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Sample records for reactivity transient experiments

  1. Transient debris freezing and potential wall melting during a severe reactivity initiated accident experiment

    International Nuclear Information System (INIS)

    El-Genk, M.S.; Moore, R.L.

    1981-01-01

    It is important to light water reactor (LWR) safety analysis to understand the transient freezing of molten core debris on cold structures following a hypothetical core meltdown accident. The purpose of this paper is to (a) present the results of a severe reactivity initiated accident (RIA) in-pile experiment with regard to molten debris distribution and freezing following test fuel rod failure, (b) analyze the transient freezing of molten debris (primarily a mixture of UO/sub 2/ fuel and Zircaloy cladding) deposited on the inner surface of the test shroud wall upon rod failure, and (c) assess the potential for wall melting upon being contacted by the molten debris. 26 refs

  2. Study on reactor power transient characteristics (reactor training experiments). Control rod reactivity calibration by positive period method and other experiment

    International Nuclear Information System (INIS)

    Ozaki, Yoshihiko; Sunagawa, Takeyoshi

    2014-01-01

    In this paper, it is reported about some experiments that have been carried out in the reactor training that targets sophomore of the department of applied nuclear engineering, FUT. Reactor of Kinki University Atomic Energy Research Institute (UTR-KINKI) was used for reactor training. When each critical state was achieved at different reactor output respectively in reactor operating, it was confirmed that the control rod position at that time does not change. Further, control rod reactivity calibration experiments using positive Period method were carried out for shim safety rod and regulating rod, respectively. The results were obtained as reasonable values in comparison with the nominal value of the UTR-KINKI. The measurement of reactor power change after reactor scram was performed, and the presence of the delayed neutron precursor was confirmed by calculating the half-life. The spatial dose rate measurement experiment of neutrons and γ-rays in the reactor room in a reactor power 1W operating conditions were also performed. (author)

  3. Reactivity transient calculatios in research reactor

    International Nuclear Information System (INIS)

    Santos, R.S. dos

    1986-01-01

    A digital program for reactivity transient analysis in research reactor and cylindrical geometry was showed quite efficient when compared with methods and programs of the literature, as much in the solution of the neutron kinetics equation as in the thermohydraulic. An improvement in the representation of the feedback reactivity adopted on the program reduced markedly the computation time, with some accuracy. (Author) [pt

  4. RETRANS, Reactivity Transients in LWR

    International Nuclear Information System (INIS)

    Kamelander, G.

    1989-01-01

    1 - Description of program or function: RETRANS is appropriate to calculate power excursions in light water reactors initiated by reactivity insertions due to withdrawal of control elements. As in the code TWIGL, the neutron physics model is based on the time-dependent two-group neutron diffusion equations. The equation of state of the coolant is approximated by a table built into the code. RETRANS solves the heat conduction equation and calculates the heat transfer coefficient for representative fuel rods at each time-step. 2 - Method of solution: The time-dependent neutron diffusion equations are modified by an exponential transformation and solved by means of a finite difference method. There is an option accelerating the inner iterations of the difference scheme by a coarse-mesh re-balancing method. The heat balance equations of the thermo- hydraulic model are discretized and converted into a tri-diagonal system of linear equations which is solved recursively. 3 - Restrictions on the complexity of the problem: r-z-geometry, one- phase-flow

  5. TRACY transient experiment databook. 2) ramp withdrawal experiment

    International Nuclear Information System (INIS)

    Nakajima, Ken; Yamane, Yuichi; Ogawa, Kazuhiko; Aizawa, Eiju; Yanagisawa, Hiroshi; Miyoshi, Yoshinori

    2002-03-01

    This is a databook of TRACY ''ramp withdrawal'' experiments. TRACY is a reactor to perform supercritical experiments using low-enriched uranyl nitrate aqueous solution. The excess reactivity of TRACY is 3$ at maximum, and it is inserted by feeding the solution to a core tank or by withdrawing a control rod, which is called as the transient rod, from the core. In the ramp withdrawal experiment, the supercritical experiment is initiated by withdrawing the transient rod from the core in a constant speed using a motor drive system. The data in the present databook consist of datasheets and graphs. Experimental conditions and typical values of measured parameters are tabulated in the datasheet. In the graph, power and temperature profiles are plotted. Those data are useful for the investigation of criticality accidents with fissile solutions, and for validation of criticality accident analysis codes. (author)

  6. Characteristics and use of the transient reactivity meter

    International Nuclear Information System (INIS)

    Yarbrough, W.M.

    1982-10-01

    At EG and G Idaho reactor facilities, reactivity measurements - an essential part of experimental reactor physics - are performed on line using an analog device known as the transient reactivity meter (TRM). The TRM has certain features that set it apart from most other instruments of its kind. This document describes these features and presents procedural information valuable to those who set up and use the TRM in a reactor measurement system

  7. RELAP5-3D code validation of RBMK-1500 reactor reactivity measurement transients

    International Nuclear Information System (INIS)

    Kaliatka, Algirdas; Bubelis, Evaldas; Uspuras, Eugenijus

    2003-01-01

    This paper deals with the modeling of transients taking place during the measurements of the void and fast power reactivity coefficients performed at Ignalina NPP. The simulation of these transients was performed using RELAP5-3D code model of RBMK-1500 reactor. At the Ignalina NPP void and fast power reactivity coefficients are measured on a regular basis and, based on the total reactor power, reactivity, control and protection system control rods positions and the main circulation circuit parameter changes during the experiments, the actual values of these reactivity coefficients are determined. Following the simulation of the two above mentioned transients with RELAP5-3D code, a conclusion was made that the obtained calculation results demonstrate reasonable agreement with Ignalina NPP measured data. Behaviors of the separate MCC thermal-hydraulic parameters as well as physical processes are predicted reasonably well to the real processes, occurring in the primary circuit of RBMK-1500 reactor. The calculated reactivity and the total reactor core power behavior in time are also in reasonable agreement with the measured plant data. Despite of the small differences, RELAP5-3D code predicts reactivity and the total reactor core power behavior during the transients in a reasonable manner. Reasonable agreement of the measured and the calculated total reactor power change in time demonstrates the correct modeling of the neutronic processes taking place in RBMK-1500 reactor core

  8. TRACY transient experiment databook. 3) Ramp feed experiment

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Ken; Yamane, Yuichi; Ogawa, Kazuhiko; Aizawa, Eiju; Yanagisawa, Hiroshi; Miyoshi, Yoshinori [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2002-03-01

    This is a databook of TRACY ''ramp feed'' experiments. TRACY is a reactor to perform supercritical experiments using low-enriched uranyl nitrate aqueous solution. The excess reactivity of TRACY is 3$ at maximum, and it is inserted by feeding the solution to a core tank or by withdrawing a control rod, which is called as the transient rod, from the core. In the ramp feed experiment, the supercritical experiment is initiated by feeding the fuel solution to the core tank in a constant feed rate. The data in the present databook consist of datasheets and graphs. Experimental conditions and typical values of measured parameters are tabulated in the datasheet. In the graph, power and temperature profiles are plotted. Those data are useful for the investigation of criticality accidents with fissile solutions, and for validation of criticality accident analysis codes. (author)

  9. AIREKMOD-RR, Reactivity Transients in Nuclear Research Reactors

    International Nuclear Information System (INIS)

    Baggoura, B.; Mazrou, H.

    2001-01-01

    1 - Description of program or function: AIREMOD-RR is a point kinetics code which can simulate fast transients in nuclear research reactor cores. It can also be used for theoretical reactor dynamics studies. It is used for research reactor kinetic analysis and provides a point neutron kinetic capability. The thermal hydraulic behavior is governed by a one-dimensional heat balance equation. The calculations are restricted to a single equivalent unit cell which consists of fuel, clad and coolant. 2 - Method of solution: For transient reactor kinetic calculations a modified Runge Kutta numerical method is used. The external reactivity insertion, specified as a function of time, is converted in dollar ($) unit. The neutron density, energy release and feedback variables are given at each time step. The two types of reactivity feedback considered are: Doppler effect and moderator effect. A new expression for the reactivity dependence on the feedback variables has been introduced in the present version of the code. The feedback reactivities are fitted in power series expression. 3 - Restrictions on the complexity of the problem: The number of delayed neutron groups and the total number of equations are limited only by computer storage capabilities. - Coolant is always in liquid phase. - Void reactivity feedback is not considered

  10. Proceedings of a specialist meeting on boron reactivity transients

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    The CSNI Specialist Meeting on Boron Dilution Reactivity Transients was hosted by the Penn State University in collaboration with the US Nuclear Regulatory Commission and the TRAC Users Group. More than 70 experts from 12 OECD countries, as well as experts from Russia and other non-OECD countries attended the meeting. Thirty papers were presented in five technical sessions. The purpose of the meeting was to bring together experts involved in the different activities related to boron dilution transients. The experts came from all involved parties, including research organizations, regulatory authorities, vendors and utilities. Information was openly shared and discussed on the experimental results, plant and systems analysis, numerical analysis of mixing and probability and consequences of these transients. Regulatory background and licensing implications were also included to provide the proper frame work for the technical discussion. Each of these areas corresponded to a separate session. The meeting focused on the thermal-hydraulic aspects because of the current interest in that subject and the significant amount of new technical information being generated. Three papers of the same conference are already available in INIS as individual reports: Potential for boron dilution during small-break LOCAs in PWRs (Ref. number: 27029412); Analysis of boron dilution in a four-loop PWR (Ref. number: 27051651); Probability and consequences of a rapid boron dilution sequence in a PWR (Ref. number: 27029411)

  11. Analysis of reactivity transient for the DIDO type research reactors using RELAP5

    International Nuclear Information System (INIS)

    Adorni, M.; Bousbia-Salah, A.; D'Auria, F.; Nabbi, R.

    2005-01-01

    Recent availability of high performance computers and computational methods together with the continuing increase in operational experience imposes revising some operational constrains and conservative safety margins. The application of Best-Estimate (BE) method constitutes a real necessity in the safety and design analysis and allows getting more realistic simulation of the processes taking place during the steady state operation and transients. In comparison to the conservative approaches, the application of Best-Estimate methods results in the mitigation of the constraining limits in design and operation. This paper presents the results of the application of the RELAP5/Mod3.3 system thermal-hydraulic code to the German FRJ-2 research reactor for a reactivity transient, which has been analyzed in the past using the verified system code CATHENA [1], [2], [3]. The work mainly aims checking the capability of RELAP5 [4] for research reactor transient analysis by the comparison of the results of the two codes and including modeling basis and analytical approaches. According to the existing references RELAP5 applications are concentrated on the transient analysis of nuclear power systems. The considered case consists of a simulation related to a hypothetical fast reactivity transient, which is assumed to be caused by the failure of one shutdown arm. The case has been chosen due to the importance of the models for the precise description of the complex phenomenon of subcooled boiling and two phase flow taking place during the transient. For this purpose, the fuel element assembly was modeled in detail according to design data. The primary circuit was included in the whole model in order to consider the interaction with individual fuel elements with core. In general the results of the two codes are in agreement and comparable during the initial phase of the transient. After reaching the flow regime with fully developed nucleate boiling and two phase flow RELAP5 exhibits

  12. Anticipated transient without SCRAM experiments at LOFT

    International Nuclear Information System (INIS)

    Grush, W.H.; Harvego, E.A.; Koizumi, Y.; Varacalle, D.J.

    1983-01-01

    This paper discusses the experimental results for two anticipated transients without scram (ATWS) experiments, and compares computer code predictions with the experimental data. Experiment L9-3 simulated an ATWS in a commercial pressurized water reactor (PWR) initiated by a complete loss of feedwater and Experiment L9-4 simulated a loss-of-offsite-power-initiated (loss of feedwater and trip of the primary coolant pumps) ATWS. The LOFT facility is uniquely suited for ATWS experiments because it is a volumetrically scaled (1/44) experimental PWR designed to simulate the major components and system responses of larger commercial PWRs during both hypothesized loss-of-coolant accidents and anticipated transients. In both of the examined experiments, the primary system transient behavior was dominated by the interactions between the steam generator primary-to-secondary heat removal, the reactor kinetics, and the relief valve actuation. It is demonstrated that the discussed ATWS events can be controlled by properly sized automatic safety systems

  13. Transient Simulation of the Multi-SERTTA Experiment with MAMMOTH

    International Nuclear Information System (INIS)

    Ortensi, Javier; Baker, Benjamin; Wang, Yaqi; Schunert, Sebastian; DeHart, Mark

    2017-01-01

    This work details the MAMMOTH reactor physics simulations of the Static Environment Rodlet Transient Test Apparatus (SERTTA) conducted at Idaho National Laboratory in FY-2017. TREAT static-environment experiment vehicles are being developed to enable transient testing of Pressurized Water Reactor (PWR) type fuel specimens, including fuel concepts with enhanced accident tolerance (Accident Tolerant Fuels, ATF). The MAMMOTH simulations include point reactor kinetics as well as spatial dynamics for a temperature-limited transient. The strongly coupled multi-physics solutions of the neutron flux and temperature fields are second order accurate both in the spatial and temporal domains. MAMMOTH produces pellet stack powers that are within 1.5% of the Monte Carlo reference solutions. Some discrepancies between the MCNP model used in the design of the flux collars and the Serpent/MAMMOTH models lead to higher power and energy deposition values in Multi-SERTTA unit 1. The TREAT core results compare well with the safety case computed with point reactor kinetics in RELAP5-3D. The reactor period is 44 msec, which corresponds to a reactivity insertion of 2.685% delta k/k$. The peak core power in the spatial dynamics simulation is 431 MW, which the point kinetics model over-predicts by 12%. The pulse width at half the maximum power is 0.177 sec. Subtle transient effects are apparent at the beginning insertion in the experimental samples due to the control rod removal. Additional difference due to transient effects are observed in the sample powers and enthalpy. The time dependence of the power coupling factor (PCF) is calculated for the various fuel stacks of the Multi-SERTTA vehicle. Sample temperatures in excess of 3100 K, the melting point UO$ 2 $, are computed with the adiabatic heat transfer model. The planned shaped-transient might introduce additional effects that cannot be predicted with PRK models. Future modeling will be focused on the shaped-transient by improving the

  14. Transient Simulation of the Multi-SERTTA Experiment with MAMMOTH

    Energy Technology Data Exchange (ETDEWEB)

    Ortensi, Javier [Idaho National Lab. (INL), Idaho Falls, ID (United States); Baker, Benjamin [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Yaqi [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schunert, Sebastian [Idaho National Lab. (INL), Idaho Falls, ID (United States); deHart, Mark [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-07-11

    This work details the MAMMOTH reactor physics simulations of the Static Environment Rodlet Transient Test Apparatus (SERTTA) conducted at Idaho National Laboratory in FY-2017. TREAT static-environment experiment vehicles are being developed to enable transient testing of Pressurized Water Reactor (PWR) type fuel specimens, including fuel concepts with enhanced accident tolerance (Accident Tolerant Fuels, ATF). The MAMMOTH simulations include point reactor kinetics as well as spatial dynamics for a temperature-limited transient. The strongly coupled multi-physics solutions of the neutron flux and temperature fields are second order accurate both in the spatial and temporal domains. MAMMOTH produces pellet stack powers that are within 1.5% of the Monte Carlo reference solutions. Some discrepancies between the MCNP model used in the design of the flux collars and the Serpent/MAMMOTH models lead to higher power and energy deposition values in Multi-SERTTA unit 1. The TREAT core results compare well with the safety case computed with point reactor kinetics in RELAP5-3D. The reactor period is 44 msec, which corresponds to a reactivity insertion of 2.685% delta k/k$. The peak core power in the spatial dynamics simulation is 431 MW, which the point kinetics model over-predicts by 12%. The pulse width at half the maximum power is 0.177 sec. Subtle transient effects are apparent at the beginning insertion in the experimental samples due to the control rod removal. Additional difference due to transient effects are observed in the sample powers and enthalpy. The time dependence of the power coupling factor (PCF) is calculated for the various fuel stacks of the Multi-SERTTA vehicle. Sample temperatures in excess of 3100 K, the melting point UO$_2$, are computed with the adiabatic heat transfer model. The planned shaped-transient might introduce additional effects that cannot be predicted with PRK models. Future modeling will be focused on the shaped-transient by improving the

  15. Experience with transients in German NPPs

    International Nuclear Information System (INIS)

    Lindauer, E.

    1984-01-01

    This chapter examines reactor accidents in the Federal Republic of Germany based on the formal reporting system for licensee event reports (LERs) and a special investigation on all unplanned power variations in 3 PWRs. The significant transients experienced by BWR type reactors are analyzed. The main goal is to find weak points which caused the transient or influenced its course in an unfavorable way in order to improve the affected plant and others. The complete survey of all transients, with normally little or no safety relevance, allows statistical evaluations and the analysis of trends. It is concluded that significant transients were mainly experienced at older plants, whereas plants of an advanced design produced very few significant transients. The most frequent human errors which lead to transients are failure search in electronic systems and errors during design and commissioning

  16. Neutron and thermo - hydraulic model of a reactivity transient in a nuclear power plant fuel element

    International Nuclear Information System (INIS)

    Oliva, Jose de Jesus Rivero

    2012-01-01

    A reactivity transient without reactor scram was modeled and calculated using analytical expressions for the space distributions of the temperature fields, combined with discrete numerical calculations for the time dependences of thermal power and temperatures. The transient analysis covered the time dependencies of reactivity, global thermal power, fuel heat flux and temperatures in fuel, cladding and cooling water. The model was implemented in Microsoft Office Excel, dividing the Excel file in several separated worksheets for input data, initial steady-state calculations, calculation of parameters non-depending on eigenvalues, eigenvalues determination, calculation of parameters depending on eigenvalues, transient calculation and graphical representation of intermediate and final results. The results show how the thermal power reaches a new equilibrium state due to the negative reactivity feedback derived from the fuel temperature increment. Nevertheless, the reactor mean power increases 40% during the first second and, in the hottest channel, the maximum fuel temperature goes to a significantly high value, slightly above 2100 deg C, after 8 seconds of transient. Consequently, the results confirm that certain degree of fuel damage could be expected in case of a reactor scram failure. Once the basic model has being established the scope of accidents for future analyses can be extended, modifying the nuclear power behavior (reactivity) during transient and the boundary conditions for coolant temperature. A more complex model is underway for an annular fuel element. (author)

  17. Flow transients experiments with refrigerant-12

    International Nuclear Information System (INIS)

    Celata, G.P.; D'Annibale, F.; Farello, G.E.; Setaro, T.

    1986-01-01

    Flow transients have been investigated in a wide range of thermal-hydraulics situations with Refrigerannt-12. Six pressures (including the reference to PWR and BWR characteristic liquid to vapour densities ratios), several periods of the flowrate transients coastdown during the simulated flow decays, and different specific mass flowrate have been studied emploiyng a circular duct test section (Dsub(i)=7,5 mm). Two heated lengths of the test section have been considered (L = 2300 and 1180 mm). Experimental data have shown the complete inadequacy of steady-state critical heat flux correlations in predicting the onset of boiling crisis during fast flow transients (half-flow decay time, tsub(h)lt5.0-6.0 s). The flow transient does not show dependence, in terms of DNB conditions ,upon the length of the test section: the ratio between transient and steady-state critical mass flowrate is not dependent on the tested geometry. The time interval from the start of the flowrate transient to the onset of DNB (time to crisis), has been experimentally determined for all the runs. Data analysis for a better theoretical prediction of the phenomenon has been accomplished, and a design correlation for DNB conditons and time to crisis prediction has been proposed

  18. On RELAP5-simulated High Flux Isotope Reactor reactivity transients: Code change and application

    International Nuclear Information System (INIS)

    Freels, J.D.

    1993-01-01

    This paper presents a new and innovative application for the RELAP5 code (hereafter referred to as ''the code''). The code has been used to simulate several transients associated with the (presently) draft version of the High-Flux Isotope Reactor (HFIR) updated safety analysis report (SAR). This paper investigates those thermal-hydraulic transients induced by nuclear reactivity changes. A major goal of the work was to use an existing RELAP5 HFIR model for consistency with other thermal-hydraulic transient analyses of the SAR. To achieve this goal, it was necessary to incorporate a new self-contained point kinetics solver into the code because of a deficiency in the point-kinetics reactivity model of the Mod 2.5 version of the code. The model was benchmarked against previously analyzed (known) transients. Given this new code, four event categories defined by the HFIR probabilistic risk assessment (PRA) were analyzed: (in ascending order of severity) a cold-loop pump start; run-away shim-regulating control cylinder and safety plate withdrawal; control cylinder ejection; and generation of an optimum void in the target region. All transients are discussed. Results of the bounding incredible event transient, the target region optimum void, are shown. Future plans for RELAP5 HFIR applications and recommendations for code improvements are also discussed

  19. Interpreting signals from astrophysical transient experiments.

    Science.gov (United States)

    O'Brien, Paul T; Smartt, Stephen J

    2013-06-13

    Time-domain astronomy has come of age with astronomers now able to monitor the sky at high cadence, both across the electromagnetic spectrum and using neutrinos and gravitational waves. The advent of new observing facilities permits new science, but the ever-increasing throughput of facilities demands efficient communication of coincident detections and better subsequent coordination among the scientific community so as to turn detections into scientific discoveries. To discuss the revolution occurring in our ability to monitor the Universe and the challenges it brings, on 25-26 April 2012, a group of scientists from observational and theoretical teams studying transients met with representatives of the major international transient observing facilities at the Kavli Royal Society International Centre, UK. This immediately followed the Royal Society Discussion Meeting 'New windows on transients across the Universe' held in London. Here, we present a summary of the Kavli meeting at which the participants discussed the science goals common to the transient astronomy community and analysed how to better meet the challenges ahead as ever more powerful observational facilities come on stream.

  20. Research of three-dimensional transient reactivity feedback in fast reactor

    International Nuclear Information System (INIS)

    Xu Li; Shi Gong; Ma Dayuan; Yu Hong

    2013-01-01

    To solve the three-dimensional time-spatial kinetics feedback problems in fast reactor, a mathematical model of the direct reactivity feedback was proposed. Based on the NAS code for fast reactor and the reactivity feedback mechanism, a feedback model which combined the direct reactivity feedback and feedback reflected by the cross section variation was provided for the transient calculation. Furthermore, the fast reactor group collapsing system was added to the code, thus the real time group collapsing calculation could be realized. The isothermal elevated temperature test of CEFR was simulated by using the code. By comparing the calculation result with the test result of the temperature reactivity coefficient, the validity of the model and the code is verified. (authors)

  1. Searching for MHz Transients with the VLA Low-band Ionosphere and Transient Experiment (VLITE)

    Science.gov (United States)

    Polisensky, Emil; Peters, Wendy; Giacintucci, Simona; Clarke, Tracy; Kassim, Namir E.; hyman, Scott D.; van der Horst, Alexander; Linford, Justin; Waldron, Zach; Frail, Dale

    2018-01-01

    NRL and NRAO have expanded the low frequency capabilities of the VLA through the VLA Low-band Ionosphere and Transient Experiment (VLITE, http://vlite.nrao.edu/ ), effectively making the instrument two telescopes in one. VLITE is a commensal observing system that harvests data from the prime focus in parallel with normal Cassegrain focus observing on a subset of VLA antennas. VLITE provides over 6000 observing hours per year in a > 5 square degree field-of-view using 64 MHz bandwidth centered on 352 MHz. By operating in parallel, VLITE offers invaluable low frequency data to targeted observations of transient sources detected at higher frequencies. With arcsec resolution and mJy sensitivity, VLITE additionally offers great potential for blind searches of rarer radio-selected transients. We use catalog matching software on the imaging products from the daily astrophysics pipeline and the LOFAR Transients Pipeline (TraP) on repeated observations of the same fields to search for coherent and incoherent astronomical transients on timescales of a few seconds to years. We present the current status of the VLITE transient science program from its initial deployment on 10 antennas in November 2014 through its expansion to 16 antennas in the summer of 2017. Transient limits from VLITE’s first year of operation (Polisensky et al. 2016) are updated per the most recent analysis.

  2. Development of a reactivity worth correction scheme for the one-dimensional transient analysis

    International Nuclear Information System (INIS)

    Cho, J. Y.; Song, J. S.; Joo, H. G.; Kim, H. Y.; Kim, K. S.; Lee, C. C.; Zee, S. Q.

    2003-11-01

    This work is to develop a reactivity worth correction scheme for the MASTER one-dimensional (1-D) calculation model. The 1-D cross section variations according to the core state in the MASTER input file, which are produced for 1-D calculation performed by the MASTER code, are incorrect in most of all the core states except for exactly the same core state where the variations are produced. Therefore this scheme performs the reactivity worth correction factor calculations before the main 1-D transient calculation, and generates correction factors for boron worth, Doppler and moderator temperature coefficients, and control rod worth, respectively. These correction factors force the one dimensional calculation to generate the same reactivity worths with the 3-dimensional calculation. This scheme is applied to the control bank withdrawal accident of Yonggwang unit 1 cycle 14, and the performance is examined by comparing the 1-D results with the 3-D results. This problem is analyzed by the RETRAN-MASTER consolidated code system. Most of all results of 1-D calculation including the transient power behavior, the peak power and time are very similar with the 3-D results. In the MASTER neutronics computing time, the 1-D calculation including the correction factor calculation requires the negligible time comparing with the 3-D case. Therefore, the reactivity worth correction scheme is concluded to be very good in that it enables the 1-D calculation to produce the very accurate results in a few computing time

  3. Reactive power generation in high speed induction machines by continuously occurring space-transients

    Science.gov (United States)

    Laithwaite, E. R.; Kuznetsov, S. B.

    1980-09-01

    A new technique of continuously generating reactive power from the stator of a brushless induction machine is conceived and tested on a 10-kw linear machine and on 35 and 150 rotary cage motors. An auxiliary magnetic wave traveling at rotor speed is artificially created by the space-transient attributable to the asymmetrical stator winding. At least two distinct windings of different pole-pitch must be incorporated. This rotor wave drifts in and out of phase repeatedly with the stator MMF wave proper and the resulting modulation of the airgap flux is used to generate reactive VA apart from that required for magnetization or leakage flux. The VAR generation effect increases with machine size, and leading power factor operation of the entire machine is viable for large industrial motors and power system induction generators.

  4. A transient overpower experiment in EBR-II

    International Nuclear Information System (INIS)

    Herzog, J.P.; Tsai, H.; Dean, E.M.; Aoyama, T.; Yamamoto, K.

    1994-01-01

    The TOPI-IE test was a transient overpower test on irradiate mixed-oxide fuel pins in the Experimental Breeder Reactor-II (EBR-II). The test, the fifth in a series, was part of a cooperative program between the US Department of Energy and the Power Reactor and Nuclear Fuel Development Corporation of Japan to conduct operational transient testing on mixed-oxide fuel pins in the metal-fueled EBR-II. The principle objective of the TOPI-1E test was to assess breaching margins for irradiated mixed-oxide fuel pins over the Plant Protection System (PPS) thresholds during a slow, extended overpower transient. This paper describes the effect of the TOPI-1E experiment on reactor components and the impact of the experiment on the long-term operability of the reactor. The paper discusses the role that SASSYS played in the pre-test safety analysis of the experiment. The ability of SASSYS to model transient overpower events is detailed by comparisons of data from the experiment with computed reactor variables from a SASSYS post-test simulation of the experiment

  5. Calculations of steady-state and reactivity insertion transients in a research reactor simulating the PWR

    International Nuclear Information System (INIS)

    Mladin, Mirea; Mladin, Daniela; Prodea, Ilie

    2010-01-01

    In 2008, IAEA started a Coordinated Research Project for benchmarking the thermalhydraulic and neutronic computer codes for research reactor analysis against the experimental data. In this framework, for the first year of research contract, the Institute for Nuclear Research engaged in steady-state analysis of SPERT-III reactor and also in the simulation of the reactivity insertion tests performed in this reactor during mid sixties. In the first part, the paper describes a Monte Carlo input model of the oxide core selected for investigation and the results of the steady-state neutronic calculations with respect to hot and cold core reactivity excess and control rods worth. Also, prompt neutron life and reactivity feed-back coefficients were examined. These results were compared with the data provided in the reactor specification document concerning neutronic design calculated data. The second part of the paper is dedicated to calculation of the reactivity insertion transients with RELAP5 and CATHARE2 thermalhydraulic codes, both including point reactor kinetics models, and to comparison with experimental data. (authors)

  6. Reactivity estimation using digital nonlinear H∞ estimator for VHTRC experiment

    International Nuclear Information System (INIS)

    Suzuki, Katsuo; Nabeshima, Kunihiko; Yamane, Tsuyoshi

    2003-01-01

    On-line and real-time estimation of time-varying reactivity in a nuclear reactor in necessary for early detection of reactivity anomaly and safe operation. Using a digital nonlinear H ∞ estimator, an experiment of real-time dynamic reactivity estimation was carried out in the Very High Temperature Reactor Critical Assembly (VHTRC) of Japan Atomic Energy Research Institute. Some technical issues of the experiment are described, such as reactivity insertion, data sampling frequency, anti-aliasing filter, experimental circuit and digitalising nonlinear H ∞ reactivity estimator, and so on. Then, we discussed the experimental results obtained by the digital nonlinear H ∞ estimator with sampled data of the nuclear instrumentation signal for the power responses under various reactivity insertions. Good performances of estimated reactivity were observed, with almost no delay to the true reactivity and sufficient accuracy between 0.05 cent and 0.1 cent. The experiment shows that real-time reactivity for data sampling period of 10 ms can be certainly realized. From the results of the experiment, it is concluded that the digital nonlinear H ∞ reactivity estimator can be applied as on-line real-time reactivity meter for actual nuclear plants. (author)

  7. Cerebral vasomotor reactivity: steady-state versus transient changes in carbon dioxide tension.

    Science.gov (United States)

    Brothers, R Matthew; Lucas, Rebekah A I; Zhu, Yong-Sheng; Crandall, Craig G; Zhang, Rong

    2014-11-01

    Cerebral vasomotor reactivity (CVMR) to changes in arterial carbon dioxide tension (P aCO 2) is assessed during steady-state or transient changes in P aCO 2. This study tested the following two hypotheses: (i) that CVMR during steady-state changes differs from that during transient changes in P aCO 2; and (ii) that CVMR during rebreathing-induced hypercapnia would be blunted when preceded by a period of hyperventilation. For each hypothesis, end-tidal carbon dioxide tension (P ET , CO 2) middle cerebral artery blood velocity (CBFV), cerebrovascular conductance index (CVCI; CBFV/mean arterial pressure) and CVMR (slope of the linear regression between changes in CBFV and CVCI versus P ET , CO 2) were assessed in eight individuals. To address the first hypothesis, measurements were made during the following two conditions (randomized): (i) steady-state increases in P ET , CO 2 of 5 and 10 Torr above baseline; and (ii) rebreathing-induced transient breath-by-breath increases in P ET , CO 2. The linear regression for CBFV versus P ET , CO 2 (P = 0.65) and CVCI versus P ET , CO 2 (P = 0.44) was similar between methods; however, individual variability in CBFV or CVCI responses existed among subjects. To address the second hypothesis, the same measurements were made during the following two conditions (randomized): (i) immediately following a brief period of hypocapnia induced by hyperventilation for 1 min followed by rebreathing; and (ii) during rebreathing only. The slope of the linear regression for CBFV versus P ET , CO 2 (P < 0.01) and CVCI versus P ET , CO 2 (P < 0.01) was reduced during hyperventilation plus rebreathing relative to rebreathing only. These results indicate that cerebral vasomotor reactivity to changes in P aCO 2 is similar regardless of the employed methodology to induce changes in P aCO 2 and that hyperventilation-induced hypocapnia attenuates the cerebral vasodilatory responses during a subsequent period of rebreathing

  8. VHTRC experiment for verification test of H∞ reactivity estimation method

    International Nuclear Information System (INIS)

    Fujii, Yoshio; Suzuki, Katsuo; Akino, Fujiyoshi; Yamane, Tsuyoshi; Fujisaki, Shingo; Takeuchi, Motoyoshi; Ono, Toshihiko

    1996-02-01

    This experiment was performed at VHTRC to acquire the data for verifying the H∞ reactivity estimation method. In this report, the experimental method, the measuring circuits and data processing softwares are described in details. (author)

  9. Experiment data report for LOFT anticipated transient without scram Experiment L9-4

    International Nuclear Information System (INIS)

    Batt, D.L.; Divine, J.M.; McKenna, K.J.

    1982-11-01

    Selected pertinent and uninterpreted data from the fourth anticipated transient with multiple failures experiment (Experiment L9-4) conducted on September 24, 1982, in the Loss-of-Fluid Test (LOFT) facility are presented. The LOFT facility is a 50-MW(t) pressurized water reactor (PWR) system with instruments that measure and provide data on the system's thermal-hydraulic and nuclear conditions. The operation of the LOFT system is typical of large [approx. 1000 MW(e)], commercial PWR operations. Experiment L9-4 simulated a loss-of-offsite-power anticipated transient without reactor scram. The loss-of-offsite-power accident led to an increase in the primary coolant system temperature and pressure. The experiment safety relief valve opened and was able to limit and control the pressure transient. In addition, subsequent heat generation was dissipated by the auxiliary feedwater flow in the secondary coolant system until the reactor was scrammed at experiment termination

  10. Experiment on transient heat transfer in closed narrow channel

    International Nuclear Information System (INIS)

    Ochiai, Masaaki

    1985-01-01

    Heat transfer coefficients and transient pressures in closed narrow channels were obtained experimentally, in order to assess the gap heat transfer models in the computer code WTRLGD which were devised to analyze the internal pressure behavior of waterlogged fuel rods. Gap widths of channels are 0.1--0.5mm to simulate the gap region of waterlogged fuel rods, and test fluids are water (7--89.2 0 C) and Freon-113 (9.2 0 C). The results show that the heater temperature and the pressure measured in the experiments without the DNB occurrence are simulated fairly well by the calculational model of WTRLGD where the heat transfer in a closed narrow channel is evaluated with one-dimensional transient thermal conduction equation and Jens and Lottes' correlation for nucleate boiling. Consequently, it is also suggested that the above equations are available for evaluation of heat flux from fuel to internal water of waterlogged fuel rods. The film boiling heat transfer coefficient was in the same order of that evaluated by Bromley's correlation and the DNB heat flux was smaller than that obtained in quasi-steady experiments with ordinary systems, although the experimental data for them were not enough. (author)

  11. Rapid and transient stimulation of intracellular reactive oxygen species by melatonin in normal and tumor leukocytes

    International Nuclear Information System (INIS)

    Radogna, Flavia; Paternoster, Laura; De Nicola, Milena; Cerella, Claudia; Ammendola, Sergio; Bedini, Annalida; Tarzia, Giorgio; Aquilano, Katia; Ciriolo, Maria; Ghibelli, Lina

    2009-01-01

    Melatonin is a modified tryptophan with potent biological activity, exerted by stimulation of specific plasma membrane (MT1/MT2) receptors, by lower affinity intracellular enzymatic targets (quinone reductase, calmodulin), or through its strong anti-oxidant ability. Scattered studies also report a perplexing pro-oxidant activity, showing that melatonin is able to stimulate production of intracellular reactive oxygen species (ROS). Here we show that on U937 human monocytes melatonin promotes intracellular ROS in a fast (< 1 min) and transient (up to 5-6 h) way. Melatonin equally elicits its pro-radical effect on a set of normal or tumor leukocytes; intriguingly, ROS production does not lead to oxidative stress, as shown by absence of protein carbonylation, maintenance of free thiols, preservation of viability and regular proliferation rate. ROS production is independent from MT1/MT2 receptor interaction, since a) requires micromolar (as opposed to nanomolar) doses of melatonin; b) is not contrasted by the specific MT1/MT2 antagonist luzindole; c) is not mimicked by a set of MT1/MT2 high affinity melatonin analogues. Instead, chlorpromazine, the calmodulin inhibitor shown to prevent melatonin-calmodulin interaction, also prevents melatonin pro-radical effect, suggesting that the low affinity binding to calmodulin (in the micromolar range) may promote ROS production.

  12. KIVA3, Transient Multicomponent 2-D and 3-D Reactive Flows with Fuel Sprays

    International Nuclear Information System (INIS)

    Amsden, A.A.

    2001-01-01

    1 - Description of program or function: KIVA3VRELEASE2 is a computer program for the numerical calculation of transient, two and three-dimensional, chemically reactive flows with sprays. It is a newer version of the earlier KIVA3 (1993) that has now been extended to model vertical of canted valves in the cylinder head of a gasoline or diesel engine. KIVA3, in turn, was based on the earlier KIVA2 (1989) and uses the same numerical solution procedure and solves the same sort of equations. KIVA3VRELEASE2 uses a block-structured mesh with connectivity defined through indirect addressing. The departure from a single rectangular structure in logical space allows complex geometries to be modeled with significantly greater efficiency because large regions of deactivated cells are no longer necessary. Cell-face boundary conditions permit greater flexibility and simplification in the application of boundary conditions. KIVA3VRELEASE2 contains a number of significant changes. New features enhance the robustness, efficiency, and usefulness of the overall program for engine modeling. Automatic restart of the cycle with a reduced time-step in case of iteration limit or temperature overflow will reduce code crashes. A new option provides automatic deactivation of a port region when it is closed from the cylinder and reactivation when it communicates with the cylinder. Corrections in the code improve accuracy; extensions to the particle-based liquid wall film model makes the model more complete and a spli injection option has been added. A new subroutine monitors the liquid and gaseous fuel phases and energy balance data and emissions are monitored and printed. New features have been added to the grid generator K3PREP and the graphics post processor, K3POST. 2 - Method of solution: KIVA3VRELEASE2 solves the unsteady equations of motion of a turbulent, chemically reactive mixture of ideal gases, coupled to the equations for a single-component vaporizing fuel spray. The gas

  13. Transient voltage control of a DFIG-based wind power plant for suppressing overvoltage using a reactive current reduction loop

    Directory of Open Access Journals (Sweden)

    Geon Park

    2016-01-01

    Full Text Available This paper proposes a transient voltage control scheme of a doubly fed induction generator (DFIG-based wind power plant (WPP using a reactive current reduction loop to suppress the overvoltage at a point of interconnection (POI and DFIG terminal after a fault clearance. The change of terminal voltage of a DFIG is monitored at every predefined time period to detect the fault clearance. If the voltage change exceeds a set value, then the reactive current reduction loop reduces the reactive current reference in the DFIG controller using the step function. The reactive current injection of DFIGs in a WPP is rapidly reduced, and a WPP can rapidly suppress the overvoltage at a fault clearance because the reactive current reference is reduced. Using an electromagnetic transients program–released version (EMTP–RV simulator, the performance of the proposed scheme was validated for a model system comprising 20 units of a 5-MW DFIG considering various scenarios, such as fault and wind conditions. Test results show that the proposed scheme enables a WPP to suppress the overvoltage at the POI and DFIG terminal within a short time under grid fault conditions.

  14. A review of experiments and results from the transient reactor test (TREAT) facility

    International Nuclear Information System (INIS)

    Deitrich, L. W.

    1998-01-01

    The TREAT Facility was designed and built in the late 1950s at Argonne National Laboratory to provide a transient reactor for safety experiments on samples of reactor fuels. It first operated in 1959. Throughout its history, experiments conducted in TREAT have been important in establishing the behavior of a wide variety of reactor fuel elements under conditions predicted to occur in reactor accidents ranging from mild off normal transients to hypothetical core disruptive accidents. For much of its history, TREAT was used primarily to test liquid-metal reactor fuel elements, initially for the Experimental Breeder Reactor-II (EBR-II), then for the Fast Flux Test Facility (FFTF), the Clinch River Breeder Reactor Plant (CRBRP), the British Prototype Fast Reactor (PFR), and finally, for the Integral Fast Reactor (IFR). Both oxide and metal elements were tested in dry capsules and in flowing sodium loops. The data obtained were instrumental in establishing the behavior of the fuel under off-normal and accident conditions, a necessary part of the safety analysis of the various reactors. In addition, TREAT was used to test light-water reactor (LWR) elements in a steam environment to obtain fission-product release data under meltdown conditions. Studies are now under way on applications of TREAT to testing of the behavior of high-burnup LWR elements under reactivity-initiated accident (RIA) conditions using a high-pressure water loop

  15. A FRAMEWORK FOR INTERPRETING FAST RADIO TRANSIENTS SEARCH EXPERIMENTS: APPLICATION TO THE V-FASTR EXPERIMENT

    International Nuclear Information System (INIS)

    Trott, Cathryn M.; Tingay, Steven J.; Wayth, Randall B.; Macquart, Jean-Pierre R.; Palaniswamy, Divya; Thompson, David R.; Wagstaff, Kiri L.; Majid, Walid A.; Burke-Spolaor, Sarah; Deller, Adam T.; Brisken, Walter F.

    2013-01-01

    We define a framework for determining constraints on the detection rate of fast transient events from a population of underlying sources, with a view to incorporate beam shape, frequency effects, scattering effects, and detection efficiency into the metric. We then demonstrate a method for combining independent data sets into a single event rate constraint diagram, using a probabilistic approach to the limits on parameter space. We apply this new framework to present the latest results from the V-FASTR experiment, a commensal fast transients search using the Very Long Baseline Array (VLBA). In the 20 cm band, V-FASTR now has the ability to probe the regions of parameter space of importance for the observed Lorimer and Keane fast radio transient candidates by combining the information from observations with differing bandwidths, and properly accounting for the source dispersion measure, VLBA antenna beam shape, experiment time sampling, and stochastic nature of events. We then apply the framework to combine the results of the V-FASTR and Allen Telescope Array Fly's Eye experiments, demonstrating their complementarity. Expectations for fast transients experiments for the SKA Phase I dish array are then computed, and the impact of large differential bandwidths is discussed.

  16. Transient Control of Synchronous Machine Active and Reactive Power in Micro-grid Power Systems

    Science.gov (United States)

    Weber, Luke G.

    There are two main topics associated with this dissertation. The first is to investigate phase-to-neutral fault current magnitude occurring in generators with multiple zero-sequence current sources. The second is to design, model, and tune a linear control system for operating a micro-grid in the event of a separation from the electric power system. In the former case, detailed generator, AC8B excitation system, and four-wire electric power system models are constructed. Where available, manufacturers data is used to validate the generator and exciter models. A gain-delay with frequency droop control is used to model an internal combustion engine and governor. The four wire system is connected through a transformer impedance to an infinite bus. Phase-to-neutral faults are imposed on the system, and fault magnitudes analyzed against three-phase faults to gauge their severity. In the latter case, a balanced three-phase system is assumed. The model structure from the former case - but using data for a different generator - is incorporated with a model for an energy storage device and a net load model to form a micro-grid. The primary control model for the energy storage device has a high level of detail, as does the energy storage device plant model in describing the LC filter and transformer. A gain-delay battery and inverter model is used at the front end. The net load model is intended to be the difference between renewable energy sources and load within a micro-grid system that has separated from the grid. Given the variability of both renewable generation and load, frequency and voltage stability are not guaranteed. This work is an attempt to model components of a proposed micro-grid system at the University of Wisconsin Milwaukee, and design, model, and tune a linear control system for operation in the event of a separation from the electric power system. The control module is responsible for management of frequency and active power, and voltage and reactive

  17. The VLA Low-band Ionosphere and Transient Experiment (VLITE)

    Science.gov (United States)

    Clarke, Tracy; Peters, Wendy; Brisken, Walter; Giacintucci, Simona; Kassim, Namir; Polisensky, Emil; Helmboldt, Joseph; Richards, Emily E.; Erickson, Alan; Ray, Paul S.; Kerr, Matthew T.; Deneva, Julia; Coburn, William; Huber, Robert; Long, Jeff

    2018-01-01

    The VLA Low-band Ionosphere and Transient Experiment (VLITE, http://vlite.nrao.edu/ ) is a commensal low-frequency observing system that has been operational on the National Radio Astronomy Observatory's Karl G. Jansky Very Large Array (VLA) since late 2014. The separate optical paths of the prime-focus sub-GHz dipole feeds and the Cassegrain-focus 1-50 GHz feeds allow both systems to operate simultaneously with independent correlators. The initial 2.5 years of VLITE operation provided real-time correlation of 10 antennas across the 320-384 MHz band with a total observing time approaching 12,000 hours. During the summer of 2017, VLITE was upgraded to a total of 16 antennas (more than doubling the number of baselines) with enhanced correlator capabilities to enable correlation of the on-the-fly observing mode being used for the new NRAO VLA Sky Survey (VLASS).We present an overview of the VLITE system, including highlights of the complexities of a commensal observing program, sparse-array challenges, and scientific capabilities from our science-ready data pipeline. In the longer term, we seek a path to broadband expansion across all VLA antennas to develop a powerful new LOw Band Observatory (LOBO).

  18. Experiment data report for LOFT anticipated transient-without-scram Experiment L9-3

    International Nuclear Information System (INIS)

    Bayless, P.D.; Divine, J.M.

    1982-05-01

    Selected pertinent and uninterpreted data from the third anticipated transient with multiple failures experiment (Experiment L9-3) conducted in the Loss-of-Fluid Test (LOFT) facility are presented. The LOFT facility is a 50-MW(t) pressurized water reactor (PWR) system with instruments that measure and provide data on the system thermal-hydraulic and nuclear conditions. The operation of the LOFT system is typical of large [approx. 1000 MW(e)], commercial PWR operations. Experiment L9-3 simulated a loss-of-feedwater anticipated transient without scram. The loss-of-feedwater accident led to an increase in the primary coolant system temperature and pressure. Both the experiment power-operated relief valve (PORV) and safety relief valve opened and were able to limit and control the pressure transient. The plant was then recovered with the control rods still withdrawn by injecting 7200-ppM borated water, manually cycling the PORV and feeding and bleeding the steam generator

  19. Transient groundwater chemistry near a river: Effects on U(VI) transport in laboratory column experiments

    Science.gov (United States)

    Yin, Jun; Haggerty, Roy; Stoliker, Deborah L.; Kent, Douglas B.; Istok, Jonathan D.; Greskowiak, Janek; Zachara, John M.

    2011-01-01

    In the 300 Area of a U(VI)-contaminated aquifer at Hanford, Washington, USA, inorganic carbon and major cations, which have large impacts on U(VI) transport, change on an hourly and seasonal basis near the Columbia River. Batch and column experiments were conducted to investigate the factors controlling U(VI) adsorption/desorption by changing chemical conditions over time. Low alkalinity and low Ca concentrations (Columbia River water) enhanced adsorption and reduced aqueous concentrations. Conversely, high alkalinity and high Ca concentrations (Hanford groundwater) reduced adsorption and increased aqueous concentrations of U(VI). An equilibrium surface complexation model calibrated using laboratory batch experiments accounted for the decrease in U(VI) adsorption observed with increasing (bi)carbonate concentrations and other aqueous chemical conditions. In the column experiment, alternating pulses of river and groundwater caused swings in aqueous U(VI) concentration. A multispecies multirate surface complexation reactive transport model simulated most of the major U(VI) changes in two column experiments. The modeling results also indicated that U(VI) transport in the studied sediment could be simulated by using a single kinetic rate without loss of accuracy in the simulations. Moreover, the capability of the model to predict U(VI) transport in Hanford groundwater under transient chemical conditions depends significantly on the knowledge of real-time change of local groundwater chemistry.

  20. Periodic transients linked to a variation in reactivity; Transitoires de periode lies a une variation de reactivite

    Energy Technology Data Exchange (ETDEWEB)

    Furet, J; Weil, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    We study here the influence of the transient, linked to a variation in reactivity, on the measurement of the period, this measurement being made from the logarithmic differential of the power and being defined by 1/T 1/p(dp/dt). We show that the adjustment of the thresholds of period safety is often incompatible with the velocities of liberation of reactivity. A compromise is then necessary between the speed of response of the periodimeter and the speed with which the reactivity is liberated. This makes it necessary to have rapid security devices for the power levels in the piles in which the speeds of liberation of the reactivity are high. (author) [French] On etudie ici l'influence du transitoire lie a une variation de la reactivite sur la mesure de la periode, cette mesure etant faite a partir de la derivee logarithmique de la puissance et etant definie par 1/T 1/p(dp/dt). On montre que le reglage des seuils de securite periode est souvent incompatible avec les vitesses de liberation de reactivite. Il y a alors un compromis a faire entre la vitesse de reponse du periodemetre et la vitesse de liberation de reactivite. Ceci impose de disposer de securites rapides sur les niveaux de puissance, dans les piles ou les vitesses de liberation de reactivite sont importantes. (auteur)

  1. Modelling Reactivity-Initiated-Accident Experiments With Falcon And SCANAIR: A Comparison Exercise

    International Nuclear Information System (INIS)

    Romano, A.; Wallin, H.; Zimmermann, M.A.

    2005-01-01

    A critical assessment is made of the state-of-the-art fuel performance code FALCON in the context of selected Reactivity Initiated Accident (RIA) experiments from the CABRI REP Na series, and contrasts its predictions against those of the extensively benchmarked SCANAIR (Version 3.2) code. The thermal fields in the fuel and cladding, the clad mechanical deformation, and the Fission Gas Release (FGR) are adopted as 'Figures of Merit' by which to judge code performance. Particular attention is paid to the importance of fission-gas-induced clad deformation (which is modelled in SCANAIR, but not in FALCON), relative to that driven by the fuel thermal expansion (which is modelled by both codes). The thermal fields calculated by the codes are in good agreement with each other, especially during the initial stages of the transients --- the adiabatic phase. Larger discrepancies are observed at later times, and are due to the different models applied to calculate the gap conductance. FALCON predicts clad permanent deformations at the end of the transients with a maximum deviation from the experimental measurements of about 20%. Generally, the code always tends to underpredict the measurements. SCANAIR performs similarly, but grossly overpredicts the permanent clad strain for the case involving a very energetic pulse. The fission-gas-driven clad deformation is only relevant for very fast pulse energy injection cases, which are not prototypical of the RIA transients expected in PWRs. The FGR models in FALCON do not capture the mechanism of 'burst-release' in the RIA transients, having been developed for steady-state irradiation conditions. This also explains why they performed poorly when applied to the fast-transient cases analyzed here. In contrast, the FGR results from SCANAIR are in satisfactory agreement with the experimental results. (author)

  2. RETRAN experience with BWR transients at Yankee Atomic Electric Company

    International Nuclear Information System (INIS)

    Ansari, A.A.F.; Cronin, J.T.; Slifer, B.C.

    1981-01-01

    Yankee Atomic Electric Company is actively involved in the development of licensing methods for BWR's. The computer code chosen for analyzing system response under transient conditions is RETRAN. This paper describes the RETRAN model developed for Vermont Yankee, and the results of the RETRAN checkout and qualification that has been achieved at YAEC through comparison of RETRAN predictions to the startup test results performed at the plant as part of the 100% power startup test program. In addition, abnormal operational transients typically analyzed for licensing are also presented

  3. Assessment of the TASS 1-D neutronics model for the westinghouse and ABB-CE type PWR reactivity induced transients

    International Nuclear Information System (INIS)

    Choi, J.D.; Yoon, H.Y.; Um, K.S.; Kim, H.C.; Sim, S.K.

    1997-01-01

    Best estimate transient analysis code, TASS, has been developed for the normal and transient simulation of the Westinghouse and ABB-CE type PWRs. TASS thermal hydraulic model is based on the non-homogeneous, non-equilibrium two-phase continuity, energy and mixture momentum equations with constitutive relations for closure. Core neutronics model employs both the point kinetics and one-dimensional neutron diffusion model. Semi-implicit numerical scheme is used to solve the discretized finite difference equations. TASS one dimensional neutronics core model has been assessed through the reactivity induced transient analyses for the KORI-3, three loop Westinghouse PWR, and Younggwang-3 (YGN-3), two-loop ABB-CE PWR, nuclear power plants currently operating in Korea. The assessment showed that the TASS one dimensional neutronics core model can be applied for the Westinghouse and ABB-CE type PWRs to gain thermal margin which is necessary for a potential use of the high fuel burnup, extended fuel cycle, power upgrading and for the plant life extension

  4. Classification of transient processes with a jumplike change in the reactivity

    International Nuclear Information System (INIS)

    Sabaeva, T.A.

    1989-01-01

    The problem of the change in the neutron flux density accompanying a jumplike (instantaneous) change in the reactivity is classical and is studied in most textbooks and monographs devoted to the regulation of nuclear reactors, where in constructing the response only the feedback on delayed neutrons is taken into account. The use of a linear feedback of a general form permits describing reactors of different types. A classification of feedbacks on reactivity was presented by Sabaeva, where a parabolic region in phase space is separated. A peak in the neutron flux corresponds to the image point falling into this region. In this paper the conditions making it possible to find the change in the neutrons flux immediately after an instantaneous change in the reactivity are derived, and the feedbacks are classified based on this

  5. Proceedings of the OECD/CSNI specialists meeting on boron dilution reactivity transients

    International Nuclear Information System (INIS)

    1997-06-01

    The purpose of the meeting was to bring together experts involved in the different activities related to boron dilution transients. The experts came from all involved parties, including research organizations, regulatory authorities, vendors and utilities. Information was openly shared and discussed on the experimental results, plant and systems analysis, numerical analysis of mixing and probability and consequences of these transients. Regulatory background and licensing implications were also included to provide the proper frame work for the technical discussion. Each of these areas corresponded to a separate session. The meeting focused on the thermal-hydraulic aspects because of the current interest in that subject and the significant amount of new technical information being generated

  6. Guanosine radical reactivity explored by pulse radiolysis coupled with transient electrochemistry.

    Science.gov (United States)

    Latus, A; Alam, M S; Mostafavi, M; Marignier, J-L; Maisonhaute, E

    2015-06-04

    We follow the reactivity of a guanosine radical created by a radiolytic electron pulse both by spectroscopic and electrochemical methods. This original approach allows us to demonstrate that there is a competition between oxidation and reduction of these intermediates, an important result to further analyse the degradation or repair pathways of DNA bases.

  7. Analyses of criticality and reactivity for TRACY experiments based on JENDL-3.3 data library

    International Nuclear Information System (INIS)

    Sono, Hiroki; Miyoshi, Yoshinori; Nakajima, Ken

    2003-01-01

    The parameters on criticality and reactivity employed for computational simulations of the TRACY supercritical experiments were analyzed using a recently revised nuclear data library, JENDL-3.3. The parameters based on the JENDL-3.3 library were compared to those based on two former-used libraries, JENDL-3.2 and ENDF/B-VI. In the analyses computational codes, MVP, MCNP version 4C and TWOTRAN, were used. The following conclusions were obtained from the analyses: (1) The computational biases of the effective neutron multiplication factor attributable to the nuclear data libraries and to the computational codes do not depend the TRACY experimental conditions such as fuel conditions. (2) The fractional discrepancies in the kinetic parameters and coefficients of reactivity are within ∼5% between the three libraries. By comparison between calculations and measurements of the parameters, the JENDL-3.3 library is expected to give closer values to the measurements than the JENDL-3.2 and ENDF/B-VI libraries. (3) While the reactivity worth of transient rods expressed in the $ unit shows ∼5% discrepancy between the three libraries according to their respective β eff values, there is little discrepancy in that expressed in the Δk/k unit. (author)

  8. Transient splenial lesion: Further experience with two cases

    International Nuclear Information System (INIS)

    Singh, Paramjeet; Gogoi, Dhrubajyoti; Vyas, Sameer; Khandelwal, Niranjan

    2010-01-01

    Transient splenial lesions (TSL) of the corpus callosum are uncommon radiologic findings that are seen in a number of clinical conditions with varied etiologies. They were first described a decade earlier in patients with epilepsy and hence were thought to be seizure or seizure therapy related. Subsequently, more cases were described by different observers in diseases with different etiologies, and the list is still increasing. Awareness of these lesions is necessary as they are an uncommon finding and have to be differentiated from other infective/noninfective causes. MRI is the imaging modality of choice as these lesions are not seen on routine noncontrast CT scan. The authors here describe two cases which showed TSL, with complete/partial resolution on follow-up scans. The authors also present a review of the literature

  9. Transient splenial lesion: Further experience with two cases

    Directory of Open Access Journals (Sweden)

    Singh Paramjeet

    2010-01-01

    Full Text Available Transient splenial lesions (TSL of the corpus callosum are uncommon radiologic findings that are seen in a number of clinical conditions with varied etiologies. They were first described a decade earlier in patients with epilepsy and hence were thought to be seizure or seizure therapy related. Subsequently, more cases were described by different observers in diseases with different etiologies, and the list is still increasing. Awareness of these lesions is necessary as they are an uncommon finding and have to be differentiated from other infective/noninfective causes. MRI is the imaging modality of choice as these lesions are not seen on routine noncontrast CT scan. The authors here describe two cases which showed TSL, with complete/partial resolution on follow-up scans. The authors also present a review of the literature.

  10. Transient behavior during reactivity insertion in the Moroccan TRIGA Mark II reactor using the PARET/ANL code

    International Nuclear Information System (INIS)

    Boulaich, Y.; Nacir, B.; El Bardouni, T.; Boukhal, H.; Chakir, E.; El Bakkari, B.; El Younoussi, C.

    2015-01-01

    Highlights: • PARET model for the Moroccan TRIGA MARK II reactor has been developed. • Transient behavior under reactivity insertion has been studied based on PARET code. • Power factors required by PARET code have been calculated by using MCNP5 code. • The dependence on time of the main thermal-hydraulic parameters was calculated. • Results are largely far to compromise the thermal design limits. - Abstract: A three dimensional model for the Moroccan 2 MW TRIGA MARK II reactor has been developed for thermal-hydraulic and safety analysis by using the PARET/ANL and MCNP5 codes. This reactor is located at the nuclear studies center of Mâamora (CENM), Morocco. The model has been validated through temperature measurements inside two instrumented fuel elements located near the center of the core, at various power levels, and also through the power and fuel temperature evolution after the reactor shutdown (SCRAM). The axial distributions of power factors required by the PARET code have been calculated in each fuel element rod by using MCNP5 code. Based on this thermal-hydraulic model, a safety analysis under the reactivity insertion phenomenon has been carried out and the dependence on time of the main thermal-hydraulic parameters was calculated. Results were compared to the thermal design limits imposed to maintain the integrity of the clad

  11. CYLFUX, Fast Reactor Reactivity Transients Simulation in LWR by 2-D 2 Group Diffusion

    International Nuclear Information System (INIS)

    Schmidt, A.

    1973-01-01

    1 - Nature of physical problem solved: A 2-dimensional calculation of the 2-group, space-dependent neutron diffusion equations is performed in r-z geometry using an arbitrary number of groups of delayed neutron precursors. The program is designed to simulate fast reactivity excursions in light water reactors taking into account Doppler feedback via adiabatic heatup of fuel. Axial motions of control rods may be considered including scram action on option. 2 - Method of solution: The differential equations are solved at each time step by an explicit finite difference method using two time levels. The stationary distributions are obtained by using the same algorithm. 3 - Restrictions on the complexity of the problem: No restriction to the number of space points and delayed neutron energy groups besides the computer size

  12. Integrated, digital experiment transient control and safety protection of an in-pile test

    International Nuclear Information System (INIS)

    Thomas, R.W.; Whitacre, R.F.; Klingler, W.B.

    1982-01-01

    The Sodium Loop Safety Facility experimental program has demonstrated that in-pile loop fuel failure transient tests can be digitally controlled and protected with reliability and precision. This was done in four nuclear experiments conducted in the Engineering Test Reactor operated by EG and G Idaho, Inc., at the Idaho National Engineering Laboratory. Loop sodium flow and reactor power transients can be programmed to sponsor requirements and verified prior to the test. Each controller has redundancy, which reduces the effect of single failures occurring during test transients. Feedback and reject criteria are included in the reactor power control. Timed sequencing integrates the initiation of the controllers, programmed safety set-points, and other experiment actions (e.g., planned scram). Off-line and on-line testing is included. Loss-of-flow, loss-of-piping-integrity, boiling-window, transient-overpower, and local fault tests have been successfully run using this system

  13. Final report for the H3 transient overpower failure threshold experiment

    International Nuclear Information System (INIS)

    Wright, A.E.; Rothman, A.B.; Stahl, D.; Agrawal, A.K.; Deitrich, L.W.; Chen, S.S.

    1975-06-01

    Test H3 was the first transient overpower failure-threshold experiment in TREAT to use irradiated fuel and to employ a TREAT transient shaped to produce sample-temperature distributions typical of steady state prior to the overpower excursion. A seven-pin assembly was tested within the Mark-II TREAT sodium loop. The experiment was performed successfully with satisfactory TREAT power transient and loop performance, and demonstrated the capability of intermediate-power EBR-II-irradiated fuel at low burnup (no central void) to withstand a mild overpower transient that terminated with fuel temperatures just short of the solidus without cladding strain. Calculated values of outlet coolant temperature and amount of molten fuel generally agree well with the test data. Posttest thermalhydraulic and mechanical analyses of the fuel pins are reported. Results of detailed nondestructive and destructive examinations of the preirradiated central pin and a fresh peripheral pin are presented. (U.S.)

  14. CO2 injection into fractured peridotites: a reactive percolation experiment

    Science.gov (United States)

    Escario, S.; Godard, M.; Gouze, P.; Leprovost, R.; Luquot, L.; Garcia-Rios, M.

    2017-12-01

    Mantle peridotites have the potential to trap CO2 as carbonates. This process observed in ophiolites and in oceanic environments provides a long term and safe storage for CO2. It occurs as a part of a complex suite of fluid-rock reactions involving silicate dissolution and precipitation of hydrous phases, carbonates and minor phases that may in turn modify the hydrodynamic properties and the reactivity of the reacted rocks. The efficiency and lastingness of the process require the renewal of fluids at the mineral-fluid interface. Fractures are dominant flow paths in exhumed mantle sections. This study aims at better understanding the effect of CO2-enriched saline fluids on hydrodynamic and chemical processes through fractured peridotites. Experiments were performed using the reactive percolation bench ICARE Lab 3 - Géosciences Montpellier. It allows monitoring the permeability changes during experiments. Effluents are recurrently sampled for analysing cation concentration, pH and alkalinity. Reacted rock samples were characterized by high resolution X-ray microtomography (ESRF ID19, Grenoble, France) and SEM. Experiments consisted in injecting CO2-enriched brines (NaCl 0.5 M) at a rate of 6 mL.h-1 into artificially fractured cores (9 mm diameter × 20 mm length) of Oman harzburgites at T=170°C and Ptotal = 25 MPa for up to 2 weeks. Fractures are of few µm apertures with rough walls. Three sets of experiments were performed at increasing value of [CO2] (0, 0.1 and 1 mol/kg). All experiments showed a decrease in permeability followed by steady state regime that can be caused by a decrease in the roughness of fracture walls (dissolution dominated process), thus favouring fracture closing, or by the precipitation of secondary phases. Maximum enrichments in Mg, Fe and Ca of the effluent fluids occur during the first 2 hours of the experiments whereas Si displays a maximum enrichment at t = 20 h, suggesting extensive dissolution. Maximum enrichments are observed with

  15. Reactivity feedback evaluation of material relocations in the CABRI-1 experiments with fuel worth distributions from SNR-300

    International Nuclear Information System (INIS)

    Royl, P.; Pfrang, W.; Struwe, D.

    1991-01-01

    The fuel relocations from the CABRI-1 experiments with irradiated fuel that had been evaluated from the hodoscope measurements were used together with fuel reactivity worth distributions from the SNR-300 to estimate the reactivity effect which these motions would have if they occurred in SNR-300 at the same relative distance to the peak power as in CABRI. The procedure for the reactivity evaluation is outlined including the assumptions made for fuel mass conservation. The results show that the initial fuel motion yields always negative reactivities. They also document the mechanism for a temporary reactivity increase by in-pin fuel flow in some transient overpower tests. This mechanism, however, never dominates, because material accumulates always sufficiently above the peak power point. Thus, the late autocatalytic amplifications of voiding induced power excursions by compactive in-pin fuel flow, that had been simulated in bounding loss of flow analyses for SNR-300, have no basis at all when considering the results from the CABRI-1 experiments

  16. SPECT study of cerebral blood flow reactivity after acetazolamide in patients with transient ischemic attacks

    International Nuclear Information System (INIS)

    Chollet, F.; Celsis, P.; Clanet, M.; Guiraud-Chaumeil, B.; Rascol, A.; Marc-Vergnes, J.P.

