qualification studies. It presents a general environmental characterization of the region that is underlain by the Permian bedded salt formation. The formation covers portions of Colorado, Kansas, New Mexico, Oklahoma, and Texas. The Permian bedded salt formation is one of a number of deep, stable geologic formations being studied for potential locations for nuclear waste repositories. These studies will not necessarily lead to selection of a site. They are intended only to provide information necessary to evaluate the suitability of locations for repositories. The report is intended as a general characterization of the existing environmental setting of the Permian Region with emphasis on land, water, and air characteristics; resources; plant and animal life; and man's organizations and activities. The report provides background information about the role that this regional study will play in the overall plan for environmental impact assessments and statements deemed necessary as input to the decision-making process. Background information on the present concept of nuclear waste repository design and function is also included. The information presented in this report has been summarized from open literature readily accessible to the public. No field work was conducted nor new data used in developing the descriptions contained herein

  7. Origin of uraniferous phosphate beds in Wilkins Peak member of Green River Formation, Wyoming

    International Nuclear Information System (INIS)

    Mott, L.V.; Drever, J.I.

    1983-01-01

    The distribution of uranium and phosphorus was studied in four drill cores from the Wilkins Peak Member of the Green River Formation in Wyoming. Of the studied occurrences of anomalously high uranium concentrations, 13% were associated with localized organic matter, and the remainder were associated with stratiform phosphate-rich beds. The uranium probably substitutes for calcium in apatite in these beds. It is proposed that the apatite forms by replacement of calcite during times of flooding of the normally highly saline lake. The flood waters bring in phosphorus and cause a decrease in both pH and ratio of bicarbonate to phosphate, which favors the replacement. Uranium is incorporated in the apatite as the apatite forms or soon after. No special source, other than weathering of volcanic ash, is required for the phosphorus or the uranium. The uraniferous phosphatic beds do not appear to have any economic potential at the present time. Misleadingly high concentrations of both uranium and phosphorus are observed in outcrop samples as a result of selective leaching of other components

  8. Formation and removal of biomass-derived contaminants in fluidized-bed gasification processes

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    The objectives of this thesis were to examine the effects of the feedstock and the operating conditions of a fluidized-bed gasifier on the formation of tars and nitrogen-containing compounds and to study the effectiveness of the hot gas cleaning methods developed for the removal of particulates, alkali metals, tars and nitrogen-containing compounds. The most essential part of the work was carried out in the pressurized fluidized-bed gasification test facilities composed of an air-blown bubbling fluidized-bed gasifier and subsequent hot gas filter unit. The operation pressure of the test rig could be varied in the range 0.3 - 1.0 MPa and the maximum allowable gasification temperature was 1 050 deg C. The maximum capacity with biomass fuels was 80 kg/h. A wide range of feedstocks from hard coals, lignite and peat to different wood derived fuels and straw were used in the gasification tests. Two different types of ceramic filters were tested in the filter unit connected to the pressurized fluidized-bed gasifier. The filter unit was operated in a temperature range of 400 - 740 deg C. The particulate removal requirements set by the gas turbines were met by both types of filters and with product gases derived from all the feedstocks tested. In addition to the gasification and gas filtration tests, catalytic tar and ammonia decomposition was studied using both laboratory and bench-scale test facilities. Inexpensive calcium-based bulk materials, dolomites and limestones, were efficient tar decomposition catalysts in atmospheric-pressure tests

  9. Formation and removal of biomass-derived contaminants in fluidized-bed gasification processes

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1996-12-31

    The objectives of this thesis were to examine the effects of the feedstock and the operating conditions of a fluidized-bed gasifier on the formation of tars and nitrogen-containing compounds and to study the effectiveness of the hot gas cleaning methods developed for the removal of particulates, alkali metals, tars and nitrogen-containing compounds. The most essential part of the work was carried out in the pressurized fluidized-bed gasification test facilities composed of an air-blown bubbling fluidized-bed gasifier and subsequent hot gas filter unit. The operation pressure of the test rig could be varied in the range 0.3 - 1.0 MPa and the maximum allowable gasification temperature was 1 050 deg C. The maximum capacity with biomass fuels was 80 kg/h. A wide range of feedstocks from hard coals, lignite and peat to different wood derived fuels and straw were used in the gasification tests. Two different types of ceramic filters were tested in the filter unit connected to the pressurized fluidized-bed gasifier. The filter unit was operated in a temperature range of 400 - 740 deg C. The particulate removal requirements set by the gas turbines were met by both types of filters and with product gases derived from all the feedstocks tested. In addition to the gasification and gas filtration tests, catalytic tar and ammonia decomposition was studied using both laboratory and bench-scale test facilities. Inexpensive calcium-based bulk materials, dolomites and limestones, were efficient tar decomposition catalysts in atmospheric-pressure tests

  10. Universal stability curve for pattern formation in pulsed gas-solid fluidized beds of sandlike particles

    Science.gov (United States)

    de Martín, Lilian; Ottevanger, Coen; van Ommen, J. Ruud; Coppens, Marc-Olivier

    2018-03-01

    A granular layer can form regular patterns, such as squares, stripes, and hexagons, when it is fluidized with a pulsating gas flow. These structures are reminiscent of the well-known patterns found in granular layers excited through vibration, but, contrarily to them, they have been hardly explored since they were first discovered. In this work, we investigate experimentally the conditions leading to pattern formation in pulsed fluidized beds and the dimensionless numbers governing the phenomenon. We show that the onset to the instability is universal for Geldart B (sandlike) particles and governed by the hydrodynamical parameters Γ =ua/(utϕ ¯) and f /fn , where ua and f are the amplitude and frequency of the gas velocity, respectively, ut is the terminal velocity of the particles, ϕ ¯ is the average solids fraction, and fn is the natural frequency of the bed. These findings suggest that patterns emerge as a result of a parametric resonance between the kinematic waves originating from the oscillating gas flow and the bulk dynamics. Particle friction plays virtually no role in the onset to pattern formation, but it is fundamental for pattern selection and stabilization.

  11. Shell Bed Identification of Kaliwangu Formation and its Sedimentary Cycle Significance, Sumedang, West Java

    Directory of Open Access Journals (Sweden)

    Aswan Aswan

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i1.151Kaliwangu Formation cropping out around Sumedang area contains mollusk fossils dominated by gastropods and bivalves. In terms of sequence stratigraphy, each sedimentary cycle generally consists of four shell bed types: Early Transgressive Systems Tract (Early TST deposited above an erosional surface or sequence boundary, that is characterized by shell disarticulation, trace fossils, gravelly content, no fossil orientation direction, and concretion at the bottom; Late Transgressive Systems Tract (Late TST identified by articulated (conjoined specimen in its life position, that shows a low level abration and fragmentation, adult specimen with complete shells, and variation of taxa; Early Highstand Systems Tract (Early HST characterized by adult taxa that was found locally in their life position with individual articulation, juvenile specimens frequently occured; Late Highstand Systems Tract (Late HST determined as multiple-event concentrations, disarticulated shell domination, and some carbon or amber intercalation indicating terrestrial influence. Shell bed identification done on this rock unit identified nineteen sedimentary cycles.

  12. The formation of impurities in fluidized-bed gasification of biomass, peat and coal; Epaepuhtauksien muodostuminen leijukerroskaasutuksessa

    Energy Technology Data Exchange (ETDEWEB)

    Kurkela, E.; Laatikainen-Luntama, J.; Kurkela, M.; Leppaelahti, J.; Koljonen, T.; Oesch, P. [VTT Energy, Espoo (Finland); Alen, R. [Jyvaeskylae Univ. (Finland)

    1996-12-01

    The objective of this three-year-long project was to study the effects of different process parameters and bed materials on the formation of impurities in pressurized fluidized-bed gasification. The main emphasis of the project was focused on the formation of tars and nitrogen compounds in wood, peat and coal gasification. The aims of the research were to find out such operating conditions, where the formation of problematic high-molecular-weight tars can be minimised and to create a better understanding on the fate of fuel nitrogen in fluidized-bed gasifiers. Main part of the research was carried out in a bench-scale pressurised fluidized-bed reactor (ID 30 mm), where the effects of pressure, temperature, gas atmosphere and bed material were studied with different feedstocks. Most of the test series were carried out using the same feedstocks as earlier used in the PDU-scale fluidized-bed gasification tests of VTT (pine wood, pine bark, wheat straw, two peats, Rhenish brown coal, Polish and Illinois No.6 bituminous coals). The effects of operating parameters on the product yields (gas components, tars, char) were first studied under inert nitrogen atmosphere. The conversion of fuel nitrogen into ammonia and HCN were also determined for the different feedstocks over the different operating conditions. These studies showed that ammonia is the main fixed nitrogen compound of fluidized-bed pyrolysis with all the feedstocks studied. The conversions of fuel nitrogen into ammonia and HCN was highest with the high volatile fuels and lowest with the two hard coals. Gas atmosphere had a dramatic effect on the conversion of fuel nitrogen; much higher ammonia yields were determined in real gasification gas atmosphere than in inert pyrolysis carried out in N{sub 2} or Argon atmosphere. In addition to the pressurised fluidized-bed pyrolysis tests, laboratory scale pyrolysis research was carried out in order to compare the pyrolysis behaviour of the different feedstocks

  13. CFD analysis of hot spot formation through a fixed bed reactor of Fischer-Tropsch synthesis

    Directory of Open Access Journals (Sweden)

    Hamed Aligolzadeh

    2015-12-01

    Full Text Available One of the interesting methods for conversion of synthesis gas to heavy hydrocarbons is Fischer–Tropsch process. The process has some bottlenecks, such as hot spot formation and low degree of conversion. In this work, computational fluid dynamics technique was used to simulate conversion of synthetic gas and product distribution. Also, hot spot formation in the catalytic fixed-bed reactor was investigated in several runs. Simulation results indicated that hot spot formation occurred more likely in the early and middle part of reactor due to high reaction rates. Based on the simulation results, the temperature of hot spots increased with increase in the inlet temperature as well as pressure. Among the many CFD runs conducted, it is found that the optimal temperature and pressure for Fischer–Tropsch synthesis are 565 K and 20 bar, respectively. As it seems that the reactor shall work very well under optimal conditions, the reaction rates and catalyst duration would simultaneously be maximum .

  14. Simulation of the arrival and evolution of debris in a PWR lower head with the SFD ICARE2 code

    International Nuclear Information System (INIS)

    Fichot, F.; Babik, F.; Zabiego, M.; Barrachin, M.; Chatelard, P.; Lefevre, B.

    1999-01-01

    In a severe accident scenario, the prediction of vessel failure is related to the prediction of the behaviour of solid and liquid debris which have fallen into the lower plenum. One of the difficulties is to define the initial debris bed conditions. They will depend on the presence of water or not in the lower plenum. They will also depend on the rate and composition of the falling debris. In this context, IPSN performs calculations using the ICARE2 code in order to predict the core degradation in a scenario similar to TMI-2, and to estimate the so-called initial conditions of the debris bed, i.e. the history of the debris falling into the lower plenum and the evolution of this debris bed. The latest version of ICARE2 (V3mod0) which deals with molten pools and debris bed allows to follow the materials from their early melting in the core region to their later relocation into the lower plenum. A description of the modeling of the debris bed and molten pool formation is provided in this paper. The debris bed modeling is based on a porous medium approach. Mass and energy conservation equations for each of the three phases and momentum conservation equations for the liquid and gas phases are solved. Up to now, due to the lack of knowledge, no model has been developed to estimate the debris size distribution. It is chosen by the user at the beginning of the calculation. As the temperature increases in the debris bed, a molten pool appears and starts to grow. Thermal effects of the natural convection movements in the pool are taken into account using classical correlations. The present study corresponds to a first application of the new capabilities of ICARE2. However it shows the interest of such an approach for a problem where the behaviour in the vessel is closely related to the previous events that occurred in the core region. Improvements are foreseen, especially for the natural convection, crust formation and interaction with water. (authors)

  15. Analysis of orientation patterns in Olduvai Bed I assemblages using GIS techniques: implications for site formation processes.

    Science.gov (United States)

    Benito-Calvo, Alfonso; de la Torre, Ignacio

    2011-07-01

    Mary Leakey's excavations at Olduvai Beds I and II provided an unparalleled wealth of data on the archaeology of the early Pleistocene. We have been able to obtain axial orientations of the Bed I bone and stone tools by applying GIS methods to the site plans contained in the Olduvai Volume 3 monograph (Leakey, 1971). Our analysis indicates that the Bed I assemblages show preferred orientations, probably caused by natural agents such as water disturbance. These results, based on new GIS techniques applied to paleoanthropological studies, have important implications for the understanding of the formative agents of Olduvai sites and the behavioral meaning of the bone and lithic accumulations in Bed I. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. 2D model for melt progression through rods and debris

    International Nuclear Information System (INIS)

    Fichot, F.

    2001-01-01

    During the degradation of a nuclear core in a severe accident scenario, the high temperatures reached lead to the melting of materials. The formation of liquid mixtures at various elevations is followed by the flow of molten materials through the core. Liquid mixture may flow under several configurations: axial relocation along the rods, horizontal motion over a plane surface such as the core support plate or a blockage of material, 2D relocation through a debris bed, etc.. The two-dimensional relocation of molten material through a porous debris bed, implemented for the simulation of late degradation phases, has opened a new way to the elaboration of the relocation model for the flow of liquid mixture along the rods. It is based on a volume averaging method, where wall friction and capillary effects are taken into account by introducing effective coefficients to characterize the solid matrix (rods, grids, debris, etc.). A local description of the liquid flow is necessary to derive the effective coefficients. Heat transfers are modelled in a similar way. The derivation of the conservation equations for the liquid mixture falling flow (momentum) in two directions (axial and radial-horizontal) and for the heat exchanges (energy) are the main points of this new model for simulating melt progression. In this presentation, the full model for the relocation and solidification of liquid materials through a rod bundle or a debris bed is described. It is implemented in the ICARE/CATHARE code, developed by IPSN in Cadarache. The main improvements and advantages of the new model are: A single formulation for liquid mixture relocation, in 2D, either through a rod bundle or a porous debris bed, Extensions to complex structures (grids, by-pass, etc..), The modeling of relocation of a liquid mixture over plane surfaces. (author)

  17. Formation of N{sub 2} during the fixed-bed pyrolysis of coals

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhiheng; Ohtsuka, Yasuo [Tohoku Univ., Sendai (Japan); Furimsky, E. [Natural Resources Canada, Ottawa, Ontario (Canada)

    1995-12-31

    Research on the fate of the nitrogen in coal during pyrolysis has attracted increased attention, since it is related with the NO{sub x} and N{sub 2}O emissions during subsequent combustion. It has been reported that coal nitrogen is initially released as tar, which is then converted to HCN and NH{sub 3} through secondary decomposition reactions. However, little attention to N{sub 2} has been paid so far. We have recently found that N{sub 2} is the dominant product in slow heating rate pyrolysis of a subbituminous coal, and that the finely dispersed iron catalyst promotes drastically the formation of N{sub 2} from a brown coal. If coal nitrogen can be removed efficiently as N{sub 2} during pyrolysis, this method would contribute to the reduction of the NO{sub x} and N{sub 2}O emissions, since such pollutants originate mostly from coal nitrogen. Therefore the present study aims at making clear the influence of coal type, pyrolysis conditions, demineralization, and iron catalyst on the formation of N{sub 2} during the fix-bed pyrolysis of several coals with different ranks.

  18. Hydrous mineral dehydration around heat-generating nuclear waste in bedded salt formations.

    Science.gov (United States)

    Jordan, Amy B; Boukhalfa, Hakim; Caporuscio, Florie A; Robinson, Bruce A; Stauffer, Philip H

    2015-06-02

    Heat-generating nuclear waste disposal in bedded salt during the first two years after waste emplacement is explored using numerical simulations tied to experiments of hydrous mineral dehydration. Heating impure salt samples to temperatures of 265 °C can release over 20% by mass of hydrous minerals as water. Three steps in a series of dehydration reactions are measured (65, 110, and 265 °C), and water loss associated with each step is averaged from experimental data into a water source model. Simulations using this dehydration model are used to predict temperature, moisture, and porosity after heating by 750-W waste canisters, assuming hydrous mineral mass fractions from 0 to 10%. The formation of a three-phase heat pipe (with counter-circulation of vapor and brine) occurs as water vapor is driven away from the heat source, condenses, and flows back toward the heat source, leading to changes in porosity, permeability, temperature, saturation, and thermal conductivity of the backfill salt surrounding the waste canisters. Heat pipe formation depends on temperature, moisture availability, and mobility. In certain cases, dehydration of hydrous minerals provides sufficient extra moisture to push the system into a sustained heat pipe, where simulations neglecting this process do not.

  19. Modeling wood dynamics, jam formation, and sediment storage in a gravel-bed stream

    Science.gov (United States)

    Eaton, B. C.; Hassan, M. A.; Davidson, S. L.

    2012-12-01

    In small and intermediate sized streams, the interaction between wood and bed material transport often determines the nature of the physical habitat, which in turn influences the health of the stream's ecosystem. We present a stochastic model that can be used to simulate the effects on physical habitat of forest fires, climate change, and other environmental disturbances that alter wood recruitment. The model predicts large wood (LW) loads in a stream as well as the volume of sediment stored by the wood; while it is parameterized to describe gravel bed streams similar to a well-studied field prototype, Fishtrap Creek, British Columbia, it can be calibrated to other systems as well. In the model, LW pieces are produced and modified over time as a result of random tree-fall, LW breakage, LW movement, and piece interaction to form LW jams. Each LW piece traps a portion of the annual bed material transport entering the reach and releases the stored sediment when the LW piece is entrained and moved. The equations governing sediment storage are based on a set of flume experiments also scaled to the field prototype. The model predicts wood loads ranging from 70 m3/ha to more than 300 m3/ha, with a mean value of 178 m3/ha: both the range and the mean value are consistent with field data from streams with similar riparian forest types and climate. The model also predicts an LW jam spacing that is consistent with field data. Furthermore, our modeling results demonstrate that the high spatial and temporal variability in sediment storage, sediment transport, and channel morphology associated with LW-dominated streams occurs only when LW pieces interact and form jams. Model runs that do not include jam formation are much less variable. These results suggest that river restoration efforts using engineered LW pieces that are fixed in place and not permitted to interact will be less successful at restoring the geomorphic processes responsible for producing diverse, productive

  20. NOx formation and selective non-catalytic reduction (SNCR) in a fluidized bed combustor of biomass

    International Nuclear Information System (INIS)

    Mahmoudi, Shiva; Baeyens, Jan; Seville, Jonathan P.K.

    2010-01-01

    Caledonian Paper (CaPa) is a major paper mill, located in Ayr, Scotland. For its steam supply, it previously relied on the use of a Circulating Fluidized Bed Combustor (CFBC) of 58 MW th , burning coal, wood bark and wastewater treatment sludge. It currently uses a bubbling fluidized bed combustor (BFBC) of 102 MW th to generate steam at 99 bar, superheated to 465 o C. The boiler is followed by steam turbines and a 15 kg/s steam circuit into the mill. Whereas previously coal, wood bark and wastewater treatment sludge were used as fuel, currently only plantation wood (mainly spruce), demolition wood, wood bark and sludge are used. Since these biosolids contain nitrogen, fuel NO x is formed at the combustion temperature of 850-900 o C. NO x emissions (NO + NO 2 ) vary on average between 300 and 600 mg/Nm 3 (dry gas). The current emission standard is 350 mg/Nm 3 but will be reduced in the future to a maximum of 233 mg/Nm 3 for stand-alone biomass combustors of capacity between 50 and 300 MW th according to the EU LCP standards. NO x abatement is therefore necessary. In the present paper we firstly review the NO x formation mechanisms, proving that for applications of fluidized bed combustion, fuel NO x is the main consideration, and the contribution of thermal NO x to the emissions insignificant. We then assess the deNO x techniques presented in the literature, with an updated review and special focus upon the techniques that are applicable at CaPa. From these techniques, Selective Non-catalytic Reduction (SNCR) using ammonia or urea emerges as the most appropriate NO x abatement solution. Although SNCR deNO x is a selective reduction, the reactions of NO x reduction by NH 3 in the presence of oxygen, and the oxidation of NH 3 proceed competitively. Both reactions were therefore studied in a lab-scale reactor and the results were transformed into design equations starting from the respective reaction kinetics. An overall deNO x yield can then be predicted for any

  1. SO3 Formation and the Effect of Fly Ash in a Bubbling Fluidised Bed under Oxy-Fuel Combustion Conditions.

    Czech Academy of Sciences Publication Activity Database

    Sarbassov, Y.; Duan, L.; Jeremiáš, Michal; Manovic, V.; Anthony, E.J.

    2017-01-01

    Roč. 167, DEC 1 (2017), s. 314-321 ISSN 0378-3820 Institutional support: RVO:67985858 Keywords : SO3 formation * oxy-fuel combustion * fluidised bed Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use OBOR OECD: Energy and fuels Impact factor: 3.752, year: 2016

  2. SO3 Formation and the Effect of Fly Ash in a Bubbling Fluidised Bed under Oxy-Fuel Combustion Conditions.

    Czech Academy of Sciences Publication Activity Database

    Sarbassov, Y.; Duan, L.; Jeremiáš, Michal; Manovic, V.; Anthony, E.J.

    2017-01-01

    Roč. 167, DEC 1 (2017), s. 314-321 ISSN 0378-3820 Institutional support: RVO:67985858 Keywords : SO3 formation * oxy- fuel combustion * fluidised bed Subject RIV: JE - Non-nuclear Energetics, Energy Consumption ; Use OBOR OECD: Energy and fuel s Impact factor: 3.752, year: 2016

  3. TMI-2 core debris analysis

    International Nuclear Information System (INIS)

    Cook, B.A.; Carlson, E.R.

    1985-01-01

    One of the ongoing examination tasks for the damaged TMI-2 reactor is analysis of samples of debris obtained from the debris bed presently at the top of the core. This paper summarizes the results reported in the TMI-2 Core Debris Grab Sample Examination and Analysis Report, which will be available early in 1986. The sampling and analysis procedures are presented, and information is provided on the key results as they relate to the present core condition, peak temperatures during the transient, temperature history, chemical interactions, and core relocation. The results are then summarized

  4. Distal alluvial fan sediments in early Proterozoic red beds of the Wilgerivier formation, Waterberg Group, South Africa

    Science.gov (United States)

    Van Der Neut, M.; Eriksson, P. G.; Callaghan, C. C.

    The 1900 - 1700 M.a. Waterberg Group belongs to a series of southern African cratonic cover sequences of roughly equivalent age. Red beds of the Wilgerivier Formation comprise sandstones, interbedded with subordinate conglomerates and minor mudrocks. These immature sedimentary rocks exhibit lenticular bedding, radial palaeocurrent patterns and features indicative of both streamflow and gravity-flow deposition. A distal wet alluvial fan palaeoenvironmental setting is envisaged, with fan-deltas forming where alluvial lobes prograded into a lacustrine basin. Intrastratal, diagenetic alteration of ferromagnesian detrital grains and ferruginous grain coatings led to the red colouration of the Wilgerivier sediments.

  5. Computer simulation of an internally pressurized radioactive waste disposal room in a bedded salt formation

    International Nuclear Information System (INIS)

    Brown, W.T.; Weatherby, J.R.

    1991-01-01

    The Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico was created by the U.S. Department of Energy as an underground research and development facility to demonstrate the safe storage of transuranic waste generated from defense activities. This facility consists of storage rooms mined from a bedded salt formation at a depth of about 650 meters. Each room will accommodate about 6800 55-gallon drums filled with waste. After waste containers are emplaced, the storage rooms are to be backfilled with mined salt or other backfill materials. As time passes, reconsolidation of this backfill will reduce the hydraulic conductivity of the room. However, gases produced by decomposition and corrosion of waste and waste containers may cause a slow build-up of pressure which can retard consolidation of the waste and backfilled salt. The authors have developed a finite-element model of an idealized disposal room which is assumed to be perfectly sealed. The assumption that no gas escapes from the disposal room is a highly idealized and extreme condition which does not account for leakage paths, such as interbeds, that exist in the surrounding salt formation. This model has been used in a parametric study to determine how reconsolidation is influenced by various assumed gas generation rates and total amounts of gas generated. Results show that reductions in the gas generation, relative to the baseline case, can increase the degree of consolidation and reduce the peak gas pressure in disposal rooms. Even higher degrees of reconsolidation can be achieved by reducing both amounts and rates of gas generation. 8 refs., 4 figs., 1 tab

  6. Woody debris

    Science.gov (United States)

    Donna B. Scheungrab; Carl C. Trettin; Russ Lea; Martin F. Jurgensen

    2000-01-01

    Woody debris can be defined as any dead, woody plant material, including logs, branches, standing dead trees, and root wads. Woody debris is an important part of forest and stream ecosystems because it has a role in carbon budgets and nutrient cycling, is a source of energy for aquatic ecosystems, provides habitat for terrestrial and aquatic organisms, and contributes...

  7. Monte Carlo simulation on influence of cutting beds on density log in the horizontal wells

    International Nuclear Information System (INIS)

    Yu Huawei; Sun Jianmeng; Li Xiaopeng; Zhang Qiongyao; Li Na

    2009-01-01

    Cuttings debris may be deposited in the bottom of a horizontal hole because of gravity of the earth. It has lower density than the formation, so cuttings beds can have a significant effect on the density log responses. Monte Carlo method was used to study the effect of cuttings bed on the computed log density, with various formation densities and cuttings bed thicknesses of 0-5 cm in the horizontal borehole.In order to guarantee the reliability of results, simulation results were compared to the experimental data. MC simulations show that the density measurement can be corrected using the ridge-rib graph, if the thickness of the cutting bed is less than 2 cm. Otherwise, it is difficulty to correct the effect of the cutting bed on the formation density measurement. Finally, the cuttings beds correction charts and formulas for DSDL-8723 double-detector density logging tool which is in the horizontal borehole are made preliminarily. (authors)

  8. Apparatus for controlling molten core debris

    International Nuclear Information System (INIS)

    Golden, M.P.; Tilbrook, R.W.; Heylmun, N.F.

    1972-01-01

    Disclosed is an apparatus for containing, cooling, diluting, dispersing and maintaining subcritical the molten core debris assumed to melt through the bottom of a nuclear reactor pressure vessel in the unlikely event of a core meltdown. The apparatus is basically a sacrificial bed system which includes an inverted conical funnel, a core debris receptacle including a spherical dome, a spherically layered bed of primarily magnesia bricks, a cooling system of zig-zag piping in graphite blocks about and below the bed and a cylindrical liner surrounding the graphite blocks including a steel shell surrounded by firebrick. Tantalum absorber rods are used in the receptacle and bed. 9 claims, 22 figures

  9. Runoff-generated debris flows: observations and modeling of surge initiation, magnitude, and frequency

    Science.gov (United States)

    Kean, Jason W.; McCoy, Scott W.; Tucker, Gregory E.; Staley, Dennis M.; Coe, Jeffrey A.

    2013-01-01

    Runoff during intense rainstorms plays a major role in generating debris flows in many alpine areas and burned steeplands. Yet compared to debris flow initiation from shallow landslides, the mechanics by which runoff generates a debris flow are less understood. To better understand debris flow initiation by surface water runoff, we monitored flow stage and rainfall associated with debris flows in the headwaters of two small catchments: a bedrock-dominated alpine basin in central Colorado (0.06 km2) and a recently burned area in southern California (0.01 km2). We also obtained video footage of debris flow initiation and flow dynamics from three cameras at the Colorado site. Stage observations at both sites display distinct patterns in debris flow surge characteristics relative to rainfall intensity (I). We observe small, quasiperiodic surges at low I; large, quasiperiodic surges at intermediate I; and a single large surge followed by small-amplitude fluctuations about a more steady high flow at high I. Video observations of surge formation lead us to the hypothesis that these flow patterns are controlled by upstream variations in channel slope, in which low-gradient sections act as “sediment capacitors,” temporarily storing incoming bed load transported by water flow and periodically releasing the accumulated sediment as a debris flow surge. To explore this hypothesis, we develop a simple one-dimensional morphodynamic model of a sediment capacitor that consists of a system of coupled equations for water flow, bed load transport, slope stability, and mass flow. This model reproduces the essential patterns in surge magnitude and frequency with rainfall intensity observed at the two field sites and provides a new framework for predicting the runoff threshold for debris flow initiation in a burned or alpine setting.

  10. Formation of early-middle Miocene red beds in the South China Sea: element geochemistry and mineralogy analysis

    Science.gov (United States)

    Lyu, X.; Liu, Z.

    2017-12-01

    The formation of oceanic red beds that usually present oxic and oligotrophic conditions with low sedimentation rate has been used to trace depositional paleoenvironment and paleoclimate change. Red beds overlying oceanic basalts were drilled at two adjacent Sites U1433 and U1434 of IODP Expedition 349 in the Southwest Subbasin of the South China Sea. The occurrence of early-middle Miocene red beds may indicate that at that time there was oxic and quiet marine environment in the deep South China Sea. To understand their formation of red-color, local depositional condition, and potential paleoceanographic significance, major elements (XRF), trace and rare earth elements (ICP-MS), Fe chemical speciation (modified sequential iron extraction procedure), and Fe oxic minerals (CBD and DRS) were analyzed. Geochemical and mineralogical data reveal that hematite and goethite are responsible for the reddish color and red beds were deposited under highly oxic, oligotrophic conditions with a little later hydrothermal influence in the South China Sea. Our results indicate that: (1) after treatment using the CBD procedure, the red samples presented a change in color to greenish, showing the iron oxides being responsible for the sediment color; (2) enriched Mn, depleted U, S enrichment factors, and negative Ce anomaly show that the water mass was pre-oxidized before transported to the study location; (3) low primary productivity was inferred from the lower P, Ba enrichment factors in red beds compared to non-red beds; (4) the excess Mo influx at the bottom may come from the later hydrothermal input; (5) the diverse Ca enrichment factors and correlations between Fe and Al suggest different allogenic sources for red beds at our two sites. We conclude that the red beds at Sites U1433 and U1434 despite their diverse sources both developed in externally oxidized water mass and low primary productivity conditions, and partially altered by hydrothermal fluids after their pelagic

  11. Prediction of corium debris characteristics in lower plenum of a nordic BWR in different accident scenarios using MELCOR code - 15367

    International Nuclear Information System (INIS)

    Phung, V.A.; Galushin, S.; Raub, S.; Goronovski, A.; Villanueva, W.; Koeoep, K; Grishchenko, D.; Kudinov, P.

    2015-01-01

    Severe accident management strategy in Nordic boiling water reactors (BWRs) relies on ex-vessel core debris coolability. The mode of corium melt release from the vessel determines conditions for ex-vessel accident progression and threats to containment integrity, e.g., formation of a non-coolable debris bed and possibility of energetic steam explosion. In-vessel core degradation and relocation is an important stage which determines characteristics of corium debris in the vessel lower plenum, such as mass, composition, thermal properties, timing of relocation, and decay heat. These properties affect debris reheating and remelting, melt interactions with the vessel structures, and possibly vessel failure and melt ejection mode. Core degradation and relocation is contingent upon the accident scenario parameters such as recovery time and capacity of safety systems. The goal of this work is to obtain a better understanding of the impact of the accident scenarios and timing of the events on core relocation phenomena and resulting properties of the debris bed in the vessel lower plenum of Nordic BWRs. In this study, severe accidents in a Nordic BWR reference plant are initiated by a station black out event, which is the main contributor to core damage frequency of the reactor. The work focuses on identifying ranges of debris bed characteristics in the lower plenum as functions of the accident scenario with different recovery timing and capacity of safety systems. The severe accident analysis code MELCOR coupled with GA-IDPSA is used in this work. GA-IDPSA is a Genetic Algorithm-based Integrated Deterministic Probabilistic Safety Analysis tool, which has been developed to search uncertain input parameter space. The search is guided by different target functions. Scenario grouping and clustering approach is applied in order to estimate the ranges of debris characteristics and identify scenario regions of core relocation that can lead to significantly different debris bed

  12. Improving accuracy of overhanging structures for selective laser melting through reliability characterization of single track formation on thick powder beds

    DEFF Research Database (Denmark)

    Mohanty, Sankhya; Hattel, Jesper Henri

    2016-01-01

    Repeatability and reproducibility of parts produced by selective laser melting is a standing issue, and coupled with a lack of standardized quality control presents a major hindrance towards maturing of selective laser melting as an industrial scale process. Consequently, numerical process...... modelling has been adopted towards improving the predictability of the outputs from the selective laser melting process. Establishing the reliability of the process, however, is still a challenge, especially in components having overhanging structures.In this paper, a systematic approach towards...... establishing reliability of overhanging structure production by selective laser melting has been adopted. A calibrated, fast, multiscale thermal model is used to simulate the single track formation on a thick powder bed. Single tracks are manufactured on a thick powder bed using same processing parameters...

  13. Geological and Oceanographic Perspectives on Event Bed Formation during Hurricane Katrina

    National Research Council Canada - National Science Library

    Keen, T. R; Furukawa, Y; Bentley, S. J; Slingerland, R. L; Teague, W. J; Dykes, J. D; Rowley, C. D

    2006-01-01

    .... Using data for tropical cyclone landfalls in the Gulf of Mexico, we estimate the return time for a storm of this size to be 40-50 years in this region. This estimated frequency for deposition of storm beds is useful in evaluating ancient storm sequences that were deposited during similar climatic conditions.

  14. Constraints on the formation and properties of a Martian lobate debris apron: Insights from high-resolution topography, SHARAD radar data, and a numerical ice flow model

    Science.gov (United States)

    Parsons, Reid; Holt, John

    2016-03-01

    Lobate debris aprons (LDAs) are midlatitude deposits of debris-covered ice formed during one or more periods of glaciation during the Amazonian period. However, little is known about the climate conditions that led to LDA formation. We explore a hypothesis in which a single, extended period of precipitation of ice on the steep slopes of Euripus Mons (45°S, 105°E—east of the Hellas Basin) produced a flowing ice deposit which was protected from subsequent ablation to produce the LDA found at this location. We test this hypothesis with a numerical ice flow model using an ice rheology based on low-temperature ice deformation experiments. The model simulates ice accumulation and flow for the northern and southern lobes of the Euripus Mons LDA using basal topography constrained by data from the Shallow Radar (SHARAD) and a range of ice viscosities (determined by ice temperature and ice grain size). Simulations for the northern lobe of the Euripus LDA produce good fits to the surface topography. Assuming an LDA age of ˜60 Myr and an expected temperature range of 200 to 204 K (for various obliquities) gives an ice grain size of ≈2 mm. Simulations of the southern section produce poor fits to surface topography and result in much faster flow timescales unless multiple ice deposition events or higher ice viscosities are considered.

  15. Caldera formation at Volcán Colima, Mexico, by a large large holocene volcanic debris avalanche

    Science.gov (United States)

    Luhr, James F.; Prestegaard, Karen L.

    1988-12-01

    About 4,300 years ago, 10 km 3 of the upper cone of ancestral Volcán Colima collapsed to the southwest leaving a horseshoe-shaped caldera 4 km in diameter. The collapse produced a massive volcanic debris avalanche deposit covering over 1550 km 2 on the southern flanks of the volcano and extending at least 70 km from the former summit. The avalanche followed a steep topographic gradient unobstructed by barriers, resulting in an unusually high area/volume ratio for the Colima deposit. The apparent coefficient of friction (fall height/distance traveled) for the Colima avalanche is 0.06, a low value similar to those of other large-volume deposits. The debris avalanche deposit contains 40-75% angular volcanic clasts from the ancestral cone, a small proportion of vesicular blocks that may be juvenile, and in distal exposures, rare carbonate clasts plucked from the underlying surface by the moving avalanche. Clasts range in size to over 20 m in diameter and are brecciated to different degrees, pulverized, and surrounded by a rock-flour matrix. The upper surface of the deposit shows prominent hummocky topography with closed depressions and surface boulders. A thick, coarse-grained, compositionally zoned scoria-fall layer on the upper northeastern slope of the volcano may have erupted at the time of collapse. A fine-grained surge layer is present beneath the avalanche deposit at one locality, apparently representing an initial blast event. Most of the missing volume of the ancestral volcano has since been restored at an average rate of 0.002 km 3/yr through repeated eruptions from the post-caldera cone. As a result, the southern slope of Volcán Colima may again be susceptible to collapse. Over 200,000 people are now living on primary or secondary deposits of the debris avalanche, and a repetition of this event would constitute a volcanic disaster of great magnitude. Ancestral Volcán Colima grew on the southern, trenchward flank of the earlier and larger volcano Nevado de

  16. Differentiating submarine channel-related thin-bedded turbidite facies: Outcrop examples from the Rosario Formation, Mexico

    Science.gov (United States)

    Hansen, Larissa; Callow, Richard; Kane, Ian; Kneller, Ben

    2017-08-01

    Thin-bedded turbidites deposited by sediment gravity flows that spill from submarine channels often contain significant volumes of sand in laterally continuous beds. These can make up over 50% of the channel-belt fill volume, and can thus form commercially important hydrocarbon reservoirs. Thin-bedded turbidites can be deposited in environments that include levees and depositional terraces, which are distinguished on the basis of their external morphology and internal architecture. Levees have a distinctive wedge shaped morphology, thinning away from the channel, and confine both channels (internal levees) and channel-belts (external levees). Terraces are flat-lying features that are elevated above the active channel within a broad channel-belt. Despite the ubiquity of terraces and levees in modern submarine channel systems, the recognition of these environments in outcrop and in the subsurface is challenging. In this outcrop study of the Upper Cretaceous Rosario Formation (Baja California, Mexico), lateral transects based on multiple logged sections of thin-bedded turbidites reveal systematic differences in sandstone layer thicknesses, sandstone proportion, palaeocurrents, sedimentary structures and ichnology between channel-belt and external levee thin-bedded turbidites. Depositional terrace deposits have a larger standard deviation in sandstone layer thicknesses than external levees because they are topographically lower, and experience a wider range of turbidity current sizes overspilling from different parts of the channel-belt. The thickness of sandstone layers within external levees decreases away from the channel-belt while those in depositional terraces are less laterally variable. Depositional terrace environments of the channel-belt are characterized by high bioturbation intensities, and contain distinctive trace fossil assemblages, often dominated by ichnofabrics of the echinoid trace fossil Scolicia. These assemblages contrast with the lower

  17. Formation of recent martian debris flows by melting of near-surface ground ice at high obliquity.

    Science.gov (United States)

    Costard, F; Forget, F; Mangold, N; Peulvast, J P

    2002-01-04

    The observation of small gullies associated with recent surface runoff on Mars has renewed the question of liquid water stability at the surface of Mars. The gullies could be formed by groundwater seepage from underground aquifers; however, observations of gullies originating from isolated peaks and dune crests question this scenario. We show that these landforms may result from the melting of water ice in the top few meters of the martian subsurface at high obliquity. Our conclusions are based on the analogy between the martian gullies and terrestrial debris flows observed in Greenland and numerical simulations that show that above-freezing temperatures can occur at high obliquities in the near surface of Mars, and that such temperatures are only predicted at latitudes and for slope orientations corresponding to where the gullies have been observed on Mars.

  18. Hybrid simulation of shock formation for super-Alfvénic expansion of laser ablated debris through an ambient, magnetized plasma

    International Nuclear Information System (INIS)

    Clark, S. E.; Schaeffer, D. B.; Everson, E. T.; Bondarenko, A. S.; Constantin, C. G.; Niemann, C.; Winske, D.

    2013-01-01

    Two-dimensional hybrid simulations of perpendicular collisionless shocks are modeled after potential laboratory conditions that are attainable in the LArge Plasma Device (LAPD) at the University of California, Los Angeles Basic Plasma Science Facility. The kJ class 1053 nm Nd:Glass Raptor laser will be used to ablate carbon targets in the LAPD with on-target energies of 100-500 J. The ablated debris ions will expand into ambient, partially ionized hydrogen or helium. A parameter study is performed via hybrid simulation to determine possible conditions that could lead to shock formation in future LAPD experiments. Simulation results are presented along with a comparison to an analytical coupling parameter

  19. Granular fingering as a mechanism for ridge formation in debris avalanche deposits: Laboratory experiments and implications for Tutupaca volcano, Peru

    Science.gov (United States)

    Valderrama, P.; Roche, O.; Samaniego, P.; van Wyk des Vries, B.; Araujo, G.

    2018-01-01

    The origin of subparallel, regularly-spaced longitudinal ridges often observed at the surface of volcanic and other rock avalanche deposits remains unclear. We addressed this issue through analogue laboratory experiments on flows of bi-disperse granular mixtures, because this type of flow is known to exhibit granular fingering that causes elongated structures resembling the ridges observed in nature. We considered four different mixtures of fine (300-400 μm) glass beads and coarse (600-710 μm to 900-1000 μm) angular crushed fruit stones, with particle size ratios of 1.9-2.7 and mass fractions of the coarse component of 5-50 wt%. The coarse particles segregated at the flow surface and accumulated at the front where flow instabilities with a well-defined wavelength grew. These formed granular fingers made of coarse-rich static margins delimiting fines-rich central channels. Coalescence of adjacent finger margins created regular spaced longitudinal ridges, which became topographic highs as finger channels drained at final emplacement stages. Three distinct deposit morphologies were observed: 1) Joined fingers with ridges were formed at low (≤ 1.9) size ratio and moderate (10-20 wt%) coarse fraction whereas 2) separate fingers or 3) poorly developed fingers, forming series of frontal lobes, were created at larger size ratios and/or higher coarse contents. Similar ridges and lobes are observed at the debris avalanche deposits of Tutupaca volcano, Peru, suggesting that the processes operating in the experiments can also occur in nature. This implies that volcanic (and non-volcanic) debris avalanches can behave as granular flows, which has important implications for interpretation of deposits and for modeling. Such behaviour may be acquired as the collapsing material disaggregates and forms a granular mixture composed by a right grain size distribution in which particle segregation can occur. Limited fragmentation and block sliding, or grain size distributions

  20. Effects of 1-week head-down tilt bed rest on bone formation and the calcium endocrine system

    Science.gov (United States)

    Arnaud, Sara B.; Whalen, Robert T.; Fung, Paul; Sherrard, Donald J.; Maloney, Norma

    1992-01-01

    The -6-deg head-down tilt (HDT) is employed in the study of 8 subjects to determine early responses in human bone and calcium endocrines during spaceflight. The average rates of bone formation in the iliac crest are determined by means of a single-dose labeling schedule and are found to decrease in 6 of the subjects. The decrease varies directly with walking miles, and increased excretion of urinary Ca and Na are observed preceding increased levels of ionized serum calcium on a bed-rest day late in the week. Reduced phosphorous excretions are also followed by increased serum phosphorous on day six, and reductions are noted in parathyroid hormone and vitamin D by the end of the experiment. The data demonstrate the responsiveness of the skeletal system to biomechanical stimuli such as the HDT.

  1. JSC Orbital Debris Website Description

    Science.gov (United States)

    Johnson, Nicholas L.

    2006-01-01

    Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as

  2. Methylotrophic methanogenesis governs the biogenic coal bed methane formation in Eastern Ordos Basin, China

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hongguang; Yu, Zhisheng; Liu, Ruyin [Graduate Univ. of Chinese Academy of Sciences, Beijing (China). College of Resources and Environment; Zhang, Hongxun [Graduate Univ. of Chinese Academy of Sciences, Beijing (China). College of Resources and Environment; Chinese Academy of Sciences, Beijing (China). Research Center for Eco-Environmental Sciences; Zhong, Qiding; Xiong, Zhenghe [China National Research Institute of Food and Fermentation Industries, Beijing (China). Food Analysis using Isotope Technology Lab

    2012-12-15

    To identify the methanogenic pathways present in a deep coal bed methane (CBM) reservoir associated with Eastern Ordos Basin in China, a series of geochemical and microbiological studies was performed using gas and water samples produced from the Liulin CBM reservoir. The composition and stable isotopic ratios of CBM implied a mixed biogenic and thermogenic origin of the methane. Archaeal 16S rRNA gene analysis revealed the dominance of the methylotrophic methanogen Methanolobus in the water produced. The high potential of methane production by methylotrophic methanogens was found in the enrichments using the water samples amended with methanol and incubated at 25 and 35 C. Methylotrophic methanogens were the dominant archaea in both enrichments as shown by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Bacterial 16S rRNA gene analysis revealed that fermentative, sulfate-reducing, and nitrate-reducing bacteria inhabiting the water produced were a factor in coal biodegradation to fuel methanogens. These results suggested that past and ongoing biodegradation of coal by methylotrophic methanogens and syntrophic bacteria, as well as thermogenic CBM production, contributed to the Liulin CBM reserves associated with the Eastern Ordos Basin. (orig.)

  3. CFD simulation of ash deposit formation in fixed bed biomass furnaces and boilers

    NARCIS (Netherlands)

    Forstner, M.; Hofmeister, G.; Joeller, M.; Dahl, J.; Braun, M.; Kleditzsch, S.; Scharler, R.; Obernberger, I.

    2006-01-01

    In order to describe and predict the formation of ash deposits in biomass fired combustion plants, a mathematical model is being developed and implemented into the CFD code Fluent¿ as a post processing tool. At the present state of development the model covers the release of coarse ash particles and

  4. Formation of chlorinated organic compounds in fluidized bed combustion of recycled fuels

    International Nuclear Information System (INIS)

    Vesterinen, R.; Kallio, M.; Kirjalainen, T.; Kolsi, A.; Merta, M.

    1997-01-01

    Four tests of co-combustion of recycled fuels (REP) with peat and coal in the 15 kW fluidized bed reactor were performed. The recycled fuel was so-called dry fraction in four vessels sampling at Keltinmaeki. In three tests a part of peat energy was replaced with coal. The mixtures were prepared so that in all mixtures 25 % of energy was recycled fuel and 75 % was either peat or the mixture of peat and coal. The concentrations of polyaromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and chlorophenols decreased with increasing part of coal due to the increasing sulphur/chlorine ratio. Principal Component Analysis (PCA) and Partial Least Square regression analysis (PLS) showed that the chlorine, copper and sulphur contents of the fuel effected most on the concentrations of chlorophenols, chlorobenzenes, PCBs and PCDDs/PCDFs. Other variables influencing on a model were the lead concentration and the sulphur/chlorine ratio in fuel and the hydrogen chloride concentration of the flue gas. The concentrations of chlorophenols and chlorobenzenes were also significant for PCDD/PCDF concentrations in flue gas. The sulphur, chlorine, copper and chromium contents in fly ash and the temperature of the reactor influenced on the chlorophenol, chlorobenzene, PCB and PCDD/PCDF concentrations in fly ash. The chlorophenol and chlorobenzene contents in fly ash, the sulphur/chlorine ratio and the lead content in fuel, the sulphur dioxide, hydrogen chloride and carbon monoxide concentrations in flue gas had also influence on PCDD/PCDF concentrations in fly ash

  5. Geological setting and paleomagnetism of the Eocene red beds of Laguna Brava Formation (Quebrada Santo Domingo, northwestern Argentina)

    Science.gov (United States)

    Vizán, H.; Geuna, S.; Melchor, R.; Bellosi, E. S.; Lagorio, S. L.; Vásquez, C.; Japas, M. S.; Ré, G.; Do Campo, M.

    2013-01-01

    The red bed succession cropping out in the Quebrada Santo Domingo in northwestern Argentina had been for long considered as Upper Triassic-Lower Jurassic in age based on weak radiometric and paleontological evidence. Preliminary paleomagnetic data confirmed the age and opened questions about the nature of fossil footprints with avian features discovered in the section. Recently the stratigraphic scheme was reviewed with the identification of previously unrecognized discontinuities, and a radiometric dating obtained in a tuff, indicated an Eocene age for the Laguna Brava Formation and the fossil bird footprints, much younger than the previously assigned. We present a detailed paleomagnetic study interpreted within a regional tectonic and stratigraphic framework, looking for an explanation for the misinterpretation of the preliminary paleomagnetic data. The characteristic remanent magnetizations pass a tilt test and a reversal test. The main magnetic carrier is interpreted to be low Ti titanomagnetites and to a lesser extent hematite. The characteristic remanent magnetization would be essentially detrital. The obtained paleomagnetic pole (PP) for the Laguna Brava Formation has the following geographic coordinates and statistical parameters: N = 29, Lon. = 184.5° E, Lat. = 75.0° S, A95 = 5.6° and K = 23.7. When this PP is compared with another one with similar age obtained in an undeformed area, a declination anomaly is recognized. This anomaly can be interpreted as Laguna Brava Formation belonging to a structural block that rotated about 16° clockwise along a vertical axis after about 34 Ma. This block rotation is consistent with the regional tectonic framework, and would have caused the fortuitous coincidence of the PP with Early Jurassic poles. According to the interpreted magnetostratigraphic correlation, the Laguna Brava Formation would have been deposited during the Late Eocene with a mean sedimentation rate of about 1.4 cm per thousand years, probably in

  6. Ice Cliff Backwasting over debris-covered Glaciers - Insights into their Formation and Development based on new Measurements and a point-scale Model

    Science.gov (United States)

    Steiner, J. F.; Pellicciotti, F.; Buri, P.; Miles, E. S.; Reid, T. D.; Immerzeel, W.