    1989-01-01

    We investigated 15 patients with one or more transient ischemic attacks (TIAs) in the internal carotid artery territory within the month following the most recent TIA. Cerebral blood flow (CBF) was measured by single-photon emission computed tomography, using intravenous xenon-133 before and after injection of 1 g acetazolamide. Six patients had severe carotid stenosis or occlusion; the other nine patients had no significant carotid lesions. Twenty age-matched volunteers free of neurologic symptoms or history were used as controls. Mean CBF in the sylvian region was not significantly different between patients and controls. Seven patients exhibited a focal hypoperfusion at rest in the symptomatic hemisphere, and their hypoperfused areas were hyporeactive after administration of acetazolamide. Seven other patients exhibited hyporeactive areas after acetazolamide administration while their CBF tomograms at rest were normal. Thus, CBF abnormalities were detected in 14 of the 15 patients. Our findings suggest that CBF measured early after acetazolamide administration could be useful to confirm the clinical diagnosis of TIA. In the nine patients with no significant lesion of the internal carotid artery, the areas of hypoperfusion were small and were probably related to the focal ischemic event. In the six patients with severe lesions of the internal carotid artery, abnormalities were of variable size and intensity but were often large and pronounced. The discrepancy between these two subgroups of patients could be ascribed to the hemodynamic influence of the internal carotid artery lesions. Moreover, our findings may provide some insight into the pathophysiology of TIAs

  17. SPLOSH III. A code for calculating reactivity and flow transients in CSGHWR

    International Nuclear Information System (INIS)

    Halsall, M.J.; Course, A.F.; Sidell, J.

    1979-09-01

    SPLOSH is a time dependent, one dimensional, finite difference (in time and space) coupled neutron kinetics and thermal hydraulics code for studying pressurised faults and control transients in water reactor systems. An axial single channel model with equally spaced mesh intervals is used to represent the neutronics of the reactor core. A radial finite difference model is used for heat conduction through the fuel pin, gas gap and can. Appropriate convective, boiling or post-dryout heat transfer correlations are used at the can-coolant interface. The hydraulics model includes the important features of the SGHWR primary loop including 'slave' channels in parallel with the 'mean' channel. Standard mass, energy and momentum equations are solved explicitly. Circuit features modelled include pumps, spray cooling and the SGHWR steam drum. Perturbations to almost any feature of the circuit model may be specified by the user although blowdown calculations resulting in critical or reversed flows are not permitted. Automatic reactor trips may be defined and the ensuing actions of moderator dumping and rod firing can be specified. (UK)

  18. COMEDIE BD1 experiment: Fission product behaviour during depressurization transients

    International Nuclear Information System (INIS)

    Gillet, R.; Brenet, D.; Hanson, D.L.; Kimball, O.F.

    1996-01-01

    An experimental program in the CEA COMEDIE loop has been carried out to obtain integral test data to validate the methods and transport models used to predict fission product release from the core and plate-out in the primary coolant circuit of the Modular High Temperature Gas Cooled Reactor (MHTGR) during normal operation and liftoff, and during rapid depressurization transients. The loop consists of an in-pile section with the fuel element, deposition section (heat exchanger), filters for collecting condensible Fission Productions (FP) during depressurization tests and an out-of-pile section devoted to chemical composition control of the gas and on-line analysis of gaseous FP. After steady state irradiation, the loop was subjected to a series of in-situ blowdowns at shear ratios (ratio of the wall shear stress during blowdown to that during steady state operation) ranging from 0.7 to 5.6. The results regarding the FP profiles on the plate-out section, before and after blowdowns are given. It appears that: the plate-out profiles depend on the FP chemistry; the depressurization phases have led to significant desorption of I 131, but on the contrary, they have almost no effect for the other FP such as Ag 110m, Cs 134, Cs 137 and Te 132. (author). 1 ref., 15 figs

  19. Experience in plant transients. The Swedish RKS program

    International Nuclear Information System (INIS)

    Bento, J.P.

    1983-09-01

    A data-base for reactor operation experience is presented. The input comes from utilities in 14 countries. From experience with the Swedish reactors, trends have been extracted. Using the number of operational scrams as a measure of reactor management, there seem to be a maximum at early reactor life, followed by a decreasing trend after 2 years. This seems to be true for all reactors in the programme. There is even a decrease in the number of scrams with further reactor generations. Causes for events and for scrams are evaluated. (Aa)

  20. Reactive transport modeling of the ABM experiment with Comsol Multiphysics

    International Nuclear Information System (INIS)

    Pekala, Marek; Idiart, Andres; Arcos, David

    2012-01-01

    Document available in extended abstract form only. The Swedish Organisation for Radioactive Waste Disposal (SKB) is considering disposal of the High Level Waste in a deep underground repository in a crystalline rock. According to the disposal concept, bentonite clay will be used in the near-field of the waste packages as buffer material. From solute transport point of view, the bentonite buffer is expected to provide a favourable environment, where radionuclide migration would be limited to slow diffusion and further retarded by sorption. In the KBS-3 repository design, the MX-80 bentonite is the reference buffer material. However, SKB has also been investigating alternative buffer materials. To this end, the field experiment Alternative Buffer Materials (ABM) was started at the Aespoe URL in 2006. Three packages of eleven different compacted bentonite blocks in different configurations have been tested over varying time scales. The packages with outer diameter of 0.28 m were deposited into 3 meter deep boreholes. After installation, packages were saturated and heated differently to target values. This contribution concerns the evolution of Package 1, which was initiated in December 2006 and ran for about 2.5 years. Post-mortem examination after retrieval showed that the initially contrasting chloride concentrations and cation-exchanger compositions between different bentonite blocks became significantly homogenised. It is thought that this behaviour could be explained as a first approximation by diffusion of major ions between the bentonite blocks coupled with cation-exchange. In this work, a modelling study to verify this hypothesis has been undertaken. In addition, the feasibility of implementing a reactive transport model into the Finite Element code COMSOL Multiphysics has been tested. The model considers a two-dimensional axisymmetric geometry of the depositional borehole, and includes coupled diffusion and cation-exchange of Na, K, Ca and Mg (as a chloride

  1. Reassessment of the basis for NRC fuel damage criteria for reactivity transients

    International Nuclear Information System (INIS)

    McCardell, R.K.

    1994-01-01

    The present basis for NRC Fuel Damage Criteria was obtained from experiments performed in the Special Power Excursion Reactor Test (SPERT) IV Reactor Capsule Driver Core (CDC) at the Idaho National Engineering Laboratory (INEL) between 1967 and 1970. Most of the CDC test fuel rods were previously unirradiated and the failure threshold for these unirradiated fuel rods was measured to be about 200 calories per gram of UO 2 radially averaged fuel enthalpy at the axial peak

  2. Targets with thin ferromagnetic layers for transient field experiments

    International Nuclear Information System (INIS)

    Gallant, J.L.; Dmytrenko, P.

    1982-01-01

    Multilayer targets containing a central layer sufficiently thin so that all recoil nuclei can traverse it and subsequently stop in a suitable cubic environment have been prepared. Such targets are required in experiments making use of a magnetic field acting on an ion moving through a ferromagnetic material. The preparation and annealing of the ferromagnetic foils (iron and gadolinium) and the fabrication of the multilayer targets are described. (orig.)

  3. Development of neutronics and thermal hydraulics coupled code – SAC-RIT for plate type fuel and its application to reactivity initiated transient analysis

    International Nuclear Information System (INIS)

    Singh, Tej; Kumar, Jainendra; Mazumdar, Tanay; Raina, V.K.

    2013-01-01

    Highlights: • A point reactor kinetics code coupled with thermal hydraulics of plate type fuel is developed. • This code is applicable for two phase flow of coolant. • Safety analysis of IAEA benchmark reactor core is carried out. • Results agree well with the results available in literature. - Abstract: A point reactor kinetics code SAC-RIT, acronym of Safety Analysis Code for Reactivity Initiated Transient, coupled with thermal hydraulics of two phase coolant flow for plate type fuel, is developed to calculate reactivity initiated transient analysis of nuclear research and test reactors. Point kinetics equations are solved by fourth order Runge Kutta method. Reactivity feedback effect is included into the code. Solution of kinetics equations gives neutronic power and it is then fed into a thermal hydraulic code where mass, momentum and thermal energy conservation equations are solved by explicit finite difference method to find out fuel, clad and coolant temperatures during transients. In this code, all possible flow regimes including laminar flow, transient flow and turbulent flow have been covered. Various heat transfer coefficients suitable for single liquid, sub-cooled boiling, saturation boiling, film boiling and single vapor phases are incorporated in the thermal hydraulic code

  4. French experience in transient data collection and fatigue monitoring of PWR's nuclear steam supply system

    International Nuclear Information System (INIS)

    Sabaton, M.; Morilhat, P.; Savoldelli, D.; Genette, P.

    1995-10-01

    Electricite de France (EDF), the french national electricity company, is operating 54 standardized pressurizer water reactors. This about 500 reactor-years experience in nuclear stations operation and maintenance area has allowed EDF to develop its own strategy for monitoring of age-related degradations of NPP systems and components relevant for plant safety and reliability. After more than fifteen years of experience in regulatory transient data collection and seven years of successful fatigue monitoring prototypes experimentation, EDF decided to design a new system called SYSFAC (acronym for SYsteme de Surveillance en FAtigue de la Chaudiere) devoted to transient logging and thermal fatigue monitoring of the reactor coolant pressure boundary. The system is fully automatic and directly connected to the on-site data acquisition network without any complementary instrumentation. A functional transient detection module and a mechanical transient detection module are in charge of the general transient data collection. A fatigue monitoring module is aimed towards a precise surveillance of five specific zones particularly sensible to thermal fatigue. After the first step of preliminary studies, the industrial phase of the SYSFAC project is currently going on, with hardware and software tests and implementation. The first SYSFAC system will be delivered to the pilot power plant by the beginning of 1996. The extension to all EDF's nuclear 900 MW is planned after one more year of feedback experience. (authors). 12 refs., 3 figs

  5. ITER transient consequences for material damage: modelling versus experiments

    International Nuclear Information System (INIS)

    Bazylev, B; Janeschitz, G; Landman, I; Pestchanyi, S; Loarte, A; Federici, G; Merola, M; Linke, J; Zhitlukhin, A; Podkovyrov, V; Klimov, N; Safronov, V

    2007-01-01

    Carbon-fibre composite (CFC) and tungsten macrobrush armours are foreseen as PFC for the ITER divertor. In ITER the main mechanisms of metallic armour damage remain surface melting and melt motion erosion. In the case of CFC armour, due to rather different heat conductivities of CFC fibres a noticeable erosion of the PAN bundles may occur at rather small heat loads. Experiments carried out in the plasma gun facilities QSPA-T for the ITER like edge localized mode (ELM) heat load also demonstrated significant erosion of the frontal and lateral brush edges. Numerical simulations of the CFC and tungsten (W) macrobrush target damage accounting for the heat loads at the face and lateral brush edges were carried out for QSPA-T conditions using the three-dimensional (3D) code PHEMOBRID. The modelling results of CFC damage are in a good qualitative and quantitative agreement with the experiments. Estimation of the droplet splashing caused by the Kelvin-Helmholtz (KH) instability was performed

  6. Coupling of 3-D core computational codes and a reactor simulation software for the computation of PWR reactivity accidents induced by thermal-hydraulic transients

    International Nuclear Information System (INIS)

    Raymond, P.; Caruge, D.; Paik, H.J.

    1994-01-01

    The French CEA has recently developed a set of new computer codes for reactor physics computations called the Saphir system which includes CRONOS-2, a three-dimensional neutronic code, FLICA-4, a three-dimensional core thermal hydraulic code, and FLICA-S, a primary loops thermal-hydraulic transient computation code, which are coupled and applied to analyze a severe reactivity accident induced by a thermal hydraulic transient: the Steamline Break accident for a pressurized water reactor until soluble boron begins to accumulate in the core. The coupling of these codes has proved to be numerically stable. 15 figs., 7 refs

  7. Transient Transport Experiments in the CDX-U Spherical Torus

    International Nuclear Information System (INIS)

    T. Munsat; P.C. Efthimion; B. Jones; R. Kaita; R. Majeski; D. Stutman; G. Taylor

    2001-01-01

    Electron transport has been measured in the Current Drive Experiment-Upgrade (CDX-U) using two separate perturbative techniques. Gas modulation at the plasma edge was used to introduce cold-pulses which propagate towards the plasma center, providing time-of-flight information leading to a determination of chi(subscript e) as a function of radius. Sawteeth at the q=1 radius (r/a ∼ 0.15) induced heat-pulses which propagated outward towards the plasma edge, providing a complementary time-of-flight based chi(subscript e) profile measurement. This work represents the first localized measurement of chi(subscript e) in a spherical torus. It is found that chi(subscript e) = 1-2 meters squared per second in the plasma core (r/a < 1/3), increasing by an order of magnitude or more outside of this region. Furthermore, the chi(subscript e) profile exhibits a sharp transition near r/a = 1/3. Spectral and profile analyses of the soft X-rays, scanning interferometer, and edge probe data show no evidence of a significant magnetic island causing the high chi(subscript e) region

  8. What is our experience in plant transients telling us

    International Nuclear Information System (INIS)

    Rosen, S.L.

    1984-01-01

    This chapter discusses some aspects of the Significant Event Evaluation and Information Network (SEE-IN program), some general findings that pertain to nuclear plant trips and scrams, and some of the things that have been learned while managing the SEE-IN program. SEE-IN provides a system for the identification of significant operating events and generic problems or root causes, which are reported to the entire nuclear industry in a timely manner. The main purpose of SEE-IN is to reduce the number and severity of plant incidents. The fact that there were only four events in 1980, one in 1981, one in 1982, and one in 1983 indicates a trend toward a reduction in the number of major incidents at operating nuclear plants in the US. It is concluded that if the trend continues and the frequency of events is spread out further in the future, it will confirm that the industry's systematic method of evaluating plant experience and taking corrective actions to avoid problems is reducing the number of major events

  9. The assessment of RELAP5/MOD2 based on pressurizer transient experiments

    International Nuclear Information System (INIS)

    Xue Hanjun; Tanrikut, A.; Menzel, R.

    1992-03-01

    Two typical experiments have been performed in Chinese test facility under full pressure load corresponding to typical PWRs, 1) dynamic behavior of pressurizer due to relief valve operations (Case-I) is extremely important in transients and accident conditions regarding depressurization of PWR primary system; 2) Outsurge/Insurge operation is one of the transient which is often encountered and experienced in pressurizer systems due to pressure transients in primary system of PWRs. The simulation capability of RELAP5/MOD2 is good in comparison to experimental results. The physical models (such as interface model, stratification model), playing a major role in such simulation, seems to be realistic. The effect of realistic valve modeling in depressurization simulation is extremely important. Sufficient data for relief valve (the dynamic characteristics of valve) play a major role. The time dependent junction model and the trip valve model with a reduced discharge coefficient of 0.2 give better predictions in agreement with the experiment data while the trip valve models with discharge coefficient 1.0 yield overdepressurization. The simulation of outsurge/insurge transient yields satisfactory results. The thermal non-equilibrium model is important with respect to simulation of complicated physical phenomena in outsurge/insurge transient but has a negligible effect upon the depressurization simulation. (orig./HP)

  10. The integrated circuit IC EMP transient state disturbance effect experiment method investigates

    International Nuclear Information System (INIS)

    Li Xiaowei

    2004-01-01

    Transient state disturbance characteristic study on the integrated circuit, IC, need from its coupling path outset. Through cable (aerial) coupling, EMP converts to an pulse current voltage and results in the impact to the integrated circuit I/O orifice passing the cable. Aiming at the armament system construction feature, EMP effect to the integrated circuit, IC inside the system is analyzed. The integrated circuit, IC EMP effect experiment current injection method is investigated and a few experiments method is given. (authors)

  11. Summary and evaluation of fuel dynamics transient-overpower experiments: status 1974

    International Nuclear Information System (INIS)

    Deitrich, L.W.; Doerner, R.C.; Hughes, T.H.; Wright, A.E.

    1977-06-01

    The report summarizes and evaluates experiments conducted in the Transient Reactor Test Facility (TREAT) using the Mark-II loop facility. The tests discussed are of the E and H series. Detailed descriptions of test conditions and test results as of February 1974 are presented. Since all data have not been acquired on all experiments, this report must be considered interim in nature. Particular emphasis is placed on data relevant to Fast Test Reactor (FTR) safety-analysis efforts

  12. Development of real time visual evaluation system for sodium transient thermohydraulic experiments

    International Nuclear Information System (INIS)

    Tanigawa, Shingo

    1990-01-01

    A real time visual evaluation system, the Liquid Metal Visual Evaluation System (LIVES), has been developed for the Plant Dynamics Test Loop facility at O-arai Engineering Center. This facility is designed to provide sodium transient thermohydraulic experimental data not only in a fuel subassembly but also in a plant wide system simulating abnormal or accident conditions in liquid metal fast breeder reactors. Since liquid metal sodium is invisible, measurements to obtain experimental data are mainly conducted by numerous thermo couples installed at various locations in the test sections and the facility. The transient thermohydraulic phenomena are a result of complicated interactions among global and local scale three-dimensional phenomena, and short- and long-time scale phenomena. It is, therefore, difficult to grasp intuitively thermohydraulic behaviors and to observe accurately both temperature distribution and flow condition solely by digital data or various types of analog data in evaluating the experimental results. For effectively conducting sodium transient experiments and for making it possible to observe exactly thermohydraulic phenomena, the real time visualization technique for transient thermohydraulics has been developed using the latest Engineering Work Station. The system makes it possible to observe and compare instantly the experiment and analytical results while experiment or analysis is in progress. The results are shown by not only the time trend curves but also the graphic animations. This paper shows an outline of the system and sample applications of the system. (author)

  13. Altered Brain Reactivity to Game Cues After Gaming Experience.

    Science.gov (United States)

    Ahn, Hyeon Min; Chung, Hwan Jun; Kim, Sang Hee

    2015-08-01

    Individuals who play Internet games excessively show elevated brain reactivity to game-related cues. This study attempted to test whether this elevated cue reactivity observed in game players is a result of repeated exposure to Internet games. Healthy young adults without a history of excessively playing Internet games were recruited, and they were instructed to play an online Internet game for 2 hours/day for five consecutive weekdays. Two control groups were used: the drama group, which viewed a fantasy TV drama, and the no-exposure group, which received no systematic exposure. All participants performed a cue reactivity task with game, drama, and neutral cues in the brain scanner, both before and after the exposure sessions. The game group showed an increased reactivity to game cues in the right ventrolateral prefrontal cortex (VLPFC). The degree of VLPFC activation increase was positively correlated with the self-reported increase in desire for the game. The drama group showed an increased cue reactivity in response to the presentation of drama cues in the caudate, posterior cingulate, and precuneus. The results indicate that exposure to either Internet games or TV dramas elevates the reactivity to visual cues associated with the particular exposure. The exact elevation patterns, however, appear to differ depending on the type of media experienced. How changes in each of the regions contribute to the progression to pathological craving warrants a future longitudinal study.

  14. New developments in French transient monitoring system: SYSFAC From the experiments to the industrial process

    Energy Technology Data Exchange (ETDEWEB)

    Balley, J. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; Bertagnolio, D. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; Faidy, C. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; Kappler, F. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; Kergoat, M. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; L`Huby, Y. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; Genette, P. [Electricite de France, 69 - Villeurbanne (France). SEPTEN; Savoldelli, D. [Electricite de France, Production-Transport DMAINT, 13 Esplanade Charles de Gaulle, 92060 La Defense (France); Fournier, I. [Electricite de France, Direction Etudes et Recherches REME, 25 allee privee, Carrefour Pleyel, 93206 St. Denis (France)

    1995-01-01

    After more than 15 years of experience with regulatory transient data collection, Electricite de France decided to design a new concept of fatigue monitoring system called SYSFAC. This new system is the result of seven years of successful experimentation with fatigue meters. This system will be connected to the on-site data acquisition system without any complementary instrumentation. The SYSFAC system has a modular structure: the mechanical transient module, the functional transient module, the fatigue meters module and the global damage computing module all have a high level of flexibility to be applied to various types of circuits. After the preliminary studies had been achieved, it was decided to undertake the industrial phase of the SYSFAC project. Specific codes on PC computers have been used to validate the basic concepts and the operator interface. Real-size coding will last one year and the first SYSFAC system will be delivered to the pilot power plant by the end of 1995. ((orig.)).

  15. New developments in French transient monitoring system: SYSFAC From the experiments to the industrial process

    International Nuclear Information System (INIS)

    Balley, J.; Fournier, I.

    1995-01-01

    After more than 15 years of experience with regulatory transient data collection, Electricite de France decided to design a new concept of fatigue monitoring system called SYSFAC. This new system is the result of seven years of successful experimentation with fatigue meters. This system will be connected to the on-site data acquisition system without any complementary instrumentation. The SYSFAC system has a modular structure: the mechanical transient module, the functional transient module, the fatigue meters module and the global damage computing module all have a high level of flexibility to be applied to various types of circuits. After the preliminary studies had been achieved, it was decided to undertake the industrial phase of the SYSFAC project. Specific codes on PC computers have been used to validate the basic concepts and the operator interface. Real-size coding will last one year and the first SYSFAC system will be delivered to the pilot power plant by the end of 1995. ((orig.))

  16. HEDL W-1 SLSF experiment LOPI transient and boiling test results

    International Nuclear Information System (INIS)

    Henderson, J.M.; Wood, S.A.; Rothrock, R.B.

    1980-01-01

    The W-1 Sodium Loop Safety Facility (SLSF) experiment was designed to study the heat release characteristics of fast reactor fuel pins under Loss-of-Piping-Integrity (LOPI) accident conditions and determine stable sodium boiling initiation and recovery limits in a prototypic fuel pin bundle array. The results of the experiment address major second level of assurance (LOA-2) safety issues and provide increased insight and understanding of phenomena that would inherently terminate hypothesized accidents with only limited core damage. The irradiation phase of the experiment, consisting of thirteen individual transients, was performed between May 27 and July 20, 1979. The final transient produced approximately two seconds of coolant boiling, cladding dryout, and incipient fuel pin failure. The facility and test hardware performed as designed, allowing completion of all planned tests and achievement of all test objectives

  17. FIX-II/2032, BWR Pump Trip Experiment 2032, Simulation Mass Flow and Power Transients

    International Nuclear Information System (INIS)

    1988-01-01

    1 - Description of test facility: In the FIX-II pump trip experiments, mass flow and power transients were simulated subsequent to a total loss of power to the recirculation pumps in an internal pump boiling water reactor. The aim was to determine the initial power limit to give dryout in the fuel bundle for the specified transient. In addition, the peak cladding temperature was measured and the rewetting was studied. 2 - Description of test: Pump trip experiment 2032 was a part of test group 2, i.e. the mass flow transient was to simulate the pump coast down with a pump inertia of 11.3 kg.m -2 . The initial power in the 36-rod bundle was 4.44 MW which gave dryout after 1.4 s from the start of the flow transient. A maximum rod cladding temperature of 457 degrees C was measured. Rewetting was obtained after 7.6 s. 3 - Experimental limitations or shortcomings: No ECCS injection systems

  18. Effects of high density dispersion fuel loading on the uncontrolled reactivity insertion transients of a low enriched uranium fueled material test research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Farhan [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)], E-mail: farhan73@hotmail.com; Majid, Asad [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)

    2009-08-15

    The effects of using high density low enriched uranium on the uncontrolled reactivity insertion transients of a material test research reactor were studied. For this purpose, the low density LEU fuel of an MTR was replaced with high density U-Mo (9w/o) LEU fuels currently being developed under the RERTR program having uranium densities of 6.57 gU/cm{sup 3}, 7.74 gU/cm{sup 3} and 8.57 gU/cm{sup 3}. Simulations were carried out to determine the reactor performance under reactivity insertion transients with totally failed control rods. Ramp reactivities of 0.25$/0.5 s and 1.35$/0.5 s were inserted with reactor operating at full power level of 10 MW. Nuclear reactor analysis code PARET was employed to carry out these calculations. It was observed that when reactivity insertion was 0.25$/0.5 s, the new power level attained increased by 5.8% as uranium density increases from 6.57 gU/cm{sup 3} to 8.90 gU/cm{sup 3}. This results in increased maximum temperatures of fuel, clad and coolant outlet, achieved at the new power level, by 4.7 K, 4.4 K and 2.4 K, respectively. When reactivity insertion was 1.35$/0.5 s, the feedback reactivities were unable to control the reactor which resulted in the bulk boiling of the coolant; the one with the highest fuel density was the first to reach the boiling point.

  19. Using Rising Limb Analysis to Estimate Uptake of Reactive Solutes in Advective and Transient Storage Sub-compartments of Stream Ecosystems

    Science.gov (United States)

    Thomas, S. A.; Valett, H.; Webster, J. R.; Mulholland, P. J.; Dahm, C. N.

    2001-12-01

    Identifying the locations and controls governing solute uptake is a recent area of focus in studies of stream biogeochemistry. We introduce a technique, rising limb analysis (RLA), to estimate areal nitrate uptake in the advective and transient storage (TS) zones of streams. RLA is an inverse approach that combines nutrient spiraling and transient storage modeling to calculate total uptake of reactive solutes and the fraction of uptake occurring within the advective sub-compartment of streams. The contribution of the transient storage zones to solute loss is determined by difference. Twelve-hour coinjections of conservative (Cl-) and reactive (15NO3) tracers were conducted seasonally in several headwater streams among which AS/A ranged from 0.01 - 2.0. TS characteristics were determined using an advection-dispersion model modified to include hydrologic exchange with a transient storage compartment. Whole-system uptake was determined by fitting the longitudinal pattern of NO3 to first-order, exponential decay model. Uptake in the advective sub-compartment was determined by collecting a temporal sequence of samples from a single location beginning with the arrival of the solute front and concluding with the onset of plateau conditions (i.e. the rising limb). Across the rising limb, 15NO3:Cl was regressed against the percentage of water that had resided in the transient storage zone (calculated from the TS modeling). The y-intercept thus provides an estimate of the plateau 15NO3:Cl ratio in the absence of NO3 uptake within the transient storage zone. Algebraic expressions were used to calculate the percentage of NO3 uptake occurring in the advective and transient storage sub-compartments. Application of RLA successfully estimated uptake coefficients for NO3 in the subsurface when the physical dimensions of that habitat were substantial (AS/A > 0.2) and when plateau conditions at the sampling location consisted of waters in which at least 25% had resided in the

  20. LIMITS ON THE EVENT RATES OF FAST RADIO TRANSIENTS FROM THE V-FASTR EXPERIMENT

    International Nuclear Information System (INIS)

    Wayth, Randall B.; Tingay, Steven J.; Deller, Adam T.; Brisken, Walter F.; Thompson, David R.; Wagstaff, Kiri L.; Majid, Walid A.

    2012-01-01

    We present the first results from the V-FASTR experiment, a commensal search for fast transient radio bursts using the Very Long Baseline Array (VLBA). V-FASTR is unique in that the widely spaced VLBA antennas provide a discriminant against non-astronomical signals and a mechanism for the localization and identification of events that is not possible with single dishes or short baseline interferometers. Thus, far V-FASTR has accumulated over 1300 hr of observation time with the VLBA, between 90 cm and 3 mm wavelength (327 MHz-86 GHz), providing the first limits on fast transient event rates at high radio frequencies (>1.4 GHz). V-FASTR has blindly detected bright individual pulses from seven known pulsars but has not detected any single-pulse events that would indicate high-redshift impulsive bursts of radio emission. At 1.4 GHz, V-FASTR puts limits on fast transient event rates comparable with the PALFA survey at the Arecibo telescope, but generally at lower sensitivities, and comparable to the 'fly's eye' survey at the Allen Telescope Array, but with less sky coverage. We also illustrate the likely performance of the Phase 1 SKA dish array for an incoherent fast transient search fashioned on V-FASTR.

  1. Construction of climate change scenarios from transient climate change experiments for the IPCC impacts assessment

    International Nuclear Information System (INIS)

    Viner, D.; Hulme, M.; Raper, S.C.B.; Jones, P.D.

    1994-01-01

    This paper outlines the different methods which may be used for the construction of regional climate change scenarios. The main focus of the paper is the construction of global climate change scenarios from climate change experiments carried out using General Circulation Models (GCMS) An introduction to some GCM climate change experiments highlights the difference between model types and experiments (e.g., equilibrium or transient). The latest generation of climate change experiments has been performed using fully coupled ocean-atmosphere GCMS. These allow transient simulations of climate change to be performed with respect to a given greenhouse gas forcing scenario. There are, however, a number of problems with these simulations which pose difficulties for the construction of climate change scenarios for use in climate change impacts assessment. The characteristics of the transient climate change experiments which pose difficulties for the construction of climate change scenarios are discussed. Three examples of these problems are: different climate change experiments use different greenhouse gas concentration scenarios; the 'cold-start' problem makes it difficult to link future projections of climate change to a given calendar year; a drift of the climate is noticeable in the control simulations. In order to construct climate change scenarios for impacts assessment a method has therefore to be employed which addresses these problems. At present the climate modeling and climate change impacts communities are somewhat polarized in their approach to spatial scales. Current GCMs model the climate at resolutions larger than 2.5 x 3.75 degree, while the majority of impacts assessment studies are undertaken at scales below 50km (or 0.5 degree). This paper concludes by addressing the problems in bringing together these two different modeling perspectives by presenting a number of regional climate change scenarios. 35 refs., 8 figs., 2 tabs

  2. Sodium boiling and mixed oxide fuel thermal behavior in FBR undercooling transients; W-1 SLSF experiment results

    International Nuclear Information System (INIS)

    Henderson, J.M.; Wood, S.A.; Knight, D.D.

    1981-01-01

    The W-1 Sodium Loop Safety Facility (SLSF) Experiment was conducted to study fuel pin heat release characteristics during a series of LMFBR Loss-of-Piping Integrity (LOPI) transients and to investigate a regime of coolant boiling during a second series of transients at low, medium and high bundle power levels. The LOPI transients produced no coolant boiling and showed only small changes in coolant temperatures as the test fuel microstructure changed from a fresh, unrestructured to a low burnup, restructured condition. During the last of seven boiling transients, intense coolant boiling produced inlet flow reversal, cladding dryout and moderate cladding melting

  3. VHTRC experiment for verification test of H{infinity} reactivity estimation method

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Yoshio; Suzuki, Katsuo; Akino, Fujiyoshi; Yamane, Tsuyoshi; Fujisaki, Shingo; Takeuchi, Motoyoshi; Ono, Toshihiko [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-02-01

    This experiment was performed at VHTRC to acquire the data for verifying the H{infinity} reactivity estimation method. In this report, the experimental method, the measuring circuits and data processing softwares are described in details. (author).

  4. Test on the reactor with the portable digital reactivity meter for physical experiment

    International Nuclear Information System (INIS)

    Huang Liyuan

    2010-01-01

    Test must be performed on the zero power reactor During the development of portable digital reactivity meter for physical experiment, in order to check its measurement function and accuracy. It describes the test facility, test core, test methods, test items and test results. The test results show that the instrument satisfy the requirements of technical specification, and satisfy the reactivity measurement in the physical experiments on reactors. (authors)

  5. The development of high performance numerical simulation code for transient groundwater flow and reactive solute transport problems based on local discontinuous Galerkin method

    International Nuclear Information System (INIS)

    Suzuki, Shunichi; Motoshima, Takayuki; Naemura, Yumi; Kubo, Shin; Kanie, Shunji

    2009-01-01

    The authors develop a numerical code based on Local Discontinuous Galerkin Method for transient groundwater flow and reactive solute transport problems in order to make it possible to do three dimensional performance assessment on radioactive waste repositories at the earliest stage possible. Local discontinuous Galerkin Method is one of mixed finite element methods which are more accurate ones than standard finite element methods. In this paper, the developed numerical code is applied to several problems which are provided analytical solutions in order to examine its accuracy and flexibility. The results of the simulations show the new code gives highly accurate numeric solutions. (author)

  6. The influence of the reactivity ramp on the course of the power transient in the MARK 1A core of the SNR 300

    International Nuclear Information System (INIS)

    Froehlich, R.; Schmuck, P.

    1976-01-01

    The course of a hypothetic transient overpower accident caused by the onset of a not further specified reactivity ramp accompanied by the simultaneous failure of both shutdown systems must be analyzed in the SNR 300 Mark 1A core licensing procedure. The present study is limited to the discussion of the starting and shutdown phases of such accidents for the fresh core. Depending on the operational state of the reactor, the core geometry is still intact during the starting phase. In the following shutdown phase (core disassembly phase), large-scale mass transfer leads to the nuclear shutdown of the reactor. (orig./AK) [de

  7. HECTR [Hydrogen Event: Containment Transient Response] analyses of the Nevada Test Site (NTS) premixed combustion experiments

    International Nuclear Information System (INIS)

    Wong, C.C.

    1988-11-01

    The HECTR (Hydrogen Event: Containment Transient Response) computer code has been developed at Sandia National Laboratories to predict the transient pressure and temperature responses within reactor containments for hypothetical accidents involving the transport and combustion of hydrogen. Although HECTR was designed primarily to investigate these phenomena in LWRs, it may also be used to analyze hydrogen transport and combustion experiments as well. It is in this manner that HECTR is assessed and empirical correlations, such as the combustion completeness and flame speed correlations for the hydrogen combustion model, if necessary, are upgraded. In this report, we present HECTR analyses of the large-scale premixed hydrogen combustion experiments at the Nevada Test Site (NTS) and comparison with the test results. The existing correlations in HECTR version 1.0, under certain conditions, have difficulty in predicting accurately the combustion completeness and burn time for the NTS experiments. By combining the combustion data obtained from the NTS experiments with other experimental data (FITS, VGES, ACUREX, and Whiteshell), a set of new and better combustion correlations was generated. HECTR prediction of the containment responses, using a single-compartment model and EPRI-provided combustion completeness and burn time, compares reasonably well against the test results. However, HECTR prediction of the containment responses using a multicompartment model does not compare well with the test results. This discrepancy shows the deficiency of the homogeneous burning model used in HECTR. To overcome this deficiency, a flame propagation model is highly recommended. 16 refs., 84 figs., 5 tabs

  8. Simulation of reactivity-initiated accident transients on UO2-M5® fuel rods with ALCYONE V1.4 fuel performance code

    Directory of Open Access Journals (Sweden)

    Isabelle Guénot-Delahaie

    2018-03-01

    Full Text Available The ALCYONE multidimensional fuel performance code codeveloped by the CEA, EDF, and AREVA NP within the PLEIADES software environment models the behavior of fuel rods during irradiation in commercial pressurized water reactors (PWRs, power ramps in experimental reactors, or accidental conditions such as loss of coolant accidents or reactivity-initiated accidents (RIAs. As regards the latter case of transient in particular, ALCYONE is intended to predictively simulate the response of a fuel rod by taking account of mechanisms in a way that models the physics as closely as possible, encompassing all possible stages of the transient as well as various fuel/cladding material types and irradiation conditions of interest. On the way to complying with these objectives, ALCYONE development and validation shall include tests on PWR-UO2 fuel rods with advanced claddings such as M5® under “low pressure–low temperature” or “high pressure–high temperature” water coolant conditions.This article first presents ALCYONE V1.4 RIA-related features and modeling. It especially focuses on recent developments dedicated on the one hand to nonsteady water heat and mass transport and on the other hand to the modeling of grain boundary cracking-induced fission gas release and swelling. This article then compares some simulations of RIA transients performed on UO2-M5® fuel rods in flowing sodium or stagnant water coolant conditions to the relevant experimental results gained from tests performed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities. It shows in particular to what extent ALCYONE—starting from base irradiation conditions it itself computes—is currently able to handle both the first stage of the transient, namely the pellet-cladding mechanical interaction phase, and the second stage of the transient, should a boiling crisis occur.Areas of improvement are finally discussed with a view to simulating and

  9. Update on the Commensal VLA Low-band Ionospheric and Transient Experiment (VLITE)

    Science.gov (United States)

    Kassim, Namir E.; Clarke, Tracy E.; Ray, Paul S.; Polisensky, Emil; Peters, Wendy M.; Giacintucci, Simona; Helmboldt, Joseph F.; Hyman, Scott D.; Brisken, Walter; Hicks, Brian; Deneva, Julia S.

    2017-01-01

    The JVLA Low-band Ionospheric and Transient Experiment (VLITE) is a commensal observing system on the NRAO JVLA. The separate optical path of the prime-focus sub-GHz dipole feeds and the Cassegrain-focus GHz feeds provided an opportunity to expand the simultaneous frequency operation of the JVLA through joint observations across both systems. The low-band receivers on 10 JVLA antennas are outfitted with dedicated samplers and use spare fibers to transport the 320-384 MHz band to the VLITE correlator. The initial phase of VLITE uses a custom-designed real-time DiFX software correlator to produce autocorrelations, as well as parallel and cross-hand cross-correlations from the linear dipole feeds. NRL and NRAO have worked together to explore the scientific potential of the commensal low frequency system for ionospheric remote sensing, astrophysics and transients. VLITE operates at nearly 70% wall time with roughly 6200 hours of JVLA time recorded each year.VLITE data are used in real-time for ionospheric research and are transferred daily to NRL for processing in the astrophysics and transient pipelines. These pipelines provide automated radio frequency interference excision, calibration, imaging and self-calibration of data.We will review early scientific results from VLITE across all three science focus areas, including the ionosphere, slow (> 1 sec) transients, and astrophysics. We also discuss the future of the project, that includes its planned expansion to eVLITE including the addition of more antennas, and a parallel capability to search for fast (complement NRAO’s 3 GHz VLA Sky Survey (VLASS). Revised pipelines are under development for operation during the on-the-fly operation mode of the sky survey.

  10. Transient wave behaviour over an underwater sliding hump from experiments and analytical and numerical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Callaghan, David P.; Nielsen, Peter [The University of Queensland, School of Civil Engineering, Brisbane (Australia); Ahmadi, Afshin [Kellogg Brown and Root Pty Ltd, Brisbane, QLD (Australia)

    2011-12-15

    Flume measurements of a one-dimensional sliding hump starting from rest in quiescence fresh water indicate that when the hump travels at speed less than the shallow-water wave celerity, three waves emerge, travelling in two directions. One wave travels in the opposite direction to the sliding hump at approximately the shallow-water wave celerity (backward free wave). Another wave travels approximately in step with the hump (forced wave), and the remaining wave travels in the direction of the hump at approximately the shallow-water wave celerity (forward free wave). These experiments were completed for a range of sliding hump speed relative to the shallow-water wave celerity, up to unity of this ratio, to investigate possible derivation from solutions of the Euler equation with non-linear and non-hydrostatic terms being included or excluded. For the experimental arrangements tested, the forced waves were negative (depression or reduced water surface elevation) waves while the free waves were positive (bulges or increased water surface elevation). For experiments where the sliding hump travelled at less than 80% of the shallow-water wave celerity did not include transient behaviour measurements (i.e. when the three waves still overlapped). The three wave framework was partially supported by these measurements in that the separated forward and forced waves were compared to measurements. For the laboratory scale experiments, the forward free wave height was predicted reasonably by the long-wave equation (ignoring non-linear and non-hydrostatic terms) when the sliding hump speed was less than 80% of the shallow-water wave celerity. The forced wave depression magnitude required the Euler equations for all hump speed tested. The long-wave solution, while being valid in a limited parameter range, does predict the existence of the three waves as found in these experiments (forward travelling waves measured quantitatively while the backward travelling waves visually by video

  11. Preemptive, but not reactive, spinal cord stimulation mitigates transient ischemia-induced myocardial infarction via cardiac adrenergic neurons

    NARCIS (Netherlands)

    Southerland, E. M.; Milhorn, D. M.; Foreman, R. D.; Linderoth, B.; DeJongste, M. J. L.; Armour, J. A.; Subramanian, V.; Singh, M.; Singh, K.; Ardell, J. L.

    2007-01-01

    Our objective was to determine whether electrical neuromodulation using spinal cord stimulation ( SCS) mitigates transient ischemia-induced ventricular infarction and, if so, whether adrenergic neurons are involved in such cardioprotection. The hearts of anesthetized rabbits, subjected to 30 min of

  12. The biofiltration permeable reactive barrier: Practical experience from Synthesia

    Energy Technology Data Exchange (ETDEWEB)

    Vesela, L.; Nemecek, J.; Siglova, M.; Kubal, M. [DEKONTA, Prague (Czech Republic)

    2006-10-15

    The paper refers to utilization of biological elements within permeable reactive barriers. The concept of a biofiltration permeable barrier has been tested in the laboratory and in pilot-scale. Oxyhumolite (oxidized young lignite) was examined as an absorption material and a biofilm carrier. Laboratory tests performed before the pilot verification confirmed that oxyhumolite adsorbs organic pollutants at a minimum value, but that it can be used for biofilm attachment. An experimental barrier was built on premises of a chemical factory contaminated mainly by various organic pollutants (benzene, toluene, ethylbenzene, and xylenes (BTEX), chlorobenzenes, naphthalene, nitro-derivatives, phenols, trichloroethylene (TCE), and total petroleum hydrocarbon (TPH)). Before the barrier was installed, a preliminary survey of the unsaturated zone, hydrogeological investigation, and a microbiological survey had been performed. The barrier was designed as a trench-and-gate system with an in situ bioreactor. During the year 2004, measurements of groundwater flux and retention time under current hydrological conditions, together with chemical and microbiological monitoring, were carried out on the site. The results showed high effectiveness of organic contamination removal. Average elimination varied from 57.3% (naphthalene) to 99.9% (nitro-derivatives, BTEX); microbial density in the bioreactor was approx. 10{sup 5} CFU mL{sup -1}.

  13. Transient Fuel Behavior and Failure Condition in the CABRI-2 Experiments

    International Nuclear Information System (INIS)

    Sato, Ikken; Lemoine, Francette; Struwe, Dankward

    2004-01-01

    In the CABRI-2 program, 12 tests were performed under various transient conditions covering a wide range of accident scenarios using two types of preirradiated fast breeder reactor (FBR) fuel pins with different smear densities and burnups. For each fuel, a nonfailure-transient test was performed, and it provided basic information such as fuel thermal condition, fuel swelling, and gas release. From the failure tests, information on failure mode, failure time, and axial location was obtained. Based on this information, failure conditions such as fuel enthalpy and cladding temperature were evaluated. These failure conditions were compared with the CABRI-1 tests in which different fuels as well as different transient conditions were used. This comparison, together with supporting information available from existing in-pile and out-of-pile experiments, allowed an effective understanding on failure mechanisms depending on fuel and transient conditions. It is concluded that pellet-cladding mechanical interaction (PCMI) due to fuel thermal expansion and fission-gas-induced swelling is playing an important role on mechanical clad loading especially with high smear density and low fuel-heating-rate conditions. At very high heating-rate conditions, there is no sufficient time to allow significant fuel swelling, so that cavity pressurization with fuel melting becomes the likely failure mechanism. Fuel smear density and fission-gas retention have a strong impact both on PCMI and cavity pressurization. Furthermore, pin failure is strongly dependent on cladding temperature, which plays an important role in the axial failure location. With the low smear-density fuel, considerable PCMI mitigation is possible leading to a high failure threshold as well as in-pin molten-fuel relocation along the central hole. However, even with the low smear density fuel, PCMI failure could take place with an elevated cladding-temperature condition. On the other hand, in case of a sufficiently long

  14. Detailed characterization of a Comparative Reactivity Method (CRM) instrument for ambient OH reactivity measurements: experiments vs. modeling

    Science.gov (United States)

    Michoud, Vincent; Locoge, Nadine; Dusanter, Sébastien

    2015-04-01

    The Hydroxyl radical (OH) is the main daytime oxidant in the troposphere, leading to the oxidation of Volatile Organic Compounds (VOCs) and the formation of harmful pollutants such as ozone (O3) and Secondary Organic Aerosols (SOA). While OH plays a key role in tropospheric chemistry, recent studies have highlighted that there are still uncertainties associated with the OH budget, i.e the identification of sources and sinks and the quantification of production and loss rates of this radical. It has been demonstrated that ambient measurements of the total OH loss rate (also called total OH reactivity) can be used to identify and reduce these uncertainties. In this context, the Comparative Reactivity Method (CRM), developed by Sinha et al. (ACP, 2008), is a promising technique to measure total OH reactivity in ambient air and has already been used during several field campaigns. This technique relies on monitoring competitive reactions of OH with ambient trace gases and a reference compound (pyrrole) in a sampling reactor to derive ambient OH reactivity. However, this technique requires a complex data processing chain that has yet to be carefully investigated in the laboratory. In this study, we present a detailed characterization of a CRM instrument developed at Mines Douai, France. Experiments have been performed to investigate the dependence of the CRM response on humidity, ambient NOx levels, and the pyrrole-to-OH ratio inside the sampling reactor. Box modelling of the chemistry occurring in the reactor has also been performed to assess our theoretical understanding of the CRM measurement. This work shows that the CRM response is sensitive to both humidity and NOx, which can be accounted for during data processing using parameterizations depending on the pyrrole-to-OH ratio. The agreement observed between laboratory studies and model results suggests a good understanding of the chemistry occurring in the sampling reactor and gives confidence in the CRM

  15. Disruption of the blood-brain interface in neonatal rat neocortex induces a transient expression of metallothionein in reactive astrocytes

    DEFF Research Database (Denmark)

    Penkowa, M; Moos, T

    1995-01-01

    rats were subjected to a localized freeze lesion of the neocortex of the right temporal cortex. This lesion results in a disrupted blood-brain interface, leading to extravasation of plasma proteins. From 16 h, reactive astrocytosis, defined as an increase in the number and size of cells expressing GFAP...

  16. Twenty-five years of transient counting experience in French PWR units

    Energy Technology Data Exchange (ETDEWEB)

    Barthelet, B. [Electricite de France (EDF DPN), 93 - Saint-Denis (France); Savoldelli, D.; Fritz, R. [Electricite de France (EDF DPN), 93 - Noisy le Grand (France)

    2001-07-01

    For nearly twenty five years, EDF has been checking that the actual operating transients are neither more severe nor more numerous than the design basis transients. This activity of transient cycle counting and bookkeeping has enabled EDF to own a database of more than 800 reactor.years for the PWR units. The current method of transient cycle counting is presented. In the paper, we will point out the main results of transient cycle counting and lessons learned. In general, the frequencies of transients are lower than the design frequencies. In few cases, they are higher, such as the transient frequencies of the RCS lines connected to auxiliary systems often due to operating procedures or particular periodic testing. Few periodic tests were not taken into account in the design basis transient file ; they have been detected thanks to the transient cycle counting. In the last 1980's, we achieved the first updating of the design basis transient file for the PWR 900 MWe series. In the early 1990's, we updated the design basis transient file of the PWR 1300 MWe series. In fact, since design and start-up, the operating conditions have been modified (fuel cycle with stretch-out, modification of the hot leg and cold leg temperatures for the PWR 1300 MWe,...). This was the cause of many unclassified transients. In the new design basis transient file, we have created new transients and increased the frequencies of some of them. This has enabled to consider the updated design basis transient file more representative of actual operating transients. For some years, we have increasingly associated the operators with the transient cycle counting concern. We noticed progress (decreased frequencies of most transients). (authors)

  17. Twenty-five years of transient counting experience in French PWR units

    International Nuclear Information System (INIS)

    Barthelet, B.; Savoldelli, D.; Fritz, R.

    2001-01-01

    For nearly twenty five years, EDF has been checking that the actual operating transients are neither more severe nor more numerous than the design basis transients. This activity of transient cycle counting and bookkeeping has enabled EDF to own a database of more than 800 reactor.years for the PWR units. The current method of transient cycle counting is presented. In the paper, we will point out the main results of transient cycle counting and lessons learned. In general, the frequencies of transients are lower than the design frequencies. In few cases, they are higher, such as the transient frequencies of the RCS lines connected to auxiliary systems often due to operating procedures or particular periodic testing. Few periodic tests were not taken into account in the design basis transient file ; they have been detected thanks to the transient cycle counting. In the last 1980's, we achieved the first updating of the design basis transient file for the PWR 900 MWe series. In the early 1990's, we updated the design basis transient file of the PWR 1300 MWe series. In fact, since design and start-up, the operating conditions have been modified (fuel cycle with stretch-out, modification of the hot leg and cold leg temperatures for the PWR 1300 MWe,...). This was the cause of many unclassified transients. In the new design basis transient file, we have created new transients and increased the frequencies of some of them. This has enabled to consider the updated design basis transient file more representative of actual operating transients. For some years, we have increasingly associated the operators with the transient cycle counting concern. We noticed progress (decreased frequencies of most transients). (authors)

  18. Fringe-controlled biodegradation under dynamic conditions: Quasi 2-D flow-through experiments and reactive-transport modeling

    Science.gov (United States)

    Eckert, Dominik; Kürzinger, Petra; Bauer, Robert; Griebler, Christian; Cirpka, Olaf A.

    2015-01-01

    Biodegradation in contaminated aquifers has been shown to be most pronounced at the fringe of contaminant plumes, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. While physical mixing of contaminant and electron acceptor by transverse dispersion has been shown to be the major bottleneck for biodegradation in steady-state plumes, so far little is known on the effect of flow and transport dynamics (caused, e.g., by a seasonally fluctuating groundwater table) on biodegradation in these systems. Towards this end we performed experiments in quasi-two-dimensional flow-through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth, also maintenance and dormancy are important processes that affect biodegradation performance under transient environmental conditions and therefore deserve increased consideration in future reactive-transport modeling.

  19. Fringe-controlled biodegradation under dynamic conditions: quasi 2-D flow-through experiments and reactive-transport modeling.

    Science.gov (United States)

    Eckert, Dominik; Kürzinger, Petra; Bauer, Robert; Griebler, Christian; Cirpka, Olaf A

    2015-01-01

    Biodegradation in contaminated aquifers has been shown to be most pronounced at the fringe of contaminant plumes, where mixing of contaminated water and ambient groundwater, containing dissolved electron acceptors, stimulates microbial activity. While physical mixing of contaminant and electron acceptor by transverse dispersion has been shown to be the major bottleneck for biodegradation in steady-state plumes, so far little is known on the effect of flow and transport dynamics (caused, e.g., by a seasonally fluctuating groundwater table) on biodegradation in these systems. Towards this end we performed experiments in quasi-two-dimensional flow-through microcosms on aerobic toluene degradation by Pseudomonas putida F1. Plume dynamics were simulated by vertical alteration of the toluene plume position and experimental results were analyzed by reactive-transport modeling. We found that, even after disappearance of the toluene plume for two weeks, the majority of microorganisms stayed attached to the sediment and regained their full biodegradation potential within two days after reappearance of the toluene plume. Our results underline that besides microbial growth, also maintenance and dormancy are important processes that affect biodegradation performance under transient environmental conditions and therefore deserve increased consideration in future reactive-transport modeling. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Coherent optical transients observed in rubidium atomic line filtered Doppler velocimetry experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fajardo, Mario E., E-mail: mario.fajardo@eglin.af.mil; Molek, Christopher D.; Vesely, Annamaria L. [Air Force Research Laboratory, Munitions Directorate, Ordnance Division, Energetic Materials Branch, AFRL/RWME, 2306 Perimeter Road, Eglin AFB, Florida 32542-5910 (United States)

    2015-10-14

    We report the first successful results from our novel Rubidium Atomic Line Filtered (RALF) Doppler velocimetry apparatus, along with unanticipated oscillatory signals due to coherent optical transients generated within pure Rb vapor cells. RALF is a high-velocity and high-acceleration extension of the well-known Doppler Global Velocimetry (DGV) technique for constructing multi-dimensional flow velocity vector maps in aerodynamics experiments [H. Komine, U.S. Patent No. 4,919,536 (24 April 1990)]. RALF exploits the frequency dependence of pressure-broadened Rb atom optical absorptions in a heated Rb/N{sub 2} gas cell to encode the Doppler shift of reflected near-resonant (λ{sub 0} ≈ 780.24 nm) laser light onto the intensity transmitted by the cell. The present RALF apparatus combines fiber optic and free-space components and was built to determine suitable operating conditions and performance parameters for the Rb/N{sub 2} gas cells. It yields single-spot velocities of thin laser-driven-flyer test surfaces and incorporates a simultaneous Photonic Doppler Velocimetry (PDV) channel [Strand et al., Rev. Sci. Instrum. 77, 083108 (2006)] for validation of the RALF results, which we demonstrate here over the v = 0 to 1 km/s range. Both RALF and DGV presume the vapor cells to be simple Beer's Law optical absorbers, so we were quite surprised to observe oscillatory signals in experiments employing low pressure pure Rb vapor cells. We interpret these oscillations as interference between the Doppler shifted reflected light and the Free Induction Decay (FID) coherent optical transient produced within the pure Rb cells at the original laser frequency; this is confirmed by direct comparison of the PDV and FID signals. We attribute the different behaviors of the Rb/N{sub 2} vs. Rb gas cells to efficient dephasing of the atomic/optical coherences by Rb-N{sub 2} collisions. The minimum necessary N{sub 2} buffer gas density ≈0.3 amagat translates into a

  1. Experiment data report for Loft anticipated transient experiments 16-1, 16-2, and 16-3

    International Nuclear Information System (INIS)

    Batt, D.L.; Carpenter, J.M.

    1980-12-01

    This report presents uninterpreted experimental data from the second, third, and fourth anticipated transient experiments (Experiments L6-2, L6-1, and L6-3), conducted in the Loss-of-Fluid Test (LOFT) facility. Experiment L6-2 simulated a loss of forced primary coolant flow in a large PWR by tripping power to primary coolant pump motor generator sets, allowing the pumps to coast down under the influence of the flywheel system. Reactor scram initiated on indication of low flow in the primary coolant system (PCS). Experiment L6-1 simulated a loss of steam load in a large PWR by closing the steam flow control valve which reduced heat removal from the secondary coolant system and caused the PCS temperature and pressure to increase until reactor scram initiated on indication on high PCS pressure. Experiment L6-3 simulated an excessive load increase in a large PWR by opening the steam flow control valve at its maximum rate. PCS temperature and pressure decreased, causing the reactor to scram on indication of low PCS pressure. All experiments were complete when the plant was returned to a hot-standby condition

  2. Experiments on transient melting of tungsten by ELMs in ASDEX Upgrade

    Science.gov (United States)

    Krieger, K.; Balden, M.; Coenen, J. W.; Laggner, F.; Matthews, G. F.; Nille, D.; Rohde, V.; Sieglin, B.; Giannone, L.; Göths, B.; Herrmann, A.; de Marne, P.; Pitts, R. A.; Potzel, S.; Vondracek, P.; ASDEX-Upgrade Team; EUROfusion MST1 Team

    2018-02-01

    Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the divertor manipulator II (DIM-II) system (Herrmann et al 2015 Fusion Eng. Des. 98-9 1496-9). Designed as near replicas of the geometries used also in separate experiments on the JET tokamak (Coenen et al 2015 J. Nucl. Mater. 463 78-84 Coenen et al 2015 Nucl. Fusion 55 023010; Matthews et al 2016 Phys. Scr. T167 7), the samples featured a misaligned leading edge and a sloped ridge respectively. Both structures protrude above the default target plate surface thus receiving an increased fraction of the parallel power flux. Transient melting by ELMs was induced by moving the outer strike point to the sample location. The temporal evolution of the measured current flow from the samples to vessel potential confirmed transient melting. Current magnitude and dependency from surface temperature provided strong evidence for thermionic electron emission as main origin of the replacement current driving the melt motion. The different melt patterns observed after exposures at the two sample geometries support the thermionic electron emission model used in the MEMOS melt motion code, which assumes a strong decrease of the thermionic net current at shallow magnetic field to surface angles (Pitts et al 2017 Nucl. Mater. Energy 12 60-74). Post exposure ex situ analysis of the retrieved samples show recrystallization of tungsten at the exposed surface areas to a depth of up to several mm. The melt layer transport to less exposed surface areas leads to ratcheting pile up of re-solidified debris with zonal growth extending from the already enlarged grains at the surface.

  3. 3-D transient eddy current calculations for the FELIX cylinder experiments

    International Nuclear Information System (INIS)

    Davey, K.R.; Turner, L.R.

    1986-12-01

    The three-dimensional eddy current transient field problem is formulated first using the U-V method. This method breaks the vector Helmholtz equation into two scalar Helmholtz equations. Null field integral equations and the appropriate boundary conditions are used to set up an identification matrix which is independent of null field point locations. Embedded in the identification matrix are the unknown eigenvalues of the problem representing its impulse response in time. These eigenvalues are found by equating the determinant of the identification matrix to zero. When this initial forcing function is Fourier decomposed into its spatial harmonics, each Fourier component can be associated with a unique eigenvalue by this technique. The true transient solution comes through a convolution of the impulse response so obtained with the particular external field decay governing the problem at hand. The technique is applied to the FELIX cylinder experiments; computed results are compared to data. A pseudoanalytic confirmation of the eigenvalues so obtained is formulated to validate the procedure

  4. The analysis with the code TANK of a postulated reactivity-insertion transient in a 10-MW MAPLE research reactor

    International Nuclear Information System (INIS)

    Ellis, R.J.

    1990-10-01

    This report discusses the analysis of a postulated loss-of-regulation (LOR) accident in a metal-fuelled MAPLE Research Reactor. The selected transient scenario involves a slow LOR from low reactor power; the control rods are assumed to withdraw slowly until a trip at 12 MW halts the withdrawal. The simulation was performed using the space-time reactor kinetics computer code TANK, and modelling the reactor in detail in two dimensions and in two neutron-energy groups. Emphasis in this report is placed on the modelling techniques used in TANK and the physics considerations of the analysis

  5. Calculations of transient fields in the Felix experiments at Argonne using null field integrated techniques

    International Nuclear Information System (INIS)

    Han, H.C.; Davey, K.R.; Turner, L.

    1985-08-01

    The transient eddy current problem is characteristically computationally intensive. The motivation for this research was to realize an efficient, accurate, solution technique involving small matrices via an eigenvalue approach. Such a technique is indeed realized and tested using the null field integral technique. Using smart (i.e., efficient, global) basis functions to represent unknowns in terms of a minimum number of unknowns, homogeneous eigenvectors and eigenvalues are first determined. The general excitatory response is then represented in terms of these eigenvalues/eigenvectors. Excellent results are obtained for the Argonne Felix cylinder experiments using a 4 x 4 matrix. Extension to the 3-D problem (short cylinder) is set up in terms of an 8 x 8 matrix

  6. Parametric study of postulated reactivity transients due to ingress of heavy water from the reflector tank into the converted core of APSARA reactor

    International Nuclear Information System (INIS)

    Sankaranarayanan, S.

    2004-01-01

    Research reactors in the power range 5-10 MW with useable neutron flux values >1.OE+14 n/sqcm/sec can be constructed using LEU fuel with light water for neutron moderation and fuel cooling. In order to obtain a large irradiation volume, a heavy water reflector is used where fairly high neutron flux levels can be obtained. A prototype LEU fuelled 5/10 MW reactor design has been developed in the Bhabha Atomic Research Centre in Trombay. Work is on hand to carry out technology simulation of this reactor design by converting the pool type reactor APSARA in BARC. Presently the Apsara reactor uses MTh type high enriched U-Al alloy plate type fuel loaded in a 7x7 grid with a square lattice pitch of 76.8 mm. The reactor has three control-scram-shut off rods and one regulating control rod. In the first phase of the simulation studies, it is proposed to use the existing high enriched uranium fuel in a modified core with 37 positions arranged with a square lattice pitch of 84.8 mm, surrounded by a 50 cm thick heavy water reflector. Subsequently the converted core will use plate-type low enriched uranium suicide fuel. One of the accident scenarios postulated for the safety evaluation of the modified APSARA reactor is the reactivity transient due to the ingress of heavy water into the core through a small sized rupture in the aluminium wall of the reflector tank. Parametric analyses were done for the safety evaluation of modified Apsara reactor, for postulated leak of heavy water into the core from the reflector tank. A simplified computer code REDYN, based on point model reactor kinetics with one effective group of delayed neutrons is used for the analyses. Results of several parametric cases used in the study show that it is possible to contain the consequences of this type of reactivity transient within acceptable fuel and coolant thermal safety limits

  7. Results from transient transport experiments in Rijnhuizen tokamak project: Heat convection, transport barriers and 'non-local' effects

    International Nuclear Information System (INIS)

    Mantica, P.; Gorini, G.; Hogeweij, G.M.D.; Kloe, J. de; Lopez Cardozo, N.J.; Schilham, A.M.R.

    2001-01-01

    An overview of experimental transport studies performed on the Rijnhuizen Tokamak Project (RTP) using transient transport techniques in both Ohmic and ECH dominated plasmas is presented. Modulated Electron Cyclotron Heating (ECH) and oblique pellet injection (OPI) have been used to induce electron temperature (T e ) perturbations at different radial locations. These were used to probe the electron transport barriers observed near low order rational magnetic surfaces in ECH dominated steady-state RTP plasmas. Layers of inward electron heat convection in off-axis ECH plasmas were detected with modulated ECH. This suggests that RTP electron transport barriers consist of heat pinch layers rather than layers of low thermal diffusivity. In a different set of experiments, OPI triggered a transient rise of the core T e due to an increase of the T e gradient in the 1< q<2 region. These transient transport barriers were probed with modulated ECH and found to be due to a transient drop of the electron heat diffusivity, except for off-axis ECH plasmas, where a transient inward pinch is also observed. Transient transport studies in RTP could not solve this puzzling interplay between heat diffusion and convection in determining an electron transport barrier. They nevertheless provided challenging experimental evidence both for theoretical modelling and for future experiments. (author)

  8. Keeping the secret: Insights from repeated catchment-scale tracer experiments under transient conditions

    Science.gov (United States)

    Bogner, Christina; Hauhs, Michael; Lange, Holger

    2016-04-01

    Catchment-level tracer experiments are generally performed to identify site-specific hydrological response functions of the catchment. The existence and uniqueness of these response functions are hardly ever questioned. Here, we report on a series of replicated tracer experiments in two small first-order catchments, G1 (0.6 ha, roofed) and F4 (2.3 ha, without roof) at Gårdsjön in SW Sweden. The soils in both catchments are shallow (500 m2) the experiments were done without a roof mostly at transient conditions. The catchment F4 was equipped with a sprinkler system with a watering capacity of around 38-45 m3 day-1. Natural rainfall comes in addition. A bromide tracer solution was injected to groundwater at a single location about 40 m upstream the weir over a period of less than an hour, and was monitored using a set of groundwater tubes and the weir at the outlet over the following 4 days. In addition, discharge was measured. The experiments were repeated each summer from 2007 to 2015. While steady state conditions were guaranteed in G1, steady runoff has been achieved only four times in F4. We investigated tracer recovery rates against cumulated runoff since tracer application. Substantially different transit times and qualitatively different behaviour of the breakthrough curves were observed, even under steady state conditions. In G1, no single system response function could be identified in 5 replicates. Similarly, the catchment response functions in F4 under steady state differed between experiments. However, they remained in a similar range as in G1. Based on these results, we question the identifiability of flow paths and system properties, such as saturated water content or hydrologic transmissivity, at the catchment scale using tracer experiments. Rather, the series demonstrate the utter importance of the initial and boundary conditions which largely determine the response of the system to inert tracer pulses.

  9. Reactive Halogens in the Marine Boundary Layer (RHaMBLe): the tropical North Atlantic experiments

    OpenAIRE

    J. D. Lee; G. McFiggans; J. D. Allan; A. R. Baker; S. M. Ball; A. K. Benton; L. J. Carpenter; R. Commane; B. D. Finley; M. Evans; E. Fuentes; K. Furneaux; A. Goddard; N. Good; J. F. Hamilton

    2010-01-01

    The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth...

  10. Cerebral blood flow and CO2 reactivity in transient ischemic attacks: comparison between TIAs due to the ICA occlusion and ICA mild stenosis

    International Nuclear Information System (INIS)

    Tsuda, Y.; Kimura, K.; Yoneda, S.; Etani, H.; Asai, T.; Nakamura, M.; Abe, H.

    1983-01-01

    Hemispheric mean cerebral blood flow (CBF), together with its CO2 reactivity in response to hyperventilation, was investigated in 18 patients with transient ischemic attacks (TIAs) by intraarterial 133Xe injection method in a subacute-chronic stage of the clinical course. In 8 patients, the lesion responsible for symptoms was regarded as unilateral internal carotid artery (ICA) occlusion, and in 10 patients, it was regarded as unilateral ICA mild stenosis (less than 50% stenosis in diameter). Resting flow values were significantly decreased in the affected hemisphere of TIA due to the ICA occlusion as compared with the unaffected hemisphere of the same patient, regarded as the relative control. It was not decreased in the affected hemisphere of TIA due to the ICA mild stenosis as compared with the control. With respect to the responsiveness of CBF to changes in PaCO2, it was preserved in both TIAs, due to the ICA occlusion and ICA mild stenosis. Vasoparalysis was not observed in either types of TIAs in the subacute-chronic stage. However, in the relationship of blood pressure and CO2 reactivity, expressed as delta CBF(%)/delta PaCO2, pressure-dependent CO2 reactivity as a group was observed with significance in 8 cases of TIA due to the ICA occlusion, while no such relationship was noted in 10 cases of TIA due to the ICA mild stenosis. Moreover, clinical features were different between TIAs due to the ICA occlusion and ICA mild stenosis, i.e., more typical, repeatable TIA (6.3 +/- 3.7 times) with shorter duration (less than 30 minutes) was observed in TIAs due to the ICA mild stenosis, while more prolonged, less repeatable TIA (2.4 +/- 1.4 times) was observed in TIAs due to fixed obstruction of the ICA. From these observations, two different possible mechanisms as to the pathogenesis of TIA might be expected

  11. Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; Arcos, Teresa de los; Benedikt, Jan; Keudell, Achim von [RD Plasmas with Complex Interactions, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum (Germany)

    2013-10-15

    A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP)

  12. Critical experiment tests of bowing and expansion reactivity calculations for LMRS

    International Nuclear Information System (INIS)

    Schaefer, R.W.

    1988-01-01

    Experiments done in several LMR-type critical assemblies simulated core axial expansion, core radial expansion and bowing, coolant expansion, and control driveline expansion. For the most part new experimental techniques were developed to do these experiments. Calculations of the experiments basically used design-level methods, except when it was necessary to investigate complexities peculiar to the experiments. It was found that these feedback reactivities generally are overpredicted, but the predictions are within 30% of the experimental values. 14 refs., 2 figs., 4 tabs

  13. LOFT facility PSS experiments: analysis of wet well vertical loads resulting from transient initiation

    International Nuclear Information System (INIS)

    Berta, V.T.

    1977-05-01

    Fourteen experiments on the Loss-of-Fluid Test (LOFT) facility pressure suppression system (PSS) are analyzed in relation to the vertical load generated on the suppression tank in the first 0.5 sec of the transient. Variations in principle parameters affecting the generation of vertical loads were included in the experiments. The internal and external vent submergences are identified from the analysis as being parameters which are first order in influencing the magnitude of the vertical load. These parameters are geometric in nature and depend only on PSS design. Physical parameters of total energy input and rate of energy input to the dry well, which influence the dry well pressurization, also are identified as being first order in influencing the magnitude of the vertical loads. The vertical load magnitude is a direct function of these geometric and physical parameters. The analysis indicates that a small value in any one of the parameters will cause the vertical load to be small and to have little dependence on the magnitude of the other parameters. In addition, the phenomena of nonuniform nonsynchronized vent inlet pressures, which have origins that are either geometric, physical, or a combination of both, act as a significant vertical load reduction mechanism

  14. Analysis of void reactivity measurements in full MOX BWR physics experiments

    International Nuclear Information System (INIS)

    Ando, Yoshihira; Yamamoto, Toru; Umano, Takuya

    2008-01-01

    In the full MOX BWR physics experiments, FUBILA, four 9x9 test assemblies simulating BWR full MOX assemblies were located in the center of the core. Changing the in-channel moderator condition of the four assemblies from 0% void to 40% and 70% void mock-up, void reactivity was measured using Amplified Source Method (ASM) technique in the subcritical cores, in which three fission chambers were located. ASM correction factors necessary to express the consistency of the detector efficiency between measured core configurations were calculated using collision probability cell calculation and 3D-transport core calculation with the nuclear data library, JENDL-3.3. Measured reactivity worth with ASM correction factor was compared with the calculated results obtained through a diffusion, transport and continuous energy Monte Carlo calculation respectively. It was confirmed that the measured void reactivity worth was reproduced well by calculations. (author)

  15. The Everyday Emotional Experience of Adults with Major Depressive Disorder: Examining Emotional Instability, Inertia, and Reactivity

    Science.gov (United States)

    Thompson, Renee J.; Mata, Jutta; Jaeggi, Susanne M.; Buschkuehl, Martin; Jonides, John; Gotlib, Ian H.

    2013-01-01

    Investigators have begun to examine the temporal dynamics of affect in individuals diagnosed with Major Depressive Disorder (MDD), focusing on instability, inertia, and reactivity of emotion. How these dynamics differ between individuals with MDD and healthy controls have not before been examined in a single study. In the present study, 53 adults with MDD and 53 healthy adults carried hand-held electronic devices for approximately seven days and were prompted randomly eight times per day to report their levels of current negative affect (NA), positive affect (PA), and the occurrence of significant events. In terms of NA, compared with healthy controls, depressed participants reported greater instability and greater reactivity to positive events, but comparable levels of inertia and reactivity to negative events. Neither average levels of NA nor NA reactivity to, frequency or intensity of, events accounted for the group difference in instability of NA. In terms of PA, the MDD and control groups did not differ significantly in their instability, inertia, or reactivity to positive or negative events. These findings highlight the importance of emotional instability in MDD, particularly with respect to NA, and contribute to a more nuanced understanding of the everyday emotional experiences of depressed individuals. PMID:22708886

  16. PWR boron dilution transients. Thermal-hydraulic analyses of PKL-E experiments

    International Nuclear Information System (INIS)

    Pietro Alessandro Di Maio; Antonino Tomasello; Giuseppe Vella

    2005-01-01

    Full text of publication follows: In the field of PWR reactor safety, one of the topics that is currently of major interest worldwide is that of inadvertent boron dilution events. The safety issue involved in such scenarios is that inadvertent transport into the reactor core of un-borated water - or water having only a low boron concentration - can lead to local recriticality and possibly to power excursions. Studies on various accidental sequences that could initiate boron dilution events revealed that some SBLOCAs, occurring in the primary system, lead to reflux condenser conditions and subsequent re-establishment of natural circulation are of particular significance. In this work, the first field of analysis is related to the investigation of the thermal - hydraulic conditions that could lead to boron dilution events, such as the stop of natural circulation within primary system and the subsequent start of reflux condenser functioning mode. The investigation of the primary thermal - hydraulic conditions has been performed using the experimental results obtained in the PKL test integral facility in which some SBLOCA sequences have been carried out. Particular useful were the PKL III E experiments data whose results have been numerically reproduced using the code Relap5/MOD3.3/Beta code, contributing to understand the complex thermalhydraulic phenomena related to a PWR boron dilution event. The second field of analysis is related to the effects that possible displacements of un-borated water slugs towards the Reactor Pressure Vessel (RPV) could have on the core reactivity. A numerical approach using the Relap5 reactor kinetics model has been adopted to integrate the experimental thermal - hydraulic data obtained in the PKL III E tests. A careful analysis has been performed in order to establish which core conditions at incident start could produce the largest reactivity increase as a consequence of restarting of natural circulation during the primary system

  17. PWR boron dilution transients. Thermal-hydraulic analyses of PKL-E experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pietro Alessandro Di Maio; Antonino Tomasello; Giuseppe Vella [Dipartimento di Ingegneria Nucleare, Viale delle Scienze, 90128 Palermo (Italy)

    2005-07-01

    Full text of publication follows: In the field of PWR reactor safety, one of the topics that is currently of major interest worldwide is that of inadvertent boron dilution events. The safety issue involved in such scenarios is that inadvertent transport into the reactor core of un-borated water - or water having only a low boron concentration - can lead to local recriticality and possibly to power excursions. Studies on various accidental sequences that could initiate boron dilution events revealed that some SBLOCAs, occurring in the primary system, lead to reflux condenser conditions and subsequent re-establishment of natural circulation are of particular significance. In this work, the first field of analysis is related to the investigation of the thermal - hydraulic conditions that could lead to boron dilution events, such as the stop of natural circulation within primary system and the subsequent start of reflux condenser functioning mode. The investigation of the primary thermal - hydraulic conditions has been performed using the experimental results obtained in the PKL test integral facility in which some SBLOCA sequences have been carried out. Particular useful were the PKL III E experiments data whose results have been numerically reproduced using the code Relap5/MOD3.3/Beta code, contributing to understand the complex thermalhydraulic phenomena related to a PWR boron dilution event. The second field of analysis is related to the effects that possible displacements of un-borated water slugs towards the Reactor Pressure Vessel (RPV) could have on the core reactivity. A numerical approach using the Relap5 reactor kinetics model has been adopted to integrate the experimental thermal - hydraulic data obtained in the PKL III E tests. A careful analysis has been performed in order to establish which core conditions at incident start could produce the largest reactivity increase as a consequence of restarting of natural circulation during the primary system

  18. Operational experience with reactive power control methods optimized for tokamak power supplies

    International Nuclear Information System (INIS)

    Sihler, C.; Huart, M.; Kaesemann, C.-P.; Streibl, B.

    2003-01-01

    The power and energy of the ASDEX Upgrade (AUG) tokamak are provided by two separate 10.5 kV, 110-85 Hz networks based on the flywheel generators EZ3-EZ4 in addition to the generator EZ2 dedicated to the toroidal field coil. The 10.5 kV networks supply the thyristor converters allowing fast control of the DC currents in the AUG poloidal field coils. Two methods for improving the load power factor in the present experimental campaign of AUG have been investigated, namely the control of the phase-to-neutral voltage in thyristor converters fitted with neutral thyristors, such as the new 145 MVA modular thyristor converter system (Group 6), and reactive power control achieved by means of static VAr compensators (SVC). The paper shows that reliable compensation up to 90 MVAr was regularly achieved and that electrical transients in SVC modules can be kept at an acceptable level. The paper will discuss the results from the reactive power reduction by SVC and neutral thyristor control and draw a comparative conclusion

  19. Transient and intermittent magnetic reconnections in TS-3/UTST merging startup experiments

    International Nuclear Information System (INIS)

    Ono, Y.; Imazawa, R.; Imanaka, H.; Hayamizu, T.; Inomoto, M.; Sato, M.; Kawamori, E.; Ejiri, A.; Takase, Y.; Asai, T.; Takahashi, T.

    2007-01-01

    The high-power reconnection heating has been developed in the TS-3 merging experiments, leading us to a new pulsed high-beta spherical tokamak (ST) formation. Two ST plasmas were produced inductively by two or four PF coils without using any central solenoid (CS) coil and were merged together for MW-GW reconnection heating. The magnetic reconnection transformed the magnetic energy of reconnecting magnetic field through the outflow kinetic energy finally to the ion thermal energy, increasing the plasma beta of ST up to 0.5. A new finding is that ejection of current sheet (or plasmoid) causes high-speed merging/ reconnection as well as high-power heating. In the high-q ST merging, the sheet resistivity was almost classical due to the sheet thickness much longer than ion gyroradius. Large inflow flux and low current-sheet dissipation resulted in flux pileup followed by rapid growth of the current sheet. When the flux pileup exceeded a critical limit, the sheet was ejected mechanically from the squeezed X-point area. The reconnection (outflow) speed was slow during the flux pileup and was fast during the ejection, indicating that intermittent reconnection similar to the solar flare increased the averaged reconnection speed. These transient effects enable us to have the fast reconnection as well as the high-power reconnection heating, even if the merging high-q tokamaks have low current-sheet resistivity. (author)

  20. Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

    Energy Technology Data Exchange (ETDEWEB)

    Tournassat, Christophe, E-mail: c.tournassat@brgm.fr [BRGM, French Geological Survey, Orleans (France); Alt-Epping, Peter [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland); Gaucher, Eric C. [BRGM, French Geological Survey, Orleans (France); Gimmi, Thomas [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland)] [Laboratory for Waste Management, Paul Scherrer Institut, Villigen (Switzerland); Leupin, Olivier X. [NAGRA, CH-5430 Wettingen (Switzerland); Wersin, Paul [Gruner Ltd., CH-4020 Basel (Switzerland)

    2011-06-15

    Highlights: > Reactive transport modelling was used to simulate simultaneously solute transport, thermodynamic reactions, ion exchange and biodegradation during an in-situ experiment in a clay-rock formation. > Opalinus clay formation has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. > Buffering capacity is mainly attributed to the carbonate system and to the reactivity of clay surfaces (cation exchange, pH buffering). - Abstract: Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C, dissolved inorganic C and SO{sub 4} concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of

  1. Experiments in ZED-2 to study the physics of low-void reactivity fuel in CANDU

    International Nuclear Information System (INIS)

    Zeller, M.B.; Celli, A.; McPhee, G.P.

    1994-01-01

    Prospective CANDU clients have indicated a desire for a zero or negative coolant void reactivity. In response to this market requirement AECL Research and AECL CANDU are jointly developing and testing a Low-Void Reactivity Fuel (LVRF) bundle, which will be retrofitable to the current generation of CANDU reactors. An important component of the LVRF program is the undertaking of reactor-physics experiments in the zero-energy ZED-2 lattice test facility at Chalk River Laboratories. Preliminary void-reactivity measurements have already been performed in ZED-2 using a limited amount of the prototype fuel. These experiments were to provide a proof-of-principle for the LVRF concept. A more comprehensive set of experiments are planned for later this year. Experiments to be performed include: measuring the critical buckling of CANDU-type lattices containing LVRF, with and without coolant in the channels; measuring the reactivity effect of heating the LVRF fuel and coolant in ZED-2 hot channels; and measuring detailed reaction rates and neutron density distributions across a LVRF bundle, in voided and D 2 O-cooled channels, by the foil activation method. This paper describes the experimental approach to be used for the study and presents calculations employing transport and diffusion theory to predict the results. The codes used for the simulations are the lattice code WIMS-AECL and the core code CONIFERS. Included in the paper are results from the preliminary measurement of void coefficient for LVRF in a ZED-2 lattice and a comparison of those results to predictions based on WIMS-AECL calculations. (author). 3 refs., 1 tab., 10 figs

  2. Boron dilution transients during natural circulation flow in PWR-Experiments and CFD simulations

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, Thomas [Forschungszentrum Dresden-Rossendorf (FZD)-Institute of Safety Research, P.O. Box 510119, D-01314 Dresden (Germany)], E-mail: T.Hoehne@fzd.de; Kliem, Soeren; Rohde, Ulrich; Weiss, Frank-Peter [Forschungszentrum Dresden-Rossendorf (FZD)-Institute of Safety Research, P.O. Box 510119, D-01314 Dresden (Germany)

    2008-08-15

    Coolant mixing in the cold leg, downcomer and the lower plenum of pressurized water reactors is an important phenomenon mitigating the reactivity insertion into the core. Therefore, mixing of the de-borated slugs with the ambient coolant in the reactor pressure vessel was investigated at the four loops 1:5 scaled Rossendorf coolant mixing model (ROCOM) mixing test facility. In particular thermal hydraulics analyses have shown, that weakly borated condensate can accumulate in the pump loop seal of those loops, which do not receive a safety injection. After refilling of the primary circuit, natural circulation in the stagnant loops can re-establish simultaneously and the de-borated slugs are shifted towards the reactor pressure vessel (RPV). In the ROCOM experiments, the length of the flow ramp and the initial density difference between the slugs and the ambient coolant was varied. From the test matrix experiments with 0 resp. 2% density difference between the de-borated slugs and the ambient coolant were used to validate the CFD software ANSYS CFX. To model the effects of turbulence on the mean flow a higher order Reynolds stress turbulence model was employed and a mesh consisting of 6.4 million hybrid elements was utilized. Only the experiments and CFD calculations with modeled density differences show stratification in the downcomer. Depending on the degree of density differences the less dense slugs flow around the core barrel at the top of the downcomer. At the opposite side, the lower borated coolant is entrained by the colder safety injection water and transported to the core. The validation proves that ANSYS CFX is able to simulate appropriately the flow field and mixing effects of coolant with different densities.

  3. Numerical simulation of CALIBAN reactivity perturbation experiments using neptunium-237 samples

    International Nuclear Information System (INIS)

    Humbert, Philippe; Mechitoua, Boukhmes

    2003-01-01

    In order to contribute to the validation of nuclear data used in critical mass computation, reactivity perturbation experiments using 237 Np samples have been performed at CEA-Valduc using the fast pulsed reactor CALIBAN operated in continuous mode. In this paper we report these experiments together with the numerical calculations. The calculations were carried out using PANDA, a S N code developed at CEA-Bruyeres-le-Chatel for classic criticality and stochastic neutronics applications and with MCNP4C which is a commonly used Monte Carlo code. A good agreement was found between experimental and deterministic results. (author)

  4. Transient analyzer

    International Nuclear Information System (INIS)

    Muir, M.D.

    1975-01-01

    The design and design philosophy of a high performance, extremely versatile transient analyzer is described. This sub-system was designed to be controlled through the data acquisition computer system which allows hands off operation. Thus it may be placed on the experiment side of the high voltage safety break between the experimental device and the control room. This analyzer provides control features which are extremely useful for data acquisition from PPPL diagnostics. These include dynamic sample rate changing, which may be intermixed with multiple post trigger operations with variable length blocks using normal, peak to peak or integrate modes. Included in the discussion are general remarks on the advantages of adding intelligence to transient analyzers, a detailed description of the characteristics of the PPPL transient analyzer, a description of the hardware, firmware, control language and operation of the PPPL transient analyzer, and general remarks on future trends in this type of instrumentation both at PPPL and in general

  5. Reactivity to Social Stress in Subclinical Social Anxiety: Emotional Experience, Cognitive Appraisals, Behavior, and Physiology

    Science.gov (United States)

    Crişan, Liviu G.; Vulturar, Romana; Miclea, Mircea; Miu, Andrei C.

    2016-01-01

    Recent research indicates that subclinical social anxiety is associated with dysfunctions at multiple psychological and biological levels, in a manner that seems reminiscent of social anxiety disorder (SAD). This study aimed to describe multidimensional responses to laboratory-induced social stress in an analog sample selected for social anxiety symptoms. State anxiety, cognitive biases related to negative social evaluation, speech anxiety behaviors, and cortisol reactivity were assessed in the Trier Social Stress Test (TSST). Results showed that social anxiety symptoms were associated with increased state anxiety, biased appraisals related to the probability and cost of negative social evaluations, behavioral changes in facial expression that were consistent with speech anxiety, and lower cortisol reactivity. In addition, multiple interrelations between responses in the TSST were found, with positive associations between subjective experience, cognitive appraisals, and observable behavior, as well as negative associations between each of the former two types of response and cortisol reactivity. These results show that in response to social stressors, subclinical social anxiety is associated with significant changes in emotional experience, cognitive appraisals, behaviors, and physiology that could parallel those previously found in SAD samples. PMID:26858658

  6. Method of analysis to determine subcritical reactivity from the pulsed neutron experiment

    International Nuclear Information System (INIS)

    Parks, P.B.

    1975-06-01

    The published methods for the deduction of reactivity from pulsed neutron experiments on subcritical reactors are reviewed. Each method is categorized as inherently yielding a result that is either spatially independent or spatially dependent. The spatially independent results are formally identical with the static reactivity; the result does not depend, in principle, on the location of either the pulsed neutron source or the neutron detector during data collection. The spatially dependent results only approximate the static reactivity; the results are affected, in varying degrees, by the locations of the source and detector. Among the techniques yielding spatially independent results are the Space-Time method of Parks and Stewart and the Inhour method of Preskitt et al. Spatially dependent results are obtained with the Sjoestrand, Gozani, and Garelis-Russell methods which are examined with and without the kinetic distortion corrections given by Becker and Quisenberry. Intercomparisons of all methods are made with reference to pulsed neutron experiments on both unreflected and reflected reactors. Recommendations are made concerning the best choice of method under the various experimental conditions that are likely to be encountered. 14 references. (U.S.)

  7. Poison 1 - a programme for calculation of reactivity transients due to fission product poisoning and its application in continuous determination of xenon and samarium poisoning in reactor KS-150

    International Nuclear Information System (INIS)

    Rana, S.B.

    1973-12-01

    The report contains a user's description of the 3-dimensional programme POISON 1 for calculating reactivity transients due to fission-product poisoning during changes of reactor power. The chapter dealing with Xe poisoning contains a description of Xe tables, the method of operational determination of Xe poisoning, use of Xe transients for calibrating control rods and means of shutting down the reactor without being overriden by Xe poisoning. Sm poisoning is determined continuously on the basis of the power diagram of reactor operation. In conclusion a possibility of using the programme in a process computer in combination with self-powered detectors as local power sensors is indicated. (author)

  8. Investigation of reactivity between SiC and Nb-1Zr in planned irradiation creep experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lewinsohn, C.A.; Hamilton, M.L.; Jones, R.H.

    1997-08-01

    Thermodynamic calculations and diffusion couple experiments showed that SiC and Nb-1Zr were reactive at the upper range of temperatures anticipated in the planned irradiation creep experiment. Sputter-deposited aluminum oxide (Al{sub 2}O{sub 3}) was selected as a diffusion barrier coating. Experiments showed that although the coating coarsened at high temperature it was an effective barrier for diffusion of silicon from SiC into Nb-1Zr. Therefore, to avoid detrimental reactions between the SiC composite and the Nb-1Zr pressurized bladder during the planned irradiation creep experiment, a coating of Al{sub 2}O{sub 3} will be required on the Nb-1Zr bladder.

  9. Elucidating reactivity regimes in cyclopentane oxidation: Jet stirred reactor experiments, computational chemistry, and kinetic modeling

    KAUST Repository

    Rachidi, Mariam El; Thion, Sé bastien; Togbé , Casimir; Dayma, Guillaume; Mehl, Marco; Dagaut, Philippe; Pitz, William J.; Zá dor, Judit; Sarathy, Mani

    2016-01-01

    This study is concerned with the identification and quantification of species generated during the combustion of cyclopentane in a jet stirred reactor (JSR). Experiments were carried out for temperatures between 740 and 1250K, equivalence ratios from 0.5 to 3.0, and at an operating pressure of 10atm. The fuel concentration was kept at 0.1% and the residence time of the fuel/O/N mixture was maintained at 0.7s. The reactant, product, and intermediate species concentration profiles were measured using gas chromatography and Fourier transform infrared spectroscopy. The concentration profiles of cyclopentane indicate inhibition of reactivity between 850-1000K for ϕ = 2.0 and ϕ = 3.0. This behavior is interesting, as it has not been observed previously for other fuel molecules, cyclic or non-cyclic. A kinetic model including both low- and high-temperature reaction pathways was developed and used to simulate the JSR experiments. The pressure-dependent rate coefficients of all relevant reactions lying on the PES of cyclopentyl+O, as well as the C-C and C-H scission reactions of the cyclopentyl radical were calculated at the UCCSD(T)-F12b/cc-pVTZ-F12//M06-2X/6-311++G(d,p) level of theory. The simulations reproduced the unique reactivity trend of cyclopentane and the measured concentration profiles of intermediate and product species. Sensitivity and reaction path analyses indicate that this reactivity trend may be attributed to differences in the reactivity of allyl radical at different conditions, and it is highly sensitive to the C-C/C-H scission branching ratio of the cyclopentyl radical decomposition.

  10. Elucidating reactivity regimes in cyclopentane oxidation: Jet stirred reactor experiments, computational chemistry, and kinetic modeling

    KAUST Repository

    Rachidi, Mariam El

    2016-06-23

    This study is concerned with the identification and quantification of species generated during the combustion of cyclopentane in a jet stirred reactor (JSR). Experiments were carried out for temperatures between 740 and 1250K, equivalence ratios from 0.5 to 3.0, and at an operating pressure of 10atm. The fuel concentration was kept at 0.1% and the residence time of the fuel/O/N mixture was maintained at 0.7s. The reactant, product, and intermediate species concentration profiles were measured using gas chromatography and Fourier transform infrared spectroscopy. The concentration profiles of cyclopentane indicate inhibition of reactivity between 850-1000K for ϕ = 2.0 and ϕ = 3.0. This behavior is interesting, as it has not been observed previously for other fuel molecules, cyclic or non-cyclic. A kinetic model including both low- and high-temperature reaction pathways was developed and used to simulate the JSR experiments. The pressure-dependent rate coefficients of all relevant reactions lying on the PES of cyclopentyl+O, as well as the C-C and C-H scission reactions of the cyclopentyl radical were calculated at the UCCSD(T)-F12b/cc-pVTZ-F12//M06-2X/6-311++G(d,p) level of theory. The simulations reproduced the unique reactivity trend of cyclopentane and the measured concentration profiles of intermediate and product species. Sensitivity and reaction path analyses indicate that this reactivity trend may be attributed to differences in the reactivity of allyl radical at different conditions, and it is highly sensitive to the C-C/C-H scission branching ratio of the cyclopentyl radical decomposition.

  11. Reactivity worth measurements on the CALIBAN reactor: interpretation of integral experiments for the nuclear data validation

    International Nuclear Information System (INIS)

    Richard, B.

    2012-01-01

    The good knowledge of nuclear data, input parameters for the neutron transport calculation codes, is necessary to support the advances of the nuclear industry. The purpose of this work is to bring pertinent information regarding the nuclear data integral validation process. Reactivity worth measurements have been performed on the Caliban reactor, they concern four materials of interest for the nuclear industry: gold, lutetium, plutonium and uranium 238. Experiments which have been conducted in order to improve the characterization of the core are also described and discussed, the latter are necessary to the good interpretation of reactivity worth measurements. The experimental procedures are described with their associated uncertainties, measurements are then compared to numerical results. The methods used in numerical calculations are reported, especially the multigroup cross sections generation for deterministic codes. The modeling of the experiments is presented along with the associated uncertainties. This comparison led to an interpretation concerning the qualification of nuclear data libraries. Discrepancies are reported, discussed and justify the need of such experiments. (author) [fr

  12. The behaviour of irradiated fuel under RIA transients: Interpretation of the CABRI experiments

    International Nuclear Information System (INIS)

    Papin, J.; Rigat, H.; Breton, J.P.; Schmitz, F.

    1996-01-01

    Paper presents the results of investigation of highly irradiated PWR fuel behaviour under fast power transients conducted in a sodium loop of CABRI reactor, as well as the results on development and validation of computer code SCANAIR. (author). 8 refs, 9 figs, 2 tabs

  13. Instrumented anvil-on-rod impact experiments for validating constitutive strength model for simulating transient dynamic deformation response of metals

    International Nuclear Information System (INIS)

    Martin, M.; Shen, T.; Thadhani, N.N.

    2008-01-01

    Instrumented anvil-on-rod impact experiments were performed to access the applicability of this approach for validating a constitutive strength model for dynamic, transient-state deformation and elastic-plastic wave interactions in vanadium, 21-6-9 stainless steel, titanium, and Ti-6Al-4V. In addition to soft-catching the impacted rod-shaped samples, their transient deformation states were captured by high-speed imaging, and velocity interferometry was used to record the sample back (free) surface velocity and monitor elastic-plastic wave interactions. Simulations utilizing AUTODYN-2D hydrocode with Steinberg-Guinan constitutive equation were used to generate simulated free surface velocity traces and final/transient deformation profiles for comparisons with experiments. The simulations were observed to under-predict the radial strain for bcc vanadium and fcc steel, but over-predict the radial strain for hcp titanium and Ti-6Al-4V. The correlations illustrate the applicability of the instrumented anvil-on-rod impact test as a method for providing robust model validation based on the entire deformation event, and not just the final deformed state

  14. Reactive transport modelling of a heating and radiation experiment in the Boom clay (Belgium)

    International Nuclear Information System (INIS)

    Montenegro, L.; Samper, J.; Delgado, J.

    2003-01-01

    Most countries around the world consider Deep Geological Repositories (DGR) as the most safe option for the final disposal of high level radioactive waste (HLW). DGR is based on adopting a system of multiple barriers between the HLW and the biosphere. Underground laboratories provide information about the behaviour of these barriers at real conditions. Here we present a reactive transport model for the CERBERUS experiment performed at the HADES underground laboratory at Mol (Belgium) in order to characterize the thermal (T), hydrodynamic (H) and geochemical (G) behaviour of the Boon clay. This experiment is unique because it addresses the combined effect of heat and radiation produced by the storage of HLW in a DGR. Reactive transport models which are solved with CORE, are used to perform quantitative predictions of Boom clay thermo-hydro-geochemical (THG) behaviour. Numerical results indicate that heat and radiation cause a slight oxidation near of the radioactive source, pyrite dissolution, a pH decrease and slight changes in the pore water chemical composition of the Boom clay. (Author) 33 refs

  15. Transient heat loads in current fusion experiments, extrapolation to ITER and consequences for its operation

    International Nuclear Information System (INIS)

    Loarte, A; Saibene, G; Sartori, R; Riccardo, V; Andrew, P; Paley, J; Fundamenski, W; Eich, T; Herrmann, A; Pautasso, G; Kirk, A; Counsell, G; Federici, G; Strohmayer, G; Whyte, D; Leonard, A; Pitts, R A; Landman, I; Bazylev, B; Pestchanyi, S

    2007-01-01

    New experimental results on transient loads during ELMs and disruptions in present divertor tokamaks are described and used to carry out a extrapolation to ITER reference conditions and to draw consequences for its operation. In particular, the achievement of low energy/convective type I edge localized modes (ELMs) in ITER-like plasma conditions seems the only way to obtain transient loads which may be compatible with an acceptable erosion lifetime of plasma facing components (PFCs) in ITER. Power loads during disruptions, on the contrary, seem to lead in most cases to an acceptable divertor lifetime because of the relatively small plasma thermal energy remaining at the thermal quench and the large broadening of the power flux footprint during this phase. These conclusions are reinforced by calculations of the expected erosion lifetime, under these load conditions, which take into account a realistic temporal dependence of the power fluxes on PFCs during ELMs and disruptions

  16. Transient Mathematical Modeling for Liquid Rocket Engine Systems: Methods, Capabilities, and Experience

    Science.gov (United States)

    Seymour, David C.; Martin, Michael A.; Nguyen, Huy H.; Greene, William D.

    2005-01-01

    The subject of mathematical modeling of the transient operation of liquid rocket engines is presented in overview form from the perspective of engineers working at the NASA Marshall Space Flight Center. The necessity of creating and utilizing accurate mathematical models as part of liquid rocket engine development process has become well established and is likely to increase in importance in the future. The issues of design considerations for transient operation, development testing, and failure scenario simulation are discussed. An overview of the derivation of the basic governing equations is presented along with a discussion of computational and numerical issues associated with the implementation of these equations in computer codes. Also, work in the field of generating usable fluid property tables is presented along with an overview of efforts to be undertaken in the future to improve the tools use for the mathematical modeling process.

  17. Observations of variable and transient X-ray sources with the Ariel V Sky Survey Experiment

    International Nuclear Information System (INIS)

    Pounds, K.A.; Cooke, B.A.; Ricketts, M.J.; Turner, M.J.; Peacock, A.; Eadie, G.

    1976-01-01

    Results obtained during the first six months in orbit of Aerial V with the Leicester Sky Survey are reviewed. Among 80 sources found by a scan of the Milky Way, 16 are new, and 11 UHURU sources in the scanned region are not detected. Some of these sources may be transient. The light curve of Cen X-3 in a binary cycle shows a dip between phase 0.5 and 0.75, and a secondary maximum at the centre of the dip. The dip and the maximum get progressively weaker in the succeeding cycles. These features are interpreted in terms of the stellar wind accretion model. Cyg X-1 observation for 14 days gives a broad minimum around superior conjunction. Four bright transient sources of nova-like light curves have been observed. The light curves and the spectra are given for TrA X-1 (A1524-62) and Tau X-T (A0535+26). (Auth.)

  18. Modelling of power-reactivity coefficient measurement

    International Nuclear Information System (INIS)

    Strmensky, C.; Petenyi, V.; Jagrik, J.; Minarcin, M.; Hascik, R.; Toth, L.

    2005-01-01

    Report describes results of modeling of power-reactivity coefficient analysis on power-level. In paper we calculate values of discrepancies arisen during transient process. These discrepancies can be arisen as result of experiment evaluation and can be caused by disregard of 3D effects on neutron distribution. The results are critically discussed (Authors)

  19. Segregated copper ratio experiment on transient stability (SeCRETS). Final Report

    International Nuclear Information System (INIS)

    Bruzzone, P.

    2001-01-01

    Two Nb 3 Sn, steel jacketed, cable-in-conduit conductors have been manufactured with identical non-Cu cross sections and the stabilizer either included in the Nb 3 Sn composite or partly segregated as copper wires. The two conductors are series connected and wound as a bifilar , single layer solenoid, assembled in the high field bore (11 T) of the SULTAN test facility. The operating current is up to 12 kA (400 A/mm 2 ). A transverse pulsed field is applied with ΔB up to 2.7 T, field rate up to 180 T/s and field integral up to 530 T 2 /s. In the dc test, a good agreement is found between the I c and the T cs results, both correctly scaling according to the parameters derived from the strand tests. The n-value from the V-I curve is in the range of 15. The current sharing at the high field section is correlated with a local current re-distribution, observed by arrays of miniature Hall sensors, detecting the self-field around the conductor. The ac losses results in the range of 2 to 9 Hz by gas flow calorimetry indicate coupling currents constant, nτ, in the range of 1.5 ms at high field, increasing by a factor of 2 with 12 kA transport current. Loss extrapolation to 0 frequency suggests that the loss curve may be not linear outside the test range, with higher nτ at lower field rate. The calorimetric loss estimation at the fast field transient (f=15 Hz) indicates nτ ≅ 2 ms. The ITER plasma disruption transients have been reproduced by the pulsed coils. Due to the very low ac losses, no quench could be generated in either conductor even reducing the temperature margin below 0.2-0.3 K. Very large field transients, with integral above 100 T 2 /s, are required to quench the conductors. In that range, the conductor without segregated copper has superior performance. Due to the large interstrand resistance (very low ac losses), the segregated copper has marginal contribution to the stability. No evidence of current redistribution is observed during the field transients

  20. Segregated copper ratio experiment on transient stability (SeCRETS). Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bruzzone, P. [ed.] [Ecole Polytechnique Federale de Lausanne, Centre de Recherches en Physique des Plasmas (CRPP), CH-1015 Lausanne (Switzerland)

    2001-01-01

    Two Nb{sub 3}Sn, steel jacketed, cable-in-conduit conductors have been manufactured with identical non-Cu cross sections and the stabilizer either included in the Nb{sub 3}Sn composite or partly segregated as copper wires. The two conductors are series connected and wound as a bifilar , single layer solenoid, assembled in the high field bore (11 T) of the SULTAN test facility. The operating current is up to 12 kA (400 A/mm{sup 2}). A transverse pulsed field is applied with {delta}B up to 2.7 T, field rate up to 180 T/s and field integral up to 530 T{sup 2}/s. In the dc test, a good agreement is found between the I{sub c} and the T{sub cs} results, both correctly scaling according to the parameters derived from the strand tests. The n-value from the V-I curve is in the range of 15. The current sharing at the high field section is correlated with a local current re-distribution, observed by arrays of miniature Hall sensors, detecting the self-field around the conductor. The ac losses results in the range of 2 to 9 Hz by gas flow calorimetry indicate coupling currents constant, n{tau}, in the range of 1.5 ms at high field, increasing by a factor of 2 with 12 kA transport current. Loss extrapolation to 0 frequency suggests that the loss curve may be not linear outside the test range, with higher n{tau} at lower field rate. The calorimetric loss estimation at the fast field transient (f=15 Hz) indicates n{tau} {approx_equal} 2 ms. The ITER plasma disruption transients have been reproduced by the pulsed coils. Due to the very low ac losses, no quench could be generated in either conductor even reducing the temperature margin below 0.2-0.3 K. Very large field transients, with integral above 100 T{sup 2}/s, are required to quench the conductors. In that range, the conductor without segregated copper has superior performance. Due to the large interstrand resistance (very low ac losses), the segregated copper has marginal contribution to the stability. No evidence of current

  1. Variably Saturated Flow and Multicomponent Biogeochemical Reactive Transport Modeling of a Uranium Bioremediation Field Experiment

    International Nuclear Information System (INIS)

    Yabusaki, Steven B.; Fang, Yilin; Williams, Kenneth H.; Murray, Christopher J.; Ward, Anderson L.; Dayvault, Richard; Waichler, Scott R.; Newcomer, Darrell R.; Spane, Frank A.; Long, Philip E.

    2011-01-01

    Field experiments at a former uranium mill tailings site have identified the potential for stimulating indigenous bacteria to catalyze the conversion of aqueous uranium in the +6 oxidation state to immobile solid-associated uranium in the +4 oxidation state. This effectively removes uranium from solution resulting in groundwater concentrations below actionable standards. Three-dimensional, coupled variably-saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport rates and biogeochemical reaction rates that determine the location and magnitude of key reaction products. A comprehensive reaction network, developed largely through previous 1-D modeling studies, was used to simulate the impacts on uranium behavior of pulsed acetate amendment, seasonal water table variation, spatially-variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. A principal challenge is the mechanistic representation of biologically-mediated terminal electron acceptor process (TEAP) reactions whose products significantly alter geochemical controls on uranium mobility through increases in pH, alkalinity, exchangeable cations, and highly reactive reduction products. In general, these simulations of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado confirmed previously identified behaviors including (1) initial dominance by iron reducing bacteria that concomitantly reduce aqueous U(VI), (2) sulfate reducing bacteria that become dominant after ∼30 days and outcompete iron reducers for the acetate electron donor, (3) continuing iron-reducer activity and U(VI) bioreduction during dominantly sulfate reducing conditions, and (4) lower apparent U(VI) removal from groundwater during dominantly sulfate reducing conditions. New knowledge on simultaneously active metal and sulfate reducers has been

  2. Improved Reactive Flow Modeling of the LX-17 Double Shock Experiments

    Science.gov (United States)

    Rehagen, Thomas J.; Vitello, Peter

    2017-06-01

    Over driven double shock experiments provide a measurement of the properties of the reaction product states of the insensitive high explosive LX-17 (92.5% TATB and 7.5% Kel-F by weight). These experiments used two flyer materials mounted on the end of a projectile to send an initial shock through the LX-17, followed by a second shock of a higher magnitude into the detonation products. In the experiments, the explosive was initially driven by the flyer plate to pressures above the Chapman-Jouguet state. The particle velocity history was recorded by Photonic Doppler Velocimetry (PDV) probes pointing at an aluminum foil coated LiF window. The PDV data shows a sharp initial shock and decay, followed by a rounded second shock. Here, the experimental results are compared to 2D and 3D Cheetah reactive flow modeling. Our default Cheetah reactive flow model fails to accurately reproduce the decay of the first shock or the curvature or strength of the second shock. A new model is proposed in which the carbon condensate produced in the reaction zone is controlled by a kinetic rate. This allows the carbon condensate to be initially out of chemical equilibrium with the product gas. This new model reproduces the initial detonation peak and decay, and matches the curvature of the second shock, however, it still over-predicts the strength of the second shock. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  3. Localized reactive flow in carbonate rocks: Core-flood experiments and network simulations

    Science.gov (United States)

    Wang, Haoyue; Bernabé, Yves; Mok, Ulrich; Evans, Brian

    2016-11-01

    We conducted four core-flood experiments on samples of a micritic, reef limestone from Abu Dhabi under conditions of constant flow rate. The pore fluid was water in equilibrium with CO2, which, because of its lowered pH, is chemically reactive with the limestone. Flow rates were between 0.03 and 0.1 mL/min. The difference between up and downstream pore pressures dropped to final values ≪1 MPa over periods of 3-18 h. Scanning electron microscope and microtomography imaging of the starting material showed that the limestone is mostly calcite and lacks connected macroporosity and that the prevailing pores are few microns large. During each experiment, a wormhole formed by localized dissolution, an observation consistent with the decreases in pressure head between the up and downstream reservoirs. Moreover, we numerically modeled the changes in permeability during the experiments. We devised a network approach that separated the pore space into competing subnetworks of pipes. Thus, the problem was framed as a competition of flow of the reactive fluid among the adversary subnetworks. The precondition for localization within certain time is that the leading subnetwork rapidly becomes more transmissible than its competitors. This novel model successfully simulated features of the shape of the wormhole as it grew from few to about 100 µm, matched the pressure history patterns, and yielded the correct order of magnitude of the breakthrough time. Finally, we systematically studied the impact of changing the statistical parameters of the subnetworks. Larger mean radius and spatial correlation of the leading subnetwork led to faster localization.

  4. C-reactive protein predicts further ischemic events in first-ever transient ischemic attack or stroke patients with intracranial large-artery occlusive disease.

    Science.gov (United States)

    Arenillas, Juan F; Alvarez-Sabín, José; Molina, Carlos A; Chacón, Pilar; Montaner, Joan; Rovira, Alex; Ibarra, Bernardo; Quintana, Manuel

    2003-10-01

    The role of inflammation in intracranial large-artery occlusive disease is unclear. We sought to investigate the relationship between high-sensitivity C-reactive protein (CRP) levels and the risk of further ischemic events in first-ever transient ischemic attack (TIA) or stroke patients with intracranial large-artery occlusive disease. Of a total of 127 consecutive first-ever TIA or ischemic stroke patients with intracranial stenoses detected by transcranial Doppler ultrasonography, 71 fulfilled all inclusion criteria, which included angiographic confirmation. Serum high-sensitivity CRP level was determined a minimum of 3 months after the qualifying event. Patients were followed up during 1 year after blood sampling. Thirteen patients (18.3%) with intracranial large-artery occlusive disease experienced an end point event: 9 cerebral ischemic events, 7 of which were attributable to intracranial large-artery occlusive disease, and 4 myocardial infarctions. Patients in the highest quintile of high-sensitivity CRP level had a significantly higher adjusted odds ratio for new events compared with those in the first quintile (odds ratio, 8.66; 95% CI, 1.39 to 53.84; P=0.01). A high-sensitivity CRP level above the receiver operating characteristic curve cutoff value of 1.41 mg/dL emerged as an independent predictor of new end point events (hazard ratio, 7.14; 95% CI, 1.77 to 28.73; P=0.005) and of further intracranial large-artery occlusive disease-related ischemic events (hazard ratio, 30.67; 95% CI, 3.6 to 255.5; P=0.0015), after adjustment for age, sex, and risk factors. Kaplan-Meier curves showed that a significantly lower proportion of patients with a high-sensitivity CRP >1.41 mg/dL remained free of a new ischemic event (P<0.0001). High-sensitivity CRP serum level predicts further intracranial large-artery occlusive disease-related and any major ischemic events in patients with first-ever TIA or stroke with intracranial large-artery occlusive disease. These findings

  5. Comparison of empirical transport models with transient transport experiments in LHD

    International Nuclear Information System (INIS)

    Yakovlev, Mikhail; Inagaki, Shigeru; Ida, Katsumi

    2004-01-01

    A study of the electron transport in helical plasma of Large Helical Device (LHD) has been performed using a perturbation to an equilibrium state. The periodic perturbation in plasma is induced by on-axis Electron Cyclotron Heating (ECH) modulated signal for different temperatures of plasma electron. The experimental data are compared with results from simulation within framework of the diffusive model with additional convective term. The convection heat flux is introduced to describe the heat propagation in LHD. It has been shown that the dynamic plasma heat diffusivity coefficient χ e estimated from the transient analysis becomes larger with increasing electron temperature in LHD plasma. (author)

  6. Operating experience with high beam currents and transient beam loading in the SLC damping rings

    International Nuclear Information System (INIS)

    Minty, M.G.; Akre, R.; Krejcik, P.; Siemann, R.H.

    1995-01-01

    During the 1994 SLC run the nominal operating intensity in the damping rings was raised from 3.5 x 10 10 to greater than 4 x 10 10 particles per bunch (ppb). Stricter regulation of rf system parameters was required to maintain stability of the rf system and particle beam. Improvements were made in the feedback loops which control the cavity amplitude and loading angles. Compensation for beam loading was also required to prevent klystron saturation during repetition rate changes. To minimize the effects of transient loading on the rf system, the gain of the direct rf feedback loop and the loading angles were optimized

  7. Reactive flow modeling of small scale detonation failure experiments for a baseline non-ideal explosive

    Energy Technology Data Exchange (ETDEWEB)

    Kittell, David E.; Cummock, Nick R.; Son, Steven F. [School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2016-08-14

    Small scale characterization experiments using only 1–5 g of a baseline ammonium nitrate plus fuel oil (ANFO) explosive are discussed and simulated using an ignition and growth reactive flow model. There exists a strong need for the small scale characterization of non-ideal explosives in order to adequately survey the wide parameter space in sample composition, density, and microstructure of these materials. However, it is largely unknown in the scientific community whether any useful or meaningful result may be obtained from detonation failure, and whether a minimum sample size or level of confinement exists for the experiments. In this work, it is shown that the parameters of an ignition and growth rate law may be calibrated using the small scale data, which is obtained from a 35 GHz microwave interferometer. Calibration is feasible when the samples are heavily confined and overdriven; this conclusion is supported with detailed simulation output, including pressure and reaction contours inside the ANFO samples. The resulting shock wave velocity is most likely a combined chemical-mechanical response, and simulations of these experiments require an accurate unreacted equation of state (EOS) in addition to the calibrated reaction rate. Other experiments are proposed to gain further insight into the detonation failure data, as well as to help discriminate between the role of the EOS and reaction rate in predicting the measured outcome.

  8. Analysis of molten fuel-coolant interaction during a reactivity-initiated accident experiment

    International Nuclear Information System (INIS)

    El-Genk, M.S.; Hobbins, R.R.

    1981-01-01

    The results of a reactivity-initiated accident experiment, designated RIA-ST-4, are discussed and analyzed with regard to molten fuel-coolant interaction (MFCI). In this experiment, extensive amounts of molten UO 2 fuel and zircaloy cladding were produced and fragmented upon mixing with the coolant. Coolant pressurization up to 35 MPa and coolant overheating in excess of 940 K occurred after fuel rod failure. The initial coolant conditions were similar to those in boiling water reactors during a hot startup (that is, coolant pressure of 6.45 MPa, coolant temperature of 538 K, and coolant flow rate of 85 cm 3 /s). It is concluded that the high coolant pressure recorded in the RIA-ST-4 experiment was caused by an energetic MFCI and was not due to gas release from the test rod at failure, Zr/water reaction, or to UO 2 fuel vapor pressure. The high coolant temperature indicated the presence of superheated steam, which may have formed during the expansion of the working fluid back to the initial coolant pressure; yet, the thermal-to-mechanical energy conversion ratio is estimated to be only 0.3%

  9. Reactive Halogens in the Marine Boundary Layer (RHaMBLe: the tropical North Atlantic experiments

    Directory of Open Access Journals (Sweden)

    J. D. Lee

    2010-02-01

    Full Text Available The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period.

    This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental. Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv (note the non-IUPAC adoption in this manuscript of pptv and ppbv, equivalent to pmol mol−1 and nmol mol−1 to reflect common practice. Consistency with

  10. 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

  11. Recent experience related to neutronic transients in Ontario Hydro CANDU nuclear generating stations

    International Nuclear Information System (INIS)

    Frescura, G.M.; Smith, A.J.; Lau, J.H.

    1991-01-01

    Ontario Hydro presently operates 18 CANDU reactors in the province of Ontario, Canada. All of these reactors are of the CANDU Pressurized Heavy Water design, although their design features differ somewhat reflecting the evolution that has taken place from 1971 when the first Pickering unit started operation to the present as the Darlington units are being placed in service. Over the last three years, two significant neutronic transients took place at the Pickering Nuclear Generating Station 'A' (NGS A) one of which resulted in a number of fuel failures. Both events provided valuable lessons in the areas of operational safety, fuel performance And accident analysis. The events and the lessons learned are discussed in this paper

  12. Investigation of the Buckling-Reactivity Conversion Coefficient using SRAC and MVP codes for UO2 Lattices in TCA experiments

    International Nuclear Information System (INIS)

    Le Dai Dien

    2008-01-01

    Benchmark experiments for International Reactor Physics Benchmark Experiments (IRPhE) Project carried out at TCA, the temperature effects on reactivity were studied for light water moderated and reflected UO 2 cores with/without soluble poisons. The buckling coefficient method using the measured critical water levels was proposed by Suzaki et al. The temperature dependence of buckling coefficient of reactivity and its variance by the core configurations of the benchmark experiments was investigated using SRAC and MVP calculations. From the calculations by SRAC as well as by MVP it is seen that the K-value can be taken as an average value only for each core with temperature changes which are considered as perturbation parameter. The difference between our calculations and benchmark results which uses constant K-value for all cores proves that the results depend on K-value and it play important role in defining reactivity effect using the water level worth method. (author)

  13. Detailed characterizations of a Comparative Reactivity Method (CRM) instrument: experiments vs. modelling

    Science.gov (United States)

    Michoud, V.; Hansen, R. F.; Locoge, N.; Stevens, P. S.; Dusanter, S.

    2015-04-01

    simple chemical mechanism, taking into account the inorganic chemistry from IUPAC 2001 and a simple organic chemistry scheme including only a generic RO2 compounds for all oxidized organic trace gases; and (2) a more exhaustive chemical mechanism, based on the Master Chemical Mechanism (MCM), including the chemistry of the different trace gases used during laboratory experiments. Both mechanisms take into account self- and cross-reactions of radical species. The simulations using these mechanisms allow reproducing the magnitude of the corrections needed to account for NO interferences and a deviation from pseudo first-order kinetics, as well as their dependence on the Pyrrole-to-OH ratio and on bimolecular reaction rate constants of trace gases. The reasonable agreement found between laboratory experiments and model simulations gives confidence in the parameterizations proposed to correct the Total OH reactivity measured by CRM. However, it must be noted that the parameterizations presented in this paper are suitable for the CRM instrument used during the laboratory characterization and may be not appropriate for other CRM instruments, even if similar behaviours should be observed. It is therefore recommended that each group characterizes its own instrument following the recommendations given in this study. Finally, the assessment of the limit of detection and total uncertainties is discussed and an example of field deployment of this CRM instrument is presented.

  14. The reactive solid-gas flow of a fluidized bed for UO2 conversion

    International Nuclear Information System (INIS)

    Juanico, L.E.

    1991-01-01

    The reactive solid-gas flow of a fluidized bed for UO 2 conversion was modeled. The sedimentation-reaction process was treated using the drift-flux equations. Also, the associated pressure transient due to the reaction gas release was analyzed. An experiment was carried out to compare the results, and pressure transient was numerically simulated, reaching interesting conclusions. (Author) [es

  15. porewater chemistry experiment at Mont Terri rock laboratory. Reactive transport modelling including bacterial activity

    International Nuclear Information System (INIS)

    Tournassat, Christophe; Gaucher, Eric C.; Leupin, Olivier X.; Wersin, Paul

    2010-01-01

    Document available in extended abstract form only. An in-situ test in the Opalinus Clay formation, termed pore water Chemistry (PC) experiment, was run for a period of five years. It was based on the concept of diffusive equilibration whereby traced water with a composition close to that expected in the formation was continuously circulated and monitored in a packed off borehole. The main original focus was to obtain reliable data on the pH/pCO 2 of the pore water, but because of unexpected microbially- induced redox reactions, the objective was then changed to elucidate the biogeochemical processes happening in the borehole and to understand their impact on pH/pCO 2 and pH in the low permeability clay formation. The biologically perturbed chemical evolution of the PC experiment was simulated with reactive transport models. The aim of this modelling exercise was to develop a 'minimal-' model able to reproduce the chemical evolution of the PC experiment, i.e. the chemical evolution of solute inorganic and organic compounds (organic carbon, dissolved inorganic carbon etc...) that are coupled with each other through the simultaneous occurrence of biological transformation of solute or solid compounds, in-diffusion and out-diffusion of solute species and precipitation/dissolution of minerals (in the borehole and in the formation). An accurate description of the initial chemical conditions in the surrounding formation together with simplified kinetics rule mimicking the different phases of bacterial activities allowed reproducing the evolution of all main measured parameters (e.g. pH, TOC). Analyses from the overcoring and these simulations evidence the high buffer capacity of Opalinus clay regarding chemical perturbations due to bacterial activity. This pH buffering capacity is mainly attributed to the carbonate system as well as to the clay surfaces reactivity. Glycerol leaching from the pH-electrode might be the primary organic source responsible for

  16. Biological stress reactivity as an index of the two polarities of the experience model.

    Science.gov (United States)

    Silva, Jaime R; Vivanco-Carlevari, Anastassia; Barrientos, Mauricio; Martínez, Claudio; Salazar, Luis A; Krause, Mariane

    2017-10-01

    The two-polarities model of personality argues that experience is organized around two axes: interpersonal relatedness and self-definition. Differential emphasis on one of these poles defines adaptive and pathological experiences, generating anaclitic or introjective tendencies. The anaclitic pattern, on one hand, has been conceptually related with an exaggerated emphasis on interpersonal relatedness. On the other hand, the introjective pattern has been connected to high levels of self-criticism. The aim of this study was to investigate the psychophysiological basis for this relationship. Specifically, we hypothesized that the anaclitic individual should have a higher biological reactivity to stress (BRS), measured by the cortisol concentration in saliva, in an interpersonal stress induction protocol (Trier Social Stress Test). Contrary to what was expected, the results indicated that introjective participants presented a higher BSR than the anaclitic group. Interestingly, in contrast to their higher BSR, the introjective group reported a diminished subjective stress in relation to the average. In the anaclitic group, a tendency that goes in the opposite direction was found. Theoretical implications of these findings were discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Energy performance of a micro-cogeneration device during transient and steady-state operation: Experiments and simulations

    International Nuclear Information System (INIS)

    Rosato, Antonio; Sibilio, Sergio

    2013-01-01

    Micro-cogeneration is a well-established technology and its deployment has been considered by the European Community as one of the most effective measure to save primary energy and to reduce greenhouse gas emissions. As a consequence, the estimation of the potential impact of micro-cogeneration devices is necessary to design policy and to energetically, ecologically and economically rank these systems among other potential energy saving and CO 2 -reducing measures. Even if transient behaviour can be very important when the engine is frequently started and stopped and allowed to cool-down in between, for the sake of simplicity mainly static and simplified methods are used for assessing the performance of cogeneration devices, completely neglecting the dynamic response of the units themselves. In the first part of this paper a series of experiments is illustrated and discussed in detail in order to highlight and compare the transient and stationary operation of a natural gas fuelled reciprocating internal combustion engine based cogeneration unit with 6.0 kW as nominal electric output and 11.7 kW as nominal thermal output. The measured performance of the cogeneration device is also compared with the performance of the system calculated on the basis of the efficiency values suggested by the manufacturer in order to highlight and quantify the discrepancy between the two approaches in evaluating the unit operation. Finally the experimental data are also compared with those predicted by a simulation model developed within IEA/ECBCS Annex 42 and experimentally calibrated by the authors in order to assess the model reliability for studying and predicting the performance of the system under different operating scenarios. -- Highlights: ► Transient operation of a cogeneration system has been experimentally investigated. ► Steady-state operation of a cogeneration device has been experimentally evaluated. ► Measured data have been compared with those predicted by a

  18. Suppression of Transient Events by Levitation (STABLE): Results From the USML-2 Mission. Experiment 38

    Science.gov (United States)

    Nurre, Gerald S.; Edberg, Donald L.

    1998-01-01

    Microgravity science payloads can be extremely sensitive to vibrations from machinery, acoustics, ventilation, and crew activity. Suppression of Transient Acceleration by Levitation (STABLE) is an active vibration isolation system designed to protect payloads from these disturbances. This paper gives an account of results from the flight demonstration of the STABLE microgravity isolation system, which was developed and successfully flight tested in orbit during USML-2, with the participation of Astronaut Fred Leslie. Following a very brief description of the operational principles, the hardware and software design, and performance criteria, results of the analysis of measured flight data are presented to provide an evaluation of system performance parameters, including acceleration attenuation, assessment of sway space, system power consumption, and other factors critical to the performance of an isolation system. Lessons learned and potential design improvements and evolutions are discussed. Data reduction by Robert Boucher of McDonnell Douglas Aerospace (MDA) was substantially assisted by Kenneth Hrovat of Tal-Cut, Inc., under support from National Aeronautics and Space Administration/Lewis Research Center (LeRC), Cleveland, OH.

  19. Lifetimes and reactivities of some 1,2-didehydroazepines commonly used in photoaffinity labeling experiments in aqueous solutions.

    Science.gov (United States)

    Rizk, Mary S; Shi, Xiaofeng; Platz, Matthew S

    2006-01-17

    The reactive 1,2-didehydroazepine (cyclic ketenimine) intermediates produced upon photolysis of phenyl azide, 3-hydroxyphenyl azide, 3-methoxyphenyl azide, and 3-nitrophenyl azide in water and in HEPES buffer were studied by laser flash photolysis techniques with UV-vis detection of the transient intermediates. The lifetimes of the 1,2-didehydroazepines were obtained along with the absolute rate constants of their reactions with typical amino acids, nucleosides, and other simple reagents present in a biochemical milieu. The nitro substituent greatly accelerates the bimolecular reactions of the cyclic ketenimines, and the 3-methoxy group greatly decelerates the absolute reactivity of 1,2-didehydroazepines. The intermediate produced by photolysis of 3-hydroxyphenyl azide is much more reactive than the intermediate produced by photolysis of 3-methoxyphenyl azide. We propose that the hydroxyl-substituted 1,2-didehydoazepines rapidly (ketenimines undergo hydrolysis. Azepinones react more rapidly with nucleophiles than do methoxy-substituted 1,2-didehydroazepines and are the active species present upon the photolysis of 3-hydroxyphenyl azide in aqueous solution.

  20. Mild neonatal hyperthyrotrophinaemia: 10-year experience suggests the condition is increasingly common but often transient.

    Science.gov (United States)

    Oren, Asaf; Wang, Michael K; Brnjac, Lori; Mahmud, Farid H; Palmert, Mark R

    2013-12-01

    To examine a large population of infants with mild neonatal hyperthyrotrophinaemia (MNH) and determine prevalence, clinical characteristics and treatment history. Retrospective study of infants with MNH followed at The Hospital for Sick Children between 2000 and 2011. MNH was defined by an abnormal newborn screen followed by thyroid-stimulating hormone (TSH) between 5 and 30 mU/l and normal free T4 (FT4) on confirmatory tests. Mild neonatal hyperthyrotrophinaemia represented 22·3% of patients (103/462; 60 boys, 43 girls) within our clinic. Incidence increased from two of 20 in 2000 to 31 of 74 cases in 2010. Seventy eight percent of patients started L-thyroxine (initial dose: 8·3 ± 2·5 mcg/kg). The treated group had higher confirmatory TSH levels (P = 0·001) and had undergone thyroid scintigraphy more often (P = 0·0001) compared with the nontreated group. Evidence of overtreatment was detected in 45% of thyroid function tests obtained during treatment. Among the treated infants who had reached 3 years of age, 45% (N = 14) underwent a trial-off medication. Compared with those not trialled-off therapy, these infants were less likely to have had dose escalations during treatment (P = 0·001). The trial-off treatment was successful in 50% of cases. In the subset of infants with confirmatory TSH >10 mU/l, trial-off therapy was successful in 40%. None of the assessed variables predicted success of trial-off therapy. Mild neonatal hyperthyrotrophinaemia is an increasingly common diagnosis. It is more common in males and is often transient, but predictors of success of trial-off therapy were not identified. Further studies are needed to determine optimum L-thyroxine dosing and to determine whether treatment improves neurocognitive outcomes. © 2013 John Wiley & Sons Ltd.

  1. Experimental demonstration of tokamak inductive flux saving by transient coaxial helicity injection on national spherical torus experiment

    Energy Technology Data Exchange (ETDEWEB)

    Raman, R.; Jarboe, T. R.; Nelson, B. A. [University of Washington, Seattle, Washington 98195 (United States); Mueller, D.; Bell, M. G.; Gerhardt, S.; LeBlanc, B.; Menard, J.; Ono, M.; Roquemore, L. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Soukhanovskii, V. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2011-09-15

    Discharges initiated by transient coaxial helicity injection in National Spherical Torus Experiment have attained peak toroidal plasma currents up to 300 kA. When induction from the central solenoid is then applied, these discharges develop up to 300 kA additional current compared to discharges initiated by induction only. CHI initiated discharges in NSTX have achieved 1 MA of plasma current using only 258 mWb of solenoid flux whereas standard induction-only discharges require about 50% more solenoid flux to reach 1 MA. In addition, the CHI-initiated discharge has lower plasma density and a low normalized internal plasma inductance of 0.35, as needed for achieving advanced scenarios in NSTX.

  2. Determination of transport and reaction swarm coefficients from the analysis of complex transient pulses from the pulsed Townsend experiment

    International Nuclear Information System (INIS)

    Bekstein, A; De Urquijo, J; Rodríguez-Luna, J C; Juárez, A M; Ducasse, O

    2012-01-01

    We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.

  3. Transforming the Organic Chemistry Lab Experience: Design, Implementation, and Evaluation of Reformed Experimental Activities--REActivities

    Science.gov (United States)

    Collison, Christina G.; Kim, Thomas; Cody, Jeremy; Anderson, Jason; Edelbach, Brian; Marmor, William; Kipsang, Rodgers; Ayotte, Charles; Saviola, Daniel; Niziol, Justin

    2018-01-01

    Reformed experimental activities (REActivities) are an innovative approach to the delivery of the traditional material in an undergraduate organic chemistry laboratory. A description of the design and implementation of REActivities at both a four- and two-year institution is discussed. The results obtained using a reformed teaching observational…

  4. Factors influencing reliability of liver stiffness measurements using transient elastography (M-probe)—Monocentric experience

    Energy Technology Data Exchange (ETDEWEB)

    Şirli, Roxana, E-mail: roxanasirli@gmail.com; Sporea, Ioan, E-mail: isporea@umft.ro; Bota, Simona, E-mail: bota_simona1982@yahoo.com; Jurchiş, Ana, E-mail: ana.jurchis@yahoo.com

    2013-08-15

    Aim: To retrospectively assess the feasibility of transient elastography (TE) and the factors associated with failed and unreliable liver stiffness measurements (LSMs), in patients with chronic liver diseases. Material and methods: Our retrospective study included 8218 consecutive adult patients with suspected chronic liver diseases. In each patient, LSMs were performed with a FibroScan{sup ®} device (Echosens, France), with the M probe. Failure of TE measurements was defined if no valid measurement was obtained after at least 10 shots and unreliable if fewer than 10 valid shots were obtained, success rate (SR) <60% and/or interquartile range interval/median value (IQR/Med) ≥30%. Results: From the 8218 patients, failed and unreliable LSMs were observed in 29.2% of cases. In univariant analysis, the following risk factors were associated with failed and unreliable measurements: age over 50 years (OR 2.04; 95%CI 1.84–2.26), female gender (OR 1.32; 95%CI 1.20–1.45), BMI > 27.7 kg/m{sup 2} (OR 2.89, 95%CI 2.62–3.19), weight > 77 kg (OR 2.17; 95%CI 1.97–2.40) and height < 162 cm (OR 1.26; 95%CI 1.14–1.40). In multivariate analysis all the factors mentioned above were independently associated with the risk of failed and unreliable measurements. If all the negative predictive factors were present (woman, older than 50 years, with BMI > 27.7 kg/m{sup 2}, heavier than 77 kg and shorter than 162 cm), the rate of failed and unreliable measurements was 58.5%. In obese patients (BMI ≥ 30 kg/m{sup 2}), the rate of failed and unreliable measurements was 49.5%. Conclusion: Failed and unreliable LSMs were observed in 29.1% of patients. Female gender, older age, higher BMI, higher weight and smaller height were significantly associated with failed and unreliable LSMs.

  5. Experiment for transient effects of sudden catastrophic loss of vacuum on a scaled superconducting radio frequency cryomodule

    International Nuclear Information System (INIS)

    Dalesandro, A.; Theilacker, J.; Van Sciver, S.W.

    2011-01-01

    Safe operation of superconducting radio frequency (SRF) cavities require design consideration of a sudden catastrophic loss of vacuum (SCLV) adjacent with liquid helium (LHe) vessels and subsequent dangers. An experiment is discussed to test the longitudinal effects of SCLV along the beam line of a string of scaled SRF cavities. Each scaled cavity includes one segment of beam tube within a LHe vessel containing 2 K saturated LHe, and a riser pipe connecting the LHe vessel to a common gas header. At the beam tube inlet is a fast acting solenoid valve to simulate SCLV and a high/low range orifice plate flow-meter to measure air influx to the cavity. The gas header exit also has an orifice plate flow-meter to measure helium venting the system at the relief pressure of 0.4 MPa. Each cavity is instrumented with Validyne pressure transducers and Cernox thermometers. The purpose of this experiment is to quantify the time required to spoil the beam vacuum and the effects of transient heat and mass transfer on the helium system. Heat transfer data is expected to reveal a longitudinal effect due to the geometry of the experiment. Details of the experimental design criteria and objectives are presented.

  6. On transient electric fields observed in chemical release experiments by rockets

    International Nuclear Information System (INIS)

    Marklund, G.; Brenning, N.; Holmgren, G.; Haerendel, G.