    2014-12-01

    The presence of ice cliffs has been identified as one possible reason for relatively high overall ablation rates on debris covered glaciers. Few measurements exist for such cliffs and their formation and evolution processes are still poorly understood. On Lirung Glacier, in the Nepalese Himalayas, numerous cliffs were monitored for two consecutive years in the pre- and post-monsoon season. Slope varied between 30° and full vertical faces. Backwasting rates were highly variable depending on slope and aspect of the location on the cliff. Only a physically based energy balance model can reproduce this heterogeneity and provide insights into the importance of atmospheric forcing and cliff characteristics on their melt. Building on two previous studies such a model was developed. It was improved with measurements of radiative fluxes perpendicular to the cliff and by applying a high resolution DEM of the surrounding topography to estimate shading and radiative fluxes incident to the cliff including longwave radiation emitted by surrounding debris. We obtain a considerable reduction in incoming shortwave radiation for north-oriented cliffs compared to horizontal measurements, and significant incident longwave component that varies with height on the cliffs. Melt rates are highly variable in time and space for the cliff. While maximum values of up to 8 cm/day are reached during monsoon, melt rates in the post-monsoon season are considerably lower than in the pre-monsoon season. Nighttime refreezing processes during this period also played an important role. Apart from topography, cliff backwasting is extremely sensitive to albedo of the ice surface, reaching values as low as 0.05. Measurements of surface temperature and wind on the cliff further improved the understanding of outgoing radiation and turbulent fluxes. Once validated against stakes readings, the model was used to explain the presence and persistence of cliffs over Lirung glacier. We show that only North

  7. Flow-sediment-large woody debris interplay: Introducing an appropriately scaled laboratory experiment

    Science.gov (United States)

    Friedrich, H.; Spreitzer, G.; Tunnicliffe, J. F.

    2017-12-01

    The morphology of steep (>0.01 m/m) forested streams is governed not only by water-sediment interplay, but also by accumulations of coarse and fine organic debris. In this project we look at the jamming dynamics (formation, persistence and hydraulic feedbacks) of large woody debris with the help of scaled laboratory experiments. In New Zealand, the recruitment of wood from both natural tree-fall and forest harvesting has led to obstruction of culverts, bridges and other river constrictions. Understanding the dynamics of jam formation and persistence is important for harvest practice guidelines, management of sediment accumulation, as well as establishing impacts to habitat and infrastructure. In this study, we provide the context of our work, present our experimental setup for studying the complex flow-sediment-wood interactions and present some initial results. In our experimental setup, we varied feed rates of sediment and organic fine material in order to establish concentration thresholds for jam formation, and development of sediment retention capacity upstream of the jam. Large woody debris accumulation is studied for different blocking scenarios, and the effect on sediment transport is measured. Sediment quantities and changes in channel bed morphology upstream of the critical cross section are evaluated, together with resulting backwater effects, and associated energy losses. In the long term, our results will inform our understanding of the processes that take place from the mobilization of woody debris to accumulation.

  8. Backwater development by woody debris

    Science.gov (United States)

    Geertsema, Tjitske; Torfs, Paul; Teuling, Ryan; Hoitink, Ton

    2017-04-01

    Placement of woody debris is a common method for increasing ecological values in river and stream restoration, and is thus widely used in natural environments. Water managers, however, are afraid to introduce wood in channels draining agricultural and urban areas. Upstream, it may create backwater, depending on hydrodynamic characteristics including the obstruction ratio, the Froude number and the surface level gradient. Patches of wood may trigger or counter morphological activity, both laterally, through bank erosion and protection, and vertically, with pool and riffle formation. Also, a permeable construction composed of wood will weather over time. Both morphodynamic activity and weathering cause backwater effects to change in time. The purpose of this study is to quantify the time development of backwater effects caused by woody debris. Hourly water levels gauged upstream and downstream of patches and discharge are collected for five streams in the Netherlands. The water level drop over the woody debris patch relates to discharge in the streams. This relation is characterized by an increasing water level difference for an increasing discharge, up to a maximum. If the discharge increases beyond this level, the water level difference reduces to the value that may represent the situation without woody debris. This reduction depends primarily on the obstruction ratio of the woody debris in the channel cross-section. Morphologic adjustments in the stream and reorientation of the woody material reduce the water level drop over the patches in time. Our results demonstrate that backwater effects can be reduced by optimizing the location where woody debris is placed and manipulating the obstruction ratio. Current efforts are focussed on representing woody debris in a one-dimensional numerical model, aiming to obtain a generic tool to achieve a stream design with woody debris that minimizes backwater.

  9. Globular Cluster Formation at High Density: A Model for Elemental Enrichment with Fast Recycling of Massive-star Debris

    Energy Technology Data Exchange (ETDEWEB)

    Elmegreen, Bruce G., E-mail: bge@us.ibm.com [IBM Research Division, T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)

    2017-02-10

    The self-enrichment of massive star clusters by p -processed elements is shown to increase significantly with increasing gas density as a result of enhanced star formation rates and stellar scatterings compared to the lifetime of a massive star. Considering the type of cloud core where a globular cluster (GC) might have formed, we follow the evolution and enrichment of the gas and the time dependence of stellar mass. A key assumption is that interactions between massive stars are important at high density, including interactions between massive stars and massive-star binaries that can shred stellar envelopes. Massive-star interactions should also scatter low-mass stars out of the cluster. Reasonable agreement with the observations is obtained for a cloud-core mass of ∼4 × 10{sup 6} M {sub ⊙} and a density of ∼2 × 10{sup 6} cm{sup −3}. The results depend primarily on a few dimensionless parameters, including, most importantly, the ratio of the gas consumption time to the lifetime of a massive star, which has to be low, ∼10%, and the efficiency of scattering low-mass stars per unit dynamical time, which has to be relatively large, such as a few percent. Also for these conditions, the velocity dispersions of embedded GCs should be comparable to the high gas dispersions of galaxies at that time, so that stellar ejection by multistar interactions could cause low-mass stars to leave a dwarf galaxy host altogether. This could solve the problem of missing first-generation stars in the halos of Fornax and WLM.

  10. On turbulence and the formation of riffle-pools in gravel-bed rivers

    Science.gov (United States)

    MacVicar, Bruce J.

    Cette these doctorale porte sur l'organisation des rivieres a lit de graviers. La formation du lit en sequences a grande echelle---les sequences seuil-mouille---est une caracteristique de ces rivieres qui controle la stabilite et la productivite ecologique. Malgre son importance, le mecanisme qui genere les seuil-mouilles reste obscur. Ce probleme est lie a trois facteurs: les donnees de terrain qui existent ne sont pas suffisantes pour accepter ou rejeter les hypotheses qui existent, la complexite des interactions entre l'ecoulement, le transport des sediments, et les formes du lit; et le role de la turbulence qui n'est pas considere de facon adequate. L'approche de cette these est d'aborder ces facteurs simultanement avec des methodes innovatrices pour mesurer les parametres importants sur le terrain et de modeliser des processus non lineaires dans une riviere. Les objectifs sont: (a) de developper un modele qui est capable de simuler le transport des sediments et les interactions avec l'ecoulement turbulent, (b) en utilisant le modele, de montrer le role des mecanismes de retroaction dans le developpement des formes du lit, (c) de tester les velocimetres dans des ecoulements a fortes vitesses et fortes intensites turbulente, (d) de mesurer et caracteriser les dynamiques de l'ecoulement dans un seuil-mouille force, (e) de mesurer et caracteriser les dynamiques de la sedimentologie et la morphologie dans un seuil-mouille force, et (f) en utilisant le modele et l'analyse des donnees de terrain, d'identifier les mecanismes qui contribuent a la formation des seuils-mouilles. En considerant une riviere comme un systeme complexe, nous avons cree un modele qui simule le transport des sediments individuellement, c'est-a-dire un modele 'discret'. Les particules repondent aux parametres locaux de l'ecoulement et des boucles de retroaction sont possibles. Les processus physiques sont simplifies afin de permettre la consideration des mecanismes qui generent les formes du lit

  11. Cultivation-independent analysis of archaeal and bacterial communities of the formation water in an Indian coal bed to enhance biotransformation of coal into methane

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Durgesh Narain; Kumar, Ashok; Tripathi, Anil Kumar [Banaras Hindu Univ., Varanasi (India). School of Biotechnolgy; Sarbhai, Munish Prasad [Oil and Natural Gas Commission, Ahmedabad (India). Inst. of Reservoir Studies

    2012-02-15

    Biogenic origin of the significant proportion of coal bed methane has indicated the role of microbial communities in methanogenesis. By using cultivation-independent approach, we have analysed the archaeal and bacterial community present in the formation water of an Indian coal bed at 600-700 m depth to understand their role in methanogenesis. Presence of methanogens in the formation water was inferred by epifluorescence microscopy and PCR amplification of mcrA gene. Archaeal 16S rRNA gene clone library from the formation water metagenome was dominated by methanogens showing similarity to Methanobacterium, Methanothermobacter and Methanolinea whereas the clones of bacterial 16S rRNA gene library were closely related to Azonexus, Azospira, Dechloromonas and Thauera. Thus, microbial community of the formation water consisted of predominantly hydrogenotrophic methanogens and the proteobacteria capable of nitrogen fixation, nitrate reduction and polyaromatic compound degradation. Methanogenic potential of the microbial community present in the formation water was elucidated by the production of methane in the enrichment culture, which contained 16S rRNA gene sequences showing close relatedness to the genus Methanobacterium. Microcosm using formation water as medium as well as a source of inoculum and coal as carbon source produced significant amount of methane which increased considerably by the addition of nitrite. The dominance of Diaphorobacter sp. in nitrite amended microcosm indicated their important role in supporting methanogenesis in the coal bed. This is the first study indicating existence of methanogenic and bacterial community in an Indian coal bed that is capable of in situ biotransformation of coal into methane. (orig.)

  12. Debris Flows and Related Phenomena

    Science.gov (United States)

    Ancey, C.

    Torrential floods are a major natural hazard, claiming thousands of lives and millions of dollars in lost property each year in almost all mountain areas on the Earth. After a catastrophic eruption of Mount St. Helen in the USA in May 1980, water from melting snow, torrential rains from the eruption cloud, and water displaced from Spirit Lake mixed with deposited ash and debris to produce very large debris flows and cause extensive damage and loss of life [1]. During the 1985 eruption of Nevado del Ruiz in Colombia, more than 20,000 people perished when a large debris flow triggered by the rapid melting of snow and ice at the volcano summit, swept through the town of Armero [2]. In 1991, the eruption of Pinatubo volcano in the Philippines disperses more than 5 cubic kilometres of volcanic ash into surrounding valleys. Much of that sediment has subsequently been mobilised as debris flows by typhoon rains and has devastated more than 300 square kilometres of agricultural land. Even, in Eur opean countries, recent events that torrential floods may have very destructive effects (Sarno and Quindici in southern Italy in May 1998, where approximately 200 people were killed). The catastrophic character of these floods in mountainous watersheds is a consequence of significant transport of materials associated with water flows. Two limiting flow regimes can be distinguished. Bed load and suspension refer to dilute transport of sediments within water. This means that water is the main agent in the flow dynamics and that the particle concentration does not exceed a few percent. Such flows are typically two-phase flows. In contrast, debris flows are mas s movements of concentrated slurries of water, fine solids, rocks and boulders. As a first approximation, debris flows can be treated as one-phase flows and their flow properties can be studied using classical rheological methods. The study of debris flows is a very exciting albeit immature science, made up of disparate elements

  13. Exotic clasts, debris flow deposits and their significance for reconstruction of the Istebna Formation (Late Cretaceous - Paleocene, Silesian Basin, Outer Carpathians)

    Science.gov (United States)

    Strzeboński, Piotr; Kowal-Kasprzyk, Justyna; Olszewska, Barbara

    2017-08-01

    The different types of calcareous exotic clasts (fragments of pre-existing rocks), embedded in the Paleocene siliciclastic deposits of the Istebna Formation from the Beskid Mały Mountains (Silesian Unit, Western Outer Carpathians), were studied and differentiated through microfacies-biostratigraphical analysis. Calcareous exotics of the Oxfordian- Kimmeridgian age prevail, representing a type of sedimentation comparable to that one documented for the northern Tethyan margin. The Tithonian exotic clasts (Štramberk-type limestones), which are much less common, were formed on a carbonate platform and related slope. The sedimentary paleotransport directions indicate the Silesian Ridge as a main source area for all exotics, which were emplaced in the depositional setting of the flysch deposits. The exotics constitute a relatively rare local component of some debrites. Proceedings of the sedimentological facies analysis indicate that these mass transport deposits were accumulated en-masse by debris flows in a deep-water depositional system in the form of a slope apron. Exotics prove that clasts of the crystalline basement and, less common, fragments of the sedimentary cover, originated from long-lasting tectonic activity and intense uplift of the source area. Mass transport processes and mass accumulation of significant amounts of the coarse-grained detrital material in the south facial zone of the Silesian Basin during the Early Paleogene was due to reactivation of the Silesian Ridge and its increased denudation. Relative regression and erosion of the emerged older flysch deposits were also forced by this uplift. These processes were connected with the renewed diastrophic activity in the Alpine Tethys.

  14. Petrography and geochemistry of selected lignite beds in the Gibbons Creek mine (Manning Formation, Jackson Group, Paleocene) of east-central Texas

    Science.gov (United States)

    Warwick, Peter D.; Crowley, Sharon S.; Ruppert, Leslie F.; Pontolillo, James

    1997-01-01

    This study examined the petrographic and geochemical characteristics of two lignite beds (3500 and 4500 beds, Manning Formation, Jackson Group, Eocene) that are mined at the Gibbons Creek mine in east-central Texas. The purpose of the study was to identify the relations among sample ash yield, coal petrography, and trace-element concentrations in lignite and adjoining rock layers of the Gibbons Creek mine. Particular interest was given to the distribution of 12 environmentally sensitive trace elements (As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, and U) that have been identified as potentially hazardous air pollutants (HAPs) in the United States Clean Air Act Amendments of 1990. Eleven lignite, floor, and rock parting samples were collected from incremental channel samples of the 3500 and 4500 beds that were exposed in a highwall of pit A3 at the Gibbons Creek mine. Short proximate and ultimate and forms of sulfur analyses were performed on all lignite samples, and lignite and rock samples were analyzed for 60 major, minor and trace elements. Representative splits of all lignite samples were ground and cast into pellets, and polished for petrographic analyses in blue-light fluorescence and reflected white light to determine liptinite, inertinite, and huminite maceral group percentages. The following observations summarize our results and conclusions about the geochemistry, petrography, and sedimentology of the 3500 and 4500 beds of the Gibbons Creek lignite deposit: (1) Weighted average dry (db) ash yield for the two beds is 29.7%, average total sulfur content is 2.6%, and average calorific value is 7832 Btu (18.22 MJ/kg). Ash yields are greatest in the lower bench (59.33% db) of the 3500 bed and in the upper bench of the 4500 bed (74.61% db). (2) For lignite samples (on a whole-coal basis), the distributions of two of the HAPs (Pb and Sb) are positively related to ash yield, probably indicating an inorganic affinity for these elements. By using cluster analysis we

  15. Depositional environment and sedimentary of the basinal sediments in the Eibiswalder Bucht (Radl Formation and Lower Eibiswald Beds), Miocene Western Styrian Basin, Austria

    Science.gov (United States)

    Stingl, K.

    1994-12-01

    The Eibiswald Bucht is a small subbasin of the Western Styrian Basin exposing sediments of Lower Miocene age. In the past the entire sequence exposed in the Eibiswalder Bucht has been interpreted as being of fluvial/lacustrine origin; here, results are presented of detailed sedimentological investigations that lead to a revision of this concept. The lowermost siliciclastic sedimentary unit of the Eibiswalder Bucht sequence is the Radl Formation. It is overlain by the Eibiswald Beds, which are subdivided into the Lower, Middle and Upper Eibiswald Beds. The Radl Formation and the Lower Eibiswald Beds are interpreted as a fan delta complex deposited along NNW-SSE striking faults. Based on the sedimentary facies this fan delta can be subdivided into a subaerial alluvial fan facies group, a proximal delta facies group and a distal delta/prodelta facies group. The Radl Formation comprises the alluvial fan and proximal delta facies groups, the Lower Eibiswald Beds the distal delta/prodelta facies group. The alluvial fan and the proximal delta consist of diverse deposits of gravelly flows. The distal delta/prodelta consists of wave-reworked, bioturbated, low density turbidites intercalated with minor gravelly mass flows. The prodelta can be regarded as as the basin facies of the small and shallow Eibiswalder Bucht, where marine conditions prevailed. The basin was probably in part connected with the Eastern Styrian Basin, the contemporary depositional environment of the Styrian Schlier (mainly turbiditic marine offshore sediments in the Eastern Styrian Basin). Analysis of the clast composition, in conjunction with the paleotransport direction of the coarse delta mass flows of the Radl Formation, shows that the source rocks were exclusively crystalline rocks ranging from greenschists to eclogites.

  16. Orbital debris: a technical assessment

    National Research Council Canada - National Science Library

    Committee on Space Debris, National Research Council

    ..., and other debris created as a byproduct of space operations. Orbital Debris examines the methods we can use to characterize orbital debris, estimates the magnitude of the debris population, and assesses the hazard that this population poses to spacecraft...

  17. Experimental study of head loss and filtration for LOCA debris

    International Nuclear Information System (INIS)

    Rao, D.V.; Souto, F.J.

    1996-02-01

    A series of controlled experiments were conducted to obtain head loss and filtration characteristics of debris beds formed of NUKON trademark fibrous fragments, and obtain data to validate the semi-theoretical head loss model developed in NUREG/CR-6224. A thermally insulated closed-loop test set-up was used to conduct experiments using beds formed of fibers only and fibers intermixed with particulate debris. A total of three particulate mixes were used to simulate the particulate debris. The head loss data were obtained for theoretical fiber bed thicknesses of 0.125 inches to 4.0 inches; approach velocities of 0.15 to 1.5 ft/s; temperatures of 75 F and 125 F; and sludge-to-fiber nominal concentration ratios of 0 to 60. Concentration measurements obtained during the first flushing cycle were used to estimate the filtration efficiencies of the debris beds. For test conditions where the beds are fairly uniform, the head loss data were predictable within an acceptable accuracy range by the semi-theoretical model. The model was equally applicable for both pure fiber beds and the mixed beds. Typically the model over-predicted the head losses for very thin beds and for thin beds at high sludge-to-fiber mass ratios. This is attributable to the non-uniformity of such debris beds. In this range the correlation can be interpreted to provide upper bound estimates of head loss. This is pertinent for loss of coolant accidents in boiling water reactors

  18. Autogenic dynamics of debris-flow fans

    Science.gov (United States)

    van den Berg, Wilco; de Haas, Tjalling; Braat, Lisanne; Kleinhans, Maarten

    2015-04-01

    , the debris flows started to channelize, forced by increasingly effective concentration of the flow impulse to the flow front, which caused more effective lateral levee formation and an increasingly well-defined channel. This process continued until the debris flows reached their maximum possible extent and the cycle was reverted. Channelization occurred in the absence of erosion, in contrast with fluvial fans. Backfilling and channelization cycles were gradual and symmetric, requiring multiple debris flows to be completed. These results add debris-flow fans to the spectrum of fan-shaped aqueous systems that are affected by autogenic dynamics, now ranging from low-gradient rivers systems to steep-gradient mass-flow fans.

  19. Bed Bugs

    Science.gov (United States)

    Prevent, identify, and treat bed bug infestations using EPA’s step-by-step guides, based on IPM principles. Find pesticides approved for bed bug control, check out the information clearinghouse, and dispel bed bug myths.

  20. Laser ignition of traumatically embedded firework debris.

    Science.gov (United States)

    Taylor, C R

    1998-01-01

    The Q-switched ruby laser (QSRL) has a good track record for traumatic tattoo removal. An unusual case of QSRL-treatment of a traumatic tattoo composed of firework debris is presented. A young man's traumatic tattoo, composed of firework debris, underwent QSRL ablation at 4-7 J/cm2 (pulse width 5 mm; duration 20 ns). Each test pulse produced visible sparks and focal projectile ejection of skin with pox-like scar formation. Caution is advised when using the QSRL for the treatment of traumatic tattoos composed of potentially combustible debris.

  1. Controlled biomass formation and kinetics of toluene degradation in a bioscrubber and in a reactor with a periodically moved trickle-bed.

    Science.gov (United States)

    Wübker, S M; Laurenzis, A; Werner, U; Friedrich, C

    1997-08-20

    The kinetics of degradation of toluene from a model waste gas and of biomass formation were examined in a bioscrubber operated under different nutrient limitations with a mixed culture. The applicability of the kinetics of continuous cultivation of the mixed culture was examined for a special trickle-bed reactor with a periodically moved filter bed. The efficiency of toluene elimination of the bioscrubber was 50 to 57% and depended on the toluene mass transfer as evident from a constant productivity of 0.026 g dry cell weight/L . h over the dilution rate. Under potassium limitation the biomass productivity was reduced by 60% to 0.011 g dry cell weight/L . h at a dilution rate of 0.013/h. Conversely, at low dilution rates the specific toluene degradation rates increased. Excess biomass in a trickle-bed reactor causes reduction of interfacial area and mass transfer, and increase in pressure drop. To avoid these disadvantages, the trickle-bed was moved periodically and biomass was removed with outflowing medium. The concentration of steady state biomass fixed on polyamide beads decreased hyperbolically with the dilution rate. Also, the efficiency of toluene degradation decreased from 72 to 56% with increasing dilution rate while the productivity increased. Potassium limitation generally caused a reduction in biomass, productivity, and yield while the specific degradation increased with dilution rate. This allowed the application of the principles of the chemostat to the trickle-bed reactor described here, for toluene degradation from waste gases. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 686-692, 1997.

  2. Investigation of Facies Types and Associations of Kuhlan Red Bed Formation in NW Yemen: A New Hypothesis for Origin and Depositional Environment

    Directory of Open Access Journals (Sweden)

    Mohammed A. Al-Wosabi

    2006-06-01

    Full Text Available Varieties of thirteen facies types were recognized in the Kuhlan Formation represented by red bed siliciclastic sequences of argillaceous sediments. Examination of the Kuhlan stratigraphic column included sequence relationships, lithology, sedimentary characters, structures and petrography of the dominant rock types. These facies types are grouped in three distinct associations of facies. The lower unit A comprises association of facies (Distal turbidites represented by alternates of turbidity sequences including sandstone, siltstone and thick shale beds. These facies types confirm a regressive depositional environment in deep marine shelf conditions. There are three facies types which are identified as massive sandstone, cross-bedded sandstone and pebbly sandstone facies. The middle unit B association of facies (Proximal turbedites represents glaciomarine sequences displaying high lateral and vertical facies changes of glacioturbidite sediment alternates with diamictites and tillite beds. The sequences are affected by eustatic and eustatism of the glacial advance and retreat. This unit B includes eight types of facies. These are identified as; tillite, massive diamictites, stratified diamictites, laminated siltstone/shale, deformed siltstone/mudstone, graded rhythmic siltstone, massive conglomerate and cross-stratified sandy conglomerate facies. The upper unit C association of facies is represented by shallow marine shelf sequences displaying very thick massive and locally cross-bedded sand bar sandstone overlying the laminated siltstone/shale interbeds. The upward gradual changes in mineralogical composition and color confirms the start of marine transgression and later deposited platform Amran Group. Mineralogical composition of Kuhlan sandstone displays impure dirty rocks consisting of more than 30% of argillaceous matrix, 50% of cristobalite and quartz grains, more than 10% of ferruginous cement and 10% of detrital iron oxide grains, potash

  3. Proceedings of the Workshop on in-vessel core debris retention and coolability

    International Nuclear Information System (INIS)

    1999-01-01

    This conference on in-vessel core debris retention and coolability is composed of 37 papers grouped in three sessions: session 1 (Keynote papers: Key phenomena of late phase core melt progression, accident management strategies and status quo of severe fuel damage codes, In-vessel retention as a severe accident management scheme, GAREC analyses in support of in-vessel retention concept, Latest findings of RASPLAV project); session 2 - Experiments and model development with five sub-sessions: sub-session 1 (Debris bed heat transfer: Debris and Pool Formation/Heat Transfer in FARO-LWR: Experiments and Analyses, Evaporation and Flow of Coolant at the Bottom of a Particle-Bed modelling Relocated Debris, Investigations on the Coolability of Debris in the Lower Head with WABE-2D and MESOCO-2D, Uncertainty and Sensitivity Analysis of the Heat Transfer Mechanisms in the Lower Head, Simulation of the Arrival and Evolution of Debris in a PWR Lower Head with the SFD ICARE2 code), sub-session 2 (Corium properties, molten pool natural convection, and crust formation: Physico-chemistry and corium properties for in-vessel retention, Experimental data on heat flux distribution from volumetrically heated pool with frozen boundaries, Thermal hydraulic phenomena in corium pools - numerical simulation with TOLBIAC and experimental validation with BALI, TOLBIAC code simulations of some molten salt RASPLAV experiments, SIMECO experiments on in-vessel melt pool formation and heat transfer with and without a metallic layer, Numerical investigation of turbulent natural convection heat transfer in an internally-heated melt pool and metallic layer, Current status and validation of CON2D and 3D code, Free convection of heat-generating fluid in a constrained during experimental simulation of heat transfer in slice geometry), sub-session 3 (Gap formation and gap cooling: Quench of molten aluminum oxide associated with in-vessel debris retention by RPV internal water, Experimental investigations

  4. Using simulated maps to interpret the geochemistry, formation and quality of the Blue Gem Coal Bed, Kentucky, USA

    Science.gov (United States)

    Geboy, Nicholas J.; Olea, Ricardo A.; Engle, Mark A.; Martin-Fernandez, Jose Antonio

    2013-01-01

    This study presents geostatistical simulations of coal-quality parameters, major oxides and trace metals for an area covering roughly 812 km2 of the Blue Gem coal bed in southeastern Kentucky, USA. The Blue Gem, characterized by low ash yield and low sulfur content, is an important economic resource. Past studies have characterized the Blue Gem's geochemistry, palynology and petrography and inferred a depositional setting of a planar peat deposit that transitioned to slightly domed later in its development. These studies have focused primarily on vertical geochemical trends within the coal bed. Simulated maps of chemical elements derived from 45 measured sample locations across the study area provide an opportunity to observe changes in the horizontal direction within the coal bed. As the Blue Gem coal bed shows significant vertical chemical trends, care was taken in this study to try to select samples from a single, middle portion of the coal. By revealing spatial distribution patterns of elements across the middle of the bed, associations between different components of the coal can be seen. The maps therefore help to provide a picture of the coal-forming peat bog at an instant in geologic time and allow interpretation of a depositional setting in the horizontal direction. Results from this middle portion of the coal suggest an association of SiO2 with both K2O and TiO2 in different parts of the study area. Further, a pocket in the southeast of the study area shows elevated concentrations of elements attributable to observed carbonate-phase minerals (MgO, CaO, Ba and Sr) as well as elements commonly associated with sulfide-phase minerals (Cu, Mo and Ni). Areas of relatively high ash yield are observed in the north and south of the mapped area, in contrast to the low ash yields seen towards the east. Additionally, we present joint probability maps where multiple coal-quality parameters are plotted simultaneously on one figure. This application allows researchers

  5. Timing of Late Cretaceous Gulf Coast volcanism and chronostratigraphic constraints on deposition of the Ripley Formation from a newly recognized bentonite bed, Pontotoc County, Mississippi

    Science.gov (United States)

    Vitale, E. J.; Gifford, J.; Platt, B. F.

    2017-12-01

    The Upper Cretaceous Ripley Formation is present throughout the Mississippi (MS) Embayment and contains local bentonite lenses related to regional volcanism. The Pontotoc bentonite is such a lens located near the town of Pontotoc, MS, that was strip-mined and has not been accessible since reclamation of the land. Recent investigations in Pontotoc County south of the Pontotoc bentonite site resulted in the discovery of a previously unknown bentonite bed. Litho- and biostratigraphy indicate that the bentonite is younger than known volcanism from MS. The purposes of the present investigation are 1) to test whether the new bentonite bed is correlative to the Pontotoc bentonite & 2) to recover volcanogenic zircons for U-Pb dating to better constrain timing of volcanism and chronostratigraphy of the Ripley Fm. Outcrops in an active sand pit in the field area expose 2.5 m of fine sand, and an upper gradational contact with an overlying 2.5 m of sandy clay, containing the bentonite bed. Two trenches were excavated through the outcrop, and in each trench a stratigraphic section was measured and bulk samples collected for zircons. Sampling began in the lower bounding sand and continued upsection in 1 m intervals, corresponding to the gradational contact with the bentonite, and 2 locations within the bentonite. The Ripley Fm. consists of 73 m of fossiliferous clay, sand, and calcareous sand beds. Recent stratigraphic revisions of the lateral facies in MS recognize a lower transitional clay facies, a limestone, marl, and calcareous sand facies, a sandy upper Ripley facies, and the formally named Chiwapa Sandstone Member. Ammonite biostratigraphy places the contact between the Chiwapa and the overlying Owl Creek/Prairie Bluff at 68.5 Ma. Unlike the mined area north of Pontotoc where the bentonite is within the Chiwapa, the bed here is directly above the Chiwapa section and its upper contact represents the Ripley Fm. / Owl Creek Fm. contact. Where the bentonite is present, it

  6. Debris thickness patterns on debris-covered glaciers

    Science.gov (United States)

    Anderson, Leif S.; Anderson, Robert S.

    2018-06-01

    Many debris-covered glaciers have broadly similar debris thickness patterns: surface debris thickens and tends to transition from convex- to concave-up-down glacier. We explain this pattern using theory (analytical and numerical models) paired with empirical observations. Down glacier debris thickening results from the conveyor-belt-like nature of the glacier surface in the ablation zone (debris can typically only be added but not removed) and from the inevitable decline in ice surface velocity toward the terminus. Down-glacier thickening of debris leads to the reduction of sub-debris melt and debris emergence toward the terminus. Convex-up debris thickness patterns occur near the up-glacier end of debris covers where debris emergence dominates (ablation controlled). Concave-up debris thickness patterns occur toward glacier termini where declining surface velocities dominate (velocity controlled). A convex-concave debris thickness profile inevitably results from the transition between ablation-control and velocity-control down-glacier. Debris thickness patterns deviating from this longitudinal shape are most likely caused by changes in hillslope debris supply through time. By establishing this expected debris thickness pattern, the effects of climate change on debris cover can be better identified.

  7. The fast debris evolution model

    Science.gov (United States)

    Lewis, H. G.; Swinerd, G. G.; Newland, R. J.; Saunders, A.

    2009-09-01

    The 'particles-in-a-box' (PIB) model introduced by Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] removed the need for computer-intensive Monte Carlo simulation to predict the gross characteristics of an evolving debris environment. The PIB model was described using a differential equation that allows the stability of the low Earth orbit (LEO) environment to be tested by a straightforward analysis of the equation's coefficients. As part of an ongoing research effort to investigate more efficient approaches to evolutionary modelling and to develop a suite of educational tools, a new PIB model has been developed. The model, entitled Fast Debris Evolution (FADE), employs a first-order differential equation to describe the rate at which new objects ⩾10 cm are added and removed from the environment. Whilst Talent [Talent, D.L. Analytic model for orbital debris environmental management. J. Spacecraft Rocket, 29 (4), 508-513, 1992.] based the collision theory for the PIB approach on collisions between gas particles and adopted specific values for the parameters of the model from a number of references, the form and coefficients of the FADE model equations can be inferred from the outputs of future projections produced by high-fidelity models, such as the DAMAGE model. The FADE model has been implemented as a client-side, web-based service using JavaScript embedded within a HTML document. Due to the simple nature of the algorithm, FADE can deliver the results of future projections immediately in a graphical format, with complete user-control over key simulation parameters. Historical and future projections for the ⩾10 cm LEO debris environment under a variety of different scenarios are possible, including business as usual, no future launches, post-mission disposal and remediation. A selection of results is presented with comparisons with predictions made using the DAMAGE environment model

  8. Differentiation of volcanic ash-fall and water-borne detrital layers in the Eocene Senakin coal bed, Tanjung Formation, Indonesia

    Science.gov (United States)

    Ruppert, L.F.; Moore, T.A.

    1993-01-01

    The Sangsang deposit of the Eocene Senakin coal bed, Tanjung Formation, southeastern Kalimantan, Indonesia, contains 11 layers, which are thin ( 70%). These layers are characterized by their pelitic macroscopic texture. Examination of eight of the layers by scanning-electron microscopy, energy-dispersive X-ray, and X-ray diffraction analyses show that they are composed primarily of fairly well-crystallized kaolinite, much of which is vermicular. Accessory minerals include abundant Ti oxide, rare-earth element-rich Ca and A1 phosphates, quartz that luminescences in the blue color range, and euhedral to subhedral pyroxene, hornblende, zircon, and sanidine. Although this mineral suite is suggestive of volcanic ash-fall material, only the four pelitic layers in the middle of the bed are thought to be solely derived from volcanic ash-falls on the basis of diagnostic minerals, replaced glass shards, and lithostratigraphic relationships observed in core and outcrop. The three uppermost pelitic layers contain octahedral chromites, some quartz grains that luminesce in teh orange color range, and some quartz grains that contain two-phase fluid inclusions. These layers are interpreted to be derived from a combination of volcanic ash-fall material and hydrologic transport of volcaniclastic sediment. In contrast, the lowermost pelitic layer, which contains large, rounded FeMg-rich chromites, is thought to have been dominantly deposited by water. The source of the volcanic ash-fall material may have been middle Tertiary volcanism related to plate tectonic activity between Kalimantan and Sulawesi. The volcanic ash was deposited in sufficient amounts to be preserved as layers within the coal only in the northern portions of the Senakin region: the southern coal beds in the region do not contain pelitic layers. ?? 1993.

  9. Differentiation of volcanic ash-fall and water-borne detrital layers in the Eocene Senakin coal bed, Tanjung Formation, Indonesia

    Energy Technology Data Exchange (ETDEWEB)

    Ruppert, L F; Moore, T A [US Geological Survey, Reston, VA (USA). National Center

    1993-02-01

    The Sangsang deposit of the Eocene Senakin coal bed, Tanjung Formation, southeastern Kalimantan, Indonesia, contains 11 layers, which are thin ([lt] 5 cm) and high in ash ([gt] 70%). These layers are characterized by their pelitic macroscopic texture. Examination of eight of the layers by scanning-electron microscopy, energy-dispersive X-ray, and X-ray diffraction analyses show that they are composed primarily of fairly well-crystallized kaolinite, much of which is vermicular. Accessory minerals include abundant Ti oxide, rare-earth element-rich Ca and Al phosphates, quartz that luminesces in the blue colour range, and euhedral to subhedral pyrooxene, hornblende, zircon, and sanidine. Although this mineral suite is suggestive of volcanic ash-fall material, only the four pelitic layers in the middle of the bed are thought to be solely derived from volcanic ash-falls on the basis of diagnostic minerals, replaced glass shards, and lithostratigraphic relationships observed in core and outcrop. The three uppermost pelitic layers contain octahedral chromites, some quartz grains that luminesce in the organic colour range, and some quartz grains that contain two-phase fluid inclusions. These layers are interpreted to be derived from a combination of volcanic ash-fall material and hydrologic transport of volcaniclastic sediment. In contrast, the lowermost pelitic layer, which contains large, rounded FeMg-rich chromites, is thought to have been dominantly deposited by water. The source of the volcanic ash-fall material may have been middle Tertiary volcanism related to plate tectonic activity between Kalimantan and Sulawesi. The volcanic ash was deposited in sufficient amounts to be preserved as layers within the coal only in the northern portions of the Senakin region: the southern coal beds in the region do not contain pelitic layers. 29 refs., 8 figs., 3 tabs.

  10. Experiments and simulation of a net closing mechanism for tether-net capture of space debris

    Science.gov (United States)

    Sharf, Inna; Thomsen, Benjamin; Botta, Eleonora M.; Misra, Arun K.

    2017-10-01

    This research addresses the design and testing of a debris containment system for use in a tether-net approach to space debris removal. The tether-net active debris removal involves the ejection of a net from a spacecraft by applying impulses to masses on the net, subsequent expansion of the net, the envelopment and capture of the debris target, and the de-orbiting of the debris via a tether to the chaser spacecraft. To ensure a debris removal mission's success, it is important that the debris be successfully captured and then, secured within the net. To this end, we present a concept for a net closing mechanism, which we believe will permit consistently successful debris capture via a simple and unobtrusive design. This net closing system functions by extending the main tether connecting the chaser spacecraft and the net vertex to the perimeter and around the perimeter of the net, allowing the tether to actuate closure of the net in a manner similar to a cinch cord. A particular embodiment of the design in a laboratory test-bed is described: the test-bed itself is comprised of a scaled-down tether-net, a supporting frame and a mock-up debris. Experiments conducted with the facility demonstrate the practicality of the net closing system. A model of the net closure concept has been integrated into the previously developed dynamics simulator of the chaser/tether-net/debris system. Simulations under tether tensioning conditions demonstrate the effectiveness of the closure concept for debris containment, in the gravity-free environment of space, for a realistic debris target. The on-ground experimental test-bed is also used to showcase its utility for validating the dynamics simulation of the net deployment, and a full-scale automated setup would make possible a range of validation studies of other aspects of a tether-net debris capture mission.

  11. Behavior of explosion debris clouds

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    In the normal course of events the behavior of debris clouds created by explosions will be of little concern to the atomic energy industry. However, two situations, one of them actual and one postulated, exist where the rise and spread of explosion clouds can affect site operations. The actual occurrence would be the detonation of nuclear weapons and the resultant release and transport of radioactive debris across the various atomic energy installations. Although the activity of the diffusing cloud is not of biological concern, it may still be sufficiently above background to play havoc with the normal readings of sensitive monitoring instruments. If it were not known that these anomalous readings resulted from explosion debris, considerable time and expense might be required for on-site testing and tracing. Fortunately it is usually possible, with the use of meteorological data and forecasts, to predict when individual sites are affected by nuclear weapon debris effects. The formation rise, and diffusion of weapon clouds will be discussed. The explosion of an atomic reactor is the postulated situation. It is common practice in reactor hazard analysis to assume a combination of circumstances which might result in a nuclear incident with a release of material to the atmosphere. It is not within the scope of this report to examine the manifold plausibilities that might lead to an explosion or the possible methods of release of gaseous and/or particulates from such an occurrence. However, if the information of a cloud is assumed and some idea of its energy content is obtainable, estimates of the cloud behavior in the atmosphere can be made

  12. Modelling debris flows down general channels

    Directory of Open Access Journals (Sweden)

    S. P. Pudasaini

    2005-01-01

    Full Text Available This paper is an extension of the single-phase cohesionless dry granular avalanche model over curved and twisted channels proposed by Pudasaini and Hutter (2003. It is a generalisation of the Savage and Hutter (1989, 1991 equations based on simple channel topography to a two-phase fluid-solid mixture of debris material. Important terms emerging from the correct treatment of the kinematic and dynamic boundary condition, and the variable basal topography are systematically taken into account. For vanishing fluid contribution and torsion-free channel topography our new model equations exactly degenerate to the previous Savage-Hutter model equations while such a degeneration was not possible by the Iverson and Denlinger (2001 model, which, in fact, also aimed to extend the Savage and Hutter model. The model equations of this paper have been rigorously derived; they include the effects of the curvature and torsion of the topography, generally for arbitrarily curved and twisted channels of variable channel width. The equations are put into a standard conservative form of partial differential equations. From these one can easily infer the importance and influence of the pore-fluid-pressure distribution in debris flow dynamics. The solid-phase is modelled by applying a Coulomb dry friction law whereas the fluid phase is assumed to be an incompressible Newtonian fluid. Input parameters of the equations are the internal and bed friction angles of the solid particles, the viscosity and volume fraction of the fluid, the total mixture density and the pore pressure distribution of the fluid at the bed. Given the bed topography and initial geometry and the initial velocity profile of the debris mixture, the model equations are able to describe the dynamics of the depth profile and bed parallel depth-averaged velocity distribution from the initial position to the final deposit. A shock capturing, total variation diminishing numerical scheme is implemented to

  13. The effect of debris-flow composition on runout distance

    Science.gov (United States)

    de Haas, Tjalling; Braat, Lisanne; Leuven, Jasper; Lokhorst, Ivar; Kleinhans, Maarten

    2015-04-01

    Estimating runout distance is of major importance for the assessment and mitigation of debris-flow hazards. Debris-flow runout distance depends on debris-flow composition and topography, but state-of-the-art runout prediction methods are mainly based on topographical parameters and debris-flow volume, while composition is generally neglected or incorporated in empirical constants. Here we experimentally investigated the effect of debris-flow composition and topography on runout distance. We created the first small-scale experimental debris flows with self-formed levees, distinct lobes and morphology and texture accurately resembling natural debris flows. In general, the effect of debris-flow composition on runout distance was larger than the effect of topography. Enhancing channel slope and width, outflow plain slope, debris-flow size and water fraction leads to an increase in runout distance. However, runout distance shows an optimum relation with coarse-material and clay fraction. An increase in coarse-material fraction leads to larger runout distances by increased grain collisional forces and more effective levee formation, but too much coarse debris causes a large accumulation of coarse debris at the flow front, enhancing friction and decreasing runout. An increase in clay fraction initially enlarges the volume and viscosity of the interstitial fluid, liquefying the flow and enhancing runout, while a further increase leads to very viscous flows with high yield strength, reducing runout. These results highlight the importance and further need of research on the relation between debris-flow composition and runout distance. Our experiments further provide valuable insight on the effects of debris-flow composition on depositional mechanisms and deposit morphology.

  14. National waste terminal storage repository in a bedded salt formation for spent unreprocessed fuel. Volume I. Conceptual design report

    International Nuclear Information System (INIS)

    1978-12-01

    In February 1976, the Energy Research and Development Administration (ERDA), now the Department of Energy (DOE), established a National Waste Terminal Storage (NWTS) program. As a part of this program, two parallel conceptual design efforts were initiated in January 1977. One was for deep geologic storage, in domed salt, of high level waste resulting from the reprocessing of spent fuel. The other was for deep geologic storage of unreprocessed spent fuel in bedded salt. These two concepts are identified as NWTS Repository 1 and Repository 2, respectively. Repository 2 (NWTSR2) is the concept which is covered by this Conceptual Design Report. Volume I of the conceptual design report contains the following information: physical description of the report; project purpose and justification; principal safety, fire, and health hazards; environmental impact considerations; quality assurance considerations; assessment of operational interfaces; assessment of research and development interfaces; project schedule; proposed method of accomplishment; summary cost estimate; and outline specifications. The conceptual design for Repository 2 was developed in sufficient detail to permit determination of scope, engineering feasibility, schedule, and cost estimates, all of which are necessary for planning and budgeting the project

  15. National waste terminal storage repository in a bedded salt formation for spent unreprocessed fuel. Quality assurance program for licensing

    International Nuclear Information System (INIS)

    1978-12-01

    A National Waste Terminal Storage Repository, in bedded salt, for spent unreprocessed fuel is the subject of a conceptual design project which began in January 1977. This volume presents a preliminary quality assurance program to guide the license applicant in developing a detailed program that will be compatible with anticipated National Waste Terminal Storage (NWTSR2) contracting arrangements and provide the documentation required by regulatory bodies. This QA program is designed to provide confidence that the quality-related activities pertaining to safety-related structures, systems, and components will be identified and controlled. Specific responsibilities for quality-related activities are documented and assigned to personnel and organizations for the major phases of facility design and construction. These responsibilities encompass a broad range of activities and are addressed in this preliminary program. The quality assurance program elements are organized and discussed herein as follows: (1) quality assurance during design and construction; (2) the applicant (DOE); (3) siting contractor; (4) architect/engineer; (5) project field management; and (6) operations contractor

  16. LEGACY - EOP Marine Debris

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data contains towed diver surveys of and weights of marine debris removed from the near shore environments of the NWHI.

  17. Formation of chlorinated organic compounds in fluidized bed combustion of recycled fuels; Kloorattujen orgaanisten yhdisteiden muodostuminen kierraetyspolttoaineiden leijukerrospoltossa

    Energy Technology Data Exchange (ETDEWEB)

    Vesterinen, R.; Kallio, M.; Kirjalainen, T.; Kolsi, A.; Merta, M. [VTT Energy, Jyvaeskylae (Finland)

    1997-10-01

    Four tests of co-combustion of recycled fuels (REP) with peat and coal in the 15 kW fluidized bed reactor were performed. The recycled fuel was so-called dry fraction in four vessels sampling at Keltinmaeki. In three tests a part of peat energy was replaced with coal. The mixtures were prepared so that in all mixtures 25 % of energy was recycled fuel and 75 % was either peat or the mixture of peat and coal. The concentrations of polyaromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and chlorophenols decreased with increasing part of coal due to the increasing sulphur/chlorine ratio. Principal Component Analysis (PCA) and Partial Least Square regression analysis (PLS) showed that the chlorine, copper and sulphur contents of the fuel effected most on the concentrations of chlorophenols, chlorobenzenes, PCBs and PCDDs/PCDFs. Other variables influencing on a model were the lead concentration and the sulphur/chlorine ratio in fuel and the hydrogen chloride concentration of the flue gas. The concentrations of chlorophenols and chlorobenzenes were also significant for PCDD/PCDF concentrations in flue gas. The sulphur, chlorine, copper and chromium contents in fly ash and the temperature of the reactor influenced on the chlorophenol, chlorobenzene, PCB and PCDD/PCDF concentrations in fly ash. The chlorophenol and chlorobenzene contents in fly ash, the sulphur/chlorine ratio and the lead content in fuel, the sulphur dioxide, hydrogen chloride and carbon monoxide concentrations in flue gas had also influence on PCDD/PCDF concentrations in fly ash

  18. Space Debris & its Mitigation

    Science.gov (United States)

    Kaushal, Sourabh; Arora, Nishant

    2012-07-01

    Space debris has become a growing concern in recent years, since collisions at orbital velocities can be highly damaging to functioning satellites and can also produce even more space debris in the process. Some spacecraft, like the International Space Station, are now armored to deal with this hazard but armor and mitigation measures can be prohibitively costly when trying to protect satellites or human spaceflight vehicles like the shuttle. This paper describes the current orbital debris environment, outline its main sources, and identify mitigation measures to reduce orbital debris growth by controlling these sources. We studied the literature on the topic Space Debris. We have proposed some methods to solve this problem of space debris. We have also highlighted the shortcomings of already proposed methods by space experts and we have proposed some modification in those methods. Some of them can be very effective in the process of mitigation of space debris, but some of them need some modification. Recently proposed methods by space experts are maneuver, shielding of space elevator with the foil, vaporizing or redirecting of space debris back to earth with the help of laser, use of aerogel as a protective layer, construction of large junkyards around international space station, use of electrodynamics tether & the latest method proposed is the use of nano satellites in the clearing of the space debris. Limitations of the already proposed methods are as follows: - Maneuvering can't be the final solution to our problem as it is the act of self-defence. - Shielding can't be done on the parts like solar panels and optical devices. - Vaporizing or redirecting of space debris can affect the human life on earth if it is not done in proper manner. - Aerogel has a threshold limit up to which it can bear (resist) the impact of collision. - Large junkyards can be effective only for large sized debris. In this paper we propose: A. The Use of Nano Tubes by creating a mesh

  19. National waste terminal storage repository in a bedded salt formation for spent unreprocessed fuel. Special study No. 1. Twenty-five-year retrievability, decommissioning cost estimate

    International Nuclear Information System (INIS)

    1978-11-01

    This estimate covers decommissioning costs of facilities for the receipt, handling, and storage in bedded salt of canistered spent fuel assemblies from both BWR and PWR commercial power plants. The estimate includes all decommissioning costs for a repository, based on 25-year retrievability, constructed in accordance with the design shown in Conceptual Design Report (CDR), as modified by Special Study No. 1 (KE Report No. 78-60-RE) and decommissioned in accordance with the program outlined in the Conceptual Design Description Report, KE Report No. 78-58-R. Costs for Operating Contractor personnel on the site at this time are included in this report and not in the Operating Cost Estimate (KE Report 78-63-RE). The operating cost estimates end with the completion of storage room backfilling. The three major elements of decommissioning are: demolition of surface facilities, backfilling of main entries and airways, and shaft liner removal and shaft plugging. EDIT, ECON, and DELOX computer programs and a chart of accounts were furnished by UCC-ND under direction of the Government and the line item-capital-cost estimate was prepared according to the prescribed format. The decommissioning cost estimate referenced herein is in the same format as its companion line item-capital-cost estimate KE Report 78-62-RE

  20. Formation of the Ni3Nb δ-Phase in Stress-Relieved Inconel 625 Produced via Laser Powder-Bed Fusion Additive Manufacturing

    Science.gov (United States)

    Lass, Eric A.; Stoudt, Mark R.; Williams, Maureen E.; Katz, Michael B.; Levine, Lyle E.; Phan, Thien Q.; Gnaeupel-Herold, Thomas H.; Ng, Daniel S.