    1986-06-01

    As a follow-up to the successful chemical release experiment Trigger in 1977, the TOR (Trigger Optimized Repetition) rocket was launched from Esrange on Oct. 24, 1984. Like in the Trigger experiment a large amplitude electric field pulse of 200 mV/m was detected shortly after the explosion. The central part of the pulse was found to be clearly correlated with an intense layer of swept up ambient particles behind a propagating shock-front. The field was directed towards the centre of the expanding ionized cloud, which is indicative of a polarisation electric field source. Expressions for this radial polarisation field and the much weaker azimuthal induced electric field are derived from a simple cylindrical model for the field and the expanding neutral cloud. Time profiles of the radial electric field are shown to be in good agreement with observations. (authors)

  7. The experience of HIV reactive patients in rural Malawi - Part I

    Directory of Open Access Journals (Sweden)

    Y Sliep

    2001-09-01

    Full Text Available Malawi has a population of 9 million people with AIDS the leading cause of death in the 20 - 40 age group. The HIV positive prevalence rate, estimated at 23% in urban areas and 8% in rural areas, is one of the highest in the world (AIDSEC, 1994:1. Evaluation of counselling practices showed poor results with counsellors feeling ineffective and inadequate. Patients are mostly tested on medical indication but patients who do not see the benefit of knowing their HIV status increasingly refuse testing. The counselling practise as it is known in the Western world is a foreign concept for patients living in rural Malawi. The high stigma of AIDS complicates support of the patients. The goal of the research study was to describe a model of counselling that would meet the needs of an AIDS patient in rural community in Malawi. A qualitative research design that was explorative, descriptive and contextually specific to rural Malawi was used for the study. In order to describe a counselling model it was important to understand the illness experience of HIV reactive patients. The patients are seen in group context congruent with the African culture and therefore the experience of the primary care giver of AIDS patients is explored as the other major factor in the phenomenon examined. One phase of the research is described in this article namely exploring and describing the experience of the HIV reactive patient in rural Malawi. Results show that patients are in an advanced stage of AIDS when they are diagnosed and complain of weakness and an inability to do work, including an inability to do their daily chores. This causes a feeling of desperateness that is worsened by the perception that support systems are inadequate. Support systems are mostly identified as parents, partners and siblings to assist mainly with the physical care and financial support. Despite the fact that the family is very important to patients there is a reluctance to acknowledge their

  8. Transient Atmospheric Circulation Changes in a Grand ensemble of Idealized CO2 Increase Experiments

    Science.gov (United States)

    Karpechko, A.; Manzini, E.; Kornblueh, L.

    2017-12-01

    The yearly evolution with increasing forcing of the large-scale atmospheric circulation is examined in a 68-member ensemble of 1pctCO2 scenario experiments performed with the MPI-ESM model. Each member of the experiment ensemble is integrated for 155 years, from initial conditions taken from a 2000-yr long pre-industrial control climate experiment. The 1pctCO2 scenario experiments are conducted following the protocol of including as external forcing only a CO2 concentration increase at 1%/year, till quadrupling of CO2 concentrations. MPI-ESM is the Max-Planck-Institute Earth System Model (including coupling between the atmosphere, ocean and seaice). By averaging over the 68 members (ensemble mean), atmospheric variability is greatly reduced. Thus, it is possible to investigate the sensitivity to the climate state of the atmospheric response to CO2 doubling. Indicators of global change show the expected monotonic evolution with increasing CO2 and a weak dependence of the thermodynamical response to CO2 doubling on the climate state. The surface climate response of the atmospheric circulation, diagnosed for instance by the pressure at sea level, and the eddy-driven jet response show instead a marked dependence to the climate state, for the Northern winter season. We find that as the CO2 concentration increases above doubling, Northern winter trends in some indicators of atmospheric circulation changes decrease or even reverse, posing the question on what are the causes of this nonlinear behavior. The investigation of the role of stationary waves, the meridional overturning circulation, the decrease in Arctic sea ice and the stratospheric vortex points to the latter as a plausible cause of such nonlinear response.

  9. Study on the reactive transient α-λ3-iodanyl-acetophenone complex in the iodine(III)/PhI(I) catalytic cycle of iodobenzene-catalyzed α-acetoxylation reaction of acetophenone by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Wang, Hao-Yang; Zhou, Juan; Guo, Yin-Long

    2012-03-30

    Hypervalent iodine compounds are important and widely used oxidants in organic chemistry. In 2005, Ochiai reported the PhI-catalyzed α-acetoxylation reaction of acetophenone by the oxidation of PhI with m-chloroperbenzoic acid (m-CPBA) in acetic acid. However, until now, the most critical reactive α-λ(3)-iodine alkyl acetophenone intermediate (3) had not been isolated or directly detected. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to intercept and characterize the transient reactive α-λ(3)-iodine alkyl acetophenone intermediate in the reaction solution. The trivalent iodine species was detected when PhI and m-CPBA in acetic acid were mixed, which indicated the facile oxidation of a catalytic amount of PhI(I) to the iodine(III) species by m-CPBA. Most importantly, 3·H(+) was observed at m/z 383 from the reaction solution and this ion gave the protonated α-acetoxylation product 4·H(+) at m/z 179 in MS/MS by an intramolecular reductive elimination of PhI. These ESI-MS/MS studies showed the existence of the reactive α-λ(3)-iodine alkyl acetophenone intermediate 3 in the catalytic cycle. Moreover, the gas-phase reactivity of 3·H(+) was consistent with the proposed solution-phase reactivity of the α-λ(3)-iodine alkyl acetophenone intermediate 3, thus confirming the reaction mechanism proposed by Ochiai. Copyright © 2012 John Wiley & Sons, Ltd.

  10. Impact of Adverse Childhood Experiences on Psychotic-Like Symptoms and Stress Reactivity in Daily Life in Nonclinical Young Adults.

    Directory of Open Access Journals (Sweden)

    Paula Cristóbal-Narváez

    Full Text Available There is increasing interest in elucidating the association of different childhood adversities with psychosis-spectrum symptoms as well as the mechanistic processes involved. This study used experience sampling methodology to examine (i associations of a range of childhood adversities with psychosis symptom domains in daily life; (ii whether associations of abuse and neglect with symptoms are consistent across self-report and interview methods of trauma assessment; and (iii the role of different adversities in moderating affective, psychotic-like, and paranoid reactivity to situational and social stressors.A total of 206 nonclinical young adults were administered self-report and interview measures to assess childhood abuse, neglect, bullying, losses, and general traumatic events. Participants received personal digital assistants that signaled them randomly eight times daily for one week to complete questionnaires about current experiences, including symptoms, affect, and stress.Self-reported and interview-based abuse and neglect were associated with psychotic-like and paranoid symptoms, whereas only self-reported neglect was associated with negative-like symptoms. Bullying was associated with psychotic-like symptoms. Losses and general traumatic events were not directly associated with any of the symptom domains. All the childhood adversities were associated with stress reactivity in daily life. Interpersonal adversities (abuse, neglect, bullying, and losses moderated psychotic-like and/or paranoid reactivity to situational and social stressors, whereas general traumatic events moderated psychotic-like reactivity to situational stress. Also, different interpersonal adversities exacerbated psychotic-like and/or paranoid symptoms in response to distinct social stressors.The present study provides a unique examination of how childhood adversities impact the expression of spectrum symptoms in the real world and lends support to the notion that

  11. Reactivity loss validation of high burn-up PWR fuels with pile-oscillation experiments in MINERVE

    Energy Technology Data Exchange (ETDEWEB)

    Leconte, P.; Vaglio-Gaudard, C.; Eschbach, R.; Di-Salvo, J.; Antony, M.; Pepino, A. [CEA, DEN, DER, Cadarache, F-13108 Saint-Paul-Lez-Durance (France)

    2012-07-01

    The ALIX experimental program relies on the experimental validation of the spent fuel inventory, by chemical analysis of samples irradiated in a PWR between 5 and 7 cycles, and also on the experimental validation of the spent fuel reactivity loss with bum-up, obtained by pile-oscillation measurements in the MINERVE reactor. These latter experiments provide an overall validation of both the fuel inventory and of the nuclear data responsible for the reactivity loss. This program offers also unique experimental data for fuels with a burn-up reaching 85 GWd/t, as spent fuels in French PWRs never exceeds 70 GWd/t up to now. The analysis of these experiments is done in two steps with the APOLLO2/SHEM-MOC/CEA2005v4 package. In the first one, the fuel inventory of each sample is obtained by assembly calculations. The calculation route consists in the self-shielding of cross sections on the 281 energy group SHEM mesh, followed by the flux calculation by the Method Of Characteristics in a 2D-exact heterogeneous geometry of the assembly, and finally a depletion calculation by an iterative resolution of the Bateman equations. In the second step, the fuel inventory is used in the analysis of pile-oscillation experiments in which the reactivity of the ALIX spent fuel samples is compared to the reactivity of fresh fuel samples. The comparison between Experiment and Calculation shows satisfactory results with the JEFF3.1.1 library which predicts the reactivity loss within 2% for burn-up of {approx}75 GWd/t and within 4% for burn-up of {approx}85 GWd/t. (authors)

  12. Equilibrium and transient conductivity for gadolinium-doped ceria under large perturbations: I. Experiments

    DEFF Research Database (Denmark)

    Ricote, Sandrine; Zhu, Huayang; Coors, W. Grover

    2014-01-01

    (97% O2, 3% H2O) and vice versa reveal great asymmetries in relaxation times. Virtually instantaneous relaxations are observed in the first case, while the oxidizing-to-reducing relaxations take as long as 0.5h. This paper reports conductivity relaxations with over 20 orders of magnitude in the gas......-phase oxygen partial pressure. Models and experiments are used to show that the observed asymmetries cannot be explained by electrode defects or two-dimensional end effects. The companion paper develops a Nernst–Planck–Poisson model to assist the quantitative interpretation of the measurements reported...

  13. Summary of transient high-voltage calculations for the FRX-C experiment

    International Nuclear Information System (INIS)

    Kewish, R.W. Jr.; Rej, D.J.

    1982-06-01

    Calculations of the electrical circuit equations are performed over a wide range of parameters corresponding to the FRX-C field-reversed THETA-pinch experiment at Los Alamos. Without any plasma or external damping, serious voltage doubling and quadrupling of the main capacitor bank charge voltage are observed. These oscillating high voltages are found to be adequately suppressed by the strategic placement of external snubber circuitry. On the other hand, no doubling of the THETA-pinch preionization bank charge voltage is found. Calculations of the equations for the z-pinch preionization circuit are also performed

  14. Analysis of metal fuel transient overpower experiments with the SAS4A accident analysis code

    International Nuclear Information System (INIS)

    Tentner, A.M.; Kalimullah; Miles, K.J.

    1990-01-01

    The results of the SAS4A analysis of the M7 TREAT Metal fuel experiment are presented. New models incorporated in the metal fuel version of SAS4A are described. The computational results are compared with the experimental observations and this comparison is used in the interpretation of physical phenomena. This analysis was performed using the integrated metal fuel SAS4A version and covers a wide range of events, providing an increased degree of confidence in the SAS4A metal fuel accident analysis capabilities

  15. Cerebrovascular endothelin-1 hyper-reactivity is associated with transient receptor potential canonical channels 1 and 6 activation and delayed cerebral hypoperfusion after forebrain ischaemia in rats

    DEFF Research Database (Denmark)

    Johansson, S E; Andersen, X E D R; Hansen, R H

    2015-01-01

    . METHODS: Experimental forebrain ischaemia was induced in Wistar male rats by a two-vessel occlusion model, and the cerebral blood flow was measured by magnetic resonance imaging two days after reperfusion. In vitro vasoreactivity studies, immunofluorescence and quantitative PCR were performed on cerebral...... in the vascular smooth muscle cells was enhanced and correlated with decreased cerebral blood flow two days after forebrain ischaemia. Furthermore, under conditions when voltage-dependent calcium channels were inhibited, endothelin-1-induced cerebrovascular contraction was enhanced and this enhancement...... was presumably mediated by Ca(2+) influx via upregulated transient receptor potential canonical channels 1 and 6. CONCLUSIONS: Our data demonstrates that endothelin-1-mediated influx of extracellular Ca(2+) activates transient receptor potential canonical channels 1 and 6 in cerebral vascular smooth muscle cells...

  16. Photogeneration of reactive transient species upon irradiation of natural water samples: Formation quantum yields in different spectral intervals, and implications for the photochemistry of surface waters.

    Science.gov (United States)

    Marchisio, Andrea; Minella, Marco; Maurino, Valter; Minero, Claudio; Vione, Davide

    2015-04-15

    Chromophoric dissolved organic matter (CDOM) in surface waters is a photochemical source of several transient species such as CDOM triplet states ((3)CDOM*), singlet oxygen ((1)O2) and the hydroxyl radical (OH). By irradiation of lake water samples, it is shown here that the quantum yields for the formation of these transients by CDOM vary depending on the irradiation wavelength range, in the order UVB > UVA > blue. A possible explanation is that radiation at longer wavelengths is preferentially absorbed by the larger CDOM fractions, which show lesser photoactivity compared to smaller CDOM moieties. The quantum yield variations in different spectral ranges were definitely more marked for (3)CDOM* and OH compared to (1)O2. The decrease of the quantum yields with increasing wavelength has important implications for the photochemistry of surface waters, because long-wavelength radiation penetrates deeper in water columns compared to short-wavelength radiation. The average steady-state concentrations of the transients ((3)CDOM*, (1)O2 and OH) were modelled in water columns of different depths, based on the experimentally determined wavelength trends of the formation quantum yields. Important differences were found between such modelling results and those obtained in a wavelength-independent quantum yield scenario. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Generation of pyroclastic density currents from pyroclastic fountaining or transient explosions: insights from large scale experiments

    Energy Technology Data Exchange (ETDEWEB)

    Sulpizio, Roberto; Dellino, Pierfrancesco; Mele, Daniela; La Volpe, Luigi [CIRISIVU, c/o Dipartimento Geomineralogico, via Orabona 4, 70125, Bari (Italy)], E-mail: r.sulpizio@geomin.uniba.it

    2008-10-01

    Pyroclastic density currents (PDCs) are among the most amazing, complex and dangerous volcanic phenomena. They are moving mixtures of particles and gas that flow across the ground, and originate in different ways and from various sources, during explosive eruptions or gravity-driven collapse of domes. We present results from experimental work to investigate the generation of large-scale, multiphase, gravity-driven currents. The experiments described here are particularly devoted to understanding the inception and development of PDCs under impulsive injection conditions by means of the fast application of a finite stress to a finite mass of pyroclastic particles via expansion of compressed gas. We find that, in summary, PDC generation from collapse of pressure-adjusted or overpressurised pyroclastic jets critically depends on behaviour of injection into the atmosphere, which controls the collapsing mechanisms and then the physical parameters of the initiating current.

  18. Operation databook of the fuel treatment system of the Static Experiment Critical Facility (STACY) and the Transient Experiment Critical Facility (TRACY). JFY 2004 to JFY 2008

    International Nuclear Information System (INIS)

    Kokusen, Junya; Sumiya, Masato; Seki, Masakazu; Kobayashi, Fuyumi; Ishii, Junichi; Umeda, Miki

    2013-02-01

    Uranyl nitrate solution fuel used in the Static Experiment Critical Facility (STACY) and the Transient Experiment Critical Facility (TRACY) is adjusted in the Fuel Treatment System, in which such parameters are varied as concentration of uranium, free nitric acid, soluble neutron poison, and so on. Operations for concentration and denitration of the solution fuel were carried out with an evaporator from JFY 2004 to JFY 2008 in order to adjust the fuel to the experimental condition of the STACY and the TRACY. In parallel, the solution fuel in which some kinds of soluble neutron poison were doped was also adjusted in JFY 2005 and JFY 2006 for the purpose of the STACY experiments to determine neutron absorption effects brought by fission products, etc. After these experiments in the STACY, a part of the solution fuel including the soluble neutron poison was purified by the solvent extraction method with mixer-settlers in JFY 2006 and JFY 2007. This report summarizes operation data of the Fuel Treatment System from JFY 2004 to JFY 2008. (author)

  19. Thermophysical Property Estimation by Transient Experiments: The Effect of a Biased Initial Temperature Distribution

    Directory of Open Access Journals (Sweden)

    Federico Scarpa

    2015-01-01

    Full Text Available The identification of thermophysical properties of materials in dynamic experiments can be conveniently performed by the inverse solution of the associated heat conduction problem (IHCP. The inverse technique demands the knowledge of the initial temperature distribution within the material. As only a limited number of temperature sensors (or no sensor at all are arranged inside the test specimen, the knowledge of the initial temperature distribution is affected by some uncertainty. This uncertainty, together with other possible sources of bias in the experimental procedure, will propagate in the estimation process and the accuracy of the reconstructed thermophysical property values could deteriorate. In this work the effect on the estimated thermophysical properties due to errors in the initial temperature distribution is investigated along with a practical method to quantify this effect. Furthermore, a technique for compensating this kind of bias is proposed. The method consists in including the initial temperature distribution among the unknown functions to be estimated. In this way the effect of the initial bias is removed and the accuracy of the identified thermophysical property values is highly improved.

  20. [VDRL and FTA-ABS reactivity in cerebrospinal fluid: our experience].

    Science.gov (United States)

    García-Rodríguez, J A; Martín-Sánchez, A M; Canut, A; García-García, L; Cacho, J

    1990-01-01

    The reactivity of 194 samples of CSF against VDRL and FTA-ABS was studied in patients attending the Clinical Hospital in Salamanca over a five years period. This laboratory was asked to rule out an etiology of syphilis. Twelve samples of CSF proved to be reactive (6.2%) against VDRL and/or FTA-ABS. Seven of these corresponded to six adults diagnosed as suffering from neurosyphilis and one to an infant with early congenital syphilis without neurological alterations; these had in common the presence of active syphilis and a reactive FTA-ABS in serum. In the CSF of the six cases of neurosyphilis, VDRL was reactive in two patients (33.3%) and FTA-ABS in five (83.3%). One minimally reactive VDRL and four FTA-ABS were detected in the remaining five patients, with no known previous history of syphilis, that were suffering from different neurological alterations and that had a nonreactive FTA-ABS in serum. The results obtained in this study point to inappropriate use in CSF of VDRL and FTA-ABS to exclude neurosyphilis in our hospital since only 3.6% of the CSF studied corresponded to patients diagnosed as suffering from neurosyphilis and also to the need for improving the criteria for patient selection.

  1. Acetylene and carbon monoxide oxidation over a Pt/Rh/CeO2/γ-Al2O3 automotive exhaust gas catalyst: kinetic modelling of transient experiments

    NARCIS (Netherlands)

    Harmsen, J.M.A.; Hoebink, J.H.B.J.; Schouten, J.C.

    2001-01-01

    The transient kinetics of acetylene (C2H2) conversion by oxygen over a commercial Pt/Rh/CeO2/¿-Al2O3 three-way catalyst have been modelled. Experiments to validate the model were carried out in a fixed-bed reactor with two separate inlets, enabling alternate feeding of acetylene and oxygen.

  2. Potential impact of reactive vaccination in controlling cholera outbreaks: an exploratory analysis using a Zimbabwean experience.

    Science.gov (United States)

    Kim, Sun-Young; Choi, Yeongchull; Mason, Peter R; Rusakaniko, Simbarashe; Goldie, Sue J

    2011-09-05

    To contain ongoing cholera outbreaks, the World Health Organization has suggested that reactive vaccination should be considered in addition to its previous control measures. To explore the potential impact of a hypothetical reactive oral cholera vaccination using the example of the recent large-scale cholera outbreak in Zimbabwe. This was a retrospective cost-effectiveness analysis calculating the health and economic burden of the cholera outbreak in Zimbabwe with and without reactive vaccination. The primary outcome measure was incremental cost per disability-adjusted life year (DALY) averted. Under the base-case assumptions (assuming 50% coverage among individuals aged ≥2 years), reactive vaccination could have averted 1 320 deaths and 23 650 DALYs. Considering herd immunity, the corresponding values would have been 2 920 deaths and 52 360 DALYs averted. The total vaccination costs would have been ~$74 million and ~$21 million, respectively, with per-dose vaccine price of US$5 and $1. The incremental costs per DALY averted of reactive vaccination were $2 770 and $370, respectively, for vaccine price set at $5 and $1. Assuming herd immunity, the corresponding cost was $980 with vaccine price of $5, and the programme was cost-saving with a vaccine price of $1. Results were most sensitive to case-fatality rate, per-dose vaccine price, and the size of the outbreak. Reactive vaccination has the potential to be a cost-effective measure to contain cholera outbreaks in countries at high risk. However, the feasibility of implementation should be further evaluated, and caution is warranted in extrapolating the findings to different settings in the absence of other in-depth studies.

  3. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BURST AND TRANSIENT SOURCE EXPERIMENT 5B CATALOG OF COSMIC GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    Hurley, K.; Briggs, M. S.; Kippen, R. M.; Kouveliotou, C.; Fishman, G.; Meegan, C.; Cline, T.; Trombka, J.; McClanahan, T.; Boynton, W.; Starr, R.; McNutt, R.; Boer, M.

    2011-01-01

    We present Interplanetary Network localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or t riangulation ) results in an annulus of possible arrival directions whose half-width varies between 11 arcsec and 21 0 , depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48,000 arcmin 2 , resulting in an average reduction of the BATSE error circle area of a factor of 87.

  4. Summarizing evaluation of the results of in-pile experiments for the transient fission gas release under accidental conditions of fast breeders

    International Nuclear Information System (INIS)

    Fischer, E.A.; Vaeth, L.

    1989-04-01

    The transient fission gas behaviour and the fission gas induced fuel motion were studied in in-pile experiments in different countries, under conditions typical for hypothetical accidents. This report summarizes first the different experiment series and the main results. Then, a comparative evaluation is given, which provides a basis for the choice of the fission gas parameters in the accident code SAS3D

  5. A reactive transport investigation of a seawater intrusion experiment in a shallow aquifer, Skansehage Denmark

    DEFF Research Database (Denmark)

    Christensen, Flemming Damgaard; Engesgaard, Peter Knudegaard; Kipp, K.L.

    2001-01-01

    Previous investigations on seawater intrusion have mainly focused on either the physical density flow system with transport of a single non-reactive species or focused on the geochemical aspects neglecting density effects. This study focuses on both the geochemical and physical aspects of seawate...

  6. Reactivity worth measurements on fast burst reactor Caliban - description and interpretation of integral experiments for the validation of nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Richard, B. [Commissariat a l' Energie Atomique et Aux Energies Alternatives CEA, DAM, VALDUC, F-21120 Is-sur-Tille (France)

    2012-07-01

    Reactivity perturbation experiments using various materials are being performed on the HEU fast core CALIBAN, an experimental device operated by the CEA VALDUC Criticality and Neutron Transport Research Laboratory. These experiments provide valuable information to contribute to the validation of nuclear data for the materials used in such measurements. This paper presents the results obtained in a first series of measurements performed with Au-197 samples. Experiments which have been conducted in order to improve the characterization of the core are also described and discussed. The experimental results have been compared to numerical calculation using both deterministic and Monte Carlo neutron transport codes with a simplified model of the reactor. This early work led to a methodology which will be applied to the future experiments which will concern other materials of interest. (authors)

  7. EXPERIENCE OF DESOXIRIBONUCLEATE SODIUM IMMUNOMODULATOR APPLICATION IN TREATMENT FOR REACTIVE ARTHRITIS OF CHLAMYDIA AETIOLOGY AMONG CHILDREN

    Directory of Open Access Journals (Sweden)

    L.A. Balykova

    2007-01-01

    Full Text Available Researchers compared efficacy of the conventional therapy (oilment with non steriod anti-inflammatory medication, diclofena sodium and azithromycin among children with reactive arthritis of Chlamydia etiology and treatment with introduction of gluccosaminilmuramildi peptide and desoxiribonucleate sodium immunomodulators. The article shows that application of immunomodulators in combination with the conventional therapy provided for the decrease of the articular syndrome intensity, reduced the need of the patients in local corticosteroids and conduced to the reduction of the lab process activity indices. Further more, they noticed reduced recurrence of the antibodies to Chlamydias and their titers in the blood serum, while general intensity of the antiinflammatory effects from the combined therapy, which included glucosaminilmuramildipeptide and desoxiribonucleate sodium immunomodulators along with the antibiotic, proved to be comparable.Key words: children, reactive arthritis, chlamydia infection, immunomodulators.

  8. Attenuation of pyrite oxidation with a fly ash pre-barrier: Reactive transport modelling of column experiments

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, R.; Cama, J.; Nieto, J.M.; Ayora, C.; Saaltink, M.W. [University of Huelva, Huelva (Spain). Dept. of Geology

    2009-09-15

    Conventional permeable reactive barriers (PRBs) for passive treatment of groundwater contaminated by acid mine drainage (AMD) use limestone as reactive material that neutralizes water acidity. However, the limestone-alkalinity potential ceases as inevitable precipitation of secondary metal-phases on grain surfaces occurs, limiting its efficiency. In the present study, fly ash derived from coal combustion is investigated as an alternative alkalinity generating material for the passive treatment of AMD using solution-saturated column experiments. Unlike conventional systems, the utilization of fly ash in a pre-barrier to intercept the non-polluted recharge water before this water reacts with pyrite-rich wastes is proposed. Chemical variation in the columns was interpreted with the reactive transport code RETRASO. In parallel, kinetics of fly ash dissolution at alkaline pH were studied using flow-through experiments and incorporated into the model. In a saturated column filled solely with pyritic sludge-quartz sand (1: 10), oxidation took place at acidic conditions (pH 3.7). According to SO{sub 4}{sup 2-} release and pH, pyrite dissolution occurred favourably in the solution-saturated porous medium until dissolved O{sub 2} was totally consumed. In a second saturated column, pyrite oxidation took place at alkaline conditions (pH 10.45) as acidity was neutralized by fly ash dissolution in a previous level. At this pH Fe release from pyrite dissolution was immediately depleted as Fe-oxy(hydroxide) phases that precipitated on the pyrite grains, forming Fe-coatings (microencapsulation). With time, pyrite microencapsulation inhibited oxidation in practically 97% of the pyritic sludge. Rapid pyrite-surface passivation decreased its reactivity, preventing AMD production in the relatively short term.

  9. Reactivity to Social Stress in Subclinical Social Anxiety: Emotional Experience, Cognitive Appraisals, Behavior, and Physiology

    OpenAIRE

    Crişan, Liviu G.; Vulturar, Romana; Miclea, Mircea; Miu, Andrei C.

    2016-01-01

    Recent research indicates that subclinical social anxiety is associated with dysfunctions at multiple psychological and biological levels, in a manner that seems reminiscent of social anxiety disorder (SAD). This study aimed to describe multidimensional responses to laboratory-induced social stress in an analog sample selected for social anxiety symptoms. State anxiety, cognitive biases related to negative social evaluation, speech anxiety behaviors, and cortisol reactivity were assessed in t...

  10. Reactive case detection for malaria elimination: real-life experience from an ongoing program in Swaziland.

    Science.gov (United States)

    Sturrock, Hugh J W; Novotny, Joe M; Kunene, Simon; Dlamini, Sabelo; Zulu, Zulisile; Cohen, Justin M; Hsiang, Michelle S; Greenhouse, Bryan; Gosling, Roly D

    2013-01-01

    As countries move towards malaria elimination, methods to identify infections among populations who do not seek treatment are required. Reactive case detection, whereby individuals living in close proximity to passively detected cases are screened and treated, is one approach being used by a number of countries including Swaziland. An outstanding issue is establishing the epidemiologically and operationally optimal screening radius around each passively detected index case. Using data collected between December 2009 and June 2012 from reactive case detection (RACD) activities in Swaziland, we evaluated the effect of screening radius and other risk factors on the probability of detecting cases by reactive case detection. Using satellite imagery, we also evaluated the household coverage achieved during reactive case detection. Over the study period, 250 cases triggered RACD, which identified a further 74 cases, showing the value of RACD over passive surveillance alone. Results suggest that the odds of detecting a case within the household of the index case were significantly higher than in neighbouring households (odds ratio (OR) 13, 95% CI 3.1-54.4). Furthermore, cases were more likely to be detected when RACD was conducted within a week of the index presenting at a health facility (OR 8.7, 95% CI 1.1-66.4) and if the index household had not been sprayed with insecticide (OR sprayed vs not sprayed 0.11, 95% CI 0.03-0.46). The large number of households missed during RACD indicates that a 1 km screening radius may be impractical in such resource limited settings such as Swaziland. Future RACD in Swaziland could be made more effective by achieving high coverage amongst individuals located near to index cases and in areas where spraying has not been conducted. As well as allowing the programme to implement RACD more rapidly, this would help to more precisely define the optimal screening radius.

  11. Biogeochemical Reactive Transport Model of the Redox Zone Experiment of the sp Hard Rock Laboratory in Sweden

    International Nuclear Information System (INIS)

    Molinero-Huguet, Jorge; Samper-Calvete, F. Javier; Zhang, Guoxiang; Yang, Changbing

    2004-01-01

    Underground facilities are being operated by several countries around the world for performing research and demonstration of the safety of deep radioactive waste repositories. The ''sp'' Hard Rock Laboratory is one such facility launched and operated by the Swedish Nuclear Fuel and Waste Management Company where various in situ experiments have been performed in fractured granites. One such experiment is the redox zone experiment, which aimed at evaluating the effects of the construction of an access tunnel on the hydrochemical conditions of a fracture zone. Dilution of the initially saline groundwater by fresh recharge water is the dominant process controlling the hydrochemical evolution of most chemical species, except for bicarbonate and sulfate, which unexpectedly increase with time. We present a numerical model of water flow, reactive transport, and microbial processes for the redox zone experiment. This model provides a plausible quantitatively based explanation for the unexpected evolution of bicarbonate and sulfate, reproduces the breakthrough curves of other reactive species, and is consistent with previous hydrogeological and solute transport models

  12. Contributions of primary and secondary biogenic VOC tototal OH reactivity during the CABINEX (Community Atmosphere-Biosphere INteractions Experiments-09 field campaign

    Directory of Open Access Journals (Sweden)

    S. Kim

    2011-08-01

    Full Text Available We present OH reactivity measurements using the comparative reactivity method with a branch enclosure technique for four different tree species (red oak, white pine, beech and red maple in the UMBS PROPHET tower footprint during the Community Atmosphere Biosphere INteraction EXperiment (CABINEX field campaign in July of 2009. Proton Transfer Reaction-Mass Spectrometry (PTR-MS was sequentially used as a detector for OH reactivity and BVOC concentrations including isoprene and monoterpenes (MT for enclosure air. Therefore, the measurement dataset contains both measured and calculated OH reactivity from well-known BVOC. The results indicate that isoprene and MT, and in one case a sesquiterpene, can account for the measured OH reactivity. Significant discrepancy between measured OH reactivity and calculated OH reactivity from isoprene and MT is found for the red maple enclosure dataset but it can be reconciled by adding reactivity from emission of a sesquiterpene, α-farnesene, detected by GC-MS. This leads us to conclude that no significant unknown BVOC emission contributed to ambient OH reactivity from these trees at least during the study period. However, this conclusion should be followed up by more comprehensive side-by-side intercomparison between measured and calculated OH reactivity and laboratory experiments with controlled temperature and light environments to verify effects of those essential parameters towards unknown/unmeasured reactive BVOC emissions. This conclusion leads us to explore the contribution towards ambient OH reactivity (the dominant OH sink in this ecosystem oxidation products such as hydroxyacetone, glyoxal, methylglyoxal and C4 and C5-hydroxycarbonyl using recently published isoprene oxidation mechanisms (Mainz Isoprene Mechanism II and Leuven Isoprene Mechanism. Evaluation of conventionally unmeasured first generation oxidation products of isoprene and their possible contribution to ambient missing OH reactivity

  13. Determination of the design excess reactivity for the TREAT Upgrade reactor

    International Nuclear Information System (INIS)

    Bhattacharyya, S.K.; Hanan, N.A.

    1983-01-01

    The excess reactivity designed to be built into a reactor core is a primary determinant of the fissile loadings of the fuel rods in the core. For the TREAT Upgrade (TU) reactor the considerations that enter into the determination of the excess reactivity are different from those of conventional power reactors. The reactor is designed to operate in an adiabatic transient mode for reactor safety in-pile test programs. The primary constituent of the excess reactivity is the calculated reactivity required to perform the most demanding transient experiments. Because of the unavailability of supporting critical experiments for the core design, the uncertainty terms that add on to this basic constituent are rather large. The burnup effects in TU are negligible and no refueling is planned. In this paper the determination of the design excess reactivity of the TREAT Upgrade reactor is discussed

  14. FFTF fuel pin design procedure verification for transient operation

    International Nuclear Information System (INIS)

    Baars, R.E.

    1975-05-01

    The FFTF design procedures for evaluating fuel pin transient performance are briefly reviewed, and data where available are compared with design procedure predictions. Specifically, burst conditions derived from Fuel Cladding Transient Tester (FCTT) tests and from ANL loss-of-flow tests are compared with burst pressures computed using the design procedure upon which the cladding integrity limit was based. Failure times are predicted using the design procedure for evaluation of rapid reactivity insertion accidents, for five unterminated TREAT experiments in which well characterized fuel failures were deliberately incurred. (U.S.)

  15. French experience in transient data collection and fatigue monitoring of PWR`s nuclear steam supply system; Experience francaise sur la comptabilisation des transitoires et la surveillance en fatigue des chaudieres REP

    Energy Technology Data Exchange (ETDEWEB)

    Sabaton, M.; Morilhat, P.; Savoldelli, D.; Genette, P.

    1995-10-01

    Electricite de France (EDF), the french national electricity company, is operating 54 standardized pressurizer water reactors. This about 500 reactor-years experience in nuclear stations operation and maintenance area has allowed EDF to develop its own strategy for monitoring of age-related degradations of NPP systems and components relevant for plant safety and reliability. After more than fifteen years of experience in regulatory transient data collection and seven years of successful fatigue monitoring prototypes experimentation, EDF decided to design a new system called SYSFAC (acronym for SYsteme de Surveillance en FAtigue de la Chaudiere) devoted to transient logging and thermal fatigue monitoring of the reactor coolant pressure boundary. The system is fully automatic and directly connected to the on-site data acquisition network without any complementary instrumentation. A functional transient detection module and a mechanical transient detection module are in charge of the general transient data collection. A fatigue monitoring module is aimed towards a precise surveillance of five specific zones particularly sensible to thermal fatigue. After the first step of preliminary studies, the industrial phase of the SYSFAC project is currently going on, with hardware and software tests and implementation. The first SYSFAC system will be delivered to the pilot power plant by the beginning of 1996. The extension to all EDF`s nuclear 900 MW is planned after one more year of feedback experience. (authors). 12 refs., 3 figs.

  16. Power transients of Ghana research reactor-1 using PARET/ANL thermal hydraulic code

    International Nuclear Information System (INIS)

    Ampomah-Amoaka, E.; Akaho, E.H.K.; Anim-Sampong, S.; Nyarko, B.J.B.

    2010-01-01

    PARET/ANL(Version 7.3 of 2007) thermal-hydraulic code was used to perform transient analysis of the Ghana Research Reactor-1.The reactivities inserted were 2.1mk and 4mk.The peak power of 5.81kW was obtained for 2.1 mk insertion whereas the peak power for 4mk insertion of reactivity was 92.32kW.These results compare closely with experiments and theoretical studies conducted previously.

  17. Referencing cross-reactivity of detection antibodies for protein array experiments [version 1; referees: 1 approved, 2 approved with reservations

    Directory of Open Access Journals (Sweden)

    Darragh Lemass

    2016-01-01

    Full Text Available Protein arrays are frequently used to profile antibody repertoires in humans and animals. High-throughput protein array characterisation of complex antibody repertoires requires a platform-dependent, lot-to-lot validation of secondary detection antibodies. This article details the validation of an affinity-isolated anti-chicken IgY antibody produced in rabbit and a goat anti-rabbit IgG antibody conjugated with alkaline phosphatase using protein arrays consisting of 7,390 distinct human proteins. Probing protein arrays with secondary antibodies in absence of chicken serum revealed non-specific binding to 61 distinct human proteins. The cross-reactivity of the tested secondary detection antibodies points towards the necessity of platform-specific antibody characterisation studies for all secondary immunoreagents. Secondary antibody characterisation using protein arrays enables generation of reference lists of cross-reactive proteins, which can be then excluded from analysis in follow-up experiments. Furthermore, making such cross-reactivity lists accessible to the wider research community may help to interpret data generated by the same antibodies in applications not related to protein arrays such as immunoprecipitation, Western blots or other immunoassays.

  18. The H2 + + He proton transfer reaction: quantum reactive differential cross sections to be linked with future velocity mapping experiments

    Science.gov (United States)

    Hernández Vera, Mario; Wester, Roland; Gianturco, Francesco Antonio

    2018-01-01

    We construct the velocity map images of the proton transfer reaction between helium and molecular hydrogen ion {{{H}}}2+. We perform simulations of imaging experiments at one representative total collision energy taking into account the inherent aberrations of the velocity mapping in order to explore the feasibility of direct comparisons between theory and future experiments planned in our laboratory. The asymptotic angular distributions of the fragments in a 3D velocity space is determined from the quantum state-to-state differential reactive cross sections and reaction probabilities which are computed by using the time-independent coupled channel hyperspherical coordinate method. The calculations employ an earlier ab initio potential energy surface computed at the FCI/cc-pVQZ level of theory. The present simulations indicate that the planned experiments would be selective enough to differentiate between product distributions resulting from different initial internal states of the reactants.

  19. Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment

    Science.gov (United States)

    McKnight, Diane M.; Tate, C.M.; Andrews, E.D.; Niyogi, D.K.; Cozzetto, K.; Welch, K.; Lyons, W.B.; Capone, D.G.

    2007-01-01

    The McMurdo Dry Valleys of Antarctica contain many glacial meltwater streams that flow for 6 to 12??weeks during the austral summer and link the glaciers to the lakes on the valley floors. Dry valley streams gain solutes longitudinally through weathering reactions and microbial processes occurring in the hyporheic zone. Some streams have thriving cyanobacterial mats. In streams with regular summer flow, the mats are freeze-dried through the winter and begin photosynthesizing with the onset of flow. To evaluate the longer term persistence of cyanobacterial mats, we diverted flow to an abandoned channel, which had not received substantial flow for approximately two decades. Monitoring of specific conductance showed that for the first 3??years after the diversion, the solute concentrations were greater in the reactivated channel than in most other dry valley streams. We observed that cyanobacterial mats became abundant in the reactivated channel within a week, indicating that the mats had been preserved in a cryptobiotic state in the channel. Over the next several years, these mats had high rates of productivity and nitrogen fixation compared to mats from other streams. Experiments in which mats from the reactivated channel and another stream were incubated in water from both of the streams indicated that the greater solute concentrations in the reactivated channel stimulated net primary productivity of mats from both streams. These stream-scale experimental results indicate that the cryptobiotic preservation of cyanobacterial mats in abandoned channels in the dry valleys allows for rapid response of these stream ecosystems to climatic and geomorphological change, similar to other arid zone stream ecosystems. ?? 2006 Elsevier B.V. All rights reserved.

  20. Heterogeneous computation tests of both substitution and reactivity worth experiments in the RB-3 reactor

    International Nuclear Information System (INIS)

    Broccoli, U.; Cambi, G.; Vanossi, A.; Zapellini, G.

    1977-01-01

    This report presents the results of several experiments carried out in the D 2 O-moderated RB-3 reactors at the CNEN's Laboratory of Montecuccolino, Bologna. The experiments referred to are either fuel-element substitution experiments or interstitial absorber experiments and were performed during the period 1972-1974. The results of measurements are compared with those obtained by means of computational procedure based on some ''cell'' codes coupled with heterogeneous codes. (authors)

  1. What makes ecological systems reactive?

    Science.gov (United States)

    Snyder, Robin E

    2010-06-01

    Although perturbations from a stable equilibrium must ultimately vanish, they can grow initially, and the maximum initial growth rate is called reactivity. Reactivity thus identifies systems that may undergo transient population surges or drops in response to perturbations; however, we lack biological and mathematical intuition about what makes a system reactive. This paper presents upper and lower bounds on reactivity for an arbitrary linearized model, explores their strictness, and discusses their biological implications. I find that less stable systems (i.e. systems with long transients) have a smaller possible range of reactivities for which no perturbations grow. Systems with more species have a higher capacity to be reactive, assuming species interactions do not weaken too rapidly as the number of species increases. Finally, I find that in discrete time, reactivity is determined largely by mean interaction strength and neither discrete nor continuous time reactivity are sensitive to food web topology. 2010 Elsevier Inc. All rights reserved.

  2. Experiment program and results of the TRACY

    International Nuclear Information System (INIS)

    Ogawa, K.; Nakajima, K.; Aizawa, E.; Arishima, H.; Morita, T.; Sakuraba, K.; Takahashi, T.; Ohno, A.

    1998-01-01

    JAERI started supercritical experiments with low enriched uranium nitrate solution with the TRACY in NUCEF. The purpose of the TRACY is to obtain the data on a postulated critical accident phenomena such as power, total number of fissions. In a supercritical experiment, excess reactivity can be inserted by withdrawal of a transient rod or continuous feed of the solution fuel. The TRACY carried out 77 runs including 26 supercritical experiments by the end of 1997. In the transient experiment with reactivity insertion of about 3$, the peak power and the maximum pressure of the core were obtained 1020 MW and 0.50 MPa, respectively. (author)

  3. Experiment data report for Test RIA 1-2 (Reactivity Initiated Accident Test Series)

    International Nuclear Information System (INIS)

    Zimmermann, C.L.; White, C.E.; Evans, R.P.

    1979-06-01

    Recorded test data are presented for the second of six planned tests in the Reactivity Initiated Accident (RIA) Test Series I, Test RIA 1-2. This test, conducted at the Power Burst Facility, had the following objectives: (1) characterize the response of preirradiated fuel rods during an RIA event conducted at boiling water reactor hot-startup conditions; and (2) evaluate the effect of rod internal pressure on preirradiated fuel rod response during an RIA event. The data from Test RIA 1-2 are graphed in engineering units and have been appraised for quality and validity. These uninterpreted data are presented for use in the nuclear fuel behavior research field before detailed analysis and interpretation have been completed

  4. Correction for the time dependent inner filter effect caused by transient absorption in femtosecond stimulated Raman experiment

    NARCIS (Netherlands)

    Kloz, M.; van Grondelle, R.; Kennis, J.T.M.

    2012-01-01

    Femtosecond stimulated Raman spectroscopy (FSRS) is a promising multiple-pulse ultrafast spectroscopic tool whose simplest form utilizes an actinic pump, a Raman pump and a continuum probe. Here, we report that the transient absorption generated by the actinic pulse modulates the overall magnitude

  5. Prevalence of Ex Vivo High On-treatment Platelet Reactivity on Antiplatelet Therapy after Transient Ischemic Attack or Ischemic Stroke on the PFA-100(®) and VerifyNow(®).

    LENUS (Irish Health Repository)

    Kinsella, Justin A

    2012-09-12

    BACKGROUND: The prevalence of ex vivo high on-treatment platelet reactivity (HTPR) to commonly prescribed antiplatelet regimens after transient ischemic attack (TIA) or ischemic stroke is uncertain. METHODS: Platelet function inhibition was simultaneously assessed with modified light transmission aggregometry (VerifyNow; Accumetrics Inc, San Diego, CA) and with a moderately high shear stress platelet function analyzer (PFA-100; Siemens Medical Solutions USA, Inc, Malvern, PA) in a pilot, cross-sectional study of TIA or ischemic stroke patients. Patients were assessed on aspirin-dipyridamole combination therapy (n = 51) or clopidogrel monotherapy (n = 25). RESULTS: On the VerifyNow, HTPR on aspirin was identified in 4 of 51 patients (8%) on aspirin-dipyridamole combination therapy (≥550 aspirin reaction units on the aspirin cartridge). Eleven of 25 (44%) patients had HTPR on clopidogrel (≥194 P2Y12 reaction units on the P2Y12 cartridge). On the PFA-100, 21 of 51 patients (41%) on aspirin-dipyridamole combination therapy had HTPR on the collagen-epinephrine (C-EPI) cartridge. Twenty-three of 25 patients (92%) on clopidogrel had HTPR on the collagen-adenosine diphosphate (C-ADP) cartridge. The proportion of patients with antiplatelet HTPR was lower on the VerifyNow than PFA-100 in patients on both regimens (P < .001). CONCLUSIONS: The prevalence of ex vivo antiplatelet HTPR after TIA or ischemic stroke is markedly influenced by the method used to assess platelet reactivity. The PFA-100 C-ADP cartridge is not sensitive at detecting the antiplatelet effects of clopidogrel ex vivo. Larger prospective studies with the VerifyNow and with the PFA-100 C-EPI and recently released Innovance PFA P2Y cartridges (Siemens Medical Solutions USA, Inc) in addition to newer tests of platelet function are warranted to assess whether platelet function monitoring predicts clinical outcome in ischemic cerebrovascular disease.

  6. BISON Modeling of Reactivity-Initiated Accident Experiments in a Static Environment

    Energy Technology Data Exchange (ETDEWEB)

    Folsom, Charles P.; Jensen, Colby B.; Williamson, Richard L.; Woolstenhulme, Nicolas E.; Ban, Heng; Wachs, Daniel M.

    2016-09-01

    In conjunction with the restart of the TREAT reactor and the design of test vehicles, modeling and simulation efforts are being used to model the response of Accident Tolerant Fuel (ATF) concepts under reactivity insertion accident (RIA) conditions. The purpose of this work is to model a baseline case of a 10 cm long UO2-Zircaloy fuel rodlet using BISON and RELAP5 over a range of energy depositions and with varying reactor power pulse widths. The results show the effect of varying the pulse width and energy deposition on both thermal and mechanical parameters that are important for predicting failure of the fuel rodlet. The combined BISON/RELAP5 model captures coupled thermal and mechanical effects on the fuel-to-cladding gap conductance, cladding-to-coolant heat transfer coefficient and water temperature and pressure that would not be capable in each code individually. These combined effects allow for a more accurate modeling of the thermal and mechanical response in the fuel rodlet and thermal-hydraulics of the test vehicle.

  7. Kinetics of Reactive Fronts in Porous Media: quantification through a laboratory experiment

    Science.gov (United States)

    De Anna, P.; Jimenez-Martinez, J.; Turuban, R.; Tabuteau, H.; Derrien, M.; Le Borgne, T.; Meheust, Y.

    2013-12-01

    The kinetics of reaction fronts in heterogeneous flows is tightly linked to the mixing dynamics governed by the combined action of stretching, diffusion and dispersion. Focusing on porous media flows, with a new experimental setup we show that the invading solute is organized into stretched lamellae, whose deformation and coalescence control the effective reaction kinetics of the mixing limited bimolecular reaction A + B --> C. While the classic advection-dispersion theory predicts a scaling of the cumulative product mass of C as t^(0.5), we observe two distinct kinetics regimes, one characterized by the stretching and the other by the coalescence of the invading lamellae, in which the mass of C scales faster than t^(0.5). The proposed experimental set up allows for direct quantification of mixing and reactive transport in porous media with a high spatial resolution, at the pore scale. The analogous two dimensional porous medium consists in a Hele-Shaw cell containing a single layer of cylindrical solid grains built by soft lithography. On the one hand, the measurement of the local, intra-pore, conservative concentration field is done using a fluorescent tracer. On the other hand, considering a fast bimolecular advection-dispersion reaction A + B --> C occurring as A displaces B, we quantify the reaction kinetics from the spatially-resolved measurement of the pore scale reaction rate, using a chemiluminescent reaction.

  8. An Open-Source, Low-Cost Robot for Performing Reactive Liquid Handling Experiments

    DEFF Research Database (Denmark)

    Nejatimoharrami, Farzad; Faina, Andres; Støy, Kasper

    vessels in the middle, and 3) a camera as the sensing system at the bottom, providing a view of the experiment. From the raw camera image experiment specific data such as droplet size, position, speed, number, color, and shape are calculated. The computer vision system has an accuracy of 4% for droplet......Bot's application domain is extendable owing to a modular design of hardware, and open source software. Evobot's modular design enables support for different modules, e.g. syringe modules for liquid handling, grippers to reposition reaction vessels or dispose of them, sensor modules including temperature, pH, etc...

  9. Oxidation of volatile organic compound vapours by potassium permanganate in a horizontal permeable reactive barrier under unsaturated conditions: experiments and modeling

    NARCIS (Netherlands)

    Ghareh Mahmoodlu, Mojtaba|info:eu-repo/dai/nl/357287746

    2014-01-01

    In this research we evaluated the potential of using solid potassium permanganate to create a horizontal permeable reactive barrier (HPRB) for oxidizing VOC vapours in the unsaturated zone. We have performed batch experiments, short column, and long column experiments, and have fully analyzed the

  10. Multiphase, multicomponent simulations and experiments of reactive flow, relevant for combining geologic CO2 sequestration with geothermal energy capture

    Science.gov (United States)

    Saar, Martin O.

    2011-11-01

    Understanding the fluid dynamics of supercritical carbon dioxide (CO2) in brine- filled porous media is important for predictions of CO2 flow and brine displacement during geologic CO2 sequestration and during geothermal energy capture using sequestered CO2 as the subsurface heat extraction fluid. We investigate multiphase fluid flow in porous media employing particle image velocimetry experiments and lattice-Boltzmann fluid flow simulations at the pore scale. In particular, we are interested in the motion of a drop (representing a CO2 bubble) through an orifice in a plate, representing a simplified porous medium. In addition, we study single-phase/multicomponent reactive transport experimentally by injecting water with dissolved CO2 into rocks/sediments typically considered for CO2 sequestration to investigate how resultant fluid-mineral reactions modify permeability fields. Finally, we investigate numerically subsurface CO2 and heat transport at the geologic formation scale.

  11. Simulation of LOFT anticipated-transient experiments L6-1, L6-2, and L6-3 using TRAC-PF1/MOD1

    International Nuclear Information System (INIS)

    Sahota, M.S.

    1984-01-01

    Anticipated-transient experiments L6-1, L6-2, and L6-3, performed at the Loss-of-fluid Test (LOFT) facility, are analyzed using the latest released version of the Transient Reactor Analysis Code (TRAC-PF1/MOD1). The results are used to assess TRAC-PF1/MOD1 trip and control capabilities, and predictions of thermal-hydraulic phenomena during slow transients. Test L6-1 simulated a loss-of-stream load in a large pressurized-water reactor (PWR), and was initiated by closing the main steam-flow control valve (MSFCV) at its maximum rate, which reduced the heat removal from the secondary-coolant system and increased the primary-coolant system pressure that initiated a reactor scram. Test L6-2 simulated a loss-of-primary coolant flow in a large PWR, and was initiated by tripping the power to the primary-coolant pumps (PCPs) allowing the pumps to coast down. The reduced primary-coolant flow caused a reactor scram. Test L6-3 simulated an excessive-load increase incident in a large PWR, and was initiated by opening the MSFCV at its maximum rate, which increased the heat removal from the secondary-coolant system and decreased the primary-coolant system pressure that initiated a reactor scram. The TRAC calculations accurately predict most test events. The test data and the calculated results for most parameters of interest also agree well

  12. Self-propagating exothermic reaction analysis in Ti/Al reactive films using experiments and computational fluid dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Seema, E-mail: seema.sen@tu-ilmenau.de [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Lake, Markus; Kroppen, Norman; Farber, Peter; Wilden, Johannes [Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Schaaf, Peter [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany)

    2017-02-28

    Highlights: • Development of nanoscale Ti/Al multilayer films with 1:1, 1:2 and 1:3 molar ratios. • Characterization of exothermic reaction propagation by experiments and simulation. • The reaction velocity depends on the ignition potentials and molar ratios of the films. • Only 1Ti/3Al films exhibit the unsteady reaction propagation with ripple formation. • CFD simulation shows the time dependent atom mixing and temperature flow during exothermic reaction. - Abstract: This study describes the self-propagating exothermic reaction in Ti/Al reactive multilayer foils by using experiments and computational fluid dynamics simulation. The Ti/Al foils with different molar ratios of 1Ti/1Al, 1Ti/2Al and 1Ti/3Al were fabricated by magnetron sputtering method. Microstructural characteristics of the unreacted and reacted foils were analyzed by using electronic and atomic force microscopes. After an electrical ignition, the influence of ignition potentials on reaction propagation has been experimentally investigated. The reaction front propagates with a velocity of minimum 0.68 ± 0.4 m/s and maximum 2.57 ± 0.6 m/s depending on the input ignition potentials and the chemical compositions. Here, the 1Ti/3Al reactive foil exhibits both steady state and unsteady wavelike reaction propagation. Moreover, the numerical computational fluid dynamics (CFD) simulation shows the time dependent temperature flow and atomic mixing in a nanoscale reaction zone. The CFD simulation also indicates the potentiality for simulating exothermic reaction in the nanoscale Ti/Al foil.

  13. Transients: The regulator's view

    International Nuclear Information System (INIS)

    Sheron, B.W.; Speis, T.P.

    1984-01-01

    This chapter attempts to clarify the basis for the regulator's concerns for transient events. Transients are defined as both anticipated operational occurrences and postulated accidents. Recent operational experience, supplemented by improved probabilistic risk analysis methods, has demonstrated that non-LOCA transient events can be significant contributors to overall risk. Topics considered include lessons learned from events and issues, the regulations governing plant transients, multiple failures, different failure frequencies, operator errors, and public pressure. It is concluded that the formation of Owners Groups and Regulatory Response Groups within the owners groups are positive signs of the industry's concern for safety and responsible dealing with the issues affecting both the US NRC and the industry

  14. Characterization of reactive tracers for C-wells field experiments 1: Electrostatic sorption mechanism, lithium

    International Nuclear Information System (INIS)

    Fuentes, H.R.; Polzer, W.L.; Essington, E.H.; Newman, B.D.

    1989-11-01

    Lithium (Li + ) was introduced as lithium bromide (LiBr), as a retarded tracer for experiments in the C-wells complex at Yucca Mountain, Nevada Test Site, Nevada. The objective was to evaluate the potential of lithium to sorb predominately by physical forces. lithium was selected as a candidate tracer on the basis of high solubility, good chemical and biological stability, and relatively low sorptivity; lack of bioaccumulation and exclusion as a priority pollutant in pertinent federal environmental regulations; good analytical detectability and low natural background concentrations; and a low cost Laboratory experiments were performed with suspensions of Prow Pass cuttings from drill hole UE-25p number-sign 1 at depths between 549 and 594 m in J-13 water at a pH of approximately 8 and in the temperature range of 25 degree C to 45 degree C. Batch equilibrium and kinetics experiments were performed; estimated thermodynamic constants, relative behavior between adsorption and desorption, and potentiometric studies provided information to infer the physical nature of lithium sorption

  15. Chernobyl reactor transient simulation study

    International Nuclear Information System (INIS)

    Gaber, F.A.; El Messiry, A.M.

    1988-01-01

    This paper deals with the Chernobyl nuclear power station transient simulation study. The Chernobyl (RBMK) reactor is a graphite moderated pressure tube type reactor. It is cooled by circulating light water that boils in the upper parts of vertical pressure tubes to produce steam. At equilibrium fuel irradiation, the RBMK reactor has a positive void reactivity coefficient. However, the fuel temperature coefficient is negative and the net effect of a power change depends upon the power level. Under normal operating conditions the net effect (power coefficient) is negative at full power and becomes positive under certain transient conditions. A series of dynamic performance transient analysis for RBMK reactor, pressurized water reactor (PWR) and fast breeder reactor (FBR) have been performed using digital simulator codes, the purpose of this transient study is to show that an accident of Chernobyl's severity does not occur in PWR or FBR nuclear power reactors. This appears from the study of the inherent, stability of RBMK, PWR and FBR under certain transient conditions. This inherent stability is related to the effect of the feed back reactivity. The power distribution stability in the graphite RBMK reactor is difficult to maintain throughout its entire life, so the reactor has an inherent instability. PWR has larger negative temperature coefficient of reactivity, therefore, the PWR by itself has a large amount of natural stability, so PWR is inherently safe. FBR has positive sodium expansion coefficient, therefore it has insufficient stability it has been concluded that PWR has safe operation than FBR and RBMK reactors

  16. Preliminary characterization of materials for a reactive transport model validation experiment

    International Nuclear Information System (INIS)

    Siegel, M.D.; Ward, D.B.; Cheng, W.C.; Bryant, C.; Chocas, C.S.; Reynolds, C.G.

    1993-01-01

    The geochemical properties of a porous sand and several tracers (Ni, Br, and Li) have been characterized for use in a caisson experiment designed to validate sorption models used in models of inactive transport. The surfaces of the sand grains have been examined by a combination of techniques including potentiometric titration, acid leaching, optical microscopy, and scanning electron microscopy with energy-dispersive spectroscopy. The surface studies indicate the presence of small amounts of carbonate, kaolinite and iron-oxyhydroxides. Adsorption of nickel, lithium and bromide by the sand was measured using batch techniques. Bromide was not sorbed by the sand. A linear (K d ) or an isotherm sorption model may adequately describe transport of Li; however, a model describing the changes of pH and the concentrations of other solution species as a function of time and position within the caisson and the concomitant effects on Ni sorption may be required for accurate predictions of nickel transport

  17. Impact of CO2 injection protocol on fluid-solid reactivity: high-pressure and temperature microfluidic experiments in limestone

    Science.gov (United States)

    Jimenez-Martinez, Joaquin; Porter, Mark; Carey, James; Guthrie, George; Viswanathan, Hari

    2017-04-01

    Geological sequestration of CO2 has been proposed in the last decades as a technology to reduce greenhouse gas emissions to the atmosphere and mitigate the global climate change. However, some questions such as the impact of the protocol of CO2 injection on the fluid-solid reactivity remain open. In our experiments, two different protocols of injection are compared at the same conditions (8.4 MPa and 45 C, and constant flow rate 0.06 ml/min): i) single phase injection, i.e., CO2-saturated brine; and ii) simultaneous injection of CO2-saturated brine and scCO2. For that purpose, we combine a unique high-pressure/temperature microfluidics experimental system, which allows reproducing geological reservoir conditions in geo-material substrates (i.e., limestone, Cisco Formation, Texas, US) and high resolution optical profilometry. Single and multiphase flow through etched fracture networks were optically recorded with a microscope, while processes of dissolution-precipitation in the etched channels were quantified by comparison of the initial and final topology of the limestone micromodels. Changes in hydraulic conductivity were quantified from pressure difference along the micromodel. The simultaneous injection of CO2-saturated brine and scCO2, reduced the brine-limestone contact area and also created a highly heterogeneous velocity field (i.e., low velocities regions or stagnation zones, and high velocity regions or preferential paths), reducing rock dissolution and enhancing calcite precipitation. The results illustrate the contrasting effects of single and multiphase flow on chemical reactivity and suggest that multiphase flow by isolating parts of the flow system can enhance CO2 mineralization.

  18. Fuel pin behavior under slow ramp-type transient-overpower conditions in the CABRI-FAST experiments

    International Nuclear Information System (INIS)

    Fukano, Yoshitaka; Onoda, Yuichi; Sato, Ikken; Charpenel, Jean

    2009-01-01

    In the CABRI-FAST experimental program, four in-pile tests were performed with slow power-ramp-type transient-overpower conditions (called hereafter as 'slow TOP') to study transient fuel pin behavior under inadvertent control rod withdrawal events in liquid metal cooled fast breeder reactors. Annular-pellet fuel pins were used in three tests, while a solid-pellet fuel pin was used in the other test. All of these pins were pre-irradiated in Phenix. The slow TOP test with a solid-pellet fuel pin was realized as a comparatory test against an existing test (E12) in the CABRI-2 program. In the CABRI-FAST test (BCF1), a power ramp rate of 3% Po/s was applied, while in the CABRI-2 test, 1% Po/s was adopted. Moreover, overpower condition was maintained for a few seconds beyond the observed pin failure in the BCF1 test. In spite of the different power ramp rates, evaluated fuel thermal conditions at the observed failure time are quite similar. The continued overpower condition in the BCF1 test resulted in gradual degradation of the pin structure providing information effective for evaluation of various accident scenarios. Three slow TOP tests with the annular fuel in the CABRI-FAST program resulted in no pin failure showing high failure threshold. Based on post-test examination data and a theoretical evaluation, it was concluded that intra-pin free spaces, such as central hole, macroscopic cracks and fuel-cladding gap effectively mitigated fuel cladding mechanical interaction. It was also clarified that cavity pressurization became effective only in case of very large amount of fuel melting. Furthermore, such cavity pressurization was effectively mitigated by a molten-fuel squirting into the upper blanket region pushing the blanket pellets upward. These CABRI FAST slow TOP tests, in combination with the existing CABRI and TREAT tests, provided an extended slow TOP test database with various fuel and transient conditions. (author)

  19. Transient analysis for resolving safety issues

    International Nuclear Information System (INIS)

    Chao, J.; Layman, W.

    1987-01-01

    The Nuclear Safety Analysis Center (NSAC) has a Generic Safety Analysis Program to help resolve high priority generic safety issues. This paper describes several high priority safety issues considered at NSAC and how they were resolved by transient analysis using thermal hydraulics and neutronics codes. These issues are pressurized thermal shock (PTS), anticipated transients without scram (ATWS), steam generator tube rupture (SGTR), and reactivity transients in light of the Chernobyl accident

  20. Double shock experiments and reactive flow modeling on LX-17 to understand the reacted equation of state

    International Nuclear Information System (INIS)

    Vandersall, Kevin S; Garcia, Frank; Fried, Laurence E; Tarver, Craig M

    2014-01-01

    Experimental data from measurements of the reacted state of an energetic material are desired to incorporate reacted states in modeling by computer codes. In a case such as LX-17 (92.5% TATB and 7.5% Kel-F by weight), where the time dependent kinetics of reaction is still not fully understood and the reacted state may evolve over time, this information becomes even more vital. Experiments were performed to measure the reacted state of LX-17 using a double shock method involving the use of two flyer materials (with known properties) mounted on the projectile that send an initial shock through the material close to or above the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. By measuring the parameters of the first and second shock waves, information on the reacted state can be obtained. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments.

  1. Monte Carlo analysis of experiments on the reactivity temperature coefficient for UO2 and MOX light water moderated lattices

    International Nuclear Information System (INIS)

    Erradi, L.; Chetaine, A.; Chakir, E.; Kharchaf, A.; Elbardouni, T.; Elkhoukhi, T.

    2005-01-01

    In a previous work, we have analysed the main French experiments available on the reactivity temperature coefficient (RTC): CREOLE and MISTRAL experiments. In these experiments, the RTC has been measured in both UO 2 and UO 2 -PuO 2 PWR type lattices. Our calculations, using APOLLO2 code with CEA93 library based on JEF2.2 evaluation, have shown that the calculation error in UO 2 lattices is less than 1 pcm/C degrees which is considered as the target accuracy. On the other hand the calculation error in the MOX lattices is more significant in both low and high temperature ranges: an average error of -2 ± 0.5 pcm/C degrees is observed in low temperatures and an error of +3 ± 2 pcm/C degrees is obtained for temperatures higher than 250 C degrees. In the present work, we analysed additional experimental benchmarks on the RTC of UO 2 and MOX light water moderated lattices. To analyze these benchmarks and with the aim of minimizing uncertainties related to modelling of the experimental set up, we chose the Monte Carlo method which has the advantage of taking into account in the most exact manner the geometry of the experimental configurations. This analysis shows for the UO 2 lattices, a maximum experiment-calculation deviation of about 0,7 pcm/C degrees, which is below the target accuracy for this type of lattices. For the KAMINI experiment, which relates to the measurement of the RTC in a light water moderated lattice using U-233 as fuel our analysis shows that the ENDF/B6 library gives the best result, with an experiment-calculation deviation of the order of -0,16 pcm/C degrees. The analysis of the benchmarks using MOX fuel made it possible to highlight a discrepancy between experiment and calculation on the RTC of about -0.7 pcm/C degrees (for a range of temperatures going from 20 to 248 C degrees) and -1,2 pcm/C degrees (for a range of temperatures going from 20 to 80 C degrees). This result, in particular the tendency which has the error to decrease when the

  2. Transverse heat transfer coefficient in the dual channel ITER TF CICCs Part II. Analysis of transient temperature responses observed during a heat slug propagation experiment

    Science.gov (United States)

    Lewandowska, Monika; Herzog, Robert; Malinowski, Leszek

    2015-01-01

    A heat slug propagation experiment in the final design dual channel ITER TF CICC was performed in the SULTAN test facility at EPFL-CRPP in Villigen PSI. We analyzed the data resulting from this experiment to determine the equivalent transverse heat transfer coefficient hBC between the bundle and the central channel of this cable. In the data analysis we used methods based on the analytical solutions of a problem of transient heat transfer in a dual-channel cable, similar to Renard et al. (2006) and Bottura et al. (2006). The observed experimental and other limits related to these methods are identified and possible modifications proposed. One result from our analysis is that the hBC values obtained with different methods differ by up to a factor of 2. We have also observed that the uncertainties of hBC in both methods considered are much larger than those reported earlier.