    2017-11-01

    The microstructural evolution of laser powder-bed additively manufactured Inconel 625 during a post-build stress-relief anneal of 1 hour at 1143 K (870 °C) is investigated. It is found that this industry-recommended heat treatment promotes the formation of a significant fraction of the orthorhombic D0a Ni3Nb δ-phase. This phase is known to have a deleterious influence on fracture toughness, ductility, and other mechanical properties in conventional, wrought Inconel 625; and is generally considered detrimental to materials' performance in service. The δ-phase platelets are found to precipitate within the inter-dendritic regions of the as-built solidification microstructure. These regions are enriched in solute elements, particularly Nb and Mo, due to the micro-segregation that occurs during solidification. The precipitation of δ-phase at 1073 K (800 °C) is found to require up to 4 hours. This indicates a potential alternative stress-relief processing window that mitigates δ-phase formation in this alloy. Ultimately, a homogenization heat treatment is recommended for additively manufactured Inconel 625 because the increased susceptibility to δ-phase precipitation increases the possibility for significant degradation of materials' properties in service.

  1. Continental Environment of Triassic Alluvial Beds in the Northern North Sea Area: Core Examples from the Lunde Formation, Snorre Field

    Energy Technology Data Exchange (ETDEWEB)

    Nystuen, Johan Petter; Bergan, Morten

    1999-07-01

    Alluvial processes transport and deposit gravel, sand and mud in a series of depositional systems such as alluvial fans, fluvial channels, floodplain and lacustrine basins. In the northernmost part of the North Sea alluvial sandstones form major reservoir rocks in several oil fields in the Tampen Spur area. In the Snorre Field, the Norian- Early Rhaetian Lunde Formation has given a great database from exploration and production wells, seismic studies, reservoir modelling, production experience and comparative analogue studies on facies distribution, alluvial architecture, heterogeneities and reservoir properties of alluvial successions. The Lunde Formation is subdivided in three members, the lower, middle and upper Lunde members, with the upper member being the main part of the Lunde reservoir rocks. The scope of presenting core samples from the upper Lunde member is to demonstrate main alluvial facies and facies associations, how facies analysis proceeds into construction of conceptual fluvial models that in turn are fundamental in evaluation of reservoir heterogeneities and reservoir modelling. The upper Lunde member consists of repeated units of red and grey sandstone and mudstone. Sandstones are dominantly medium-grained with common range from coarse- to very fine-grained. A basic building stone of the alluvial succession consists of a thick single- or multi-storey sandstone body overlain by a thick mudstone unit. Such couplets form allostratigraphic units and define the main reservoir zones.

  2. Tonian paleomagnetism of the red beds of Madiyi Formation, lower Banxi Group in South China: implications for pre-Sturtian climate, Rodinia reconstruction and true polar wander

    Science.gov (United States)

    Hanbiao, X.; Zhang, S.; Xiao, Q.; Li, H.; Chang, L.; Fu, H.; Liu, R.

    2017-12-01

    We present a new Tonian paleomagnetic pole from the red beds of ca. 810 Ma Madiyi Formation, lower Banxi Group in the central South China Block (SCB). Detailed thermal demagnetization reveals two distinct magnetic components among the samples. A low temperature component (LTC), removed from almost all the samples below 580°C, yielded a paleopole at 68.0°N, 211.7°E (A95=1.9) that is close to the pole of late Jurassic. The high temperature component (HTC), isolated between 580-690°C, gave a mean direction of D=310.0°, I=57.4°, α95=3.7 (108 samples of 13 sites) after bedding correction, corresponding to a paleomagnetic pole at 47.6°N, 46.7°E (A95=5.6°). The HTC passed a reversal test on 95% and 99% confidence level. Directional distribution of the HTC show significant elongation which may indicate inclination shallowing, and the inclination was corrected to 75.1° using E/I technique, corresponding to a paleolatitude at 60.8±3.4° of research area. The paleopole calculated from the E/I-corrected HTC is at 44.8°N, 80.2°E (A95=3.4°), being significantly distinct from any younger poles of the SCB. This new pole plus existing high quality paleomagnetic poles from the SCB demonstrate that the SCB experienced a polar-equatorial region drifting tendency from 825 Ma to Cambrian. The high-paleolatitude red beds rather than glacial sediments deposited in the SCB, combined with coeval widespread evaporative in other continents, possibly suggest pre-Cryogenian global greenhouse climate. In our reconstruction at 800 Ma, the SCB was placed on the northwest periphery of Rodinia, with its western margin adjacent to the northern India, rather than occupying a central position of Rodinia. The distribution of 825-750 Ma poles of the SCB, East Svalbard, Australia, Laurentia, India along a great arc may be associated with true polar wander around 800 Ma.

  3. SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head

    International Nuclear Information System (INIS)

    Siefken, L. J.; Harvego, E. A.

    2000-01-01

    A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model has been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material may permeate to near the bottom of a 1m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material was calculated to cause a 12% increase in the heat flux on the external surface of the lower head

  4. The use of dielectric heating in particulate bed dryout experiments

    International Nuclear Information System (INIS)

    Stevens, G.F.; Willshire, S.J.

    1984-09-01

    Decay-heated, liquid-saturated debris beds arise in hypothetical severe accidents with LMFBR and PWR, and a large international effort is currently engaged in experimental studies of the cooling limitations of such beds. Dryout is one of the important cooling limitations. Dielectric heating offers a means of closely simulating decay heating in beds of irregular particles, and is under development at AEE Winfrith for application to experimental studies of dryout. This report describes progress to date. (author)

  5. Refined model for the coolability of core debris with flow entry from the bottom

    International Nuclear Information System (INIS)

    Schulenberg, T.; Mueller, U.

    1986-01-01

    Within the context of a hypothetical severe accident in light water reactors also heat generating debris beds of a coarse particle size are discussed. A refined model for two-phase flow in particle beds is presented. Compared to previous models this model takes into account the effect of interfacial drag forces between liquid and vapor. These effects are important in coarse debris beds. The model is based on the momentum equations for separated flow, which are closed by empirical relations for the wall shear stress and the interfacial drag. When the refined model is applied to LWR severe accident scenarios an increased dryout heat flux is predicted for debris beds with flow entry from the bottom driven by a moderate downcomer head

  6. Disaster Debris Recovery Database - Landfills

    Data.gov (United States)

    U.S. Environmental Protection Agency — The US EPA Disaster Debris Recovery Database (DDRD) promotes the proper recovery, recycling, and disposal of disaster debris for emergency responders at the federal,...

  7. Disaster Debris Recovery Database - Recovery

    Data.gov (United States)

    U.S. Environmental Protection Agency — The US EPA Disaster Debris Recovery Database (DDRD) promotes the proper recovery, recycling, and disposal of disaster debris for emergency responders at the federal,...

  8. Formation of N2 in the fixed-bed pyrolysis of low rank coals and the mechanisms; Koteisho netsubunkai ni okeru teitankatan kara no N2 no sisei

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z.; Otsuka, Y. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    In order to establish coal NOx preventive measures, discussions were given on formation of N2 in the fixed-bed pyrolysis of low rank coals and the mechanisms thereof. Chinese ZN coal and German RB coal were used for the discussions. Both coals do not produce N2 at 600{degree}C, and the main product is volatile nitrogen. Conversion into N2 does not depend on heating rates, but increases linearly with increasing temperature, and reaches 65% to 70% at 1200{degree}C. In contrast, char nitrogen decreases linearly with the temperature. More specifically, these phenomena suggest that the char nitrogen or its precursor is the major supply source of N2. When mineral substances are removed by using hydrochloric acid, their catalytic action is lost, and conversion into N2 decreases remarkably. Iron existing in ion-exchanged condition in low-rank coal is reduced and finely diffused into metallic iron particles. The particles react with heterocyclic nitrogen compounds and turn into iron nitride. A solid phase reaction mechanism may be conceived, in which N2 is produced due to decomposition of the iron nitride. 5 refs., 4 figs., 1 tab.

  9. Space Debris Mitigation Guidelines

    Science.gov (United States)

    Johnson, Nicholas L.

    2011-01-01

    The purpose of national and international space debris mitigation guides is to promote the preservation of near-Earth space for applications and exploration missions far into the future. To accomplish this objective, the accumulation of objects, particularly in long-lived orbits, must be eliminated or curtailed.

  10. The characteristics of bed agglomeration during fluidized bed combustion of eucalyptus bark

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Tia, Suvit

    2015-01-01

    The bed agglomeration behaviors were investigated experimentally when eucalyptus bark was burning tested in a laboratory scale fluidized bed reactor. The focuses of this work were the influences of operating conditions and bed materials on the bed agglomeration tendency and the elucidation in the behaviors of fuel inorganic elements and the governing mode of the agglomeration. It was found that the defluidization caused by the bed agglomeration was clearly detectable from the decrease in measured bed pressure. The growth of bed particle and accumulation of agglomerates during combustion provided the partial to complete defluidization. The defluidization was promoted by the increase of bed temperature and bed particle size, and the decrease of fluidizing air velocity. The SEM-EDS analyses revealed that the bed agglomeration was mainly attributed to the formation of potassium silicate compounds as liquid phase during the combustion. This was initiated by the chemical reaction between the bed particle and the released ash constituents. In this study, the inorganic migration from fuel particle to bed particle was likely dominated by the condensation/reaction. The thermodynamic examination by ternary phase diagram analysis corroborated that the liquid phase formation of the ash derived materials controlled the agglomeration. The alumina sand prevented the bed agglomeration since it was inactive in the formation of viscous molten substances during combustion at the observed temperatures. - Highlights: • The behaviors of bed agglomeration were studied during the fluidized bed combustion of eucalyptus bark. • The increase in bed temperature and sand size, and the decrease of air velocity promoted bed defluidization. • The formation of molten potassium silicate compounds conduced to the bed agglomeration. • Condensation/reaction was the dominant inorganic migration mechanism from fuel particle to bed particle. • The alumina sand prevented effectively the bed

  11. SCDAP/RELAP5 Modeling of Movement of Melted Material Through Porous Debris in Lower Head

    International Nuclear Information System (INIS)

    Siefken, L. J.

    1998-01-01

    Designs are described for implementing models for calculating the movement of melted material through the interstices in a matrix of porous debris in the lower head of a reactor vessel. The COUPLE model in SCDAP/RELAP5 represents both the porous and nonporous debris that results from core material slumping into the lower head during a severe accident in a Light Water Reactor. Currently, the COUPLE model has no capability to model the movement of material that melts within a matrix of porous material. The COUPLE model also does not have the capability to model the movement of liquefied core plate material that slumps onto a porous debris bed in the lower head. In order to advance beyond the assumption the liquefied material always remains stationary, designs are developed for calculations of the movement of liquefied material through the interstices in a matrix of porous material. Correlations are identified for calculating the permeability of the porous debris and for calculating the rate of flow of liquefied material through the interstices in the debris bed. Correlations are also identified for calculating the relocation of solid debris that has a large amount of cavities due to the flowing away of melted material. Equations are defined for calculating the effect on the temperature distribution in the debris bed of heat transported by moving material and for changes in effective thermal conductivity and heat capacity due to the movement of material. The implementation of these models is expected to improve the calculation of the material distribution and temperature distribution of debris in the lower head for cases in which the debris is porous and liquefied material is present within the porous debris

  12. OECD/CSNI Workshop on In-Vessel Core Debris Retention and Coolability - Summary and Conclusions

    International Nuclear Information System (INIS)

    Behbahani, Ali-Reza; Drozd, Andrzej; Kim, Sang-Baik; Micaelli, Jean-Claude; Okkonen, Timo; Sugimoto, Jun; Trambauer, Klaus; Tuomisto, Harri

    1999-01-01

    In the spring of 1994 an OECD Workshop on Large Pool Heat transfer was held in Grenoble. The scope of this workshop was the investigation of (1) molten pool heat transfer, (2) heat transfer to the surrounding water, and (3) the feasibility of in-vessel core debris cooling through external cooling of the vessel. Since this time, experimental test series have been completed (e.g., COPO, ULPU, CORVIS) and new experimental programs (e.g., BALI, SONATA, RASPLAV, debris and gap heat transfer) have been established to consolidate and expand the data base for further model development and to improve the understanding of in-vessel debris retention and coolability in a nuclear power plant. Discussions within the CSNI's PWG-2 and the Task Group on Degraded Core Cooling (TG-DCC) have led to the conclusion that the time was ripe for organizing a new international Workshop with the objectives: - to review the results of experimental research that has been conducted in this area; - to exchange information on the results of member countries experiments and model development on in-vessel core debris retention and coolability; - to discuss areas where additional experimental research is needed in order to provide an adequate data base for analytical model development for core debris retention and coolability. The scope of this workshop was limited to the phenomena connected to in-vessel core debris retention and coolability and did not include steam explosion and fission product issues. The workshop was structured into the following sessions: Key note papers; Experiments and model development; Debris bed heat transfer; Corium properties, molten pool convection and crust formation; Gap formation and gap cooling; Creep behaviour of reactor pressure vessel lower head; Ex-vessel boiling and critical heat flux phenomena; Scaling to reactor severe accident conditions and reactor applications. Compared to the previous workshop held in Grenoble in 1994, large progress has been made in the

  13. Bed agglomeration characteristics of palm shell and corncob combustion in fluidized bed

    International Nuclear Information System (INIS)

    Chaivatamaset, Pawin; Sricharoon, Panchan; Tia, Suvit

    2011-01-01

    Bed particle agglomeration was studied experimentally in an atmospheric laboratory scale fluidized bed combustor using quartz sand as bed material. Palm shell and corncob were tested. The objectives of the study were (i) to describe the contributions of the biomass ash properties and the operating conditions on the bed agglomeration tendency in term of the bed defluidization time (t def ) and the extent of potassium accumulation in the bed (K/Bed) and (ii) to further elucidate the ash inorganic behaviors and the governing bed agglomeration mechanisms. Defluidization caused by the bed agglomeration was experienced in all experiments during combustion of these biomasses, as a consequence of the presence of potassium in biomass. The experimental results indicated that biomass ash characteristics were the significant influence on the bed agglomeration. The increasing bed temperature, bed particle size and static bed height and the decreasing fluidizing air velocity enhanced the bed agglomeration tendency. The SEM/EDS analyses on the agglomerates confirmed that the agglomeration was attributed to the formation of potassium silicate liquid enriched on the surface of quartz sand particles in conjunction with the high surface temperature of the burning biomass char particles. Thermodynamic examination based on the phase diagram analysis confirmed that the molten phase formation was responsible for the agglomeration. In this study, the high molten ash fraction resulting from the high potassium content in biomass promoted the agglomeration and thus defluidization. - Highlights: → Palm shell and corncob of Thailand are tested their bed agglomeration behaviors during fluidized bed combustion. → The increase of bed temperature, bed particle size and static bed height and the decrease of air velocity enhance bed agglomeration. → The formation of ash derived potassium silicate melts enriched on sand surface is the key process. → The collision between char and sand

  14. Experimental observations of granular debris flows

    Science.gov (United States)

    Ghilardi, P.

    2003-04-01

    Various tests are run using two different laboratory flumes with rectangular cross section and transparent walls. The grains used in a single experiment have an almost constant grain sizes; mean diameter ranges from 5 mm to 20 mm. In each test various measurements are taken: hydrograms, velocity distribution near the transparent walls and on the free surface, average flow concentration. Concentration values are measured taking samples. Velocity distributions are obtained from movies recorded by high speed video cameras capable of 350 frames per second; flow rates and depth hydrograms are computed from the same velocity distributions. A gate is installed at the beginning of one of the flumes; this gate slides normally to the bed and opens very quickly, reproducing a dam-break. Several tests are run using this device, varying channel slope, sediment concentration, initial mixture thickness before the gate. Velocity distribution in the flume is almost constant from left to right, except for the flow sections near the front. The observed discharges and velocities are less than those given by a classic dam break formula, and depend on sediment concentration. The other flume is fed by a mixture with constant discharge and concentration, and is mainly used for measuring velocity distributions when the flow is uniform, with both rigid and granular bed, and to study erosion/deposition processes near debris flow dams or other mitigation devices. The equilibrium slope of the granular bed is very close to that given by the classical equilibrium formulas for debris flow. Different deposition processes are observed depending on mixture concentration and channel geometry.

  15. Distribution of discontinuous mudstone beds within wave-dominated shallow-marine deposits: Star Point Sandstone and Blackhawk Formation, Eastern Utah, USA

    OpenAIRE

    Eide, Christian; Buckley, Simon; Howell, John

    2017-01-01

    Deposits of wave-dominated shorelines are typically considered to act as relatively simple hydrocarbon reservoirs and are commonly modeled as “tanks of sand”. However, important heterogeneities that can act as barriers to fluid flow occur at the parasequence, bedset and bed scales, especially in viscous oil or low permeability oil fields. Heterogeneities at the parasequence and bedset scale have been well-studied, but discontinuous mudstone-beds occurring within the shoreface have received li...

  16. TMI-2 core debris analytical methods and results

    International Nuclear Information System (INIS)

    Akers, D.W.; Cook, B.A.

    1984-01-01

    A series of six grab samples was taken from the debris bed of the TMI-2 core in early September 1983. Five of these samples were sent to the Idaho National Engineering Laboratory for analysis. Presented is the analysis strategy for the samples and some of the data obtained from the early stages of examination of the samples (i.e., particle size-analysis, gamma spectrometry results, and fissile/fertile material analysis)

  17. Response of a Brook Trout Population and Instream Habitat to a Catastrophic Flood and Debris Flow

    Science.gov (United States)

    Criag N. Roghair; C. Andrew Dolloff; Martin K. Underwood

    2002-01-01

    In June 1995, a massive flood and debris flow impacted fish and habitat along the lower 1.9 km of the Staunton River, a headwater stream located in Shenandoah National Park, Virginia. In the area affected by debris flow, the stream bed was scoured and new substrate materials were deposited, trees were removed from a 30-m-wide band in the riparian area, and all fish...

  18. Experimental simulation of fragmentation and stratification of core debris on the core catcher of a fast breeder reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pillai, Dipin S.; Vignesh, R. [Indian Institute of Technology, Chennai, Tamil Nadu (India); Sudha, A. Jasmin, E-mail: jasmin@igcar.gov.in [Safety Engineering Division, Reactor Design Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India); Pushpavanam, S.; Sundararajan, T. [Indian Institute of Technology, Chennai, Tamil Nadu (India); Nashine, B.K.; Selvaraj, P. [Safety Engineering Division, Reactor Design Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

    2016-05-15

    Highlights: • Fragmentation of two simultaneous metals jets in a bulk coolant analysed. • Particle size from experiments compared with theoretical analysis. • Jet breakup modes explained using dimensionless numbers. • Settling aspects of aluminium and lead debris on collector plate studied. • Results analysed in light of core debris settling on core catcher in a FBR. - Abstract: The complex and coupled phenomena of two simultaneous molten metal jets fragmenting inside a quiescent liquid pool and settling on a collector plate are experimentally analysed in the context of safety analysis of a fast breeder reactor (FBR) in the post accident heat removal phase. Following a hypothetical core melt down accident in a FBR, a major portion of molten nuclear fuel and clad/structural material which are collectively termed as ‘corium’ undergoes fragmentation in the bulk coolant sodium in the lower plenum of the reactor main vessel and settles on the core catcher plate. The coolability of this decay heat generating debris bed is dependent on the particle size distribution and its layering i.e., stratification. Experiments have been conducted with two immiscible molten metals of different densities poured inside a coolant medium to understand their fragmentation behaviour and to assess the possibility of formation of a stratified debris bed. Molten aluminium and lead have been used as simulants in place of molten stainless steel and nuclear fuel to facilitate easy handling. This paper summarizes the major findings from these experiments. The fragmentation of the two molten metals are explained in the light of relevant dimensionless numbers such as Reynolds number and Weber Number. The mass median diameter of the fragmented debris is predicted from nonlinear stability analysis of slender jets for lead jet and using Rayleigh's classical theory of jet breakup for aluminium jet. The agreement of the predicted values with the experimental results is good. These

  19. Persistent marine debris

    International Nuclear Information System (INIS)

    Levy, E.M.

    1992-01-01

    In this paper the distribution of persistent marine debris, adrift on world oceans and stranded on beaches globally, is reviewed and related to the known inputs and transport by the major surface currents. Since naturally occurring processes eventually degrade petroleum in the environment, international measures to reduce the inputs have been largely successful in alleviating oil pollution on a global, if not on a local, scale. Many plastics, however, are so resistant to natural degradation that merely controlling inputs will be insufficient, and more drastic and costly measures will be needed to cope with the emerging global problem posed by these materials

  20. The effect of bed non-uniformities and porosity of particles on dryout in boiling particle beds

    International Nuclear Information System (INIS)

    Macbeth, R.V.; Mogford, D.J.; Willshire, S.J.

    1988-03-01

    This report relates to an on-going experimental programme concerned with the coolability of beds of reactor core debris or rubble immersed in a liquid coolant, as might occur in an accident situation. The objectives are to develop experimental techniques, improve the understanding of bed cooling mechanisms, determine dry-out limitations of various bed configurations and particle shapes and sizes and devise ways of improving bed coolability. The report concentrates on a recently discovered effect on bed coolability of particle porosity, such as exists in fragmented UO 2 fuel pellets. It is shown that porosity can lower bed dry-out powers by a factor of 4 or 5. A mechanism which explains the effect is presented. The report also gives results of bed non-uniformities obtained by mixing glass particles with the dielectrically heated 'ferrite' particles used in the experiments. (author)

  1. Effects of debris generated by chemical reactions on head loss through emergency-core cooling-system strainers

    International Nuclear Information System (INIS)

    Howe, K.; Ghosh, A.; Maji, A.K.; Letellier, B.C.; Johns, R.; Chang, T.Y.

    2004-01-01

    The effect of debris generated during a loss of coolant accident (LOCA) on the emergency core cooling system (ECCS) strainers has been studied via numerous avenues over the last several years. The research described in this manuscript examines the generation and effect of secondary materials -- not debris generated in the LOCA itself, but materials created by chemical reactions between exposed surfaces/debris and cooling system water. The secondary materials studied in the research were corrosion products from exposed metallic surfaces and paint chips that may precipitate out of solution, with a focus on the corrosion products of aluminium, iron, and zinc. The processes of corrosion and leaching of metals with subsequent precipitation is important because: (1) the surface area of exposed metal inside containment represents a large potential source term, even for slow chemical reactions; the chemical composition of the cooling system water (boric acid, lithium, etc.) may affect corrosion or precipitation in ways that have not been studied thoroughly in the past; and (3) an eyewitness report of the presence of gelatinous material in the Three Mile Island containment pool after the 1979 accident suggests the formation of a secondary material that has not been examined under the generic safety issue (GSI)-191 research program. This research was limited in scope and consisted only of small-scale tests. Several key questions were investigated: (1) do credible corrosion mechanisms exist for leaching metal ions from bulk solid surfaces or from zinc-based paint chips, and if so, what are the typical rate constants? (2) can corrosion products accumulate in the containment pool water to the extent that they might precipitate as new chemical species at pH and temperatures levels that are relevant to the LOCA accident sequence? and (3) how do chemical precipitants affect the head loss across an existing fibrous debris bed? A full report of the research is available. (authors)

  2. In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

    Science.gov (United States)

    Kean, J.W.; Staley, D.M.; Cannon, S.H.

    2011-01-01

    Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows. copyright. 2011 by the American Geophysical Union.

  3. Extensions to SCDAP/RELAP5/MOD2 debris analysis models for the severe accident analysis of Savannah River Site (SRS) reactors preliminary design report

    International Nuclear Information System (INIS)

    Siefken, L.J.; Moore, R.L.

    1989-06-01

    Proposed extensions to the debris analysis model in the SCDAP/RELAP5 code to perform severe accident analyses of Savannah River Plant reactors are described. Designs are presented for the following areas of development: (a) calculating convective and radiative heat transfer at the surfaces of a debris region; (b) calculating heatup of a structure and supported debris that interfaces with several fluid control volumes; (c) modeling the addition of transported material to the surfaces of any structure represented by the debris analysis model; (d) calculating the two-dimensional heatup of an arbitrary number of structures in the reactor system; (e) modeling the effect of natural convection of liquefied material on heat transfer in a debris bed; and (f) modeling fission product release and aerosol generation in a debris bed. 11 refs., 12 figs., 7 tabs

  4. Wholesale debris removal from LEO

    Science.gov (United States)

    Levin, Eugene; Pearson, Jerome; Carroll, Joseph

    2012-04-01

    Recent advances in electrodynamic propulsion make it possible to seriously consider wholesale removal of large debris from LEO for the first time since the beginning of the space era. Cumulative ranking of large groups of the LEO debris population and general limitations of passive drag devices and rocket-based removal systems are analyzed. A candidate electrodynamic debris removal system is discussed that can affordably remove all debris objects over 2 kg from LEO in 7 years. That means removing more than 99% of the collision-generated debris potential in LEO. Removal is performed by a dozen 100-kg propellantless vehicles that react against the Earth's magnetic field. The debris objects are dragged down and released into short-lived orbits below ISS. As an alternative to deorbit, some of them can be collected for storage and possible in-orbit recycling. The estimated cost per kilogram of debris removed is a small fraction of typical launch costs per kilogram. These rates are low enough to open commercial opportunities and create a governing framework for wholesale removal of large debris objects from LEO.

  5. Formation and destruction mechanisms of nitrogen oxides during coal combustion in circulating fluidized beds; Mecanismes de formation et de destruction des oxydes d`azote lors de la combustion du charbon en lit fluidise circulant

    Energy Technology Data Exchange (ETDEWEB)

    Borrel, G.; Lecuyer, I. [Universite du Haut-Rhin, 68 - Mulhouse (France)

    1997-01-01

    Formation and reduction of nitrogen oxides (NO and N{sub 2}O) during coal combustion in a circulating fluidized bed (CFBC) are very complicated and yet badly known. The aim of the present study was to better characterize these phenomena on a small-sized experimental unit (reactor diameter: 5 cm), with the possibility to re-inject the solids in the bottom of the furnace, as in a real industrial unit. This should allow then to develop a numerical set of chemical reactions involving the nitrogen oxides. The experimental results showed that coal ash plays a great role in reducing nitrogen oxides, the determining parameter being the quantity of unburnt carbon remaining in the ash. The study then detailed the interaction between nitrogen oxides and de-volatilized (char) according to the temperature, NO{sub x} concentration and the mass of solid. In the absence of oxygen small quantities of char can very significantly reduce NO as well as N{sub 2}O. It was possible to establish destruction kinetics on these particles, and orders of reaction could be determined versus the NO{sub x} concentration and the char particle mass (heterogeneous phase chemical reactions). Then, the coal pyrolysis study enabled to identify the products released during coal devolatilization and thermogravimetric analyses displayed several successive weight losses due CO, CO{sub 2} and CH{sub 4} releases, during a linear temperature increase. Lastly coal combustion was studied in the small pilot with variable experimental conditions. Using the previous experimental was studied in the small pilot with variable experimental conditions. Using the previous experimental results, a model was developed to calculate NO{sub x} concentrations during the coal combustion and validated. The NO and N{sub 2}O contents calculated are thoroughly correlated with the experimental data whatever the injection carbon/oxygen ratio is. (author) 96 refs.

  6. Discrete particle simulation of bubble and slug formation in a two-dimensional gas-fluidised bed: A hard-sphere approach.

    NARCIS (Netherlands)

    Hoomans, B.P.B.; Kuipers, J.A.M.; Briels, Willem J.; van Swaaij, Willibrordus Petrus Maria

    1996-01-01

    A discrete particle model of a gas-fluidised bed has been developed and in this the two-dimensional motion of the individual, spherical particles was directly calculated from the forces acting on them, accounting for the interaction between the particles and the interstitial gas phase. Our collision

  7. Space debris: modeling and detectability

    Science.gov (United States)

    Wiedemann, C.; Lorenz, J.; Radtke, J.; Kebschull, C.; Horstmann, A.; Stoll, E.

    2017-01-01

    High precision orbit determination is required for the detection and removal of space debris. Knowledge of the distribution of debris objects in orbit is necessary for orbit determination by active or passive sensors. The results can be used to investigate the orbits on which objects of a certain size at a certain frequency can be found. The knowledge of the orbital distribution of the objects as well as their properties in accordance with sensor performance models provide the basis for estimating the expected detection rates. Comprehensive modeling of the space debris environment is required for this. This paper provides an overview of the current state of knowledge about the space debris environment. In particular non-cataloged small objects are evaluated. Furthermore, improvements concerning the update of the current space debris model are addressed. The model of the space debris environment is based on the simulation of historical events, such as fragmentations due to explosions and collisions that actually occurred in Earth orbits. The orbital distribution of debris is simulated by propagating the orbits considering all perturbing forces up to a reference epoch. The modeled object population is compared with measured data and validated. The model provides a statistical distribution of space objects, according to their size and number. This distribution is based on the correct consideration of orbital mechanics. This allows for a realistic description of the space debris environment. Subsequently, a realistic prediction can be provided concerning the question, how many pieces of debris can be expected on certain orbits. To validate the model, a software tool has been developed which allows the simulation of the observation behavior of ground-based or space-based sensors. Thus, it is possible to compare the results of published measurement data with simulated detections. This tool can also be used for the simulation of sensor measurement campaigns. It is

  8. Geomechanics of bedded salt

    International Nuclear Information System (INIS)

    Serata, S.; Milnor, S.W.

    1979-01-01

    Creep data from the literature search is reinterpreted by SGI, resulting in a better understanding of the temperature and stress state dependence of the octahedral creep rate and the octahedral shear strength. The concept of a transition strength between the elastic and the plastic states is in agreement with the data. The elastic and rheological properties of salt are described, and a set of constitutive equations is presented. The dependence of material properties on parameters such as temperature is considered. Findings on the permeability of salt are summarized, and the in-situ behavior of openings in bedded salt is described based on extensive engineering experience. A stress measuring system utilizing a finite element computer code is discussed. Geological factors affecting the stability of salt openings are considered, and the Stress Control Technique for designing stable openings in bedded salt formations is explained

  9. Problems of Small Debris

    Directory of Open Access Journals (Sweden)

    V. V. Zelentsov

    2015-01-01

    Full Text Available During the exploration of outer space (as of 1/1 2011 6853 was launched spacecraft (SC are successful 6264, representing 95% of the total number of starts. The most intensively exploited space Russia (USSR (3701 starts, 94% successful, USA (2774 starts, 90% successful, China (234 starts, 96% successful and India (89 starts, 90% successful. A small part of running the spacecraft returned to Earth (manned spacecraft and transport, and the rest remained in orbit. Some of them are descended from orbit and burned up in the atmosphere, the rest remained in the OCP and turned into space debris (SD.The composition of the Cabinet is diverse: finish the job spacecraft; boosters and the last stage of launch vehicles left in orbit after SC injection; technological waste arising during the opening drop-down structures and fragments of the destroyed spacecraft. The resulting explosion orbital SD forms ellipsoidal region which orbits blasted object. Then, as a result of precession, is the distribution of objects in orbit explosion exploding spacecraft.The whole Cabinet is divided into two factions: the observed (larger than 100 mm and not observed (less than 100 mm. Observed debris katalogalizirovan and 0.2% of the total number of SD, there was no SD is the bulk - 99.8%.SC meeting working with a fragment observed SD predictable and due to changes in altitude spacecraft avoids a possible meeting. Contact spacecraft with large fragment lead to disaster (which took place at a meeting of the Russian communications satellite "Cosmos-2251" and the American machine "Iridium". Meeting with small SD is not predictable, especially if it was formed by an explosion or collision fragments together. Orbit that KM is not predictable, and the speed can be up to 10 km / s. Meeting with small particle SD no less dangerous for the spacecraft. The impact speed of spacecraft with space debris particles can reach up to 10 ... 15 km / s at such speeds the breakdown probability thin

  10. Preliminary investigation for the development of surrogate debris from nuclear detonations in marine-urban environments

    International Nuclear Information System (INIS)

    Seybert, A.G.; Auxier II, J.D.; University of Tennessee, Knoxville, TN; Hall, H.L.; University of Tennessee, Knoxville, TN; University of Tennessee, Knoxville, TN

    2017-01-01

    Since no nuclear weapon surface detonations have occurred in urban harbor environments, the nuclear forensic community has no actual debris from which to develop and validate analytical methods for radiochemistry analysis, making the development of surrogate debris representative of this a marine-urban detonation a vital undertaking. This work seeks to build a robust model that accounts for natural and manmade environmental variations in harbor environments and vessel compositions to statistically define the elemental composition of vaporized debris from a marine-urban nuclear detonation. This initial work is necessary for follow-on neutron-activation and debris formation analysis. (author)

  11. Active Space Debris Removal System

    Directory of Open Access Journals (Sweden)

    Gabriele GUERRA

    2017-06-01

    Full Text Available Since the start of the space era, more than 5000 launches have been carried out, each carrying satellites for many disparate uses, such as Earth observation or communication. Thus, the space environment has become congested and the problem of space debris is now generating some concerns in the space community due to our long-lived belief that “space is big”. In the last few years, solutions to this problem have been proposed, one of those is Active Space Debris Removal: this method will reduce the increasing debris growth and permit future sustainable space activities. The main idea of the method proposed below is a drag augmentation system: use a system capable of putting an expanded foam on a debris which will increase the area-to-mass ratio to increase the natural atmospheric drag and solar pressure. The drag augmentation system proposed here requires a docking system; the debris will be pushed to its release height and then, after un-docking, an uncontrolled re-entry takes place ending with a burn up of the object and the foam in the atmosphere within a given time frame. The method requires an efficient way to change the orbit between two debris. The present paper analyses such a system in combination with an Electric Propulsion system, and emphasizes the choice of using two satellites to remove five effective rockets bodies debris within a year.

  12. Space Debris Mitigation CONOPS Development

    Science.gov (United States)

    2013-06-01

    literature search and review a lone article was found with any discussion of it. As with any net, the concept is to catch space debris objects in the net...travel along the track of the orbit and collect debris along its path. The lone article found contends that the idea “does not work”. Bonnal and...100,000 pieces of debris orbiting the planet , [as] NASA estimated -- 2,600 of them more than [four] inches across. [NASA] called the breakup of the

  13. NASA Orbital Debris Baseline Populations

    Science.gov (United States)

    Krisko, Paula H.; Vavrin, A. B.

    2013-01-01

    The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

  14. DebriSat Laboratory Analyses

    Science.gov (United States)

    2015-01-05

    droplets. Fluorine from Teflon wire insulation was also common in the SEM stub and witness plates deposits. Nano droplets of metallic materials...and Debris-LV debris. Aluminum was from the Al honeycomb, nadir and zenith panels, structural core and COPV liner. Aluminum oxide particles were...three pieces: Outer Nylon shell (sabot) with 2 part hollow aluminum insert. • ~600 grams, 8.6 cm diameter X 10.3 cm long – size of a soup can

  15. An Ontological Architecture for Orbital Debris Data

    OpenAIRE

    Rovetto, Robert J.

    2017-01-01

    The orbital debris problem presents an opportunity for inter-agency and international cooperation toward the mutually beneficial goals of debris prevention, mitigation, remediation, and improved space situational awareness (SSA). Achieving these goals requires sharing orbital debris and other SSA data. Toward this, I present an ontological architecture for the orbital debris domain, taking steps in the creation of an orbital debris ontology (ODO). The purpose of this ontological system is to ...

  16. The origin and distribution of HAPs elements in relation to maceral composition of the A1 lignite bed (Paleocene, Calvert Bluff Formation, Wilcox Group), Calvert mine area, east-central Texas

    Science.gov (United States)

    Crowley, Sharon S.; Warwick, Peter D.; Ruppert, Leslie F.; Pontolillo, James

    1997-01-01

    The origin and distribution of twelve potentially Hazardous Air Pollutants (HAPs; As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, and U) identified in the 1990 Clean Air Act Amendments were examined in relation to the maceral composition of the A1 bed (Paleocene, Calvert Bluff Formation, Wilcox Group) of the Calvert mine in east-central Texas. The 3.2 m-thick A1 bed was divided into nine incremental channel samples (7 lignite samples and 2 shaley coal samples) on the basis of megascopic characteristics. Results indicate that As, Cd, Cr, Ni, Pb, Sb, and U are strongly correlated with ash yield and are enriched in the shaley coal samples. We infer that these elements are associated with inorganic constituents in the coal bed and may be derived from a penecontemporaneous stream channel located several kilometers southeast of the mining block. Of the HAPs elements studied, Mn and Hg are the most poorly correlated to ash yield. We infer an organic association for Mn; Hg may be associated with pyrite. The rest of the trace elements (Be, Co, and Se) are weakly correlated with ash yield. Further analytical work is necessary to determine the mode of occurrence for these elements. Overall, concentrations of the HAPs elements are generally similar to or less than those reported in previous studies of lignites of the Wilcox Group, east-central region, Texas. Petrographic analysis indicates the following ranges in composition for the seven lignite samples: liptinites (5–8%), huminites (88–95%), and inertinites (trace amounts to 7%). Samples from the middle portion of the A1 bed contain abundant crypto-eugelinite compared to the rest of the samples; this relationship suggests that the degradation of plant material was an important process during the development of the peat mire. With the exception of Hg and Mn, relatively low levels of the HAPs elements studied are found in the samples containing abundant crypto-eugelinite. We infer that the peat-forming environment for this

  17. The physics of debris flows

    Science.gov (United States)

    Iverson, Richard M.

    1997-08-01

    Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ˜10 m³ of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate

  18. The physics of debris flows

    Science.gov (United States)

    Iverson, R.M.

    1997-01-01

    Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ???10 m3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate

  19. Numerical modelling of floating debris in the world's oceans.

    Science.gov (United States)

    Lebreton, L C-M; Greer, S D; Borrero, J C

    2012-03-01

    A global ocean circulation model is coupled to a Lagrangian particle tracking model to simulate 30 years of input, transport and accumulation of floating debris in the world ocean. Using both terrestrial and maritime inputs, the modelling results clearly show the formation of five accumulation zones in the subtropical latitudes of the major ocean basins. The relative size and concentration of each clearly illustrate the dominance of the accumulation zones in the northern hemisphere, while smaller seas surrounded by densely populated areas are also shown to have a high concentration of floating debris. We also determine the relative contribution of different source regions to the total amount of material in a particular accumulation zone. This study provides a framework for describing the transport, distribution and accumulation of floating marine debris and can be continuously updated and adapted to assess scenarios reflecting changes in the production and disposal of plastic worldwide. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Dynamics of Unusual Debris Flows on Martian Sand Dunes

    Science.gov (United States)

    Miyamoto, Hideaki; Dohm, James M.; Baker, Victor R.; Beyer, Ross A.; Bourke, Mary

    2004-01-01

    Gullies that dissect sand dunes in Russell impact crater often display debris flow-like deposits in their distal reaches. The possible range of both the rheological properties and the flow rates are estimated using a numerical simulation code of a Bingham plastic flow to help explain the formation of these features. Our simulated results are best explained by a rapid debris flow. For example, a debris flow with the viscosity of 10(exp 2) Pa s and the yield strength of 10(exp 2) Pa can form the observed deposits with a flow rate of 0.5 cu m/s sustained over several minutes and total discharged water volume on the order of hundreds of cubic meters, which may be produced by melting a surface layer of interstitial ice within the dune deposits to several centimeters depth.

  1. MIPS Observations of the Fabulous Four Debris Disks

    Science.gov (United States)

    Su, K. Y. L.; Stansberry, J. A.; Rieke, G. H.; Trilling, D. E.; Stapelfeldt, K. R.; Werner, M. W.; Beichman, C.; Chen, C.; Marengo, M.; Megeath, T.; Backman, D.; van Cleve, J.

    2004-12-01

    The Multiband Imaging Photometer for Spitzer (MIPS) provides long-wavelength capability with imaging bands at 24, 70, and 160 um. We will present the MIPS images of the Fabulous Four Debris Disks: Beta Pictoris (A5 V), Epsilon Eridani (K2 V), Fomalhaut (A3 V) and Vega (A0 V). These systems discovered by IRAS possess large far-infrared excess emission above photosphere, indicating the existence of a circumstellar dusty disk. Given the main-sequence ages of these stars ( ˜12 Myr for Beta Pictoris, ˜730 Myr for Epsilon Eridani, ˜200 Myr for Fomalhaut, and ˜350 Myr for Vega), the dust in the systems could not be primordial as it would have been removed by radiation pressure and Poynting-Robertson drag on relatively short time scales ( ˜1E4 yr). The second-generation dust in such debris disks is thought to arise primarily from collisions between planetesimals (asteroids) and from cometary activity; however, details about the debris formation and evolution are not well understood. With the sensitivity and angular resolution of the Spitizer Space Telescope, the structures of these nearby debris disks were mapped in great detail to study the disks' spatial structures at mid- to far-infrared wavelengths. These high spatial resolution images provide unprecedented new constraints on the the dust properties in the systems and limits on the origin of dusty debris. Support for this work was provided by NASA through Contract Number 960785 issued by JPL/Caltech.

  2. Space debris mitigation - engineering strategies

    Science.gov (United States)

    Taylor, E.; Hammond, M.

    The problem of space debris pollution is acknowledged to be of growing concern by space agencies, leading to recent activities in the field of space debris mitigation. A review of the current (and near-future) mitigation guidelines, handbooks, standards and licensing procedures has identified a number of areas where further work is required. In order for space debris mitigation to be implemented in spacecraft manufacture and operation, the authors suggest that debris-related criteria need to become design parameters (following the same process as applied to reliability and radiation). To meet these parameters, spacecraft manufacturers and operators will need processes (supported by design tools and databases and implementation standards). A particular aspect of debris mitigation, as compared with conventional requirements (e.g. radiation and reliability) is the current and near-future national and international regulatory framework and associated liability aspects. A framework for these implementation standards is presented, in addition to results of in-house research and development on design tools and databases (including collision avoidance in GTO and SSTO and evaluation of failure criteria on composite and aluminium structures).

  3. Circumstellar Gas in Young Planetary Debris Disks

    Science.gov (United States)

    Roberge, A.

    Circumstellar (CS) disks orbiting young stars fall into two categories: primordial disks, composed of unprocessed interstellar dust and gas, and debris disks, produced by the destruction of solid planetary bodies. In the first class, the most abundant gas is H_2; in the second, it appears that the H_2 gas has disappeared, possibly through incorporation into gas giant planets. The lifetime of H_2 gas in a CS disk is therefore of great importance, as it dictates the timescale for the formation of giant planets. FUSE observations of H_2 in CS disk systems have shown that FUV absorption spectroscopy may sensitively probe for small amounts of gas along the line of sight to the star. Most importantly, the FUSE non-detection of H_2 gas in the Beta Pictoris disk suggests that the primordial gas lifetime is less than about 12 Myr, and that gas giant planets must form very quickly. However, this suggestion is based on one system, and needs to be tested in additional systems with a range of ages, especially since there are indications that age is not the only factor in the evolution of a CS disk. We propose for FUSE observations of 3 additional debris disk systems, Fomalhaut, HD3003, and HD2884. Fomalhaut is an intermediate age debris disk, one of the Fabulous Four CS disks first discovered in 1984. The other two disks are younger, with ages similar to that of Beta Pic. All three stars are brighter in the FUV than Beta Pic, permitting us to sensitively probe for traces of H_2 gas. We will also measure the amount of secondary atomic gas produced from planetary bodies in these disks, in an effort to understand the entire evolution of CS gas in young planetary systems.

  4. Disaster Debris Recovery Database - Landfills

    Science.gov (United States)

    The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

  5. Disaster Debris Recovery Database - Recovery

    Science.gov (United States)

    The US EPA Region 5 Disaster Debris Recovery Database includes public datasets of over 6,000 composting facilities, demolition contractors, transfer stations, landfills and recycling facilities for construction and demolition materials, electronics, household hazardous waste, metals, tires, and vehicles in the states of Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, North Dakota, Ohio, Pennsylvania, South Dakota, West Virginia and Wisconsin.In this update, facilities in the 7 states that border the EPA Region 5 states were added to assist interstate disaster debris management. Also, the datasets for composters, construction and demolition recyclers, demolition contractors, and metals recyclers were verified and source information added for each record using these sources: AGC, Biocycle, BMRA, CDRA, ISRI, NDA, USCC, FEMA Debris Removal Contractor Registry, EPA Facility Registry System, and State and local listings.

  6. Marine Debris Research, Prevention, and Reduction Act

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Debris Research, Prevention, and Reduction Act legally establishes the National Oceanic and Atmospheric Administration's (NOAA) Marine Debris Program. The...

  7. The ecological impacts of marine debris

    NARCIS (Netherlands)

    Rochman, Chelsea M.; Browne, Mark Anthony; Underwood, A.J.; Franeker, Van Jan A.; Thompson, Richard C.; Amaral-Zettler, Linda A.

    2016-01-01

    Anthropogenic debris contaminates marine habitats globally, leading to several perceived ecological impacts. Here, we critically and systematically review the literature regarding impacts of debris from several scientific fields to understand the weight of evidence regarding the ecological

  8. Space Debris Elimination (SpaDE)

    Data.gov (United States)

    National Aeronautics and Space Administration — The amount of debris in low Earth orbit (LEO) has increased rapidly over the last twenty years. This prevalence of debris increases the likelihood of cascading...

  9. DebriSat Project Update and Planning

    Science.gov (United States)

    Sorge, M.; Krisko, P. H.

    2016-01-01

    DebriSat Reporting Topics: DebriSat Fragment Analysis Calendar; Near-term Fragment Extraction Strategy; Fragment Characterization and Database; HVI (High-Velocity Impact) Considerations; Requirements Document.

  10. Dryout heat flux experiments with deep heterogeneous particle bed

    International Nuclear Information System (INIS)

    Lindholm, I.; Holmstroem, S.; Miettinen, J.; Lestinen, V.; Hyvaerinen, J.; Pankakoski, P.; Sjoevall, H.

    2006-01-01

    A test facility has been constructed at Technical Research Centre of Finland (VTT) to simulate as accurately as possible the ex-vessel core particle bed in the conditions of Olkiluoto nuclear power plant. The STYX particle bed reproduces the anticipated depth of the bed and the size range of particles having irregular shape. The bed is immersed in water, creating top flooding conditions, and internally heated by an array of electrical resistance heating elements. Dryout tests have been successfully conducted at 0.1-0.7 MPa pressure for both uniformly mixed and stratified bed geometries. In all tests, including the stratified ones, the dry zone first formed near the bottom of the bed. The measured dryout heat fluxes increased with increasing pressure, from 232 kW/m 2 at near atmospheric pressure to 451 kW/m 2 at 0.7 MPa pressure. The data show some scatter even for the uniform bed. The tests with the stratified bed indicate a clear reduction of critical power due to the presence of a layer of small particles on top of the uniform bed. Comparison of data with various critical power (dryout heat flux) correlations for porous media shows that the most important parameter in the models is the effective particle diameter. Adiabatic debris bed flow resistance measurements were conducted to determine the most representative particle diameter. This diameter is close, but not equal, to the particle number-weighted average diameter of the bed material. With it, uniform bed data can be calculated to within an accuracy of 3-28% using Lipinski's 0-D model. In the stratified bed experiments, it appears that the top layer was partially fluidized, hence the measured critical power was significantly higher than calculated. Future experiments are being planned with denser top layer material to eliminate non-prototypic fluidization

  11. DebriSat Hypervelocity Impact Test

    Science.gov (United States)

    2015-08-01

    public release; distribution unlimited.  Targets: Scaled Multishock Shield, DebrisLV, and DebriSat  500-600 g hollow aluminum and nylon projectile... insulation . DebriSat’s internal components were structurally similar to real flight hardware but were nonfunctional. AEDC-TR-15-S-2 6...structures with an AL 5052 honeycomb core and M55J carbon fiber face sheets. The basic system characteristics of the DebriSat are given in Table 1

  12. Coolability of volumetrically heated particle beds

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Muhammad

    2017-03-22

    In case of a severe nuclear reactor accident, with loss of coolant, a particle bed may be formed from the fragmentation of the molten core in the residual water at different stages of the accident. To avoid further propagation of the accident and maintain the integrity of the reactor pressure vessel, the decay heat of the particle bed must be removed. To better understand the various thermo-hydraulic processes within such heat-generating particle beds, the existing DEBRIS test facility at IKE has been modified to be able to perform novel boiling, dryout and quenching experiments. The essential experimental data includes the pressure gradients measured by 8 differential pressure transducers along the bed height as a function of liquid and vapour superficial velocities, the determination of local dryout heat fluxes for different system pressures as well as the local temperature distribution measured by a set of 51 thermocouples installed inside the particle bed. The experiments were carried out for two different particle beds: a polydispersed particle bed which consisted of stainless steel balls (2 mm, 3 mm and 6 mm diameters) and an irregular particle bed which consisted of a mixture of steel balls (3 mm and 6 mm) and irregularly shaped Al{sub 2}O{sub 3} particles. Additionally, all experiments were carried out for different flow conditions, such as the reference case of passive 1D top-flooding, 1D bottom flooding (driven by external pumps and different downcomer configurations) and 2D top-/bottom-/lateral flooding with a perforated downcomer. In this work, it has been observed that for both particle beds with downcomer configurations an open downcomer leads to the best coolability (dryout heat flux = 1560 kW/m{sup 2}, polydispersed particle bed, psys = 1 bar) of the particle bed, mainly due to bottom-flow with enhanced natural convection. It has also been shown that a potential lateral flow via a perforation of the downcomer does not bring any further improvements

  13. Coolability of volumetrically heated particle beds

    International Nuclear Information System (INIS)

    Rashid, Muhammad

    2017-01-01

    In case of a severe nuclear reactor accident, with loss of coolant, a particle bed may be formed from the fragmentation of the molten core in the residual water at different stages of the accident. To avoid further propagation of the accident and maintain the integrity of the reactor pressure vessel, the decay heat of the particle bed must be removed. To better understand the various thermo-hydraulic processes within such heat-generating particle beds, the existing DEBRIS test facility at IKE has been modified to be able to perform novel boiling, dryout and quenching experiments. The essential experimental data includes the pressure gradients measured by 8 differential pressure transducers along the bed height as a function of liquid and vapour superficial velocities, the determination of local dryout heat fluxes for different system pressures as well as the local temperature distribution measured by a set of 51 thermocouples installed inside the particle bed. The experiments were carried out for two different particle beds: a polydispersed particle bed which consisted of stainless steel balls (2 mm, 3 mm and 6 mm diameters) and an irregular particle bed which consisted of a mixture of steel balls (3 mm and 6 mm) and irregularly shaped Al 2 O 3 particles. Additionally, all experiments were carried out for different flow conditions, such as the reference case of passive 1D top-flooding, 1D bottom flooding (driven by external pumps and different downcomer configurations) and 2D top-/bottom-/lateral flooding with a perforated downcomer. In this work, it has been observed that for both particle beds with downcomer configurations an open downcomer leads to the best coolability (dryout heat flux = 1560 kW/m 2 , polydispersed particle bed, psys = 1 bar) of the particle bed, mainly due to bottom-flow with enhanced natural convection. It has also been shown that a potential lateral flow via a perforation of the downcomer does not bring any further improvements in

  14. Alcoholic fermentation process and methane formation unit with biomass in fixed bed; Processo de fermentacao alcoolica e fermentador de metanizacao com biomassa em leito fixo

    Energy Technology Data Exchange (ETDEWEB)

    Camilleri, Claude [Societe Generale de Techniques Nouvelles (France)

    1986-01-01

    The pollution, measured from Biochemical Oxygen Demand, is constituted primary of organic carbon. The pollution abatement is made traditionally by thr reduction of this carbon by an aerobic way. Were made some tries in order to recover this carbon as an energy source and the methane formation process arises like the most attractive alternative 2 figs.

  15. Vision-based Ground Test for Active Debris Removal

    Directory of Open Access Journals (Sweden)

    Seong-Min Lim

    2013-12-01

    Full Text Available Due to the continuous space development by mankind, the number of space objects including space debris in orbits around the Earth has increased, and accordingly, difficulties of space development and activities are expected in the near future. In this study, among the stages for space debris removal, the implementation of a vision-based approach technique for approaching space debris from a far-range rendezvous state to a proximity state, and the ground test performance results were described. For the vision-based object tracking, the CAM-shift algorithm with high speed and strong performance, and the Kalman filter were combined and utilized. For measuring the distance to a tracking object, a stereo camera was used. For the construction of a low-cost space environment simulation test bed, a sun simulator was used, and in the case of the platform for approaching, a two-dimensional mobile robot was used. The tracking status was examined while changing the position of the sun simulator, and the results indicated that the CAM-shift showed a tracking rate of about 87% and the relative distance could be measured down to 0.9 m. In addition, considerations for future space environment simulation tests were proposed.

  16. Photometric Studies of GEO Debris

    Science.gov (United States)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Edwin; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the SMARTS (Small and Medium Aperture Research Telescope System) 0.9-m at CTIO for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? In this paper we report on the photometric results. For a sample of 50 objects, more than 90 calibrated sequences of R-B-V-I-R magnitudes have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus

  17. Young Debris Disks With Newly Discovered Emission Features

    Science.gov (United States)

    Ballering, N.

    2014-04-01

    We analyzed the Spitzer/IRS spectra of young A and F stars that host debris disks with previously unidentified silicate emission features. Such features probe small, warm dust grains in the inner regions of these young systems where terrestrial planet formation may be proceeding (Lisse et al. 2009). For most systems, these regions are too near their host star to be directly seen with high-contrast imaging and too warm to be imaged with submillimeter interferometers. Mid-infrared excess spectra - originating from the thermal emission of the debris disk dust - remain the best data to constrain the properties of the debris in these regions. For each target, we fit physically-motivated model spectra to the data. Typical spectra of unresolved debris disks are featureless and suffer severe degeneracies between the dust location and the grain properties; however, spectra with solid-state emission features provide significantly more information, allowing for a more accurate determination of the dust size, composition, and location (e.g. Chen et al. 2006; Olofsson et al. 2012). Our results shed light on the dynamic properties occurring in the terrestrial regions of these systems. For instance, the sizes of the smallest grains and the nature of the grain size distribution reveal whether the dust originates from steady-state collisional cascades or from stochastic collisions. The properties of the dust grains - such as their crystalline or amorphous structure - can inform us of grain processing mechanisms in the disk. The location of this debris illuminates where terrestrial planet forming activity is occurring. We used results from the Beta Pictoris - which has a well-resolved debris disk with emission features (Li et al. 2012) - to place our results in context. References: Chen et al. 2006, ApJS, 166, 351 Li et al. 2012, ApJ, 759, 81 Lisse et al. 2009, ApJ, 701, 2019 Olofsson et al. 2012, A&A, 542, A90

  18. National waste terminal storage repository in a bedded salt formation for spent unreprocessed fuel. Special study No. 1. 25-year retrievability

    International Nuclear Information System (INIS)

    1978-12-01

    National Waste Terminal Storage Repository 2 (NWTSR2), in bedded salt, for spent unreprocessed fuel is the subject of a conceptual design project which began in January 1977. In the base conceptual design the spent fuel is to be stored in a retrievable mode for 5 years. This report presents the results of a separate study on 25-year retrievability with open storage rooms. Drawings prepared for 25-year retrievability are only those which differ from the companion 5-year retrievability drawings which comprise Volume II of the Conceptual Design Report (CDR). NWTSR2 capital facilities originally were to be constructed in phases. Phase I was to include those facilities required for the first 5 years of operation, which were hypothesized to be from 1985 through 1990; Phase II was to include facilities required from 1991 until the capacity of the 2000-acre mine was reached. These dates are used as the basis for conceptual design and for Special Study No. 1 but do not represent actual schedule dates for the repository. The terms Phase I and Phase II are used throughout the drawings and test, so they need to be understood. However, it is not now intended to phase the capital construction because of the relatively small effort represented by Phase II surface construction. An optional future expansion of the mine, Phase III, would add 1000 acres on the end of the mine opposite the shaft pillar. The optional Phase III expansion would commence operation upon completion of Phase II operations. The drawings and design comparisons for Phase III mine operations appear only in this report

  19. Erosion and deposition on a debris-flow fan

    Science.gov (United States)

    Densmore, A. L.; Schuerch, P.; Rosser, N. J.; McArdell, B. W.

    2011-12-01

    The ability of a debris flow to entrain or deposit sediment controls the downstream evolution of flow volume, and ultimately dictates both the geomorphic impact of the flow and the potential hazard that it represents. Our understanding of the patterns of, and controls on, such flow volume changes remains extremely limited, however, partly due to a poor mechanistic grasp of the interactions between debris flows and their bed and banks. In addition, we lack a good understanding of the cumulative long-term effects of sequences of flows in a single catchment-fan system. Here we begin to address these issues by using repeated terrestrial laser scanning (TLS) to characterize the detailed surface change associated with the passage of multiple debris flows on the Illgraben fan, Switzerland. We calculate surface elevation change along a 300 m study reach, and from this derive the downfan rate of flow volume change, or lag rate; for comparison, we also derive the spatially-averaged lag rate over the entire ~2 km length of the fan. Lag rates are broadly comparable over both length scales, indicating that flow behavior does not vary significantly across the fan for most flows, but importantly we find that flow volume at the fan head is a poor predictor of volume at the fan toe. The sign and magnitude of bed elevation change scale with local flow depth; at flow depths 2 m. On the Illgraben fan, this depth corresponds to a basal shear stress of 3-4 kPa. Because flow depth is in part a function of channel cross-sectional topography, which varies strongly both within and between flows, this result indicates that erosion and deposition are likely to be highly dynamic. The dependence of flow volume change on both the channel topography and the flow history may thus complicate efforts to predict debris-flow inundation areas by simple flow routing. We then apply a 2d numerical model of debris-flow fan evolution to explore the key controls on debris-flow routing and topographic

  20. Debris-flows scale predictions based on basin spatial parameters calculated from Remote Sensing images in Wenchuan earthquake area

    International Nuclear Information System (INIS)

    Zhang, Huaizhen; Chi, Tianhe; Liu, Tianyue; Wang, Wei; Yang, Lina; Zhao, Yuan; Shao, Jing; Yao, Xiaojing; Fan, Jianrong

    2014-01-01

    Debris flow is a common hazard in the Wenchuan earthquake area. Collapse and Landslide Regions (CLR), caused by earthquakes, could be located from Remote Sensing images. CLR are the direct material source regions for debris flow. The Spatial Distribution of Collapse and Landslide Regions (SDCLR) strongly impact debris-flow formation. In order to depict SDCLR, we referred to Strahler's Hypsometric analysis method and developed 3 functional models to depict SDCLR quantitatively. These models mainly depict SDCLR relative to altitude, basin mouth and main gullies of debris flow. We used the integral of functions as the spatial parameters of SDCLR and these parameters were employed during the process of debris-flows scale predictions. Grouping-occurring debris-flows triggered by the rainstorm, which occurred on September 24th 2008 in Beichuan County, Sichuan province China, were selected to build the empirical equations for debris-flows scale predictions. Given the existing data, only debris-flows runout zone parameters (Max. runout distance L and Lateral width B) were estimated in this paper. The results indicate that the predicted results were more accurate when the spatial parameters were used. Accordingly, we suggest spatial parameters of SDCLR should be considered in the process of debris-flows scale prediction and proposed several strategies to prevent debris flow in the future

  1. Disaster Characteristics and Mitigation Measures of Huge Glacial Debris Flows along the Sichuan-Tibet Railway

    Science.gov (United States)

    Liu, Jinfeng; You, Yong; Zhang, Guangze; Wang, Dong; Chen, Jiangang; Chen, Huayong

    2017-04-01

    accumulation length is 1.91 km and 1.75 km, and the accumulation width is 4.71 km and 3.68 km for the case of P=0.5% and P=1% respectively. The accumulation depth along the main flow direction is 40˜60m and 25˜35m. Consequently, four plans of railway alignment including passing through the down-stream by tunnel, passing through the gully outlet by tunnel and bridge, passing through the middle-lower part of the accumulation fan by railway bed and bridge, passing through the middle-lower part of the accumulation fan by tunnel were presented. The four plans were compared and related debris flow mitigation measures were provided.

  2. Detecting debris flows using ground vibrations

    Science.gov (United States)

    LaHusen, Richard G.

    1998-01-01

    Debris flows are rapidly flowing mixtures of rock debris, mud, and water that originate on steep slopes. During and following volcanic eruptions, debris flows are among the most destructive and persistent hazards. Debris flows threaten lives and property not only on volcanoes but far downstream in valleys that drain volcanoes where they arrive suddenly and inundate entire valley bottoms. Debris flows can destroy vegetation and structures in their path, including bridges and buildings. Their deposits can cover roads and railways, smother crops, and fill stream channels, thereby reducing their flood-carrying capacity and navigability.

  3. Glacier beds that will be exposed in the future: How will geomorphologic and hydrologic processes develop?

    Science.gov (United States)

    Linsbauer, Andreas; Paul, Frank; Haeberli, Wilfried

    2014-05-01

    The rapid shrinkage of glaciers in the Alps has widespread impacts on relief development and hydrology. Slope failures, collapse of lateral moraines, loose debris in glacier fore-fields, new lakes and changing river beds are among the most visible impacts. They already require increased attention by tourists, monitoring by local authorities and mitigation measures (e.g. www.gletschersee.ch). A view into potential future developments (after glaciers have disappeared) is thus of high interest. With recently developed models that reconstruct glacier bed topography from easily available datasets (e.g. glacier outlines and a DEM) over entire mountain ranges, potential developments of the landscape and hydrology can be quantitatively determined. The modelled glacier beds - though they must be seen as a rough first order approximation only - also allows the investigation of a wide range of glaciological relations and dependencies that have been widely applied but were never investigated for a large sample of glaciers so far. A key reason is that information on glacier thickness distribution and total ice volume is sparse and that the future development of glaciers can only be modelled realistically when a glacier bed is available. Hence, with the glacier beds now available there is a larger number of geomorphological, glaciological and hydrological studies ahead of us. This presentation is providing an overview on the lessons learned about glaciers and their future development from the modelled glacier beds, the expected changes in hydrology (e.g. decreasing glacier volume and formation of new lakes) and potential impacts from the altered geomorphology (e.g. debuttressing of rock walls). In particular the flat tongues of larger valley glaciers are rather thick and leave oversteepened lateral moraines or rock walls behind, towering above overdeepenings in the glacier bed that might be filled with water. It is thus expected that the hazard potential will further increase in

  4. Coupled prediction of flash flood response and debris flow occurrence: Application on an alpine extreme flood event

    Science.gov (United States)

    Destro, Elisa; Amponsah, William; Nikolopoulos, Efthymios I.; Marchi, Lorenzo; Marra, Francesco; Zoccatelli, Davide; Borga, Marco

    2018-03-01

    The concurrence of flash floods and debris flows is of particular concern, because it may amplify the hazard corresponding to the individual generative processes. This paper presents a coupled modelling framework for the predictions of flash flood response and of the occurrence of debris flows initiated by channel bed mobilization. The framework combines a spatially distributed flash flood response model and a debris flow initiation model to define a threshold value for the peak flow which permits identification of channelized debris flow initiation. The threshold is defined over the channel network as a function of the upslope area and of the local channel bed slope, and it is based on assumptions concerning the properties of the channel bed material and of the morphology of the channel network. The model is validated using data from an extreme rainstorm that impacted the 140 km2 Vizze basin in the Eastern Italian Alps on August 4-5, 2012. The results show that the proposed methodology has improved skill in identifying the catchments where debris-flows are triggered, compared to the use of simpler thresholds based on rainfall properties.

  5. Practice Hospital Bed Safety

    Science.gov (United States)

    ... Home For Consumers Consumer Updates Practice Hospital Bed Safety Share Tweet Linkedin Pin it More sharing options ... It depends on the complexity of the bed." Safety Tips CDRH offers the following safety tips for ...

  6. Bed Bugs and Schools

    Science.gov (United States)

    Bed bugs have long been a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. They are successful hitchhikers, and can move from an infested site to furniture, bedding, baggage, boxes, and clothing.

  7. Colisional Cloud Debris and Propelled Evasive Maneuvers

    Science.gov (United States)

    Ferreira, L. S.; Jesus, A. D. C.; Carvalho, T. C. F.; Sousa, R. R.

    2017-10-01

    Space debris clouds exist at various altitudes in the environment outside the Earth. Fragmentation of debris and/or collision between the debris of a cloud increases the amount of debris, producing smaller debris. This event also increases significantly the chances of collision with operational vehicles in orbit. In this work we study clouds of debris that are close to a spacecraft in relation to its distance from the center of the Earth. The results show several layers of colliding debris depending on their size over time of evasive maneuvers of the vehicle. In addition, we have tested such maneuvers for propulsion systems with a linear and exponential mass variation model. The results show that the linear propulsion system is more efficient.

  8. Space Tourism: Orbital Debris Considerations

    Science.gov (United States)

    Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

    2002-01-01

    Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a

  9. Taphonomy of the vertebrate bone beds from the Klūnas fossil site, Upper Devonian Tērvete Formation of Latvia

    Directory of Open Access Journals (Sweden)

    Jeļena Vasiļkova

    2012-05-01

    Full Text Available Combined sedimentological and taphonomical study of the siliciclastic sequence of the Tērvete Formation in the stratotypical area was aimed at revealing the formation of the three oryctocoenoses discovered and related structural and textural features of the deposits, as well as at detailed observation of the taphonomical peculiarities of the obtained palaeontological material. The fossil vertebrate assemblage is represented by 14 taxa comprising placoderms, acanthodians, sarcopterygians and actinopterygians. The three oryctocoenoses, first recognized in 2010, differ in the proportions of repeatedly buried material, in the number and degree of preservation of small and fragile skeletal elements, as well as in the evaluated current velocity and the transportation distance. Sedimentary concentrations of marine vertebrate remains, dominated by the antiarchs Bothriolepis ornata and B. jani, have been formed under the influence of fluvial and tidal processes in the shallow-water environment, deltaic or estuarine settings. Elongated placoderm and sarcopterygian bones are probably better indicators of the palaeoflow direction than acanthodian spines or sarcopterygian teeth.

  10. Dips, ramps, and rolls- Evidence for paleotopographic and syn-depositional fault control on the Western Kentucky No. 4 coal bed, tradewater formation (Bolsovian) Illinois Basin

    Science.gov (United States)

    Greb, S.F.; Eble, C.F.; Williams, D.A.; Nelson, W.J.

    2001-01-01

    The Western Kentucky No. 4 coal is a high-volatile B to high-volatile C bituminous coal that has been heavily mined along the southern margin of the Western Kentucky Coal Field. The seam has a reputation for rolling floor elevation. Elongate trends of floor depressions are referred to as "dips" and "rolls" by miners. Some are relatively narrow and straight to slightly curvilinear in plan view, with generally symmetric to slightly asymmetric cross-sections. Others are broader and asymmetric in section, with sharp dips on one limb and gradual, ramp-like dips on the other. Some limbs change laterally from gradual dip, to sharp dip, to offset of the coal. Lateral changes in the rate of floor elevation dip are often associated with changes in coal thickness, and in underground mines, changes in floor elevation are sometimes associated with roof falls and haulage problems. In order to test if coal thickness changes within floor depressions were associated with changes in palynology, petrography and coal quality, the coal was sampled at a surface mine across a broad. ramp-like depression that showed down-dip coal thickening. Increment samples of coal from a thick (150 cm), down-ramp and thinner (127 cm), up-ramp position at one surface mine correlate well between sample sites (a distance of 60 m) except for a single increment. The anomalous increment (31 cm) in the lower-middle part of the thick coal bed contained 20% more Lycospora orbicula spores. The rolling floor elevations noted in the study mines are inferred to have been formed as a result of pre-peat paleotopographic depressions, syn-depositional faulting, fault-controlled pre-peat paleotopography, and from compaction beneath post-depositional channels and slumps. Although the association of thick coal with linear trends and inferred faults has been used in other basins to infer syn-depositional faulting, changes in palynology within increment samples of the seam along a structural ramp in this study provide

  11. In-vessel core debris retention experiments. Final report

    International Nuclear Information System (INIS)

    1998-10-01

    The in-vessel cooling experimental program (Phase 1 and 2) was motivated by the survivability of the TMI lower vessel head during the TMI-2 accident. During that accident, molten debris relocation into the water filled lower head resulted in a localized hot spot in the lower head, but no lower head failure occurred. A postulated set of mechanisms which could be involved in and responsible for the survivability of the TMI lower head were identified and experimentally investigated as part of this program. These mechanisms included: the formation of a gap (contact resistance) between the relocated and frozen debris and the vessel wall was a key aspect of the in-vessel cooling mechanism; wall heatup due to the relocated debris in the presence of wall stress due to a pressure gradient across the vessel wall; gap growth due to a lack of debris adherence to the vessel wall and material creep of the heated vessel wall; and the potential for enhanced wall cooling due to gap growth. Each of these postulated mechanisms was investigated in this experimental program. This report summarizes the several insights and conclusions that were obtained from this experimental program. This report documents the entire set of five experiments completed in Phase 2 of this experimental program. Results from the Phase 1 effort were used to plan and select the Phase 2 test matrix. Conclusions from the Phase 1 and 2 experiments are identified and recommendations for future work are provided

  12. Warm Debris Disks from WISE

    Science.gov (United States)

    Padgett, Deborah L.

    2011-01-01

    "The Wide Field Infrared Survey Explorer (WISE) has just completed a sensitive all-sky survey in photometric bands at 3.4, 4.6, 12, and 22 microns. We report on a preliminary investigation of main sequence Hipparcos and Tycho catalog stars with 22 micron emission in excess of photospheric levels. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets and is preferentially found in young systems with ages warm debris disk candidates are detected among FGK stars and a similar number of A stars within 120 pc. We are in the process of obtaining spectra to determine spectral types and activity level of these stars and are using HST, Herschel and Keck to characterize the dust, multiplicity, and substellar companions of these systems. In this contribution, we will discuss source selection methods and individual examples from among the WISE debris disk candidates. "

  13. Space Debris and Observational Astronomy

    Science.gov (United States)

    Seitzer, Patrick

    2018-01-01

    Since the launch of Sputnik 1 in 1957, astronomers have faced an increasing number of artificial objects contaminating their images of the night sky. Currently almost 17000 objects larger than 10 cm are tracked and have current orbits in the public catalog. Active missions are only a small fraction of these objects. Most are inactive satellites, rocket bodies, and fragments of larger objects: all space debris. Several mega-constellations are planned which will increase this number by 20% or more in low Earth orbit (LEO). In terms of observational astronomy, this population of Earth orbiting objects has three implications: 1) the number of streaks and glints from spacecraft will only increase. There are some practical steps that can be taken to minimize the number of such streaks and glints in astronomical imaging data. 2) The risk to damage to orbiting astronomical telescopes will only increase, particularly those in LEO. 3) If you are working on a plan for an orbiting telescope project, then there are specific steps that must be taken to minimize space debris generation during the mission lifetime, and actions to safely dispose of the spacecraft at end of mission to prevent it from becoming space debris and a risk to other missions. These steps may involve sacrifices to mission performance and lifetime, but are essential in today's orbital environment.

  14. Field and flume investigations of the effects of logjams and woody debris on streambed morphology

    Science.gov (United States)

    Leung, V.; Montgomery, D. R.; McHenry, M. L.

    2014-12-01

    Interactions among wood debris, fluid flow and sediment transport in rivers are first-order controls on channel morphodynamics, affecting streambed morphology, sediment transport, sediment storage and aquatic habitat. Woody debris increases the hydraulic and topographic complexity in rivers, leading to a greater diversity of aquatic habitats and an increase in the number of large pools that are important fish habitat and breeding grounds. In the past decade, engineered logjams have become an increasingly used tool in river management for simultaneously decreasing the rate of riverbank migration and improving aquatic habitat. Sediment deposits around woody debris build up riverbanks and counteract bank migration caused by erosion. Previous experiments on flow visualization around model woody debris suggest the amount of sediment scour and deposition are primarily related to the presence of roots and the obstructional area of the woody debris. We present the results of fieldwork and sediment transport experiments of streambed morphology around stationary woody debris. Field surveys on the Hoh River and the Elwha River, WA, measure the local streambed morphology around logjams and individual pieces of woody debris. We quantified the amount of local scour and dam-removal related fine sediment deposition around natural and engineered logjams of varying sizes and construction styles, located in different geomorphic settings. We also quantified the amount of local scour around individual pieces of woody debris of varying sizes, geometries and orientations relative to flow. The flume experiments tested the effects of root geometry and log orientation of individual stationary trees on streambed morphology. The flume contained a deformable sediment bed of medium sand. We find that: 1) the presence of roots on woody debris leads to greater areas of both sediment scour and deposition; and 2) the amount of sediment scour and deposition are related to the wood debris cross

  15. Wildfire impacts on the processes that generate debris flows in burned watersheds

    Science.gov (United States)

    Parise, M.; Cannon, S.H.

    2012-01-01

    Every year, and in many countries worldwide, wildfires cause significant damage and economic losses due to both the direct effects of the fires and the subsequent accelerated runoff, erosion, and debris flow. Wildfires can have profound effects on the hydrologic response of watersheds by changing the infiltration characteristics and erodibility of the soil, which leads to decreased rainfall infiltration, significantly increased overland flow and runoff in channels, and movement of soil. Debris-flow activity is among the most destructive consequences of these changes, often causing extensive damage to human infrastructure. Data from the Mediterranean area and Western United States of America help identify the primary processes that result in debris flows in recently burned areas. Two primary processes for the initiation of fire-related debris flows have been so far identified: (1) runoff-dominated erosion by surface overland flow; and (2) infiltration-triggered failure and mobilization of a discrete landslide mass. The first process is frequently documented immediately post-fire and leads to the generation of debris flows through progressive bulking of storm runoff with sediment eroded from the hillslopes and channels. As sediment is incorporated into water, runoff can convert to debris flow. The conversion to debris flow may be observed at a position within a drainage network that appears to be controlled by threshold values of upslope contributing area and its gradient. At these locations, sufficient eroded material has been incorporated, relative to the volume of contributing surface runoff, to generate debris flows. Debris flows have also been generated from burned basins in response to increased runoff by water cascading over a steep, bedrock cliff, and incorporating material from readily erodible colluvium or channel bed. Post-fire debris flows have also been generated by infiltration-triggered landslide failures which then mobilize into debris flows. However

  16. Combustion studies in a fluidised bed-The link between temperature, NO{sub x} and N{sub 2}O formation, char morphology and coal type

    Energy Technology Data Exchange (ETDEWEB)

    Valentim, B.; Lemos de Sousa, M.J. [Centro de Geologia da Universidade do Porto, Faculdade de Ciencias, Praca de Gomes Teixeira, 4099-002, Porto (Portugal); Abelha, P.; Boavida, D.; Gulyurtlu, I. [Departamento de Engenharia Energetica e Controlo Ambiental (DEECA), Instituto Nacional de Engenharia, Tecnologia e Inovacao (INETI), Estrada do Paco do Lumiar, 22, Edif. J, 1649-038, Lisboa (Portugal)

    2006-06-06

    Five commercially available high volatile bituminous coals from different origins were studied with the objective of characterizing their petrographic nature with respect to emissions of NO{sub x} and N{sub 2}O. The chars produced [at temperatures ranging from 700 to 1000 {sup o}C] from these coals were also petrographic ally analyzed to assess the contribution of char to NO{sub x} and N{sub 2}O formation during combustion. Vitrinite-rich coals produced higher porous chars (cenospheres and tenuinetworks) than those that are rich in inertinite. The former coals were, however, found to release lower concentrations of NO. Consistent with previous works, N{sub 2}O emissions were observed to decrease significantly with temperature, however, on the whole, the N{sub 2}O emissions from vitrinite-rich high volatile coals were less than those from inertinite-rich coals. Additionally, high porous chars were found to give rise to lower emissions of NO and N{sub 2}O. (author)

  17. Effects of episodic sediment supply on bedload transport rate in mountain rivers. Detecting debris flow activity using continuous monitoring

    Science.gov (United States)

    Uchida, Taro; Sakurai, Wataru; Iuchi, Takuma; Izumiyama, Hiroaki; Borgatti, Lisa; Marcato, Gianluca; Pasuto, Alessandro

    2018-04-01

    Monitoring of sediment transport from hillslopes to channel networks as a consequence of floods with suspended and bedload transport, hyperconcentrated flows, debris and mud flows is essential not only for scientific issues, but also for prevention and mitigation of natural disasters, i.e. for hazard assessment, land use planning and design of torrent control interventions. In steep, potentially unstable terrains, ground-based continuous monitoring of hillslope and hydrological processes is still highly localized and expensive, especially in terms of manpower. In recent years, new seismic and acoustic methods have been developed for continuous bedload monitoring in mountain rivers. Since downstream bedload transport rate is controlled by upstream sediment supply from tributary channels and bed-external sources, continuous bedload monitoring might be an effective tool for detecting the sediments mobilized by debris flow processes in the upper catchment and thus represent an indirect method to monitor slope instability processes at the catchment scale. However, there is poor information about the effects of episodic sediment supply from upstream bed-external sources on downstream bedload transport rate at a single flood time scale. We have examined the effects of sediment supply due to upstream debris flow events on downstream bedload transport rate along the Yotagiri River, central Japan. To do this, we have conducted continuous bedload observations using a hydrophone (Japanese pipe microphone) located 6.4 km downstream the lower end of a tributary affected by debris flows. Two debris flows occurred during the two-years-long observation period. As expected, bedload transport rate for a given flow depth showed to be larger after storms triggering debris flows. That is, although the magnitude of sediment supply from debris flows is not large, their effect on bedload is propagating >6 km downstream at a single flood time scale. This indicates that continuous bedload

  18. RELATION BETWEEN PRECIPITATION AND INITIATION OF DEBRIS FLOWS IN THE JIANGJIA RAVINE,YUNNAN PROVINCE, SOUTHWEST CHINA

    Institute of Scientific and Technical Information of China (English)

    Zili FENG; Peng CUI; Xiaoqing CHEN; Jie CHEN

    2006-01-01

    In the Jiangjia Ravine, debris flows are often triggered by short-duration rainstorms frequently. To reveal the unique initiation process of debris flows, rainfall and debris flow initiation in an upstream area was continually observed. It is concluded that flash floods resulting from short-duration rainstorms play a key role in the initiation of debris flows. Surface runoff forms flash floods due to special topographic conditions. The flash floods mobilize the sediment deposits in the upper section of the branch gullies,hence, high density viscous debris flows initiate. The initiation of debris flows in the Jiangjia Ravine has a close relation with precipitation. Applying the Takahashi model of debris flow initiation, it is concluded that: to mobilize cohesive deposits in the gully bed the depth of flash floods must exceed a critical depth. This critical depth of floods makes the definition of thresholds of rainfall intensity possible. Considering the change in the initial infiltration rate at different initial water content of bank slopes, and the influence of antecedent precipitation on the initial water content, the relation between the thresholds of rainfall intensity and the antecedent precipitation show good agreement with the empirical relation established by previous research.

  19. Study on recriticality of fuel debris during hypothetical severe accidents in the Advanced Neutron Source reactor

    International Nuclear Information System (INIS)

    Kim, S.H.; Taleyarkhan, R.P.; Georgevich, V.; Navarro-Valenti, S.; Shin, S.T.

    1995-09-01

    A study has been performed to measure the potential of recriticality during hypothetical severe accident in Advanced Neutron Source (ANS). For the lumped debris configuration in the Reactor Coolant System (RCS), as found in the previous study, recriticality potential may be very low. However, if fuel debris is dispersed and mixed with heavy water in RCS, recriticality potential has been predicted to be substantial depending on thermal-hydraulic conditions surrounding fuel debris mixture. The recriticality potential in RCS is substantially reduced for the three element core design with 50% enrichment. Also, as observed in the previous study, strong dependencies of k eff on key thermal hydraulic parameters are shown. Light water contamination is shown to provide a positive reactivity, and void formation due to boiling of mixed water provides enough negative reactivity and to bring the system down to subcritical. For criticality potential in the subpile room, the lumped debris configuration does not pose a concern. Dispersed configuration in light water pool of the subpile room is also unlikely to result in criticality. However, if the debris is dispersed in the pool that is mixed with heavy water, the results indicate that a substantial potential exists for the debris to reach the criticality. However, if prompt recriticality disperses the debris completely in the subpile room pool, subsequent recriticality may be prevented since neutron leakage effects become large enough

  20. The formation of ice sails

    Science.gov (United States)

    Fowler, A. C.; Mayer, C.

    2017-11-01

    Debris-covered glaciers are prone to the formation of a number of supraglacial geomorphological features, and generally speaking, their upper surfaces are far from level surfaces. Some of these features are due to radiation screening or enhancing properties of the debris cover, but theoretical explanations of the consequent surface forms are in their infancy. In this paper we consider a theoretical model for the formation of "ice sails", which are regularly spaced bare ice features which are found on debris-covered glaciers in the Karakoram.

  1. Small satellites and space debris issues

    Science.gov (United States)

    Yakovlev, M.; Kulik, S.; Agapov, V.

    2001-10-01

    The objective of this report is the analysis of the tendencies in designing of small satellites (SS) and the effect of small satellites on space debris population. It is shown that SS to include nano- and pico-satellites should be considered as a particularly dangerous source of space debris when elaborating international standards and legal documents concerning the space debris problem, in particular "International Space Debris Mitigation Standard". These issues are in accordance with the IADC goals in its main activity areas and should be carefully considered within the IADC framework.

  2. Models and correlations of the DEBRIS Late-Phase Melt Progression Model

    International Nuclear Information System (INIS)

    Schmidt, R.C.; Gasser, R.D.

    1997-09-01

    The DEBRIS Late Phase Melt Progression Model is an assembly of models, embodied in a computer code, which is designed to treat late-phase melt progression in dry rubble (or debris) regions that can form as a consequence of a severe core uncover accident in a commercial light water nuclear reactor. The approach is fully two-dimensional, and incorporates a porous medium modeling framework together with conservation and constitutive relationships to simulate the time-dependent evolution of such regions as various physical processes act upon the materials. The objective of the code is to accurately model these processes so that the late-phase melt progression that would occur in different hypothetical severe nuclear reactor accidents can be better understood and characterized. In this report the models and correlations incorporated and used within the current version of DEBRIS are described. These include the global conservation equations solved, heat transfer and fission heating models, melting and refreezing models (including material interactions), liquid and solid relocation models, gas flow and pressure field models, and the temperature and compositionally dependent material properties employed. The specific models described here have been used in the experiment design analysis of the Phebus FPT-4 debris-bed fission-product release experiment. An earlier DEBRIS code version was used to analyze the MP-1 and MP-2 late-phase melt progression experiments conducted at Sandia National Laboratories for the US Nuclear Regulatory Commission

  3. The influence of basal-ice debris on patterns and rates of glacial erosion

    Science.gov (United States)

    Ugelvig, Sofie V.; Egholm, David L.

    2018-05-01

    Glaciers have played a key role for shaping much of Earth's high topography during the cold periods of the Late Cenozoic. However, despite of their distinct influence on landscapes, the mechanisms of glacial erosion, and the properties that determine their rate of operation, are still poorly understood. Theoretical models of subglacial erosion generally highlight the influence of basal sliding in setting the pace of erosion, but they also point to a strong influence of other subglacial properties, such as effective bed pressure and basal-ice debris concentration. The latter properties are, however, not easily measured in existing glaciers, and hence their influence cannot readily be confirmed by observations. In order to better connect theoretical models for erosion to measurable properties in glaciers, we used computational landscape evolution experiments to study the expected influence of basal-ice debris concentration for subglacial abrasion at the scale of glaciers. The computational experiments couple the two erosion processes of quarrying and abrasion, and furthermore integrate the flow of ice and transport of debris within the ice, thus allowing for the study of dynamic feedbacks between subglacial erosion and systematic glacier-scale variations in basal-ice debris concentration. The experiments explored several physics-based models for glacial erosion, in combination with different models for basal sliding to elucidate the relationship between sliding speed, erosion rate and basal-ice debris concentration. The results demonstrate how differences in debris concentration can explain large variations in measured rates. The experiments also provide a simple explanation for the observed dependence of glacier-averaged rate of erosion on glacier size: that large glacier uplands feed more debris into their lower-elevation parts, thereby strengthening their erosive power.

  4. An integrated study to evaluate debris flow hazard in alpine environment

    Science.gov (United States)

    Tiranti, Davide; Crema, Stefano; Cavalli, Marco; Deangeli, Chiara

    2018-05-01

    Debris flows are among the most dangerous natural processes affecting the alpine environment due to their magnitude (volume of transported material) and the long runout. The presence of structures and infrastructures on alluvial fans can lead to severe problems in terms of interactions between debris flows and human activities. Risk mitigation in these areas requires identifying the magnitude, triggers, and propagation of debris flows. Here, we propose an integrated methodology to characterize these phenomena. The methodology consists of three complementary procedures. Firstly, we adopt a classification method based on the propensity of the catchment bedrocks to produce clayey-grained material. The classification allows us to identify the most likely rheology of the process. Secondly, we calculate a sediment connectivity index to estimate the topographic control on the possible coupling between the sediment source areas and the catchment channel network. This step allows for the assessment of the debris supply, which is most likely available for the channelized processes. Finally, with the data obtained in the previous steps, we modelled the propagation and depositional pattern of debris flows with a 3D code based on Cellular Automata. The results of the numerical runs allow us to identify the depositional patterns and the areas potentially involved in the flow processes. This integrated methodology is applied to a test-bed catchment located in Northwestern Alps. The results indicate that this approach can be regarded as a useful tool to estimate debris flow related potential hazard scenarios in an alpine environment in an expeditious way without possessing an exhaustive knowledge of the investigated catchment, including data on historical debris flow events.

  5. An Integrated Study to Evaluate Debris Flow Hazard in Alpine Environment

    Directory of Open Access Journals (Sweden)

    Davide Tiranti

    2018-05-01

    Full Text Available Debris flows are among the most dangerous natural processes affecting the alpine environment due to their magnitude (volume of transported material and the long runout. The presence of structures and infrastructures on alluvial fans can lead to severe problems in terms of interactions between debris flows and human activities. Risk mitigation in these areas requires identifying the magnitude, triggers, and propagation of debris flows. Here, we propose an integrated methodology to characterize these phenomena. The methodology consists of three complementary procedures. Firstly, we adopt a classification method based on the propensity of the catchment bedrocks to produce clayey-grained material. The classification allows us to identify the most likely rheology of the process. Secondly, we calculate a sediment connectivity index to estimate the topographic control on the possible coupling between the sediment source areas and the catchment channel network. This step allows for the assessment of the debris supply, which is most likely available for the channelized processes. Finally, with the data obtained in the previous steps, we modeled the propagation and depositional pattern of debris flows with a 3D code based on Cellular Automata. The results of the numerical runs allow us to identify the depositional patterns and the areas potentially involved in the flow processes. This integrated methodology is applied to a test-bed catchment located in Northwestern Alps. The results indicate that this approach can be regarded as a useful tool to estimate debris flow related potential hazard scenarios in an alpine environment in an expeditious way without possessing an exhaustive knowledge of the investigated catchment, including data on historical debris flow events.

  6. Integral analysis of debris material and heat transport in reactor vessel lower plenum

    International Nuclear Information System (INIS)

    Suh, K.Y.; Henry, R.E.

    1994-01-01

    An integral, fast-running, two-region model has been developed to characterize the debris material and heat transport in the reactor lower plenum under severe accident conditions. The debris bed is segregated into the oxidic pool and an overlying metallic layer. Debris crusts can develop on three surfaces: the top of the molten pool, the RPV wall, and the internal structures. To account for the decay heat generation, the crust temperature profile is assumed to be parabolic. The oxidic debris pool is homogeneously mixed and has the same material composition, and hence the same thermophysical properties, as the crusts, while the metallic constituents are assumed to rise to the top of the debris pool. Steady-state relationships are used to describe the heat transfer rates, with the assessment of solid or liquid state, and the liquid superheat in the pool being based on the average debris temperature. Natural convection heat transfer from the molten debris pool to the upper, lower and embedded crusts is calculated based on the pool Rayleigh number with the conduction heat transfer from the crusts being determined by the crust temperature profile. The downward heat flux is transferred to the lowest part of the RPV lower head through a crust-to-RPV contact resistance. The sideward heat flux is transferred to the upper regions of the RPV lower head as well as to the internal structures. The upward heat flux goes to the metal layer, water, or available heat sink structures above. Quenching due to water ingression is modeled separately from the energy transfer through the crust. The RPV wall temperature distribution and the primary system pressure are utilized to estimate challenges to the RPV integrity. ((orig.))

  7. Numerical investigation of debris materials prior to debris flow hazards using satellite images

    Science.gov (United States)

    Zhang, N.; Matsushima, T.

    2018-05-01

    The volume of debris flows occurred in mountainous areas is mainly affected by the volume of debris materials deposited at the valley bottom. Quantitative evaluation of debris materials prior to debris flow hazards is important to predict and prevent hazards. At midnight on 7th August 2010, two catastrophic debris flows were triggered by the torrential rain from two valleys in the northern part of Zhouqu City, NW China, resulting in 1765 fatalities and huge economic losses. In the present study, a depth-integrated particle method is adopted to simulate the debris materials, based on 2.5 m resolution satellite images. In the simulation scheme, the materials are modeled as dry granular solids, and they travel down from the slopes and are deposited at the valley bottom. The spatial distributions of the debris materials are investigated in terms of location, volume and thickness. Simulation results show good agreement with post-disaster satellite images and field observation data. Additionally, the effect of the spatial distributions of the debris materials on subsequent debris flows is also evaluated. It is found that the spatial distributions of the debris materials strongly influence affected area, runout distance and flow discharge. This study might be useful in hazard assessments prior to debris flow hazards by investigating diverse scenarios in which the debris materials are unknown.

  8. Fluid-bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, G.; Schoebotham, N.

    1981-02-01

    In Energy Equipment Company's two-stage fluidized bed system, partial combustion in a fluidized bed is followed by burn-off of the generated gases above the bed. The system can be retrofitted to existing boilers, and can burn small, high ash coal efficiently. It has advantages when used as a hot gas generator for process drying. Tests on a boiler at a Cadbury Schweppes plant are reported.

  9. Debris Disk Studies with the ngVLA

    Science.gov (United States)

    Wilner, David; Matthews, Brenda; Matra, Luca; Kennedy, Grant; Wyatt, Mark; Greaves, Jane

    2018-01-01

    We discuss the potential for the ngVLA to advance understanding of debris disks around main-sequence stars. Since the dust-producing planetesimals that replenish these disks through collisions persist only in stable regions like belts and resonances, their locations and physical properties encode essential information about the formation of exoplanetary systems and their dynamical evolution. Observations at long millimeter wavelengths can play a special role because the large grains that dominate the emission are faithful tracers of the dust-producing planetesimals, unlike small grains seen at shorter wavelengths that are rapidly redistributed by stellar radiation and winds. Sensitive observations of debris disks with the ngVLA can (1) reveal structures resulting from otherwise inaccessible planets on wide orbits, (2) test collisional models using spectral slopes to constrain mm/cm grain size distributions, and (3) for select sources, probe the water content of exocomets using the 21 cm HI line.

  10. Porous debris behavior modeling of QUENCH-02, QUENCH-03 and QUENCH-09 experiments

    International Nuclear Information System (INIS)

    Kisselev, A.E.; Kobelev, G.V.; Strizhov, V.F.; Vasiliev, A.D.

    2006-01-01

    The heat-up, melting, relocation, hydrogen generation phenomena, relevant for high-temperature stages both in a reactor case and small-scale integral tests like QUENCH, are governed in particular by heat and mass transfer in porous debris and molten pools which are formed in the core region. Porous debris formation and behavior in QUENCH experiments (QUENCH-02, QUENCH-03, QUENCH-09) plays a considerable role and its adequate modeling is important for thermal analysis. In particular, the analysis of QUENCH experiments shows that the major hydrogen release takes place in debris and melt regions formed in the upper part of the fuel assembly. The porous debris model was implemented in the Russian best estimate numerical code RATEG/SVECHA/HEFEST developed for modelling thermal hydraulics and severe accident phenomena in a reactor. The original approach for debris evolution is developed in the model from classical principles using a set of parameters including debris porosity; average particle diameter; temperatures and mass fractions of solid, liquid and gas phases; specific interface areas between different phases; effective thermal conductivity of each phase, including radiative heat conductivity; mass and energy fluxes through the interfaces. The debris model is based on the system of continuity, momentum and energy conservation equations, which consider the dynamics of volume-averaged velocities and temperatures of fluid, solid and gaseous phases of porous debris. The model is used for calculation of QUENCH experiments. The results obtained by the model are compared to experimental data concerning different aspects of thermal behavior: thermal hydraulics of porous debris, radiative heat transfer in a porous medium, the generalized melting and refreezing behavior of materials, hydrogen production. (author)

  11. Fluidised bed combustion system

    International Nuclear Information System (INIS)

    McKenzie, E.C.

    1976-01-01

    Fluidized bed combustion systems that facilitates the maintenance of the depth of the bed are described. A discharge pipe projects upwardly into the bed so that bed material can flow into its upper end and escape downwardly. The end of the pipe is surrounded by an enclosure and air is discharged into the enclosure so that material will enter the pipe from within the enclosure and have been cooled in the enclosure by the air discharged into it. The walls of the enclosure may themselves be cooled

  12. An experimental study on quenching of a radially stratified heated porous bed

    International Nuclear Information System (INIS)

    Nayak, Arun K.; Sehgal, Bal Raj; Stepanyan, Armen V.