  3. Monte Carlo analysis of experiments on the reactivity temperature coefficient for UO2 and MOX light water moderated lattices

    International Nuclear Information System (INIS)

    Chakir, E.; Erradi, L.; Bardouni, T El.; Khoukhi, T El.; Boukhal, H.; Meroun, O.; Bakkari, B El

    2007-01-01

    Full text: In a previous work, we have analysed the main french experiments available on the reactivity temperature coefficient (RTC) : CREAOLE and Mistral experiments. In these experiments, the RTC has been measured in both UO2 and UO2-PuO2 PWR type lattices. Our calculations, using APPOLO2 code with CEA93 library based on JEF2.2 evaluation, have shown that the calculation error in UO2 lattices is less than 1 pcm/Deg C which is considered as the target accuracy. On the other hand the calculation error in the MOX lattices is more significant in both low and high temperature ranges : an average error of -2 ± 0.5 pcm/Deg C is observed in low temperatures and an error of +3±2 pcm/Deg C is obtained for temperature higher than 250Deg C. In the present work, we analysed additional experimental benchmarks on the RTC of UO2 and MOX light water moderated lattices. To analyze these benchmarks and with the aim of minimizing uncertainties related to modelling of the experimental set up, we chose the Monte Carlo Method which has the advantage of taking into account in the most exact manner the geometry of the experimental configurations. Thus we have used the code MCNP5, for its recognized power and its availability. This analysis shows for the UO2 lattices, an average experiment-calculation deviation of about 0,5 pcm/Deg C, which is largely below the target accuracy for this type of lattices, that we estimate at approximately 1 pcm/Deg C. For the KAMINI experiment, which relates to the measurement of the RTC in light water moderated lattice using U-233 as fuel our analysis shows that the Endf/B6 library gives the best result, with an experiment -calculation deviation of the order of -0,16 pcm/Deg C. The analysis of the benchmarks using MOX fuel made it possible to highlight a discrepancy between experiment and calculation on the RTC of about -0.7pcm/Deg C ( for a range of temperature going from 20 to 248 Deg C) and -1.2 pcm/Deg C ( for a range of temperature going from 20 to

  4. Reactive solute transport in acidic streams

    Science.gov (United States)

    Broshears, R.E.

    1996-01-01

    Spatial and temporal profiles of Ph and concentrations of toxic metals in streams affected by acid mine drainage are the result of the interplay of physical and biogeochemical processes. This paper describes a reactive solute transport model that provides a physically and thermodynamically quantitative interpretation of these profiles. The model combines a transport module that includes advection-dispersion and transient storage with a geochemical speciation module based on MINTEQA2. Input to the model includes stream hydrologic properties derived from tracer-dilution experiments, headwater and lateral inflow concentrations analyzed in field samples, and a thermodynamic database. Simulations reproduced the general features of steady-state patterns of observed pH and concentrations of aluminum and sulfate in St. Kevin Gulch, an acid mine drainage stream near Leadville, Colorado. These patterns were altered temporarily by injection of sodium carbonate into the stream. A transient simulation reproduced the observed effects of the base injection.

  5. LMFBR. Off normal, transient test facilities and programs in the USA

    International Nuclear Information System (INIS)

    Herbst, R.J.

    1985-01-01

    The United States fast breeder reactor development program has included operational transient analyses and experiments to verify the predicted performance of core components. Operational transient testing has focused on off-normal operation during Plant Protection System terminated transient-overpower events. In-pile and out-of-pile tests have been used to simulate predicted thermal and mechanical strain cycles and measure component response. The spectrum of reactivity ramp rates investigated in TOP tests has recently been expanded to include rates of less than $0.1/s. These slow ramp rate studies are being done in cooperation with the Japanese. The US has also cooperated with the UK in the transient testing of Prototype Fast Reactor fuel pins

  6. Validation of coupled Relap5-3D code in the analysis of RBMK-1500 specific transients

    International Nuclear Information System (INIS)

    Evaldas, Bubelis; Algirdas, Kaliatka; Eugenijus, Uspuras

    2003-01-01

    This paper deals with the modelling of RBMK-1500 specific transients taking place at Ignalina NPP. These transients include: measurements of void and fast power reactivity coefficients, change of graphite cooling conditions and reactor power reduction transients. The simulation of these transients was performed using RELAP5-3D code model of RBMK-1500 reactor. At the Ignalina NPP void and fast power reactivity coefficients are measured on a regular basis and, based on the total reactor power, reactivity, control and protection system control rods positions and the main circulation circuit parameter changes during the experiments, the actual values of these reactivity coefficients are determined. Graphite temperature reactivity coefficient at the plant is determined by changing graphite cooling conditions in the reactor cavity. This type of transient is very unique and important from the gap between fuel channel and the graphite bricks model validation point of view. The measurement results, obtained during this transient, allowed to determine the thermal conductivity coefficient for this gap and to validate the graphite temperature reactivity feedback model. Reactor power reduction is a regular operation procedure during the entire lifetime of the reactor. In all cases it starts by either a scram or a power reduction signal activation by the reactor control and protection system or by an operator. The obtained calculation results demonstrate reasonable agreement with Ignalina NPP measured data. Behaviours of the separate MCC thermal-hydraulic parameters as well as physical processes are predicted reasonably well to the real processes, occurring in the primary circuit of RBMK-1500 reactor. Reasonable agreement of the measured and the calculated total reactor power change in time demonstrates the correct modelling of the neutronic processes taking place in RBMK- 1500 reactor core. And finally, the performed validation of RELAP5-3D model of Ignalina NPP RBMK-1500

  7. Reactivity accident analysis in MTR cores

    International Nuclear Information System (INIS)

    Waldman, R.M.; Vertullo, A.C.

    1987-01-01

    The purpose of the present work is the analysis of reactivity transients in MTR cores with LEU and HEU fuels. The analysis includes the following aspects: the phenomenology of the principal events of the accident that takes place, when a reactivity of more than 1$ is inserted in a critical core in less than 1 second. The description of the accident that happened in the RA-2 critical facility in September 1983. The evaluation of the accident from different points of view: a) Theoretical and qualitative analysis; b) Paret Code calculations; c) Comparison with Spert I and Cabri experiments and with post-accident inspections. Differences between LEU and HEU RA-2 cores. (Author)

  8. Study on the transient behaviours of MNSR reactor for control rod withdrawal

    International Nuclear Information System (INIS)

    Yang Shunhai

    1995-10-01

    The transient behaviours of Miniature Neutron Source Reactor MNSR are analyzed and calculated with the reactor thermohydraulics RETRAN-02 program and the reactor physics MARIA program. The obtained event sequence and consequence from the calculation are compared with the experiments. The effective resonance integral for study on Doppler effect is taken into account. The reactivity temperature coefficient weighting factors are computed. The transient parameters related to reactor power peaking, coolant inlet temperatures, outlet temperatures and coolant mass flow, etc. are computed and compared with the experimental results. (6 refs., 2 figs., 5 tabs.)

  9. Chemical reactivity of precursor materials during synthesis of glasses used for conditioning high-level radioactive waste: Experiments and models

    International Nuclear Information System (INIS)

    Monteiro, A.

    2012-01-01

    The glass used to store high-level radioactive waste is produced by reaction of a solid waste residue and a glassy precursor (glass frit). The waste residue is first dried and calcined (to lose water and nitrogen respectively), then mixed with the glass frit to enable vitrification at high temperature. In order to obtain a good quality glass of constant composition upon cooling, the chemical reactions between the solid precursors must be complete while in the liquid state, to enable incorporation of the radioactive elements into the glassy matrix. The physical and chemical conditions during glass synthesis (e.g. temperature, relative proportions of frit and calcine, amount of radioactive charge) are typically empirically adjusted to obtain a satisfactory final product. The aim of this work is to provide new insights into the chemical and physical interactions that take place during vitrification and to provide data for a mathematical model that has been developed to simulate the chemical reactions. The consequences of the different chemical reactions that involve solid, liquid and gaseous phases are described (thermal effects, changes in crystal morphology and composition, variations in melt properties and structure). In a first series of experiments, a simplified analogue of the calcine (NaNO 3 -Al 2 O 3 ± MoO 3 /Nd 2 O 3 ) has been studied. In a second series of experiments, the simplified calcines have been reacted with a simplified glass frit (SiO 2 -Na 2 O-B 2 O 3 -Al 2 O 3 ) at high temperature. The results show that crystallization of the calcine may take place before interaction with the glass frit, but that the reactivity with the glass at high temperature is a function of the nature and stoichiometry of the crystalline phases which form at low temperature. The results also highlight how the mixing of the starting materials, the physical properties of the frit (viscosity, glass transition temperature) and the Na 2 O/Al 2 O 3 of the calcine but also its

  10. Learning from anticipated and abnormal plant transients

    International Nuclear Information System (INIS)

    Varnado, B.

    1983-01-01

    A report is given of the American Nuclear Society topical meeting on Anticipated and Abnormal Transients in Light Water Reactors held in Jackson, Wyoming in September 1983. Industry involvement in the evaluation of operating experience, human error contributions, transient management, thermal hydraulic modelling, the role of probabilistic risk assessment and the cost of transient incidents are discussed. (U.K.)

  11. Transient Go: A Mobile App for Transient Astronomy Outreach

    Science.gov (United States)

    Crichton, D.; Mahabal, A.; Djorgovski, S. G.; Drake, A.; Early, J.; Ivezic, Z.; Jacoby, S.; Kanbur, S.

    2016-12-01

    Augmented Reality (AR) is set to revolutionize human interaction with the real world as demonstrated by the phenomenal success of `Pokemon Go'. That very technology can be used to rekindle the interest in science at the school level. We are in the process of developing a prototype app based on sky maps that will use AR to introduce different classes of astronomical transients to students as they are discovered i.e. in real-time. This will involve transient streams from surveys such as the Catalina Real-time Transient Survey (CRTS) today and the Large Synoptic Survey Telescope (LSST) in the near future. The transient streams will be combined with archival and latest image cut-outs and other auxiliary data as well as historical and statistical perspectives on each of the transient types being served. Such an app could easily be adapted to work with various NASA missions and NSF projects to enrich the student experience.

  12. Transient regional climate change: analysis of the summer climate response in a high-resolution, century-scale, ensemble experiment over the continental United States

    Science.gov (United States)

    Diffenbaugh, Noah S.; Ashfaq, Moetasim; Scherer, Martin

    2013-01-01

    Integrating the potential for climate change impacts into policy and planning decisions requires quantification of the emergence of sub-regional climate changes that could occur in response to transient changes in global radiative forcing. Here we report results from a high-resolution, century-scale, ensemble simulation of climate in the United States, forced by atmospheric constituent concentrations from the Special Report on Emissions Scenarios (SRES) A1B scenario. We find that 21st century summer warming permanently emerges beyond the baseline decadal-scale variability prior to 2020 over most areas of the continental U.S. Permanent emergence beyond the baseline annual-scale variability shows much greater spatial heterogeneity, with emergence occurring prior to 2030 over areas of the southwestern U.S., but not prior to the end of the 21st century over much of the southcentral and southeastern U.S. The pattern of emergence of robust summer warming contrasts with the pattern of summer warming magnitude, which is greatest over the central U.S. and smallest over the western U.S. In addition to stronger warming, the central U.S. also exhibits stronger coupling of changes in surface air temperature, precipitation, and moisture and energy fluxes, along with changes in atmospheric circulation towards increased anticylonic anomalies in the mid-troposphere and a poleward shift in the mid-latitude jet aloft. However, as a fraction of the baseline variability, the transient warming over the central U.S. is smaller than the warming over the southwestern or northeastern U.S., delaying the emergence of the warming signal over the central U.S. Our comparisons with observations and the Coupled Model Intercomparison Project Phase 3 (CMIP3) ensemble of global climate model experiments suggest that near-term global warming is likely to cause robust sub-regional-scale warming over areas that exhibit relatively little baseline variability. In contrast, where there is greater

  13. Thermoeconomic optimization of a solar-assisted heat pump based on transient simulations and computer Design of Experiments

    International Nuclear Information System (INIS)

    Calise, Francesco; Dentice d’Accadia, Massimo; Figaj, Rafal Damian; Vanoli, Laura

    2016-01-01

    Highlights: • A polygeneration system for a residential house is presented. • Hybrid photovoltaic/thermal collectors are used, coupled with a solar-assisted heat pump. • An optimization has been performed. • The system is profitable even in the absence of incentives. • A simple pay-back period of about 5 year is achieved. - Abstract: In the paper, a model for the simulation and the optimization of a novel solar trigeneration system is presented. The plant simulation model is designed to supply electricity, space heating or cooling and domestic hot water for a small residential building. The system is based on a solar field equipped with flat-plate photovoltaic/thermal collectors, coupled with a water-to-water electric heat pump/chiller. The electrical energy produced by the hybrid collectors is entirely supplied to the building. During the winter, the thermal energy available from the solar field is used as a heat source for the evaporator of the heat pump and/or to produce domestic hot water. During the summer, the heat pump operates in cooling mode, coupled with a closed circuit cooling tower, providing space cooling for the building, and the hot water produced by the collectors is only used to produce domestic hot water. For such a system, a dynamic simulation model was developed in TRNSYS environment, paying special attention to the dynamic simulation of the building, too. The system was analyzed from an energy and economic point of view, considering different time bases. In order to minimize the pay-back period, an optimum set of the main design/control parameters was obtained by means of a sensitivity analysis. Simultaneously, a computer-based Design of Experiment procedure was implemented, aiming at calculating the optimal set of design parameters, using both energy and economic objective functions. The results showed that thermal and electrical efficiencies are above 40% and 10%, respectively. The coefficient of performance of the reversible heat

  14. Maximization of primary energy savings of solar heating and cooling systems by transient simulations and computer design of experiments

    International Nuclear Information System (INIS)

    Calise, F.; Palombo, A.; Vanoli, L.

    2010-01-01

    In this paper, the simulation of the performance of solar-assisted heating and cooling systems is analyzed. Three different plant layouts are considered: (i) the first one consists of evacuated solar collectors and a single-stage LiBr-H 2 O absorption chiller; here in order to integrate the system in case of insufficient solar radiation, an electric water-cooled chiller is activated; (ii) configuration of the secondly considered system is similar to the first one, but the absorption chiller and the solar collector area are sized for balancing about 30% of the building cooling load only; (iii) the layout of the thirdly considered system differs from the first one since the auxiliary electric chiller is replaced by a gas-fired heater. Such system configurations also include: circulation pumps, storage tanks, feedback controllers, mixers, diverters and on/off hysteresis controllers. All such devices are modelled for maximizing the system energy efficiency. In order to simulate the systems' performance for dynamic heating/cooling loads, a single-lumped capacitance building is also modelled and implemented in the computer code. A cost model is also developed in order to calculate the systems' operating and capital costs. All the models and the relative simulations are carried out by TRNSYS. A design of experiment procedure is also included. By such tool the effects of the system operating parameters' variation on the relative energy efficiency are analyzed. In addition, the set of synthesis/design variables maximizing the system's energetic performance can be also identified. The annual primary energy saving is chosen as the optimization objective function, whereas collector slope, pump flows, set-point temperatures and tank volume are selected as optimizing system design variables. A case study was developed for an office building located in South Italy. Here, the energetic and the economic analysis for all the three considered system layouts are carried out. The

  15. Nuclear power plant transients: where are we

    International Nuclear Information System (INIS)

    Majumdar, D.

    1984-05-01

    This document is in part a postconference review and summary of the American Nuclear Society sponsored Anticipated and Abnormal Plant Transients in Light Water Reactors Conference held in Jackson, Wyoming, September 26-29, 1983, and in part a reflection upon the issues of plant transients and their impact on the viability of nuclear power. This document discusses state-of-the-art knowledge, deficiencies, and future directions in the plant transients area as seen through this conference. It describes briefly what was reported in this conference, emphasizes areas where it is felt there is confidence in the nuclear industry, and also discusses where the experts did not have a consensus. Areas covered in the document include major issues in operational transients, transient management, transient events experience base, the status of the analytical tools and their capabilities, probabilistic risk assessment applications in operational transients, and human factors impact on plant transients management

  16. Are addiction-related memories malleable by working memory competition? Transient effects on memory vividness and nicotine craving in a randomized lab experiment.

    Science.gov (United States)

    Markus, Wiebren; de Weert-van Oene, Gerdien H; Woud, Marcella L; Becker, Eni S; DeJong, Cornelis A J

    2016-09-01

    Experimental research suggests that working memory (WM) taxation reduces craving momentarily. Using a modified Eye Movement Desensitization and Reprocessing (EMDR) procedure, prolonged reductions in craving and relapse rates in alcohol dependence have been demonstrated. Modified EMDR-procedures may also hold promise in smoking cessation attempts. A proof-of-concept study was conducted to narrow the gap between WM-taxation experiments and clinical EMDR studies. To this end the clinical EMDR-procedure was modified for use in a laboratory experiment. Daily smokers (n = 47), abstaining overnight, were allocated (by minimization randomization) to one of two groups using a parallel design. In both cases a modified EMDR-procedure was used. In the experimental group (n = 24) eye movements (EM) were induced while control group participants (n = 23) fixed their gaze (not taxing WM). During 6 min trials, craving-inducing memories were recalled. Craving, vividness of target memories, and smoking behavior were assessed at several variable-specific time-points between baseline (one week pre-intervention) and one week follow-up. The experimental group showed significant immediate reductions of craving and vividness of targeted memories. However, these effects were lost during a one-week follow-up period. A limited dose of WM-taxation, in the form of EM in a modified EMDR-procedure, resulted in transient effects on memory vividness and nicotine craving. EM provide a valuable way of coping with the acute effects of craving during smoking cessation attempts. Other aspects of the EMDR-procedure may provide additional effects. Component and dose-response studies are needed to establish the potential of EMDR-therapy in smoking cessation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. A benchmark on the calculation of kinetic parameters based on reactivity effect experiments in the CROCUS reactor

    International Nuclear Information System (INIS)

    Paratte, J.M.; Frueh, R.; Kasemeyer, U.; Kalugin, M.A.; Timm, W.; Chawla, R.

    2006-01-01

    Measurements in the CROCUS reactor at EPFL, Lausanne, are reported for the critical water level and the inverse reactor period for several different sets of delayed supercritical conditions. The experimental configurations were also calculated by four different calculation methods. For each of the supercritical configurations, the absolute reactivity value has been determined in two different ways, viz.: (i) through direct comparison of the multiplication factor obtained employing a given calculation method with the corresponding value for the critical case (calculated reactivity: ρ calc ); (ii) by application of the inhour equation using the kinetic parameters obtained for the critical configuration and the measured inverse reactor period (measured reactivity: ρ meas ). The calculated multiplication factors for the reference critical configuration, as well as ρ calc for the supercritical cases, are found to be in good agreement. However, the values of ρ meas produced by two of the applied calculation methods differ appreciably from the corresponding ρ calc values, clearly indicating deficiencies in the kinetic parameters obtained from these methods

  18. Transient pseudohypoaldosteronism

    Directory of Open Access Journals (Sweden)

    Stajić Nataša

    2011-01-01

    Full Text Available Introduction. Infants with urinary tract malformations (UTM presenting with urinary tract infection (UTI are prone to develop transient type 1 pseudohypoaldosteronism (THPA1. Objective. Report on patient series with characteristics of THPA1, UTM and/or UTI and suggestions for the diagnosis and therapy. Methods. Patients underwent blood and urine electrolyte and acid-base analysis, serum aldosterosterone levels and plasma rennin activity measuring; urinalysis, urinoculture and renal ultrasound were done and medical and/or surgical therapy was instituted. Results. Hyponatraemia (120.9±5.8 mmol/L, hyperkalaemia (6.9±0.9 mmol/L, metabolic acidosis (plasma bicarbonate, 11±1.4 mmol/L, and a rise in serum creatinine levels (145±101 μmol/L were associated with inappropriately high urinary sodium (51.3±17.5 mmol/L and low potassium (14.1±5.9 mmol/L excretion. Elevated plasma aldosterone concentrations (170.4±100.5 ng/dL and the very high levels of the plasma aldosterone to potassium ratio (25.2±15.6 together with diminished urinary K/Na values (0.31±0.19 indicated tubular resistance to aldosterone. After institution of appropriate medical and/or surgical therapy, serum electrolytes, creatinine, and acid-base balance were normalized. Imaging studies showed ureteropyelic or ureterovesical junction obstruction in 3 and 2 patients, respectively, posterior urethral valves in 3, and normal UT in 1 patient. According to our knowledge, this is the first report on THPA1 in the Serbian literature. Conclusion. Male infants with hyponatraemia, hyperkalaemia and metabolic acidosis have to have their urine examined and the renal ultrasound has to be done in order to avoid both, the underdiagnosis of THPA1 and the inappropriate medication.

  19. Data report of ROSA/LSTF experiment TR-LF-07. Loss-of-feedwater transient with primary feed-and-bleed operation

    International Nuclear Information System (INIS)

    Takeda, Takeshi

    2016-07-01

    An experiment TR-LF-07 was conducted on June 23, 1992 using the Large Scale Test Facility (LSTF) in the Rig of Safety Assessment-IV (ROSA-IV) Program. The ROSA/LSTF experiment TR-LF-07 simulated a loss-of-feedwater transient in a pressurized water reactor (PWR) under assumptions of primary feed-and-bleed operation and total failure of auxiliary feedwater system. A safety injection (SI) signal was generated when steam generator (SG) secondary-side collapsed liquid level decreased to 3 m. Primary depressurization was initiated by fully opening a power-operated relief valve (PORV) of pressurizer (PZR) 30 min after the SI signal. High pressure injection (HPI) system was started in loop with PZR 12 s after the SI signal, while it was initiated in loop without PZR when the primary pressure decreased to 10.7 MPa. The primary and SG secondary pressures were kept almost constant because of cycle opening of the PZR PORV and SG relief valves. The PZR liquid level began to drop steeply following the PORV full opening, which caused liquid level formation at the hot leg. The PZR and hot leg liquid levels recovered due to the HPI actuation in both loops. The primary pressure became lower than the SG secondary pressure, which resulted in the actuation of accumulator (ACC) system in both loops. The PZR and hot legs became full of liquid again after the ACC actuation. The primary feed-and-bleed operation by use of the PORV, HPI and ACC systems was effective to core cooling because of no core uncovery. The experiment was terminated when the continuous core cooling was confirmed due to the successive coolant injection from the HPI system even after the ACC termination. The obtained data would be useful to study operator actions and procedures in the PWR multiple fault events which behaviors in the PZR affect. This report summarizes the test procedures, conditions and major observation in the ROSA/LSTF experiment TR-LF-07. (author)

  20. Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach

    Energy Technology Data Exchange (ETDEWEB)

    Laureau, A., E-mail: laureau.axel@gmail.com; Heuer, D.; Merle-Lucotte, E.; Rubiolo, P.R.; Allibert, M.; Aufiero, M.

    2017-05-15

    Highlights: • Neutronic ‘Transient Fission Matrix’ approach coupled to the CFD OpenFOAM code. • Fission Matrix interpolation model for fast spectrum homogeneous reactors. • Application for coupled calculations of the Molten Salt Fast Reactor. • Load following, over-cooling and reactivity insertion transient studies. • Validation of the reactor intrinsic stability for normal and accidental transients. - Abstract: In this paper we present transient studies of the Molten Salt Fast Reactor (MSFR). This generation IV reactor is characterized by a liquid fuel circulating in the core cavity, requiring specific simulation tools. An innovative neutronic approach called “Transient Fission Matrix” is used to perform spatial kinetic calculations with a reduced computational cost through a pre-calculation of the Monte Carlo spatial and temporal response of the system. Coupled to this neutronic approach, the Computational Fluid Dynamics code OpenFOAM is used to model the complex flow pattern in the core. An accurate interpolation model developed to take into account the thermal hydraulics feedback on the neutronics including reactivity and neutron flux variation is presented. Finally different transient studies of the reactor in normal and accidental operating conditions are detailed such as reactivity insertion and load following capacities. The results of these studies illustrate the excellent behavior of the MSFR during such transients.

  1. Transient coupled calculations of the Molten Salt Fast Reactor using the Transient Fission Matrix approach

    International Nuclear Information System (INIS)

    Laureau, A.; Heuer, D.; Merle-Lucotte, E.; Rubiolo, P.R.; Allibert, M.; Aufiero, M.

    2017-01-01

    Highlights: • Neutronic ‘Transient Fission Matrix’ approach coupled to the CFD OpenFOAM code. • Fission Matrix interpolation model for fast spectrum homogeneous reactors. • Application for coupled calculations of the Molten Salt Fast Reactor. • Load following, over-cooling and reactivity insertion transient studies. • Validation of the reactor intrinsic stability for normal and accidental transients. - Abstract: In this paper we present transient studies of the Molten Salt Fast Reactor (MSFR). This generation IV reactor is characterized by a liquid fuel circulating in the core cavity, requiring specific simulation tools. An innovative neutronic approach called “Transient Fission Matrix” is used to perform spatial kinetic calculations with a reduced computational cost through a pre-calculation of the Monte Carlo spatial and temporal response of the system. Coupled to this neutronic approach, the Computational Fluid Dynamics code OpenFOAM is used to model the complex flow pattern in the core. An accurate interpolation model developed to take into account the thermal hydraulics feedback on the neutronics including reactivity and neutron flux variation is presented. Finally different transient studies of the reactor in normal and accidental operating conditions are detailed such as reactivity insertion and load following capacities. The results of these studies illustrate the excellent behavior of the MSFR during such transients.

  2. Track 5: safety in engineering, construction, operations, and maintenance. Reactor physics design, validation, and operating experience. 5. A Negative Reactivity Feedback Device for Actinide Burner Cores

    International Nuclear Information System (INIS)

    Driscoll, M.J.; Hejzlar, P.

    2001-01-01

    . Various other self-actuating reactivity devices have been investigated in the past, but more as safety shutdown features than for continuous feedback, for example, 1. the gas expansion module tested in the Fast Flux Test Facility (FFTF), in which core pressure drop compresses a gas bubble into the upper region of a vertical in-core through-tube. In a loss-of-flow (LOF) incident, the bubble expands to void the tube and remove reactivity by increasing leakage. 2. a fluidized bed of tantalum neutron poison balls, held out of core by coolant flow, which drops into a channel through the core during an LOF sequence; 3. a magnetic latch that exceeds its curie point in the temperature rise following a transient overpower event, and thereby allows a control absorber to fall into the core. The RFD is not a substitute for such other devices, nor does it avoid the need for conventional electro-mechanically driven control rods for regulation and shutdown. In fact, the latter will have to be enhanced to compensate for the automatic RFD withdrawal following scram. In summary, an RFD has been designed to compensate for some of the reactivity feedback shortcomings of actinide burner reactors. In principle, similar devices could also be used in other reactor types. (authors)

  3. Physics experiments with the operating reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cullington, G R; King, D C

    1973-09-27

    Experimental techniques have been developed and used on Dragon to give consistent information on excess reactivity and shut down margin. The reactivity measurements have been correlated with the theoretical calculations and have led to improvements in the calculations. The methods used and the results obtained are accepted by the Safety Committee as sufficient evidence for compliance with the fuel loading safety rules. Although the reactor was not designed as an experimental facility, flux and dose measurements experiments have been successfully carried out. Mass flow and negative reactivity transient measurements have been carried out. These are valuable for demonstration of the flexibility of the reactor system and for giving confidence in theoretical calculations.

  4. Transient or permanent fisheye views

    DEFF Research Database (Denmark)

    Jakobsen, Mikkel Rønne; Hornbæk, Kasper

    2012-01-01

    Transient use of information visualization may support specific tasks without permanently changing the user interface. Transient visualizations provide immediate and transient use of information visualization close to and in the context of the user’s focus of attention. Little is known, however......, about the benefits and limitations of transient visualizations. We describe an experiment that compares the usability of a fisheye view that participants could call up temporarily, a permanent fisheye view, and a linear view: all interfaces gave access to source code in the editor of a widespread...... programming environment. Fourteen participants performed varied tasks involving navigation and understanding of source code. Participants used the three interfaces for between four and six hours in all. Time and accuracy measures were inconclusive, but subjective data showed a preference for the permanent...

  5. Using Novel Laboratory Incubations and Field Experiments to Identify the Source and Fate of Reactive Organic Carbon in an Arsenic-contaminated Aquifer System

    Science.gov (United States)

    Stahl, M.; Tarek, M. H.; Badruzzaman, B.; Harvey, C. F.

    2017-12-01

    Characterizing the sources and fate of organic matter (OM) within aquifer systems is key to our understanding of both the broader global carbon cycle as well as the quality of our groundwater resources. The linkage between the subsurface carbon cycle and groundwater quality is perhaps nowhere more apparent than in the aquifer systems of South and Southeast Asia, where the contamination of groundwater with geogenic arsenic (As) is widespread and threatens the health of millions of individuals. OM fuels the biogeochemical processes driving As mobilization within these aquifers, however the source (i.e., modern surface-derived or aged sedimentary OM) of the reactive OM is widely debated. To characterize the sources of OM driving aquifer redox processes we tracked DIC and DOC concentrations and isotopes (stable and radiocarbon) along groundwater flow-paths and beneath an instrumented study pond at a field site in Bangladesh. We also conducted a set of novel groundwater incubation experiments, where we carbon-dated the DOC at the start and end of a experiment in order to determine the age of the OM that was mineralized. Our carbon/isotope balance reveals that aquifer recharge introduces a large quantity of young (i.e. near modern) OM that is efficiently mineralized within the upper few meters of the aquifer, effectively limiting this pool of reactive surface-sourced OM from being transported deeper into the aquifer where significant As mobilization takes place. The OM mineralized past the upper few meters is an aged, sedimentary source. Consistent with our field data, our incubation experiments show that past the upper few meters of the aquifer the reactive DOC is significantly older than the bulk DOC and has an age consistent with sedimentary OM. Combining our novel set of incubation experiments and a carbon/isotope balance along groundwater flow-paths and beneath our study pond we have identified the sources of reactive OM across different aquifer depths in a

  6. Sequential study on reactive blue 29 dye removal from aqueous solution by peroxy acid and single wall carbon nanotubes: experiment and theory

    Directory of Open Access Journals (Sweden)

    Jahangiri-Rad Mahsa

    2013-01-01

    Full Text Available Abstract The majority of anthraquinone dye released to the environment come from antrapogenic sources. Several techniques are available for dyes' removal. In this study removal of reactive blue 29 (RB29 by an advanced oxidation process sequenced with single wall carbon nanotubes was investigated. Advanced oxidation process was optimized over a period of 60 minutes by changing the ratio of acetic acid to hydrogen peroxide, the compounds which form peroxy acid. Reduction of 20.2% -56.4% of reactive blue 29 was observed when the ratio of hydrogen peroxide/acetic acid/dye changed from 344/344/1 to 344/344/0.08 at different times (60, 120 and 180 min. The optimum ratio of acetic acid/hydrogen peroxide/dye was found to be 344/344/0.16 over 60 min. The resultant then was introduced for further removal by single wall carbon nanotubes(SWCNTs as adsorbent. The adsorption of reactive blue 29 onto SWCNTs was also investigated. Langmuir, Freundlich and BET isotherms were determined and the results revealed that the adsorption of RB29 onto SWCNTs was well explained by BET model and changed to Freundlich isotherm when SWCNTs was used after the application of peroxy acid. Kinetic study showed that the equilibrium time for adsorption of RB 29 on to SWCNT is 4 h. Experiments were carried out to investigate adsorption kinetics, adsorbent capacity and the effect of solution pH on the removal of reactive blue29. The pseudo-second order kinetic equation could best describe the sorption kinetics. The most efficient pH for color removal (amongst pH=3, 5 and 8 was pH= 5. Further studies are needed to identify the peroxy acid degradation intermediates and to investigate their effects on SWCNTs.

  7. Experimental study on transient boiling heat transfer

    International Nuclear Information System (INIS)

    Visentini, R.

    2012-01-01

    Boiling phenomena can be found in the everyday life, thus a lot of studies are devoted to them, especially in steady state conditions. Transient boiling is less known but still interesting as it is involved in the nuclear safety prevention. In this context, the present work was supported by the French Institute of Nuclear Safety (IRSN). In fact, the IRSN wanted to clarify what happens during a Reactivity-initiated Accident (RIA). This accident occurs when the bars that control the nuclear reactions break down and a high power peak is passed from the nuclear fuel bar to the surrounding fluid. The temperature of the nuclear fuel bar wall increases and the fluid vaporises instantaneously. Previous studies on a fuel bar or on a metal tube heated by Joule effect were done in the past in order to understand the rapid boiling phenomena during a RIA. However, the measurements were not really accurate because the measurement techniques were not able to follow rapid phenomena. The main goal of this work was to create an experimental facility able to simulate the RIA boiling conditions but at small scale in order to better understand the boiling characteristics when the heated-wall temperature increases rapidly. Moreover, the experimental set-up was meant to be able to produce less-rapid transients as well, in order to give information on transient boiling in general. The facility was built at the Fluid-Mechanics Institute of Toulouse. The core consists of a metal half-cylinder heated by Joule effect, placed in a half-annulus section. The inner half cylinder is made of a 50 microns thick stainless steel foil. Its diameter is 8 mm, and its length 200 mm. The outer part is a 34 mm internal diameter glass half cylinder. The semi-annular section is filled with a coolant, named HFE7000. The configuration allows to work in similarity conditions. The heated part can be place inside a loop in order to study the flow effect. The fluid temperature influence is taken into account as

  8. Additional 5 kWe thermoelectric system temperature transients

    International Nuclear Information System (INIS)

    Halfen, F.J.

    1972-01-01

    Several additional system transients have been calculated for the 5 kW(e) TE system and are reported in this document. They include a startup transient with a reactivity rate of 0.005 cents/sec, several startup accidents, a step reactivity insertion at full power and a loss of electrical load. These data are intended for input to system design analyses and for possible use in the protected accident section of the safety report. (U.S.)

  9. Sensitivity analysis for reactivity parameter change of the creole experiment caused by the differences between ENDF-BVII and JENDL neutron cross section evaluations

    International Nuclear Information System (INIS)

    Boulaich, Y.; Bardouni, C.; Elyounoussi, C.; Elbakkari, H.; Boukhal, H.; Erradi, L.; Nacir, B.

    2011-01-01

    Full text: In this work, we present our analysis of the CREOLE experiment on the parameter by using the three-dimensional continuous energy code (MCNPS) and the last updated nuclear data evaluations. This experiment performed in the EOLE critical facility located at CEA-Cadarache, was dedicated to studies for both UO2 and UO2-PuO2 PWR type lattices covering the whole temperature range from 20 0 C to 300 0 C. We have developed an accurate model of the EOLE reactor to be used by the MCNP5 Monte Carlo code. This model guarantees a high level of fidelity in the description of different configurations at various temperatures taking into account their consequence on neutron cross section data and all thermal expansion effects. In this case, the remaining error between calculation and experiment will be awarded mainly to uncertainties on nuclear data. Our own cross section library was constructed by using NJOY99.259 code with point-wise nuclear data based on ENDF-BVII. JEFF3.1, JENDL3.3 and JENDL4 evaluation files. The MCNP model was validated through the axial and radial fission rate measurements at room and hot temperatures. Calculation-experiment discrepancies of the reactivity parameter were analyzed and the results have shown that the JENDL evaluations give the most consistent values. In order to specify the source of the relatively large difference between experiment and calculation due to ENDF-BVII nuclear data evaluation, the discrepancy in reactivity between ENDF-BVII and JENDL evaluations was decomposed using sensitivity and uncertainty analysis technique

  10. Using laboratory flow experiments and reactive chemical transport modeling for designing waterflooding of the Agua Fria Reservoir, Poza Rica-Altamira Field, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Birkle, P.; Pruess, K.; Xu, T.; Figueroa, R.A. Hernandez; Lopez, M. Diaz; Lopez, E. Contreras

    2008-10-01

    Waterflooding for enhanced oil recovery requires that injected waters must be chemically compatible with connate reservoir waters, in order to avoid mineral dissolution-and-precipitation cycles that could seriously degrade formation permeability and injectivity. Formation plugging is a concern especially in reservoirs with a large content of carbonates, such as calcite and dolomite, as such minerals typically react rapidly with an aqueous phase, and have strongly temperature-dependent solubility. Clay swelling can also pose problems. During a preliminary waterflooding pilot project, the Poza Rica-Altamira oil field, bordering the Gulf coast in the eastern part of Mexico, experienced injectivity loss after five months of reinjection of formation waters into well AF-847 in 1999. Acidizing with HCl restored injectivity. We report on laboratory experiments and reactive chemistry modeling studies that were undertaken in preparation for long-term waterflooding at Agua Frma. Using analogous core plugs obtained from the same reservoir interval, laboratory coreflood experiments were conducted to examine sensitivity of mineral dissolution and precipitation effects to water composition. Native reservoir water, chemically altered waters, and distilled water were used, and temporal changes in core permeability, mineral abundances and aqueous concentrations of solutes were monitored. The experiments were simulated with the multi-phase, nonisothermal reactive transport code TOUGHREACT, and reasonable to good agreement was obtained for changes in solute concentrations. Clay swelling caused an additional impact on permeability behavior during coreflood experiments, whereas the modeled permeability depends exclusively on chemical processes. TOUGHREACT was then used for reservoir-scale simulation of injecting ambient-temperature water (30 C, 86 F) into a reservoir with initial temperature of 80 C (176 F). Untreated native reservoir water was found to cause serious porosity and

  11. Development of a standard data base for FBR core nuclear design (XIII). Analysis of small sample reactivity experiments at ZPPR-9

    International Nuclear Information System (INIS)

    Sato, Wakaei; Fukushima, Manabu; Ishikawa, Makoto

    2000-09-01

    A comprehensive study to evaluate and accumulate the abundant results of fast reactor physics is now in progress at O-arai Engineering Center to improve analytical methods and prediction accuracy of nuclear design for large fast breeder cores such as future commercial FBRs. The present report summarizes the analytical results of sample reactivity experiments at ZPPR-9 core, which has not been evaluated by the latest analytical method yet. The intention of the work is to extend and further generalize the standard data base for FBR core nuclear design. The analytical results of the sample reactivity experiments (samples: PU-30, U-6, DU-6, SS-1 and B-1) at ZPPR-9 core in JUPITER series, with the latest nuclear data library JENDL-3.2 and the analytical method which was established by the JUPITER analysis, can be concluded as follows: The region-averaged final C/E values generally agreed with unity within 5% differences at the inner core region. However, the C/E values of every sample showed the radial space-dependency increasing from center to core edge, especially the discrepancy of B-1 was the largest by 10%. Next, the influence of the present analytical results for the ZPPR-9 sample reactivity to the cross-section adjustment was evaluated. The reference case was a unified cross-section set ADJ98 based on the recent JUPITER analysis. As a conclusion, the present analytical results have sufficient physical consistency with other JUPITER data, and possess qualification as a part of the standard data base for FBR nuclear design. (author)

  12. Engineering of the chemical reactivity of the Ti/HfO₂ interface for RRAM: experiment and theory.

    Science.gov (United States)

    Calka, Pauline; Sowinska, Malgorzata; Bertaud, Thomas; Walczyk, Damian; Dabrowski, Jarek; Zaumseil, Peter; Walczyk, Christian; Gloskovskii, Andrei; Cartoixà, Xavier; Suñé, Jordi; Schroeder, Thomas

    2014-04-09

    The Ti/HfO2 interface plays a major role for resistance switching performances. However, clear interface engineering strategies to achieve reliable and reproducible switching have been poorly investigated. For this purpose, we present a comprehensive study of the Ti/HfO2 interface by a combined experimental-theoretical approach. Based on the use of oxygen-isotope marked Hf*O2, the oxygen scavenging capability of the Ti layer is clearly proven. More importantly, in line with ab initio theory, the combined HAXPES-Tof-SIMS study of the thin films deposited by MBE clearly establishes a strong impact of the HfO2 thin film morphology on the Ti/HfO2 interface reactivity. Low-temperature deposition is thus seen as a RRAM processing compatible way to establish the critical amount of oxygen vacancies to achieve reproducible and reliable resistance switching performances.

  13. Enteral Feeding During Chemoradiotherapy for Advanced Head-and-Neck Cancer: A Single-Institution Experience Using a Reactive Approach

    International Nuclear Information System (INIS)

    Clavel, Sebastien; Fortin, Bernard; Despres, Philippe; Donath, David; Soulieres, Denis; Khaouam, Nader; Charpentier, Danielle; Belair, Manon; Guertin, Louis; Nguyen-Tan, Phuc Felix

    2011-01-01

    Purpose: The optimal method for providing enteral nutrition to patients with head-and-neck cancer is unclear. The purpose of the present study was to evaluate the safety and efficacy of our reactive policy, which consists of the installation of a nasogastric (NG) feeding tube only when required by the patient's nutritional status. Methods and Materials: The records of all patients with Stage III and IV head-and-neck cancer treated with concomitant chemotherapy and radiotherapy between January 2003 and December 2006 were reviewed. The overall and disease-free survival rates were estimated using the Kaplan-Meier method and compared with the log-rank test. Results: The present study included 253 patients, and the median follow-up was 33 months. At 3 years, the estimated overall survival and disease-free survival rate was 82.8% and 77.8%, respectively, for the whole population. No survival difference was observed when the patients were compared according to the presence and absence of a NG tube or stratified by weight loss quartile. The mean weight loss during treatment for all patients was 10.4%. The proportion of patients requiring a NG tube was 49.8%, and the NG tube remained in place for a median duration of 40 days. No major complications were associated with NG tube installation. Only 3% of the patients were still dependent on enteral feeding at 6 months. Conclusion: These results suggest that the use of a reactive NG tube with an interdisciplinary team approach is a safe and effective method to manage malnutrition in patients treated with concomitant chemotherapy and radiotherapy for head-and-neck cancer.

  14. Current interruption transients calculation

    CERN Document Server

    Peelo, David F

    2014-01-01

    Provides an original, detailed and practical description of current interruption transients, origins, and the circuits involved, and how they can be calculated Current Interruption Transients Calculationis a comprehensive resource for the understanding, calculation and analysis of the transient recovery voltages (TRVs) and related re-ignition or re-striking transients associated with fault current interruption and the switching of inductive and capacitive load currents in circuits. This book provides an original, detailed and practical description of current interruption transients, origins,

  15. HEDL experimental transient overpower program

    International Nuclear Information System (INIS)

    Hikido, T.; Culley, G.E.

    1976-01-01

    HEDL is conducting a series of experiments to evaluate the performance of Fast Flux Test Facility (FFTF) prototypic fuel pins up to the point of cladding breach. A primary objective of the program is to demonstrate the adequacy of fuel pin and Plant Protective System (PPS) designs for terminated transients. Transient tests of prototypic FFTF fuel pins previously irradiated in the Experimental Breeder Reactor-II (EBR-II) have demonstrated the adequacy of the PPS and fuel pin designs and indicate that a very substantial margin exists between PPS-terminated transients and that required to produce fuel pin cladding failure. Additional experiments are planned to extend the data base to high burnup, high fluence fuel pin specimens

  16. Future Transient Testing of Advanced Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Jon Carmack

    2009-09-01

    the refurbishment and restart of TREAT. •TREAT is an absolute necessity in the suite of reactor fuel test capabilities •TREAT yields valuable information on reactivity effects, margins to failure, fuel dispersal, and failure propagation •Most importantly, interpretation of TREAT experiment results is a stringent test of the integrated understanding of fuel performance.

  17. Future Transient Testing of Advanced Fuels

    International Nuclear Information System (INIS)

    Carmack, Jon

    2009-01-01

    refurbishment and restart of TREAT: (1) TREAT is an absolute necessity in the suite of reactor fuel test capabilities; (2) TREAT yields valuable information on reactivity effects, margins to failure, fuel dispersal, and failure propagation; and (3) Most importantly, interpretation of TREAT experiment results is a stringent test of the integrated understanding of fuel performance.

  18. Narcisismo reativo e experiência religiosa contemporânea: culpa substituída pela vergonha? Reactive narcissism and contemporary religious experience: a shift from guilt to shame?

    Directory of Open Access Journals (Sweden)

    Mary Rute Gomes Esperandio

    2007-08-01

    Full Text Available O texto apresenta um recorte da reflexão desenvolvida na tese de doutorado: "Narcisismo e sacrifício: Modo de subjetivação e religiosidade contemporânea" (Esperandio, 2006. Trata-se de uma análise da experiência religiosa promovida pela Igreja Universal do Reino de Deus (IURD a partir da sua proposta de sacrifício. A abordagem trabalha com a concepção de narcisismo ativo e reativo e defende a idéia de que a prática do sacrifício, tal como proposta pela IURD, articula elementos do narcisismo reativo e estabelece-se como uma tecnologia do eu, usada como remédio para lidar com a experiência contemporânea da vergonha.This text presents part of the reflection developed in my Doctoral Thesis on "Narcissism and sacrifice: Mode of subjectivation and contemporary religiosity" (Esperandio, 2006. It analyses the religious experience supported by the Universal Church of the Kingdom of God (UCKG on its proposal of sacrifice. This approach sustains the conception of active and reactive narcissism and defends the idea that such practice of sacrifice proposed by UCKG relates some elements of reactive narcissism and establishes itself as a Technology of Self used as a remedy to deal with the contemporary experience of shame.

  19. Design criteria of integrated reactors based on transients

    International Nuclear Information System (INIS)

    Zanocco, P.; Gimenez, M.; Delmastro, D.

    1999-01-01

    A new tendency in integrated reactors conceptual design is to include safety criteria through accident analysis. In this work, the effect of design parameters in a Loss of Heat Sink transient using design maps is analyzed. Particularly, geometry related parameters and reactivity coefficients are studied. Also the effect of primary relief/safety valve during the transient is evaluated. A design map for valve area vs. coolant density reactivity coefficient is obtained. A computer code (HUARPE) is developed in order to simulate these transients. Coolant, steam dome, pressure vessel structures and core models are implemented. This code is checked against TRAC with satisfactory results. (author)

  20. Analysis of metallic fuel pin behaviors under transient conditions of liquid metal reactors

    International Nuclear Information System (INIS)

    Nam, Cheol; Kwon, Hyoung Mun; Hwang, Woan

    1999-02-01

    Transient behavior of metallic fuel pins in liquid metal reactor is quite different to that in steady state conditions. Even in transient conditions, the fuel may behave differently depending on its accident situation and/or accident sequence. This report describes and identifies the possible and hypothetical transient events at the aspects of fuel pin behavior. Furthermore, the transient experiments on HT9 clad metallic fuel have been analyzed, and then failure assessments are performed based on accident classes. As a result, the failure mechanism of coolant-related accidents, such as LOF, is mainly due to plenum pressure and cladding thinning caused by eutectic penetration. In the reactivity-related accidents, such as TOP, the reason to cladding failure is believed to be the fuel swelling as well as plenum pressure. The probabilistic Weibull analysis is performed to evaluate the failure behavior of HT9 clad-metallic fuel pin on coolant related accidents.The Weibull failure function is derived as a function of cladding CDF. Using the function, a sample calculation for the ULOF accident of EBR-II fuel is performed, and the results indicate that failure probability is less the 0.3%. Further discussion on failure criteria of accident condition is provided. Finally, it is introduced the state-of-arts for developing computer codes of reactivity-related fuel pin behavior. The development efforts for a simple model to predict transient fuel swelling is described, and the preliminary calculation results compared to hot pressing test results in literature.This model is currently under development, and it is recommended in the future that the transient swelling model will be combined with the cladding model and the additional development for post-failure behavior of fuel pin is required. (Author). 36 refs., 9 tabs., 18 figs

  1. Sensitivity analysis of reactive ecological dynamics.

    Science.gov (United States)

    Verdy, Ariane; Caswell, Hal

    2008-08-01

    Ecological systems with asymptotically stable equilibria may exhibit significant transient dynamics following perturbations. In some cases, these transient dynamics include the possibility of excursions away from the equilibrium before the eventual return; systems that exhibit such amplification of perturbations are called reactive. Reactivity is a common property of ecological systems, and the amplification can be large and long-lasting. The transient response of a reactive ecosystem depends on the parameters of the underlying model. To investigate this dependence, we develop sensitivity analyses for indices of transient dynamics (reactivity, the amplification envelope, and the optimal perturbation) in both continuous- and discrete-time models written in matrix form. The sensitivity calculations require expressions, some of them new, for the derivatives of equilibria, eigenvalues, singular values, and singular vectors, obtained using matrix calculus. Sensitivity analysis provides a quantitative framework for investigating the mechanisms leading to transient growth. We apply the methodology to a predator-prey model and a size-structured food web model. The results suggest predator-driven and prey-driven mechanisms for transient amplification resulting from multispecies interactions.

  2. Reactive Arthritis

    Directory of Open Access Journals (Sweden)

    Eren Erken

    2013-06-01

    Full Text Available Reactive arthritis is an acute, sterile, non-suppurative and inflammatory arthropaty which has occured as a result of an infectious processes, mostly after gastrointestinal and genitourinary tract infections. Reiter syndrome is a frequent type of reactive arthritis. Both reactive arthritis and Reiter syndrome belong to the group of seronegative spondyloarthropathies, associated with HLA-B27 positivity and characterized by ongoing inflammation after an infectious episode. The classical triad of Reiter syndrome is defined as arthritis, conjuctivitis and urethritis and is seen only in one third of patients with Reiter syndrome. Recently, seronegative asymmetric arthritis and typical extraarticular involvement are thought to be adequate for the diagnosis. However, there is no established criteria for the diagnosis of reactive arthritis and the number of randomized and controlled studies about the therapy is not enough. [Archives Medical Review Journal 2013; 22(3.000: 283-299

  3. Reactive scattering of H2 from Cu(100): comparison of dynamics calculations based on the specific reaction parameter approach to density functional theory with experiment.

    Science.gov (United States)

    Sementa, L; Wijzenbroek, M; van Kolck, B J; Somers, M F; Al-Halabi, A; Busnengo, H F; Olsen, R A; Kroes, G J; Rutkowski, M; Thewes, C; Kleimeier, N F; Zacharias, H

    2013-01-28

    We present new experimental and theoretical results for reactive scattering of dihydrogen from Cu(100). In the new experiments, the associative desorption of H(2) is studied in a velocity resolved and final rovibrational state selected manner, using time-of-flight techniques in combination with resonance-enhanced multi-photon ionization laser detection. Average desorption energies and rotational quadrupole alignment parameters were obtained in this way for a number of (v = 0, 1) rotational states, v being the vibrational quantum number. Results of quantum dynamics calculations based on a potential energy surface computed with a specific reaction parameter (SRP) density functional, which was derived earlier for dihydrogen interacting with Cu(111), are compared with the results of the new experiments and with the results of previous molecular beam experiments on sticking of H(2) and on rovibrationally elastic and inelastic scattering of H(2) and D(2) from Cu(100). The calculations use the Born-Oppenheimer and static surface approximations. With the functional derived semi-empirically for dihydrogen + Cu(111), a chemically accurate description is obtained of the molecular beam experiments on sticking of H(2) on Cu(100), and a highly accurate description is obtained of rovibrationally elastic and inelastic scattering of D(2) from Cu(100) and of the orientational dependence of the reaction of (v = 1, j = 2 - 4) H(2) on Cu(100). This suggests that a SRP density functional derived for H(2) interacting with a specific low index face of a metal will yield accurate results for H(2) reactively scattering from another low index face of the same metal, and that it may also yield accurate results for H(2) interacting with a defected (e.g., stepped) surface of that same metal, in a system of catalytic interest. However, the description that was obtained of the average desorption energies, of rovibrationally elastic and inelastic scattering of H(2) from Cu(100), and of the

  4. Transient drainage summary report

    International Nuclear Information System (INIS)

    1996-09-01

    This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage

  5. PSH Transient Simulation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-12-21

    PSH Transient Simulation Modeling presentation from the WPTO FY14 - FY16 Peer Review. Transient effects are an important consideration when designing a PSH system, yet numerical techniques for hydraulic transient analysis still need improvements for adjustable-speed (AS) reversible pump-turbine applications.

  6. Structure and reactivity of oxalate surface complexes on lepidocrocite derived from infrared spectroscopy, DFT-calculations, adsorption, dissolution and photochemical experiments

    Science.gov (United States)

    Borowski, Susan C.; Biswakarma, Jagannath; Kang, Kyounglim; Schenkeveld, Walter D. C.; Hering, Janet G.; Kubicki, James D.; Kraemer, Stephan M.; Hug, Stephan J.

    2018-04-01

    Oxalate, together with other ligands, plays an important role in the dissolution of iron(hdyr)oxides and the bio-availability of iron. The formation and properties of oxalate surface complexes on lepidocrocite were studied with a combination of infrared spectroscopy (IR), density functional theory (DFT) calculations, dissolution, and photochemical experiments. IR spectra measured as a function of time, concentration, and pH (50-200 μM oxalate, pH 3-7) showed that several surface complexes are formed at different rates and in different proportions. Measured spectra could be separated into three contributions described by Gaussian line shapes, with frequencies that agreed well with the theoretical frequencies of three different surface complexes: an outer-sphere complex (OS), an inner-sphere monodentate mononuclear complex (MM), and a bidentate mononuclear complex (BM) involving one O atom from each carboxylate group. At pH 6, OS was formed at the highest rate. The contribution of BM increased with decreasing pH. In dissolution experiments, lepidocrocite was dissolved at rates proportional to the surface concentration of BM, rather than to the total adsorbed concentration. Under UV-light (365 nm), BM was photolyzed at a higher rate than MM and OS. Although the comparison of measured spectra with calculated frequencies cannot exclude additional possible structures, the combined results allowed the assignment of three main structures with different reactivities consistent with experiments. The results illustrate the importance of the surface speciation of adsorbed ligands in dissolution and photochemical reactions.

  7. Combining water-rock interaction experiments with reaction path and reactive transport modelling to predict reservoir rock evolution in an enhanced geothermal system

    Science.gov (United States)

    Kuesters, Tim; Mueller, Thomas; Renner, Joerg

    2016-04-01

    Reliably predicting the evolution of mechanical and chemical properties of reservoir rocks is crucial for efficient exploitation of enhanced geothermal systems (EGS). For example, dissolution and precipitation of individual rock forming minerals often result in significant volume changes, affecting the hydraulic rock properties and chemical composition of fluid and solid phases. Reactive transport models are typically used to evaluate and predict the effect of the internal feedback of these processes. However, a quantitative evaluation of chemo-mechanical interaction in polycrystalline environments is elusive due to poorly constrained kinetic data of complex mineral reactions. In addition, experimentally derived reaction rates are generally faster than reaction rates determined from natural systems, likely a consequence of the experimental design: a) determining the rate of a single process only, e.g. the dissolution of a mineral, and b) using powdered sample materials and thus providing an unrealistically high reaction surface and at the same time eliminating the restrictions on element transport faced in-situ for fairly dense rocks. In reality, multiple reactions are coupled during the alteration of a polymineralic rocks in the presence of a fluid and the rate determining process of the overall reactions is often difficult to identify. We present results of bulk rock-water interaction experiments quantifying alteration reactions between pure water and a granodiorite sample. The rock sample was chosen for its homogenous texture, small and uniform grain size (˜0.5 mm in diameter), and absence of pre-existing alteration features. The primary minerals are plagioclase (plg - 58 vol.%), quartz (qtz - 21 vol.%), K-feldspar (Kfs - 17 vol.%), biotite (bio - 3 vol.%) and white mica (wm - 1 vol.%). Three sets of batch experiments were conducted at 200 ° C to evaluate the effect of reactive surface area and different fluid path ways using (I) powders of the bulk rock with

  8. Reactivity costs in MARIA reactor

    International Nuclear Information System (INIS)

    Marcinkowska, Zuzanna E.; Pytel, Krzysztof M.; Frydrysiak, Andrzej

    2017-01-01

    Highlights: • The methodology for calculating consumed fuel cost of excess reactivity is proposed. • Correlation between time integral of the core excess reactivity and released energy. • Reactivity price gives number of fuel elements required for given excess reactivity. - Abstract: For the reactor operation at high power level and carrying out experiments and irradiations the major cost of reactor operation is the expense of nuclear fuel. In this paper the methodology for calculating consumed fuel cost-relatedness of excess reactivity is proposed. Reactivity costs have been determined on the basis of operating data. A number of examples of calculating the reactivity costs for processes such as: strong absorbing material irradiation, molybdenium-99 production, beryllium matrix poisoning and increased moderator temperature illustrates proposed method.

  9. Core Flooding Experiments and Reactive Transport Modeling of Seasonal Heat Storage in the Hot Deep Gassum Sandstone Formation

    DEFF Research Database (Denmark)

    Holmslykke, Hanne D.; Kjøller, Claus; Fabricius, Ida Lykke

    2017-01-01

    Seasonal storage of excess heat in hot deep aquifers is considered to optimize the usage of commonly available energy sources. The chemical effects of heating the Gassum Sandstone Formation to up to 150 degrees C is investigated by combining laboratory core flooding experiments with petrographic...... analysis and geochemical modeling. Synthetic formation water is injected into two sets of Gassum Formation samples at 25, 50 (reservoir temperature), 100, and 150 degrees C with a velocity of 0.05 and 0.1 PV/h, respectively. Results show a significant increase in the aqueous concentration of silicium...

  10. Development of a three dimensional homogeneous calculation model for the BFS-62 critical experiment. Preparation of adjusted equivalent measured values for sodium void reactivity values. Final report

    International Nuclear Information System (INIS)

    Manturov, G.; Semenov, M.; Seregin, A.; Lykova, L.

    2004-01-01

    The BFS-62 critical experiments are currently used as 'benchmark' for verification of IPPE codes and nuclear data, which have been used in the study of loading a significant amount of Pu in fast reactors. The BFS-62 experiments have been performed at BFS-2 critical facility of IPPE (Obninsk). The experimental program has been arranged in such a way that the effect of replacement of uranium dioxied blanket by the steel reflector as well as the effect of replacing UOX by MOX on the main characteristics of the reactor model was studied. Wide experimental program, including measurements of the criticality-keff, spectral indices, radial and axial fission rate distributions, control rod mock-up worth, sodium void reactivity effect SVRE and some other important nuclear physics parameters, was fulfilled in the core. Series of 4 BFS-62 critical assemblies have been designed for studying the changes in BN-600 reactor physics from existing state to hybrid core. All the assemblies are modeling the reactor state prior to refueling, i.e. with all control rod mock-ups withdrawn from the core. The following items are chosen for the analysis in this report: Description of the critical assembly BFS-62-3A as the 3rd assembly in a series of 4 BFS critical assemblies studying BN-600 reactor with MOX-UOX hybrid zone and steel reflector; Development of a 3D homogeneous calculation model for the BFS-62-3A critical experiment as the mock-up of BN-600 reactor with hybrid zone and steel reflector; Evaluation of measured nuclear physics parameters keff and SVRE (sodium void reactivity effect); Preparation of adjusted equivalent measured values for keff and SVRE. Main series of calculations are performed using 3D HEX-Z diffusion code TRIGEX in 26 groups, with the ABBN-93 cross-section set. In addition, precise calculations are made, in 299 groups and Ps-approximation in scattering, by Monte-Carlo code MMKKENO and discrete ordinate code TWODANT. All calculations are based on the common system

  11. Acoustic Transient Source Localization From an Aerostat

    National Research Council Canada - National Science Library

    Scanlon, Michael; Reiff, Christian; Noble, John

    2006-01-01

    The Army Research Laboratory (ARL) has conducted experiments using acoustic sensor arrays suspended below tethered aerostats to detect and localize transient signals from mortars, artillery and small arms fire...

  12. New developments in French transient monitoring: SYSFAC

    International Nuclear Information System (INIS)

    L'huby, Y.; Genette, P.; Faidy, C.; Kappler, F.; Balley, J.; Bimont, G.

    1991-01-01

    After more than ten years of experience with Transient Monitoring and Logging Procedure (TMLP) and six years of successfully experience with Fatiguemeters, EDF has decided to study a new concept of Fatigue Monitoring System: SYSFAC. This new automatic system which is developed to be operating in all the French PWR units is composed of three modules: mechanical transient logging, functional transient logging and fatiguemeters. This application must be connected to the on-site data acquisition system without complementary instrumentation on the plant. (author)

  13. Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration

    Directory of Open Access Journals (Sweden)

    H. Fuchs

    2012-07-01

    Full Text Available During recent field campaigns, hydroxyl radical (OH concentrations that were measured by laser-induced fluorescence (LIF were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jülich, Germany, in order to investigate the photochemical degradation of isoprene, methyl-vinyl ketone (MVK, methacrolein (MACR and aromatic compounds by OH. Conditions were similar to those experienced during the PRIDE-PRD2006 campaign in the Pearl River Delta (PRD, China, in 2006, where a large difference between OH measurements and model predictions was found. During experiments in SAPHIR, OH was simultaneously detected by two independent instruments: LIF and differential optical absorption spectroscopy (DOAS. Because DOAS is an inherently calibration-free technique, DOAS measurements are regarded as a reference standard. The comparison of the two techniques was used to investigate potential artifacts in the LIF measurements for PRD-like conditions of OH reactivities of 10 to 30 s−1 and NO mixing ratios of 0.1 to 0.3 ppbv. The analysis of twenty experiment days shows good agreement. The linear regression of the combined data set (averaged to the DOAS time resolution, 2495 data points yields a slope of 1.02 ± 0.01 with an intercept of (0.10 ± 0.03 × 106 cm−3 and a linear correlation coefficient of R2 = 0.86. This indicates that the sensitivity of the LIF instrument is well-defined by its calibration procedure. No hints for artifacts are observed for isoprene, MACR, and different aromatic compounds. LIF measurements were approximately 30–40% (median larger than those by DOAS after MVK (20 ppbv and

  14. Reactive transport of uranyl: fixation mode on silica and goethite; experiments in columns and closed reactors; simulations

    International Nuclear Information System (INIS)

    Gabriel, U.

    1998-01-01

    Uranium contaminated areas are found in mine waste disposal sites, former military areas, etc. The present study focuses on the identification or mechanisms which may lead contaminated soils to become a sudden potential threat to surface and ground waters. Mechanisms were studied on model material at two levels. On the molecular scale, the complexation of uranyl at trace metal concentrations was investigated with amorphous silica. Complexation is shown to occur via the formation of surface complexes, characterised by different time-resolved laser-induced luminescence spectra and life times and stoichiometry. On the macro-scale the transport behaviour of uranyl in a cristobalite-goethite-carbonate-uranyl system was investigated with laboratory column and batch experiments. Uranium mobility was found to be controlled by the interaction between physical transport and a reversible, rate-controlled, fixation reaction. Sorption was shown to be an ensemble of competing solution and surface complexation reactions, leading to an apparent non-linear (Langmuir-like) adsorption isotherm. Finally the impact of a sudden change in background geochemistry was studied. Conditions leading to a dramatic mobilization of uranium from mildly contaminated systems were experimentally identified. Maximal uranyl concentration are controlled by the total extractable uranyl in the system and limited by uranyl solubility. Evolution of the background geochemical conditions is thus an important part of contaminated sites risk assessment. (author)

  15. A novel deep reactive ion etched (DRIE) glass micro-model for two-phase flow experiments.

    Science.gov (United States)

    Karadimitriou, N K; Joekar-Niasar, V; Hassanizadeh, S M; Kleingeld, P J; Pyrak-Nolte, L J

    2012-09-21

    In the last few decades, micro-models have become popular experimental tools for two-phase flow studies. In this work, the design and fabrication of an innovative, elongated, glass-etched micro-model with dimensions of 5 × 35 mm(2) and constant depth of 43 microns is described. This is the first time that a micro-model with such depth and dimensions has been etched in glass by using a dry etching technique. The micro-model was visualized by a novel setup that allowed us to monitor and record the distribution of fluids throughout the length of the micro-model continuously. Quasi-static drainage experiments were conducted in order to obtain equilibrium data points that relate capillary pressure to phase saturation. By measuring the flow rate of water through the flow network for known pressure gradients, the intrinsic permeability of the micro-model's flow network was also calculated. The experimental results were used to calibrate a pore-network model and test its validity. Finally, we show that glass-etched micro-models can be valuable tools in single and/or multi-phase flow studies and their applications.