    2006-01-01

    The quenching characteristics of a volumetrically-heated particulate bed composed of radially stratified sand layers were investigated experimentally in the POMECO facility. The sand bed simulates the corium particulate debris bed which is formed when the molten corium released from the vessel fragments in water and deposits on the cavity floor during a postulated severe accident in a light water reactor (LWR). The electrically-heated bed was quenched by water from a water column established over top of it, and later also with water coming from its bottom, which was circulating from the water overlayer through downcomers. A series of experiments were conducted to reveal the effects of the size of downcomers, and their locations in the bed, on the quenching characteristics of the radially stratified debris beds. The downcomers were found to significantly increase the bed quenching rate. To simulate the non-condensable gases generated during the MCCI, air and argon were injected from the bottom of the bed at different flow rates. The effects of gas flow rate and its properties on the quenching behaviour were observed. The results indicate that the non-condensable gas flows reduce the quenching rate significantly. The gas properties also affect the quenching characteristics

  13. Sampling supraglacial debris thickness using terrestrial photogrammetry

    Science.gov (United States)

    Nicholson, Lindsey; Mertes, Jordan

    2017-04-01

    The melt rate of debris-covered ice differs to that of clean ice primarily as a function of debris thickness. The spatial distribution of supraglacial debris thickness must therefore be known in order to understand how it is likely to impact glacier behaviour, and meltwater contribution to local hydrological resources and global sea level rise. However, practical means of determining debris cover thickness remain elusive. In this study we explore the utility of terrestrial photogrammetry to produce high resolution, scaled and texturized digital terrain models of debris cover exposures above ice cliffs as a means of quantifying and characterizing debris thickness. Two Nikon D5000 DSLRs with Tamron 100mm lenses were used to photograph a sample area of the Ngozumpa glacier in the Khumbu Himal of Nepal in April 2016. A Structure from Motion workflow using Agisoft Photoscan software was used to generate a surface models with <10cm resolution. A Trimble Geo7X differential GPS with Zephyr antenna, along with a local base station, was used to precisely measure marked ground control points to scale the photogrammetric surface model. Measurements of debris thickness along the exposed cliffline were made from this scaled model, assuming that the ice surface at the debris-ice boundary is horizontal, and these data are compared to 50 manual point measurements along the same clifftops. We conclude that sufficiently high resolution photogrammetry, with precise scaling information, provides a useful means to determine debris thickness at clifftop exposures. The resolution of the possible measurements depends on image resolution, the accuracy of the ground control points and the computational capacity to generate centimetre scale surface models. Application of such techniques to sufficiently high resolution imagery from UAV-borne cameras may offer a powerful means of determining debris thickness distribution patterns over debris covered glacier termini.

  14. The Fabulous Four Debris Disks

    Science.gov (United States)

    Werner, Michael; Stapelfeldt, Karl

    2004-09-01

    This program is a comprehensive study of the four bright debris disks that were spatially resolved by IRAS: Beta Pictoris, Epsilon Eridani, Fomalhaut, and Vega. All SIRTF instruments and observing modes will be used. The program has three major objectives: (1) Study of the disk spatial structure from MIPS and IRAC imaging; (2) Study of the dust grain composition using the IRS and MIPS SED mode; and (3) companion searches using IRAC. The data from this program should lead to a detailed understanding of these four systems, and will provide a foundation for understanding all of the debris disks to be studied with SIRTF. Images and spectra will be compared with models for disk structure and dust properties. Dynamical features indicative of substellar companions' effects on the disks will be searched for. This program will require supporting observations of PSF stars, some of which have been included explicitly. In the majority of cases, the spectral observations require a preferred orientation to align the slits along the disk position angles. Detector saturation issues are still being worked for this program, and will lead to AOR modifications in subsequent submissions. The results from this program will be analyzed collaboratively by the IRAC, IRS, and MIPS teams and by general GTOs Jura and Werner.

  15. Permeability and compression of fibrous porous media generated from dilute suspensions of fiberglass debris during a loss of coolant accident

    International Nuclear Information System (INIS)

    Lee, Saya; Abdulsattar, Suhaeb S.; Vaghetto, Rodolfo; Hassan, Yassin A.

    2015-01-01

    Highlights: • Experimental investigation on fibrous debris buildup was conducted. • Head loss through fibrous media was recorded at different approach velocities. • A head loss model through fibrous media was proposed for high porosity (>0.99). • A compression model of fibrous media was developed. - Abstract: Permeability of fibrous porous media has been studied for decades in various engineering applications, including liquid purifications, air filters, and textiles. In nuclear engineering, fiberglass has been found to be a hazard during a Loss-of-Coolant Accident. The high energy steam jet from a break impinges on surrounding fiberglass insulation materials, producing a large amount of fibrous debris. The fibrous debris is then transported through the reactor containment and reaches the sump strainers. Accumulation of such debris on the surface of the strainers produces a fibrous bed, which is a fibrous porous medium that can undermine reactor core cooling. The present study investigated the buildup of fibrous porous media on two types of perforated plate and the pressure drop through the fibrous porous media without chemical effect. The development of the fibrous bed was visually recorded in order to correlate the pressure drop, the approach velocity, and the thickness of the fibrous porous media. The experimental results were compared to semi-theoretical models and theoretical models proposed by other researchers. Additionally, a compression model was developed to predict the thickness and the local porosity of a fibrous bed as a function of pressure

  16. Sediment concentration and bed form structures of Gulf of Cambay from remote sensing

    Digital Repository Service at National Institute of Oceanography (India)

    Kunte, P.D.

    period, the bottom currents pull sediment (sand) particles supplied by major and minor rivers, rolling along the Gulf bed. These sediments perhaps participate in the formation of bed form structures. The topography of the Gulf bottom comprises of numerous...

  17. Field measurement of basal forces generated by erosive debris flows

    Science.gov (United States)

    McCoy, S.W.; Tucker, G.E.; Kean, J.W.; Coe, J.A.

    2013-01-01

    It has been proposed that debris flows cut bedrock valleys in steeplands worldwide, but field measurements needed to constrain mechanistic models of this process remain sparse due to the difficulty of instrumenting natural flows. Here we present and analyze measurements made using an automated sensor network, erosion bolts, and a 15.24 cm by 15.24 cm force plate installed in the bedrock channel floor of a steep catchment. These measurements allow us to quantify the distribution of basal forces from natural debris‒flow events that incised bedrock. Over the 4 year monitoring period, 11 debris‒flow events scoured the bedrock channel floor. No clear water flows were observed. Measurements of erosion bolts at the beginning and end of the study indicated that the bedrock channel floor was lowered by 36 to 64 mm. The basal force during these erosive debris‒flow events had a large‒magnitude (up to 21 kN, which was approximately 50 times larger than the concurrent time‒averaged mean force), high‒frequency (greater than 1 Hz) fluctuating component. We interpret these fluctuations as flow particles impacting the bed. The resulting variability in force magnitude increased linearly with the time‒averaged mean basal force. Probability density functions of basal normal forces were consistent with a generalized Pareto distribution, rather than the exponential distribution that is commonly found in experimental and simulated monodispersed granular flows and which has a lower probability of large forces. When the bed sediment thickness covering the force plate was greater than ~ 20 times the median bed sediment grain size, no significant fluctuations about the time‒averaged mean force were measured, indicating that a thin layer of sediment (~ 5 cm in the monitored cases) can effectively shield the subjacent bed from erosive impacts. Coarse‒grained granular surges and water‒rich, intersurge flow had very similar basal force distributions despite

  18. Hydrodynamics of circulating and bubbling fluidized beds

    International Nuclear Information System (INIS)

    Gidaspow, D.P.; Tsuo, Y.P.; Ding, J.

    1991-01-01

    This paper reports that a review of modeling of the hydrodynamics of fluidization of bubbling beds showed that inviscid two-fluid models were able to predict a great deal of the behavior of bubbling beds because the dominant mechanism of energy dissipation is the drag between the particles and the fluid. The formation, the growth and the bursting of bubbles were predicted. Predicted wall-to-bed heat transfer coefficients and velocity profiles of jets agreed with measurements. Time average porosity distributions agreed with measurements done using gamma-ray densitometers without the use of any adjustable parameters. However, inviscid models could not correctly predict rates of erosion around tubes immersed into fluidized beds. To correctly model such behavior, granular stresses involving solids viscosity were added into the computer model. This viscosity arises due to random collision of particles. Several models fro this viscosity were investigated and the results compared to measurements of solids distributions in two-dimensional beds and to particle velocities reported in the literature. While in the case of bubbling beds the solids viscosity plays the role of a correction, modeling of a circulating fluidized bed (CFB) without a viscosity is not possible. Recent experimental data obtained at IIT and at IGT show that in CFB the solids viscous dissipation is responsible for as much as half of the pressure drop. From such measurement, solids viscosities were computed. These were used in the two fluid hydrodynamic model, to predict radial solids distributions and solids velocities which matched the experimental distributions. Most important, the model predicted cluster formation and transient internal circulation which is responsible for the favorable characteristics of CFBs, such as good wall-to-bed heat transfer. Video tape movies of computations compared favorably with high speed movies of the experiments

  19. Fluidized bed incinerator development

    International Nuclear Information System (INIS)

    Ziegler, D.L.; Johnson, A.J.

    1976-01-01

    A fluidized bed incinerator is being developed for burning rad contaminated solid and liquid waste materials. In situ neutralization of acid gases by the bed material, catalytic afterburning, and gas filtration are used to produce a clean flue gas without the use of aqueous scrubbing

  20. Debris flows: behavior and hazard assessment

    Science.gov (United States)

    Iverson, Richard M.

    2014-01-01

    Debris flows are water-laden masses of soil and fragmented rock that rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form lobate deposits when they spill onto valley floors. Because they have volumetric sediment concentrations that exceed 40 percent, maximum speeds that surpass 10 m/s, and sizes that can range up to ~109 m3, debris flows can denude slopes, bury floodplains, and devastate people and property. Computational models can accurately represent the physics of debris-flow initiation, motion and deposition by simulating evolution of flow mass and momentum while accounting for interactions of debris' solid and fluid constituents. The use of physically based models for hazard forecasting can be limited by imprecise knowledge of initial and boundary conditions and material properties, however. Therefore, empirical methods continue to play an important role in debris-flow hazard assessment.

  1. The flooding phenomenon and its connection with dry-out in boiling particle beds

    International Nuclear Information System (INIS)

    Macbeth, R.V.; Anderson, A.R.

    1986-03-01

    Experimental studies of boiling in particle beds representing reactor core debris have been restricted to very small beds compared with those that may be found in a reactor. The use of air and water to simulate some of the many features of boiling in a particle bed has given results that were inconclusive. The work reported here is that carried out at Winfrith to extend the dryout data to larger particle diameters, and to provide new experimental data which removes earlier doubts, and makes the air-water analogue position much clearer. (U.K.)

  2. Coupled Eulerian-Lagrangian transport of large debris by tsunamis

    Science.gov (United States)

    Conde, Daniel A. S.; Ferreira, Rui M. L.; Sousa Oliveira, Carlos

    2016-04-01

    conservativeness of the model. This way, in highly resolved meshes and high quantities of debris, the model approaches full conservativeness only if the two-way coupling feature is present, an effect that is attenuated in coarse meshes or with small debris quantities. Aknownledgements: This work was partially funded by FEDER, program COMPETE, and by national funds through the Portuguese Foundation for Science and Technology (FCT) with project RECI/ECM-HID/0371/2012. References: Baptista M.A. & Miranda, J.M. (2009) Revision of the Portuguese catalog of tsunamis. Nat. Hazards Earth Syst. Sci., 9, 25-42. Conde, D. A. S.; Baptista, M. A. V.; Sousa Oliveira, C. & Ferreira, R. M. L. (2013) A shallow-flow model for the propagation of tsunamis over complex geometries and mobile beds, Nat. Hazards Earth Syst. Sci., 13, 2533-2542. Conde, D. A. S.; Baptista, M. A. V.; Sousa Oliveira, C. & Ferreira, R. M. L. (2015) Mathematical modelling of tsunami impacts on critical infrastructures: exposure and severity associated with debris transport at Sines port. EGU General Assembly 2015, Vienna, Austria. Ferreira, R. M. L.; Franca, M. J.; Leal, J. G. & Cardoso, A. H. (2009) Mathematical modelling of shallow flows: Closure models drawn from grain-scale mechanics of sediment transport and flow hydrodynamics, Can. J. Civil. Eng., 36, 1604-1621. LeVeque, R. J., George, D. L., & Berger, M. J. (2011) Tsunami modelling with adaptively refined finite volume methods, Acta Numerica, pp. 211-289.

  3. What Sets the Radial Locations of Warm Debris Disks?

    Energy Technology Data Exchange (ETDEWEB)

    Ballering, Nicholas P.; Rieke, George H.; Su, Kate Y. L.; Gáspár, András, E-mail: ballerin@email.arizona.edu [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2017-08-20

    The architectures of debris disks encode the history of planet formation in these systems. Studies of debris disks via their spectral energy distributions (SEDs) have found infrared excesses arising from cold dust, warm dust, or a combination of the two. The cold outer belts of many systems have been imaged, facilitating their study in great detail. Far less is known about the warm components, including the origin of the dust. The regularity of the disk temperatures indicates an underlying structure that may be linked to the water snow line. If the dust is generated from collisions in an exo-asteroid belt, the dust will likely trace the location of the water snow line in the primordial protoplanetary disk where planetesimal growth was enhanced. If instead the warm dust arises from the inward transport from a reservoir of icy material farther out in the system, the dust location is expected to be set by the current snow line. We analyze the SEDs of a large sample of debris disks with warm components. We find that warm components in single-component systems (those without detectable cold components) follow the primordial snow line rather than the current snow line, so they likely arise from exo-asteroid belts. While the locations of many warm components in two-component systems are also consistent with the primordial snow line, there is more diversity among these systems, suggesting additional effects play a role.

  4. Preliminary study of the favorability for uranium in the Madera Limestone, and Cutler and Chinle Formations of the Sierra Nacimiento-Jemez Mountains area, New Mexico

    International Nuclear Information System (INIS)

    Vizcaino, H.P.; O'Neill, A.J.; Dotterer, F.E.

    1978-01-01

    Small, surficial, secondary uranium deposits are present in several formations in the Sierra Nacimiento-Jemez Mountains region, but none of significant size are known. Field surveys indicate that the deposits are laterally discontinuous and are, in most cases, associated with carbonaceous debris. Mineral contents of as much as 0.18 percent U 3 O 8 are recorded. There are 2 known deposits in the Pennsylvanian Madera Limestone, 18 in the Permian Cutler Formation, and 3 in the Triassic Chinle Formation. The Madera Limestone consists of a lower and an upper member. The lower member is predominantly a dense limestone and is lithologically unfavorable. The upper member, which consists of several arkosic units interbedded with cherty limestone, is not a favorable host rock because of its thin arkosic units, the paucity of carbonaceous debris, and its lithologically unfavorable limestone. The Cutler Formation consists mostly of interfingering siltstones and fine- to coarse-grained feldspathic and arkosic sandstones of fluvial origin. The sandstones are generally lenticular, average about 40 ft in thickness, and are favorable. Cutler equivalents south of lat 36 0 N. (Abo and Yeso Formations) were not included in this study. The Chinle Formation in the project area consists of five members. The Agua Zarca Member, medium-grained to conglomeratic sandstone with beds that average 30 ft in thickness, is the only unit in the Chinle considered favorable. The stratigraphic units under consideration have been eroded and deformed; beds dip steeply. Upturned and deeply dissected beds afford access to infiltrating waters; oxidation and flushing of pre-existing uranium deposits is therefore suspected. The uranium deposits in the Madera, Cutler, and Chinle are likely to be remnants, and the probability of locating any large deposits within the area is therefore low

  5. An experimental study on coolability of a particulate bed with radial stratification or triangular shape

    International Nuclear Information System (INIS)

    Thakre, Sachin; Li, Liangxing; Ma, Weimin

    2014-01-01

    Highlights: • Dryout heat flux of a particulate bed with radial stratification is obtained. • It was found to be dominated by hydrodynamics in the bigger size of particle layer. • Coolability of a particulate bed with triangular shape is investigated. • The coolability is improved in the triangular bed due to lateral ingression of coolant. • Coolability of both beds is enhanced by a downcomer. - Abstract: This paper deals with the results of an experimental study on the coolability of particulate beds with radial stratification and triangular shape, respectively. The study is intended to get an idea on how the coolability is affected by the different features of a debris bed formed in a severe accident of light water reactors. The experiments were performed on the POMECO-HT facility which was constructed to investigate two-phase flow and heat transfer in particulate beds under either top-flooding or bottom-fed condition. A downcomer is designed to enable investigation of the effectiveness of natural circulation driven coolability. Two homogenous beds were also employed in the present study to compare their dryout power densities with those of the radially stratified bed and the triangular bed. The results show that the dryout heat fluxes of the homogeneous beds at top-flooding condition can be predicted by the Reed model. For the radially stratified bed, the dryout heat flux is dominated by two-phase flow in the columns packed with larger particles, and the dryout occurred initially near the boundary between the middle column and a side column. Given the same volume of particles under top-flooding condition, the dryout power density of the triangular bed is about 69% higher than that of the homogenous bed. The coolability of all the beds is enhanced by bottom-fed coolant driven by either forced injection or downcomer-induced natural circulation

  6. An experimental study on coolability of a particulate bed with radial stratification or triangular shape

    Energy Technology Data Exchange (ETDEWEB)

    Thakre, Sachin; Li, Liangxing; Ma, Weimin, E-mail: ma@safety.sci.kth.se

    2014-09-15

    Highlights: • Dryout heat flux of a particulate bed with radial stratification is obtained. • It was found to be dominated by hydrodynamics in the bigger size of particle layer. • Coolability of a particulate bed with triangular shape is investigated. • The coolability is improved in the triangular bed due to lateral ingression of coolant. • Coolability of both beds is enhanced by a downcomer. - Abstract: This paper deals with the results of an experimental study on the coolability of particulate beds with radial stratification and triangular shape, respectively. The study is intended to get an idea on how the coolability is affected by the different features of a debris bed formed in a severe accident of light water reactors. The experiments were performed on the POMECO-HT facility which was constructed to investigate two-phase flow and heat transfer in particulate beds under either top-flooding or bottom-fed condition. A downcomer is designed to enable investigation of the effectiveness of natural circulation driven coolability. Two homogenous beds were also employed in the present study to compare their dryout power densities with those of the radially stratified bed and the triangular bed. The results show that the dryout heat fluxes of the homogeneous beds at top-flooding condition can be predicted by the Reed model. For the radially stratified bed, the dryout heat flux is dominated by two-phase flow in the columns packed with larger particles, and the dryout occurred initially near the boundary between the middle column and a side column. Given the same volume of particles under top-flooding condition, the dryout power density of the triangular bed is about 69% higher than that of the homogenous bed. The coolability of all the beds is enhanced by bottom-fed coolant driven by either forced injection or downcomer-induced natural circulation.

  7. Space Debris Removal: A Game Theoretic Analysis

    Directory of Open Access Journals (Sweden)

    Richard Klima

    2016-08-01

    Full Text Available We analyse active space debris removal efforts from a strategic, game-theoretical perspective. Space debris is non-manoeuvrable, human-made objects orbiting Earth, which pose a significant threat to operational spacecraft. Active debris removal missions have been considered and investigated by different space agencies with the goal to protect valuable assets present in strategic orbital environments. An active debris removal mission is costly, but has a positive effect for all satellites in the same orbital band. This leads to a dilemma: each agency is faced with the choice between the individually costly action of debris removal, which has a positive impact on all players; or wait and hope that others jump in and do the ‘dirty’ work. The risk of the latter action is that, if everyone waits, the joint outcome will be catastrophic, leading to what in game theory is referred to as the ‘tragedy of the commons’. We introduce and thoroughly analyse this dilemma using empirical game theory and a space debris simulator. We consider two- and three-player settings, investigate the strategic properties and equilibria of the game and find that the cost/benefit ratio of debris removal strongly affects the game dynamics.

  8. Analysis of the Herschel DEBRIS Sun-like star sample

    Science.gov (United States)

    Sibthorpe, B.; Kennedy, G. M.; Wyatt, M. C.; Lestrade, J.-F.; Greaves, J. S.; Matthews, B. C.; Duchêne, G.

    2018-04-01

    This paper presents a study of circumstellar debris around Sun-like stars using data from the Herschel DEBRIS Key Programme. DEBRIS is an unbiased survey comprising the nearest ˜90 stars of each spectral type A-M. Analysis of the 275 F-K stars shows that excess emission from a debris disc was detected around 47 stars, giving a detection rate of 17.1^{+2.6}_{-2.3} per cent, with lower rates for later spectral types. For each target a blackbody spectrum was fitted to the dust emission to determine its fractional luminosity and temperature. The derived underlying distribution of fractional luminosity versus blackbody radius in the population showed that most detected discs are concentrated at f ˜ 10-5 and at temperatures corresponding to blackbody radii 7-40 au, which scales to ˜40 au for realistic dust properties (similar to the current Kuiper belt). Two outlying populations are also evident; five stars have exceptionally bright emission ( f > 5 × 10-5), and one has unusually hot dust <4 au. The excess emission distributions at all wavelengths were fitted with a steady-state evolution model, showing that these are compatible with all stars being born with a narrow belt that then undergoes collisional grinding. However, the model cannot explain the hot dust systems - likely originating in transient events - and bright emission systems - arising potentially from atypically massive discs or recent stirring. The emission from the present-day Kuiper belt is predicted to be close to the median of the population, suggesting that half of stars have either depleted their Kuiper belts (similar to the Solar system) or had a lower planetesimal formation efficiency.

  9. LATE PLIOCENE-HOLOCENE DEBRIS FLOW DEPOSITS IN THE IONIAN SEA (EASTERN MEDITERRANEAN

    Directory of Open Access Journals (Sweden)

    GIOVANNI ALOISI DE LARDEREL

    1997-11-01

    Full Text Available Widespread coring of the Eastern Mediterranean Basin has outlined the existence of a systematic relation between lithology of debris flow deposits and physiographic setting. Whilst the topographic highs are characterized by pelagic sedimentation, the basin floors are alternatively subject to pelagic sedimentation and re-sedimentation pro cesses. Amongst the latters, turbidity flows and debris flows are the most common transport mechanisms.In this paper we present the study of the debris flow pro cess in the Ionian Sea using visual description of cores, grain size, carbonate content and smear slide analysis carried out on gravity and piston cores recovered over the past 20 years. A distinction has been made between debris flow deposits originating from the continental margins (North Africa and Malta Escarpment and those emplaced in the small basins amidst the Calabrian and Mediterranean ridges "Cobblestone Topography". As a result of the difference in setting, the former debris flow deposits include a great variety of lithologies and ages whilst the latter involve the pelagic sediments forming the typical Eastern Mediterranean Plio-Quaternary succession. A detailed study of clast and matrix structures makes it possible to describe the flows in terms of existing classifications of sediment gravity flows and to assume a clast support mechanism. Finally, biostratigraphy coupled with the presence of widespread marker beds enabled us to estimate the age of emplacement of the deposits and to hypothesize a triggering mechanism for flow initiation. Three flows are strictly related to the pelagic turbidite named homogenite, triggered by the explosive eruption of the Santorini volcano (Minoan eruption and therefore have an estimated age of 3,500 BP. The other deposits have ages ranging from 9,000 BP to about 70,000 BP and were originated by debris flows triggered by events such as earthquakes and glacial low sea level stands.    

  10. Scaling up debris-flow experiments on a centrifuge

    Science.gov (United States)

    Hung, C.; Capart, H.; Crone, T. J.; Grinspum, E.; Hsu, L.; Kaufman, D.; Li, L.; Ling, H.; Reitz, M. D.; Smith, B.; Stark, C. P.

    2013-12-01

    Boundary forces generated by debris flows can be powerful enough to erode bedrock and cause considerable damage to infrastructure during runout. Formulation of an erosion-rate law for debris flows is therefore a high priority, and it makes sense to build such a law around laboratory experiments. However, running experiments big enough to generate realistic boundary forces is a logistical challenge to say the least [1]. One alternative is to run table-top simulations with unnaturally weak but fast-eroding pseudo-bedrock, another is to extrapolate from micro-erosion of natural substrates driven by unnaturally weak impacts; hybrid-scale experiments have also been conducted [2]. Here we take a different approach in which we scale up granular impact forces by running our experiments under enhanced gravity in a geotechnical centrifuge [3]. Using a 40cm-diameter rotating drum [2] spun at up to 100g, we generate debris flows with an effective depth of over several meters. By varying effective gravity from 1g to 100g we explore the scaling of granular flow forces and the consequent bed and wall erosion rates. The velocity and density structure of these granular flows is monitored using laser sheets, high-speed video, and particle tracking [4], and the progressive erosion of the boundary surfaces is measured by laser scanning. The force structures and their fluctuations within the granular mass and at the boundaries are explored with contact dynamics numerical simulations that mimic the lab experimental conditions [5]. In this presentation we summarize these results and discuss how they can contribute to the formulation of debris-flow erosion law. [1] Major, J. J. (1997), Journal of Geology 105: 345-366, doi:10.1086/515930 [2] Hsu, L. (2010), Ph.D. thesis, University of California, Berkeley [3] Brucks, A., et al (2007), Physical Review E 75, 032301, doi:10.1103/PhysRevE.75.032301 [4] Spinewine, B., et al (2011), Experiments in Fluids 50: 1507-1525, doi: 10.1007/s00348

  11. Orbital Debris and NASA's Measurement Program

    Science.gov (United States)

    Africano, J. L.; Stansbery, E. G.

    2002-05-01

    Since the launch of Sputnik in 1957, the number of manmade objects in orbit around the Earth has dramatically increased. The United States Space Surveillance Network (SSN) tracks and maintains orbits on over nine thousand objects down to a limiting diameter of about ten centimeters. Unfortunately, active spacecraft are only a small percentage ( ~ 7%) of this population. The rest of the population is orbital debris or ``space junk" consisting of expended rocket bodies, dead payloads, bits and pieces from satellite launches, and fragments from satellite breakups. The number of these smaller orbital debris objects increases rapidly with decreasing size. It is estimated that there are at least 130,000 orbital debris objects between one and ten centimeters in diameter. Most objects smaller than 10 centimeters go untracked! As the orbital debris population grows, the risk to other orbiting objects, most importantly manned space vehicles, of a collision with a piece of debris also grows. The kinetic energy of a solid 1 cm aluminum sphere traveling at an orbital velocity of 10 km/sec is equivalent to a 400 lb. safe traveling at 60 mph. Fortunately, the volume of space in which the orbiting population resides is large, collisions are infrequent, but they do occur. The Space Shuttle often returns to earth with its windshield pocked with small pits or craters caused by collisions with very small, sub-millimeter-size pieces of debris (paint flakes, particles from solid rocket exhaust, etc.), and micrometeoroids. To get a more complete picture of the orbital-debris environment, NASA has been using both radar and optical techniques to monitor the orbital debris environment. This paper gives an overview of the orbital debris environment and NASA's measurement program.

  12. POST Earthquake Debris Management — AN Overview

    Science.gov (United States)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  13. POST Earthquake Debris Management - AN Overview

    Science.gov (United States)

    Sarkar, Raju

    Every year natural disasters, such as fires, floods, earthquakes, hurricanes, landslides, tsunami, and tornadoes, challenge various communities of the world. Earthquakes strike with varying degrees of severity and pose both short- and long-term challenges to public service providers. Earthquakes generate shock waves and displace the ground along fault lines. These seismic forces can bring down buildings and bridges in a localized area and damage buildings and other structures in a far wider area. Secondary damage from fires, explosions, and localized flooding from broken water pipes can increase the amount of debris. Earthquake debris includes building materials, personal property, and sediment from landslides. The management of this debris, as well as the waste generated during the reconstruction works, can place significant challenges on the national and local capacities. Debris removal is a major component of every post earthquake recovery operation. Much of the debris generated from earthquake is not hazardous. Soil, building material, and green waste, such as trees and shrubs, make up most of the volume of earthquake debris. These wastes not only create significant health problems and a very unpleasant living environment if not disposed of safely and appropriately, but also can subsequently impose economical burdens on the reconstruction phase. In practice, most of the debris may be either disposed of at landfill sites, reused as materials for construction or recycled into useful commodities Therefore, the debris clearance operation should focus on the geotechnical engineering approach as an important post earthquake issue to control the quality of the incoming flow of potential soil materials. In this paper, the importance of an emergency management perspective in this geotechnical approach that takes into account the different criteria related to the operation execution is proposed by highlighting the key issues concerning the handling of the construction

  14. Design of full scale debris washing system

    International Nuclear Information System (INIS)

    Taylor, M.L.; Dosani, M.A.; Wentz, J.A.; Patkar, A.N.; Barkley, N.P.

    1992-01-01

    Since 1987, IT Environmental Programs Inc. (ITEP, a subsidiary of International Technology Corporation) in conjunction with EPA/RREL in Cincinnati, Ohio, have been developing and conducting bench scale and pilot scale testing of a transportable debris washing system which can be used on-site for the decontamination of debris. During the initial phase of the debris decontamination project, a series of bench scale tests were performed in the laboratory to assess the ability of the system to remove contaminants from debris and to facilitate selection of the most efficient surfactant solution. Five nonionic, non-toxic, low foaming, surfactant solution (BG-5, MC-2000, LF-330, BB-100, and L-433) were selected for an experimental evaluation to determine their capacity to solubilize and remove contaminants from the surfaces of corroded steel places. The pieces of corroded steel were coated with a heavy grease mixture prepared in the laboratory and these pieces of debris were placed in a bench scale spray tank on a metal tray and subjected in a high-pressure spray for each surfactant solution for 15 minutes. At the end of the spray cycle, The tray was transferred to a second bench scale system, a high-turbulence wash tank, where the debris was washed for 30 minutes with the same surfactant solution as the used in the spray tank. After the was cycle was completed, the tray was removed from the wash tank and the debris was allowed to air-dry. Before and after treatment, surface-wipe samples were obtained from each of the six pieces of debris and were analyzed for oil and graese. Based on the results, BG-5 was selected as the solution best suited for cleaning grease-laden, metallic debris. 2 refs

  15. Temporal Dynamics of Bacterial and Fungal Colonization on Plastic Debris in the North Sea.

    Science.gov (United States)

    De Tender, Caroline; Devriese, Lisa I; Haegeman, Annelies; Maes, Sara; Vangeyte, Jürgen; Cattrijsse, André; Dawyndt, Peter; Ruttink, Tom

    2017-07-05

    Despite growing evidence that biofilm formation on plastic debris in the marine environment may be essential for its biodegradation, the underlying processes have yet to be fully understood. Thus, far, bacterial biofilm formation had only been studied after short-term exposure or on floating plastic, yet a prominent share of plastic litter accumulates on the seafloor. In this study, we explored the taxonomic composition of bacterial and fungal communities on polyethylene plastic sheets and dolly ropes during long-term exposure on the seafloor, both at a harbor and an offshore location in the Belgian part of the North Sea. We reconstructed the sequence of events during biofilm formation on plastic in the harbor environment and identified a core bacteriome and subsets of bacterial indicator species for early, intermediate, and late stages of biofilm formation. Additionally, by implementing ITS2 metabarcoding on plastic debris, we identified and characterized for the first time fungal genera on plastic debris. Surprisingly, none of the plastics exposed to offshore conditions displayed the typical signature of a late stage biofilm, suggesting that biofilm formation is severely hampered in the natural environment where most plastic debris accumulates.

  16. Fluidized bed volume reduction of diverse radwastes

    International Nuclear Information System (INIS)

    McFee, J.N.; McConnell, J.W.; Waddoups, D.A.; Gray, M.F.; Harwood, L.E.; Clayton, N.J.; Drown, D.C.

    1981-01-01

    Method and apparatus for a fluidized bed radwaste volume reduction system are claimed. Low level radioactive wastes, combustible solids, ion exchange resins and filter sludges, and liquids, emanating from a reactor facility are introduced separately through an integrated waste influent system into a common fluidized bed vessel where volume reduction either through incineration or calcination occurs. Addition of a substance to the ion exchange resin before incineration inhibits the formation of low-melting point materials which tend to form clinkers in the bed. Solid particles are scrubbed or otherwise removed from the gaseous effluent of the vessel in an off-gas system, before the cooled and cleaned off-gas is released to the atmosphere. Iodine is chemically or physically removed from the off-gas. Otherwise, the only egress materials from the volume reduction system are containerized dry solids and tramp material. The bed material used during each mode may be circulated, cleaned, stored and exchanged from within the bed vessel by use of a bed material handling system. An instrumentation and control system provides operator information, monitors performance characteristics, implements start up and shut down procedures, and initiates alarms and emergency procedures during abnormal conditions

  17. Apparatus for controlling nuclear core debris

    International Nuclear Information System (INIS)

    Jones, R.D.

    1978-01-01

    Disclosed is an apparatus for containing, cooling, and dispersing reactor debris assumed to flow from the core area in the unlikely event of an accident causing core meltdown. The apparatus includes a plurality of horizontally disposed vertically spaced plates, having depressions to contain debris in controlled amounts, and a plurality of holes therein which provide natural circulation cooling and a path for debris to continue flowing downward to the plate beneath. The uppermost plates may also include generally vertical sections which form annular-like flow areas which assist the natural circulation cooling

  18. Apparatus for controlling nuclear core debris

    Science.gov (United States)

    Jones, Robert D.

    1978-01-01

    Nuclear reactor apparatus for containing, cooling, and dispersing reactor debris assumed to flow from the core area in the unlikely event of an accident causing core meltdown. The apparatus includes a plurality of horizontally disposed vertically spaced plates, having depressions to contain debris in controlled amounts, and a plurality of holes therein which provide natural circulation cooling and a path for debris to continue flowing downward to the plate beneath. The uppermost plates may also include generally vertical sections which form annular-like flow areas which assist the natural circulation cooling.

  19. Development of debris resistant bottom end piece

    International Nuclear Information System (INIS)

    Lee, Jae Kyung; Sohn, Dong Seong; Yim, Jeong Sik; Hwang, Dae Hyun; Song, Kee Nam; Oh, Dong Seok; Rhu, Ho Sik; Lee, Chang Woo; Kim, Seong Soo; Oh, Jong Myung

    1993-12-01

    Debris-related fuel failures have been identified as one of the major causes of fuel failures. In order to reduce the possibility of debris-related fuel failures, it is necessary to develop Debris-Resistant Bottom End Piece. For this development, mechanical strength test and pressure drop test were performed, and the test results were analyzed. And the laser cutting, laser welding and electron beam welding technology, which were the core manufacturing technology of DRBEP, were developed. Final design were performed, and the final drawing and specifications were prepared. The prototype of DRBEP was manufactured according to the developed munufacturing procedure. (Author)

  20. Algorithms for the Computation of Debris Risk

    Science.gov (United States)

    Matney, Mark J.

    2017-01-01

    Determining the risks from space debris involve a number of statistical calculations. These calculations inevitably involve assumptions about geometry - including the physical geometry of orbits and the geometry of satellites. A number of tools have been developed in NASA’s Orbital Debris Program Office to handle these calculations; many of which have never been published before. These include algorithms that are used in NASA’s Orbital Debris Engineering Model ORDEM 3.0, as well as other tools useful for computing orbital collision rates and ground casualty risks. This paper presents an introduction to these algorithms and the assumptions upon which they are based.

  1. Algorithms for the Computation of Debris Risks

    Science.gov (United States)

    Matney, Mark

    2017-01-01

    Determining the risks from space debris involve a number of statistical calculations. These calculations inevitably involve assumptions about geometry - including the physical geometry of orbits and the geometry of non-spherical satellites. A number of tools have been developed in NASA's Orbital Debris Program Office to handle these calculations; many of which have never been published before. These include algorithms that are used in NASA's Orbital Debris Engineering Model ORDEM 3.0, as well as other tools useful for computing orbital collision rates and ground casualty risks. This paper will present an introduction to these algorithms and the assumptions upon which they are based.

  2. Bed Bugs FAQs

    Science.gov (United States)

    ... Europe. Bed bugs have been found in five-star hotels and resorts and their presence is not ... Health – Division of Parasitic Diseases Email Recommend Tweet YouTube Instagram Listen Watch RSS ABOUT About CDC Jobs ...

  3. Bed Bug Information Clearinghouse

    Science.gov (United States)

    Its purpose is to help states, communities, and consumers in efforts to prevent and control bed bug infestations. Currently includes only reviewed material from federal/state/local government agencies, extension services, and universities.

  4. Particle fuel bed tests

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H 2 for 12 hours with no visible reaction or weight loss

  5. Development of debris-resistant bottom end piece

    International Nuclear Information System (INIS)

    Sohn, Dong Seong; Lee, Jae Kyung; Hwang, Dae Hyun; Yim, Jung Sik; Song, Kee Nam; Oh, Dong Seok; Im, Hyun Tae

    1993-01-01

    Debris-related fuel failures has been identified to be one of the major causes of fuel failures recently occured in nuclear power plants. In order to reduce the possibility of debris-related fuel failures, it is necessary to prevent the debris from reaching to fuel rods. In this regard, it is important to develop Debris-Resistant Bottom End Piece. (Author)

  6. Characterization of Porteresia coarctata beds along the Goa coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Jagtap, T.G.; Bhosale, S.H.; Charulata, S.

    Porteresia coarctata, forms an important constituent in the plant succession leading to formation of mangrove communities along the estuaries in India. Major beds along the Mandovi estuary of Goa were monitored for their various ecological...

  7. Debris Examination Using Ballistic and Radar Integrated Software

    Science.gov (United States)

    Griffith, Anthony; Schottel, Matthew; Lee, David; Scully, Robert; Hamilton, Joseph; Kent, Brian; Thomas, Christopher; Benson, Jonathan; Branch, Eric; Hardman, Paul; hide

    2012-01-01

    The Debris Examination Using Ballistic and Radar Integrated Software (DEBRIS) program was developed to provide rapid and accurate analysis of debris observed by the NASA Debris Radar (NDR). This software provides a greatly improved analysis capacity over earlier manual processes, allowing for up to four times as much data to be analyzed by one-quarter of the personnel required by earlier methods. There are two applications that comprise the DEBRIS system: the Automated Radar Debris Examination Tool (ARDENT) and the primary DEBRIS tool.

  8. Structural debris experiments at operation MILL RACE

    International Nuclear Information System (INIS)

    Rempel, J.R.; Beck, J.E.; McKee, R.G.

    1983-01-01

    Structural debris patterns as determined by the mechanisms of building collapse under airblast loading have been studied experimentally at MILL RACE, White Sands, NM. Three near full-size buildings were instrumented to observe deflections, accelerations and air pressures and exposed to two different regimes of incident blast pressure produced by HE simulating 1 kt, viz., 10 and 3 psi; after the shot enough wall debris was located and identified to provide estimates of debris movement. Two of the test buildings were unreinforced, load-bearing masonry, one located at each of the two incident overpressures. The third building was made of reinforced concrete panels and was exposed to approximately 25 psi. Preliminary estimates of the effect of arching on debris energy and distribution are presented

  9. New solutions for the space debris problem

    CERN Document Server

    Pelton, Joseph N

    2015-01-01

    Addressing a pressing issue in space policy, Pelton explores the new forms of technology that are being developed to actively remove the defunct space objects from orbit and analyzes their implications in the existing regime of international space law and public international law. This authoritative review covers the due diligence guidelines that nations are using to minimize the generation of new debris, mandates to de-orbit satellites at end of life, and innovative endeavours to remove non-functional satellites, upper stage rockets and other large debris from orbit under new institutional, financial and regulatory guidelines.  Commercial space services currently exceed 100 billion USD business per annum, but the alarming proliferation in the population of orbital debris in low, medium and geosynchronous satellite orbits poses a serious threat to all kinds of space assets and applications. There is a graver concern that the existing space debris will begin to collide in a cascading manner, generating furth...

  10. TMI defueling project fuel debris removal system

    International Nuclear Information System (INIS)

    Burdge, B.

    1992-01-01

    The three mile Island Unit 2 (TMI-2) pressurized water reactor loss-of-coolant accident on March 28, 1979, presented the nuclear community with many challenging remediation problems; most importantly, the removal of the fission products within the reactor containment vessel. To meet this removal problem, an air-lift system (ALS) can be used to employ compressed air to produce the motive force for transporting debris. Debris is separated from the transport stream by gravity separation. The entire method does not rely on any moving parts. Full-scale testing of the ALS at the Idaho National Engineering Laboratory (INEL) has demonstrated the capability of transporting fuel debris from beneath the LCSA into a standard fuel debris bucket at a minimum rate of 230 kg/min

  11. Comparison of an Inductance In-Line Oil Debris Sensor and Magnetic Plug Oil Debris Sensor

    Science.gov (United States)

    Dempsey, Paula J.; Tuck, Roger; Showalter, Stephen

    2012-01-01

    The objective of this research was to compare the performance of an inductance in-line oil debris sensor and magnetic plug oil debris sensor when detecting transmission component health in the same system under the same operating conditions. Both sensors were installed in series in the NASA Glenn Spiral Bevel Gear Fatigue Rig during tests performed on 5 gear sets (pinion/gear) when different levels of damage occurred on the gear teeth. Results of this analysis found both the inductance in-line oil debris sensor and magnetic plug oil debris sensor have benefits and limitations when detecting gearbox component damage.

  12. Temporal and spatial variability in thalweg profiles of a gravel-bed river

    Science.gov (United States)

    Madej, Mary Ann

    1999-01-01

    This study used successive longitudinal thalweg profiles in gravel-bed rivers to monitor changes in bed topography following floods and associated large sediment inputs. Variations in channel bed elevations, distributions of residual water depths, percentage of channel length occupied by riffles, and a spatial autocorrelation coefficient (Moran's I) were used to quantify changes in morphological diversity and spatial structure in Redwood Creek basin, northwestern California. Bed topography in Redwood Creek and its major tributaries consists primarily of a series of pools and riffles. The size, frequency and spatial distribution of the pools and riffles have changed significantly during the past 20 years. Following large floods and high sediment input in Redwood Creek and its tributaries in 1975, variation in channel bed elevations was low and the percentage of the channel length occupied by riffles was high. Over the next 20 years, variation in bed elevations increased while the length of channel occupied by riffles decreased. An index [(standard deviation of residual water depth/bankfull depth) × 100] was developed to compare variations in bed elevation over a range of stream sizes, with a higher index being indicative of greater morphological diversity. Spatial autocorrelation in the bed elevation data was apparent at both fine and coarse scales in many of the thalweg profiles and the observed spatial pattern of bed elevations was found to be related to the dominant channel material and the time since disturbance. River reaches in which forced pools dominated, and in which large woody debris and bed particles could not be easily mobilized, exhibited a random distribution of bed elevations. In contrast, in reaches where alternate bars dominated, and both wood and gravel were readily transported, regularly spaced bed topography developed at a spacing that increased with time since disturbance. This pattern of regularly spaced bed features was reversed

  13. Marine debris: global and regional impacts

    OpenAIRE

    Torres N,Daniel; Berguño B,Jorge

    2011-01-01

    A synthesis on the Marine Debris problem is given upon de basis of the general knowledge on the matter as well as that obtained at Cape Shirreff, Livingston Island, South Shetland, Antarctica. It is suggested to improve the database on marine debris through permanent scientific research as well as with monitoring activities. It is necessary to coordinate key groups to apply strategies to identify types, sources, amount, interactions and socio-economic aspects of this global and regional probl...

  14. Postdetonation nuclear debris for attribution.

    Science.gov (United States)

    Fahey, A J; Zeissler, C J; Newbury, D E; Davis, J; Lindstrom, R M

    2010-11-23

    On the morning of July 16, 1945, the first atomic bomb was exploded in New Mexico on the White Sands Proving Ground. The device was a plutonium implosion device similar to the device that destroyed Nagasaki, Japan, on August 9 of that same year. Recently, with the enactment of US public law 111-140, the "Nuclear Forensics and Attribution Act," scientists in the government and academia have been able, in earnest, to consider what type of forensic-style information may be obtained after a nuclear detonation. To conduct a robust attribution process for an exploded device placed by a nonstate actor, forensic analysis must yield information about not only the nuclear material in the device but about other materials that went into its construction. We have performed an investigation of glassed ground debris from the first nuclear test showing correlations among multiple analytical techniques. Surprisingly, there is strong evidence, obtainable only through microanalysis, that secondary materials used in the device can be identified and positively associated with the nuclear material.

  15. Modeling an Ice-rich Lobate Debris Apron in Deuteronilus Mensae

    Science.gov (United States)

    Fastook, J. L.; Head, J. W.; Madeleine, J.-B.; Forget, F.; Marchant, D.

    2010-03-01

    Models help interpret observed glacial deposits and test formation scenarios. We examine a lobate debris apron recently proven to contain pure water ice. Two hypotheses are tested: alcove-only and collapse from a larger ice sheet driven by a GCM.

  16. Global analysis of anthropogenic debris ingestion by sea turtles.

    Science.gov (United States)

    Schuyler, Qamar; Hardesty, Britta Denise; Wilcox, Chris; Townsend, Kathy

    2014-02-01

    Ingestion of marine debris can have lethal and sublethal effects on sea turtles and other wildlife. Although researchers have reported on ingestion of anthropogenic debris by marine turtles and implied incidences of debris ingestion have increased over time, there has not been a global synthesis of the phenomenon since 1985. Thus, we analyzed 37 studies published from 1985 to 2012 that report on data collected from before 1900 through 2011. Specifically, we investigated whether ingestion prevalence has changed over time, what types of debris are most commonly ingested, the geographic distribution of debris ingestion by marine turtles relative to global debris distribution, and which species and life-history stages are most likely to ingest debris. The probability of green (Chelonia mydas) and leatherback turtles (Dermochelys coriacea) ingesting debris increased significantly over time, and plastic was the most commonly ingested debris. Turtles in nearly all regions studied ingest debris, but the probability of ingestion was not related to modeled debris densities. Furthermore, smaller, oceanic-stage turtles were more likely to ingest debris than coastal foragers, whereas carnivorous species were less likely to ingest debris than herbivores or gelatinovores. Our results indicate oceanic leatherback turtles and green turtles are at the greatest risk of both lethal and sublethal effects from ingested marine debris. To reduce this risk, anthropogenic debris must be managed at a global level. © 2013 The Authors. Conservation Biology published by Wiley Periodicals, Inc., on behalf of the Society for Conservation Biology.

  17. A globally complete map of supraglacial debris cover and a new toolkit for debris cover research

    Science.gov (United States)

    Herreid, Sam; Pellicciotti, Francesca

    2017-04-01

    A growing canon of literature is focused on resolving the processes and implications of debris cover on glaciers. However, this work is often confined to a handful of glaciers that were likely selected based on criteria optimizing their suitability to test a specific hypothesis or logistical ease. The role of debris cover in a glacier system is likely to not go overlooked in forthcoming research, yet the magnitude of this role at a global scale has not yet been fully described. Here, we present a map of debris cover for all glacierized regions on Earth including the Greenland Ice Sheet using 30 m Landsat data. This dataset will begin to open a wider context to the high quality, localized findings from the debris-covered glacier research community and help inform large-scale modeling efforts. A global map of debris cover also facilitates analysis attempting to isolate first order geomorphological and climate controls of supraglacial debris production. Furthering the objective of expanding the inclusion of debris cover in forthcoming research, we also present an under development suite of open-source, Python based tools. Requiring minimal and often freely available input data, we have automated the mapping of: i) debris cover, ii) ice cliffs, iii) debris cover evolution over the Landsat era and iv) glacier flow instabilities from altered debris structures. At the present time, debris extent is the only globally complete quantity but with the expanding repository of high quality global datasets and further tool development minimizing manual tasks and computational cost, we foresee all of these tools being applied globally in the near future.

  18. Pebble-bed reactor

    International Nuclear Information System (INIS)

    Lohnert, G.; Mueller-Frank, U.; Heil, J.

    1976-01-01

    A pebble-bed nuclear reactor of large power rating comprises a container having a funnel-shaped bottom forming a pebble run-out having a centrally positioned outlet. A bed of downwardly-flowing substantially spherical nuclear fuel pebbles is positioned in the container and forms a reactive nuclear core maintained by feeding unused pebbles to the bed's top surface while used or burned-out pebbles run out and discharge through the outlet. A substantially conical body with its apex pointing upwardly and its periphery spaced from the periphery of the container spreads the bottom of the bed outwardly to provide an annular flow down the funnel-shaped bottom forming the runout, to the discharge outlet. This provides a largely constant downward velocity of the spheres throughout the diameter of the bed throughout a substantial portion of the down travel, so that all spheres reach about the same burned-out condition when they leave the core, after a single pass through the core area

  19. Fluidised bed heat exchangers

    International Nuclear Information System (INIS)

    Elliott, D.E.; Healey, E.M.; Roberts, A.G.

    1974-01-01

    Problems that have arisen during the initial stages of development of fluidised bed boilers in which heat transfer surfaces are immersed in fluidised solids are discussed. The very high heat transfer coefficients that are obtained under these conditions can be exploited to reduce the total heat transfer surface to a fraction of that in normal boilers. However, with the high heat flux levels involved, tube stressing becomes more important and it is advantageous to use smaller diameter tubes. One of the initial problems was that the pumping power absorbed by the fluidised bed appeared to be high. The relative influence of the fluidising velocity (and the corresponding bed area), tube diameter, tube spacing, heat transfer coefficient and bed temperature on pumping power and overall cost was determined. This showed the importance of close tube packing and research was undertaken to see if this would adversely affect the heat transfer coefficient. Pressure operation also reduces the pumping power. Fouling and corrosion tests in beds burning coal suggest that higher temperatures could be reached reliably and cost studies show that, provided the better refractory metals are used, the cost of achieving higher temperatures is not unduly high. It now remains to demonstrate at large scale that the proposed systems are viable and that the methods incorporated to overcome start up and part lead running problems are satisfactory. The promising role of these heat transfer techniques in other applications is briefly discussed

  20. Debris filtering effectiveness and pressure drop tests of debris resistance-bottom end piece

    International Nuclear Information System (INIS)

    Chung, Moon Ki; Song, Chul Hwa; Chung, Heung June; Won, Soon Yeun; Cho, Young Ro; Kim, Bok Deuk

    1992-03-01

    In this final report, described are the test conditions and test procedures for the debris filtering effectiveness and pressure drop tests for developing the Debris Resistance-Bottom End Piece (DR-BEP). And the test results are tabulated for later evaluation. (Author)

  1. Loopy, Floppy and Fragmented: Debris Characteristics Matter

    Science.gov (United States)

    Parrish, J.; Burgess, H. K.

    2016-02-01

    Marine debris is a world-wide problem threatening the health and safety of marine organisms, ecosystems, and humans. Recent and ongoing research shows that risk of harm is not associated with identity, but rather with a set of specific character states, where the character state space intersection is defined by the organism of interest. For example, intersections of material, color, rigidity and size predict the likelihood of an object being ingested: plastic, clear-white, floppy objects risks to sea turtles whereas yellow-red, rigid objects risks to albatrosses. A character state space approach allows prioritization of prevention and removal of marine debris informed by risk assessments for species of interest by comparing species ranges with spatio-temporal hotspots of all debris with characteristics known to be associated with increased risk of harm, regardless of identity. With this in mind, the Coastal Observation and Seabird Survey Team (COASST) developed and tested a 20 character data collection approach to quantifying the diversity and abundance of marine debris found on beaches. Development resulted in meta-analysis of the literature and expert opinion eliciting harmful character state space. Testing included data collection on inter-rater reliability and accuracy, where the latter included 75 participants quantifying marine debris characteristics on monthly surveys of 30 beaches along the Washington and Oregon coastlines over the past year. Pilot work indicates that characters must be simply and operationally defined, states must be listed, and examples must be provided for color states. Complex characters (e.g., windage, shape) are not replicable across multiple data collectors. Although data collection takes longer than other marine debris surveys for a given amount of debris and area surveyed, volunteer rapidity and accuracy improved within 3-5 surveys. Initial feedback indicated that volunteers were willing to continue collecting data as long as they

  2. in Spouted Bed

    Directory of Open Access Journals (Sweden)

    Bronislaw Buczek

    2013-01-01

    Full Text Available Samples of active coke, fresh and spent after cleaning flue gases from communal waste incinerators, were investigated. The outer layers of both coke particles were separately removed by comminution in a spouted bed. The samples of both active cokes were analysed by means of densities, mercury porosimetry, and adsorption technique. Remaining cores were examined to determine the degree of consumption of coke by the sorption of hazardous emissions (SO2, HCl, and heavy metals through its bed. Differences in contamination levels within the porous structure of the particles were estimated. The study demonstrated the effectiveness of commercial active coke in the cleaning of flue gases.

  3. Mixed debris treatment at the Idaho National Engineering Laboratory (INEL)

    International Nuclear Information System (INIS)

    Garcia, E.C.; Porter, C.L.; Wallace, M.T.

    1993-01-01

    August 18, 1992 the Environmental Protection Agency (EPA) published the final revised treatment standards for hazardous debris, including mixed debris. (1) Whereas previous standards had been concentration based, the revised standards are performance based. Debris must be treated prior to land disposal, using specific technologies from one or more of the following families of debris treatment technologies: Extraction, destruction, or immobilization. Seventeen specific technologies with generic application are discussed in the final rule. The existing capabilities and types of debris at the INEL were scrubbed against the debris rule to determine an overall treatment strategy. Seven types of debris were identified: combustible, porous, non-porous, inherently hazardous, HEPA filters, asbestos contaminated, and reactive metals contaminated debris. With the exception of debris contaminated with reactive metals treatment can be achieved utilizing existing facilities coupled with minor modifications

  4. Mixed debris treatment at the Idaho National Engineering Laboratory (INEL)

    International Nuclear Information System (INIS)

    Garcia, E.C.; Porter, C.L.; Wallace, M.T.

    1993-01-01

    August 18, 1992 the EPA published the final revised treatment standards for hazardous debris, including mixed debris. Whereas previous standards had been concentration based, the revised standards are performance based. Debris must be treated prior to land disposal, using specific technologies from one or more of the following families of debris treatment technologies: Extraction, destruction, or immobilization. Seventeen specific technologies with generic application are discussed in the final rule. The existing capabilities and types of debris at the INEL were evaluated against the debris rule to determine an overall treatment strategy for the INEL. Seven types of debris were identified: Combustible, porous, non-porous, inherently hazardous, HEPA filters, asbestos contaminated, and reactive metals contaminated debris. With the exception of debris contaminated with reactive metals treatment can be achieved utilizing existing facilities coupled with minor modifications

  5. The Safety of Hospital Beds

    Science.gov (United States)

    Gervais, Pierre; Pooler, Charlotte; Merryweather, Andrew; Doig, Alexa K.; Bloswick, Donald

    2015-01-01

    To explore the safety of the standard and the low hospital bed, we report on a microanalysis of 15 patients’ ability to ingress, move about the bed, and egress. The 15 participants were purposefully selected with various disabilities. Bed conditions were randomized with side rails up or down and one low bed with side rails down. We explored the patients’ use of the side rails, bed height, ability to lift their legs onto the mattress, and ability to turn, egress, and walk back to the chair. The standard bed was too high for some participants, both for ingress and egress. Side rails were used by most participants when entering, turning in bed, and exiting. We recommend that side rails be reconsidered as a means to facilitate in-bed movement, ingress, and egress. Furthermore, single deck height settings for all patients are not optimal. Low beds as a safety measure must be re-evaluated. PMID:28462302

  6. Debris flow analysis with a one dimensional dynamic run-out model that incorporates entrained material

    Science.gov (United States)

    Luna, Byron Quan; Remaître, Alexandre; van Asch, Theo; Malet, Jean-Philippe; van Westen, Cees

    2010-05-01

    Estimating the magnitude and the intensity of rapid landslides like debris flows is fundamental to evaluate quantitatively the hazard in a specific location. Intensity varies through the travelled course of the flow and can be described by physical features such as deposited volume, velocities, height of the flow, impact forces and pressures. Dynamic run-out models are able to characterize the distribution of the material, its intensity and define the zone where the elements will experience an impact. These models can provide valuable inputs for vulnerability and risk calculations. However, most dynamic run-out models assume a constant volume during the motion of the flow, ignoring the important role of material entrained along its path. Consequently, they neglect that the increase of volume enhances the mobility of the flow and can significantly influence the size of the potential impact area. An appropriate erosion mechanism needs to be established in the analyses of debris flows that will improve the results of dynamic modeling and consequently the quantitative evaluation of risk. The objective is to present and test a simple 1D debris flow model with a material entrainment concept based on limit equilibrium considerations and the generation of excess pore water pressure through undrained loading of the in situ bed material. The debris flow propagation model is based on a one dimensional finite difference solution of a depth-averaged form of the Navier-Stokes equations of fluid motions. The flow is treated as a laminar one phase material, which behavior is controlled by a visco-plastic Coulomb-Bingham rheology. The model parameters are evaluated and the model performance is tested on a debris flow event that occurred in 2003 in the Faucon torrent (Southern French Alps).

  7. Life and death of ice cliffs and lakes on debris covered glaciers - insights from a new dataset from the Nepalese Himalaya

    Science.gov (United States)

    Steiner, Jakob; Buri, Pascal; Miles, Evan; Ragettli, Silvan; Pellicciotti, Francesca

    2016-04-01

    Numerous studies suggest that supraglacial ice cliffs and lakes could be one contributing factor to relatively high overall ablation rates on debris covered glaciers. While some studies have quantified backwasting rates, developments over the larger scale have not yet been assessed. Field work and earlier studies during three seasons in the Langtang catchment in the Nepalese Himalaya has given some insights into how these landforms develop, from initial emergence to persistence and disappearance. From 6 sets of concurrent high-resolution satellite imagery and DEMs between 2006 and 2015 and an additional image from 1974, we assembled an extensive dataset of these landforms on all glaciers in the catchment, including nearly 4000 individual lakes and cliffs. We show that ice cliffs appear in combination with lakes or without and there are lakes that are not bordered by a cliff. Numbers vary strongly between seasons, especially as lakes show strong seasonal variability. There are furthermore different types of cliff forms - circular, lateral and longitudinal - that give an indication of their formation process. Circular cliffs form with either collapsing subglacial channels or overdeepenings caused by water accumulating on the surface, while lateral cliffs are likely associated with underlying crevasses. Some of the cliff and lake systems remain at the same location on-glacier over a number of years, while most move with the whole glacier body down valley. From the DEMs determine preferential slopes and expositions of the cliffs in the catchment which have been shown to be essential aspects in explaining the backwasting process. In combination with field observations from one glacier, where most of these types were present, we can infer development processes of a number of systems over the whole catchment. It is also apparent that densities of these landforms vary greatly over the glacier surface, which can be explained with velocities or underlying bed topography in

  8. Exploiting LSPIV to assess debris-flow velocities in the field

    Science.gov (United States)

    Theule, Joshua I.; Crema, Stefano; Marchi, Lorenzo; Cavalli, Marco; Comiti, Francesco

    2018-01-01

    The assessment of flow velocity has a central role in quantitative analysis of debris flows, both for the characterization of the phenomenology of these processes and for the assessment of related hazards. Large-scale particle image velocimetry (LSPIV) can contribute to the assessment of surface velocity of debris flows, provided that the specific features of these processes (e.g. fast stage variations and particles up to boulder size on the flow surface) are taken into account. Three debris-flow events, each of them consisting of several surges featuring different sediment concentrations, flow stages, and velocities, have been analysed at the inlet of a sediment trap in a stream in the eastern Italian Alps (Gadria Creek). Free software has been employed for preliminary treatment (orthorectification and format conversion) of video-recorded images as well as for LSPIV application. Results show that LSPIV velocities are consistent with manual measurements of the orthorectified imagery and with front velocity measured from the hydrographs in a channel recorded approximately 70 m upstream of the sediment trap. Horizontal turbulence, computed as the standard deviation of the flow directions at a given cross section for a given surge, proved to be correlated with surface velocity and with visually estimated sediment concentration. The study demonstrates the effectiveness of LSPIV in the assessment of surface velocity of debris flows and permit the most crucial aspects to be identified in order to improve the accuracy of debris-flow velocity measurements.

  9. Cetaceans and Marine Debris: The Great Unknown

    Directory of Open Access Journals (Sweden)

    Mark Peter Simmonds

    2012-01-01

    Full Text Available Plastics and other marine debris have been found in the gastrointestinal tracts of cetaceans, including instances where large quantities of material have been found that are likely to cause impairment to digestive processes and other examples, where other morbidity and even death have resulted. In some instances, debris may have been ingested as a result of the stranding process and, in others, it may have been ingested when feeding. Those species that are suction or “ram” feeders may be most at risk. There is also evidence of entanglement of cetaceans in marine debris. However, it is usually difficult to distinguish entanglement in active fishing gear from that in lost or discarded gear. The overall significance of the threat from ingested plastics and other debris remains unclear for any population or species of cetaceans, although there are concerns for some taxa, including at the population level, and marine debris in the oceans continues to grow. Further research including the compilation of unpublished material and the investigation of important habitat areas is strongly recommended.

  10. Apparatus for controlling fluidized beds

    Science.gov (United States)

    Rehmat, A.G.; Patel, J.G.

    1987-05-12

    An apparatus and process are disclosed for control and maintenance of fluidized beds under non-steady state conditions. An ash removal conduit is provided for removing solid particulates from a fluidized bed separate from an ash discharge conduit in the lower portion of the grate supporting such a bed. The apparatus and process of this invention is particularly suitable for use in ash agglomerating fluidized beds and provides control of the fluidized bed before ash agglomeration is initiated and during upset conditions resulting in stable, sinter-free fluidized bed maintenance. 2 figs.

  11. Stratigraphy, age and environments of the late Miocene Mpesida Beds, Tugen Hills, Kenya.

    Science.gov (United States)

    Kingston, John D; Fine Jacobs, Bonnie; Hill, Andrew; Deino, Alan

    2002-01-01

    Interpretations of faunal assemblages from the late Miocene Mpesida Beds in the Tugen Hills of the Central Kenyan Rift Valley have figured prominently in discussions of faunal turnover and establishment of the modern East African communities. These faunal changes have important implications for the divergence of the human lineage from the African apes ca. 8-5 Ma. While fossil material recovered from the Mpesida Beds has traditionally been analyzed collectively, accumulating evidence indicates that Mpesida facies span the 7-6 Ma interval and are scattered more than 25 km along the eastern flanks of the Tugen Hills. Stratigraphic distinctions between Mpesida facies and younger sediments in the sequence, such as the Lukeino Formation, are not yet fully resolved, further complicating temporal assessments and stratigraphic context of Mpesida facies. These issues are discussed with specific reference to exposures of Mpesida facies at Rurmoch, where large fossil tree fragments were swept up in an ancient ash flow. Preserved anatomical features of the fossil wood as well as estimated tree heights suggest a wet, lowland rainforest in this portion of the rift valley. Stable isotopic analyses of fossil enamel and paleosol components indicate the presence of more open habitats locally. Overlying air-fall tuffs and epiclastic debris, possibly associated with the ash flow, have yielded an assemblage of vertebrate fossils including two teeth belonging to one of the earliest colombines of typical body size known from Africa, after the rather small Microcolobus. Single-crystal, laser-fusion,(40)Ar/(39)Ar dates from a capping trachyte flow as well as tuffs just below the lava contact indicate an age of greater than 6.37 Ma for the fossil material. Copyright 2002 Academic Press.

  12. Fluidized bed calciner

    International Nuclear Information System (INIS)

    Sheely, W.F.

    1986-01-01

    A unique way to convert radioactive scrap into useful nuclear fuel products was developed for the Department of Energy at Hanford. An advanced, fluidized bed calciner is used to convert metallic nitrate scrap or waste solutions into benign, solid and gaseous products. There are broad potential applications of this concept beyond those in the nuclear industry

  13. Nail Bed Injuries

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Nail Bed Injuries Email to a friend * required ...

  14. Bed Bug Myths

    Science.gov (United States)

    Learn the truth about bed bugs, such as how easy they are to see with the naked eye, their preferred habitat, whether they transmit diseases, their public health effects, and whether pesticides are the best way to deal with an infestation.

  15. Numerical analysis of a heat-generating, truncated conical porous bed in a fluid-filled enclosure

    International Nuclear Information System (INIS)

    Chakravarty, Aranyak; Datta, Priyankan; Ghosh, Koushik; Sen, Swarnendu; Mukhopadhyay, Achintya

    2016-01-01

    Analysis of natural convection in enclosures containing heat generating porous medium has important applications related to geothermal, chemical, thermal and nuclear energy such as in-vessel cooling of debris beds in nuclear reactors, cooling of coal stockpiles etc. The objective of the present numerical study is to characterise the pattern of fluid flow and energy transfer during steady laminar natural convective flow in a cylindrical enclosure with a centrally placed heat generating porous bed. Flow through porous region is modelled using Darcy–Brinkmann–Forchheimer model and local thermal equilibrium is assumed for the porous region. Analysis is carried out for a wide range of Rayleigh number (Ra), Darcy number (Da) and thermal conductivity ratio, as well as for different bed geometries. It is observed that in addition to Ra and Da, the bed geometry also plays a very important role in determining flow field and temperature distribution within the enclosure. Interestingly, a significant change is observed in energy transfer mode from the porous bed corresponding to specific values of bed permeability and bed heat generation rate. This is characterised in terms of Ra and Da. Further, it is observed that this change in energy transfer mode is highly dependent on Ra. - Highlights: • Natural convection is analysed in an enclosure with a heat generating porous bed. • Effect of dimensionless parameters as well as bed geometry has been investigated. • Energy transfer mechanism from porous bed changes with dimensionless parameters. • Bed geometry significantly affects fluid flow and energy transfer in the enclosure.

  16. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Science.gov (United States)

    2010-01-01

    ... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that... minimum biobased content is 12 percent and shall be based on the amount of qualifying biobased carbon in..., and silk are not qualifying biobased feedstocks for the purpose of determining the biobased content of...

  17. Orbital debris: a technical assessment

    National Research Council Canada - National Science Library

    National Research Council Staff; Commission on Engineering and Technical Systems; Division on Engineering and Physical Sciences; National Research Council; National Academy of Sciences

    ... Systems National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1995 i Copyrightoriginal retained, the be not from cannot book, paper original however, for version formatting, authoritative the typesetting-specific created from the as publication files other XML and from this of recomposed styles, version heading print the breaks...

  18. VA National Bed Control System

    Data.gov (United States)

    Department of Veterans Affairs — The VA National Bed Control System records the levels of operating, unavailable and authorized beds at each VAMC, and it tracks requests for changes in these levels....

  19. Getting Rid of Bed Bugs

    Science.gov (United States)

    ... Directory Planning, Budget and Results Jobs and Internships Headquarters Offices Regional Offices Labs and Research Centers Bed ... to be careful in how you select a company. Related Information Collaborative Strategy on Bed Bugs - highlights ...

  20. Electrometallurgical treatment of TMI-2 fuel debris

    International Nuclear Information System (INIS)

    Karell, E.J.; Gourishankar, K.V.; Johnson, G.K.

    1997-01-01

    Argonne National Laboratory (ANL) has developed an electrometallurgical treatment process suitable for conditioning DOE oxide spent fuel for long-term storage or disposal. The process consists of an initial oxide reduction step that converts the actinide oxides to a metallic form, followed by an electrochemical separation of uranium from the other fuel constituents. The final product of the process is a uniform set of stable waste forms suitable for long-term storage or disposal. The suitability of the process for treating core debris from the Three Mile Island-2 (TMI-2) reactor is being evaluated. This paper reviews the results of preliminary experimental work performed using simulated TMI-2 fuel debris

  1. Debris impact on emergency coolant recirculation - summary and conclusions

    International Nuclear Information System (INIS)

    Jain, Bhagwat; Hsia, Anthony; Armand, Yves; Mattei, Jean-Marie; Hyvaerinen, Juhani; Maqua, Michael; Puetter, Bernhard; Sandervaag, Oddbjoern; Vandewalle, Andre; Tombuyses, Beatrice; Pyy, Pekka; Royen, Jacques

    2004-01-01

    protection. - Amount of latent debris (e.g. use of qualified coatings, size of unprotected ferritic surfaces, cleanliness regime after outages). - Chemical effects due to NaOH. c. Sump strainer clogging may substantially increase the total core damage frequency. This statement depends strongly on the design features mentioned above and the assumption made to estimate the amount of insulation material reaching the sump strainer and the resulting pressure loss. Presently, different assumptions are used in different countries regarding debris generation and transport. d. Timely resolution of the sump strainer clogging issue is essential. Some participants presented solutions to the problem based on: - new strainer designs; - reduction of insulation material generation; - development of strainer cleaning procedures e.g. back-flushing. e. Timely solutions to the sump strainer clogging problem are plant design specific and debris specific. f. Assessment methods should continue to be enhanced. However, some countries have developed solutions or implemented compensatory measures. g. Chemical effects have to be taken into account. h. Latent debris continues to be of concern. i. Thin bed effect is one of the major concerns impacting strainer head loss and core cooling

  2. Experimental study on evolution of bed structures of natural mountain rivers

    Directory of Open Access Journals (Sweden)

    Huai-xiang Liu

    2011-06-01

    Full Text Available Bed structures in many mountain rivers provide additional resistance to the flow. A field experiment was conducted on debris flow deposits in the valley of the Jiangjiagou Ravine, a tributary of the Yangtze River in southwestern China, to study the evolution and distribution of bed structures and their relationship with environmental conditions. Water and sediment from the Jiangjiagou main stream were diverted into the experimental channel. Several hydrological schemes were adopted to scour the channel until equilibrium was reached. During this process the evolutions of bed structures and channel configuration were investigated. The results indicate that stronger bed structures mean greater stream power consumption, greater resistance, and greater slope in a certain section when rivers are in dynamic equilibrium. Thus, to some extent the longitudinal profiles of channels can be determined by the distribution of bed structures. In natural cases, the strength and evolution of bed structures are under the influence of environmental conditions such as discharge and bed-load transportation rate. That is, given the same conditions, the same bed structure distribution and longitudinal profile can be predicted.

  3. Linking effects of anthropogenic debris to ecological impacts

    NARCIS (Netherlands)

    Browne, M.A.; Underwood, A.J.; Chapman, M.G.; Williams, R.; Thompson, R.C.; Franeker, van J.A.

    2015-01-01

    Accelerated contamination of habitats with debris has caused increased effort to determine ecological impacts. Strikingly, most work on organisms focuses on sublethal responses to plastic debris. This is controversial because (i) researchers have ignored medical insights about the mechanisms that

  4. Age, origin and evolution of Antarctic debris-covered glaciers: Implications for landscape evolution and long-term climate change

    Science.gov (United States)

    Mackay, Sean Leland

    Antarctic debris-covered glaciers are potential archives of long-term climate change. However, the geomorphic response of these systems to climate forcing is not well understood. To address this concern, I conducted a series of field-based and numerical modeling studies in the McMurdo Dry Valleys of Antarctica (MDV), with a focus on Mullins and Friedman glaciers. I used data and results from geophysical surveys, ice-core collection and analysis, geomorphic mapping, micro-meteorological stations, and numerical-process models to (1) determine the precise origin and distribution of englacial and supraglacial debris within these buried-ice systems, (2) quantify the fundamental processes and feedbacks that govern interactions among englacial and supraglacial debris, (3) establish a process-based model to quantify the inventory of cosmogenic nuclides within englacial and supraglacial debris, and (4) isolate the governing relationships between the evolution of englacial /supraglacial debris and regional climate forcing. Results from 93 field excavations, 21 ice cores, and 24 km of ground-penetrating radar data show that Mullins and Friedman glaciers contain vast areas of clean glacier ice interspersed with inclined layers of concentrated debris. The similarity in the pattern of englacial debris bands across both glaciers, along with model results that call for negligible basal entrainment, is best explained by episodic environmental change at valley headwalls. To constrain better the timing of debris-band formation, I developed a modeling framework that tracks the accumulation of cosmogenic 3He in englacial and supraglacial debris. Results imply that ice within Mullins Glacier increases in age non-linearly from 12 ka to ˜220 ka in areas of active flow (up to >> 1.6 Ma in areas of slow-moving-to-stagnant ice) and that englacial debris bands originate with a periodicity of ˜41 ka. Modeling studies suggest that debris bands originate in synchronicity with changes in

  5. Life in the "plastisphere": microbial communities on plastic marine debris.

    Science.gov (United States)

    Zettler, Erik R; Mincer, Tracy J; Amaral-Zettler, Linda A

    2013-07-02

    Plastics are the most abundant form of marine debris, with global production rising and documented impacts in some marine environments, but the influence of plastic on open ocean ecosystems is poorly understood, particularly for microbial communities. Plastic marine debris (PMD) collected at multiple locations in the North Atlantic was analyzed with scanning electron microscopy (SEM) and next-generation sequencing to characterize the attached microbial communities. We unveiled a diverse microbial community of heterotrophs, autotrophs, predators, and symbionts, a community we refer to as the "Plastisphere". Pits visualized in the PMD surface conformed to bacterial shapes suggesting active hydrolysis of the hydrocarbon polymer. Small-subunit rRNA gene surveys identified several hydrocarbon-degrading bacteria, supporting the possibility that microbes play a role in degrading PMD. Some Plastisphere members may be opportunistic pathogens (the authors, unpublished data) such as specific members of the genus Vibrio that dominated one of our plastic samples. Plastisphere communities are distinct from surrounding surface water, implying that plastic serves as a novel ecological habitat in the open ocean. Plastic has a longer half-life than most natural floating marine substrates, and a hydrophobic surface that promotes microbial colonization and biofilm formation, differing from autochthonous substrates in the upper layers of the ocean.

  6. Debris flow rheology: Experimental analysis of fine-grained slurries

    Science.gov (United States)

    Major, Jon J.; Pierson, Thomas C.

    1992-01-01

    The rheology of slurries consisting of ≤2-mm sediment from a natural debris flow deposit was measured using a wide-gap concentric-cylinder viscometer. The influence of sediment concentration and size and distribution of grains on the bulk rheological behavior of the slurries was evaluated at concentrations ranging from 0.44 to 0.66. The slurries exhibit diverse rheological behavior. At shear rates above 5 s−1 the behavior approaches that of a Bingham material; below 5 s−1, sand exerts more influence and slurry behavior deviates from the Bingham idealization. Sand grain interactions dominate the mechanical behavior when sand concentration exceeds 0.2; transient fluctuations in measured torque, time-dependent decay of torque, and hysteresis effects are observed. Grain rubbing, interlocking, and collision cause changes in packing density, particle distribution, grain orientation, and formation and destruction of grain clusters, which may explain the observed behavior. Yield strength and plastic viscosity exhibit order-of-magnitude variation when sediment concentration changes as little as 2–4%. Owing to these complexities, it is unlikely that debris flows can be characterized by a single rheological model.

  7. Interstellar Explorer Observations of the Solar System's Debris Disks

    Science.gov (United States)

    Lisse, C. M.; McNutt, R. L., Jr.; Brandt, P. C.

    2017-12-01

    Planetesimal belts and debris disks full of dust are known as the "signposts of planet formation" in exosystems. The overall brightness of a disk provides information on the amount of sourcing planetesimal material, while asymmetries in the shape of the disk can be used to search for perturbing planets. The solar system is known to house two such belts, the Asteroid belt and the Kuiper Belt; and at least one debris cloud, the Zodiacal Cloud, sourced by planetisimal collisions and Kuiper Belt comet evaporative sublimation. However these are poorly understood in toto because we live inside of them. E.g., while we know of the two planetesimal belt systems, it is not clear how much, if any, dust is produced from the Kuiper belt since the near-Sun comet contributions dominate near-Earth space. Understanding how much dust is produced in the Kuiper belt would give us a much better idea of the total number of bodies in the belt, especially the smallest ones, and their dynamical collisional state. Even for the close in Zodiacal cloud, questions remain concerning its overall shape and orientation with respect to the ecliptic and invariable planes of the solar system - they aren't explainable from the perturbations caused by the known planets alone. In this paper we explore the possibilities of using an Interstellar Explorer telescope placed at 200 AU from the sun to observe the brightness, shape, and extent of the solar system's debris disk(s). We should be able to measure the entire extent of the inner, near-earth zodiacal cloud; whether it connects smoothly into an outer cloud, or if there is a second outer cloud sourced by the Kuiper belt and isolated by the outer planets, as predicted by Stark & Kuchner (2009, 2010) and Poppe et al. (2012, 2016; Figure 1). VISNIR imagery will inform about the dust cloud's density, while MIR cameras will provide thermal imaging photometry related to the cloud's dust particle size and composition. Observing at high phase angle by looking

  8. Monitoring the abundance of plastic debris in the marine environment

    OpenAIRE

    Ryan, Peter G.; Moore, Charles J.; van Franeker, Jan A.; Moloney, Coleen L.

    2009-01-01

    Plastic debris has significant environmental and economic impacts in marine systems. Monitoring is crucial to assess the efficacy of measures implemented to reduce the abundance of plastic debris, but it is complicated by large spatial and temporal heterogeneity in the amounts of plastic debris and by our limited understanding of the pathways followed by plastic debris and its long-term fate. To date, most monitoring has focused on beach surveys of stranded plastics and other litter. Infreque...

  9. Property measurements and inner state estimation of simulated fuel debris

    Energy Technology Data Exchange (ETDEWEB)

    Hirooka, S.; Kato, M.; Morimoto, K.; Washiya, T. [Japan Atomic Energy Agency, Ibaraki (Japan)

    2014-07-01

    Fuel debris properties and inner state such as temperature profile were evaluated by using analysis of simulated fuel debris manufactured from UO{sub 2} and oxidized zircaloy. The center of the fuel debris was expected to be molten state soon after the melt down accident of LWRs because power density was very high. On the other hand, the surface of the fuel debris was cooled in the water. This large temperature gradient may cause inner stress and consequent cracks were expected. (author)

  10. Enviromental and Social Impact of the Pouring of Solid Waste and Debris About the Quality of the Medellin River and Some of its Affluents

    OpenAIRE

    Carvajal Flórez, Elizabeth; Ingeniera Ambiental Universidad Nacional de Colombia. Magíster en Ingeniería Universidad de Antioquia. Docente Institución Universitaria

    2009-01-01

    This research aims at evaluating the influence of the pouring of home solid waste and debris about the quality of the Medellin River and some of its main tributaries such as the La Hueso, La Iguaná and La García streams, under sanitary, environmental, and social criteria. A theoretical-practical method was used, which deals the issue of the inadequate disposal of home waste and debris on the hillsides and beds of streams being the object of the study, establishing in the social reality a trut...

  11. On the Solar System-Debris Disk Connecction

    OpenAIRE

    Moro-Martin, Amaya

    2007-01-01

    This paper emphasizes the connection between solar and extra-solar debris disks: how models and observations of the Solar System are helping us understand the debris disk phenomenon, and vice versa, how debris disks are helping us place our Solar System into context.

  12. Debris prevention system, radiation system, and lithograpic apparatus

    NARCIS (Netherlands)

    2009-01-01

    A debris prevention system is constructed and arranged to prevent debris that emanates from a radiation source from propagating with radiation from the radiation source into or within a lithographic apparatus. The debris prevention system includes an aperture that defines a maximum emission angle of

  13. Monitoring the abundance of plastic debris in the marine environment

    NARCIS (Netherlands)

    Ryan, P.G.; Moore, C.J. C.J.; Franeker, van J.A.; Moloney, C.L.

    2009-01-01

    Plastic debris has significant environmental and economic impacts in marine systems. Monitoring is crucial to assess the efficacy of measures implemented to reduce the abundance of plastic debris, but it is complicated by large spatial and temporal heterogeneity in the amounts of plastic debris and

  14. Conditioning of metallic Magnox fuel element debris

    International Nuclear Information System (INIS)

    Kaye, C.J.

    1983-01-01

    The conditioning of metallic Magnox debris poses particular problems arising from its chemical reactivity and from the presence in discrete amounts of highly radioactive components. The treatment of this waste is currently being studied by the Central Electricity Generating Board. Following retrieval from store it is envisaged that the debris will be dried and comminuted to facilitate the removal for further storage of the highly active components from the bulk debris. A satisfactory means of sorting the debris appears to be by magnetic induction. The relatively low activity but potentially reactive Magnox will then be directly encapsulated prior to disposal off-site. Currently the only disposal route open for this waste is to the deep ocean. Matrices for encapsulating Magnox have been developed and others are under investigation. The desirable features of such matrices include low chemical reactivity and impermeability to water. The methods used to characterize the resultant waste forms and the results obtained are presented. Thermosetting polymers produce suitable waste forms for sea disposal, exhibiting high mechanical strength and resistance to leaching, and possessing very low chemical reactivity with respect to the Magnox waste. Low viscosity matrices are advantageous from the point of view of the process plant engineering as they enable the comminuted waste to be directly encapsulated. (author)

  15. Europium-155 in Debris from Nuclear Weapons

    DEFF Research Database (Denmark)

    Aarkrog, Asker; Lippert, Jørgen Emil

    1967-01-01

    The lithium-drifted germanium detector enables determination of europium-155 on a routine basis in environmental samples contaminated with debris from nuclear weapons. From measurements of europium-155, cesium-144, and strontium-90 in air filters collected between 1961 and 1966, the yield...

  16. Numerical modeling of the debris flows runout

    Directory of Open Access Journals (Sweden)

    Federico Francesco

    2017-01-01

    Full Text Available Rapid debris flows are identified among the most dangerous of all landslides. Due to their destructive potential, the runout length has to be predicted to define the hazardous areas and design safeguarding measures. To this purpose, a continuum model to predict the debris flows mobility is developed. It is based on the well known depth-integrated avalanche model proposed by Savage and Hutter (S&H model to simulate the dry granular materials flows. Conservation of mass and momentum equations, describing the evolving geometry and the depth averaged velocity distribution, are re-written taking into account the effects of the interstitial pressures and the possible variation of mass along the motion due to erosion/deposition processes. Furthermore, the mechanical behaviour of the debris flow is described by a recently developed rheological law, which allows to take into account the dissipative effects of the grain inelastic collisions and friction, simultaneously acting within a ‘shear layer’, typically at the base of the debris flows. The governing PDEs are solved by applying the finite difference method. The analysis of a documented case is finally carried out.

  17. Plastic Debris Is a Human Health Issue

    NARCIS (Netherlands)

    Vethaak, A.D.; Leslie, H.A.

    2016-01-01

    The global threat of highly persistent plastic waste accumulating and fragmenting in the world’s oceans, inland waters and terrestrial environments is becoming increasingly evident.1−3 Humans are being exposed to both plastic particles and chemical additives being released from the plastic debris of

  18. TMI-2 core debris grab samples: Examination and analysis: Part 1

    International Nuclear Information System (INIS)

    Akers, D.W.; Carlson, E.R.; Cook, B.A.; Ploger, S.A.; Carlson, J.O.

    1986-09-01

    Six samples of particulate debris were removed from the TMI-2 core rubble bed during September and October 1983, and five more samples were obtained in March 1984. The samples (up to 174 g each) were obtained at two locations in the core: H8 (center) and E9 (mid-radius). Ten of the eleven samples were examined at the Idaho National Engineering Laboratory to obtain data on the physical and chemical nature of the debris and the postaccident condition of the core. Portions of the samples also were subjected to differential thermal analysis at Rockwell Hanford Operations and metallurgical and chemical examinations at Argonne National Laboratories. This report presents results of the examination of the core debris grab samples, including physical, metallurgical, chemical, and radiochemical analyses. The results indicate that temperatures in the core reached at least 3100 K during the TMI-2 accident, fuel melting and significant mixing of core structural material occurred, and large fractions of some radionuclides (e.g., 90 Sr and 144 Ce) were retained in the core

  19. Relations between red beds times and uranic mineralization at the area of north-west China, Shaanxi and Inner Mongolia

    International Nuclear Information System (INIS)

    Zhou Qiaosheng; Quan Zhigao

    1989-04-01

    Rad beds played an important role in the uranic mineralization. After analyzing the geological evolution in North-West China, Saanxi and Inner Mongolia the red beds is divided into six periods. The evolution rules at each period are studied. The authors found that the time of uranic mineralication and formation of red beds (basin) is simultaneously, the uranic deposits and red beds are accompanying minerals in all places existing deposits. Uranic mineralization is bound up with the continental red beds which was formed under dry and hot climate, but has no relations with the marine red beds. The place where the deposits exist, the red beds must exist, conversely it is not true. In the section, a big uranic deposit is generated only under or above the red beds. The relations between red beds and rich deposit are also explored. The mineralization theory and the model of uranic mineralization in red beds times are presented

  20. Optical Photometric Observations of GEO Debris

    Science.gov (United States)

    Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Edwin S.; Abercromby, Kira J.; Kelecy, Thomas M.; Horstman, Matt

    2010-01-01

    We report on a continuing program of optical photometric measurements of faint orbital debris at geosynchronous Earth orbit (GEO). These observations can be compared with laboratory studies of actual spacecraft materials in an effort to determine what the faint debris at GEO may be. We have optical observations from Cerro Tololo Inter-American Observatory (CTIO) in Chile of two samples of debris: 1. GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Curtis-Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 t11 magnitude that are discovered in the MODEST survey. 2. A smaller sample of high area to mass ratio (AMR) objects discovered independently, and acquired using predictions from orbits derived from independent tracking data collected days prior to the observations. Our optical observations in standard astronomical BVRI filters are done with either telescope, and with the telescope tracking the debris object at the object's angular rate. Observations in different filters are obtained sequentially. We have obtained 71 calibrated sequences of R-B-V-I-R magnitudes. A total of 66 of these sequences have 3 or more good measurements in all filters (not contaminated by star streaks or in Earth's shadow). Most of these sequences show brightness variations, but a small subset has observed brightness variations consistent with that expected from observational errors alone. The majority of these stable objects are redder than a solar color in both B-R and R-I. There is no dependence on color with brightness. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and

  1. Photometric Studies of GEO Orbital Debris

    Science.gov (United States)

    Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Ed; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the Cerro Tololo Inter- American Observatory (CTIO) 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R=15th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? More than 90 calibrated sequences of R-B-V-I-R magnitudes for a sample of 50 objects have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus the B-R color is a true measure of the surface of the debris piece facing the

  2. Laser space debris removal: now, not later

    Science.gov (United States)

    Phipps, Claude R.

    2015-02-01

    Small (1-10cm) debris in low Earth orbit (LEO) are extremely dangerous, because they spread the breakup cascade depicted in the movie "Gravity." Laser-Debris-Removal (LDR) is the only solution that can address both large and small debris. In this paper, we briefly review ground-based LDR, and discuss how a polar location can dramatically increase its effectiveness for the important class of sun-synchronous orbit (SSO) objects. No other solutions address the whole problem of large ( 1000cm, 1 ton) as well as small debris. Physical removal of small debris (by nets, tethers and so on) is impractical because of the energy cost of matching orbits. We also discuss a new proposal which uses a space-based station in low Earth orbit (LEO), and rapid, head-on interaction in 10- 40s rather than 4 minutes, with high-power bursts of 100ps, 355nm pulses from a 1.5m diameter aperture. The orbiting station employs "heat-capacity" laser mode with low duty cycle to create an adaptable, robust, dualmode system which can lower or raise large derelict objects into less dangerous orbits, as well as clear out the small debris in a 400-km thick LEO band. Time-average laser optical power is less than 15kW. The combination of short pulses and UV wavelength gives lower required energy density (fluence) on target as well as higher momentum coupling coefficient. This combination leads to much smaller mirrors and lower average power than the ground-based systems we have considered previously. Our system also permits strong defense of specific assets. Analysis gives an estimated cost of about 1k each to re-enter most small debris in a few months, and about 280k each to raise or lower 1-ton objects by 40km. We believe it can do this for 2,000 such large objects in about four years. Laser ablation is one of the few interactions in nature that propel a distant object without any significant reaction on the source.

  3. A novel mechanical model for phase-separation in debris flows

    Science.gov (United States)

    Pudasaini, Shiva P.

    2015-04-01

    Understanding the physics of phase-separation between solid and fluid phases as a two-phase mass moves down slope is a long-standing challenge. Here, I propose a fundamentally new mechanism, called 'separation-flux', that leads to strong phase-separation in avalanche and debris flows. This new model extends the general two-phase debris flow model (Pudasaini, 2012) to include a separation-flux mechanism. The new flux separation mechanism is capable of describing and controlling the dynamically evolving phase-separation, segregation, and/or levee formation in a real two-phase, geometrically three-dimensional debris flow motion and deposition. These are often observed phenomena in natural debris flows and industrial processes that involve the transportation of particulate solid-fluid mixture material. The novel separation-flux model includes several dominant physical and mechanical aspects that result in strong phase-separation (segregation). These include pressure gradients, volume fractions of solid and fluid phases and their gradients, shear-rates, flow depth, material friction, viscosity, material densities, boundary structures, gravity and topographic constraints, grain shape, size, etc. Due to the inherent separation mechanism, as the mass moves down slope, more and more solid particles are brought to the front, resulting in a solid-rich and mechanically strong frontal surge head followed by a weak tail largely consisting of the viscous fluid. The primary frontal surge head followed by secondary surge is the consequence of the phase-separation. Such typical and dominant phase-separation phenomena are revealed here for the first time in real two-phase debris flow modeling and simulations. However, these phenomena may depend on the bulk material composition and the applied forces. Reference: Pudasaini, Shiva P. (2012): A general two-phase debris flow model. J. Geophys. Res., 117, F03010, doi: 10.1029/2011JF002186.

  4. Study of dryout heat fluxes in beds of inductively heated particles

    International Nuclear Information System (INIS)

    Dhir, V.K.; Catton, I.

    1977-02-01

    Experimental observations of the dryout heat fluxes for inductively heated particulate beds have been made. The data were obtained when steel and lead particles in the size distribution 295-787 microns were placed in a 4.7 cm diameter pyrex glass jar and inductively heated by passing radio frequency current through a 13.3 cm diameter multi-turn work coil encircling the jar. Distilled water, methanol and acetone were used as coolants in the experiments, while the bed height was varied from 1.0 to 8.9 cm. Different mechanisms for the dryout in deep and shallow beds have been identified. Dryout in shallow beds is believed to occur when the vapor velocity in the gas jets exceeds a certain critical velocity at which choking of the vapor occurs, leading to obstruction in the flow of the liquid toward the bed. However, deep beds dry out when gravitational force can no longer maintain a downward coolant flow rate necessary to dissipate the heat generated in the bed. The heat flux data of the investigation and that from two previous investigations made at Argonne Laboratory and at UCLA have been correlated with semi-theoretical correlations based on the proposed hydrodynamic models. The deep and shallow bed correlations are used to predict the bed height at which transition from deep to shallow bed would occur. An application of the study has been made to determine the maximum coolable depths of the core debris as a function of the particle size, bed porosity and decay heat

  5. Debris flow cartography using differential GNSS and Theodolite measurements

    Science.gov (United States)

    Khazaradze, Giorgi; Guinau, Marta; Calvet, Jaume; Furdada, Gloria; Victoriano, Ane; Génova, Mar; Suriñach, Emma

    2016-04-01

    The presented results form part of a CHARMA project, which pursues a broad objective of reducing damage caused by uncontrolled mass movements, such as rockfalls, snow avalanches and debris flows. Ultimate goal of the project is to contribute towards the establishment of new scientific knowledge and tools that can help in the design and creation of early warning systems. Here we present the specific results that deal with the application of differential GNSS and classical geodetic (e.g. theodolite) methods for mapping debris and torrential flows. Specifically, we investigate the Portainé stream located in the Pallars Sobirà region of Catalonia (Spain), in the eastern Pyrenees. In the last decade more than ten debris-flow type phenomena have affected the region, causing considerable economic losses. Since early 2014, we have conducted several field campaigns within the study area, where we have employed a multi-disciplinary approach, consisting of geomorphological, dendro-chronological and geodetic methods, in order to map the river bed and reconstruct the history of the extreme flooding and debris flow events. Geodetic studies included several approaches, using the classical and satellite based methods. The former consisted of angle and distance measurements between the Geodolite 502 total station and the reflecting prisms placed on top of the control points located within the riverbed. These type of measurements are precise, although present several disadvantages such as the lack of absolute coordinates that makes the geo-referencing difficult, as well as a relatively time-consuming process that involves two persons. For this reason, we have also measured the same control points using the differential GNSS system, in order to evaluate the feasibility of replacing the total station measurements with the GNSS. The latter measuring method is fast and can be conducted by one person. However, the fact that the study area is within the riverbed, often below the trees

  6. The role of large woody debris in modulating the dispersal of a post-fire sediment pulse

    Science.gov (United States)

    Short, Lauren E.; Gabet, Emmanuel J.; Hoffman, Daniel F.

    2015-10-01

    In 2001, a series of post-fire debris flows brought 30,000 m3 of sediment, deposited as fans, to the narrow valley floor of Sleeping Child Creek in western Montana (USA). In 2005, pebble-counts and surveys of the channel in proximity to six of the debris flow fans documented a regular sequence of fine-grained aggradation upstream of the fans, incision through the fans, and coarse-grained aggradation downstream of the fans. These measurements were repeated in 2012. We found that the delivery of large woody debris (LWD) over the intervening 7 years has been a dominant factor in the disposition of the debris-flow material. The amount of LWD in the study reach has increased by as much as 50% in the areas with a high burn severity, leading to the formation of large logjams that interrupt the flow of sediment along the streambed. Nearly all of the surveyed reaches have aggraded since 2005, including those that had initially begun incising through the debris flow deposits, and the streambed has become generally finer. We hypothesize that, over the next few decades, debris flow sediment not colonized and anchored by riparian vegetation will trickle out of the affected reaches as the logjams slowly degrade.

  7. Sediment delivery in debris-flow torrents: two case studies in the Italian Alps

    Science.gov (United States)

    Bertoldi, Gabriele; Vincenzo, D'Agostino

    2013-04-01

    stream length of 1.4 km downstream of the source areas. Topographical survey of these cross sections have been repeated periodically regardless the occurrence of rainstorm events, so directly detecting morphological changes and tracks of new flow depths on the banks. To monitor the recharging rates from the hillslopes surrounding the channel, some sediment traps have been also installed in the Rio Rudan and in the Rio Gadria (8 and 6 sediment traps respectively). Thanks to the time comparison of the cross sections under observation a sediment budget was conducted both for successive flood events and/or for silent periods. This budget has been related to morphological, geometric and flow dependent variables in order to detect the forcing and, in case it exists, a trend of the phenomena. The debris recharge of the channels from the directly connected sediment source areas resulted lowly dependent on the rain storms causing debris flows, and more related with the year rainfall, local bank instabilities and failures, which might be amplified by the channel bed moisture before/after the debris-flow occurrence.

  8. NASA's New Orbital Debris Engineering Model, ORDEM2010

    Science.gov (United States)

    Krisko, Paula H.

    2010-01-01

    This paper describes the functionality and use of ORDEM2010, which replaces ORDEM2000, as the NASA Orbital Debris Program Office (ODPO) debris engineering model. Like its predecessor, ORDEM2010 serves the ODPO mission of providing spacecraft designers/operators and debris observers with a publicly available model to calculate orbital debris flux by current-state-of-knowledge methods. The key advance in ORDEM2010 is the input file structure of the yearly debris populations from 1995-2035 of sizes 10 micron - 1 m. These files include debris from low-Earth orbits (LEO) through geosynchronous orbits (GEO). Stable orbital elements (i.e., those that do not randomize on a sub-year timescale) are included in the files as are debris size, debris number, material density, random error and population error. Material density is implemented from ground-test data into the NASA breakup model and assigned to debris fragments accordingly. The random and population errors are due to machine error and uncertainties in debris sizes. These high-fidelity population files call for a much higher-level model analysis than what was possible with the populations of ORDEM2000. Population analysis in the ORDEM2010 model consists of mapping matrices that convert the debris population elements to debris fluxes. One output mode results in a spacecraft encompassing 3-D igloo of debris flux, compartmentalized by debris size, velocity, pitch, and yaw with respect to spacecraft ram direction. The second output mode provides debris flux through an Earth-based telescope/radar beam from LEO through GEO. This paper compares the new ORDEM2010 with ORDEM2000 in terms of processes and results with examples of specific orbits.

  9. Statistical description of flume experiments on mixed-size bed-load transport and bed armoring processes

    Science.gov (United States)

    Chen, D.; Zhang, Y.

    2008-12-01

    The objective of this paper is to describe the statistical properties of experiments on non-uniform bed-load transport as well as the mechanism of bed armoring processes. Despite substantial effort made over the last two decades, the ability to compute the bed-load flux in a turbulent system remains poor. The major obstacles include the poor understanding of the formation of armor lays on bed surfaces. Such a layer is much flow-resistible than the underlying material and therefore significantly inhibits sediment transport from the reach. To study the problem, we conducted a flume study for mixed sand/gravel sediments. We observed that aggregated sediment blocks were the most common characters in armor layers - the largest sizes resist hydraulic forces, while the smaller sizes add interlocking support and prevent loss of fine material through gaps between the larger particles. Fractional transport rates with the existing of armor layers were measured with time by sediment trapping method at the end of flume. To address the intermittent and time-varying behavior of bed-load transport during bed armoring processes, we investigated the probability distribution of the fractional bed-load transport rates, and the underlying dynamic model derived from the continuous time random walk framework. Results indicate that it is critical to consider the impact of armor layers when a flow is sufficient to move some of the finer particles and yet insufficient to move all the larger particles on a channel bed.

  10. SCDAP/RELAP5 modeling of fluid heat transfer and flow losses through porous debris in a light water reactor

    International Nuclear Information System (INIS)

    Harvego, E. A.; Siefken, L. J.