  16. Core Flooding Experiments and Reactive Transport Modeling of Seasonal Heat Storage in the Hot Deep Gassum Sandstone Formation

    DEFF Research Database (Denmark)

    Holmslykke, Hanne D.; Kjøller, Claus; Fabricius, Ida Lykke

    2017-01-01

    Seasonal storage of excess heat in hot deep aquifers is considered to optimize the usage of commonly available energy sources. The chemical effects of heating the Gassum Sandstone Formation to up to 150 degrees C is investigated by combining laboratory core flooding experiments with petrographic ...... minor effects on the properties of the reservoir and that storage of excess heat in the Gassum Formation in the Stenlille area may be possible provided operational precautions are taken....... analysis and geochemical modeling. Synthetic formation water is injected into two sets of Gassum Formation samples at 25, 50 (reservoir temperature), 100, and 150 degrees C with a velocity of 0.05 and 0.1 PV/h, respectively. Results show a significant increase in the aqueous concentration of silicium...... and iron with increasing temperature due to dissolution of silica and siderite. Increasing the reservoir temperature from 50 to 100 degrees C enhanced the naturally occurring weathering of Na-rich feldspar to kaolinite. Dissolution of quartz increased sharply above 100 degrees C and was the dominating...

  17. Reduction of Mn-oxides by ferrous iron in a flow system: column experiment and reactive transport modeling

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Appelo, C. A. J.

    2000-01-01

    Cl2 solution into the column, an ion distribution pattern was observed in the effluent that suggests the formation of separate reaction fronts for Mn(III)-oxide and Mn(IV)-oxide travelling at different velocities through the column. At the proximal reaction front, Fe21 reacts with MnO2 producing Fe......The reduction of Mn-oxide by Fe21 was studied in column experiments, using a column filled with natural Mn-oxide coated sand. Analysis of the Mn-oxide indicated the presence of both Mn(III) and Mn(IV) in the Mn-oxide. The initial exchange capacity of the column was determined by displacement...... of adsorbed Ca21 with Mg21. Subsequently a FeCl2 solution was injected into the column causing the reduction of the Mn-oxide and the precipitation of Fe(OH)3. Finally the exchange capacity of the column containing newly formed Fe(OH)3 was determined by injection of a KBr solution. During injection of the Fe...

  18. Stress reactivity and its effects on subsequent food intake in depressed and healthy women with and without adverse childhood experiences.

    Science.gov (United States)

    Wingenfeld, Katja; Kuehl, Linn K; Boeker, Anita; Schultebraucks, Katharina; Ritter, Kristin; Hellmann-Regen, Julian; Otte, Christian; Spitzer, Carsten

    2017-06-01

    Adverse childhood experiences (ACE) increase the risk to develop major depressive disorder (MDD) and obesity or metabolic syndrome in adulthood. In addition, ACE may be associated with an exaggerated endocrine response to stress, which, in turn, may lead to enhanced food intake resulting in obesity and metabolic problems. We systematically examined the stress response and consecutive food intake in 32 women with MDD and ACE as determined by a clinical interview (Early Trauma Inventory), 52 women with MDD without ACE, 22 women with ACE but no current or lifetime MDD and 37 healthy women without either MDD or ACE. All participants underwent a psychosocial stress test (Trier Social Stress Test, TSST) and a control condition (Placebo-TSST) before they were offered a buffet of snacks. Participants were not aware that the primary outcome variable was the amount of consumed kilocalories (kcal). The four groups did not differ in demographic variables. Stress resulted in higher cortisol release and higher blood pressure compared to the control condition. Patients with MDD without ACE had a significantly lower cortisol response to stress compared to controls. Across groups, we found higher kcal intake after stress compared to the control condition. Comparing high and low cortisol responders to stress, higher kcal intake after stress was only seen in those with low cortisol release. This study provides evidence that blunted rather than enhanced cortisol release to stress might lead to increased food intake, independent from MDD and ACE. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Double Shock Experiments Performed at -55°C on LX-17 with Reactive Flow Modeling to Understand the Reacted Equation of State

    Science.gov (United States)

    Dehaven, Martin R.; Vandersall, Kevin S.; Strickland, Shawn L.; Fried, Laurence E.; Tarver, Craig M.

    2017-06-01

    Experiments were performed at -55°C to measure the reacted state of LX-17 (92.5% TATB and 7.5% Kel-F by weight) using a double shock technique using two flyer materials (with known properties) mounted on a projectile that send an initial shock through the material close to the Chapman-Jouguet (CJ) state followed by a second shock at a higher magnitude into the detonated material. Information on the reacted state is obtained by measuring the relative timing and magnitude of the first and second shock waves. The LX-17 detonation reaction zone profiles plus the arrival times and amplitudes of reflected shocks in LX-17 detonation reaction products were measured using Photonic Doppler Velocimetry (PDV) probes and an aluminum foil coated LiF window. A discussion of this work will include a comparison to prior work at ambient temperature, the experimental parameters, velocimetry profiles, data interpretation, reactive CHEETAH and Ignition and Growth modeling, as well as detail on possible future experiments. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  20. Microbeam facility extension for single-cell irradiation experiments. Investigations about bystander effect and reactive oxygen species impact

    International Nuclear Information System (INIS)

    Hanot, M.; Khodja, H.; Daudin, L.; Hoarau, J.; Carriere, M.; Gouget, B.

    2006-01-01

    , thus limiting the throughput to the mechanical performances of the XY culture dish stage. A piezo actuator stage will be used to promptly locate the collimator under the selected cells in order to enhance considerably the irradiation speed. A fluorescence in situ microscope (Olympus BX FM) is mounted on an anti vibration table surrounding the exit port. It is equipped with a CCD camera (Rope r Scientific) and images are acquired using Image Pro Plus software. Beam extraction is performed using a 100 nm Si 3 N 4 window and culture dishes are based on standard plastic Petri dishes with a 1 mm 2, 100 nm thick Si 3 N 4 insert at the centre. Ion detection is performed using a photo multiplier tube (Hamamatsu R7400 ) collecting photons emitted by a 9 pm BC400 foil inserted between the exit window and the culture dish. A fast signal is generated after ion traversal that triggers an electrostatic shutter based on a high voltage amplifier (Fisher GmbH). Result and discussion: For first microbeam experiments we used ROS17/2.8 osteoblastic cells. Cell: were grown in DMEM with supplements. One day before irradiation, cells were seeded on the 100 nm thick membrane with help of poly-lysine. Just one hour prior to the irradiation, cells were stained using Hoechst 33342 (0,2 pg/ml) to allow their spatial location using blue nuclear fluorescence. During irradiation, cells were maintained in their medium and the Petri dish was closed constantly. A 2 MeV alpha beam was extracted and current was reduced to few ions per second, and the Petri dish was placed over the exit window on different locations, thus covering a cumulated area limited to 5% of the Si 3 N 4 insert. Each irradiated cell received approximately 10 ions during the experiment, inducing a dose deposition estimated to 1 Gy/cell. (author)

  1. The PARET code and the analysis of the SPERT I transients

    Energy Technology Data Exchange (ETDEWEB)

    Woodruff, William L [Argonne National Laboratory, Argonne (United States)

    1983-09-01

    The PARET code has been adapted for the testing of methods and models and for subsequent use in the analysis of transient behavior in research reactors. Comparisons with the experimental results from the SPERT-I transients are provided. The code has also been applied to the analysis of the IAEA 10 MW benchmark cores for protected and unprotected transients. The PARET code was originally developed for the analysis of the SPERT-III experiments for temperatures and pressures typical of power reactors. This code has now been modified to include a selection of flow instability, departure from nucleate boiling (DNB), single and two-phase heat transfer correlations, and a properties library considered more applicable to the low pressures, temperatures, and flow rates encountered in research reactors. The PARET code provides a coupled thermal, hydraulic, and point kinetics capability with continuous reactivity feedback, and an optional voiding model which estimates the voiding produced by subcooled boiling. The present version of the PARET code provides a convenient means of assessing the various models and correlations proposed for use in the analysis of research reactor behavior. For comparison with experiments the SPERT-I cores B-24/32, B-12/64, and D-12/25 were chosen. The B-24/32 core is similar in design to many plate type research reactors in current operation, and the D-12/25 core is of interest because the test included both nondestructive and destructive transients.

  2. The PARET code and the analysis of the SPERT I transients

    International Nuclear Information System (INIS)

    Woodruff, William L.

    1983-01-01

    The PARET code has been adapted for the testing of methods and models and for subsequent use in the analysis of transient behavior in research reactors. Comparisons with the experimental results from the SPERT-I transients are provided. The code has also been applied to the analysis of the IAEA 10 MW benchmark cores for protected and unprotected transients. The PARET code was originally developed for the analysis of the SPERT-III experiments for temperatures and pressures typical of power reactors. This code has now been modified to include a selection of flow instability, departure from nucleate boiling (DNB), single and two-phase heat transfer correlations, and a properties library considered more applicable to the low pressures, temperatures, and flow rates encountered in research reactors. The PARET code provides a coupled thermal, hydraulic, and point kinetics capability with continuous reactivity feedback, and an optional voiding model which estimates the voiding produced by subcooled boiling. The present version of the PARET code provides a convenient means of assessing the various models and correlations proposed for use in the analysis of research reactor behavior. For comparison with experiments the SPERT-I cores B-24/32, B-12/64, and D-12/25 were chosen. The B-24/32 core is similar in design to many plate type research reactors in current operation, and the D-12/25 core is of interest because the test included both nondestructive and destructive transients

  3. Characterization of materials for a reactive transport model validation experiment: Interim report on the caisson experiment. Yucca Mountain Site Characterization Project

    International Nuclear Information System (INIS)

    Siegel, M.D.; Cheng, W.C.; Ward, D.B.; Bryan, C.R.

    1995-08-01

    Models used in performance assessment and site characterization activities related to nuclear waste disposal rely on simplified representations of solute/rock interactions, hydrologic flow field and the material properties of the rock layers surrounding the repository. A crucial element in the design of these models is the validity of these simplifying assumptions. An intermediate-scale experiment is being carried out at the Experimental Engineered Test Facility at Los Alamos Laboratory by the Los Alamos and Sandia National Laboratories to develop a strategy to validate key geochemical and hydrological assumptions in performance assessment models used by the Yucca Mountain Site Characterization Project

  4. Characterization of materials for a reactive transport model validation experiment: Interim report on the caisson experiment. Yucca Mountain Site Characterization Project

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, M.D.; Cheng, W.C. [Sandia National Labs., Albuquerque, NM (United States); Ward, D.B.; Bryan, C.R. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences

    1995-08-01

    Models used in performance assessment and site characterization activities related to nuclear waste disposal rely on simplified representations of solute/rock interactions, hydrologic flow field and the material properties of the rock layers surrounding the repository. A crucial element in the design of these models is the validity of these simplifying assumptions. An intermediate-scale experiment is being carried out at the Experimental Engineered Test Facility at Los Alamos Laboratory by the Los Alamos and Sandia National Laboratories to develop a strategy to validate key geochemical and hydrological assumptions in performance assessment models used by the Yucca Mountain Site Characterization Project.

  5. Solution High-Energy Burst Assembly (SHEBA) results from subprompt critical experiments with uranyl fluoride fuel

    International Nuclear Information System (INIS)

    Cappiello, C.C.; Butterfield, K.B.; Sanchez, R.G.; Bounds, J.A.; Kimpland, R.H.; Damjanovich, R.P.; Jaegers, P.J.

    1997-01-01

    Experiments were performed to measure a variety of parameters for SHEBA: behavior of the facility during transient and steady-state operation; characteristics of the SHEBA fuel; delayed-critical solution height vs solution temperature; initial reactor period and reactivity vs solution height; calibration of power level vs reactor power instrumentation readings; flux profile in SHEBA; radiation levels and neutron spectra outside the assembly for code verification and criticality alarm and dosimetry purposes; and effect on reactivity of voids in the fuel

  6. Detailed characterization and preliminary adsorption model for materials for an intermediate-scale reactive-transport experiment

    International Nuclear Information System (INIS)

    Ward, D.B.; Bryan, C.R.

    1994-01-01

    An experiment involving migration of fluid and tracers (Li, Br, Ni) through a 6-m-high x 3-m-dia caisson Wedron 510 sand, is being carried out for Yucca Mountain Site Characterization Project. Sand's surface chemistry of the sand was studied and a preliminary surface-complexation model of Ni adsorption formulated for transport calculations. XPS and leaching suggest that surface of the quartz sand is partially covered by thin layers of Fe-oxyhydroxide and Ca-Mg carbonate and by flakes of kaolinite. Ni adsorption by the sand is strongly pH-dependent, showing no adsorption at pH 5 and near-total adsorption at pH 7. Location of adsorption edge is independent of ionic strength and dissolved Ni concentration; it is shifted to slightly lower pH with higher pCO2 and to slightly higher pH by competition with Li. Diminished adsorption at alkiline pH with higher pCO2 implies formation of dissolved Ni-carbonato complexes. Ni adsorption edges for goethite and quartz, two components of the sand were also measured. Ni adsorption on pure quartz is only moderately pH-dependent and differs in shape and location from that of the sand, whereas Ni adsorption by goethite is strongly pH-dependent. A triple-layer surface-complexation model developed for goethite provides a good fit to the Ni-adsorption curve of the sand. Based on this model, the apparent surface area of the Fe-oxyhydroxide coating is estimated to be 560 m 2 /g, compatible with its occurrence as amorphous Fe-oxyhydroxide. Potentiometric titrations on sand also differ from pure quartz and suggest that effective surface area of sand may be much greater than that measured by N 2 -BET gas adsorption. Attempts to model the adsorption of bulk sand in terms of properties of pure end member components suggest that much of the sand surface is inert. Although the exact Ni adsorption mechanisms remain ambiguous, this preliminary adsorption model provides an initial set of parameters that can be used in transport calculations

  7. CREOLE experiment study on the reactivity temperature coefficient with sensitivity and uncertainty analysis using the MCNP5 code and different neutron cross section evaluations

    International Nuclear Information System (INIS)

    Boulaich, Y.; El Bardouni, T.; Erradi, L.; Chakir, E.; Boukhal, H.; Nacir, B.; El Younoussi, C.; El Bakkari, B.; Merroun, O.; Zoubair, M.

    2011-01-01

    Highlights: → In the present work, we have analyzed the CREOLE experiment on the reactivity temperature coefficient (RTC) by using the three-dimensional continuous energy code (MCNP5) and the last updated nuclear data evaluations. → Calculation-experiment discrepancies of the RTC were analyzed and the results have shown that the JENDL3.3 and JEFF3.1 evaluations give the most consistent values. → In order to specify the source of the relatively large discrepancy in the case of ENDF-BVII nuclear data evaluation, the k eff discrepancy between ENDF-BVII and JENDL3.3 was decomposed by using sensitivity and uncertainty analysis technique. - Abstract: In the present work, we analyze the CREOLE experiment on the reactivity temperature coefficient (RTC) by using the three-dimensional continuous energy code (MCNP5) and the last updated nuclear data evaluations. This experiment performed in the EOLE critical facility located at CEA/Cadarache, was mainly dedicated to the RTC studies for both UO 2 and UO 2 -PuO 2 PWR type lattices covering the whole temperature range from 20 deg. C to 300 deg. C. We have developed an accurate 3D model of the EOLE reactor by using the MCNP5 Monte Carlo code which guarantees a high level of fidelity in the description of different configurations at various temperatures taking into account their consequence on neutron cross section data and all thermal expansion effects. In this case, the remaining error between calculation and experiment will be awarded mainly to uncertainties on nuclear data. Our own cross section library was constructed by using NJOY99.259 code with point-wise nuclear data based on ENDF-BVII, JEFF3.1 and JENDL3.3 evaluation files. The MCNP model was validated through the axial and radial fission rate measurements at room and hot temperatures. Calculation-experiment discrepancies of the RTC were analyzed and the results have shown that the JENDL3.3 and JEFF3.1 evaluations give the most consistent values; the discrepancy is

  8. Weigle Reactivation in Acinetobacter Calcoaceticus

    DEFF Research Database (Denmark)

    Berenstein, Dvora

    1982-01-01

    phage and host survivals of about 5 times 10-6 and 1 times 10-1, respectively. Intracellular development of W-reactivated P78 was followed by one-step growth experiments. Conditions which allowed maximal W-reactivation also extended the period of phage production and yielded a somewhat reduced burst......Weigle (W)-reactivation was demonstrated in Acinetobacter calcoaceticus for the UV-irra-diated lysogenic phage P78. The reactivation factor (survival of irradiated phage on irradiated bacteria/ survival on unirradiated bacteria) reached a maximum value of 20. This was obtained at UV-doses giving...

  9. TRANSIENT ELECTRONICS CATEGORIZATION

    Science.gov (United States)

    2017-08-24

    AFRL-RY-WP-TR-2017-0169 TRANSIENT ELECTRONICS CATEGORIZATION Dr. Burhan Bayraktaroglu Devices for Sensing Branch Aerospace Components & Subsystems...SUBTITLE TRANSIENT ELECTRONICS CATEGORIZATION 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S) Dr. Burhan...88ABW-2017-3747, Clearance Date 31 July 2017. Paper contains color. 14. ABSTRACT Transient electronics is an emerging technology area that lacks proper

  10. Transient survivability of LMR oxide fuel pins

    International Nuclear Information System (INIS)

    Weber, E.T.; Pitner, A.L.; Bard, F.E.; Culley, G.E.; Hunter, C.W.

    1986-01-01

    Fuel pin integrity during transient events must be assessed for both the core design and safety analysis phases of a reactor project. A significant increase in the experience related to limits of integrity for oxide fuel pins in transient overpower events has been realized from testing of fuel pins irradiated in FFTF and PFR. Fourteen FFTF irradiated fuel pins were tested in TREAT, representing a range of burnups, overpower ramp rates and maximum overpower conditions. Results of these tests along with similar testing in the PFR/TREAT program, provide a demonstration of significant safety margins for oxide fuel pins. Useful information applied in analytical extrapolation of fuel pin test data have been developed from laboratory transient tests on irradiated fuel cladding (FCTT) and on unirradiated fuel pellet deformation. These refinements in oxide fuel transient performance are being applied in assessment of transient capabilities of long lifetime fuel designs using ferritic cladding

  11. Positive void reactivity

    International Nuclear Information System (INIS)

    Diamond, D.J.

    1992-09-01

    This report is a review of some of the important aspects of the analysis of large loss-of-coolant accidents (LOCAs). One important aspect is the calculation of positive void reactivity. To study this subject the lattice physics codes used for void worth calculations and the coupled neutronic and thermal-hydraulic codes used for the transient analysis are reviewed. Also reviewed are the measurements used to help validate the codes. The application of these codes to large LOCAs is studied with attention focused on the uncertainty factor for the void worth used to bias the results. Another aspect of the subject dealt with in the report is the acceptance criteria that are applied. This includes the criterion for peak fuel enthalpy and the question of whether prompt criticality should also be a criterion. To study the former, fuel behavior measurements and calculations are reviewed. (Author) (49 refs., 2 figs., tab.)

  12. Reactive transport of CO2-rich fluids in simulated wellbore interfaces : Flow-through experiments on the 1–6 m length scale

    NARCIS (Netherlands)

    Wolterbeek, Timotheus K.T.; Peach, Colin J.; Raoof, Amir; Spiers, Christopher J.

    2016-01-01

    Debonding at casing-cement interfaces poses a leakage pathway risk that may compromise well integrity in CO2 storage systems. The present study addresses the effects of long-range, CO2-induced, reactive transport on the conductance of such interfacial pathways. This is done by means of reactive

  13. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  14. Development of refined MCNPX-PARET multi-channel model for transient analysis in research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kalcheva, S.; Koonen, E. [SCK-CEN, BR2 Reactor Dept., Boeretang 200, 2400 Mol (Belgium); Olson, A. P. [RERTR Program, Nuclear Engineering Div., Argonne National Laboratory, Cass Avenue, Argonne, IL 60439 (United States)

    2012-07-01

    Reactivity insertion transients are often analyzed (RELAP, PARET) using a two-channel model, representing the hot assembly with specified power distribution and an average assembly representing the remainder of the core. For the analysis of protected by the reactor safety system transients and zero reactivity feedback coefficients this approximation proves to give adequate results. However, a more refined multi-channel model representing the various assemblies, coupled through the reactivity feedback effects to the whole reactor core is needed for the analysis of unprotected transients with excluded over power and period trips. In the present paper a detailed multi-channel PARET model has been developed which describes the reactor core in different clusters representing typical BR2 fuel assemblies. The distribution of power and reactivity feedback in each cluster of the reactor core is obtained from a best-estimate MCNPX calculation using the whole core geometry model of the BR2 reactor. The sensitivity of the reactor response to power, temperature and energy distributions is studied for protected and unprotected reactivity insertion transients, with zero and non-zero reactivity feedback coefficients. The detailed multi-channel model is compared vs. simplified fewer-channel models. The sensitivities of transient characteristics derived from the different models are tested on a few reactivity insertion transients with reactivity feedback from coolant temperature and density change. (authors)

  15. Spectroscopic classification of transients

    DEFF Research Database (Denmark)

    Stritzinger, M. D.; Fraser, M.; Hummelmose, N. N.

    2017-01-01

    We report the spectroscopic classification of several transients based on observations taken with the Nordic Optical Telescope (NOT) equipped with ALFOSC, over the nights 23-25 August 2017.......We report the spectroscopic classification of several transients based on observations taken with the Nordic Optical Telescope (NOT) equipped with ALFOSC, over the nights 23-25 August 2017....

  16. Transient burnout in flow reduction condition

    International Nuclear Information System (INIS)

    Iwamura, Takamichi; Kuroyanagi, Toshiyuki

    1981-01-01

    A transient flow reduction burnout experiment was conducted with water in a uniformly heated, vertically oriented tube. Test pressures ranged from 0.5 to 3.9 MPa. An analytical method was developed to obtain transient burnout conditions at the exit. A simple correlation to predict the deviation of the transient burnout mass velocity at the tube exit from the steady state mass velocity obtained as a function of steam-water density ratio and flow reduction rate. The correlation was also compared with the other data. (author)

  17. Serum biomarkers and transient elastography as predictors of advanced liver fibrosis in a United States cohort: the Boston children's hospital experience.

    Science.gov (United States)

    Lee, Christine K; Perez-Atayde, Antonio R; Mitchell, Paul D; Raza, Roshan; Afdhal, Nezam H; Jonas, Maureen M

    2013-10-01

    To evaluate and compare the ability of serum hyaluronic acid (HA) and human cartilage glycoprotein-39 (YKL-40) values, as well as transient elastography (TE) findings, to predict advanced hepatic fibrosis in a cohort from a single pediatric center. Subjects who underwent liver biopsy analysis within 12 months before enrollment were eligible for this prospective study. HA and YKL-40 measurements were obtained within 1 month of TE. A METAVIR score of F3 or F4 was considered to indicate advanced fibrosis. A total of 128 patients (51% males) aged 1.4 months to 27.6 years (22% aged blood tests and TE. For the prediction of advanced fibrosis, the area under the receiver operating characteristic curve (AUC) values were 0.83 for TE, 0.72 for HA, and 0.52 for YKL-40. The AUC of 0.83 for TE was statistically significantly greater than the AUCs for HA (P = .03) and YKL-40 (P fibrosis were 8.6 kPa for TE (P fibrosis (P = .15). In this study, which evaluated TE, HA, and YKL-40 to predict liver fibrosis in children in the US, YKL-40 had no predictive value and TE was superior to HA, but the addition of HA did not improve the performance of TE. Our data suggest that TE and HA may be useful noninvasive tools for assessing liver fibrosis in children. Copyright © 2013 Mosby, Inc. All rights reserved.

  18. Assessment of RELAP5/MOD3.1 with the LSTF SB-SG-06 experiment simulating a steam generator tube rupture transient

    International Nuclear Information System (INIS)

    Seul, K.W.; Bang, Y.S.; Lee, S.; Kim, H.J.

    1996-09-01

    The objective of the present work is to identify the predictability of RELAP5/MOD3.1 regarding thermal-hydraulic behavior during a steam generator tube rupture (SGTR). To evaluate the computed results, LSTF SB-SG-06 test data simulating the SGTR that occurred at the Mihama Unit 2 in 1991 are used. Also, some sensitivity studies of the code change in RELAP5, the break simulation model, and the break valve discharge coefficient are performed. The calculation results indicate that the RELAP5/MOD3.1 code predicted well the sequence of events and the major phenomena during the transient, such as the asymmetric loop behavior, reactor coolant system (RCS) cooldown and heat transfer by natural circulation, the primary and secondary system depressurization by the pressurizer auxiliary spray and the steam dump using the intact loop steam generator (SG) relief valve, and so on. However, there are some differences from the experimental data in the number of the relief valve cycling in the affected SG, and the flow regime of the hot leg with the pressurizer, and the break flow rates. Finally, the calculation also indicates that the coolant in the core could remain in a subcooled state as a result of the heat transfer caused by the natural circulation flow even if the reactor coolant pumps (RCPs) turned off and that the affected SG could be properly isolated to minimize the radiological release after the SGTR

  19. Assessment of RELAP5/MOD3.1 with the LSTF SB-SG-06 experiment simulating a steam generator tube rupture transient

    Energy Technology Data Exchange (ETDEWEB)

    Seul, K.W.; Bang, Y.S.; Lee, S.; Kim, H.J. [Korea Inst. of Nuclear Safety, Taejon (Korea, Republic of)

    1996-09-01

    The objective of the present work is to identify the predictability of RELAP5/MOD3.1 regarding thermal-hydraulic behavior during a steam generator tube rupture (SGTR). To evaluate the computed results, LSTF SB-SG-06 test data simulating the SGTR that occurred at the Mihama Unit 2 in 1991 are used. Also, some sensitivity studies of the code change in RELAP5, the break simulation model, and the break valve discharge coefficient are performed. The calculation results indicate that the RELAP5/MOD3.1 code predicted well the sequence of events and the major phenomena during the transient, such as the asymmetric loop behavior, reactor coolant system (RCS) cooldown and heat transfer by natural circulation, the primary and secondary system depressurization by the pressurizer auxiliary spray and the steam dump using the intact loop steam generator (SG) relief valve, and so on. However, there are some differences from the experimental data in the number of the relief valve cycling in the affected SG, and the flow regime of the hot leg with the pressurizer, and the break flow rates. Finally, the calculation also indicates that the coolant in the core could remain in a subcooled state as a result of the heat transfer caused by the natural circulation flow even if the reactor coolant pumps (RCPs) turned off and that the affected SG could be properly isolated to minimize the radiological release after the SGTR.

  20. Reactivity worth measurement of the control blades of the University of Florida training reactor

    International Nuclear Information System (INIS)

    Quintero-Leyva, Barbaro

    1997-01-01

    A series of experiments were carried out in order to measure the reactivity worth of the safety and regulating blades of the University of Florida Training Reactor (UFTR) using the Inverse Kinetics, the Inverse Kinetics-Rod Drop method and the Power Ratio. The reactor's own instrumentation (compensated ion chamber) and an independent counting system (fission chamber) were used. A very smooth exponential decay of the flux was observed after 6s of the beginning of the transients using the reading of the reactor detector. The results of the measurements of the reactivity using both detectors were consistent and in good agreement. The compensated ion chamber showed a very smooth exponential behavior; this suggests that if we could record the power for a small sample time, say 0.1 s from the beginning of the transient, several additional research projects could be accomplished. First, precise intercomparison of the methods could be achieved if the statistics level is acceptable. Second, a precise description of the bouncing of the blades and its effects on the reactivity could be achieved. Finally, the design of a reactivity-meter could be based on such study. (author)

  1. Fast thermal transients on valve

    International Nuclear Information System (INIS)

    Ferjancic, M.; Stok, B.; Halilovic, M.; Koc, P.; Mole, N.; Otrin, Z.; Kotar, A.

    2007-01-01

    One of the regulatory body methods to supervise nuclear safety of a nuclear power plant is a review of plant modifications and evaluation of their impact on plant operating experience. The Slovenian Nuclear Safety Administration (SNSA) licensed in April 2003 the use of leak-before-break (LBB) methodology in the Krsko NPP for the primary loop including surge line and connecting pipelines with minimal diameter of 6 inch. The SNSA decision based also on fracture mechanics analyses that include direct pipe failure mechanisms such as water hammer, creep damage, erosion and corrosion, fatigue and environmental conditions over the entire life of the plant. The evaluation of the operating transients pointed out, that presumed loadings, used for the LBB analysis, did not incorporate all the fast thermal transients data. For that purpose the SNSA requested Faculty of Mechanical Engineering (FS) in Ljubljana to perform additional analyses. The results of the analysis shall confirm the validity of the LBB analysis. (author)

  2. Advanced Instrumentation for Transient Reactor Testing

    Energy Technology Data Exchange (ETDEWEB)

    Corradini, Michael L.; Anderson, Mark; Imel, George; Blue, Tom; Roberts, Jeremy; Davis, Kurt

    2018-01-31

    Transient testing involves placing fuel or material into the core of specialized materials test reactors that are capable of simulating a range of design basis accidents, including reactivity insertion accidents, that require the reactor produce short bursts of intense highpower neutron flux and gamma radiation. Testing fuel behavior in a prototypic neutron environment under high-power, accident-simulation conditions is a key step in licensing nuclear fuels for use in existing and future nuclear power plants. Transient testing of nuclear fuels is needed to develop and prove the safety basis for advanced reactors and fuels. In addition, modern fuel development and design increasingly relies on modeling and simulation efforts that must be informed and validated using specially designed material performance separate effects studies. These studies will require experimental facilities that are able to support variable scale, highly instrumented tests providing data that have appropriate spatial and temporal resolution. Finally, there are efforts now underway to develop advanced light water reactor (LWR) fuels with enhanced performance and accident tolerance. These advanced reactor designs will also require new fuel types. These new fuels need to be tested in a controlled environment in order to learn how they respond to accident conditions. For these applications, transient reactor testing is needed to help design fuels with improved performance. In order to maximize the value of transient testing, there is a need for in-situ transient realtime imaging technology (e.g., the neutron detection and imaging system like the hodoscope) to see fuel motion during rapid transient excursions with a higher degree of spatial and temporal resolution and accuracy. There also exists a need for new small, compact local sensors and instrumentation that are capable of collecting data during transients (e.g., local displacements, temperatures, thermal conductivity, neutron flux, etc.).

  3. IN SITU DESTRUCTION OF CHLORINATED HYDROCARBON COMPOUNDS IN GROUNDWATER USING CATALYTIC REDUCTIVE REDUCTIVE DEHALOGENATION IN A REACTIVE WELL: TESTING AND OPERATIONAL EXPERIENCES. (R825421)

    Science.gov (United States)

    A groundwater treatment technology based on catalytic reductive dehalogenation has been developed to efficiently destroy chlorinated hydrocarbons in situ using a reactive well approach. The treatment process utilizes dissolved H2 as an electron donor, in...

  4. Transient Droplet Behavior and Droplet Breakup during Bulk and Confined Shear Flow in Blends with One Viscoelastic Component: Experiments, Modelling and Simulations

    Science.gov (United States)

    Cardinaels, Ruth; Verhulst, Kristof; Renardy, Yuriko; Moldenaers, Paula

    2008-07-01

    The transient droplet deformation and droplet orientation after inception of shear, the shape relaxation after cessation of shear and droplet breakup during shear, are microscopically studied, both under bulk and confined conditions. The studied blends contain one viscoelastic Boger fluid phase. A counter rotating setup, based on a Paar Physica MCR300, is used for the droplet visualisation. For bulk shear flow, it is shown that the droplet deformation during startup of shear flow and the shape relaxation after cessation of shear flow are hardly influenced by droplet viscoelasticity, even at moderate to high capillary and Deborah numbers. The effects of droplet viscoelasticity only become visible close to the critical conditions and a novel break-up mechanism is observed. Matrix viscoelasticity has a more pronounced effect, causing overshoots in the deformation and significantly inhibiting relaxation. However, different applied capillary numbers prior to cessation of shear flow, with the Deborah number fixed, still result in a single master curve for shape retraction, as in fully Newtonian systems. The long tail in the droplet relaxation can be qualitatively described with a phenomenological model for droplet deformation, when using a 5-mode Giesekus model for the fluid rheology. It is found that the shear flow history significantly affects the droplet shape evolution and the breakup process in blends with one viscoelastic component. Confining a droplet between two plates accelerates the droplet deformation kinetics, similar to fully Newtonian systems. However, the increased droplet deformation, due to wall effects, causes the steady state to be reached at a later instant in time. Droplet relaxation is less sensitive to confinement, leading to slower relaxation kinetics only for highly confined droplets. For the blend with a viscoelastic droplet, a non-monotonous trend is found for the critical capillary number as a function of the confinement ratio. Finally

  5. Transient Droplet Behavior and Droplet Breakup during Bulk and Confined Shear Flow in Blends with One Viscoelastic Component: Experiments, Modelling and Simulations

    International Nuclear Information System (INIS)

    Cardinaels, Ruth; Verhulst, Kristof; Moldenaers, Paula; Renardy, Yuriko

    2008-01-01

    The transient droplet deformation and droplet orientation after inception of shear, the shape relaxation after cessation of shear and droplet breakup during shear, are microscopically studied, both under bulk and confined conditions. The studied blends contain one viscoelastic Boger fluid phase. A counter rotating setup, based on a Paar Physica MCR300, is used for the droplet visualisation. For bulk shear flow, it is shown that the droplet deformation during startup of shear flow and the shape relaxation after cessation of shear flow are hardly influenced by droplet viscoelasticity, even at moderate to high capillary and Deborah numbers. The effects of droplet viscoelasticity only become visible close to the critical conditions and a novel break-up mechanism is observed. Matrix viscoelasticity has a more pronounced effect, causing overshoots in the deformation and significantly inhibiting relaxation. However, different applied capillary numbers prior to cessation of shear flow, with the Deborah number fixed, still result in a single master curve for shape retraction, as in fully Newtonian systems. The long tail in the droplet relaxation can be qualitatively described with a phenomenological model for droplet deformation, when using a 5-mode Giesekus model for the fluid rheology. It is found that the shear flow history significantly affects the droplet shape evolution and the breakup process in blends with one viscoelastic component. Confining a droplet between two plates accelerates the droplet deformation kinetics, similar to fully Newtonian systems. However, the increased droplet deformation, due to wall effects, causes the steady state to be reached at a later instant in time. Droplet relaxation is less sensitive to confinement, leading to slower relaxation kinetics only for highly confined droplets. For the blend with a viscoelastic droplet, a non-monotonous trend is found for the critical capillary number as a function of the confinement ratio. Finally

  6. Summary of transient analysis

    International Nuclear Information System (INIS)

    Saha, P.

    1984-01-01

    This chapter reviews the papers on the pressurized water reactor (PWR) and boiling water reactor (BWR) transient analyses given at the American Nuclear Society Topical Meeting on Anticipated and Abnormal Plant Transients in Light Water Reactors. Most of the papers were based on the systems calculations performed using the TRAC-PWR, RELAP5 and RETRAN codes. The status of the nuclear industry in the code applications area is discussed. It is concluded that even though comprehensive computer codes are available for plant transient analysis, there is still a need to exercise engineering judgment, simpler tools and even hand calculations to supplement these codes

  7. Pius, self-protective thermohydraulics transient without safety system intervention

    International Nuclear Information System (INIS)

    Fredell, J.; Bredolt, V.

    1989-01-01

    In this paper, the self-protective thermohydraulic feedback of the PIUS reactor system is illustrated by an in-depth discussion of one typical transient. The selected transient is an undetected total loss of feedwater in the complete absence of conventional safety system intervention. The reactor shuts itself down to residual power in two steps. First, the power decreases due to the strongly negative moderator temperature reactivity coefficient, and then a complete shutdown occurs by ingress of cold, highly borated water from the reactor pool. The transient is terminated without any harm to the fuel or paint systems

  8. Benthic metal fluxes and sediment diagenesis in a water reservoir affected by acid mine drainage: A laboratory experiment and reactive transport modeling

    Science.gov (United States)

    Torres, E.; Ayora, C.; Jiménez-Arias, J. L.; García-Robledo, E.; Papaspyrou, S.; Corzo, A.

    2014-08-01

    Reservoirs are one of the primary water supply sources. Knowledge of the metal fluxes at the water-sediment interfaces of reservoirs is essential for predicting their ecological quality. Redox oscillations in the water column are promoted by stratification; turnover events may significantly alter metal cycling, especially in reservoirs impacted by acid mine drainage (AMD). To study this phenomenon, an experiment was performed under controlled laboratory conditions. Sediment cores from an AMD-affected reservoir were maintained in a tank with reservoir water for approximately two months and subjected to alternating oxic-hypoxic conditions. A detailed metal speciation in solid phases of the sediment was initially performed by sequential extraction, and pore water was analyzed at the end of each redox period. Tank water metals concentrations were systematically monitored throughout the experiment. The experimental results were then used to calibrate a diffusion-reaction model and quantify the reaction rates and sediment-water fluxes. Under oxic conditions, pH, Fe and As concentrations decreased in the tank due to schwertmannite precipitation, whereas the concentrations of Al, Zn, Cu, Ni, and Co increased due to Al(OH)3 and sulfide dissolution. The reverse trends occurred under hypoxic conditions. Under oxic conditions, the fluxes calculated by applying Fick’s first law to experimental concentration gradients contradicted the fluxes expected based on the evolution of the tank water. According to the reactive transport calculations, this discrepancy can be attributed to the coarse resolution of sediment sampling. The one-cm-thick slices failed to capture effectively the notably narrow (1-2 mm) concentration peaks of several elements in the shallow pore water resulting from sulfide and Al(OH)3 dissolution. The diffusion-reaction model, extended to the complete year, computed that between 25% and 50% of the trace metals and less than 10% of the Al that precipitated under

  9. PWR systems transient analysis

    International Nuclear Information System (INIS)

    Kennedy, M.F.; Peeler, G.B.; Abramson, P.B.

    1985-01-01

    Analysis of transients in pressurized water reactor (PWR) systems involves the assessment of the response of the total plant, including primary and secondary coolant systems, steam piping and turbine (possibly including the complete feedwater train), and various control and safety systems. Transient analysis is performed as part of the plant safety analysis to insure the adequacy of the reactor design and operating procedures and to verify the applicable plant emergency guidelines. Event sequences which must be examined are developed by considering possible failures or maloperations of plant components. These vary in severity (and calculational difficulty) from a series of normal operational transients, such as minor load changes, reactor trips, valve and pump malfunctions, up to the double-ended guillotine rupture of a primary reactor coolant system pipe known as a Large Break Loss of Coolant Accident (LBLOCA). The focus of this paper is the analysis of all those transients and accidents except loss of coolant accidents

  10. Transient multivariable sensor evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, Richard B.; Heifetz, Alexander

    2017-02-21

    A method and system for performing transient multivariable sensor evaluation. The method and system includes a computer system for identifying a model form, providing training measurement data, generating a basis vector, monitoring system data from sensor, loading the system data in a non-transient memory, performing an estimation to provide desired data and comparing the system data to the desired data and outputting an alarm for a defective sensor.

  11. The economic impact of reactor transients

    International Nuclear Information System (INIS)

    Rossin, A.D.; Vine, G.L.

    1984-01-01

    This chapter discusses the cost estimation of transients and the causal relationship between transients and accidents. It is suggested that the calculation of the actual cost of a transient that has occurred is impossible without computerized records. Six months of operating experience reports, based on a survey of pressurized water reactors (PWRs) and boiling water reactors (BWRs) conducted by the Nuclear Safety Analysis Center (NSAC), are analyzed. The significant costs of a reactor transient are the repair costs resulting from severe damage to plant equipment, the cost of scrams (the actions the system is designed to take to avoid safety risks), US NRC fines, negative publicity, utility rates and revenues. It is estimated that the Three Mile Island-2 accident cost the US over $100 billion in nuclear plant delays and cancellations, more expensive fuel, oil imports, backfits, bureaucratic, administrative and legal costs, and lost productivity

  12. Development of a transient criticality evaluation method

    International Nuclear Information System (INIS)

    Pain, C.C.; Eaton, M.D.; Miles, B.; Ziver, A.K.; Gomes, J.L.M.A.; Umpleby, A.P.; Piggott, M.D.; Goddard, A.J.H.; Oliveira, C.R.E. de

    2005-01-01

    In developing a transient criticality evaluation method we model, in full spatial/temporal detail, the neutron fluxes and consequent power and the evolving material properties - their flows, energies, phase changes etc. These methods are embodied in the generic method FETCH code which is based as far as possible on basic principles and is capable of use in exploring safety-related situations somewhat beyond the range of experiment. FETCH is a general geometry code capable of addressing a range of criticality issues in fissile materials. The code embodies both transient radiation transport and transient fluid dynamics. Work on powders, granular materials, porous media and solutions is reviewed. The capability for modelling transient criticality for chemical plant, waste matrices and advanced reactors is also outlined. (author)

  13. External Quality Control for Dried Blood Spot Based C-reactive Protein Assay: Experience from the Indonesia Family Life Survey and the Longitudinal Aging Study in India

    Science.gov (United States)

    Hu, Peifeng; Herningtyas, Elizabeth H.; Kale, Varsha; Crimmins, Eileen M.; Risbud, Arun R.; McCreath, Heather; Lee, Jinkook; Strauss, John; O’Brien, Jennifer C.; Bloom, David E.; Seeman, Teresa E.

    2015-01-01

    Measurement of C-reactive protein, a marker of inflammation, in dried blood spots has been increasingly incorporated in community-based social surveys internationally. Although the dried blood spot based CRP assay protocol has been validated in the United States, it remains unclear whether laboratories in other less developed countries can generate C-reactive protein results of similar quality. We therefore conducted external quality monitoring for dried blood spot based C-reactive protein measurement for the Indonesia Family Life Survey and the Longitudinal Aging Study in India. Our results show that dried blood spot based C-reactive protein results in these two countries have excellent and consistent correlations with serum-based values and dried blood spot based results from the reference laboratory in the United States. Even though the results from duplicate samples may have fluctuations in absolute values over time, the relative order of C-reactive protein levels remains similar and the estimates are reasonably precise for population-based studies that investigate the association between socioeconomic factors and health. PMID:25879265

  14. Pressurizer and steam-generator behavior under PWR transient conditions

    International Nuclear Information System (INIS)

    Wahba, A.B.; Berta, V.T.; Pointner, W.

    1983-01-01

    Experiments have been conducted in the Loss-of-Fluid Test (LOFT) pressurized water reactor (PWR), at the Idaho National Engineering Laboratory, in which transient phenomena arising from accident events with and without reactor scram were studied. The main purpose of the LOFT facility is to provide data for the development of computer codes for PWR transient analyses. Significant thermal-hydraulic differences have been observed between the measured and calculated results for those transients in which the pressurizer and steam generator strongly influence the dominant transient phenomena. Pressurizer and steam generator phenomena that occurred during four specific PWR transients in the LOFT facility are discussed. Two transients were accompanied by pressurizer inflow and a reduction of the heat transfer in the steam generator to a very small value. The other two transients were accompanied by pressurizer outflow while the steam generator behavior was controlled

  15. Transient flow combustion

    Science.gov (United States)

    Tacina, R. R.

    1984-01-01

    Non-steady combustion problems can result from engine sources such as accelerations, decelerations, nozzle adjustments, augmentor ignition, and air perturbations into and out of the compressor. Also non-steady combustion can be generated internally from combustion instability or self-induced oscillations. A premixed-prevaporized combustor would be particularly sensitive to flow transients because of its susceptability to flashback-autoignition and blowout. An experimental program, the Transient Flow Combustion Study is in progress to study the effects of air and fuel flow transients on a premixed-prevaporized combustor. Preliminary tests performed at an inlet air temperature of 600 K, a reference velocity of 30 m/s, and a pressure of 700 kPa. The airflow was reduced to 1/3 of its original value in a 40 ms ramp before flashback occurred. Ramping the airflow up has shown that blowout is more sensitive than flashback to flow transients. Blowout occurred with a 25 percent increase in airflow (at a constant fuel-air ratio) in a 20 ms ramp. Combustion resonance was found at some conditions and may be important in determining the effects of flow transients.

  16. Experimental validation of Pu-Sm evolution model for CANDU-6 power transients

    International Nuclear Information System (INIS)

    Coutsiers, Eduardo E.; Pomerantz, Marcelo E.; Moreno, Carlos A.

    2000-01-01

    Development of a methodology to evaluate the reactivity produced by Pu-Sm transient, effect displayed after power transients. This methodology allows to predict the behavior of liquid zones with which the fine control of CANDU reactor power is made. With this information, it is easier to foresee the refueling demand after power movements. The comparison with experimental results showed good agreement. (author)

  17. Analysis of transients in the SRP test pile

    International Nuclear Information System (INIS)

    Church, J.P.

    1976-11-01

    Analysis of the hypothetical upper limit accident in the Savannah River Test Pile showed that the offsite thyroid dose from fission product release would be -3 of the 10-CFR-100 guideline dose for 95 percent of measured meteorological conditions. Offsite whole body dose would be negligible. The Test Pile was modified to limit the length of test piece that can be charged to the pile. These modifications reduce the potential offsite dose to -5 of the regulatory guidelines. Assessment of Test Pile safety included calculations of transients initiated by a variety of reactivity additions that were either terminated or not terminated by safety systems. Reactivity addition mechanisms considered were abnormally driving control rods out of the pile and charging abnormal test pieces into the pile. The transients were evaluated in the adiabatic approximation in which three-dimensional calculations of static flux shapes and reactivity were superimposed on point reactor kinetics calculations. Negative reactivity feedback effects appropriate for the pile and the temperature dependence of material properties, such as specific heat and thermal conductivity, were included. The results show that, for the worst initiators, safety systems can prevent the temperature rise from exceeding 1 0 C anywhere in the Test Pile. If the safety systems do not function, the pile temperatures will increase until the transient is ended by the inherent negative reactivity effects, including the melting of some fuel

  18. A technique for computing bowing reactivity feedback in LMFBR's

    International Nuclear Information System (INIS)

    Finck, P.J.

    1987-01-01

    During normal or accidental transients occurring in a LMFBR core, the assemblies and their support structure are subjected to important thermal gradients which induce differential thermal expansions of the walls of the hexcans and differential displacement of the assembly support structure. These displacements, combined with the creep and swelling of structural materials, remain quite small, but the resulting reactivity changes constitute a significant component of the reactivity feedback coefficients used in safety analyses. It would be prohibitive to compute the reactivity changes due to all transients. Thus, the usual practice is to generate reactivity gradient tables. The purpose of the work presented here is twofold: develop and validate an efficient and accurate scheme for computing these reactivity tables; and to qualify this scheme

  19. Transient hardened power FETs

    International Nuclear Information System (INIS)

    Dawes, W.R. Jr.; Fischer, T.A.; Huang, C.C.C.; Meyer, W.J.; Smith, C.S.; Blanchard, R.A.; Fortier, T.J.

    1986-01-01

    N-channel power FETs offer significant advantages in power conditioning circuits. Similiarily to all MOS technologies, power FET devices are vulnerable to ionizing radiation, and are particularily susceptible to burn-out in high dose rate irradiations (>1E10 rads(Si)/sec.), which precludes their use in many military environments. This paper will summarize the physical mechanisms responsible for burn-out, and discuss various fabrication techniques designed to improve the transient hardness of power FETs. Power FET devices were fabricated with several of these techniques, and data will be presented which demonstrates that transient hardness levels in excess of 1E12 rads(Si)/sec. are easily achievable

  20. Transients in the Vivitron

    International Nuclear Information System (INIS)

    Cooke, C.M.; Frick, G.; Roumie, M.

    1993-01-01

    Electrical measurements are presented for the construction of a model for the study of transients in the Vivitron. Observation of the transmission of electrical pulses in the porticos clearly shows transmission-line behaviour. Measurements of the vector impedance of the outer porticos show the same transmission-line properties, but also gives a description of the modification from a pure transmission line due to the circular electrodes. The results of this investigation should allow the construction of a computer model which predicts the evolution of the transients in the case of a spark in the Vivitron. (orig.)

  1. Two-frequency, one-detector reactivity system (TFODRS)

    International Nuclear Information System (INIS)

    Sachs, R.D.; Woodall, D.M.

    1985-01-01

    A two-frequency, one-detector reactivity system (TFODRS) was experimentally verified on the University of New Mexico (UNM) AGN-201M thermal reactor. That system was used to obtain the absolute steady-state reactivity and to demonstrate the feasibility of acquiring the transient reactivity. A detailed description of TFODRS hardware and software is given in this paper. The TFODRS obtains the absolute and net reactivity by computing the frequency spectrum of the reactor neutron-detector signal. The ratio of the high-frequency to the low-frequency components about an empirical break point is used to determine the reactivity. The TFODRS was successfully used to measure a known AGN-201M steady-state reactivity, with a relative error of 18%. TFODRS transient curves as a function of reactivity were shown to be different from the steady-state curves. The transient curves appear to be a function of the rate of reactivity insertion. The authors speculate that a modified TFODRS, using state-of-the-art microprocessors, could be used for fast reactors. The TFODRS is not presently a practicable reactimeter. However, with more research and development, it is felt it could be used in near-term nuclear industry applications, such as monitoring fuel storage pools

  2. The effect of core configuration on temperature coefficient of reactivity in IRR-1

    Energy Technology Data Exchange (ETDEWEB)

    Bettan, M.; Silverman, I.; Shapira, M.; Nagler, A. [Soreq Nuclear Research Center, Yavne (Israel)

    1997-08-01

    Experiments designed to measure the effect of coolant moderator temperature on core reactivity in an HEU swimming pool type reactor were performed. The moderator temperature coefficient of reactivity ({alpha}{sub {omega}}) was obtained and found to be different in two core loadings. The measured {alpha}{sub {omega}} of one core loading was {minus}13 pcm/{degrees}C at the temperature range of 23-30{degrees}C. This value of {alpha}{sub {omega}} is comparable to the data published by the IAEA. The {alpha}{sub {omega}} measured in the second core loading was found to be {minus}8 pcm/{degrees}C at the same temperature range. Another phenomenon considered in this study is core behavior during reactivity insertion transient. The results were compared to a core simulation using the Dynamic Simulator for Nuclear Power Plants. It was found that in the second core loading factors other than the moderator temperature influence the core reactivity more than expected. These effects proved to be extremely dependent on core configuration and may in certain core loadings render the reactor`s reactivity coefficient undesirable.

  3. An Appetitive Experience after Fear Memory Destabilization Attenuates Fear Retention: Involvement GluN2B-NMDA Receptors in the Basolateral Amygdala Complex

    Science.gov (United States)

    Ferrer Monti, Roque I.; Giachero, Marcelo; Alfei, Joaquín M.; Bueno, Adrián M.; Cuadra, Gabriel; Molina, Victor A.

    2016-01-01

    It is known that a consolidated memory can return to a labile state and become transiently malleable following reactivation. This instability is followed by a restabilization phase termed reconsolidation. In this work, we explored whether an unrelated appetitive experience (voluntary consumption of diluted sucrose) can affect a contextual fear…

  4. The reactivity meter and core reactivity

    International Nuclear Information System (INIS)

    Siltanen, P.

    1999-01-01

    This paper discussed in depth the point kinetic equations and the characteristics of the point kinetic reactivity meter, particularly for large negative reactivities. From a given input signal representing the neutron flux seen by a detector, the meter computes a value of reactivity in dollars (ρ/β), based on inverse point kinetics. The prompt jump point of view is emphasised. (Author)

  5. Experimental evaluation of reactivity constraints for the closed-loop control of reactor power

    International Nuclear Information System (INIS)

    Bernard, J.A.; Lanning, D.D.; Ray, A.

    1984-01-01

    General principles for the closed-loop, digital control of reactor power have been identified, quantitatively enumerated, and experimentally demonstrated on the 5 MWt Research Reactor, MITR-II. The basic concept is to restrict the net reactivity so that it is always possible to make the reactor period infinite at the desired termination point of a transient by reversing the direction of motion of whatever control mechanism is associated with the controller. This capability is formally referred to as ''feasibility of control''. A series of ten experiments have been conducted over a period of eighteen months to demonstrate the efficacy of this property for the automatic control of reactor power. It has been shown that a controller which possesses this property is capable of both raising and lowering power in a safe, efficient manner while using a control rod of varying differential worth, that the reactivity constraints are a sufficient condition for the automatic control of reactor power, and that the use of a controller based on reactivity constraints can prevent overshoots either due to attempts to control a transient with a control rod of insufficient differential worth or due to failure to properly estimate when to commence rod insertion. Details of several of the more significant tests are presented together with a discussion of the rationale for the development of closed-loop control in large commercial power systems. Specific consideration is given to the motivation for designing a controller based on feasibility of control and the associated licensing issues

  6. Transient Heat Conduction

    DEFF Research Database (Denmark)

    Rode, Carsten

    1998-01-01

    Analytical theory of transient heat conduction.Fourier's law. General heat conducation equation. Thermal diffusivity. Biot and Fourier numbers. Lumped analysis and time constant. Semi-infinite body: fixed surface temperature, convective heat transfer at the surface, or constant surface heat flux...

  7. Transient cavitation in pipelines

    NARCIS (Netherlands)

    Kranenburg, C.

    1974-01-01

    The aim of the present study is to set up a one-dimensional mathematical model, which describes the transient flow in pipelines, taking into account the influence of cavitation and free gas. The flow will be conceived of as a three-phase flow of the liquid, its vapour and non-condensible gas. The

  8. Healthy Active Duty Military with Lifetime Experience of Mild Traumatic Brain Injury Exhibits Subtle Deficits in Sensory Reactivity and Sensory Integration During Static Balance.

    Science.gov (United States)

    Wright, W Geoffrey; Handy, Justin D; Avcu, Pelin; Ortiz, Alejandro; Haran, F Jay; Doria, Michael; Servatius, Richard J

    2018-03-01

    Postural control and stress reactivity were investigated in active duty coast guard personnel to determine whether they are sensitive to lifetime effects of mild traumatic brain injury (mTBI). A custom-designed and validated virtual reality-based computerized posturography device was used to assess postural stability, whereas emotional reactivity was assessed using the acoustic startle response (ASR), and neurocognitive performance was assessed using the defense-automated neurobehavioral assessment (DANA). It was hypothesized that residual and subtle postural control imbalance and deficits in cognitive and sensory reactivity would be evident in those reporting multiple lifetime mTBI. Active duty military personnel (N = 36; 7 females and 29 males) with no Deployment Limiting Medical Condition were recruited and tested on all assessments. Medical history information provided a history of head injury. Thirty-nine percent of participants reported having a previous mTBI (nine reporting one and five reporting more than one incident). No participant had experienced a head injury within the past year and all were symptom free. A significant effect of number of mTBI was found in the postural assessment (p = 0.002). Lifetime mTBI was associated with suppressed ASR magnitude (p = 0.03) but did not affect neurocognitive performance. The current findings provide new insight into ongoing controversies concerning sensitivity to functional deficits following mTBI and when the window for treatment or restoration ends.

  9. Temperature transient response measurement in flowing water

    International Nuclear Information System (INIS)

    Rainbird, J.C.

    1980-01-01

    A specially developed procedure is described for determining the thermal transient response of thermocouples and other temperature transducers when totally immersed in flowing water. The high velocity heat transfer conditions associated with this facility enable thermocouple response times to be predicted in other fluids. These predictions can be confirmed by electrical analogue experiments. (author)

  10. Compressive Transient Imaging

    KAUST Repository

    Sun, Qilin

    2017-04-01

    High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

  11. Heat shock and herpes virus: enhanced reactivation without untargeted mutagenesis

    International Nuclear Information System (INIS)

    Lytle, C.D.; Carney, P.G.

    1988-01-01

    Enhanced reactivation of Ultraviolet-irradiated virus has been reported to occur in heat-shocked host cells. Since enhanced virus reactivation is often accompanied by untargeted mutagenesis, we investigated whether such mutagenesis would occur for herpes simplex virus (HSV) in CV-1 monkey kidney cells subjected to heat shock. In addition to expressing enhanced reactivation, the treated cells were transiently more susceptible to infection by unirradiated HSV. No mutagenesis of unirradiated HSV was found whether infection occurred at the time of increased susceptibility to infection or during expression of enhanced viral reactivation

  12. Actinide and Xenon reactivity effects in ATW high flux systems

    International Nuclear Information System (INIS)

    Woosley, M.; Olson, K.; Henderson, D.L.

    1995-01-01

    In this paper, initial system reactivity response to flux changes caused by the actinides and xenon are investigated separately for a high flux ATW system. The maximum change in reactivity after a flux change due to the effect of the changing quantities of actinides is generally at least two orders of magnitude smaller than either the positive or negative reactivity effect associated with xenon after a shutdown or start-up. In any transient flux event, the reactivity response of the system to xenon will generally occlude the response due to the actinides

  13. Actinide and xenon reactivity effects in ATW high flux systems

    International Nuclear Information System (INIS)

    Woosley, M.; Olson, K.; Henderson, D. L.; Sailor, W. C.

    1995-01-01

    In this paper, initial system reactivity response to flux changes caused by the actinides and xenon are investigated separately for a high flux ATW system. The maximum change in reactivity after a flux change due to the effect of the changing quantities of actinides is generally at least two orders of magnitude smaller than either the positive or negative reactivity effect associated with xenon after a shutdown or start-up. In any transient flux event, the reactivity response of the system to xenon will generally occlude the response due to the actinides

  14. Actinide and Xenon reactivity effects in ATW high flux systems

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, M. [Univ. of Virginia, Charlottesville, VA (United States); Olson, K.; Henderson, D.L. [Univ. of Wisconsin, Madison, WI (United States)] [and others

    1995-10-01

    In this paper, initial system reactivity response to flux changes caused by the actinides and xenon are investigated separately for a high flux ATW system. The maximum change in reactivity after a flux change due to the effect of the changing quantities of actinides is generally at least two orders of magnitude smaller than either the positive or negative reactivity effect associated with xenon after a shutdown or start-up. In any transient flux event, the reactivity response of the system to xenon will generally occlude the response due to the actinides.

  15. Experimental and numerical investigation of the coolant mixing during fast deboration transients

    International Nuclear Information System (INIS)

    Hoehne, T.; Rohde, U.; Weiss, F.P.

    1999-01-01

    For the analysis of boron dilution transients and main steam line break scenarios the modeling of the coolant mixing inside the reactor vessel is important, because the reactivity insertion strongly depends on boron acid concentration or the coolant temperature distribution. Calculations for steady state flow conditions for the VVER-440 were performed with a CFD code (CFX-4). The comparison with experimental data and an analytical mixing model which is implemented in the neutron-kinetic code DYN3D showed a good agreement for near-nominal conditions. First experiments at the Rossendorf Mixing Test Facility ROCOM were performed simulating the start-up of the first main coolant pump. The reference reactor for the geometrically 1:5 scaled Plexiglas model is the German Konvoi type PWR. After demonstrating the capability of the CFD code to simulate these complicated flow transients, calculations were performed for the start-up of the first pump in a VVER-440 type reactor. These calculations are a first step of understanding the coolant mixing in the RPV of a VVER-440 type reactor under transient conditions. The results of the calculation show a very complex flow in the downcomer. A high downcomer of VVER-440 and the existence of the lower control rod chamber support coolant mixing is concluded. (author)

  16. Investigation of Natural Circulation Instability and Transients in Passively Safe Small Modular Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Mamoru [Purdue Univ., West Lafayette, IN (United State

    2016-11-30

    The NEUP funded project, NEUP-3496, aims to experimentally investigate two-phase natural circulation flow instability that could occur in Small Modular Reactors (SMRs), especially for natural circulation SMRs. The objective has been achieved by systematically performing tests to study the general natural circulation instability characteristics and the natural circulation behavior under start-up or design basis accident conditions. Experimental data sets highlighting the effect of void reactivity feedback as well as the effect of power ramp-up rate and system pressure have been used to develop a comprehensive stability map. The safety analysis code, RELAP5, has been used to evaluate experimental results and models. Improvements to the constitutive relations for flashing have been made in order to develop a reliable analysis tool. This research has been focusing on two generic SMR designs, i.e. a small modular Simplified Boiling Water Reactor (SBWR) like design and a small integral Pressurized Water Reactor (PWR) like design. A BWR-type natural circulation test facility was firstly built based on the three-level scaling analysis of the Purdue Novel Modular Reactor (NMR) with an electric output of 50 MWe, namely NMR-50, which represents a BWR-type SMR with a significantly reduced reactor pressure vessel (RPV) height. The experimental facility was installed with various equipment to measure thermalhydraulic parameters such as pressure, temperature, mass flow rate and void fraction. Characterization tests were performed before the startup transient tests and quasi-steady tests to determine the loop flow resistance. The control system and data acquisition system were programmed with LabVIEW to realize the realtime control and data storage. The thermal-hydraulic and nuclear coupled startup transients were performed to investigate the flow instabilities at low pressure and low power conditions for NMR-50. Two different power ramps were chosen to study the effect of startup

  17. PASP Plus Transient Pulse Monitor (TPM) - Data Analysis and Interpretation Report

    National Research Council Canada - National Science Library

    Adamo, Richard

    1996-01-01

    The Transient Pulse Monitor (TPM), part of the PASP Plus experiment aboard the APEX spacecraft, is designed to detect and characterize electromagnetic transient signals produced by electrostatic discharges on the solar array test modules...

  18. Transient waves in visco-elastic media

    CERN Document Server

    Ricker, Norman

    1977-01-01

    Developments in Solid Earth Geophysics 10: Transient Waves in Visco-Elastic Media deals with the propagation of transient elastic disturbances in visco-elastic media. More specifically, it explores the visco-elastic behavior of a medium, whether gaseous, liquid, or solid, for very-small-amplitude disturbances. This volume provides a historical overview of the theory of the propagation of elastic waves in solid bodies, along with seismic prospecting and the nature of seismograms. It also discusses the seismic experiments, the behavior of waves propagated in accordance with the Stokes wave

  19. Point kinetics improvements to evaluate three-dimensional effects in transients calculation

    International Nuclear Information System (INIS)

    Castellotti, U.

    1987-01-01

    A calculation method, which considers the flux axial perturbations in the parameters related to the reactivity within a point kinetics model, is described. The method considered uses axial factors of consideration which act on the thermohydraulic variables included in the reactivity calculation. The PUMA three-dimensional code as reference model for the comparisons, is used. The limitations inherent to the reactivity balance of the point models used in the transients calculation, are given. (Author)

  20. Results of LWR core transient benchmarks

    International Nuclear Information System (INIS)

    Finnemann, H.; Bauer, H.; Galati, A.; Martinelli, R.

    1993-10-01

    LWR core transient (LWRCT) benchmarks, based on well defined problems with a complete set of input data, are used to assess the discrepancies between three-dimensional space-time kinetics codes in transient calculations. The PWR problem chosen is the ejection of a control assembly from an initially critical core at hot zero power or at full power, each for three different geometrical configurations. The set of problems offers a variety of reactivity excursions which efficiently test the coupled neutronic/thermal - hydraulic models of the codes. The 63 sets of submitted solutions are analyzed by comparison with a nodal reference solution defined by using a finer spatial and temporal resolution than in standard calculations. The BWR problems considered are reactivity excursions caused by cold water injection and pressurization events. In the present paper, only the cold water injection event is discussed and evaluated in some detail. Lacking a reference solution the evaluation of the 8 sets of BWR contributions relies on a synthetic comparative discussion. The results of this first phase of LWRCT benchmark calculations are quite satisfactory, though there remain some unresolved issues. It is therefore concluded that even more challenging problems can be successfully tackled in a suggested second test phase. (authors). 46 figs., 21 tabs., 3 refs

  1. Quadratic reactivity fuel cycle model

    International Nuclear Information System (INIS)

    Lewins, J.D.

    1985-01-01

    For educational purposes it is highly desirable to provide simple yet realistic models for fuel cycle and fuel economy. In particular, a lumped model without recourse to detailed spatial calculations would be very helpful in providing the student with a proper understanding of the purposes of fuel cycle calculations. A teaching model for fuel cycle studies based on a lumped model assuming the summability of partial reactivities with a linear dependence of reactivity usefully illustrates fuel utilization concepts. The linear burnup model does not satisfactorily represent natural enrichment reactors. A better model, showing the trend of initial plutonium production before subsequent fuel burnup and fission product generation, is a quadratic fit. The study of M-batch cycles, reloading 1/Mth of the core at end of cycle, is now complicated by nonlinear equations. A complete account of the asymptotic cycle for any order of M-batch refueling can be given and compared with the linear model. A complete account of the transient cycle can be obtained readily in the two-batch model and this exact solution would be useful in verifying numerical marching models. It is convenient to treat the parabolic fit rho = 1 - tau 2 as a special case of the general quadratic fit rho = 1 - C/sub tau/ - (1 - C)tau 2 in suitably normalized reactivity and cycle time units. The parabolic results are given in this paper

  2. Description and characterization of the ACRR's programmable transient rod withdrawal mode

    International Nuclear Information System (INIS)

    Boldt, K.R.; Sullivan, W.H.; Kefauver, H.L.