    2000-01-01

    The SCDAP/RELAP5 code is being developed at the Idaho National Engineering and Environmental Laboratory under the primary sponsorship of the U.S. Nuclear Regulatory Commission (NRC) to provide best-estimate transient simulations of light water reactor coolant systems during severe accidents. This paper describes the modeling approach used in the SCDAP/RELAP5 code to calculate fluid heat transfer and flow losses through porous debris that has accumulated in the vessel lower head and core regions during the latter stages of a severe accident. The implementation of heat transfer and flow loss correlations into the code is discussed, and calculations performed to assess the validity of the modeling approach are described. The different modes of heat transfer in porous debris include: (1) forced convection to liquid, (2) forced convection to gas, (3) nucleate boiling, (4) transition boiling, (5) film boiling, and (6) transition from film boiling to convection to vapor. The correlations for flow losses in porous debris include frictional and form losses. The correlations for flow losses were integrated into the momentum equations in the RELAP5 part of the code. Since RELAP5 is a very general non-homogeneous non-equilibrium thermal-hydraulics code, the resulting modeling methodology is applicable to a wide range of debris thermal-hydraulic conditions. Assessment of the SCDAP/RELAP5 debris bed thermal-hydraulic models included comparisons with experimental measurements and other models available in the open literature. The assessment calculations, described in the paper, showed that SCDAP/RELAP5 is capable of calculating the heat transfer and flow losses occurring in porous debris regions that may develop in a light water reactor during a severe accident

  11. Susceptibility assessment of debris flows using the analytic hierarchy process method − A case study in Subao river valley, China

    Directory of Open Access Journals (Sweden)

    Xingzhang Chen

    2015-08-01

    Full Text Available Many debris flows have occurred in the areas surrounding the epicenter of the Wenchuan earthquake. Susceptibility assessment of debris flows in this area is especially important for disaster prevention and mitigation. This paper studies one of the worst hit areas, the Subao river valley, and the susceptibility assessment of debris flows is performed based on field surveys and remote sensing interpretation. By investigating the formation conditions of debris flows in the valley, the following assessment factors are selected: mixture density of landslides and rock avalanches, distance to the seismogenic fault, stratum lithology, ground roughness, and hillside angle. The weights of the assessment factors are determined by the analytic hierarchy process (AHP method. Each of the assessment factors is further divided into five grades. Then, the assessment model is built using the multifactor superposition method to assess the debris flow susceptibility. Based on the assessment results, the Subao river valley is divided into three areas: high susceptibility areas, medium susceptibility areas, and low susceptibility areas. The high susceptibility areas are concentrated in the middle of the valley, accounting for 17.6% of the valley area. The medium susceptibility areas are in the middle and lower reaches, most of which are located on both sides of the high susceptibility areas and account for 45.3% of the valley area. The remainders are classified as low susceptibility areas. The results of the model are in accordance with the actual debris flow events that occurred after the earthquake in the valley, confirming that the proposed model is capable of assessing the debris flow susceptibility. The results can also provide guidance for reconstruction planning and debris flow prevention in the Subao river valley.

  12. Validation of new empirical model for self-leveling behavior of cylindrical particle beds based on experimental database

    International Nuclear Information System (INIS)

    Morita, Koji; Matsumoto, Tatsuya; Taketa, Shohei; Nishi, Shinpei; Cheng, Songbai; Suzuki, Tohru; Tobita, Yoshiharu

    2014-01-01

    During a material relocation phase of core disruptive accidents (CDAs) in sodium cooled fast reactors (SFRs), debris beds can be formed in the lower plenum region due to rapid quenching and fragmentation of molten core materials. Heat removal from debris beds is crucial to achieve so called in-vessel retention (IVR) of degraded core materials. Coolant boiling in the beds may lead to leveling of their mound shape, and then changes coolability of the beds with decay heat as well as neutronic characteristics. To clarify the mechanisms underlying this self-leveling behavior, several series of experiments using simulant materials has been performed in collaboration between Japan Atomic Energy Agency (JAEA) and Kyushu University in Japan. In the present study, experiments in a cylindrical system were employed to develop experimental data on self-leveling process of particle beds. In the experiments, to simulate the coolant boiling due to the decay heat in fuel, nitrogen gas was percolated uniformly through the bottom of the particle bed with a conical shape mound using a gas injection method. Time variations in bed height during the self-leveling process were measured for key experimental parameters on particle size, density and sphericity, and gas flow rate. Using a dimensional analysis approach, a new model was proposed to correlate the experimental data on transient bed height with an empirical equation using a characteristic time of self-leveling development and a terminal equilibrium height of the bed. It was demonstrated that the proposed model predicts self-leveling development of particle beds with reasonable accuracy in the present ranges of experimental conditions. (author)

  13. Protecting AREVA ATRIUM™ BWR fuel from debris fretting failure

    International Nuclear Information System (INIS)

    Cole, Steven E.; Garner, Norman L.; Lippert, Hans-Joachim; Graebert, Rüdiger; Mollard, Pierre; Hahn, Gregory C.

    2014-01-01

    Historically, debris fretting has been the leading cause of fuel rod failure in BWR fuel assemblies, costing the industry millions of dollars in lost generation and negatively impacting the working area of plant site personnel. In this paper the focus will be on recent BWR fuel product innovation designed to eliminate debris related failures. Experience feedback from more than three decades of operation history with non-line-of-sight FUELGUARD™ lower tie plate debris filters will be presented. The development and relative effectiveness of successive generations of filtration technology will be discussed. It will be shown that modern, state of the art debris filters are an effective defense against debris fretting failure. Protective measures extend beyond inlet nozzle debris filters. The comprehensive debris resistance features built into AREVA’s newest fuel design, the ATRIUM™ 11, reduce the overall risk of debris entrapment as well as providing a degree of protection from debris that may fall down on the fuel assembly from above, e.g., during refueling operations. The positive recent experience in a debris sensitive plant will be discussed showing that the combination of advanced fuel technology and a robust foreign material exclusion program at the reactor site can eliminate the debris fretting failure mechanism. (author)

  14. Space Transportation System Liftoff Debris Mitigation Process Overview

    Science.gov (United States)

    Mitchell, Michael; Riley, Christopher

    2011-01-01

    Liftoff debris is a top risk to the Space Shuttle Vehicle. To manage the Liftoff debris risk, the Space Shuttle Program created a team with in the Propulsion Systems Engineering & Integration Office. The Shutt le Liftoff Debris Team harnesses the Systems Engineering process to i dentify, assess, mitigate, and communicate the Liftoff debris risk. T he Liftoff Debris Team leverages off the technical knowledge and expe rtise of engineering groups across multiple NASA centers to integrate total system solutions. These solutions connect the hardware and ana lyses to identify and characterize debris sources and zones contribut ing to the Liftoff debris risk. The solutions incorporate analyses sp anning: the definition and modeling of natural and induced environmen ts; material characterizations; statistical trending analyses, imager y based trajectory analyses; debris transport analyses, and risk asse ssments. The verification and validation of these analyses are bound by conservative assumptions and anchored by testing and flight data. The Liftoff debris risk mitigation is managed through vigilant collab orative work between the Liftoff Debris Team and Launch Pad Operation s personnel and through the management of requirements, interfaces, r isk documentation, configurations, and technical data. Furthermore, o n day of launch, decision analysis is used to apply the wealth of ana lyses to case specific identified risks. This presentation describes how the Liftoff Debris Team applies Systems Engineering in their proce sses to mitigate risk and improve the safety of the Space Shuttle Veh icle.

  15. [Research progress in post-fire debris flow].

    Science.gov (United States)

    Di, Xue-ying; Tao, Yu-zhu

    2013-08-01

    The occurrence of the secondary disasters of forest fire has significant impacts on the environment quality and human health and safety. Post-fire debris flow is one of the most hazardous secondary disasters of forest fire. To understand the occurrence conditions of post-fire debris flow and to master its occurrence situation are the critical elements in post-fire hazard assessment. From the viewpoints of vegetation, precipitation threshold and debris flow material sources, this paper elaborated the impacts of forest fire on the debris flow, analyzed the geologic and geomorphic conditions, precipitation and slope condition that caused the post-fire debris flow as well as the primary mechanisms of debris-flow initiation caused by shallow landslide or surface runoff, and reviewed the research progress in the prediction and forecast of post-fire debris flow and the related control measures. In the future research, four aspects to be focused on were proposed, i. e., the quantification of the relationships between the fire behaviors and environmental factors and the post-fire debris flow, the quantitative research on the post-fire debris flow initiation and movement processes, the mechanistic model of post-fire debris flow, and the rapid and efficient control countermeasures of post-fire debris flow.

  16. Coal Bed Methane Primer

    Energy Technology Data Exchange (ETDEWEB)

    Dan Arthur; Bruce Langhus; Jon Seekins

    2005-05-25

    During the second half of the 1990's Coal Bed Methane (CBM) production increased dramatically nationwide to represent a significant new source of income and natural gas for many independent and established producers. Matching these soaring production rates during this period was a heightened public awareness of environmental concerns. These concerns left unexplained and under-addressed have created a significant growth in public involvement generating literally thousands of unfocused project comments for various regional NEPA efforts resulting in the delayed development of public and fee lands. The accelerating interest in CBM development coupled to the growth in public involvement has prompted the conceptualization of this project for the development of a CBM Primer. The Primer is designed to serve as a summary document, which introduces and encapsulates information pertinent to the development of Coal Bed Methane (CBM), including focused discussions of coal deposits, methane as a natural formed gas, split mineral estates, development techniques, operational issues, producing methods, applicable regulatory frameworks, land and resource management, mitigation measures, preparation of project plans, data availability, Indian Trust issues and relevant environmental technologies. An important aspect of gaining access to federal, state, tribal, or fee lands involves education of a broad array of stakeholders, including land and mineral owners, regulators, conservationists, tribal governments, special interest groups, and numerous others that could be impacted by the development of coal bed methane. Perhaps the most crucial aspect of successfully developing CBM resources is stakeholder education. Currently, an inconsistent picture of CBM exists. There is a significant lack of understanding on the parts of nearly all stakeholders, including industry, government, special interest groups, and land owners. It is envisioned the Primer would being used by a variety of

  17. Infant's bed climate and bedding in the Japanese home.

    Science.gov (United States)

    Nakamura Ikeda, Rie; Fukai, Kiyoko; Okamoto Mizuno, Kazue

    2012-06-01

    to assess the bed climate of infants in their homes in Japan. descriptive, exploratory, non-experimental research design. the data were collected at the participants' homes under normal circumstances. nineteen healthy infants between the ages of two and five months. Their mothers, who joined a parenting class organised by a maternity clinic in Okayama, Japan, consented to participate in this study. we visited the infants' homes and interviewed their mothers concerning the types and use of bedding. The temperature and relative humidity of the bed climate at the back and foot of the bedding, and in the room were measured every minute for four consecutive days. Differences among the bed climates measured during three seasons (spring, summer, and autumn) were assessed by one-way analysis of variance. The bed temperature was higher for infants than for adults. No significant difference in temperature was noted among the three seasons. The bed temperature was about 36.0°C when waterproof sheets and futon mattresses for children or adult were used. The average relative humidity of the bed climate at the back was highest in summer, followed by that in spring and autumn; the differences were significant. The use of waterproof sheets and futon mattresses for children in summer increased the relative humidity to 80% or more. The use of infant beds, sunoko drainboards, and cotton futon mattresses in summer was effective in reducing the bed humidity. these results suggest that nurse-midwives should advise the parents on comfortable bed climates for their infants, as well as how to select and use bedding for them. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Particle bed reactor modeling

    Science.gov (United States)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  19. Fluidised bed cereal cooking

    International Nuclear Information System (INIS)

    Jenkins, Simon Anthony

    2002-01-01

    Man has been cooking food for thousands of years for a number of reasons: to improve flavour and palatability, sterilise, increase digestibility, improve texture and colour. Increasingly more advanced techniques are employed today in food production plants to engineer foods with many different properties. With this in mind manufacturers are constantly seeking to improve processing techniques and apply new or different technologies (such as microwaves, RF and extrusion) to develop foods with new properties (like puffed texture starches) and to increase process efficiencies (energy efficiency, water reduction). This thesis reports on work undertaken to demonstrate the potential to achieve high temperature starch conversion of whole wheat grains in a fluidised bed, thereby reducing the amount of water required and processing time. Specifically, wheat from the farm at 14% water content is cooked in a fluidised bed. The fluidised bed heats the wheat quickly by convective heating. In addition, energy can be delivered directly to the grain by microwave heating during fluidisation. Degree of starch conversion is determined by measuring the reduction in size of endotherm of reaction as observed by Differential Scanning Calorimetry. The fluidising gas, processing temperature and starting moisture content were varied in order to investigate their effect on the cooking process. A mathematical model based on energy and species concentration equations was developed to help understand the internal grain processes. The model coupled the thermal energy equation with water diffusion. The effect of water evaporation was represented as a thermal sink in the energy equation. Popular kinetic models from literature were adapted to predict the degree of starch conversion. The model gives solutions consistent with experimental data and physical intuition. A commercial computational fluid dynamics package was used to study simple airflow and particle tracks in the fluidisation column. A

  20. Impact Forces from Tsunami-Driven Debris

    Science.gov (United States)

    Ko, H.; Cox, D. T.; Riggs, H.; Naito, C. J.; Kobayashi, M. H.; Piran Aghl, P.

    2012-12-01

    Debris driven by tsunami inundation flow has been known to be a significant threat to structures, yet we lack the constitutive equations necessary to predict debris impact force. The objective of this research project is to improve our understanding of, and predictive capabilities for, tsunami-driven debris impact forces on structures. Of special interest are shipping containers, which are virtually everywhere and which will float even when fully loaded. The forces from such debris hitting structures, for example evacuation shelters and critical port facilities such as fuel storage tanks, are currently not known. This research project focuses on the impact by flexible shipping containers on rigid columns and investigated using large-scale laboratory testing. Full-scale in-air collision experiments were conducted at Lehigh University with 20 ft shipping containers to experimentally quantify the nonlinear behavior of full scale shipping containers as they collide into structural elements. The results from the full scale experiments were used to calibrate computer models and used to design a series of simpler, 1:5 scale wave flume experiments at Oregon State University. Scaled in-air collision tests were conducted using 1:5 scale idealized containers to mimic the container behavior observed in the full scale tests and to provide a direct comparison to the hydraulic model tests. Two specimens were constructed using different materials (aluminum, acrylic) to vary the stiffness. The collision tests showed that at higher speeds, the collision became inelastic as the slope of maximum impact force/velocity decreased with increasing velocity. Hydraulic model tests were conducted using the 1:5 scaled shipping containers to measure the impact load by the containers on a rigid column. The column was instrumented with a load cell to measure impact forces, strain gages to measure the column deflection, and a video camera was used to provide the debris orientation and speed. The

  1. An Analysis of the Ecology and Public Perception of Coarse Woody Debris in Virginia

    OpenAIRE

    Fuhrman, Nicholas E.

    2004-01-01

    Coarse woody debris (CWD) is an important habitat component for wildlife, fish, and plants and is important in nutrient cycling and soil formation. Knowledge of the volume, distribution, and use of CWD across Virginia would be useful to forest managers modeling nutrient budgets in southeastern forests and is important to wildlife management efforts. Knowledge of the effectiveness of informational brochures and cooperative learning activities/presentations at influencing public perception of C...

  2. Threats to U.S. National Security Interests in Space: Orbital Debris Mitigation and Removal

    Science.gov (United States)

    2014-01-08

    Analytical Graphics, Inc., offers SOCRATES —Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space—on pending conjunctions over...the coming week. SOCRATES predicted a close approach between Iridium 33 and Cosmos 2251 of 584 m (1,916 ft.) at the time of the actual collision and... methods to slow or stop the formation of a debris belt. Donald J. Kessler and Burton G. Cour-Palais, “Collision Frequency of Artificial Satellites: The

  3. Counter-orbiting tidal debris as the origin of the MW DoS

    Directory of Open Access Journals (Sweden)

    Pawlowski M.S.

    2012-02-01

    Full Text Available The Milky Way satellite galaxies show a phase-space distribution that is not expected from the standard scenario of galaxy formation. This is a strong hint at them being of tidal origin, which would naturally explain their spacial distribution in a disc of satellites. It is shown that also their orbital directions can be reproduced with the debris of galaxy collisions. Both co- and counter-orbiting satellites are formed naturally in merger and fly-by interactions.

  4. Warm Debris Disk Candidates from WISE

    Science.gov (United States)

    Padgett, Deborah; Stapelfeldt, Karl; Liu, Wilson; Leisawitz, David

    2011-01-01

    The Wide Field Infrared Survey Explorer (WISE) has just completed a sensitive all-sky survey in photometric bands at 3.4, 4.6, 12, and 22 microns. We report on a preliminary investigation of main sequence Hipparcos and Tycho catalog stars with 22 micron emission in excess of photospheric levels. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets and is preferentially found in young systems with ages warm debris disk candidates are detected among FGK stars and 150 A stars within 120 pc. We are in the process of obtaining spectra to determine spectral types and activity level of these stars and are using HST, Herschel and Keck to characterize the dust, multiplicity, and substellar companions of these systems. In this contribution, we will discuss source selection methods and individual examples from among the WISE debris disk candidates.

  5. Rocky Planetary Debris Around Young WDs

    Science.gov (United States)

    Gaensicke, B.

    2014-04-01

    The vast majority of all known planet host stars, including the Sun, will eventually evolve into red giants and finally end their lives as white dwarfs: extremely dense Earth-sized stellar embers. Only close-in planets will be devoured during the red-giant phase. In the solar system, Mars, the asteroid belt, and all the giant planets will escape evaporation, and the same is true for many of the known exo-planets. It is hence certain that a significant fraction of the known white dwarfs were once host stars to planets, and it is very likely that many of them still have remnants of planetary systems. The detection of metals in the atmospheres of white dwarfs is the unmistakable signpost of such evolved planetary systems. The strong surface gravity of white dwarfs causes metals to sink out of the atmosphere on time-scales much shorter than their cooling ages, leading unavoidably to pristine H/He atmospheres. Therefore any metals detected in the atmosphere of a white dwarf imply recent or ongoing accretion of planetary debris. In fact, planetary debris is also detected as circumstellar dust and gas around a number of white dwarfs. These debris disks are formed from the tidal disruption of asteroids or Kuiper belt-like objects, stirred up by left-over planets, and are subsequently accreted onto the white dwarf, imprinting their abundance pattern into its atmosphere. Determining the photospheric abundances of debris-polluted white dwarfs is hence entirely analogue to the use of meteorites, "rocks that fell from the sky", for measuring the abundances of planetary material in the solar system. I will briefly review this new field of exo-planet science, and then focus on the results of a large, unbiased COS snapshot survey of relatively young ( 20-100Myr) white dwarfs that we carried out in Cycle 18/19. * At least 30% of all white dwarfs in our sample are accreting planetary debris, and that fraction may be as high as 50%. * In most cases where debris pollution is detected

  6. Debris Dispersion Model Using Java 3D

    Science.gov (United States)

    Thirumalainambi, Rajkumar; Bardina, Jorge

    2004-01-01

    This paper describes web based simulation of Shuttle launch operations and debris dispersion. Java 3D graphics provides geometric and visual content with suitable mathematical model and behaviors of Shuttle launch. Because the model is so heterogeneous and interrelated with various factors, 3D graphics combined with physical models provides mechanisms to understand the complexity of launch and range operations. The main focus in the modeling and simulation covers orbital dynamics and range safety. Range safety areas include destruct limit lines, telemetry and tracking and population risk near range. If there is an explosion of Shuttle during launch, debris dispersion is explained. The shuttle launch and range operations in this paper are discussed based on the operations from Kennedy Space Center, Florida, USA.

  7. Community Based Warning and Evacuation System against Debris Flow in the Upper Jeneberang River, Gowa, South Sulawesi

    Directory of Open Access Journals (Sweden)

    Sutikno Hardjosuwarno

    2008-07-01

    field and sand mining. It was also resulted that at the elevation of 700 m to the upper stream, the arrival time of debris flow is too short (< 3 minutes, it means that there is no time to evacuate when debris flow occurs. There are enough time to evacuate along the reaches between 700 m to 390 m and more time to evacuate along the downstream of 390 m river bed elevation due to the longer arrival time of debris flow. The existing community based warning system against debris flow uses radio transceiver to communicate between post and uses kentongan and sirens to propagate the warning message to inhabitants. Based on the sound test conducted in Jeneberang River, the manual siren has a coverage of 160 m to 600 m and it can be used in the warning system, being co-existence with the kentongan which has been used for a long time. In order to keep the community based warning system well functioned, it is recommended to synergize between the Local Government of Gowa Regency and the other stake holders with the inhabitants along Jeneberang River and the Sabo Community of Jeneberang in the operation and maintenance of the system.

  8. Fluidized bed boiler feed system

    Science.gov (United States)

    Jones, Brian C.

    1981-01-01

    A fluidized bed boiler feed system for the combustion of pulverized coal. Coal is first screened to separate large from small particles. Large particles of coal are fed directly to the top of the fluidized bed while fine particles are first mixed with recycled char, preheated, and then fed into the interior of the fluidized bed to promote char burnout and to avoid elutriation and carryover.

  9. A numerical modeling investigation of erosion and debris flows following the 2016 Fish Fire in the San Gabriel Mountains, CA, USA

    Science.gov (United States)

    Tang, H.; McGuire, L.; Rengers, F. K.; Kean, J. W.; Staley, D. M.

    2017-12-01

    Wildfire significantly changes the hydrological characteristics of soil for a period of several years and increases the likelihood of flooding and debris flows during high-intensity rainfall in steep watersheds. Hazards related to post-fire flooding and debris flows increase as populations expand into mountainous areas that are susceptible to wildfire, post-wildfire flooding, and debris flows. However, our understanding of post-wildfire debris flows is limited due to a paucity of direct observations and measurements, partially due to the remote locations where debris flows tend to initiate. In these situations, numerical modeling becomes a very useful tool for studying post-wildfire debris flows. Research based on numerical modeling improves our understanding of the physical mechanisms responsible for the increase in erosion and consequent formation of debris flows in burned areas. In this contribution, we study changes in sediment transport efficiency with time since burning by combining terrestrial laser scanning (TLS) surveys of a hillslope burned during the 2016 Fish Fire with numerical modeling of overland flow and sediment transport. We also combine the numerical model with measurements of debris flow timing to explore relationships between post-wildfire rainfall characteristics, soil infiltration capacity, hillslope erosion, and debris flow initiation at the drainage basin scale. Field data show that an initial rill network developed on the hillslope, and became more efficient over time as the overall rill density decreased. Preliminary model results suggest that this can be achieved when flow driven detachment mechanisms dominate and raindrop-driven detachment is minimized. Results also provide insight into the hydrologic and geomorphic conditions that lead to debris flow initiation within recently burned areas.

  10. Plastic debris in the open ocean

    OpenAIRE

    Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J. Ignacio; Irigoien, Xabier; Úbeda, Bárbara; Hernández-León, Santiago; Palma, Álvaro T.; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L.; Duarte, Carlos M.

    2014-01-01

    There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. Howeve...

  11. Optimized debris stoppers for Z-pinches

    Energy Technology Data Exchange (ETDEWEB)

    Gondarenko, N A; Pereira, N R [Berkeley Research Associates, Springfield, VA (United States)

    1997-12-31

    A pulse power generator discharging through an array of wires or a gas cylinder creates a pulse of useful soft x-rays, which is usually followed by deleterious byproducts such as plasma, hot gases and droplets of metal from evaporated electrodes. Separating the extraneous material from the x-rays is done with a debris shield. Optimization of such shields is discussed. (author). 3 figs., 3 refs.

  12. MOLECULAR GAS IN YOUNG DEBRIS DISKS

    International Nuclear Information System (INIS)

    Moor, A.; Abraham, P.; Kiss, Cs.; Juhasz, A.; Kospal, A.; Pascucci, I.; Apai, D.; Henning, Th.; Csengeri, T.; Grady, C.

    2011-01-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old (∼>8 Myr), gaseous dust disks. From our results, neither primordial origin nor steady secondary production from icy planetesimals can unequivocally explain the presence of CO gas in the disk of HD21997.

  13. Orbital Debris: Past, Present, and Future

    Science.gov (United States)

    Stansbery, Gene; Johnson, Nicholas

    2013-01-01

    In the early days of spaceflight, the gBig Sky h theory was the near universally accepted paradigm for dealing with collisions of orbiting objects. This theory was also used during the early years of the aviation industry. Just as it did in aviation, the gBig Sky h theory breaks down as more and more objects accumulate in the environment. Fortunately, by the late 1970 fs some visionaries in NASA and the US Department of Defense (DoD) realized that trends in the orbital environment would inevitably lead to increased risks to operational spacecraft from collisions with other orbiting objects. The NASA Orbital Debris Program was established at and has been conducted at Johnson Space Center since 1979. At the start of 1979, fewer than 5000 objects were being tracked by the US Space Surveillance Network and very few attempts had been made to sample the environment for smaller sizes. Today, the number of tracked objects has quadrupled. Ground ]based and in situ measurements have statistically sampled the LEO environment over most sizes and mitigation guidelines and requirements are common among most space faring nations. NASA has been a leader, not only in defining the debris environment, but in promoting awareness of the issues in the US and internationally, and in providing leadership in developing policies to address the issue. This paper will discuss in broad terms the evolution of the NASA debris program from its beginnings to its present broad range of debris related research. The paper will discuss in some detail current research topics and will attempt to predict future research trends.

  14. The California Debris Commission: A History

    Science.gov (United States)

    1981-01-01

    the pipe a more freely in the horizontal plane, while vertical elastic packing in the joint instead of two stable instrument to handle. movement was...report of January duplicate and triplicate taxation , and (4) it 1880 painted a dark and sobering picture Following two months of intense and had not the...isolated cases it is possible to impound debris without injury; also, that loca- tions exist in the canons of the different mining streams in the Sierra

  15. Forewarning of Debris flows using Intelligent Geophones

    Science.gov (United States)

    PK, I.; Ramesh, M. V.

    2017-12-01

    Landslides are one of the major catastrophic disasters that cause significant damage to human life and civil structures. Heavy rainfall on landslide prone areas can lead to most dangerous debris flow, where the materials such as mud, sand, soil, rock, water and air will move with greater velocity down the mountain. This sudden slope instability can lead to loss of human life and infrastructure. According to our knowledge, till now no one could identify the minutest factors that lead to initiation of the landslide. In this work, we aim to study the landslide phenomena deeply, using the landslide laboratory set up in our university. This unique mechanical simulator for landslide initiation is equipped with the capability to generate rainfall, seepage, etc., in the laboratory setup. Using this setup, we aim to study several landslide initiation scenarios generated by varying different parameters. The complete setup will be equipped with heterogeneous sensors such as rain gauge, moisture sensor, pore pressure sensor, strain gauges, tiltmeter, inclinometer, extensometer, and geophones. Our work will focus on the signals received from the intelligent geophone system for identifying the underground vibrations during a debris flow. Using the large amount of signals derived from the laboratory set up, we have performed detailed signal processing and data analysis to determine the fore warning signals captured by these heterogeneous sensors. Detailed study of these heterogeneous signals has provided the insights to forewarning the community based on the signals generated during the laboratory tests. In this work we will describe the details of the design, development, methodology, results, inferences and the suggestion for the next step to detect and forewarn the students. The response of intelligent geophone sensors at the time of failure, failure style and subsequent debris flow for heterogeneous soil layers were studied, thus helping in the development of fore warning

  16. Debris flow-induced topographic changes: effects of recurrent debris flow initiation.

    Science.gov (United States)

    Chen, Chien-Yuan; Wang, Qun

    2017-08-12

    Chushui Creek in Shengmu Village, Nantou County, Taiwan, was analyzed for recurrent debris flow using numerical modeling and geographic information system (GIS) spatial analysis. The two-dimensional water flood and mudflow simulation program FLO-2D were used to simulate debris flow induced by rainfall during typhoon Herb in 1996 and Mindulle in 2004. Changes in topographic characteristics after the debris flows were simulated for the initiation of hydrological characteristics, magnitude, and affected area. Changes in topographic characteristics included those in elevation, slope, aspect, stream power index (SPI), topographic wetness index (TWI), and hypsometric curve integral (HI), all of which were analyzed using GIS spatial analysis. The results show that the SPI and peak discharge in the basin increased after a recurrence of debris flow. The TWI was higher in 2003 than in 2004 and indicated higher potential of landslide initiation when the slope of the basin was steeper. The HI revealed that the basin was in its mature stage and was shifting toward the old stage. Numerical simulation demonstrated that the parameters' mean depth, maximum depth, affected area, mean flow rate, maximum flow rate, and peak flow discharge were increased after recurrent debris flow, and peak discharge occurred quickly.

  17. Controlling the Growth of Future LEO Debris Populations with Active Debris Removal

    Science.gov (United States)

    Liou, J.-C.; Johnson, N. L.; Hill, N. M.

    2008-01-01

    Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario, where at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed based on the mass and collision probability of each object as the selection criterion, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.

  18. Mitigation of Debris Flow Damage--­ A Case Study of Debris Flow Damage

    Science.gov (United States)

    Lin, J. C.; Jen, C. H.

    Typhoon Toraji caused more than 30 casualties in Central Taiwan on the 31st July 2001. It was the biggest Typhoon since the Chi-Chi earthquake of 1999 with huge amounts of rainfall. Because of the influence of the earthquake, loose debris falls and flows became major hazards in Central Taiwan. Analysis of rainfall data and sites of slope failure show that damage from these natural hazards were enhanced as a result of the Chi-Chi earthquake. Three main types of hazard occurred in Central Taiwan: land- slides, debris flows and gully erosion. Landslides occurred mainly along hill slopes and banks of channels. Many dams and houses were destroyed by flooding. Debris flows occurred during typhoon periods and re-activated ancient debris depositions. Many new gullies were therefore developed from deposits loosened and shaken by the earthquake. This paper demonstrates the geological/geomorphological background of the hazard area, and reviews methods of damage mitigation in central Taiwan. A good example is Hsi-Tou, which had experienced no gully erosion for more than 40 years. The area experienced much gully erosion as a result of the combined effects of earth- quake and typhoon. Although Typhoon Toraji produced only 30% of the rainfall of Typhoon Herb of 1996, it caused more damage in the Hsi-Tou area. The mitigation of debris flow hazards in Hsi-tou area is discussed in this paper.

  19. Plastic debris in the open ocean

    KAUST Repository

    Cozar, Andres

    2014-06-30

    There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

  20. CIRCUMSTELLAR DEBRIS DISKS: DIAGNOSING THE UNSEEN PERTURBER

    Energy Technology Data Exchange (ETDEWEB)

    Nesvold, Erika R. [Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Rd., Washington, DC 20015 (United States); Naoz, Smadar; Vican, Laura [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Farr, Will M. [School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT (United Kingdom)

    2016-07-20

    The first indication of the presence of a circumstellar debris disk is usually the detection of excess infrared emission from the population of small dust grains orbiting the star. This dust is short-lived, requiring continual replenishment, and indicating that the disk must be excited by an unseen perturber. Previous theoretical studies have demonstrated that an eccentric planet orbiting interior to the disk will stir the larger bodies in the belt and produce dust via interparticle collisions. However, motivated by recent observations, we explore another possible mechanism for heating a debris disk: a stellar-mass perturber orbiting exterior to and inclined to the disk and exciting the disk particles’ eccentricities and inclinations via the Kozai–Lidov mechanism. We explore the consequences of an exterior perturber on the evolution of a debris disk using secular analysis and collisional N -body simulations. We demonstrate that a Kozai–Lidov excited disk can generate a dust disk via collisions and we compare the results of the Kozai–Lidov excited disk with a simulated disk perturbed by an interior eccentric planet. Finally, we propose two observational tests of a dust disk that can distinguish whether the dust was produced by an exterior brown dwarf or stellar companion or an interior eccentric planet.

  1. Plastic debris in the open ocean.

    Science.gov (United States)

    Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J Ignacio; Irigoien, Xabier; Ubeda, Bárbara; Hernández-León, Santiago; Palma, Alvaro T; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L; Duarte, Carlos M

    2014-07-15

    There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

  2. Bremsstrahlung converter debris shields: test and analysis

    International Nuclear Information System (INIS)

    Reedy, E.D. Jr.; Perry, F.C.

    1983-10-01

    Electron beam accelerators are commonly used to create bremsstrahlung x-rays for effects testing. Typically, the incident electron beam strikes a sandwich of three materials: (1) a conversion foil, (2) an electron scavenger, and (3) a debris shield. Several laboratories, including Sandia National Laboratories, are developing bremsstrahlung x-ray sources with much larger test areas (approx. 200 to 500 cm 2 ) than ever used before. Accordingly, the debris shield will be much larger than before and subject to loads which could cause shield failure. To prepare for this eventuality, a series of tests were run on the Naval Surface Weapons Center's Casino electron beam accelerator (approx. 1 MeV electrons, 100 ns FWHM pulse, 45 kJ beam energy). The primary goal of these tests was to measure the stress pulse which loads a debris shield. These measurements were made with carbon gages mounted on the back of the converter sandwich. At an electron beam fluence of about 1 kJ/cm 2 , the measured peak compressive stress was typically in the 1 to 2 kbar range. Measured peak compressive stress scaled in a roughly linear manner with fluence level as the fluence level was increased to 10 kJ/cm 2 . The duration of the compressive pulse was on the order of microseconds. In addition to the stress wave measurements, a limited number of tests were made to investigate the type of damage generated in several potential shield materials

  3. Plastic debris in the open ocean

    Science.gov (United States)

    Cózar, Andrés; Echevarría, Fidel; González-Gordillo, J. Ignacio; Irigoien, Xabier; Úbeda, Bárbara; Hernández-León, Santiago; Palma, Álvaro T.; Navarro, Sandra; García-de-Lomas, Juan; Ruiz, Andrea; Fernández-de-Puelles, María L.; Duarte, Carlos M.

    2014-01-01

    There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean. PMID:24982135

  4. Dynamic transition between fixed- and mobile-bed: mathematical and numerical aspects

    Science.gov (United States)

    Zugliani, Daniel; Pasqualini, Matteo; Rosatti, Giorgio

    2017-04-01

    Free-surface flows with high sediment transport (as debris flow or hyper-concentrated flow) are composed by a mixture of fluid and solid phase, usually water and sediment. When these flows propagate over loose beds, particles constituting the mixture of water and sediments strongly interact with the ones forming the bed, leading to erosion or deposition. However, there are lots of other situations when the mixture flows over rigid bedrocks or over artificially paved transects, so there is no mass exchange between bed and mixture. The two situations are usually referred to as, respectively, mobile- and fixed-bed conditions. From a mathematical point of view, the systems of Partial Differential Equations (PDEs) that describe these flows derive from mass and momentum balance of both phases, but, the two resulting PDEs systems are different. The main difference concerns the concentration: in the mobile-bed condition, the concentration is linked to the local flow conditions by means of a suitable rheological relation, while in the fixed-bed case, the concentration is an unknown of the problem. It is quite common that a free surface flow with high sediment transport, in its path, encounters both conditions. In the recent work of Rosatti & Zugliani 2015, the mathematical and numerical description of the transition between fixed- and mobile-bed was successfully resolved, for the case of low sediment transport phenomena, by the introduction of a suitable erodibility variable and satisfactory results were obtained. The main disadvantage of the approach is related to the erodibility variable, that changes in space, based on bed characteristics, but remains constant in time. However, the nature of the bed can change dynamically as result of deposition over fixed bed or high erosion over mobile bed. With this work, we extend the applicability of the mentioned approach to the more complex PDEs describing the hyper-concentrated flow. Moreover, we introduce a strategy that allows

  5. Treatment technology analysis for mixed waste containers and debris

    International Nuclear Information System (INIS)

    Gehrke, R.J.; Brown, C.H.; Langton, C.A.; Askew, N.M.; Kan, T.; Schwinkendorf, W.E.

    1994-03-01

    A team was assembled to develop technology needs and strategies for treatment of mixed waste debris and empty containers in the Department of Energy (DOE) complex, and to determine the advantages and disadvantages of applying the Debris and Empty Container Rules to these wastes. These rules issued by the Environmental Protection Agency (EPA) apply only to the hazardous component of mixed debris. Hazardous debris that is subjected to regulations under the Atomic Energy Act because of its radioactivity (i.e., mixed debris) is also subject to the debris treatment standards. The issue of treating debris per the Resource Conservation and Recovery Act (RCRA) at the same time or in conjunction with decontamination of the radioactive contamination was also addressed. Resolution of this issue requires policy development by DOE Headquarters of de minimis concentrations for radioactivity and release of material to Subtitle D landfills or into the commercial sector. The task team recommends that, since alternate treatment technologies (for the hazardous component) are Best Demonstrated Available Technology (BDAT): (1) funding should focus on demonstration, testing, and evaluation of BDAT on mixed debris, (2) funding should also consider verification of alternative treatments for the decontamination of radioactive debris, and (3) DOE should establish criteria for the recycle/reuse or disposal of treated and decontaminated mixed debris as municipal waste

  6. Debris flows associated with the 2015 Gorkha Earthquake in Nepal

    Science.gov (United States)

    Dahlquist, M. P.; West, A. J.; Martinez, J.

    2017-12-01

    Debris flows are a primary driver of erosion and a major geologic hazard in many steep landscapes, particularly near the headwaters of rivers, and are generated in large numbers by extreme events. The 2015 Mw 7.8 Gorkha Earthquake triggered 25,000 coseismic landslides in central Nepal. During the ensuing monsoon, sediment delivered to channels by landslides was mobilized in the heavy rains, and new postseismic landslides were triggered in rock weakened by the shaking. These coseismic and postseismic landslide-generated debris flows form a useful dataset for studying the impact and behavior of debris flows on one of the most active landscapes on Earth. Debris flow-dominated channel reaches are generally understood to have a topographic signature recognizable in slope-area plots and distinct from fluvial channels, but in examining debris flows associated with the Gorkha earthquake we find they frequently extend into reaches with geometry typically associated with fluvial systems. We examine a dataset of these debris flows, considering whether they are generated by coseismic or postseismic landslides, whether they are likely to be driving active incision into bedrock, and whether their channels correspond with those typically associated with debris flows. Preliminary analysis of debris flow channels in Nepal suggests there may be systematic differences in the geometry of channels containing debris flows triggered by coseismic versus postseismic landslides, which potentially holds implications for hazard analyses and the mechanics behind the different debris flow types.

  7. Management bedding : vrijloopstal met composterende bedding van houtsnippers

    NARCIS (Netherlands)

    Boer, de H.C.; Wiersma, M.; Galama, P.J.; Szanto, G.L.

    2015-01-01

    In de vrijloopstal liggen de koeien meestal op een organische bedding en scheiden daar mest (feces en urine) uit. Om de bedding voldoende droog en schoon te houden wordt er regelmatig nieuw strooisel aangevoerd en wordt de toplaag bewerkt. Op basis van onderzoek- en praktijkervaringen tot nu toe

  8. Evaluation of materials for retention of sodium and core debris in reactor systems. Annual progress report, September 1977-December 1978

    International Nuclear Information System (INIS)

    Swanson, D.G.; Zehms, E.H.; McClelland, J.D.; Meyer, R.A.; van Paassen, H.L.L.

    1978-12-01

    This report considers some of the consequences of a hypothetical core disruptive accident in a nuclear reactor. The interactions expected between molten core debris, liquid sodium, and materials that might be employed in an ex-vessel sacrificial-bed or in the reactor building are discussed. Experimental work performed for NRC by Sandia Laboratories and Hanford Engineering Development Laboratory on the interactions between liquid sodium and basalt concrete is reviewed. Studies of molten steel interactions with concrete at Sandia Laboratories and molten UO 2 interactions with concrete at The Aerospace Corporation are also discussed. The potential of MgO for use in core containment is discussed and refractory materials other than MgO are reviewed. Finally, results from earlier experiments with molten core debris and various materials performed at The Aerospace Corporation are presented

  9. Summary of Disposable Debris Shields (DDS) Analysis for Development of Solid Debris Collection at NIF

    International Nuclear Information System (INIS)

    Shaughnessy, D.A.; Moody, K.J.; Grant, P.M.; Lewis, L.A.; Hutcheon, I.D.; Lindvall, R.; Gostic, J.M.

    2011-01-01

    Collection of solid debris from the National Ignition Facility (NIF) is being developed both as a diagnostic tool and as a means for measuring nuclear reaction cross sections relevant to the Stockpile Stewardship Program and nuclear astrophysics. The concept is straightforward; following a NIF shot, the debris that is produced as a result of the capsule and hohlraum explosion would be collected and subsequently extracted from the chamber. The number of nuclear activations that occurred in the capsule would then be measured through a combination of radiation detection and radiochemical processing followed by mass spectrometry. Development of the catcher is challenging due to the complex environment of the NIF target chamber. The collector surface is first exposed to a large photon flux, followed by the debris wind that is produced. The material used in the catcher must be mechanically strong in order to withstand the large amount of energy it is exposed to, as well as be chemically compatible with the form and composition of the debris. In addition, the location of the catcher is equally important. If it is positioned too close to the center of the target chamber, it will be significantly ablated, which could interfere with the ability of the debris to reach the surface and stick. If it is too far away, the fraction of the debris cloud collected will be too small to result in a statistically significant measurement. Material, geometric configuration, and location must all be tested in order to design the optimal debris collection system for NIF. One of the first ideas regarding solid debris collection at NIF was to use the disposable debris shields (DDS), which are fielded over the final optics assemblies (FOA) 7 m away from the center of the target chamber. The DDS are meant to be replaced after a certain number of shots, and if the shields could be subsequently analyzed after removal, it would serve as a mechanism for fielding a relatively large collection area

  10. New advances for modelling the debris avalanches

    Science.gov (United States)

    Cuomo, Sabatino; Cascini, Leonardo; Pastor, Manuel; Castorino, Giuseppe Claudio

    2013-04-01

    Flow-like landslides are a major global hazard and they occur worldwide causing a large number of casualties, significant structural damages to property and infrastructures as well as economic losses. When involving open slopes, these landslides often occur in triangular source areas where initial slides turn into avalanches through further failures and/or eventual soil entrainment. This paper deals with the numerical modelling of the propagation stage of debris avalanches which provides information such as the propagation pattern of the mobilized material, its velocity, thickness and run-out distance. In the paper, a "depth integrated" model is used which allows: i) adequately taking into account the irregular topography of real slopes which greatly affect the propagation stage and ii) using a less time consuming model than fully 3D approaches. The used model is named "GeoFlow_SPH" and it was formerly applied to theoretical, experimental and real case histories (Pastor et al., 2009; Cascini et al., 2012). In this work the behavior of debris avalanches is analyzed with special emphasis on the apical angle, one of the main features of this type of landslide, in relation to soil rheology, hillslope geometry and features of triggering area. Furthermore, the role of erosion has been investigated with reference to the uppermost parts of open slopes with a different steepness. These analyses are firstly carried out for simplified benchmark slopes, using both water-like materials (with no shear strength) and debris type materials. Then, three important case studies of Campania region (Cervinara, Nocera Inferiore e Sarno) are analyzed where debris avalanches involved pyroclastic soils originated from the eruptive products of Vesusius volcano. The results achieved for both benchmark slopes and real case histories outline the key role played by the erosion on the whole propagation stage of debris avalanches. The results are particularly satisfactory since they indicate the

  11. A probabilistic approach for debris impact risk with numerical simulations of debris behaviors

    International Nuclear Information System (INIS)

    Kihara, Naoto; Matsuyama, Masafumi; Fujii, Naoki

    2013-01-01

    We propose a probabilistic approach for evaluating the impact risk of tsunami debris through Monte Carlo simulations with a combined system comprising a depth-averaged two-dimensional shallow water model and a discrete element model customized to simulate the motions of floating objects such as vessels. In the proposed method, first, probabilistic tsunami hazard analysis is carried out, and the exceedance probability of tsunami height and numerous tsunami time series for various hazard levels on the offshore side of a target site are estimated. Second, a characteristic tsunami time series for each hazard level is created by cluster analysis. Third, using the Monte Carlo simulation model the debris impact probability with the buildings of interest and the exceedance probability of debris impact speed are evaluated. (author)

  12. Modeling collisions in circumstellar debris disks

    Science.gov (United States)

    Nesvold, Erika

    2015-10-01

    Observations of resolved debris disks show a spectacular variety of features and asymmetries, including inner cavities and gaps, inclined secondary disks or warps, and eccentric, sharp-edged rings. Embedded exoplanets could create many of these features via gravitational perturbations, which sculpt the disk directly and by generating planetesimal collisions. In this thesis, I present the Superparticle Model/Algorithm for Collisions in Kuiper belts and debris disks (SMACK), a new method for simultaneously modeling, in 3-D, the collisional and dynamical evolution of planetesimals in a debris disk with planets. SMACK can simulate azimuthal asymmetries and how these asymmetries evolve over time. I show that SMACK is stable to numerical viscosity and numerical heating over 107 yr, and that it can reproduce analytic models of disk evolution. As an example of the algorithm's capabilities, I use SMACK to model the evolution of a debris ring containing a planet on an eccentric orbit and demonstrate that differential precession creates a spiral structure as the ring evolves, but collisions subsequently break up the spiral, leaving a narrower eccentric ring. To demonstrate SMACK's utility in studying debris disk physics, I apply SMACK to simulate a planet on a circular orbit near a ring of planetesimals that are experiencing destructive collisions. Previous simulations of a planet opening a gap in a collisionless debris disk have found that the width of the gap scales as the planet mass to the 2/7th power (alpha = 2/7). I find that gap sizes in a collisional disk still obey a power law scaling with planet mass, but that the index alpha of the power law depends on the age of the system t relative to the collisional timescale t coll of the disk by alpha = 0.32(t/ tcoll)-0.04, with inferred planet masses up to five times smaller than those predicted by the classical gap law. The increased gap sizes likely stem from the interaction between collisions and the mean motion

  13. Azimuthal asymmetries in the debris disk around HD 61005. A massive collision of planetesimals?

    Science.gov (United States)

    Olofsson, J.; Samland, M.; Avenhaus, H.; Caceres, C.; Henning, Th.; Moór, A.; Milli, J.; Canovas, H.; Quanz, S. P.; Schreiber, M. R.; Augereau, J.-C.; Bayo, A.; Bazzon, A.; Beuzit, J.-L.; Boccaletti, A.; Buenzli, E.; Casassus, S.; Chauvin, G.; Dominik, C.; Desidera, S.; Feldt, M.; Gratton, R.; Janson, M.; Lagrange, A.-M.; Langlois, M.; Lannier, J.; Maire, A.-L.; Mesa, D.; Pinte, C.; Rouan, D.; Salter, G.; Thalmann, C.; Vigan, A.

    2016-06-01

    Context. Debris disks offer valuable insights into the latest stages of circumstellar disk evolution, and can possibly help us to trace the outcomes of planetary formation processes. In the age range 10 to 100 Myr, most of the gas is expected to have been removed from the system, giant planets (if any) must have already been formed, and the formation of terrestrial planets may be on-going. Pluto-sized planetesimals, and their debris released in a collisional cascade, are under their mutual gravitational influence, which may result into non-axisymmetric structures in the debris disk. Aims: High angular resolution observations are required to investigate these effects and constrain the dynamical evolution of debris disks. Furthermore, multi-wavelength observations can provide information about the dust dynamics by probing different grain sizes. Methods: Here we present new VLT/SPHERE and ALMA observations of the debris disk around the 40 Myr-old solar-type star HD 61005. We resolve the disk at unprecedented resolution both in the near-infrared (in scattered and polarized light) and at millimeter wavelengths. We perform a detailed modeling of these observations, including the spectral energy distribution. Results: Thanks to the new observations, we propose a solution for both the radial and azimuthal distribution of the dust grains in the debris disk. We find that the disk has a moderate eccentricity (e ~ 0.1) and that the dust density is two times larger at the pericenter compared to the apocenter. Conclusions: With no giant planets detected in our observations, we investigate alternative explanations besides planet-disk interactions to interpret the inferred disk morphology. We postulate that the morphology of the disk could be the consequence of a massive collision between ~1000 km-sized bodies at ~61 au. If this interpretation holds, it would put stringent constraints on the formation of massive planetesimals at large distances from the star. Based on observations

  14. Development of Large Scale Bed Forms in the Sea –2DH Numerical Modeling

    DEFF Research Database (Denmark)

    Margalit, Jonatan; Fuhrman, David R.