    1980-01-01

    To satisfy experiment needs for Sandia's Advanced Reactor Safety Program, a programmable Transient Rod Withdrawal (TRW) mode has been developed for the Annular Core Research Reactor (ACRR). The programmable mode is a modification of the existing continuous-withdrawal TRW mode and permits speed and direction changes during the pulse sequence. Basically, a TRW operation is similar to a routine pulse operation except that transient rods are mechanically withdrawn rather than pneumatically fired. Being a pulse-type operation, the TRW mode complies with pulse-mode safety system settings. Control system interlocks prevent the pneumatic firing of rods in the TRW mode. The hardware for the programmable TRW mode includes three ACRR transient rods, the ACRR timer, two rod programmers, a minicomputer and a summing circuit for position indication. Each ACRR transient rod is mechanically driven by a stepping motor (rated torque at 4.24 joules) and is capable of a maximum TRW speed of 26.7 centimeters/ second. The maximum reactivity insertion rate is $2.45/second with a transient rod bank worth of $3.00 and $3.47/second with a bank worth of $4.25, which is expected to be installed soon. The ACRR timer is a multifunctional timer used in all operating modes of the reactor. In the programmable TRW mode, the timer starts the rod programmers and drops regulating rods to terminate the operation. Programmed withdrawal capability is provided by one of two rod programmers (a hardwire-based unit and a microprocessor-based unit). The hardwire unit has eight intervals in which speed, direction and distance are selected by switches on the front panel. The microprocessor-based unit has the capability of 64 intervals in which speed, direction, and distance or time can be specified. Programming this unit is accomplished from the front panel or by inputting data from an HP-9845. minicomputer via a digital I/O interface. Self-test programs in the software provide a continual check of an operating

  3. Transient osteoporosis of hip

    Directory of Open Access Journals (Sweden)

    Mahesh M Choudhary

    2015-01-01

    Full Text Available We report a case of transient osteoporosis of the hip (TOH in a 50-year-old man including the clinical presentation, diagnostic studies, management, and clinical progress. TOH is a rare self-limiting condition that typically affects middle-aged men or, less frequently, women in the third trimester of pregnancy. Affected individuals present clinically with acute hip pain, limping gait, and limited ranges of hip motion. TOH may begin spontaneously or after a minor trauma. Radiographs are typically unremarkable but magnetic resonance (MR imaging studies yield findings consistent with bone marrow edema. TOH is referred to as regional migratory osteoporosis (RMO if it travels to other joints or the contralateral hip. TOH often resembles osteonecrosis but the two conditions must be differentiated due to different prognoses and management approaches. The term TOH is often used interchangeably and synonymously with transient bone marrow edema (TBME.

  4. Transient response in granular bounded heap flows

    Science.gov (United States)

    Xiao, Hongyi; Ottino, Julio M.; Lueptow, Richard M.; Umbanhowar, Paul B.

    2017-11-01

    Heap formation, a canonical granular flow, is common in industry and is also found in nature. Here, we study the transition between steady flow states in quasi-2D bounded heaps by suddenly changing the feed rate from one fixed value to another. During the transition, in both experiments and discrete element method simulations, an additional wedge of flowing particles propagates over the rising free surface. The downstream edge of the wedge - the wedge front - moves downstream with velocity inversely proportional to the square root of time. An additional longer duration transient process continues after the wedge front reaches the downstream wall. The transient flux profile during the entire transition is well modeled by a diffusion-like equation derived from local mass balance and a local linear relation between the flux and the surface slope. Scalings for the transient kinematics during the flow transitions are developed based on the flux profiles. Funded by NSF Grant CBET-1511450.

  5. Stability of Ignition Transients

    OpenAIRE

    V.E. Zarko

    1991-01-01

    The problem of ignition stability arises in the case of the action of intense external heat stimuli when, resulting from the cut-off of solid substance heating, momentary ignition is followed by extinction. Physical pattern of solid propellant ignition is considered and ignition criteria available in the literature are discussed. It is shown that the above mentioned problem amounts to transient burning at a given arbitrary temperature distribution in the condensed phase. A brief survey...

  6. Transient FDTD simulation validation

    OpenAIRE

    Jauregui Tellería, Ricardo; Riu Costa, Pere Joan; Silva Martínez, Fernando

    2010-01-01

    In computational electromagnetic simulations, most validation methods have been developed until now to be used in the frequency domain. However, the EMC analysis of the systems in the frequency domain many times is not enough to evaluate the immunity of current communication devices. Based on several studies, in this paper we propose an alternative method of validation of the transients in time domain allowing a rapid and objective quantification of the simulations results.

  7. MHD aspects of coronal transients

    International Nuclear Information System (INIS)

    Anzer, U.

    1979-10-01

    If one defines coronal transients as events which occur in the solar corona on rapid time scales (< approx. several hours) then one would have to include a large variety of solar phenomena: flares, sprays, erupting prominences, X-ray transients, white light transients, etc. Here we shall focus our attention on the latter two phenomena. (orig.) 891 WL/orig. 892 RDG

  8. The impact of fuel temperature reactivity coefficient on loss of reactivity control accident

    International Nuclear Information System (INIS)

    Park, J. H.; Ryu, E. H.; Song, Y. M.; Jung, J. Y.

    2012-01-01

    Nuclear reactors experience small power fluctuations or anticipated operational transients during even normal power operation. During normal operation, the reactivity is mainly controlled by liquid zone controllers, adjuster rods, mechanical control absorbers, and moderator poison. Even when the reactor power is increased abruptly and largely from an accident and when reactor control systems cannot be actuated quickly due to a fast transient, the reactor should be controlled and stabilized by its inherent safety parameter, such as a negative PCR (Power Coefficient of Reactivity) feedback. A PWR (Pressurized Water Reactor), it is well designed for the reactor to have a negative PCR so that the reactor can be safely shut down or stabilized whenever an abrupt reactivity insertion into the reactor core occurs or the reactor power is abruptly increased. However, it is known that a CANDU reactor has a small amount of PCR, as either negative or positive, because of the different design basis and safety concepts from a PWR. CNSC's regulatory and safety regime has stated that; The PCR of CANDU reactors does not pose a significant risk. Consistent with Canadian nuclear safety requirements, nuclear power plants must have an appropriate combination of inherent and engineered safety features incorporated into the design of the reactor safety and control systems. A reactor design that has a PCR is quite acceptable provided that the reactor is stable against power fluctuations, and that the probability and consequences of any potential accidents that would be aggravated by a positive reactivity feedback are maintained within CNSCprescribed limits. Recently, it was issued licensing the refurbished Wolsong unit 1 in Korea to be operated continuously after its design lifetime in which the calculated PCR was shown to have a small positive value by applying the recent physics code systems, which are composed of WIMS IST, DRAGON IST, and RFSP IST. These code systems were transferred

  9. Void effects on BWR Doppler and void reactivity feedback

    International Nuclear Information System (INIS)

    Hsiang-Shou Cheng; Diamond, D.J.

    1978-01-01

    The significance of steam voids and control rods on the Doppler feedback in a gadolinia shimmed BWR is demonstrated. The importance of bypass voids when determining void feedback is also shown. Calculations were done using a point model, i.e., feedback was expressed in terms of reactivity coefficients which were determined for individual four-bundle configurations and then appropriately combined to yield reactor results. For overpower transients the inclusion of the void effect of control rods is to reduce Doppler feedback. For overpressurization transients the inclusion of the effect of bypass void wil increase the reactivity due to void collapse. (author)

  10. Experimental study and modelling of transient boiling

    International Nuclear Information System (INIS)

    Baudin, Nicolas

    2015-01-01

    A failure in the control system of the power of a nuclear reactor can lead to a Reactivity Initiated Accident in a nuclear power plant. Then, a power peak occurs in some fuel rods, high enough to lead to the coolant film boiling. It leads to an important increase of the temperature of the rod. The possible risk of the clad failure is a matter of interest for the Institut de Radioprotection et de Securite Nucleaire. The transient boiling heat transfer is not yet understood and modelled. An experimental set-up has been built at the Institut de Mecanique des Fluides de Toulouse (IMFT). Subcooled HFE-7000 flows vertically upward in a semi annulus test section. The inner half cylinder simulates the clad and is made of a stainless steel foil, heated by Joule effect. Its temperature is measured by an infrared camera, coupled with a high speed camera for the visualization of the flow topology. The whole boiling curve is studied in steady state and transient regimes: convection, onset of boiling, nucleate boiling, critical heat flux, film boiling and rewetting. The steady state heat transfers are well modelled by literature correlations. Models are suggested for the transient heat flux: the convection and nucleate boiling evolutions are self-similar during a power step. This observation allows to model more complex evolutions, as temperature ramps. The transient Hsu model well represents the onset of nucleate boiling. When the intensity of the power step increases, the film boiling begins at the same temperature but with an increasing heat flux. For power ramps, the critical heat flux decreases while the corresponding temperature increases with the heating rate. When the wall is heated, the film boiling heat transfer is higher than in steady state but it is not understood. A two-fluid model well simulates the cooling film boiling and the rewetting. (author)

  11. Reactive Kripke semantics

    CERN Document Server

    Gabbay, Dov M

    2013-01-01

    This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

  12. Magnetic transients in flares

    International Nuclear Information System (INIS)

    Zirin, H.; Tanaka, K.

    1981-01-01

    We present data on magnetic transients (mgtr's) observed in flares on 1980 July 1 and 5 with Big Bear videomagnetograph (VMG). The 1980 July 1 event was a white light flare in which a strong bipolar mgtr was observed, and a definite change in the sunspots occurred at the time of the flare. In the 1980 July 5 flare, a mgtr was observed in only one polarity, and, although no sunspot changes occurred simultaneous with the flare, major spot changes occurred in a period of hours

  13. Familial Transient Global Amnesia

    Directory of Open Access Journals (Sweden)

    R.Rhys Davies

    2012-12-01

    Full Text Available Following an episode of typical transient global amnesia (TGA, a female patient reported similar clinical attacks in 2 maternal aunts. Prior reports of familial TGA are few, and no previous account of affected relatives more distant than siblings or parents was discovered in a literature survey. The aetiology of familial TGA is unknown. A pathophysiological mechanism akin to that in migraine attacks, comorbidity reported in a number of the examples of familial TGA, is one possibility. The study of familial TGA cases might facilitate the understanding of TGA aetiology.

  14. Evaluating advanced LMR [liquid metal reactor] reactivity feedbacks using SSC

    International Nuclear Information System (INIS)

    Slovik, G.C.; Van Tuyle, G.J.; Kennett, R.J.; Cheng, H.S.

    1988-01-01

    Analyses of the PRISM and SAFR Liquid Metal Reactors with SSC are discussed from a safety and licensing perspective. The PRISM and SAFR reactors with metal fuel are designed for inherent shutdown responses to loss-of-flow and loss-of-heat-sink events. The demonstration of this technology was performed by EBR-II during experiments in April 1986 by ANL (Planchon, et al.). Response to postulated TOPs (control rod withdrawal) are made acceptable largely by reducing reactivity swings, and therefore minimizing the size of possible ractivity insertions. Analyses by DOE and the contractors GE, RI, and ANL take credit for several reactivity feedback mechanisms during transient calculations. These feedbacks include Doppler, sodium density, and thermal expansion of the grid plates, the load pads, the fuel (axial) and the control rod which are now factored into the BNL SSC analyses. The bowing feedback mechanism is not presently modeled in the SSC due to its complexity and subsequent large uncertainty. The analysis is conservative by not taking credit for this negative feedback mechanism. Comparisons of BNL predictions with DOE contractors are provided

  15. Inherent safety that the reactivity effect of core bending in fast reactors brings about

    International Nuclear Information System (INIS)

    Nakagawa, Masatoshi; Yagawa, Genki.

    1994-01-01

    FBRs have the merit on safety by low operation pressure and the large heat capacity of coolant, in addition, due to the core temperature rise at the time of accidents and the thermal expansion of core structures, the negative feedback of reactivity can be expected. Recently, attention has been paid to the negative feedback of reactivity due to core bending. It can be expected also in the core of limited free bow type. Bending is caused by the difference of thermal expansion on six surfaces of hexagonal wrapper tubes. The bending changes core reactivity and exerts effects to fuel exchange force and operation, insertion of control rods and the structural soundness of fuel assemblies. for the purpose of limiting the effect that core bending exerts to core characteristics to allowable range, core constraint mechanism is installed. The behavior of core bending at the time of anticipated transient without scram is explained. The example of the analysis of PRISM reactor is shown. The experiment that confirmed the negative feedback of reactivity due to core bending under the condition of ULOF was that at the fast flux test facility. (K.I.)

  16. Reactive sites influence in PMMA oligomers reactivity: a DFT study

    Science.gov (United States)

    Paz, C. V.; Vásquez, S. R.; Flores, N.; García, L.; Rico, J. L.

    2018-01-01

    In this work, we present a theoretical study of methyl methacrylate (MMA) living anionic polymerization. The study was addressed to understanding two important experimental observations made for Michael Szwarc in 1956. The unexpected effect of reactive sites concentration in the propagation rate, and the self-killer behavior of MMA (deactivating of living anionic polymerization). The theoretical calculations were performed by density functional theory (DFT) to obtain the frontier molecular orbitals values. These values were used to calculate and analyze the chemical interaction descriptors in DFT-Koopmans’ theorem. As a result, it was observed that the longest chain-length species (related with low concentration of reactive sites) exhibit the highest reactivity (behavior associated with the increase of the propagation rate). The improvement in this reactivity was attributed to the crosslinking produced in the polymethyl methacrylate chains. Meanwhile, the self-killer behavior was associated with the intermolecular forces present in the reactive sites. This behavior was associated to an obstruction in solvation, since the active sites remained active through all propagation species. The theoretical results were in good agreement with the Szwarc experiments.

  17. A fast reactor transient analysis methodology for personal computers

    International Nuclear Information System (INIS)

    Ott, K.O.

    1993-01-01

    A simplified model for a liquid-metal-cooled reactor (LMR) transient analysis, in which point kinetics as well as lumped descriptions of the heat transfer equations in all components are applied, is converted from a differential into an integral formulation. All 30 differential balance equations are implicitly solved in terms of convolution integrals. The prompt jump approximation is applied as the strong negative feedback effectively keeps the net reactivity well below prompt critical. After implicit finite differencing of the convolution integrals, the kinetics equation assumes a new form, i.e., the quadratic dynamics equation. In this integral formulation, the initial value problem of typical LMR transients can be solved with large item steps (initially 1 s, later up to 256 s). This then makes transient problems amenable to a treatment on personal computer. The resulting mathematical model forms the basis for the GW-BASIC program LMR transient calculation (LTC) program. The LTC program has also been converted to QuickBASIC. The running time for a 10-h transient overpower transient is then ∼40 to 10 s, depending on the hardware version (286, 386, or 486 with math coprocessors)

  18. Visual investigation of transient fuel behavior under a rapid heating condition

    International Nuclear Information System (INIS)

    Saito, Shinzo

    1981-10-01

    An in-reactor experimental research on fuel behavior under reactivity initiated accident (RIA) conditions is being conducted in the Nuclear Safety Research Reactor (NSRR). The optical system in which a non-browning lens periscope is directly installed in the test section was successfully developed for photographing transient fuel behavior. Several phenomena which had never been revealed before were observed in the slow motion pictures taken in the NSRR experiments which were performed in the water and air environments. As for incipient failure mechanism for an unirradiated fuel rod under RIA conditions, brittle fracture of the cladding during quenching is dominant. However, a split cracking possibly occurs during even red hot state of the cladding. It is considered that the crack is generated by the local internal pressure increase at the specified region blocked up due to the melting of the cladding inner surface. The film boiling is unexpectablly violent specially in the early stage of the transient, and film thickness becomes 5 -- 6 mm at maximum. The observed thick vapor film can not be explained by the conventional theory, but the effect of hydrogen which is produced by Zircaloy-water reaction is reasonably explained to form thick film in the report. The molten fuel was expelled from the cladding in the experiment which was performed in an air environment. The expelled fuel fragmented due to possibly initial motion effect, not mechanical collision effect, because Weber number is smaller than the critical value. (author)

  19. Measurand transient signal suppressor

    Science.gov (United States)

    Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    A transient signal suppressor for use in a controls system which is adapted to respond to a change in a physical parameter whenever it crosses a predetermined threshold value in a selected direction of increasing or decreasing values with respect to the threshold value and is sustained for a selected discrete time interval is presented. The suppressor includes a sensor transducer for sensing the physical parameter and generating an electrical input signal whenever the sensed physical parameter crosses the threshold level in the selected direction. A manually operated switch is provided for adapting the suppressor to produce an output drive signal whenever the physical parameter crosses the threshold value in the selected direction of increasing or decreasing values. A time delay circuit is selectively adjustable for suppressing the transducer input signal for a preselected one of a plurality of available discrete suppression time and producing an output signal only if the input signal is sustained for a time greater than the selected suppression time. An electronic gate is coupled to receive the transducer input signal and the timer output signal and produce an output drive signal for energizing a control relay whenever the transducer input is a non-transient signal which is sustained beyond the selected time interval.

  20. Transient regional osteoporosis

    Directory of Open Access Journals (Sweden)

    F. Trotta

    2011-09-01

    Full Text Available Transient osteoporosis of the hip and regional migratory osteoporosis are uncommon and probably underdiagnosed bone diseases characterized by pain and functional limitation mainly affecting weight-bearing joints of the lower limbs. These conditions are usually self-limiting and symptoms tend to abate within a few months without sequelae. Routine laboratory investigations are unremarkable. Middle aged men and women during the last months of pregnancy or in the immediate post-partum period are principally affected. Osteopenia with preservation of articular space and transitory edema of the bone marrow provided by magnetic resonance imaging are common to these two conditions, so they are also known by the term regional transitory osteoporosis. The appearance of bone marrow edema is not specific to regional transitory osteoporosis but can be observed in several diseases, i.e. trauma, reflex sympathetic dystrophy, avascular osteonecrosis, infections, tumors from which it must be differentiated. The etiology of this condition is unknown. Pathogenesis is still debated in particular the relationship with reflex sympathetic dystrophy, with which regional transitory osteoporosis is often identified. The purpose of the present review is to remark on the relationship between transient osteoporosis of the hip and regional migratory osteoporosis with particular attention to the bone marrow edema pattern and relative differential diagnosis.

  1. Acetazolamide-augmented dynamic BOLD (aczBOLD imaging for assessing cerebrovascular reactivity in chronic steno-occlusive disease of the anterior circulation: An initial experience

    Directory of Open Access Journals (Sweden)

    Junjie Wu

    2017-01-01

    Full Text Available The purpose of this study was to measure cerebrovascular reactivity (CVR in chronic steno-occlusive disease using a novel approach that couples BOLD imaging with acetazolamide (ACZ vasoreactivity (aczBOLD, to evaluate dynamic effects of ACZ on BOLD and to establish the relationship between aczBOLD and dynamic susceptibility contrast (DSC perfusion MRI. Eighteen patients with unilateral chronic steno-occlusive disease of the anterior circulation underwent a 20-min aczBOLD imaging protocol, with ACZ infusion starting at 5 min of scan initiation. AczBOLD reactivity was calculated on a voxel-by-voxel basis to generate CVR maps for subsequent quantitative analyses. Reduced CVR was observed in the diseased vs. the normal hemisphere both by qualitative and quantitative assessment (gray matter (GM: 4.13% ± 1.16% vs. 4.90% ± 0.98%, P = 0.002; white matter (WM: 2.83% ± 1.23% vs. 3.50% ± 0.94%, P = 0.005. In all cases BOLD signal began increasing immediately following ACZ infusion, approaching a plateau at ~8.5 min after infusion, with the tissue volume of reduced augmentation increasing progressively with time, peaking at 2.60 min (time range above 95% of the maximum value: 0–4.43 min for the GM and 1.80 min (time range above 95% of the maximum value: 1.40–3.53 min for the WM. In the diseased hemisphere, aczBOLD CVR significantly correlated with baseline DSC time-to-maximum of the residue function (Tmax (P = 0.008 for the WM and normalized cerebral blood flow (P = 0.003 for the GM, and P = 0.001 for the WM. AczBOLD provides a novel, safe, easily implementable approach to CVR measurement in the routine clinical environments. Further studies can establish quantitative thresholds from aczBOLD towards identification of patients at heightened risk of recurrent ischemia and cognitive decline.

  2. Reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Yadav Mukesh

    2009-01-01

    Full Text Available Reactive perforating collagenosis is a rare cutaneous disorder of unknown etiology. We hereby describe a case of acquired reactive perforating collagenosis in a patient of diabetes and chronic renal failure.

  3. Preliminary analysis of typical transients in fusion driven subcritical system (FDS-I)

    International Nuclear Information System (INIS)

    Bai Yunqing; Ke Yan; Wu Yican

    2007-01-01

    The potential safety characteristic is expected as one of the advantages of fusion-driven subcritical system (FDS-I) for the transmutation and incineration of nuclear waste compared with the critical reactor. Transients of the FDS-I may occur due to the perturbation of external neutron source, the failure of functional device, and the occurrence of the uncontrolled event. As typical transient scenarios, the following cases were analyzed: unprotected plasma overpower (UPOP), unprotected loss of flow (ULOF), unprotected transient overpower (UTOP). The transient analyses for the FDS-I were performed with a coupled two-dimensional thermal-hydraulics and neutronics transient analysis code NTC2D. The negative feedback of reactivity is the interesting safety feature of FDS-I as temperature increase, due to the fuel form of the circulating particle. The present simulation results showed that the current FDS-I design has a resistance against severe transient scenarios. (author)

  4. Reactivity on the Web

    OpenAIRE

    Bailey, James; Bry, François; Eckert, Michael; Patrânjan, Paula Lavinia

    2005-01-01

    Reactivity, the ability to detect simple and composite events and respond in a timely manner, is an essential requirement in many present-day information systems. With the emergence of new, dynamic Web applications, reactivity on the Web is receiving increasing attention. Reactive Web-based systems need to detect and react not only to simple events but also to complex, real-life situations. This paper introduces XChange, a language for programming reactive behaviour on the Web,...

  5. Monadic Functional Reactive Programming

    NARCIS (Netherlands)

    A.J. van der Ploeg (Atze); C Shan

    2013-01-01

    htmlabstractFunctional Reactive Programming (FRP) is a way to program reactive systems in functional style, eliminating many of the problems that arise from imperative techniques. In this paper, we present an alternative FRP formulation that is based on the notion of a reactive computation: a

  6. The joy of transient chaos

    Energy Technology Data Exchange (ETDEWEB)

    Tél, Tamás [Institute for Theoretical Physics, Eötvös University, and MTA-ELTE Theoretical Physics Research Group, Pázmány P. s. 1/A, Budapest H-1117 (Hungary)

    2015-09-15

    We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

  7. Transient osteoporosis of the hip

    International Nuclear Information System (INIS)

    McWalter, Patricia; Hassan Ahmed

    2007-01-01

    Transient osteoporosis of the hip is an uncommon cause of hip pain, mostly affecting healthy middle-aged men and also women in the third trimester of pregnancy. We present a case of transient osteoporosis of the hip in a 33-year-old non-pregnant female patient. This case highlights the importance of considering a diagnosis of transient osteoporosis of the hip in patients who present with hip pain. (author)

  8. The ZTF Bright Transient Survey

    Science.gov (United States)

    Fremling, C.; Sharma, Y.; Kulkarni, S. R.; Miller, A. A.; Taggart, K.; Perley, D. A.; Gooba, A.

    2018-06-01

    As a supplement to the Zwicky Transient Facility (ZTF; ATel #11266) public alerts (ATel #11685) we plan to report (following ATel #11615) bright probable supernovae identified in the raw alert stream from the ZTF Northern Sky Survey ("Celestial Cinematography"; see Bellm & Kulkarni, 2017, Nature Astronomy 1, 71) to the Transient Name Server (https://wis-tns.weizmann.ac.il) on a daily basis; the ZTF Bright Transient Survey (BTS; see Kulkarni et al., 2018; arXiv:1710.04223).

  9. The joy of transient chaos.

    Science.gov (United States)

    Tél, Tamás

    2015-09-01

    We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

  10. Transient Infrared Emission Spectroscopy

    Science.gov (United States)

    Jones, Roger W.; McClelland, John F.

    1989-12-01

    Transient Infrared Emission Spectroscopy (TIRES) is a new technique that reduces the occurrence of self-absorption in optically thick solid samples so that analytically useful emission spectra may be observed. Conventional emission spectroscopy, in which the sample is held at an elevated, uniform temperature, is practical only for optically thin samples. In thick samples the emission from deep layers of the material is partially absorbed by overlying layers.1 This self-absorption results in emission spectra from most optically thick samples that closely resemble black-body spectra. The characteristic discrete emission bands are severely truncated and altered in shape. TIRES bypasses this difficulty by using a laser to heat only an optically thin surface layer. The increased temperature of the layer is transient since the layer will rapidly cool and thicken by thermal diffusion; hence the emission collection must be correlated with the laser heating. TIRES may be done with both pulsed and cw lasers.2,3 When a pulsed laser is used, the spectrometer sampling must be synchronized with the laser pulsing so that only emission during and immediately after each laser pulse is observed.3 If a cw laser is used, the sample must move rapidly through the beam. The hot, transient layer is then in the beam track on the sample at and immediately behind the beam position, so the spectrometer field of view must be limited to this region near the beam position.2 How much self-absorption the observed emission suffers depends on how thick the heated layer has grown by thermal diffusion when the spectrometer samples the emission. Use of a pulsed laser synchronized with the spectrometer sampling readily permits reduction of the time available for heat diffusion to about 100 acs .3 When a cw laser is used, the heat-diffusion time is controlled by how small the spectrometer field of view is and by how rapidly the sample moves past within this field. Both a very small field of view and a

  11. Anticipated transients without scram

    International Nuclear Information System (INIS)

    Lellouche, G.S.

    1980-01-01

    This article discusses in various degrees of depth the publications WASH-1270, WASH-1400, and NUREG-0460, and has as its purpose a description of the technical work done by Electric Power Research Institute (EPRI) personnel and its contractors on the subject of anticipated transients without scram (ATWS). It demonstrates the close relation between the probability of scram failure derived from historical scram data and that derived from the use of component data in a model of a system (the so-called synthesis method), such as was done in WASH-1400. The inherent conservatism of these models is demonstrated by showing that they predict significantly more events than have in fact occurred and that such models still predict scram failure probabilities low enough to make ATWS an insignificant contributor to accident risk

  12. Transient fuel melting

    International Nuclear Information System (INIS)

    Roche, L.; Schmitz, F.

    1982-10-01

    The observation of micrographic documents from fuel after a CABRI test leads to postulate a specific mode of transient fuel melting during a rapid nuclear power excursion. When reaching the melt threshold, the bands which are characteristic for the solid state are broken statistically over a macroscopic region. The time of maintaining the fuel at the critical enthalpy level between solid and liquid is too short to lead to a phase separation. A significant life-time (approximately 1 second) of this intermediate ''unsolide'' state would have consequences on the variation of physical properties linked to the phase transition solid/liquid: viscosity, specific volume and (for the irradiated fuel) fission gas release [fr

  13. Transient osteoporosis of pregnancy.

    Science.gov (United States)

    Maliha, George; Morgan, Jordan; Vrahas, Mark

    2012-08-01

    Transient osteoporosis of pregnancy (TOP) is a rare yet perhaps under-reported condition that has affected otherwise healthy pregnancies throughout the world. The condition presents suddenly in the third trimester of a usually uneventful pregnancy and progressively immobilizes the mother. Radiographic studies detect drastic loss of bone mass, elevated rates of turnover in the bone, and oedema in the affected portion. Weakness of the bone can lead to fractures during delivery and other complications for the mother. Then, within weeks of labour, symptoms and radiological findings resolve. Aetiology is currently unknown, although neural, vascular, haematological, endocrine, nutrient-deficiency, and other etiologies have been proposed. Several treatments have also been explored, including simple bed rest, steroids, bisphosphonates, calcitonin, induced termination of pregnancy, and surgical intervention. The orthopedist plays an essential role in monitoring the condition (and potential complications) as well as ensuring satisfactory outcomes for both the mother and newborn. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Code Coupling for Multi-Dimensional Core Transient Analysis

    International Nuclear Information System (INIS)

    Park, Jin-Woo; Park, Guen-Tae; Park, Min-Ho; Ryu, Seok-Hee; Um, Kil-Sup; Lee Jae-Il

    2015-01-01

    After the CEA ejection, the nuclear power of the reactor dramatically increases in an exponential behavior until the Doppler effect becomes important and turns the reactivity balance and power down to lower levels. Although this happens in a very short period of time, only few seconds, the energy generated can be very significant and cause fuel failures. The current safety analysis methodology which is based on overly conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KEPCO Nuclear Fuel(KNF) is developing the multi-dimensional safety analysis methodology to mitigate the consequences of the single CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST, which have transient calculation performance, were coupled using message passing interface (MPI). This paper presents the methodology used for code coupling and the preliminary simulation results with the coupled code system (CHASER). Multi-dimensional core transient analysis code system, CHASER, has been developed and it was applied to simulate a single CEA ejection accident. CHASER gave a good prediction of multi-dimensional core transient behaviors during transient. In the near future, the multi-dimension CEA ejection analysis methodology using CHASER is planning to be developed. CHASER is expected to be a useful tool to gain safety margin for reactivity initiated accidents (RIAs), such as a single CEA ejection accident

  15. Code Coupling for Multi-Dimensional Core Transient Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jin-Woo; Park, Guen-Tae; Park, Min-Ho; Ryu, Seok-Hee; Um, Kil-Sup; Lee Jae-Il [KEPCO NF, Daejeon (Korea, Republic of)

    2015-05-15

    After the CEA ejection, the nuclear power of the reactor dramatically increases in an exponential behavior until the Doppler effect becomes important and turns the reactivity balance and power down to lower levels. Although this happens in a very short period of time, only few seconds, the energy generated can be very significant and cause fuel failures. The current safety analysis methodology which is based on overly conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KEPCO Nuclear Fuel(KNF) is developing the multi-dimensional safety analysis methodology to mitigate the consequences of the single CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST, which have transient calculation performance, were coupled using message passing interface (MPI). This paper presents the methodology used for code coupling and the preliminary simulation results with the coupled code system (CHASER). Multi-dimensional core transient analysis code system, CHASER, has been developed and it was applied to simulate a single CEA ejection accident. CHASER gave a good prediction of multi-dimensional core transient behaviors during transient. In the near future, the multi-dimension CEA ejection analysis methodology using CHASER is planning to be developed. CHASER is expected to be a useful tool to gain safety margin for reactivity initiated accidents (RIAs), such as a single CEA ejection accident.

  16. Use of a computerized C-reactive protein (CRP based sepsis evaluation in very low birth weight (VLBW infants: a five-year experience.

    Directory of Open Access Journals (Sweden)

    Sarah A Coggins

    Full Text Available Serial C-reactive protein (CRP values may be useful for decision-making regarding duration of antibiotics in neonates. However, established standard of practice for its use in preterm very low birth weight (<1500 g, VLBW infants are lacking.Evaluate compliance with a CRP-guided computerized decision support (CDS algorithm and compare characteristics and outcomes of compliant versus non-compliant cases. Measure correlation between CRPs and white blood count (WBC indices.We examined 3 populations: 1 all preterm VLBW infants born at Vanderbilt 2006-2011 - we assessed provider compliance with CDS algorithm and measured relevant outcomes; 2 all patients with positive blood culture results admitted to the Vanderbilt NICU 2006-2012 - we tested the correlation between CRP and WBC results within 7 days of blood culture phlebotomy; 3 1,000 randomly selected patients out of the 7,062 patients admitted to the NICU 2006-2012 - we correlated time-associated CRP values and absolute neutrophil counts.Of 636 VLBW infants in cohort 1, 569 (89% received empiric antibiotics for suspected early-onset sepsis. In 409 infants (72% the CDS algorithm was followed; antibiotics were discontinued ≤48 hours in 311 (55% with normal serial CRPs and continued in 98 (17% with positive CRPs, resulting in significant reduction in antibiotic exposure (p<0.001 without increase in complications or subsequent infections. One hundred sixty (28% were considered non-compliant because antibiotics were continued beyond 48 hours despite negative serial CRPs and blood cultures. Serial CRPs remained negative in 38 (12% of 308 blood culture-positive infants from cohort 2, but only 4 patients had clinically probable sepsis with single organisms and no immunodeficiency besides extreme prematurity. Leukopenia of any cell type was not linked with CRPs in cohorts 2 and 3.CDS/CRP-guided antibiotic use is safe and effective in culture-negative VLBW infants. CRP results are not affected by low WBC

  17. Digital reactivity meter

    International Nuclear Information System (INIS)

    Akkus, B.; Anac, H.; Alsan, S.; Erk, S.

    1991-01-01

    Nowadays, various digital methods making use of microcomputers for neutron detector signals and determining the reactivity by numerical calculations are used in reactor control systems in place of classical reactivity meters. In this work, a calculation based on the ''The Time Dependent Transport Equation'' has been developed for determining the reactivity numerically. The reactivity values have been obtained utilizing a computer-based data acquisition and control system and compared with the analog reactivity meter values as well as the values calculated from the ''Inhour Equation''

  18. Transients in reactors for power systems compensation

    Science.gov (United States)

    Abdul Hamid, Haziah

    This thesis describes new models and investigations into switching transient phenomena related to the shunt reactors and the Mechanically Switched Capacitor with Damping Network (MSCDN) operations used for reactive power control in the transmission system. Shunt reactors and MSCDN are similar in that they have reactors. A shunt reactor is connected parallel to the compensated lines to absorb the leading current, whereas the MSCDN is a version of a capacitor bank designed as a C-type filter for use in the harmonic-rich environment. In this work, models have been developed and transient overvoltages due to shunt reactor deenergisation were estimated analytically using MathCad, a mathematical program. Computer simulations used the ATP/EMTP program to reproduce both single-phase and three-phase shunt reactor switching at 275 kV operational substations. The effect of the reactor switching on the circuit breaker grading capacitor was also examined by considering various switching conditions.. The main original achievement of this thesis is the clarification of failure mechanisms occurring in the air-core filter reactor due to MSCDN switching operations. The simulation of the MSCDN energisation was conducted using the ATP/EMTP program in the presence of surge arresters. The outcome of this simulation shows that extremely fast transients were established across the air-core filter reactor. This identified transient event has led to the development of a detailed air-core reactor model, which accounts for the inter-turn RLC parameters as well as the stray capacitances-to-ground. These parameters are incorporated into the transient simulation circuit, from which the current and voltage distribution across the winding were derived using electric field and equivalent circuit modelling. Analysis of the results has revealed that there are substantial dielectric stresses imposed on the winding insulation that can be attributed to a combination of three factors. (i) First, the

  19. SCANAIR: A transient fuel performance code

    International Nuclear Information System (INIS)

    Moal, Alain; Georgenthum, Vincent; Marchand, Olivier

    2014-01-01

    Highlights: • Since the early 1990s, the code SCANAIR is developed at IRSN. • The software focuses on studying fast transients such as RIA in light water reactors. • The fuel rod modelling is based on a 1.5D approach. • Thermal and thermal-hydraulics, mechanical and gas behaviour resolutions are coupled. • The code is used for safety assessment and integral tests analysis. - Abstract: Since the early 1990s, the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN) has developed the SCANAIR computer code with the view to analysing pressurised water reactor (PWR) safety. This software specifically focuses on studying fast transients such as reactivity-initiated accidents (RIA) caused by possible ejection of control rods. The code aims at improving the global understanding of the physical mechanisms governing the thermal-mechanical behaviour of a single rod. It is currently used to analyse integral tests performed in CABRI and NSRR experimental reactors. The resulting validated code is used to carry out studies required to evaluate margins in relation to criteria for different types of fuel rods used in nuclear power plants. Because phenomena occurring during fast power transients are complex, the simulation in SCANAIR is based on a close coupling between several modules aimed at modelling thermal, thermal-hydraulics, mechanical and gas behaviour. During the first stage of fast power transients, clad deformation is mainly governed by the pellet–clad mechanical interaction (PCMI). At the later stage, heat transfers from pellet to clad bring the cladding material to such high temperatures that the boiling crisis might occurs. The significant over-pressurisation of the rod and the fact of maintaining the cladding material at elevated temperatures during a fairly long period can lead to ballooning and possible clad failure. A brief introduction describes the context, the historical background and recalls the main phenomena involved under

  20. SCANAIR: A transient fuel performance code

    Energy Technology Data Exchange (ETDEWEB)

    Moal, Alain, E-mail: alain.moal@irsn.fr; Georgenthum, Vincent; Marchand, Olivier

    2014-12-15

    Highlights: • Since the early 1990s, the code SCANAIR is developed at IRSN. • The software focuses on studying fast transients such as RIA in light water reactors. • The fuel rod modelling is based on a 1.5D approach. • Thermal and thermal-hydraulics, mechanical and gas behaviour resolutions are coupled. • The code is used for safety assessment and integral tests analysis. - Abstract: Since the early 1990s, the French “Institut de Radioprotection et de Sûreté Nucléaire” (IRSN) has developed the SCANAIR computer code with the view to analysing pressurised water reactor (PWR) safety. This software specifically focuses on studying fast transients such as reactivity-initiated accidents (RIA) caused by possible ejection of control rods. The code aims at improving the global understanding of the physical mechanisms governing the thermal-mechanical behaviour of a single rod. It is currently used to analyse integral tests performed in CABRI and NSRR experimental reactors. The resulting validated code is used to carry out studies required to evaluate margins in relation to criteria for different types of fuel rods used in nuclear power plants. Because phenomena occurring during fast power transients are complex, the simulation in SCANAIR is based on a close coupling between several modules aimed at modelling thermal, thermal-hydraulics, mechanical and gas behaviour. During the first stage of fast power transients, clad deformation is mainly governed by the pellet–clad mechanical interaction (PCMI). At the later stage, heat transfers from pellet to clad bring the cladding material to such high temperatures that the boiling crisis might occurs. The significant over-pressurisation of the rod and the fact of maintaining the cladding material at elevated temperatures during a fairly long period can lead to ballooning and possible clad failure. A brief introduction describes the context, the historical background and recalls the main phenomena involved under

  1. Method of controlling reactivity

    International Nuclear Information System (INIS)

    Tochihara, Hiroshi.

    1982-01-01

    Purpose: To improve the reactivity controlling characteristics by artificially controlling the leakage of neutron from a reactor and providing a controller for controlling the reactivity. Method: A reactor core is divided into several water gaps to increase the leakage of neutron, its reactivity is reduced, a gas-filled control rod or a fuel assembly is inserted into the gap as required, the entire core is coupled in a system to reduce the leakage of the neutron, and the reactivity is increased. The reactor shutdown is conducted by the conventional control rod, and to maintain critical state, boron density varying system is used together. Futher, a control rod drive is used with that similar to the conventional one, thereby enabling fast reactivity variation, and the positive reactivity can be obtained by the insertion, thereby improving the reactivity controlling characteristics. (Yoshihara, H.)

  2. Irradiation creep transients in Ni-4 at.% Si

    International Nuclear Information System (INIS)

    Nagakawa, J.

    1983-01-01

    In the course of irradiation creep experiments on Ni-4 at.% Si alloy, two types of creep transients were observed on the termination of irradiation. The short term transient was completed within one minute while the long term transient persisted for nearly ten hours. A change in the temperature distribution was excluded from the possible causes, partly because the stress dependence of the observed transient strains was not linear, and partly because the strain increase expected from the temperature change was much smaller than the observed value. Transient behavior of point defects was examined in conjunction with the climb-glide mechanism and the steady-state irradiation creep data. Calculated creep transient due to excess vacancy flux to dislocations was in good agreement with the observed short term transient. The long term transient appears to be a result of dislocation microstructure change. The present results suggest an enhanced irradiation creep under cyclic irradiation conditions which will be encountered in the early generations of fusion reactors. (orig.)

  3. Instructions for applying inverse method for reactivity measurement

    International Nuclear Information System (INIS)

    Milosevic, M.

    1988-11-01

    This report is a brief description of the completed method for reactivity measurement. It contains description of the experimental procedure needed instrumentation and computer code IM for determining reactivity. The objective of this instructions manual is to enable experiments and reactivity measurement on any critical system according to the methods adopted at the RB reactor

  4. Modelling and transient simulation of water flow in pipelines using WANDA Transient software

    Directory of Open Access Journals (Sweden)

    P.U. Akpan

    2017-09-01

    Full Text Available Pressure transients in conduits such as pipelines are unsteady flow conditions caused by a sudden change in the flow velocity. These conditions might cause damage to the pipelines and its fittings if the extreme pressure (high or low is experienced within the pipeline. In order to avoid this occurrence, engineers usually carry out pressure transient analysis in the hydraulic design phase of pipeline network systems. Modelling and simulation of transients in pipelines is an acceptable and cost effective method of assessing this problem and finding technical solutions. This research predicts the pressure surge for different flow conditions in two different pipeline systems using WANDA Transient simulation software. Computer models were set-up in WANDA Transient for two different systems namely; the Graze experiment (miniature system and a simple main water riser system based on some initial laboratory data and system parameters. The initial laboratory data and system parameters were used for all the simulations. Results obtained from the computer model simulations compared favourably with the experimental results at Polytropic index of 1.2.

  5. Analysis of reactivity feedback effects of void and temperature in the MAPLE-X10 reactor

    International Nuclear Information System (INIS)

    Carlson, P.A.; Heeds, W.; Shim, S.Y.; King, S.G.

    1992-07-01

    The methods used for evaluating the void and temperature reactivity coefficients for the MAPLE-X10 Reactor are described and factors used in estimating their accuracy are discussed. The report presents representative transient analysis results using the CATHENA thermalhydraulics code. The role of the reactivity coefficients and their precision is discussed. The results are reviewed in terms of their safety implications

  6. Various reactivity effects value for assuring fast reactor core inherent safety

    International Nuclear Information System (INIS)

    Belov, S.B.; Vasilyev, B.A.

    1991-01-01

    The paper presents the results of temperature and power reactivity feedback components calculations for fast reactors with different core volume when using oxide, carbide, nitride and metal fuel. Reactor parameters change in loss of flow without scram and transient over power without scram accidents was evaluated. The importance of various reactivity feedback components in restricting the consequences of these accidents has been analyzed. (author)

  7. Pressure transients in pipeline systems

    DEFF Research Database (Denmark)

    Voigt, Kristian

    1998-01-01

    This text is to give an overview of the necessary background to do investigation of pressure transients via simulations. It will describe briefly the Method of Characteristics which is the defacto standard for simulating pressure transients. Much of the text has been adopted from the book Pressur...

  8. Fuel-pin cladding transient failure strain criterion

    International Nuclear Information System (INIS)

    Bard, F.E.; Duncan, D.R.; Hunter, C.W.

    1983-01-01

    A criterion for cladding failure based on accumulated strain was developed for mixed uranium-plutonium oxide fuel pins and used to interpret the calculated strain results from failed transient fuel pin experiments conducted in the Transient Reactor Test (TREAT) facility. The new STRAIN criterion replaced a stress-based criterion that depends on the DORN parameter and that incorrectly predicted fuel pin failure for transient tested fuel pins. This paper describes the STRAIN criterion and compares its prediction with those of the stress-based criterion

  9. Development of an alternative reactivity meter for nuclear reactor control

    International Nuclear Information System (INIS)

    Ferreira, P.S.B.

    1991-01-01

    This work describes an alternative version of the IPEN-CNEN/SP reactivity-meter. This new version utilizes a programmable electrometer (to realize the data acquisition) and a IBM-PC microcomputer to process the reactivity calculation. The aim of development of this alternative reactivity-meter is to have available a equipment of measurements of reactivity in the case of the later version show any problem during an experiment. (author)

  10. Investigation of natural circulation instability and transients in passively safe novel modular reactor

    Science.gov (United States)

    Shi, Shanbin

    The Purdue Novel Modular Reactor (NMR) is a new type small modular reactor (SMR) that belongs to the design of boiling water reactor (BWR). Specifically, the NMR is one third the height and area of a conventional BWR reactor pressure vessel (RPV) with an electric output of 50 MWe. The fuel cycle length of the NMR-50 is extended up to 10 years due to optimized neutronics design. The NMR-50 is designed with double passive engineering safety system. However, natural circulation BWRs (NCBWR) could experience certain operational difficulties due to flow instabilities that occur at low pressure and low power conditions. Static instabilities (i.e. flow excursion (Ledinegg) instability and flow pattern transition instability) and dynamic instabilities (i.e. density wave instability and flashing/condensation instability) pose a significant challenge in two-phase natural circulation systems. In order to experimentally study the natural circulation flow instability, a proper scaling methodology is needed to build a reduced-size test facility. The scaling analysis of the NMR uses a three-level scaling method, which was developed and applied for the design of the Purdue Multi-dimensional Integral Test Assembly (PUMA). Scaling criteria is derived from dimensionless field equations and constitutive equations. The scaling process is validated by the RELAP5 analysis for both steady state and startup transients. A new well-scaled natural circulation test facility is designed and constructed based on the scaling analysis of the NMR-50. The experimental facility is installed with different equipment to measure various thermal-hydraulic parameters such as pressure, temperature, mass flow rate and void fraction. Characterization tests are performed before the startup transient tests and quasi-steady tests to determine the loop flow resistance. The controlling system and data acquisition system are programmed with LabVIEW to realize the real-time control and data storage. The thermal

  11. Transient Analysis of Generation IV quick reactors; Analisis de Transitorios en Reactores Rapidos de Generacion IV

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, M.; Martin-Fuertes, F.

    2013-07-01

    As a complement to the attached code 3D neutron-CIEMAT thermohydraulic added a module to simulate transient. Temporary kinetics is resolved by factoring flow in a spatial part and another storm. MCNP provides the reactivity and updated spatial function and COBRA-IV calculates the temperature distribution. Temporary dependence of amplitude is calculated using time delayed neutron Kinetic equations. As an example of application, examines a transient loss of flow in MYRRHA, a lead-cooled experimental reactor.

  12. Development of a computer code for Dalat research reactor transient analysis

    International Nuclear Information System (INIS)

    Le Vinh Vinh; Nguyen Thai Sinh; Huynh Ton Nghiem; Luong Ba Vien; Pham Van Lam; Nguyen Kien Cuong

    2003-01-01

    DRSIM (Dalat Reactor SIMulation) computer code has been developed for Dalat reactor transient analysis. It is basically a coupled neutronics-hydrodynamics-heat transfer code employing point kinetics, one dimensional hydrodynamics and one dimensional heat transfer. The work was financed by VAEC and DNRI in the framework of institutional R and D programme. Some transient problems related to reactivity and loss of coolant flow was carried out by DRSIM using temperature and void coefficients calculated by WIMS and HEXNOD2D codes. (author)

  13. Study of the initiation of subcooled boiling during power transients

    International Nuclear Information System (INIS)

    VanVleet, R.J.

    1985-01-01

    An experimental investigation of boiling initiation during power transients has been conducted for horizontal-cylinder heating elements in degassed distilled water. Platinum elements, 0.127 and 0.250 mm in diameter, were internally heated electrically at a controlled superficial heat flux (power applied divided by surface area) increasing linearly with time at rates of 0.035 and 0.35 MW/m 2 s and corresponding test durations of 20 and 2 seconds. Tests were carried out at saturation temperatures from 100 to 195 0 C with bulk fluid subcooling from 0 to 30 K. During the course of a power transient, element temperature and superficial heat flux were measured electrically and the boiling initiation time was determined optically. It was found that the conditions for boiling initiation depended strongly on the pressure-temperature history of the heating element and surround fluid prior to the transient. Boiling initiation times were found to agree qualitatively with predictions of a model based on the contact-angle hysteresis concept. Brief prepressurization prior to a transient was found to increase dramatically the temperature and heat flux required for boiling initiation because of deactivation of boiling initiation sites. However, sites were re-activated during the transient and, in subsequent tests without prepressurization, no elevation in boiling initiation conditions was observed and results were in quantitative agreement with predictions of the model

  14. Steady state and transient critical heat flux examinations

    International Nuclear Information System (INIS)

    Szabados, L.

    1978-02-01

    In steady state conditions within the P.W.R. parameter range the critical heat flux correlations based on local parameters reproduce the experimental data with less deviations than those based on system parameters. The transient experiments were restricted for the case of power transients. A data processing method for critical heat flux measurements has been developed and the applicability of quasi steady state calculation has been verified. (D.P.)

  15. Transient regional osteoporosis.

    Science.gov (United States)

    Cano-Marquina, Antonio; Tarín, Juan J; García-Pérez, Miguel-Ángel; Cano, Antonio

    2014-04-01

    Transient regional osteoporosis (TRO) is a disease that predisposes to fragility fracture in weight bearing joints of mid-life women and men. Pregnant women may also suffer the process, usually at the hip. The prevalence of TRO is lower than the systemic form, associated with postmenopause and advanced age, but may be falsely diminished by under-diagnosis. The disease may be uni- or bilateral, and may migrate to distinct joints. One main feature of TRO is spontaneous recovery. Pain and progressive limitation in the functionality of the affected joint(s) are key symptoms. In the case of the form associated with pregnancy, difficulties in diagnosis derive from the relatively young age at presentation and from the clinical overlapping with the frequent aches during gestation. Densitometric osteoporosis in the affected region is not always present, but bone marrow edema, with or without joint effusion, is detected by magnetic resonance. There are not treatment guidelines, but the association of antiresorptives to symptomatic treatment seems to be beneficial. Surgery or other orthopedic interventions can be required for specific indications, like hip fracture, intra-medullary decompression, or other. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  16. Applied hydraulic transients

    CERN Document Server

    Chaudhry, M Hanif

    2014-01-01

    This book covers hydraulic transients in a comprehensive and systematic manner from introduction to advanced level and presents various methods of analysis for computer solution. The field of application of the book is very broad and diverse and covers areas such as hydroelectric projects, pumped storage schemes, water-supply systems, cooling-water systems, oil pipelines and industrial piping systems. Strong emphasis is given to practical applications, including several case studies, problems of applied nature, and design criteria. This will help design engineers and introduce students to real-life projects. This book also: ·         Presents modern methods of analysis suitable for computer analysis, such as the method of characteristics, explicit and implicit finite-difference methods and matrix methods ·         Includes case studies of actual projects ·         Provides extensive and complete treatment of governed hydraulic turbines ·         Presents design charts, desi...

  17. Defect detection using transient thermography

    International Nuclear Information System (INIS)

    Mohd Zaki Umar; Ibrahim Ahmad; Ab Razak Hamzah; Wan Saffiey Wan Abdullah

    2008-08-01

    An experimental research had been carried out to study the potential of transient thermography in detecting sub-surface defect of non-metal material. In this research, eight pieces of bakelite material were used as samples. Each samples had a sub-surface defect in the circular shape with different diameters and depths. Experiment was conducted using one-sided Pulsed Thermal technique. Heating of samples were done using 30 kWatt adjustable quartz lamp while infra red (IR) images of samples were recorded using THV 550 IR camera. These IR images were then analysed with ThermofitTMPro software to obtain the Maximum Absolute Differential Temperature Signal value, ΔΤ m ax and the time of its appearance, τ m ax (ΔΤ). Result showed that all defects were able to be detected even for the smallest and deepest defect (diameter = 5 mm and depth = 4 mm). However the highest value of Differential Temperature Signal (ΔΤ m ax), were obtained at defect with the largest diameter, 20 mm and at the shallowest depth, 1 mm. As a conclusion, the sensitivity of the pulsed thermography technique to detect sub-surface defects of bakelite material is proportionately related with the size of defect diameter if the defects are at the same depth. On the contrary, the sensitivity of the pulsed thermography technique inversely related with the depth of defect if the defects have similar diameter size. (Author)

  18. Output of the type 4051 and 4061 period meters during startup transients

    International Nuclear Information System (INIS)

    Cummins, J.D.

    1963-05-01

    The report describes a digital computer programme for the Ferranti Mercury computer. With this programme startup transients for the recently developed period meters Types 4051 and 4061 may be computed. The reactivity disturbances considered are steps and terminated ramps of reactivity. Due allowance is taken of the variable time constant which is a feature of these period meters. The reactor may be critical or subcritical initially as desired and the initial input time constant of the period meter may be zero or finite. Some representative transients obtained with the programme are presented and discussed. (author)

  19. Transient Stability Enhancement in Power System Using Static VAR Compensator (SVC

    Directory of Open Access Journals (Sweden)

    Youssef MOULOUDI

    2012-12-01

    Full Text Available In this paper, an indirect adaptive fuzzy excitation and static VAR (unit of reactive power, volt-ampere reactive compensator (SVC controller is proposed to enhance transient stability for the power system, which based on input-output linearization technique. A three-bus system, which contains a generator and static VAR compensator (SVC, is considered in this paper, the SVC is located at the midpoint of the transmission lines. Simulation results show that the proposed controller compared with a controller based on tradition linearization technique can enhance the transient stability of the power system under a large sudden fault, which may occur nearly at the generator bus terminal.

  20. Quantitative reactive modeling and verification.

    Science.gov (United States)

    Henzinger, Thomas A

    Formal verification aims to improve the quality of software by detecting errors before they do harm. At the basis of formal verification is the logical notion of correctness , which purports to capture whether or not a program behaves as desired. We suggest that the boolean partition of software into correct and incorrect programs falls short of the practical need to assess the behavior of software in a more nuanced fashion against multiple criteria. We therefore propose to introduce quantitative fitness measures for programs, specifically for measuring the function, performance, and robustness of reactive programs such as concurrent processes. This article describes the goals of the ERC Advanced Investigator Project QUAREM. The project aims to build and evaluate a theory of quantitative fitness measures for reactive models. Such a theory must strive to obtain quantitative generalizations of the paradigms that have been success stories in qualitative reactive modeling, such as compositionality, property-preserving abstraction and abstraction refinement, model checking, and synthesis. The theory will be evaluated not only in the context of software and hardware engineering, but also in the context of systems biology. In particular, we will use the quantitative reactive models and fitness measures developed in this project for testing hypotheses about the mechanisms behind data from biological experiments.

  1. Radial core expansion reactivity feedback in advanced LMRs: uncertainties and their effects on inherent safety

    International Nuclear Information System (INIS)

    Wigeland, R.A.; Moran, T.J.

    1988-01-01

    An analytical model for calculating radial core expansion, based on the thermal and elastic bowing of a single subassembly at the core periphery, is used to quantify the effect of uncertainties on this reactivity feedback mechanism. This model has been verified and validated with experimental and numerical results. The impact of these uncertainties on the safety margins in unprotected transients is investigated with SASSYS/SAS4A, which includes this model for calculating the reactivity feedback from radial core expansion. The magnitudes of these uncertainties are not sufficient to preclude the use of radial core expansion reactivity feedback in transient analysis

  2. Work plan: transient release from LMFBR fuel

    International Nuclear Information System (INIS)

    Kress, T.S.; Parker, G.W.; Fontana, M.H.

    1975-09-01

    The proposed LMFBR Transient Release Program at ORNL is designed to investigate, by means of ex-reactor experiments and analytical modeling, the release and transport of fuel, fission products, and transuranic elements from fast reactor cores in the event of certain hypothetical accidents. It is desired to experimentally produce energy depositions that are characteristic of severe hypothetical reactor transients by the application of direct electrical current to mixed-oxide fuels under sodium. The experimental program includes tests with and without sodium, investigations of alternative methods of generating fuel and sodium aerosols, the use of UO 2 as a fuel simulant, additions of tracers as fission product simulants, effects of radiation, and under-water and under-sodium efforts to study the behavior of the vapor bubble itself. Analytical modeling will accompany all phases of the program, and the data will be correlated with models developed. 21 references. (auth)

  3. A transient model to the thermal detonation

    International Nuclear Information System (INIS)

    Karachalios, K.

    1987-04-01

    The model calculates the escalation dynamics and the long time behavior of thermal detonation waves depending on the initial and boundary conditions (data of the premixture, ignition at a solid wall or at an open end, etc.). Especially, for a given mixture and a certain fragmentation behavior more than one stable steady-state cases resulted, depending on the applied ignition energy. Investigations showed a very good consistency between the transient model and a steady-state model which is based on the same physical description and includes an additional stability criterion. Also the influence of effects such as e.g. non-homogeneous coolant heating, spherical instead of plane wave propagation and inhomogeneities of the premixture on the development of the wave were investigated. Comparison calculations with large scale experiments showed that they can be well explained by means of the thermal detonation theory, especially considering the transient phase of the wave development. (orig./HP) [de

  4. Reactive Programming in Java

    CERN Document Server

    CERN. Geneva

    2017-01-01

    Reactive Programming in gaining a lot of excitement. Many libraries, tools, and frameworks are beginning to make use of reactive libraries. Besides, applications dealing with big data or high frequency data can benefit from this programming paradigm. Come to this presentation to learn about what reactive programming is, what kind of problems it solves, how it solves them. We will take an example oriented approach to learning the programming model and the abstraction.

  5. BN600 reactivity definition

    International Nuclear Information System (INIS)

    Zheltyshev, V.; Ivanov, A.

    2000-01-01

    Since 1980, the fast BN600 reactor with sodium coolant has been operated at Beloyarsk Nuclear Power Plant. The periodic monitoring of the reactivity modifications should be implemented in compliance with the standards and regulations applied in nuclear power engineering. The reactivity measurements are carried out in order to confirm the basic neutronic features of a BN600 reactor. The reactivity measurements are aimed to justify that nuclear safety is provided in course of the in-reactor installation of the experimental core components. Two reactivity meters are to be used on BN600 operation: 1. Digital on-line reactivity calculated under stationary reactor operation on power (approximation of the point-wise kinetics is applied). 2. Second reactivity meter used to define the reactor control rod operating components efficiency under reactor startup and take account of the changing efficiency of the sensor, however, this is more time-consumptive than the on-line reactivity meter. The application of two reactivity meters allows for the monitoring of the reactor reactivity under every operating mode. (authors)

  6. Development of Electrical Capacitance Sensors for Accident Tolerant Fuel (ATF) Testing at the Transient Reactor Test (TREAT) Facility

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Maolong; Ryals, Matthew; Ali, Amir; Blandford, Edward; Jensen, Colby; Condie, Keith; Svoboda, John; O' Brien, Robert

    2016-08-01

    A variety of instruments are being developed and qualified to support the Accident Tolerant Fuels (ATF) program and future transient irradiations at the Transient Reactor Test (TREAT) facility at Idaho National Laboratory (INL). The University of New Mexico (UNM) is working with INL to develop capacitance-based void sensors for determining the timing of critical boiling phenomena in static capsule fuel testing and the volume-averaged void fraction in flow-boiling in-pile water loop fuel testing. The static capsule sensor developed at INL is a plate-type configuration, while UNM is utilizing a ring-type capacitance sensor. Each sensor design has been theoretically and experimentally investigated at INL and UNM. Experiments are being performed at INL in an autoclave to investigate the performance of these sensors under representative Pressurized Water Reactor (PWR) conditions in a static capsule. Experiments have been performed at UNM using air-water two-phase flow to determine the sensitivity and time response of the capacitance sensor under a flow boiling configuration. Initial measurements from the capacitance sensor have demonstrated the validity of the concept to enable real-time measurement of void fraction. The next steps include designing the cabling interface with the flow loop at UNM for Reactivity Initiated Accident (RIA) ATF testing at TREAT and further characterization of the measurement response for each sensor under varying conditions by experiments and modeling.

  7. Explosive and radio-selected Transients: Transient Astronomy with ...

    Indian Academy of Sciences (India)

    40

    sitive measurements will lead to very accurate mass loss estimation in these supernovae. .... transients are powerful probes of intervening media owing to dispersion ...... A., & Chandra, P. 2011, Nature Communications,. 2, 175. Chakraborti, S.

  8. Transient-Switch-Signal Suppressor

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1995-01-01

    Circuit delays transmission of switch-opening or switch-closing signal until after preset suppression time. Used to prevent transmission of undesired momentary switch signal. Basic mode of operation simple. Beginning of switch signal initiates timing sequence. If switch signal persists after preset suppression time, circuit transmits switch signal to external circuitry. If switch signal no longer present after suppression time, switch signal deemed transient, and circuit does not pass signal on to external circuitry, as though no transient switch signal. Suppression time preset at value large enough to allow for damping of underlying pressure wave or other mechanical transient.

  9. Electromagnetic transients in power cables

    CERN Document Server

    da Silva, Filipe Faria

    2013-01-01

    From the more basic concepts to the most advanced ones where long and laborious simulation models are required, Electromagnetic Transients in Power Cables provides a thorough insight into the study of electromagnetic transients and underground power cables. Explanations and demonstrations of different electromagnetic transient phenomena are provided, from simple lumped-parameter circuits to complex cable-based high voltage networks, as well as instructions on how to model the cables.Supported throughout by illustrations, circuit diagrams and simulation results, each chapter contains exercises,

  10. Mechanisms of ignition by transient energy deposition: Regimes of combustion wave propagation

    OpenAIRE

    Kiverin, A. D.; Kassoy, D. R.; Ivanov, M. F.; Liberman, M. A.

    2013-01-01

    Regimes of chemical reaction wave propagating in reactive gaseous mixtures, whose chemistry is governed by chain-branching kinetics, are studied depending on the characteristics of a transient thermal energy deposition localized in a finite volume of reactive gas. Different regimes of the reaction wave propagation are initiated depending on the amount of deposited thermal energy, power of the source, and the size of the hot spot. The main parameters which define regimes of the combustion wave...

  11. Self-criticism, dependency, and stress reactivity: an experience sampling approach to testing Blatt and Zuroff's (1992) theory of personality predispositions to depression in high-risk youth.

    Science.gov (United States)

    Adams, Philippe; Abela, John R Z; Auerbach, Randy; Skitch, Steven

    2009-11-01

    S. J. Blatt and D. C. Zuroff's 1992 theory of personality predispositions to depression posits that individuals who possess high levels of self-criticism and/or dependency are vulnerable to developing depression following negative events. The current study used experience sampling methodology to test this theory in a sample of 49 children ages 7 to 14. Children completed measures of dependency, self-criticism, and depressive symptoms. Subsequently, children were given a handheld computer that signaled them to complete measures of depressive symptoms and negative events at randomly selected times over 2 months. Results of hierarchical linear modeling analyses indicated that higher levels of both self-criticism and dependency were associated with greater elevations in depressive symptoms following negative events. Furthermore, each personality predisposition remained a significant predictor of such elevations after controlling for the interaction between the other personality predisposition and negative events. The results suggest that dependency and self-criticism represent distinct vulnerability factors to depression in youth.

  12. Reactivity feedback models for SSC-K

    Energy Technology Data Exchange (ETDEWEB)

    Han, Do Hee; Kwon, Young Min; Kim, Kyung Du; Chang, Won Pyo [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-06-01

    Safety of KALIMER is assured by the inherent safety of the core and passive safety of the safety-related systems. For the safety analysis of a new reactor design such as KALIMER, analysis models, which are consistent with the design, have to be developed for a plant-wide transient and safety analysis code. Efforts for the development of reactivity feedback models for SSC-K, which is now being developed for the safety analysis of KALIMER, is described in this report. Models for Doppler, sodium density/void, fuel axial expansion, core radial expansion, and CRDL expansion have been developed. Test runs have been performed for the unprotected accident for the verification of the models. Use of KALIMER reactivity coefficients and future development of models for GEM and PSDRS would make it possible to analyze the response of KALIMER under TOP as well as LOF and LOHS accident conditions using SSC-K. (author). 5 refs., 64 figs., 2 tabs.