    Large repetitive patterns on the sea bed are commonly observed in sandy areas. The formation of the bed forms have been studied extensively in literature using linear stability analyses, commonly conducted analytically and with simplifications in the governing equations. This work presents...... a shallow water equation model that is used to numerically simulate the morphodynamics of the water-bed system. The model includes separate formulations for bed load and suspended load, featuring bed load correction due to a sloping bed and modelled helical flow effects. Horizontal gradients are computed...... with spectral accuracy, which proves highly efficient for the analysis. Numerical linear stability analysis is used to identify the likely emergence of dominant finite sized bed forms, as a function of governing parameters. These are then used for interpretation of the results of a long time morphological...

  15. Facies characteristics of the basal part of the Talchir Formation ...

    Indian Academy of Sciences (India)

    Keywords. Gondwana sedimentation; Talchir Formation; Talchir Basin; debris flow; entrained turbidity current. ... in the Tikra river in the northern part of the basin. (figure 1). ... The arrow shows load structure at the clay-silt interface (the scale is.

  16. Carbon Bed Mercury Emissions Control For Mixed Waste Treatment

    International Nuclear Information System (INIS)

    Soelberg, Nick; Enneking, Joe

    2010-01-01

    Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (both radioactive and hazardous according to the Resource Conservation and Recovery Act) wastes. Depending on regulatory requirements, the mercury in the off-gas must be controlled with sometimes very high efficiencies. Compliance to the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards can require off-gas mercury removal efficiencies up to 99.999% for thermally treating some mixed waste streams. Several test programs have demonstrated this level of off-gas mercury control using fixed beds of granular sulfur-impregnated activated carbon. Other results of these tests include: (a) The depth of the mercury control mass transfer zone was less than 15-30 cm for the operating conditions of these tests, (b) MERSORB(reg s ign) carbon can sorb Hg up to 19 wt% of the carbon mass, and (c) the spent carbon retained almost all (98-99.99%) of the Hg; but when even a small fraction of the total Hg dissolves, the spent carbon can fail the TCLP test when the spent carbon contains high Hg concentrations. Localized areas in a carbon bed that become heated through heat of adsorption, to temperatures where oxidation occurs, are referred to as 'bed hot spots.' Carbon bed hot spots must be avoided in processes that treat radioactive and mixed waste. Key to carbon bed hot spot mitigation are (a) designing for sufficient gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) monitoring and control of inlet gas flowrate, temperature, and composition, (c) monitoring and control of in-bed and bed outlet gas temperatures, and (d) most important, monitoring of bed outlet CO concentrations. An increase of CO levels in the off-gas downstream of the carbon bed to levels about 50-100 ppm higher than the inlet CO concentration indicate CO formation in the bed, caused by carbon bed

  17. Effectiveness of Bed Bug Pesticides

    Science.gov (United States)

    Before EPA allows a bed bug claim on a label, the product must be supported by data showing it will kill bed bugs when applied according to the label. Also consider factors such as extent of infestation, site preparation, and insect life stages.

  18. Stratigraphic reconstruction of two debris avalanche deposits at Colima Volcano (Mexico): Insights into pre-failure conditions and climate influence

    Science.gov (United States)

    Roverato, M.; Capra, L.; Sulpizio, R.; Norini, G.

    2011-10-01

    conditions at the time of the collapse. The presence of extensive water at the onset of deglaciation modified the mobility of the debris avalanche, and led to the formation of a thick sequence of debris flows. The possibility that such a combination of events can occur, and that their probability is likely to increase during the rainy season, should be taken into consideration when evaluating hazards associated with future collapses at Colima volcano.

  19. A mineralogical and granulometric study of Cayambe volcano debris avalanche deposit

    Science.gov (United States)

    Detienne, M.; Delmelle, P.; Guevara, A.; Samaniego, P.; Bustillos, J.; Sonnet, P.; Opfergelt, S.

    2013-12-01

    Volcano flank/sector collapse represents one of the most catastrophic volcanic hazards. Various volcanic and non-volcanic processes are known to decrease the stability of a volcanic cone, eventually precipitating its gravitational failure. Among them, hydrothermal alteration of volcanic rocks leading to clay mineral formation is recognized as having a large negative impact on rock strength properties. Furthermore, the presence of hydrothermal clays in the collapsing mass influences the behavior of the associated volcanic debris avalanche. In particular, clay-containing debris avalanches seem to travel farther and spread more widely than avalanches of similar volume but which do not incorporate hydrothermally-altered materials. However, the relationship between hydrothermal alteration, flank collapse and debris avalanche behavior is not well understood. The objective of this study is to better determine the volume and composition of hydrothermal clay minerals in the poorly characterized debris avalanche deposit (DAD) of Cayambe composite volcano, located in a densely populated area ~70 km northeast of Quito, Ecuador. Cayambe DAD originated from a sector collapse, which occurred less than 200 ka ago. The DAD is 10-20 m thick and has an estimated total volume of ~0.85 Km3. The H/L ratio (where H is the vertical drop and L is the travel distance of the avalanche) for Cayambe DAD is ~0.095, suggesting a high mobility. In the medial-distal zone, at 9-20 km from its source, the DAD consists of an unstratified and unsorted matrix supporting millimetric to metric clasts. It has a matrix facies (i.e. rich in particles DAD behaved as a cohesive debris flow. Analysis of 13 matrix samples reveals a large variability in particle size distribution. This may reflect poor mixing of the collapsed material during transport. The clay fraction content in the matrix ranges from 15 to 30 wt.%, and does not show a relationship with the sample position in the DAD. Mineralogical

  20. DEBRIS DISKS IN THE SCORPIUS–CENTAURUS OB ASSOCIATION RESOLVED BY ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Lieman-Sifry, Jesse; Hughes, A. Meredith; Flaherty, Kevin M. [Department of Astronomy, Van Vleck Observatory, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States); Carpenter, John M. [Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Gorti, Uma [SETI Institute, Mountain View, CA (United States); Hales, Antonio [Atacama Large Millimeter/Submillimeter Array, Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura 763-0355, Santiago (Chile)

    2016-09-01

    We present a CO(2-1) and 1240 μ m continuum survey of 23 debris disks with spectral types B9-G1, observed at an angular resolution of 0.″5–1″ with the Atacama Large Millimeter/Submillimeter Array (ALMA). The sample was selected for large infrared excess and age ∼10 Myr, to characterize the prevalence of molecular gas emission in young debris disks. We identify three CO-rich debris disks, plus two additional tentative (3 σ) CO detections. Twenty disks were detected in the continuum at the >3 σ level. For the 12 disks in the sample that are spatially resolved by our observations, we perform an independent analysis of the interferometric continuum visibilities to constrain the basic dust disk geometry, as well as a simultaneous analysis of the visibilities and broadband spectral energy distribution to constrain the characteristic grain size and disk mass. The gas-rich debris disks exhibit preferentially larger outer radii in their dust disks, and a higher prevalence of characteristic grain sizes smaller than the blowout size. The gas-rich disks do not exhibit preferentially larger dust masses, contrary to expectations for a scenario in which a higher cometary destruction rate would be expected to result in a larger mass of both CO and dust. The three debris disks in our sample with strong CO detections are all around A stars: the conditions in disks around intermediate-mass stars appear to be the most conducive to the survival or formation of CO.

  1. Modeling the Long-Term Evolution of Supraglacial Ice Cliffs on Himalayan Debris-Covered Glaciers

    Science.gov (United States)

    Buri, P.; Miles, E. S.; Steiner, J. F.; Ragettli, S.; Pellicciotti, F.

    2016-12-01

    Supraglacial ice cliffs are present on debris-covered glaciers worldwide and provide the only direct atmosphere-ice interface over the lower sections of these glaciers. Low albedo and high longwave emissions from surrounding debris cause very high melt rates, accounting for a significant portion of total glacier mass loss. As a result, ice cliffs affect glacier downwasting and mass balance. Additionally, and in contrast to the debris-covered ice, high melt at cliffs turns them into dynamic features, directly affecting glacier surface evolution. While conceptual ideas about the formation, evolution and collapse of ice cliffs exist, their life cycles have never been thoroughly documented. Based on observations obtained from high-resolution aerial and terrestrial images analyzed with Structure-from-Motion and with data from automatic weather stations on two glaciers in the Nepalese Himalaya, we simulate the evolution of selected ice cliffs over several seasons using a new physically-based model of cliff backwasting. The 3D model calculates the energy-balance at the cliff scale and includes the cliff interaction with supraglacial ponds and reburial by debris. We consider cliffs of different shape, orientation and slope, and we show that backwasting leads to a variety of evolution typologies, with cliffs that maintain a constant, self-similar geometry, cliffs that grow laterally and cliffs that disappear through slope shallowing and debris melt-out. Most cliffs persist over several seasons. The presence of a pond appears to be the key control for cliffs to survive, while east and west facing cliffs grow because of higher radiation receipts. We use the model to test the hypothesis that south-facing cliffs do not survive. We show that most south-facing cliffs demise after one melt season on both glaciers, because of high input of solar radiation exceeding the longwave radiation receipt. For north facing features, the longwave radiation receipts at lower cliff sections

  2. Study of Pressure Drop in Fixed Bed Reactor Using a Computational Fluid Dynamics (CFD Code

    Directory of Open Access Journals (Sweden)

    Soroush Ahmadi

    2018-04-01

    Full Text Available Pressure drops of water and critical steam flowing in the fixed bed of mono-sized spheres are studied using SolidWorks 2017 Flow Simulation CFD code. The effects of the type of bed formation, flow velocity, density, and pebble size are evaluated. A new equation is concluded from the data, which is able to estimate pressure drop of a packed bed for high particle Reynolds number, from 15,000 to 1,000,000.

  3. Flaser and wavy bedding in ephemeral streams: a modern and an ancient example

    Science.gov (United States)

    Martin, A. J.

    2000-10-01

    Flaser and wavy bedding are sedimentary structures characterized by alternating rippled sand and mud layers. These structures often are considered to form mostly in tidally influenced environments; published examples from fluvial environments are rare. Flaser and wavy bedding were found in two ephemeral stream deposits: the Jurassic Kayenta Formation and the modern wash in Seven Mile Canyon, both located in southeastern Utah, USA. These examples demonstrate that flaser bedding can form and be preserved in ephemeral streams.

  4. Data Acquisition, Management, and Analysis in Support of the Audiology and Hearing Conservation and the Orbital Debris Program Office

    Science.gov (United States)

    Dicken, Todd

    2012-01-01

    My internship at Johnson Space Center, Houston TX comprised of working simultaneously in the Space Life Science Directorate (Clinical Services Branch, SD3) in Audiology and Hearing Conservation and in the Astromaterials Research and Exploration Sciences Directorate in the Orbital Debris Program Office (KX). The purpose of the project done to support the Audiology and Hearing Conservation Clinic (AuHCon) is to organize and analyze auditory test data that has been obtained from tests conducted onboard the International Space Station (ISS) and in Johnson Space Center's clinic. Astronauts undergo a special type of auditory test called an On-Orbit Hearing Assessment (OOHA), which monitors hearing function while crewmembers are exposed to noise and microgravity during long-duration spaceflight. Data needed to be formatted to assist the Audiologist in studying, analyzing and reporting OOHA results from all ISS missions, with comparison to conventional preflight and post-flight audiometric test results of crewmembers. Orbital debris is the #1 threat to manned spacecraft; therefore NASA is investing in different measurement techniques to acquire information on orbital debris. These measurements are taken with telescopes in different parts of the world to acquire brightness variations over time, from which size, rotation rates and material information can be determined for orbital debris. Currently many assumptions are taken to resolve size and material from observed brightness, therefore a laboratory (Optical Measurement Center) is used to simulate the space environment and acquire information of known targets suited to best model the orbital debris population. In the Orbital Debris Program Office (ODPO) telescopic data were acquired and analyzed to better assess the orbital debris population.

  5. Reference repository design concept for bedded salt

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, D.W.; Martin, R.W.

    1980-10-08

    A reference design concept is presented for the subsurface portions of a nuclear waste repository in bedded salt. General geologic, geotechnical, hydrologic and geochemical data as well as descriptions of the physical systems are provided for use on generic analyses of the pre- and post-sealing performance of repositories in this geologic medium. The geology of bedded salt deposits and the regional and repository horizon stratigraphy are discussed. Structural features of salt beds including discontinuities and dissolution features are presented and their effect on repository performance is discussed. Seismic hazards and the potential effects of earthquakes on underground repositories are presented. The effect on structural stability and worker safety during construction from hydrocarbon and inorganic gases is described. Geohydrologic considerations including regional hydrology, repository scale hydrology and several hydrological failure modes are presented in detail as well as the hydrological considerations that effect repository design. Operational phase performance is discussed with respect to operations, ventilation system, shaft conveyances, waste handling and retrieval systems and receival rates of nuclear waste. Performance analysis of the post sealing period of a nuclear repository is discussed, and parameters to be used in such an analysis are presented along with regulatory constraints. Some judgements are made regarding hydrologic failure scenarios. Finally, the design and licensing process, consistent with the current licensing procedure is described in a format that can be easily understood.

  6. Reference repository design concept for bedded salt

    International Nuclear Information System (INIS)

    Carpenter, D.W.; Martin, R.W.

    1980-01-01

    A reference design concept is presented for the subsurface portions of a nuclear waste repository in bedded salt. General geologic, geotechnical, hydrologic and geochemical data as well as descriptions of the physical systems are provided for use on generic analyses of the pre- and post-sealing performance of repositories in this geologic medium. The geology of bedded salt deposits and the regional and repository horizon stratigraphy are discussed. Structural features of salt beds including discontinuities and dissolution features are presented and their effect on repository performance is discussed. Seismic hazards and the potential effects of earthquakes on underground repositories are presented. The effect on structural stability and worker safety during construction from hydrocarbon and inorganic gases is described. Geohydrologic considerations including regional hydrology, repository scale hydrology and several hydrological failure modes are presented in detail as well as the hydrological considerations that effect repository design. Operational phase performance is discussed with respect to operations, ventilation system, shaft conveyances, waste handling and retrieval systems and receival rates of nuclear waste. Performance analysis of the post sealing period of a nuclear repository is discussed, and parameters to be used in such an analysis are presented along with regulatory constraints. Some judgements are made regarding hydrologic failure scenarios. Finally, the design and licensing process, consistent with the current licensing procedure is described in a format that can be easily understood

  7. Protecting Spacecraft Fragments from Exposure to Small Debris

    OpenAIRE

    V. V. Zelentsov

    2015-01-01

    Since the launch of the first artificial Earth satellite a large amount of space debris has been accumulated in near-earth space. This debris comprises the exhausted spacecrafts, final stages of rocket-carriers and boosters, technological space junk, consisting of the structure elements, which are separated when deploying the solar arrays, antennas etc., as well as when undocking a booster and a spacecraft. All the debris is divided into observable one of over 100 mm in size and unobservable ...

  8. Anthropogenic effect on avalanche and debris flow activity

    OpenAIRE

    S. A. Sokratov; Yu. G. Seliverstov; A. L. Shnyparkov; K. P. Koltermann

    2013-01-01

    The paper presents examples of the change in snow avalanches and debris flows activity due to the anthropogenic pressure on vegetation and relief. The changes in dynamical characteristics of selected snow avalanches and debris flows due to the anthropogenic activity are quantified. The conclusion is made that the anthropogenic effects on the snow avalanches and debris flows activity are more pronounced than the possible effects of the climate change. The necessity is expressed on the unavoida...

  9. Incidence of Debris Discs Around FGK Stars in the Solar Neighbourhood

    Science.gov (United States)

    Montesinos, B.; Eiroa, C.; Krivov, A. V.; Marshall, J. P.; Pilbratt, G. L.; Liseau, R.; Mora, A.; Maldonado, J.; Wolf, S.; Ertel, S.; hide

    2016-01-01

    Context. Debris discs are a consequence of the planet formation process and constitute the fingerprints of planetesimal systems. Their counterparts in the solar system are the asteroid and Edgeworth-Kuiper belts. Aims. The aim of this paper is to provide robust numbers for the incidence of debris discs around FGK stars in the solar neighborhood. Methods. The full sample of 177 FGK stars with d approx. less than 20 pc proposed for the DUst around NEarby Stars (DUNES) survey is presented. Herschel/PACS observations at 100 and 160 micrometers were obtained, and were complemented in some cases with data at 70 micrometers and at 250, 350, and 500 micrometer SPIRE photometry. The 123 objects observed by the DUNES collaboration were presented in a previous paper. The remaining 54 stars, shared with the Disc Emission via a Bias-free Reconnaissance in IR and Sub-mm (DEBRIS) consortium and observed by them, and the combined full sample are studied in this paper. The incidence of debris discs per spectral type is analyzed and put into context together with other parameters of the sample, like metallicity, rotation and activity, and age. Results. The subsample of 105 stars with d approx. less than 15 pc containing 23 F, 33 G, and 49 K stars is complete for F stars, almost complete for G stars, and contains a substantial number of K stars from which we draw solid conclusions on objects of this spectral type. The incidence rates of debris discs per spectral type are 0.26(+0.21/-0.14) (6 objects with excesses out of 23 F stars), 0.21(+0.17/-0.11) (7 out of 33 G stars), and 0.20(+0.14/-0.09) (10 out of 49 K stars); the fraction for all three spectral types together is 0.22(+0.08/-0.07) (23 out of 105 stars).The uncertainties correspond to a 95 confidence level. The medians of the upper limits of L(sub dust)/L(sub *) for each spectral type are 7.8 x 10(exp -7) (F), 1.4 x 10(exp -6) (G), and 2.2 x 10(exp -6) (K); the lowest values are around 4.0 x 10(exp -7). The incidence of debris

  10. Development and Evaluation of a Wide-Bed Former for Vegetable Cultivation in Controlled Tractor Traffic

    Science.gov (United States)

    Dixit, Anoop; Khurana, Rohinish; Verma, Aseem; Singh, Arshdeep; Manes, G. S.

    2018-05-01

    India is the second largest producer of vegetables in the world. For vegetable cultivation, a good seed bed preparation is an important task which involves 6-10 different operations. To tackle the issue of multiple operations, a prototype of tractor operated wide bed former was developed and evaluated. The machine comprises of a rotary tiller and a bed forming setup. It forms bed of 1000 mm top width which is suitable as per the track width of an average sized tractor in India. The height of the beds formed is 130 mm whereas the top and bottom width of channel formed on both sides of the bed is 330 and 40 mm respectively at soil moisture content of 12.5-16% (db). The forward speed of 2.75 km/h was observed to be suitable for proper bed formation. The average fuel consumption of the machine was 5.9 l/h. The average bulk density of soil before and after the bed formation was 1.46 and 1.63 g/cc respectively. Field capacity of the machine was found to be 0.31 ha/h. The machine resulted in 93.8% labour saving and 80.4% saving in cost of bed preparation as compared to conventional farmer practice. Overall performance of wide-bed former was found to be satisfactory.

  11. Molten core debris-sodium interactions: M-Series experiments

    International Nuclear Information System (INIS)

    Sowa, E.S.; Gabor, J.D.; Pavlik, J.R.; Cassulo, J.C.; Cook, C.J.; Baker, L. Jr.

    1979-01-01

    Five new kilogram-scale experiments have been carried out. Four of the experiments simulated the situation where molten core debris flows from a breached reactor vessel into a dry reactor cavity and is followed by a flow of sodium (Ex-vessel case) and one experiment simulated the flow of core debris into an existing pool of sodium (In-vessel case). The core debris was closely simulated by a thermite reaction which produced a molten mixture of UO 2 , ZrO 2 , and stainless steel. There was efficient fragmentation of the debris in all experiments with no explosive interactions observed

  12. Understanding sources, sinks, and transport of marine debris

    Science.gov (United States)

    Law, Kara Lavender; Maximenko, Nikolai

    2011-07-01

    Fifth International Marine Debris Conference: Hydrodynamics of Marine Debris; Honolulu, Hawaii, 20 March 2011; Ocean pollution in the form of marine debris, especially plastic debris, has received increasing public and media attention in recent years through striking but frequently inaccurate descriptions of “garbage patches.” Marine debris is composed of all manufactured materials, including glass, metal, paper, fibers, and plastic, that have been deliberately dumped or that accidentally entered the marine environment. Marine debris is most visible on beaches, but it has been observed in all oceans and in such remote locations as on the deep seabed and floating in the middle of subtropical ocean gyres. While many initiatives have been developed to solve this pollution problem through prevention and cleanup efforts, there is relatively little scientific information available to assess the current status of the problem or to provide metrics to gauge the success of remediation measures. With this in mind, a full-day workshop entitled “Hydrodynamics of Marine Debris” was convened at the Fifth International Marine Debris Conference in Hawaii, bringing together observational scientists and oceanographic modelers to outline the steps necessary to quantify the major sources and sinks of marine debris and the pathways between them. The ultimate goal in integrating the two approaches of study is to quantify the basinscale and global inventory of marine debris by closing the associated mass budgets.

  13. Classification of debris flow phenomena in the Faroe Islands

    DEFF Research Database (Denmark)

    Dahl, Mads-Peter Jakob; E. Mortensen, Lis; Jensen, Niels H.

    2012-01-01

    Landslides and debris flow phenomena in particular constitute a threat to human activities in the Faroe Islands. As a contribution to ongoing landslide risk management research, this paper proposes a classification scheme for debris flow phenomena in the Faroe Islands. The scheme, produced through...... a multidisciplinary study involving geomorphological fieldwork and qualitative collection of indigenous landslide knowledge, presents physical characteristics to classify debris flow phenomena into groups named with Faroese terms. The following landslide definitions are proposed. Brekku-skriðulop (English translation...... with international landslide classification systems, significantly increases the knowledge of debris flow phenomena and promotes a consistent terminology of these within the Faroe Islands....

  14. Influence of Rack Design and Disease Prevalence on Detection of Rodent Pathogens in Exhaust Debris Samples from Individually Ventilated Caging Systems.

    Science.gov (United States)

    Bauer, Beth A; Besch-Williford, Cynthia; Livingston, Robert S; Crim, Marcus J; Riley, Lela K; Myles, Matthew H

    2016-11-01

    Sampling of bedding debris within the exhaust systems of ventilated racks may be a mechanism for detecting murine pathogens in colony animals. This study examined the effectiveness of detecting pathogens by PCR analysis of exhaust debris samples collected from ventilated racks of 2 different rack designs, one with unfiltered air flow from within the cage to the air-exhaust pathway, and the other had a filter between the cage and the air-exhaust pathway. For 12 wk, racks were populated with either 1 or 5 cages of mice (3 mice per cage) infected with one of the following pathogens: mouse norovirus (MNV), mouse parvovirus (MPV), mouse hepatitis virus (MHV), Helicobacter spp., Pasteurella pneumotropica, pinworms, Entamoeba muris, Tritrichomonas muris, and fur mites. Pathogen shedding by infected mice was monitored throughout the study. In the filter-containing rack, PCR testing of exhaust plenums yielded negative results for all pathogens at all time points of the study. In the rack with open air flow, pathogens detected by PCR analysis of exhaust debris included MHV, Helicobacter spp., P. pneumotropica, pinworms, enteric protozoa, and fur mites; these pathogens were detected in racks housing either 1 or 5 cages of infected mice. Neither MPV nor MNV was detected in exhaust debris, even though prolonged viral shedding was confirmed. These results demonstrate that testing rack exhaust debris from racks with unfiltered air flow detected MHV, enteric bacteria and parasites, and fur mites. However, this method failed to reliably detect MNV or MPV infection of colony animals.

  15. Major salt beds of the Palo Duro and Dalhart Basins, Texas

    International Nuclear Information System (INIS)

    1983-12-01

    Major salt beds are defined as salt intervals at least 75 feet thick that contain no interbeds greater than 10 feet thick and include no more than 15 percent non-salt interbeds. Maps based on the interpretation of geophysical logs from hundreds of oil and gas exploration wells reveal seven major salt beds in the Palo Duro Basin and one major salt bed in the Dalhart Basin. The most extensive major salt beds are in the central and northern Palo Duro Basin, in the Upper San Andres Formation and the Lower San Andres Formation Units 4 and 5. Of these, the major salt bed within the Lower San Andres Formation Unit 4 is the most widespread and generally the thickest. 7 references, 15 figures, 2 tables

  16. Marine debris removal: one year of effort by the Georgia Sea Turtle-Center-Marine Debris Initiative.

    Science.gov (United States)

    Martin, Jeannie Miller

    2013-09-15

    Once in the marine environment, debris poses a significant threat to marine life that can be prevented through the help of citizen science. Marine debris is any manufactured item that enters the ocean regardless of source, commonly plastics, metal, wood, glass, foam, cloth, or rubber. Citizen science is an effective way to engage volunteers in conservation initiatives and provide education and skill development. The Georgia Sea Turtle Center Marine Debris Initiative (GSTC-MDI) is a grant funded program developed to engage citizens in the removal of marine debris from the beaches of Jekyll Island, GA, USA and the surrounding areas. During the first year of effort, more than 200 volunteers donated over 460 h of service to the removal of marine debris. Of the debris removed, approximately 89% were plastics, with a significant portion being cigarette materials. Given the successful first year, the GSTC-MDI was funded again for a second year. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. The Population of Optically Faint GEO Debris

    Science.gov (United States)

    Seitzer, Patrick; Barker, Ed; Buckalew, Brent; Burkhardt, Andrew; Cowardin, Heather; Frith, James; Gomez, Juan; Kaleida, Catherine; Lederer, Susan M.; Lee, Chris H.

    2016-01-01

    The 6.5-m Magellan telescope 'Walter Baade' at the Las Campanas Observatory in Chile has been used for spot surveys of the GEO orbital regime to study the population of optically faint GEO debris. The goal is to estimate the size of the population of GEO debris at sizes much smaller than can be studied with 1-meter class telescopes. Despite the small size of the field of view of the Magellan instrument (diameter 0.5-degree), a significant population of objects fainter than R = 19th magnitude have been found with angular rates consistent with circular orbits at GEO. We compare the size of this population with the numbers of GEO objects found at brighter magnitudes by smaller telescopes. The observed detections have a wide range in characteristics starting with those appearing as short uniform streaks. But there are a substantial number of detections with variations in brightness, flashers, during the 5-second exposure. The duration of each of these flashes can be extremely brief: sometimes less than half a second. This is characteristic of a rapidly tumbling object with a quite variable projected size times albedo. If the albedo is of the order of 0.2, then the largest projected size of these objects is around 10-cm. The data in this paper was collected over the last several years using Magellan's IMACS camera in f/2 mode. The analysis shows the brightness bins for the observed GEO population as well as the periodicity of the flashers. All objects presented are correlated with the catalog: the focus of the paper will be on the uncorrelated, optically faint, objects. The goal of this project is to better characterize the faint debris population in GEO that access to a 6.5-m optical telescope in a superb site can provide.

  18. Protecting Your Home from Bed Bugs

    Science.gov (United States)

    ... your home: Inspect the luggage rack in your hotel room for bed bugs. Check secondhand furniture, beds, ... with Bed Bug Problems Discover. Accessibility EPA Administrator Budget & Performance Contracting Grants January 19, 2017 Web Snapshot ...

  19. Improvement and evaluation of debris coolability analysis module in severe accident analysis code SAMPSON using LIVE experiment

    International Nuclear Information System (INIS)

    Wei, Hongyang; Erkan, Nejdet; Okamoto, Koji; Gaus-Liu, Xiaoyang; Miassoedov, Alexei

    2017-01-01

    Highlights: • Debris coolability analysis module in SAMPSON is validated. • Model for heat transfer between melt pool and pressure vessel wall is modified. • Modified debris coolability analysis module is found to give reasonable results. - Abstract: The purpose of this work is to validate the debris coolability analysis (DCA) module in the severe accident analysis code SAMPSON by simulating the first steady stage of the LIVE-L4 test. The DCA module is used for debris cooling in the lower plenum and for predicting the safety margin of present reactor vessels during a severe accident. In the DCA module, the spreading and cooling of molten debris, gap cooling, heating of a three-dimensional reactor vessel, and natural convection heat transfer are all considered. The LIVE experiment is designed to investigate the formation and stability of melt pools in a reactor pressure vessel (RPV). By comparing the simulation results and experimental data in terms of the average melt pool temperature and the heat flux along the vessel wall, a bug is found in the code and the model for the heat transfer between the melt pool and RPV wall is modified. Based on the Asfia–Dhir and Jahn–Reineke correlations, the modified version of the DCA module is found to give reasonable results for the average melt pool temperature, crust thickness in the steady state, and crust growth rate.

  20. Improvement of molten core-concrete interaction model of the debris spreading analysis model in the SAMPSON code - 15193

    International Nuclear Information System (INIS)

    Hidaka, M.; Fujii, T.; Sakai, T.

    2015-01-01

    A debris spreading analysis (DSA) module has been developed and improved. The module is used in the severe accident analysis code SAMPSON and it has models for 3-dimensional natural convection with simultaneous spreading, melting and solidification. The existing analysis method of the quasi-3D boundary transportation to simulate downward concrete erosion for evaluation of molten-core concrete interaction (MCCI) was improved to full-3D to solve, for instance, debris lateral erosion under concrete floors at the bottom of the sump pit. In the advanced MCCI model, buffer cells were defined in order to solve numerical problems in case of trammel formation. Mass, momentum, and the advection term of energy between the debris melt cells and the buffer cells are solved. On the other hand, only the heat transfer and thermal conduction are solved between the debris melt cells and the structure cells, and the crust cells and the structure cells. As a preliminary analysis, a validation calculation was performed for erosion that occurred in the core-concrete interaction (CCI-2) test in the OECD/MCCI program. Comparison between the calculation and the CCI-2 test results showed the analysis has the ability to simulate debris lateral erosion under concrete floors. (authors)

  1. Attenuation of airborne debris from LMFBR accidents

    International Nuclear Information System (INIS)

    Morewitz, H.A.; Johnson, R.P.; Nelson, C.T.; Vaughan, E.U.; Guderjahn, C.A.; Hilliard, R.K.; McCormack, J.D.; Postma, A.K.

    1978-01-01

    Experimental and theoretical studies have been performed to characterize the behavior of airborne particulates (aerosols) expected to be produced by hypothetical core disassembly accidents (HCDA's) in liquid metal fast breeder reactors (LMFBR's). These aerosol studies include work on aerosol transport in a 20-m high, 850-m 3 closed vessel at moderate concentrations; aerosol transport in a small vessel under conditions of high concentration (approximately 1,000 g/m 3 ), high turbulence, and high temperature (approximately 2000 0 C); and aerosol transport through various leak paths. These studies have shown that tittle, if any, airborne debris from LMFBR HCDA's would reach the atmosphere exterior to an intact reactor containment building. (author)

  2. Photometric Studies of Orbital Debris at GEO

    Science.gov (United States)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Ed; Abercromby, Kira J.; Foreman, Gary; Hortsman, Matt

    2009-01-01

    Orbital debris represents a significant and increasing risk to operational spacecraft. Here we report on photometric observations made in standard BVRI filters at the Cerro Tololo Inter-American Observatory (CTIO) in an effort to determine the physical characteristics of optically faint debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan s 0.6-m Curtis-Schmidt telescope (known as MODEST, for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. For a sample of 50 objects, calibrated sequences in RB- V-I-R filters have been obtained with the CTIO/SMARTS 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could imply that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For irregularly shaped objects tumbling at unknown orientations and rates, such sequential filter measurements using one telescope are subject to large errors for interpretation. If all observations in all filters in a particular sequence are of the same surface at the same solar and viewing angles, then the colors are meaningful. Where this is not the case, interpretation of the observed colors is impossible. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO/SMARTS 0.9-m observes in B, and the Schmidt in R. The CCD cameras are electronically linked together so that the start time and duration of observations are both the same to better than 50 milliseconds. Now the observed B-R color is a true measure of the scattered illuminated area of the debris piece for that observation.

  3. Engagement of Metal Debris into Gear Mesh

    Science.gov (United States)

    handschuh, Robert F.; Krantz, Timothy L.

    2010-01-01

    A series of bench-top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined.

  4. Engineering considerations in the use of artificial filter beds

    International Nuclear Information System (INIS)

    Richards, R.T.

    1978-01-01

    Artificial filter bed intakes utilize a prepared granular filter material to prevent entrance of debris and aquatic life into a water withdrawal facility. The relatively large quantities of water and the service reliability required for power plant cooling water systems present major engineering problems for the artificial filter concept, many of which have not been resolved. These problems include development of a suitable and stable filter medium; design of a reliable backwash system which is both effective and environmentally acceptable; meeting of all site-imposed restrictions relating to natural river turbidity, flooding characteristics, channel stability, and ice loads; and provision of the complex civil and mechanical engineering design inherent in such a system. Extensive model testing may be required for further engineering development of this system. The preliminary engineering for an artificial filter system is discussed in connection with a proposed 1.6-m 3 /s-capacity (25,000-gpm capacity) filter in the Columbia River

  5. Numerical simulation of the debris flow dynamics with an upwind scheme and specific friction treatment

    Science.gov (United States)

    Sánchez Burillo, Guillermo; Beguería, Santiago; Latorre, Borja; Burguete, Javier

    2014-05-01

    Debris flows, snow and rock avalanches, mud and earth flows are often modeled by means of a particular realization of the so called shallow water equations (SWE). Indeed, a number of simulation models have been already developed [1], [2], [3], [4], [5], [6], [7]. Debris flow equations differ from shallow water equations in two main aspects. These are (a) strong bed gradient and (b) rheology friction terms that differ from the traditional SWE. A systematic analysis of the numerical solution of the hyperbolic system of equations rising from the shallow water equations with different rheological laws has not been done. Despite great efforts have been done to deal with friction expressions common in hydraulics (such as Manning friction), landslide rheologies are characterized by more complicated expressions that may deal to unphysical solutions if not treated carefully. In this work, a software that solves the time evolution of sliding masses over complex bed configurations is presented. The set of non- linear equations is treated by means of a first order upwind explicit scheme, and the friction contribution to the dynamics is treated with a suited numerical scheme [8]. In addition, the software incorporates various rheological models to accommodate for different flow types, such as the Voellmy frictional model [9] for rock and debris avalanches, or the Herschley-Bulkley model for debris and mud flows. The aim of this contribution is to release this code as a free, open source tool for the simulation of mass movements, and to encourage the scientific community to make use of it. The code uses as input data the friction coefficients and two input files: the topography of the bed and the initial (pre-failure) position of the sliding mass. In addition, another file with the final (post-event) position of the sliding mass, if desired, can be introduced to be compared with the simulation obtained result. If the deposited mass is given, an error estimation is computed by

  6. Gas fluidized bed reactor

    International Nuclear Information System (INIS)

    Bernardelli, H. da C.

    1976-03-01

    The equations of motion for both gas and particles in a gas fluidised system are stablished through general assumptions which are generally accepted on physical grounds. The resulting model is used to study the velocity fields of each phase in the case of an isolated bubble rising close to the flat distributor plate. A well posed problem results for the solution of Laplace's equation of the potential flow of the particles when consideration is given to the presence of the distributor as a boundary condition. The corresponding stream functions are also obtained which enable the drawing of the motion patterns using numerical techniques. The following two dimensional cases are analysed: S/b=1; S/b=1,5; S/b=2,5; S/b=5 and the limiting case S/b→αinfinite. The results for the interphase exchange between bubbles and particulate phases are applied to a gas fluidised bed reactor and its effect on the chemical conversion is studied for the simplest cases of piston flow and perfect mixing in the particulate phase [pt

  7. Advantages of forced non-steady operated trickle-bed reactors

    NARCIS (Netherlands)

    Boelhouwer, J.G.; Piepers, H.W.; Drinkenburg, A.A.H.

    2002-01-01

    Trickle-bed reactors are usually operated in the steady state trickle flow regime. Uneven liquid distribution and the formation of hot spots are the most serious problems experienced during trickle flow operation. In this paper, we advocate the use of non-steady state operation of trickle-bed

  8. Chaotic hydrodynamics of fluidized beds

    Energy Technology Data Exchange (ETDEWEB)

    Van der Stappen, M.L.M. [Unit Process and Systems Engineering, Advanced Manufacturing Technology Group, Unilever Research Laboratorium, Vlaardingen (Netherlands)

    1996-12-31

    The major goals of this thesis are: (1) to develop and evaluate an analysis method based on techniques from non-linear chaos theory to characterize the nonlinear hydrodynamics of gas-solids fluidized beds quantitatively; and (2) to determine the dependence of the chaotic invariants on the operating conditions and investigate how the chaos analysis method can be profitably applied to improve scale-up and design of gas-solids fluidized bed reactors. Chaos theory is introduced in chapter 2 with emphasis on analysis techniques for (experimental) time series, known from literature at the start of this work (1990-1991). In chapter 3, the testing of existing and newly developed techniques on both model and fluidized bed data is described. This leads to the development of the chaos analysis method to analyze measured pressure fluctuations time series of a fluidized bed. Following, in chapter 4, this method is tested and all choices for the parameters are evaluated. The influence of the experimental parameters and external disturbances on the measurements and analysis results is discussed and quantified. The result is a chaos measurement and analysis protocol, which is further used in this work. In chapter 5, the applications to fluidized beds are discussed. It is shown that the entropy is a good measure for the characterization of the dynamical behavior of gas-solids bubbling/slugging fluidized beds. Entropy is applied to characterize the influence of the operating conditions, to assess regime transitions and to analyze dimensionless similar beds of different scale. Quantitative design correlations that relate entropy to the operating parameters (including the bed diameter) are described. Finally, it is discussed how the results of this work might be used in scaling up the chaotic dynamics of fluidized beds. The overall conclusions and outlook from this work are presented in chapter 6. 182 refs.

  9. Experimental investigations on friction laws and dryout heat flux of particulate beds packed with multi-size spheres and irregular particles

    International Nuclear Information System (INIS)

    Li, Liangxing; Ma, Weimin

    2011-01-01

    This paper is concerned with reducing uncertainty in quantification of debris bed coolability in a hypothetical severe accident of light water reactors (LWRs). A test facility named POMECO-FL is constructed to investigate the friction laws of adiabatic single and two-phase flow in a particulate bed packed with multi-size spheres or irregular particles. The same types of particles were then loaded in the test section of the POMECO-HT facility to obtain the dryout heat flux of the volumetrically heated particulate bed. The POMECO-HT facility features a high power capacity (up to 2.1 MW/m 2 ) which enables coolability study on particulate bed with broad variations in porosity and particle diameters under both top-flooding and bottom-injection conditions. The results show that given the effective particle diameter obtained from single-phase flow through the packed bed with multi-size spheres or irregular particles, both the pressure drop and the dryout heat flux of two-phase flow through the bed can be predicted by the Reed model. The bottom injection of coolant increases the dryout heat flux significantly. Meanwhile, the elevation of the dryout position is moving upwards with increasing bottom-injection flowrate. The experimental data provides insights for interpretation of debris bed coolability, as well as high-quality data for validation of the coolability analysis models and codes. (author)

  10. Bed retained products in swept fixed bed (SFB) coal hydropyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Mastral, A.M.; Perez-Surio, M.J. [CSIC, Zaragosa (Spain). Inst. de Carboquimica

    1997-12-31

    The hydropyrolysis of a low rank coal in a swept fixed bed (SFB) reactor is carried out by fixing the hydrogen pressure (40 kg/cm{sup 2}), the hydrogen flow (2 l/min) and the residence time (10 min) at increasing temperatures (400 C, 500 C and 600 C) and coal bed heights (h, 1.5h, 2h, 2.5h and 3h). It is shown that the percentages of tars and char directly depend on the coal bed height and that there is not only a quantitative dependence, but also the height of the coal bed is very important and plays a relevant role on the nature of the conversion products. (orig.)

  11. Bed diameter effects and incipient slugging in gas fluidized beds

    International Nuclear Information System (INIS)

    Agarwal, P.K.

    1986-01-01

    The coalescence and growth of bubble swarms formed at the distributor of a fluidized bed gives rise to lateral as well as vertical distributions of bubble properties. However, existing models employ average bubble properties obtained largely from semi-empirical considerations. In a recent Paper, the author developed a bubble growth model based on a population balance approach. Analytical expressions were derived for the bubble characteristic distributions and averages. However, the model, developed for unconstrained growth, did not take into account the effect of the bed diameter and the possibility of slugging. In this Paper, the model is extended to take these aspects into account. A slugging criterion is also developed which is expected to be valid for the regime where incipient slugging depends on the bed height as well as the region where bed height does not significantly affect minimum slugging conditions

  12. Investigation of Orbital Debris: Mitigation, Removal, and Modeling the Debris Population

    Science.gov (United States)

    Slotten, Joel

    The population of objects in orbit around Earth has grown since the late 1950s. Today there are over 21,000 objects over 10 cm in length in orbit, and an estimated 500,000 more between 1 and 10 cm. Only a small fraction of these objects are operational satellites. The rest are debris: old derelict spacecraft or rocket bodies, fragments created as the result of explosions or collisions, discarded objects, slag from solid rockets, or even flaked off paint. Traveling at up to 7 km/s, a collision with even a 1 cm piece of debris could severely damage or destroy a satellite. This dissertation examines three aspects of orbital debris. First, the concept of a self-consuming satellite is explored. This nanosatellite would use its own external structure as propellant to execute a deorbit maneuver at the end of its operational life, thus allowing it to meet current debris mitigation standards. Results from lab experiments examining potential materials for this concept have shown favorable results. Second, Particle in Cell techniques are modified and used to model the plasma plume from a micro-cathode arc thruster. This model is then applied to the concept of an ion beam shepherd satellite. This satellite would use its plasma plume to deorbit another derelict satellite. Results from these simulations indicate the micro-cathode arc thruster could potentially deorbit a derelict CubeSat in a matter of a few weeks. Finally, the orbital debris population at geosynchronous orbit is examined, focusing on variations in the density of the population as a function of longitude. New insights are revealed demonstrating that the variation in population density is slightly less than previously reported.

  13. Zodiac II: Debris Disk Science from a Balloon

    Science.gov (United States)

    Bryden, Geoffrey; Traub, Wesley; Roberts, Lewis C., Jr.; Bruno, Robin; Unwin, Stephen; Backovsky, Stan; Brugarolas, Paul; Chakrabarti, Supriya; Chen, Pin; Hillenbrand, Lynne; hide

    2011-01-01

    Zodiac II is a proposed balloon-borne science investigation of debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt (mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. Zodiac II will measure the size, shape, brightness, and color of a statistically significant sample of disks. These measurements will enable us to probe these fundamental questions: what do debris disks tell us about the evolution of planetary systems; how are debris disks produced; how are debris disks shaped by planets; what materials are debris disks made of; how much dust do debris disks make as they grind down; and how long do debris disks live? In addition, Zodiac II will observe hot, young exoplanets as targets of opportunity. The Zodiac II instrument is a 1.1-m diameter SiC (Silicone carbide) telescope and an imaging coronagraph on a gondola carried by a stratospheric balloon. Its data product is a set of images of each targeted debris disk in four broad visible-wavelength bands. Zodiac II will address its science questions by taking high-resolution, multi-wavelength images of the debris disks around tens of nearby stars. Mid-latitude flights are considered: overnight test flights in the US followed by half-global flights in the Southern Hemisphere. These longer flights are required to fully explore the set of known debris disks accessible only to Zodiac II. On these targets, it will be 100 times more sensitive than the Hubble Space Telescope's Advanced Camera for Surveys (HST/ACS); no existing telescope can match the Zodiac II contrast and resolution performance. A second objective of Zodiac II is to use the near-space environment to raise the Technology Readiness Level (TRL) of SiC mirrors, internal coronagraphs, deformable mirrors, and wavefront sensing and control, all potentially needed for a future space-based telescope for high-contrast exoplanet imaging.

  14. Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

    Science.gov (United States)

    Marquis, G. A.; Roy, A. G.

    2012-02-01

    This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

  15. Early deterioration of coarse woody debris.

    Energy Technology Data Exchange (ETDEWEB)

    Tainter, Frank, H.; McMinn, James, W.

    1999-02-16

    Tainter, F.H., and J.W. McMinn. 1999. Early deterioration of coarse woody debris. In: Proc. Tenth Bien. South. Silv. Res. Conf. Shreveport, LA, February 16-18, 1999. Pp. 232-237 Abstract - Coarse woody debris (CWD) is an important structural component of southern forest ecosystems. CWD loading may be affected by different decomposition rates on sites of varying quality. Bolts of red oak and loblolly pine were placed on plots at each of three (hydric, mesic. and xerlc) sites at the Savannah River Site and sampled over a I6-week period. Major changes were in moisture content and nonstructural carbohydrate content (total carbohydrates, reducing sugars, and starch) of sapwood. Early changes in nonstructural carbohydrate levels following placement of the bolts were likely due to reallocation of these materials by sapwood parenchyma cells. These carbohydrates later formed pools increasingly metabolized by bacteria and invading fungi. Most prevalent fungi in sapwood were Ceratocysfis spp. in pine and Hypoxy/on spp. in oak. Although pine sapwood became blue stained and oak sapwood exhibited yellow soft decay with black zone lines, estimators of decay (specific gravity, sodium hydroxide solubility, and holocellulose content) were unchanged during the 16-week study period. A small effect of site was detected for starch content of sapwood of both species. Fungal biomass in sapwood of both species, as measured by ergosterol content, was detectable at week zero, increased somewhat by week three and increased significantly by week 16.

  16. A PRIMER ON UNIFYING DEBRIS DISK MORPHOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eve J.; Chiang, Eugene, E-mail: evelee@berkeley.edu, E-mail: echiang@astro.berkeley.edu [Department of Astronomy, University of California Berkeley, Berkeley, CA 94720-3411 (United States)

    2016-08-20

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  17. A PRIMER ON UNIFYING DEBRIS DISK MORPHOLOGIES

    International Nuclear Information System (INIS)

    Lee, Eve J.; Chiang, Eugene

    2016-01-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  18. A Primer on Unifying Debris Disk Morphologies

    Science.gov (United States)

    Lee, Eve J.; Chiang, Eugene

    2016-08-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  19. Critical comparison of hydrodynamic models for gas-solid fluidized beds - Part II: freely bubbling gas-solid fluidized beds

    NARCIS (Netherlands)

    Patil, D.J.; van Sint Annaland, M.; Kuipers, J.A.M.

    2005-01-01

    Correct prediction of spontaneous bubble formation in freely bubbling gas¿solid fluidized beds using Eulerian models, strongly depends on the description of the internal momentum transfer in the particulate phase. In this part, the comparison of the simple classical model, describing the solid phase

  20. Space Debris Alert System for Aviation

    Science.gov (United States)

    Sgobba, Tommaso

    2013-09-01

    Despite increasing efforts to accurately predict space debris re-entry, the exact time and location of re-entry is still very uncertain. Partially, this is due to a skipping effect uncontrolled spacecraft may experience as they enter the atmosphere at a shallow angle. Such effect difficult to model depends on atmospheric variations of density. When the bouncing off ends and atmospheric re-entry starts, the trajectory and the overall location of surviving fragments can be precisely predicted but the time to impact with ground, or to reach the airspace, becomes very short.Different is the case of a functional space system performing controlled re-entry. Suitable forecasts methods are available to clear air and maritime traffic from hazard areas (so-called traffic segregation).In US, following the Space Shuttle Columbia accident in 2003, a re-entry hazard areas location forecast system was putted in place for the specific case of major malfunction of a Reusable Launch Vehicles (RLV) at re-entry. The Shuttle Hazard Area to Aircraft Calculator (SHAAC) is a system based on ground equipment and software analyses and prediction tools, which require trained personnel and close coordination between the organization responsible for RLV operation (NASA for Shuttle) and the Federal Aviation Administration. The system very much relies on the operator's capability to determine that a major malfunction has occurred.This paper presents a US pending patent by the European Space Agency, which consists of a "smart fragment" using a GPS localizer together with pre- computed debris footprint area and direct broadcasting of such hazard areas.The risk for aviation from falling debris is very remote but catastrophic. Suspending flight over vast swath of airspace for every re-entering spacecraft or rocket upper stage, which is a weekly occurrence, would be extremely costly and disruptive.The Re-entry Direct Broadcasting Alert System (R- DBAS) is an original merging and evolution of the Re