  13. A simple dynamic model and transient simulation of the nuclear power reactor on microcomputers

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yang Gee; Park, Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    A simple dynamic model is developed for the transient simulation of the nuclear power reactor. The dynamic model includes the normalized neutron kinetics model with reactivity feedback effects and the core thermal-hydraulics model. The main objective of this paper demonstrates the capability of the developed dynamic model to simulate various important variables of interest for a nuclear power reactor transient. Some representative results of transient simulations show the expected trends in all cases, even though no available data for comparison. In this work transient simulations are performed on a microcomputer using the DESIRE/N96T continuous system simulation language which is applicable to nuclear power reactor transient analysis. 3 refs., 9 figs. (Author)

  14. A simple dynamic model and transient simulation of the nuclear power reactor on microcomputers

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yang Gee; Park, Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A simple dynamic model is developed for the transient simulation of the nuclear power reactor. The dynamic model includes the normalized neutron kinetics model with reactivity feedback effects and the core thermal-hydraulics model. The main objective of this paper demonstrates the capability of the developed dynamic model to simulate various important variables of interest for a nuclear power reactor transient. Some representative results of transient simulations show the expected trends in all cases, even though no available data for comparison. In this work transient simulations are performed on a microcomputer using the DESIRE/N96T continuous system simulation language which is applicable to nuclear power reactor transient analysis. 3 refs., 9 figs. (Author)

  15. Use of plant operating history to define transient loads

    International Nuclear Information System (INIS)

    Dwivedy, K.K.

    1996-01-01

    Fatigue and crack growth analyses of components subjected to transient loads have been under continuous development during the recent past to include effects of environment on the components. The accuracy of the evaluation method on the predicted reliability of the components in the operating environment has become a focus of attention. Methods have integrated available material/component test data to improve evaluation techniques. However, in the area of definition of thermal transient loads the analyst still has to remain conservative, because no realistic guidelines have been developed to define thermal transients and their sequences. Fatigue re-evaluations of components are becoming increasingly necessary in operating plants as they age due to two reasons: (1) Components show age related degradation and cannot be repaired/replaced due to economic/logistic reasons. (2) Components experience transient conditions which were not considered in the original design. In either case, the evaluation of remaining life of components involves definition of transients and their sequence from the time the component was put in service until the end of life. As a common practice, initial plant design transients are used in a conservative definition of sequences to obtain results unrealistic for the situation, which sometimes leads to inaccurate estimate of the remaining life of components. The objective of this paper is to use plant operating history and plant monitoring data to provide procedures and techniques to define realistic transients for evaluation

  16. Awake reactivation predicts memory in humans

    OpenAIRE

    Staresina, Bernhard P.; Alink, Arjen; Kriegeskorte, Nikolaus; Henson, Richard N.

    2013-01-01

    How is new information converted into a memory trace? Here, we used functional neuroimaging to assess what happens to representations of new events after we first experience them. We found that a particular part of the medial temporal lobe, a brain region known to be critical for intact memory, spontaneously reactivates these events even when we are engaged in unrelated activities. Indeed, the extent to which such automatic reactivation occurs seems directly related to later memory performanc...

  17. Transients analysis able to lead Pressurised Water Reactors cores to degraded situations, analysis of resulting configurations

    International Nuclear Information System (INIS)

    Shin, Hyeong-Ki

    1999-01-01

    The severe accidents that occurred recently on nuclear reactors such as Chernobyl and T.M.1.2 have led many countries utilizing nuclear energy to examine their severe accident management. This thesis focuses on this problem and aims at analyzing, in terms of reactivity, degraded core behavior resulting from different accidental configurations. Two types of core degradation can be encountered: local degradation (the destruction of isolated assemblies in the core) or spreading degradation (the destruction of neighboring assemblies). The TMI accident is an example of spreading degradation in the core. The simplicity of implementing the control rod ejection accident calculation as compared to other accidental transients have motivated the choice of this accident as a determinant for local degraded core configurations. The control rod ejection accident presents important three dimensional effects and introduces neutronic/thermohydraulic coupling. The implementation and validation of already existing three dimensional coupled calculation scheme, allowed one to analyze the consequences of such an accident and to the conclusion that only unrealistic hypotheses of assembly permutation could lead to a partial core degradation. A reasonable estimate of stored energy in the assemblies with high bum up, in relation to the stored energy in the hot spot, was also obtained for the first time. The recently performed experiments (CABRI experiments) showed that in highly burned up assemblies, the capacity to store energy decreases strongly in relation to new assemblies. This first estimate of the distribution of produced energy between different assemblies, during the rod ejection accident, offers an important piece of knowledge in the study of the consequences of an eventual fuel cycle extension (presently under consideration by development companies). Finally, the analysis of degraded core reactivity itself has been performed for a vast range of the degraded core configurations

  18. Modeling of oxygen gas diffusion and consumption during the oxic transient in a disposal cell of radioactive waste

    International Nuclear Information System (INIS)

    De Windt, Laurent; Marsal, François; Corvisier, Jérôme; Pellegrini, Delphine

    2014-01-01

    Highlights: • This paper deals with the geochemistry of underground HLW disposals. • The oxic transient is a key issue in performance assessment (e.g. corrosion, redox). • A reactive transport model is explicitly coupled to gas diffusion and reactivity. • Application to in situ experiment (Tournemire laboratory) and HLW disposal cell. • Extent of the oxidizing/reducing front is investigated by sensitivity analysis. - Abstract: The oxic transient in geological radioactive waste disposals is a key issue for the performance of metallic components that may undergo high corrosion rates under such conditions. A previous study carried out in situ in the argillite formation of Tournemire (France) has suggested that oxic conditions could have lasted several years. In this study, a multiphase reactive transport model is performed with the code HYTEC to analyze the balance between the kinetics of pyrite oxidative dissolution, the kinetics of carbon steel corrosion and oxygen gas diffusion when carbon steel components are emplaced in the geological medium. Two cases were modeled: firstly, the observations made in situ have been reproduced, and the model established was then applied to a disposal cell for high-level waste (HLW) in an argillaceous formation, taking into account carbon steel components and excavated damaged zones (EDZ). In a closed system, modeling leads to a complete and fast consumption of oxygen in both cases. Modeling results are more consistent with the in situ test while considering residual voids between materials and/or a water unsaturated state allowing for oxygen gas diffusion (open conditions). Under similar open conditions and considering ventilation of the handling drifts, a redox contrast occurs between reducing conditions at the back of the disposal cell (with anoxic corrosion of steel and H 2 production) and oxidizing conditions at the front of the cell (with oxic corrosion of steel). The extent of the oxidizing/reducing front in the

  19. Electrospinning of reactive mesogens

    NARCIS (Netherlands)

    Yao, J.; Picot, O.T.; Hughes-Brittain, N.F.; Bastiaansen, C.W.M.; Peijs, T.

    2016-01-01

    The reinforcement potential of reactive liquid crystals or reactive mesogens (RMs) in electrospun fibers was investigated through the blending of two types of RMs (RM257 and RM82) with two types of thermoplastics; polyamide 6 (PA6) and poly(methyl methacrylate) (PMMA). Polymer/RM blends were

  20. Transient thyrotoxicosis during nivolumab treatment

    NARCIS (Netherlands)

    van Kooten, M. J.; van den Berg, G.; Glaudemans, A. W. J. M.; Hiltermann, T. J. N.; Groen, H. J. M.; Rutgers, A.; Links, T. P.

    Two patients presented with transient thyrotoxicosis within 2-4 weeks after starting treatment with nivolumab. This thyrotoxicosis turned into hypothyroidism within 6-8 weeks. Temporary treatment with a beta blocker may be sufficient.

  1. Transient Tsunamis in Lakes

    Science.gov (United States)

    Couston, L.; Mei, C.; Alam, M.

    2013-12-01

    A large number of lakes are surrounded by steep and unstable mountains with slopes prone to failure. As a result, landslides are likely to occur and impact water sitting in closed reservoirs. These rare geological phenomena pose serious threats to dam reservoirs and nearshore facilities because they can generate unexpectedly large tsunami waves. In fact, the tallest wave experienced by contemporary humans occurred because of a landslide in the narrow bay of Lituya in 1958, and five years later, a deadly landslide tsunami overtopped Lake Vajont's dam, flooding and damaging villages along the lakefront and in the Piave valley. If unstable slopes and potential slides are detected ahead of time, inundation maps can be drawn to help people know the risks, and mitigate the destructive power of the ensuing waves. These maps give the maximum wave runup height along the lake's vertical and sloping boundaries, and can be obtained by numerical simulations. Keeping track of the moving shorelines along beaches is challenging in classical Eulerian formulations because the horizontal extent of the fluid domain can change over time. As a result, assuming a solid slide and nonbreaking waves, here we develop a nonlinear shallow-water model equation in the Lagrangian framework to address the problem of transient landslide-tsunamis. In this manner, the shorelines' three-dimensional motion is part of the solution. The model equation is hyperbolic and can be solved numerically by finite differences. Here, a 4th order Runge-Kutta method and a compact finite-difference scheme are implemented to integrate in time and spatially discretize the forced shallow-water equation in Lagrangian coordinates. The formulation is applied to different lake and slide geometries to better understand the effects of the lake's finite lengths and slide's forcing mechanism on the generated wavefield. Specifically, for a slide moving down a plane beach, we show that edge-waves trapped by the shoreline and free

  2. Transient two-phase flow

    International Nuclear Information System (INIS)

    Hsu, Y.Y.

    1974-01-01

    The following papers related to two-phase flow are summarized: current assumptions made in two-phase flow modeling; two-phase unsteady blowdown from pipes, flow pattern in Laval nozzle and two-phase flow dynamics; dependence of radial heat and momentum diffusion; transient behavior of the liquid film around the expanding gas slug in a vertical tube; flooding phenomena in BWR fuel bundles; and transient effects in bubble two-phase flow. (U.S.)

  3. Nitrenes, carbenes, diradicals, and ylides. Interconversions of reactive intermediates.

    Science.gov (United States)

    Wentrup, Curt

    2011-06-21

    Rearrangements of aromatic and heteroaromatic nitrenes and carbenes can be initiated with either heat or light. The thermal reaction is typically induced by flash vacuum thermolysis, with isolation of the products at low temperatures. Photochemical experiments are conducted either under matrix isolation conditions or in solution at ambient temperature. These rearrangements are usually initiated by ring expansion of the nitrene or carbene to a seven-membered ring ketenimine, carbodiimide, or allene (that is, a cycloheptatetraene or an azacycloheptatetraene when a nitrogen is involved). Over the last few years, we have found that two types of ring opening take place as well. Type I is an ylidic ring opening that yields nitrile ylides or diazo compounds as transient intermediates. Type II ring opening produces either dienylnitrenes (for example, from 2-pyridylnitrenes) or 1,7-(1,5)-diradicals (such as those formed from 2-quinoxalinylnitrenes), depending on which of these species is better stabilized by resonance. In this Account, we describe our achievements in elucidating the nature of the ring-opened species and unraveling the connections between the various reactive intermediates. Both of these ring-opening reactions are found, at least in some cases, to dominate the subsequent chemistry. Examples include the formation of ring-opened ketenimines and carbodiimides, as well as the ring contraction reactions that form five-membered ring nitriles (such as 2- and 3-cyanopyrroles from pyridylnitrenes, N-cyanoimidazoles from 2-pyrazinyl and 4-pyrimidinylnitrenes, N-cyanopyrazoles from 2-pyrimidinylnitrenes and 3-pyridazinylnitrenes, and so forth). The mechanisms of formation of the open-chain and ring-contraction products were unknown at the onset of this study. In the course of our investigation, several reactions with three or more consecutive reactive intermediates have been unraveled, such as nitrene, seven-membered cyclic carbodiimide, and open-chain nitrile ylide

  4. Response of steam-water mixtures to pressure transients

    International Nuclear Information System (INIS)

    Hull, L.M.

    1985-01-01

    During the transition phase of a hypothetical core-disruptive accident in a liquid-metal fast breeder reactor, melting fuel-steel mixtures may begin to boil, resulting in a two-phase mixture of molten reactor fuel and steel vapor. Dispersal of this mixture by pressure transients may prevent recriticality of the fuel material. This paper describes the results of a series of experiments that investigated the response of two-phase mixtures to pressure transients. Simulant fluids (steam/water) were used in a transparent 10.2-cm-dia, 63.5-cm-long acrylic tube. The pressure transient was provided by releasing pressurized nitrogen from a supply tank. The data obtained are in the form of pressure-time records and high-speed movies. The varied parameters are initial void fraction (10% and 40%) and transient pressure magnitude (3.45 and 310 kPa)

  5. EP1000 anticipated transient without scram analyses

    International Nuclear Information System (INIS)

    Saiu, G.; Frogheri, M.; Schulz, T.L.

    2001-01-01

    The present paper summarizes the main results of the Anticipated Transient Without Scram (ATWS) analysis activity, performed for the European Passive Plant Program (EPP). The behavior of the EP1000 plant following an ATWS has been analyzed by means of the RELAP5/Mod3.2 code. An ATWS is defined as an Anticipated Transient accompanied by a common mode failure in the reactor protection system, such that the control rods do not scram as required to mitigate the consequences of the transient. According to the experience gained in PWR design, the limiting ATWS events, in a PWR, have been found to be the heatup transients caused by a reduction of heat removal capability by the secondary side of the plant. For this reason, the Loss of Normal Feedwater initiating event, to which the failure of the reactor scram is associated, has been analyzed. The purpose of the study is to verify the performance requirements set for the core feedback characteristics (that is to evaluate the effect of the low boron core neutron kinetic parameters), the overpressure protection system, and boration systems to cope with the EUR Acceptance Criteria for ATWS. Another purpose of this analysis was to support development of revised PSA success criteria that would reduce the contribution of ATWS to the large release frequency (LRF). The low boron core improved the basic EP1000 response to an ATWS event. In particular, the peak pressure was significantly lower than that which would result from a standard core configuration. The improved ATWS analysis results also permitted improved ATWS PSA success criteria. For example, the reduced peak pressure allows the use of other plant features to mitigate the event, including manual initiation of feed-bleed cooling in the event of PRHR HX failure. As a result, the core melt frequency and especially the LRF are significantly reduced. (author)

  6. Influence of transient flow on the mobility of strontium in unsaturated sand column

    International Nuclear Information System (INIS)

    Mazet, P.

    2008-10-01

    The reactive transport of 85 Sr was studied on laboratory columns, focusing on the influence of transient unsaturated flow (cycles of infiltration and redistribution) associated with controlled geochemistry (constant concentrations of major elements and stable strontium in water). An original experimental tool (gamma attenuation system) allows us to follow at the same time the variations of humidity of the soil and the migration of radionuclide, in a non-destroying and definite way. First stage of this study concerned the implementation of the experimental tool to measure transient hydraulic events within the columns of sand. Several experiments of transport of 85 Sr were then performed with different water condition (saturated, unsaturated, permanent and transient flow). Experimental results were simulated using the computer codes HYDRUS-1D (phenomenological approach with partition coefficient K d ) and HYTEC (mechanistic geochemical/transport approach). Confrontation between experience and modelling shows that, for our operating conditions, transfer of 85 Sr can be predicted with an 'operational' approach using: 1) simplified geochemical model with partition coefficient K d concerning interactive reaction with the soil (K d value determined independently on saturated column, with the same water geochemistry), 2) permanent saturated (or unsaturated) flow, taking into account the cumulated infiltrated water during unsaturated transient hydraulic events concerning hydrodynamic. Generalization of these results (area of validity) suggests that the 'cumulated infiltrated water + K d ' approach can be use, for controlled water geochemistry, when the numerical value of K d is fairly strong (K d ≥≥1), and that it is insensitive to the value of the water content. Moreover, the presence of immobile water (∼10%) recorded with tritium transport, is undetectable with strontium. Explanation of this result is allocated to the different characteristic time residence

  7. THEBES: a thermal hydraulic code for the calculation of transient two phase flow in bundle geometry

    International Nuclear Information System (INIS)

    Camous, F.

    1983-01-01

    The three dimensional thermal hydraulic code THEBES, capable to calculate transient boiling of sodium in rod bundles is described here. THEBES, derived from the transient single phase code SABRE-2A, was developed in CADARACHE by the SIES to analyse the SCARABEE N loss of flow experiments. This paper also presents the results of tests which were performed against various types of experiments: (1) transient boiling in a 7 pin bundle simulating a partial blockage at the bottom of a subassembly (rapid transient SCARABEE 7.2 experiment), (2) transient boiling in a 7 pin bundle simulating a coolant coast down (slow transient SCARABEE 7.3 experiment), (3) steady local and generalised boiling in a 19 pin bundle (GR 19 I experiment), (4) transient boiling in a 19 pin bundle simulating a coolant coast down (GR 19 I experiment), (5) steady local boiling in a 37 pin bundle with internal blockage (MOL 7C experiment). Excellent agreement was found between calculated and experimental results for these different situations. Our conclusion is that THEBES is able to calculate transient boiling of sodium in rod bundles in a quite satisfying way

  8. The qualitative criterion of transient angle stability

    DEFF Research Database (Denmark)

    Lyu, R.; Xue, Y.; Xue, F.

    2015-01-01

    In almost all the literatures, the qualitative assessment of transient angle stability extracts the angle information of generators based on the swing curve. As the angle (or angle difference) of concern and the threshold value rely strongly on the engineering experience, the validity and robust...... of these criterions are weak. Based on the stability mechanism from the extended equal area criterion (EEAC) theory and combining with abundant simulations of real system, this paper analyzes the criterions in most literatures and finds that the results could be too conservative or too optimistic. It is concluded...

  9. Transient gas flow through layered porous media

    International Nuclear Information System (INIS)

    Morrison, F.A. Jr.

    1975-01-01

    Low Reynolds number isothermal flow of an ideal gas through layered porous material was investigated analytically. Relations governing the transient flow in one dimension are obtained. An implicit, iterative, unconditionally stable finite difference scheme is developed for calculation of such flows. A computer code, SIROCCO, employing this technique has been written and implemented on the LLL computer system. A listing of the code is included. This code may be effectively applied to the evaluation of stemming plans for underground nuclear experiments. (U.S.)

  10. Performance of neutron kinetics models for ADS transient analyses

    International Nuclear Information System (INIS)

    Rineiski, A.; Maschek, W.; Rimpault, G.

    2002-01-01

    can also apply this approach for estimating errors of point-kinetics simulations or for ameliorating the employed point-kinetics models. Though the performance of the point-kinetics model can be insufficient in the subcritical case, the quasi-static approach is still valid if the shape steps are chosen properly. It is worthwhile to mention that in combination with properly computed correction factor tables, one can use the reactivity and power distributions obtained for 'critical' reactor models; this approach can simplify ADS-related application of conventional accident analyses codes (developed in the past for transient analyses of critical reactors). However, for analyzing severe transients in ADSs, which involve gross core material configuration changes, one can hardly avoid using of space-time kinetics methods, this holds similarly for critical reactor systems. (authors)

  11. Transient magnetoviscosity of dilute ferrofluids

    International Nuclear Information System (INIS)

    Soto-Aquino, Denisse; Rinaldi, Carlos

    2011-01-01

    The magnetic field induced change in the viscosity of a ferrofluid, commonly known as the magnetoviscous effect and parameterized through the magnetoviscosity, is one of the most interesting and practically relevant aspects of ferrofluid phenomena. Although the steady state behavior of ferrofluids under conditions of applied constant magnetic fields has received considerable attention, comparatively little attention has been given to the transient response of the magnetoviscosity to changes in the applied magnetic field or rate of shear deformation. Such transient response can provide further insight into the dynamics of ferrofluids and find practical application in the design of devices that take advantage of the magnetoviscous effect and inevitably must deal with changes in the applied magnetic field and deformation. In this contribution Brownian dynamics simulations and a simple model based on the ferrohydrodynamics equations are applied to explore the dependence of the transient magnetoviscosity for two cases: (I) a ferrofluid in a constant shear flow wherein the magnetic field is suddenly turned on, and (II) a ferrofluid in a constant magnetic field wherein the shear flow is suddenly started. Both simulations and analysis show that the transient approach to a steady state magnetoviscosity can be either monotonic or oscillatory depending on the relative magnitudes of the applied magnetic field and shear rate. - Research Highlights: →Rotational Brownian dynamics simulations were used to study the transient behavior of the magnetoviscosity of ferrofluids. →Damped and oscillatory approach to steady state magnetoviscosity was observed for step changes in shear rate and magnetic field. →A model based on the ferrohydrodynamics equations qualitatively captured the damped and oscillatory features of the transient response →The transient behavior is due to the interplay of hydrodynamic, magnetic, and Brownian torques on the suspended particles.

  12. Volume 3. Base technology FSAR support document: prefailure transient behavior and failure threshold. Status report, January 1975

    International Nuclear Information System (INIS)

    Baars, R.E.; Culley, G.E.; Davis, R.T.; Henderson, R.G.; Scott, J.H.

    1975-11-01

    The FFTF fuel pin design and fabrication data, irradiation histories, and postirradiation examination results are summarized for the HEDL/TREAT transient test experimental programs. For each experiment, the data include: (a) fuel pin fabrication parameters, (b) steady-state irradiation history, (c) transient test design conditions, (d) transient test data, and (e) postirradiation examination results

  13. Advanced methods for BWR transient and stability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, A; Wehle, F; Opel, S; Velten, R [AREVA, AREVA NP, Erlangen (Germany)

    2008-07-01

    The design of advanced Boiling Water Reactor (BWR) fuel assemblies and cores is governed by the basic requirement of safe, reliable and flexible reactor operation with optimal fuel utilization. AREVA NP's comprehensive steady state and transient BWR methodology allows the designer to respond quickly and effectively to customer needs. AREVA NP uses S-RELAP5/RAMONA as the appropriate methodology for the representation of the entire plant. The 3D neutron kinetics and thermal-hydraulics code has been developed for the prediction of system, fuel and core behavior and provides additional margins for normal operation and transients. Of major importance is the extensive validation of the methodology. The validation is based on measurements at AREVA NP's test facilities, and comparison of the predictions with a great wealth of measured data gathered from BWR plants during many years of operation. Three of the main fields of interest are stability analysis, operational transients and reactivity initiated accidents (RIAs). The introduced 3D methodology for operational transients shows significant margin regarding the operational limit of critical power ratio, which has been approved by the German licensing authority. Regarding BWR stability a large number of measurements at different plants under various conditions have been performed and successfully post-calculated with RAMONA. This is the basis of reliable pre-calculations of the locations of regional and core-wide stability boundaries. (authors)

  14. Advanced methods for BWR transient and stability analysis

    International Nuclear Information System (INIS)

    Schmidt, A.; Wehle, F.; Opel, S.; Velten, R.

    2008-01-01

    The design of advanced Boiling Water Reactor (BWR) fuel assemblies and cores is governed by the basic requirement of safe, reliable and flexible reactor operation with optimal fuel utilization. AREVA NP's comprehensive steady state and transient BWR methodology allows the designer to respond quickly and effectively to customer needs. AREVA NP uses S-RELAP5/RAMONA as the appropriate methodology for the representation of the entire plant. The 3D neutron kinetics and thermal-hydraulics code has been developed for the prediction of system, fuel and core behavior and provides additional margins for normal operation and transients. Of major importance is the extensive validation of the methodology. The validation is based on measurements at AREVA NP's test facilities, and comparison of the predictions with a great wealth of measured data gathered from BWR plants during many years of operation. Three of the main fields of interest are stability analysis, operational transients and reactivity initiated accidents (RIAs). The introduced 3D methodology for operational transients shows significant margin regarding the operational limit of critical power ratio, which has been approved by the German licensing authority. Regarding BWR stability a large number of measurements at different plants under various conditions have been performed and successfully post-calculated with RAMONA. This is the basis of reliable pre-calculations of the locations of regional and core-wide stability boundaries. (authors)

  15. Transient plasma cobalamin elevation in patients with pneumonia - two case reports

    DEFF Research Database (Denmark)

    Rahbek, Martin Torp; Scheller, Rudolf; Nybo, Mads

    2018-01-01

    We report two cases of transient significantly elevated plasma cobalamin (B12) in geriatric patients acutely admitted with fever, increased C-reactive protein and X-ray verified pneumonia. Extensive diagnostic workup did not reveal kidney or liver disease, neither any signs of cancer. Furthermore...

  16. Comparison of SAS3A and MELT-III predictions for a transient overpower hypothetical accident

    International Nuclear Information System (INIS)

    Wilburn, N.P.

    1976-01-01

    A comparison is made of the predictions of the two major codes SAS3A and MELT-III for the hypothetical unprotected transient overpower accident in the FFTF. The predictions of temperatures, fuel restructuring, fuel melting, reactivity feedbacks, and core power are compared

  17. Pressure transients across HEPA filters

    International Nuclear Information System (INIS)

    Gregory, W.; Reynolds, G.; Ricketts, C.; Smith, P.R.

    1977-01-01

    Nuclear fuel cycle facilities require ventilation for health and safety reasons. High efficiency particulate air (HEPA) filters are located within ventilation systems to trap radioactive dust released in reprocessing and fabrication operations. Pressure transients within the air cleaning systems may be such that the effectiveness of the filtration system is questioned under certain accident conditions. These pressure transients can result from both natural and man-caused phenomena: atmospheric pressure drop caused by a tornado or explosions and nuclear excursions initiate pressure pulses that could create undesirable conditions across HEPA filters. Tornado depressurization is a relatively slow transient as compared to pressure pulses that result from combustible hydrogen-air mixtures. Experimental investigation of these pressure transients across air cleaning equipment has been undertaken by Los Alamos Scientific Laboratory and New Mexico State University. An experimental apparatus has been constructed to impose pressure pulses across HEPA filters. The experimental equipment is described as well as preliminary results using variable pressurization rates. Two modes of filtration of an aerosol injected upstream of the filter is examined. A laser instrumentation for measuring the aerosol release, during the transient, is described

  18. Recent development of transient electronics

    Directory of Open Access Journals (Sweden)

    Huanyu Cheng

    2016-01-01

    Full Text Available Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be used in the human body as a diagnostic tool, for instance, or they can be used as environmentally friendly alternatives to existing electronics which disintegrate when exposed to water. Thus, the most crucial aspect of transient electronics is their ability to disintegrate in a practical manner and a review of the literature on this topic is essential for understanding the current capabilities of transient electronics and areas of future research. In the past, only partial dissolution of transient electronics was possible, however, total dissolution has been achieved with a recent discovery that silicon nanomembrane undergoes hydrolysis. The use of single- and multi-layered structures has also been explored as a way to extend the lifetime of the electronics. Analytical models have been developed to study the dissolution of various functional materials as well as the devices constructed from this set of functional materials and these models prove to be useful in the design of the transient electronics.

  19. Wide Field Radio Transient Surveys

    Science.gov (United States)

    Bower, Geoffrey

    2011-04-01

    The time domain of the radio wavelength sky has been only sparsely explored. Nevertheless, serendipitous discovery and results from limited surveys indicate that there is much to be found on timescales from nanoseconds to years and at wavelengths from meters to millimeters. These observations have revealed unexpected phenomena such as rotating radio transients and coherent pulses from brown dwarfs. Additionally, archival studies have revealed an unknown class of radio transients without radio, optical, or high-energy hosts. The new generation of centimeter-wave radio telescopes such as the Allen Telescope Array (ATA) will exploit wide fields of view and flexible digital signal processing to systematically explore radio transient parameter space, as well as lay the scientific and technical foundation for the Square Kilometer Array. Known unknowns that will be the target of future transient surveys include orphan gamma-ray burst afterglows, radio supernovae, tidally-disrupted stars, flare stars, and magnetars. While probing the variable sky, these surveys will also provide unprecedented information on the static radio sky. I will present results from three large ATA surveys (the Fly's Eye survey, the ATA Twenty CM Survey (ATATS), and the Pi GHz Survey (PiGSS)) and several small ATA transient searches. Finally, I will discuss the landscape and opportunities for future instruments at centimeter wavelengths.

  20. A faster reactor transient analysis methodology for PCs

    International Nuclear Information System (INIS)

    Ott, K.O.

    1991-10-01

    The simplified ANL model for LMR transient analysis, in which point kinetics as well as lumped descriptions of the heat transfer equations in all components are applied, is converted from a differential into an integral formulation. All differential balance equations are implicitly solved in terms of convolution integrals. The prompt jump approximation is applied as the strong negative feedback effectively keeps the net reactivity well below prompt critical. After implicit finite differencing of the convolution integrals, the kinetics equation assumes the form of a quadratic equation, the ''quadratic dynamics equation.'' This model forms the basis for GW-BASIC program, LTC, for LMR Transient Calculation program, which can effectively be run on a PC. The GW-BASIC version of the LTC program is described in detail in Volume 2 of this report

  1. Excitation of neutron flux waves in reactor core transients

    International Nuclear Information System (INIS)

    Carew, J.F.; Neogy, P.

    1983-01-01

    An analysis of the excitation of neutron flux waves in reactor core transients has been performed. A perturbation theory solution has been developed for the time-dependent thermal diffusion equation in which the absorption cross section undergoes a rapid change, as in a PWR rod ejection accident (REA). In this analysis the unperturbed reactor flux states provide the basis for the spatial representation of the flux solution. Using a simplified space-time representation for the cross section change, the temporal integrations have been carried out and analytic expressions for the modal flux amplitudes determined. The first order modal excitation strength is determined by the spatial overlap between the initial and final flux states, and the cross section perturbation. The flux wave amplitudes are found to be largest for rapid transients involving large reactivity perturbations

  2. Digital reactivity meter

    International Nuclear Information System (INIS)

    Jiang Zongbing

    1996-02-01

    The importance and the usual methods of reactivity measurement in a nuclear reactor are presented. Emphasis is put upon the calculation principle, software and hardware components, main specifications, application, as well as the features of the digital reactivity meter. The test results of operation in various reactors shown that the meter possess the following features: high accuracy, short response time, low output noise, high resolution, wide measuring range, simple and flexible to operate, high stability and reliability. In addition, the reactivity meter can save the measuring data automatically and have a perfect capability of self-verifying. It not only meet the requirement of the reactivity measurement in nuclear power plant, but also can be applied to various types of reactors. (1 tab.)

  3. Stress Reactivity in Insomnia.

    Science.gov (United States)

    Gehrman, Philip R; Hall, Martica; Barilla, Holly; Buysse, Daniel; Perlis, Michael; Gooneratne, Nalaka; Ross, Richard J

    2016-01-01

    This study examined whether individuals with primary insomnia (PI) are more reactive to stress than good sleepers (GS). PI and GS (n = 20 per group), matched on gender and age, completed three nights of polysomnography. On the stress night, participants received a mild electric shock and were told they could receive additional shocks during the night. Saliva samples were obtained for analysis of cortisol and alpha amylase along with self-report and visual analog scales (VAS). There was very little evidence of increased stress on the stress night, compared to the baseline night. There was also no evidence of greater stress reactivity in the PI group for any sleep or for salivary measures. In the GS group, stress reactivity measured by VAS scales was positively associated with an increase in sleep latency in the experimental night on exploratory analyses. Individuals with PI did not show greater stress reactivity compared to GS.

  4. Structure, Reactivity and Dynamics

    Indian Academy of Sciences (India)

    Understanding structure, reactivity and dynamics is the core issue in chemical ... functional theory (DFT) calculations, molecular dynamics (MD) simulations, light- ... between water and protein oxygen atoms, the superionic conductors which ...

  5. Taskable Reactive Agent Communities

    National Research Council Canada - National Science Library

    Myers, Karen

    2002-01-01

    The focus of Taskable Reactive Agent Communities (TRAC) project was to develop mixed-initiative technology to enable humans to supervise and manage teams of agents as they perform tasks in dynamic environments...

  6. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  7. Fuel pin response to an overpower transient in an LMFBR

    International Nuclear Information System (INIS)

    Grosberg, A.J.; Head, J.L.

    1979-01-01

    This paper describes a method by which the ability of a whole-core code accurately to predict the time and location of the first fuel pin failures may be tested. The method involves the use of a relatively simple whole-core code to 'drive' a sophisticated fuel pin code, which is far too complex to be used within a whole-core code but which is potentially capable of modelling reliably the response of an individual fuel pin. The method cannot follow accurately the subsequent course of the transient because the simple whole-core code does not model the reactivity effects of events which may follow pin failure. The codes used were the simple whole-core code FUTURE and the fuel pin behaviour code FRUMP. The paper describes an application of the method to analyse a hypothetical LMFBR accident in which the control rods were assumed to be driven from the core at maximum speed, with all trip circuits failed. Taking 0.5% clad strain as a clad failure criterion, failure was predicted to occur at the top of the active core at about 10s into the transient. A repeat analysis, using an alternative clad yield criterion which is thought to be more realistic, indicated failure at the same position but 24s into the transient. This is after the onset of sodium boiling. Pin failure at the top of the core are likely to cause negative reactivity changes. In this hypothetical accident, pin failures are likely, therefore, to have a moderating effect on the course of the transient. (orig.)

  8. Transient voltage oscillations in coils

    International Nuclear Information System (INIS)

    Chowdhuri, P.

    1985-01-01

    Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated

  9. Transient analysis of DTT rakes

    International Nuclear Information System (INIS)

    Kamath, P.S.; Lahey, R.T. Jr.

    1981-01-01

    This paper presents an analytical model for the determination of the cross-sectionally averaged transient mass flux of a two-phase fluid flowing in a conduit instrumented by a Drag-Disk Turbine Transducer (DTT) Rake and a multibeam gamma densitometer. Parametric studies indicate that for a typical blowdown transient, dynamic effects such as rotor inertia can be important for the turbine-meter. In contrast, for the drag-disk, a frequency response analysis showed that the quasisteady solution is valid below a forcing frequency of about 10 Hz, which is faster than the time scale normally encountered during blowdowns. The model showed reasonably good agreement with full scale transient rake data, where the flow regimes were mostly homogeneous or stratified, thus indicating that the model is suitable for the analysis of a DTT rake. (orig.)

  10. Estimating temperature reactivity coefficients by experimental procedures combined with isothermal temperature coefficient measurements and dynamic identification

    International Nuclear Information System (INIS)

    Tsuji, Masashi; Aoki, Yukinori; Shimazu, Yoichiro; Yamasaki, Masatoshi; Hanayama, Yasushi

    2006-01-01

    A method to evaluate the moderator coefficient (MTC) and the Doppler coefficient through experimental procedures performed during reactor physics tests of PWR power plants is proposed. This method combines isothermal temperature coefficient (ITC) measurement experiments and reactor power transient experiments at low power conditions for dynamic identification. In the dynamic identification, either one of temperature coefficients can be determined in such a way that frequency response characteristics of the reactivity change observed by a digital reactivity meter is reproduced from measured data of neutron count rate and the average coolant temperature. The other unknown coefficient can also be determined by subtracting the coefficient obtained from the dynamic identification from ITC. As the proposed method can directly estimate the Doppler coefficient, the applicability of the conventional core design codes to predict the Doppler coefficient can be verified for new types of fuels such as mixed oxide fuels. The digital simulation study was carried out to show the feasibility of the proposed method. The numerical analysis showed that the MTC and the Doppler coefficient can be estimated accurately and even if there are uncertainties in the parameters of the reactor kinetics model, the accuracies of the estimated values are not seriously impaired. (author)

  11. M. I. T. studies of transient X-ray phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Canizares, C R [Massachusetts Inst. of Tech., Cambridge (USA). Dept. of Physics

    1976-06-01

    A variety of transient X-ray phenomena have been studied by the M.I.T. X-ray Astronomy Group. Data from the OSO-7 satellite reveal both long and short time-scale transients. Extensive observations have been made of the Lupus X-ray Nova (3U1543-47) and of GX339-4 (MX1658-48) which may represent a very different type of transient source. A unique, intense X-ray flare lasting ten minutes was also recorded, and the X-ray emission from the active galaxy Cen A was found to vary significantly over a period of several days. In a recent balloon flight the Crab pulsar, NP0532, was observed to exhibit a transient pulsed component distinct from the usual main pulse and interpulse. A sounding-rocket experiment detected an ultrasoft transient X-ray source tentatively associated with SS Cygni, and preliminary results from SAS-3 show a very hard spectrum for the new source A0535+26. On the other hand, extensive OSO-7 null observations of both Type I and II supernovae and of the flaring radio star Algol make it unlikely that these types of objects are potent transient X-ray emitters.

  12. Transient analysis of multicavity klystrons

    International Nuclear Information System (INIS)

    Lavine, T.L.; Miller, R.H.; Morton, P.L.; Ruth, R.D.

    1988-09-01

    We describe a model for analytic analysis of transients in multicavity klystron output power and phase. Cavities are modeled as resonant circuits, while bunching of the beam is modeled using linear space-charge wave theory. Our analysis has been implemented in a computer program which we use in designing multicavity klystrons with stable output power and phase. We present as examples transient analysis of a relativistic klystron using a magnetic pulse compression modulator, and of a conventional klystron designed to use phase shifting techniques for RF pulse compression. 4 refs., 4 figs

  13. Transient formation of forbidden lines

    International Nuclear Information System (INIS)

    Rosmej, F.B.; Rosmej, O.N.

    1996-01-01

    An explanation of anomalously long time scales in the transient formation of forbidden lines is proposed. The concept is based on a collisionally induced density dependence of the relaxation times of metastable level populations in transient plasma. Generalization leads to an incorporation of diffusion phenomena. We demonstrate this new concept for the simplest atomic system: the He-like isoelectronic sequence. A new interpretation of the observed long duration and anomalously high intensity of spin-forbidden emission in hot plasmas is given. (author)

  14. Transient formation of forbidden lines

    Energy Technology Data Exchange (ETDEWEB)

    Rosmej, F.B. [Bochum Univ., Ruhr (Germany). Inst. fuer Experimentalphysik V; Rosmej, O.N. [VNIIFTRI, Moscow Region (Russian Federation). MISDC

    1996-05-14

    An explanation of anomalously long time scales in the transient formation of forbidden lines is proposed. The concept is based on a collisionally induced density dependence of the relaxation times of metastable level populations in transient plasma. Generalization leads to an incorporation of diffusion phenomena. We demonstrate this new concept for the simplest atomic system: the He-like isoelectronic sequence. A new interpretation of the observed long duration and anomalously high intensity of spin-forbidden emission in hot plasmas is given. (author).

  15. Volume 2. Base technology FSAR support document: prefailure transient behavior and failure threshold. Status report, January 1975

    International Nuclear Information System (INIS)

    Barrs, R.E.; Culley, G.E.; Davis, R.T.; Henderson, R.G.; Scott, J.H.

    1975-11-01

    The FFTF fuel pin design and fabrication data, irradiation history and postirradiation examination results are summarized for the General Electric and Argonne National Laboratory transient experiments in TREAT

  16. Modifying Memory: Selectively Enhancing and Updating Personal Memories for a Museum Tour by Reactivating Them

    Science.gov (United States)

    St. Jacques, Peggy L.; Schacter, Daniel L.

    2013-01-01

    Memory can be modified when reactivated, but little is known about how the properties and extent of reactivation can selectively affect subsequent memory. We developed a novel museum paradigm to directly investigate reactivation-induced plasticity for personal memories. Participants reactivated memories triggered by photos taken from a camera they wore during a museum tour and made relatedness judgments on novel photos taken from a different tour of the same museum. Subsequent recognition memory for events at the museum was better for memories that were highly reactivated (i.e., the retrieval cues during reactivation matched the encoding experience) than for memories that were reactivated at a lower level (i.e., the retrieval cues during reactivation mismatched the encoding experience), but reactivation also increased false recognition of photographs depicting stops that were not experienced during the museum tour. Reactivation thus enables memories to be selectively enhanced and distorted via updating, thereby supporting the dynamic and flexible nature of memory. PMID:23406611

  17. Reactive power compensator

    Science.gov (United States)

    El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  18. Reactive power compensator

    Energy Technology Data Exchange (ETDEWEB)

    El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Woodinville, WA); Chen, Mingliang (Kirkland, WA); Andexler, George (Everett, WA); Huang, Tony (Seattle, WA)

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  19. Transient attenuation in optical fibers

    International Nuclear Information System (INIS)

    Hopkins, A.A.; Kelly, R.E.; Looney, L.D.; Lyons, P.B.

    1984-01-01

    Low and high energy pulsed electron beams were used to generate radiation-induced transient attenuation in high-OH, Suprasil core, PCS fibers, demonstrating the energy dependence of the radiation damage and recovery mechanisms. A radiation resistant low-OH fiber was studied and its performance contrasted to that of high-OH materials. Several fibers with differing core compositions were also studied

  20. Charging transient in polyvinyl formal

    Indian Academy of Sciences (India)

    Unknown

    401–406. © Indian Academy of Sciences. 401. Charging transient in polyvinyl formal. P K KHARE*, P L JAIN† and R K PANDEY‡. Department of Postgraduate Studies & Research in Physics & Electronics, Rani Durgavati University,. Jabalpur 482 001, India. †Department of Physics, Government PG College, Damoh 470 ...

  1. Transient filament stretching rheometer II

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1997-01-01

    The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

  2. Fuel rod behaviour during transients

    International Nuclear Information System (INIS)

    Hughes, H.; Haste, T.J.; Cameron, R.F.; Sinclair, J.E.

    1982-04-01

    The fuel pin performance code SLEUTH, the transient codes FRAP-T5 and TRAFIC and the clad deformation code CANSWEL-2 are described. It is shown how the codes treat gas release, pin cooling, cladding deformation and interaction, gap conductance etc. The materials properties used are indicated. (author)

  3. Simulation Model of a Transient

    DEFF Research Database (Denmark)

    Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte

    2005-01-01

    This paper describes the simulation model of a controller that enables an active-stall wind turbine to ride through transient faults. The simulated wind turbine is connected to a simple model of a power system. Certain fault scenarios are specified and the turbine shall be able to sustain operati...

  4. Stationary and Transient Response Statistics

    DEFF Research Database (Denmark)

    Madsen, Peter Hauge; Krenk, Steen

    1982-01-01

    The covariance functions for the transient response of a linear MDOF-system due to stationary time limited excitation with an arbitrary frequency content are related directly to the covariance functions of the stationary response. For rational spectral density functions closed form expressions fo...

  5. Transient anisotropic magnetic field calculation

    International Nuclear Information System (INIS)

    Jesenik, Marko; Gorican, Viktor; Trlep, Mladen; Hamler, Anton; Stumberger, Bojan

    2006-01-01

    For anisotropic magnetic material, nonlinear magnetic characteristics of the material are described with magnetization curves for different magnetization directions. The paper presents transient finite element calculation of the magnetic field in the anisotropic magnetic material based on the measured magnetization curves for different magnetization directions. For the verification of the calculation method some results of the calculation are compared with the measurement

  6. Digital reactivity meter

    International Nuclear Information System (INIS)

    Copie, M.; Valantic, B.

    1978-01-01

    Digital reactivity meters (DRM) are mostly used as measuring instruments, e.g. for calibration of control rods, and there are only a few cases of their incorporation into the control systems of the reactors. To move in this direction there is more development work needed. First of all, fast algorithms are needed for inverse kinetics equations to relieve the computer for more important tasks of reactor model solving in real time. The next problem, currently under investigation, is the incorporation of the reactor thermal-hydraulic model into the DRM so that it can be used in the power range. Such an extension of DHM allows presentation not only of the instantaneous reactivity of the system, but also the inserted reactivity can be estimated from the temperature reactivity feed-backs. One of the applications of this concept is the anomalous digital reactivity monitor (ADRN) as part of the reactor protection system. As a solution of the first problem, a fast algorithm for solving the inverse kinetics equations has been implemented in the off-line program RODCAL on CDC 1700 computer and tested for its accuracy by performing different control rod calibrations on the reactor TRIGA

  7. OECD/DOE/CEA VVER-1000 Coolant Transient Benchmark. Summary Record of the Third Workshop (V1000-CT3)

    International Nuclear Information System (INIS)

    2005-01-01

    The overall objective of the VVER-1000 coolant transient (V1000CT) benchmark is to assess computer codes used in the safety analysis of VVER power plants, specifically for their use in analysis of reactivity transients in a VVER-1000. The V1000CT benchmark consists of two phases: V1000CT-1 is a simulation of the switching on of one main coolant pump (MCP) when the other three MCPs are in operation, and V1000CT-2 concerns calculation of coolant mixing tests and main steam line break (MSLB) scenarios. Each of the two phases contains three exercises. The reference problem chosen for simulation in Phase 1 is a MCP switching on when the other three main coolant pumps are in operation in a VVER-1000. This event is characterized by rapid increase in the flow through the core resulting in a coolant temperature decrease, which is spatially dependent. This leads to insertion of spatially distributed positive reactivity due to the modelled feedback mechanisms and non-symmetric power distribution. Simulation of the transient requires evaluation of core response from a multi-dimensional perspective (coupled three-dimensional neutronics/core thermal-hydraulics) supplemented by a one-dimensional simulation of the remainder of the reactor coolant system. Three exercises are defined in the framework of Phase 1: a) Exercise 1 - Point kinetics plant simulation; b) Exercise 2 - Coupled 3-D neutronics/core thermal-hydraulics response evaluation; c) Exercise 3 - Best-estimate coupled 3-D core/plant system transient modelling. In addition to the measured (experiment) scenario, extreme calculation scenarios were defined in the frame of Exercise 3 for better testing 3-D neutronics/thermal-hydraulics techniques. The proposals concerned: rod ejection simulations with scram set points at two different power levels. The technical topics presented at this workshop were: Review of the benchmark activities after the 2. Workshop; - Discussion of participant's feedback and introduced modifications

  8. Analysis of reactivity insertion accidents in PWR reactors

    International Nuclear Information System (INIS)

    Camargo, C.T.M.

    1978-06-01

    A calculation model to analyze reactivity insertion accidents in a PWR reactor was developed. To analyze the nuclear power transient, the AIREK-III code was used, which simulates the conventional point-kinetic equations with six groups of delayed neutron precursors. Some modifications were made to generalize and to adapt the program to solve the proposed problems. A transient thermal analysis model was developed which simulates the heat transfer process in a cross section of a UO 2 fuel rod with Zircalloy clad, a gap fullfilled with Helium gas and the correspondent coolant channel, using as input the nulcear power transient calculated by AIREK-III. The behavior of ANGRA-i reactor was analized during two types of accidents: - uncontrolled rod withdrawal from subcritical condition; - uncontrolled rod withdrawal at power. The results and conclusions obtained will be used in the license process of the Unit 1 of the Central Nuclear Almirante Alvaro Alberto. (Author) [pt

  9. Reactive model for developing applications using Vert.x toolkit

    OpenAIRE

    Ožbot, Žan

    2017-01-01

    Web and mobile applications consist of real-time events of different kinds in order to ensure the best possible user experience. To develop such applications, proper tools are needed and reactive programming is one of the possible solutions. Due to its many advantages, reactive programming is becoming an increasing reason to abandon standard object-oriented approach. Therefore, in this thesis we first describe the concepts of reactive programming and compare it to object-oriented programming....

  10. Modeling of the transient mobility in disordered organic semiconductors

    NARCIS (Netherlands)

    Germs, W.C.; Van der Holst, J.M.M.; Van Mensfoort, S.L.M.; Bobbert, P.A.; Coehoorn, R.

    2011-01-01

    In non-steady-state experiments, the electrical response of devicesbased on disordered organic semiconductors often shows a large transient contribution due to relaxation of the out-of-equilibrium charge-carrier distribution. We have developed a model describing this process, based only on the

  11. Transient Structured Distance as a Maneuver in Marital Therapy

    Science.gov (United States)

    Greene, Bernard L.; And Others

    1973-01-01

    Experience with 73 cases has shown the value of Transient Structured Distance as a maneuver in marriage therapy. While the TSD is a radical form of intervention with risks of anxiety reactions, homosexual panic, or divorce, it has proved effective with difficult forms of acute or chronic marital disharmony. (Author)

  12. Reactor transients tests for SNR fuel elements in HFR reactor

    International Nuclear Information System (INIS)

    Plitz, H.

    1989-01-01

    In HFR reactor, fuel pins of LMFBR reactors are putted in irradiation specimen capsules cooled with sodium for reactor transients tests. These irradiation capsules are instrumented and the experiences realized until this day give results on: - Fuel pins subjected at a continual variation of power - melting fuel - axial differential elongation of fuel pins

  13. ATWS: a reappraisal. Part 3. Frequency of anticipated transients

    International Nuclear Information System (INIS)

    McClymont, A.S.; Poehlman, B.W.

    1982-01-01

    This document is the first revision of Part 3 of the EPRI study of the anticipated transients without scram question. This revision includes an update of events at nuclear power plants which had led to fast reactor shutdowns (scrams). The purpose of this document is to present the nuclear power plant operating experience, reflecting the frequency of these events identified by their principal characteristics

  14. Forced convection mixing transients in the MITR core tank

    International Nuclear Information System (INIS)

    Hu, Lin-Wen; Meyer, J.E.; Bernard, J.A.

    1995-01-01

    This paper reports the results of forced convection mixing transient experiments that were studied in the core tank of the 5-MW Massachusetts Institute of Technology (MIT) nuclear reactor as part of the studies being conducted to support a facility upgrade to 10 MW

  15. 500 MHz transient digitizers based on GaAs CCDs

    International Nuclear Information System (INIS)

    Bryman, D.; Cresswell, J.V.; LeNoble, M.; Poutissou, R.

    1990-10-01

    A wide bandwidth transient digitizer based on a recently produced gallium arsenide charged coupled device is under development. The CCDs have 128 pixels and operate at 500 MHz. Initial testing of prototype modules in Experiment 787 at Brookhaven National Laboratory is reported. (Author) (8 refs., 10 figs.)

  16. 500 MHz transient digitizers based on GaAs CCDs

    International Nuclear Information System (INIS)

    Bryman, D.A.; Constable, M.; Cresswell, J.V.; Daviel, A.; LeNoble, M.; Mildenberger, J.; Poutissou, R.

    1996-11-01

    A system of 500 MHz transient digitizers based on gallium arsenide resistive gate charged coupled devices has been developed for an experiment studying rare K decays. CCDs with dynamic range of 8-bits and 128 or 320 pixels are used as analog pipelines. The CCD's are driven by a single phase transport system. Data readout and manipulation occurs at 15.6 MHz. (authors)

  17. Neighborhood disadvantage and adolescent stress reactivity

    Directory of Open Access Journals (Sweden)

    Daniel A. Hackman

    2012-10-01

    Full Text Available Lower socioeconomic status (SES is associated with higher levels of life stress, which in turn affect stress physiology. SES is related to basal cortisol and diurnal change, but it is not clear if SES is associated with cortisol reactivity to stress. To address this question, we examined the relationship between two indices of SES, parental education and concentrated neighborhood disadvantage, and the cortisol reactivity of African-American adolescents to a modified version of the Trier Social Stress Test. We found that concentrated disadvantage was associated with cortisol reactivity and this relationship was moderated by gender, such that higher concentrated disadvantage predicted higher cortisol reactivity and steeper recovery in boys but not in girls. Parental education, alone or as moderated by gender, did not predict reactivity or recovery, while neither education nor concentrated disadvantage predicted estimates of baseline cortisol. This finding is consistent with animal literature showing differential vulnerability, by gender, to the effects of adverse early experience on stress regulation and the differential effects of neighborhood disadvantage in adolescent males and females. This suggests that the mechanisms underlying SES differences in brain development and particularly reactivity to environmental stressors may vary across genders.

  18. [Transient amnesia in the elderly].

    Science.gov (United States)

    Sellal, François

    2006-03-01

    The two main aetiologies of transient amnesia in the elderly are idiopathic transient global amnesia (TGA) and iatrogenic or toxic amnesia. Vascular and epileptic amnesia are less common. According to the literature, transient psychogenic amnesia, which is a frequent cause of amnesia at age 30 to 50, is very rare in the elderly. TGA is the prototypical picture of transient amnesia. It occurs more often after age 50, with no identified cause, even if some authors accept emotional stress or minor head trauma as occasional precipitants. The mechanism of TGA remains a matter of discussion. It may be the consequence of a spreading depression similar to that described in migraine with aura, but other arguments support an ischemic mechanism. Iatrogenic amnesias are mainly caused by benzodiazepines (BZs) or anticholinergics. The former may occur in a non-anxious subject, who is not a usual consumer of BZ and takes a single dose. The latter are more often due to a hypersensitivity to anticholinergic drugs, in particular in patients presenting with a covert, incipient Alzheimer's disease. A vascular origin must be considered when amnesia is accompanied by other neurological symptoms, and when the regression of the amnesic disorder is slow, lasting several days. It results from lesions involving various mechanisms and locations, mainly subcortical. Partial seizures, most often mesio-temporal, more rarely frontal, may be the cause of transient amnesia in the elderly, in the absence of a past history of epilepsy. The red flag supportive of an epileptic origin is the repetition of stereotyped amnesic episodes. EEG demonstration of seizures may be difficult and the response to antiepileptic drugs effective on partial seizures is usually good.

  19. Impact of seasonal forcing on reactive ecological systems.

    Science.gov (United States)

    Vesipa, Riccardo; Ridolfi, Luca

    2017-04-21

    Our focus is on the short-term dynamics of reactive ecological systems which are stable in the long term. In these systems, perturbations can exhibit significant transient amplifications before asymptotically decaying. This peculiar behavior has attracted increasing attention. However, reactive systems have so far been investigated assuming that external environmental characteristics remain constant, although environmental conditions (e.g., temperature, moisture, water availability, etc.) can undergo substantial changes due to seasonal cycles. In order to fill this gap, we propose applying the adjoint non-modal analysis to study the impact of seasonal variations of environmental conditions on reactive systems. This tool allows the transient dynamics of a perturbation affecting non-autonomous ecological systems to be described. To show the potential of this approach, a seasonally forced prey-predator model with a Holling II type functional response is studied as an exemplifying case. We demonstrate that seasonalities can greatly affect the transient dynamics of the system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Research of the transient management in TQNPC

    International Nuclear Information System (INIS)

    Guo Longzhang; Lin Chuanqing

    2008-01-01

    Transient management is the basic technical subject in nuclear power plant. Since the Third Qinshan nuclear power company (TQNPC) successful completes the commissioning in 2003, the transient management work start at the transient management item selection and the flow definition. Now TQNPC have a complete transient management system and the management flow. In the last two years, TNQPC have finished the historic transient data collection for two units, and confirmed that the plant's key systems and equipments are at safe state. The development of the transient management subject would build a reliable foundation for the plant safe operation, plant lifetime management and periodic safety review. (author)

  1. Power and power-to-flow reactivity transfer functions in EBR-II [Experimental Breeder Reactor II] fuel

    International Nuclear Information System (INIS)

    Grimm, K.N.; Meneghetti, D.

    1989-01-01

    Reactivity transfer functions are important in determining the reactivity history during a power transient. Overall nodal transfer functions have been calculated for different subassembly types in the Experimental Breeder Reactor II (EBR-II). Steady-state calculations for temperature changes and, hence, reactivities for power changes have been separated into power and power-to-flow-dependent terms. Axial nodal transfer functions separated into power and power-to-flow-dependent components are reported in this paper for a typical EBR-II fuel pin. This provides an improved understanding of the time dependence of these components in transient situations

  2. Transient well flow in vertically heterogeneous aquifers

    Science.gov (United States)

    Hemker, C. J.

    1999-11-01

    A solution for the general problem of computing well flow in vertically heterogeneous aquifers is found by an integration of both analytical and numerical techniques. The radial component of flow is treated analytically; the drawdown is a continuous function of the distance to the well. The finite-difference technique is used for the vertical flow component only. The aquifer is discretized in the vertical dimension and the heterogeneous aquifer is considered to be a layered (stratified) formation with a finite number of homogeneous sublayers, where each sublayer may have different properties. The transient part of the differential equation is solved with Stehfest's algorithm, a numerical inversion technique of the Laplace transform. The well is of constant discharge and penetrates one or more of the sublayers. The effect of wellbore storage on early drawdown data is taken into account. In this way drawdowns are found for a finite number of sublayers as a continuous function of radial distance to the well and of time since the pumping started. The model is verified by comparing results with published analytical and numerical solutions for well flow in homogeneous and heterogeneous, confined and unconfined aquifers. Instantaneous and delayed drainage of water from above the water table are considered, combined with the effects of partially penetrating and finite-diameter wells. The model is applied to demonstrate that the transient effects of wellbore storage in unconfined aquifers are less pronounced than previous numerical experiments suggest. Other applications of the presented solution technique are given for partially penetrating wells in heterogeneous formations, including a demonstration of the effect of decreasing specific storage values with depth in an otherwise homogeneous aquifer. The presented solution can be a powerful tool for the analysis of drawdown from pumping tests, because hydraulic properties of layered heterogeneous aquifer systems with

  3. Reactive dispersive contaminant transport in coastal aquifers: Numerical simulation of a reactive Henry problem

    KAUST Repository

    Nick, H.M.

    2013-02-01

    The reactive mixing between seawater and terrestrial water in coastal aquifers influences the water quality of submarine groundwater discharge. While these waters come into contact at the seawater groundwater interface by density driven flow, their chemical components dilute and react through dispersion. A larger interface and wider mixing zone may provide favorable conditions for the natural attenuation of contaminant plumes. It has been claimed that the extent of this mixing is controlled by both, porous media properties and flow conditions. In this study, the interplay between dispersion and reactive processes in coastal aquifers is investigated by means of numerical experiments. Particularly, the impact of dispersion coefficients, the velocity field induced by density driven flow and chemical component reactivities on reactive transport in such aquifers is studied. To do this, a hybrid finite-element finite-volume method and a reactive simulator are coupled, and model accuracy and applicability are assessed. A simple redox reaction is considered to describe the degradation of a contaminant which requires mixing of the contaminated groundwater and the seawater containing the terminal electron acceptor. The resulting degradation is observed for different scenarios considering different magnitudes of dispersion and chemical reactivity. Three reactive transport regimes are found: reaction controlled, reaction-dispersion controlled and dispersion controlled. Computational results suggest that the chemical components\\' reactivity as well as dispersion coefficients play a significant role on controlling reactive mixing zones and extent of contaminant removal in coastal aquifers. Further, our results confirm that the dilution index is a better alternative to the second central spatial moment of a plume to describe the mixing of reactive solutes in coastal aquifers. © 2012 Elsevier B.V.

  4. Oxide fuel pin transient performance analysis and design with the TEMECH code

    International Nuclear Information System (INIS)

    Bard, F.E.; Dutt, S.P.; Hinman, C.A.; Hunter, C.W.; Pitner, A.L.

    1986-01-01

    The TEMECH code is a fast-running, thermal-mechanical-hydraulic, analytical program used to evaluate the transient performance of LMR oxide fuel pins. The code calculates pin deformation and failure probability due to fuel-cladding differential thermal expansion, expansion of fuel upon melting, and fission gas pressurization. The mechanistic fuel model in the code accounts for fuel cracking, crack closure, porosity decrease, and the temperature dependence of fuel creep through the course of the transient. Modeling emphasis has been placed on results obtained from Fuel Cladding Transient Test (FCTT) testing, Transient Fuel Deformation (TFD) tests and TREAT integral fuel pin experiments

  5. Ghrelin potentiates cardiac reactivity to stress by modulating sympathetic control and beta-adrenergic response.

    Science.gov (United States)

    Camargo-Silva, Gabriel; Turones, Larissa Córdova; da Cruz, Kellen Rosa; Gomes, Karina Pereira; Mendonça, Michelle Mendanha; Nunes, Allancer; de Jesus, Itamar Guedes; Colugnati, Diego Basile; Pansani, Aline Priscila; Pobbe, Roger Luis Henschel; Santos, Robson; Fontes, Marco Antônio Peliky; Guatimosim, Silvia; de Castro, Carlos Henrique; Ianzer, Danielle; Ferreira, Reginaldo Nassar; Xavier, Carlos Henrique

    2018-03-01

    Prior evidence indicates that ghrelin is involved in the integration of cardiovascular functions and behavioral responses. Ghrelin actions are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), which is expressed in peripheral tissues and central areas involved in the control of cardiovascular responses to stress. In the present study, we assessed the role of ghrelin - GHS-R1a axis in the cardiovascular reactivity to acute emotional stress in rats. Ghrelin potentiated the tachycardia evoked by restraint and air jet stresses, which was reverted by GHS-R1a blockade. Evaluation of the autonomic balance revealed that the sympathetic branch modulates the ghrelin-evoked positive chronotropy. In isolated hearts, the perfusion with ghrelin potentiated the contractile responses caused by stimulation of the beta-adrenergic receptor, without altering the amplitude of the responses evoked by acetylcholine. Experiments in isolated cardiomyocytes revealed that ghrelin amplified the increases in calcium transient changes evoked by isoproterenol. Taken together, our results indicate that the Ghrelin-GHS-R1a axis potentiates the magnitude of stress-evoked tachycardia by modulating the autonomic nervous system and peripheral mechanisms, strongly relying on the activation of cardiac calcium transient and beta-adrenergic receptors. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Modelling transient energy release from molten fuel coolant interaction debris

    International Nuclear Information System (INIS)

    Fletcher, D.F.

    1984-05-01

    A simple model of transient energy release in a Molten Fuel Coolant Interaction is presented. A distributed heat transfer model is used to examine the effect of heat transfer coefficient, time available for rapid energy heat transfer and particle size on transient energy release. The debris is assumed to have an Upper Limit Lognormal distribution. Model predictions are compared with results from the SUW series of experiments which used thermite-generated uranium dioxide molybdenum melts released below the surface of a pool of water. Uncertainties in the physical principles involved in the calculation of energy transfer rates are discussed. (author)

  7. Simulation of transient effects in the heavy ion fusion injectors

    International Nuclear Information System (INIS)

    Chen, Y.J.; Hewett, D.

    1993-01-01

    The authors have used the 2-D PIC code, GYMNOS, to study the transient behaviors in the Heavy Ion Fusion (HIF) injectors. GYMNOS simulations accurately provide the steady state Child-Langmuir current and the beam transient behavior within a planar diode. The simulations of the LBL HIF ESAC injector experiments agree well with the experimental data and EGUN steady state results. Simulations of the nominal HIF injectors have revealed the need to design the accelerating electrodes carefully to control the ion beam current, particularly the ion loss at the end of the bunch as the extraction voltage is reduced

  8. Simulation of transient effects in the heavy ion fusion injectors

    Science.gov (United States)

    Chen, Yu-Jiuan; Hewett, D. W.

    1993-05-01

    We have used the 2-D PIC code, GYMNOS, to study the transient behaviors in the Heavy Ion Fusion (HIF) injectors. GYMNOS simulations accurately provide the steady state Child-Langmuir current and the beam transient behavior within a planar diode. The simulations of the LBL HIF ESAC injector experiments agree well with the experimental data and EGUN steady state results. Simulations of the nominal HIF injectors have revealed the need to design the accelerating electrodes carefully to control the ion beam current, particularly the ion loss at the end of the bunch as the extraction voltage is reduced.

  9. BARS - a heterogeneous code for 3D pin-by-pin LWR steady-state and transient calculation

    International Nuclear Information System (INIS)

    Avvakumov, A.V.; Malofeev, V.M.

    2000-01-01

    A 3D pin-by-pin dynamic model for LWR detailed calculation was developed. The model is based on a coupling of the BARS neutronic code with the RELAP5/MOD3.2 thermal hydraulic code. This model is intended to calculate a fuel cycle, a xenon transient, and a wide range of reactivity initiated accidents in a WWER and a PWR. Galanin-Feinberg heterogeneous method was realized in the BARS code. Some results for a validation of the heterogeneous method are presented for reactivity coefficients, a pin-by-pin power distribution, and a fast pulse transient. (Authors)

  10. Assessment of the 3He pressure inside the CABRI transient rods - Development of a surrogate model based on measurements and complementary CFD calculations

    Science.gov (United States)

    Clamens, Olivier; Lecerf, Johann; Hudelot, Jean-Pascal; Duc, Bertrand; Cadiou, Thierry; Blaise, Patrick; Biard, Bruno

    2018-01-01

    CABRI is an experimental pulse reactor, funded by the French Nuclear Safety and Radioprotection Institute (IRSN) and operated by CEA at the Cadarache research center. It is designed to study fuel behavior under RIA conditions. In order to produce the power transients, reactivity is injected by depressurization of a neutron absorber (3He) situated in transient rods inside the reactor core. The shapes of power transients depend on the total amount of reactivity injected and on the injection speed. The injected reactivity can be calculated by conversion of the 3He gas density into units of reactivity. So, it is of upmost importance to properly master gas density evolution in transient rods during a power transient. The 3He depressurization was studied by CFD calculations and completed with measurements using pressure transducers. The CFD calculations show that the density evolution is slower than the pressure drop. Surrogate models were built based on CFD calculations and validated against preliminary tests in the CABRI transient system. Studies also show that it is harder to predict the depressurization during the power transients because of neutron/3He capture reactions that induce a gas heating. This phenomenon can be studied by a multiphysics approach based on reaction rate calculation thanks to Monte Carlo code and study the resulting heating effect with the validated CFD simulation.

  11. Assessment of the 3He pressure inside the CABRI transient rods - Development of a surrogate model based on measurements and complementary CFD calculations

    Directory of Open Access Journals (Sweden)

    Clamens Olivier

    2018-01-01

    Full Text Available CABRI is an experimental pulse reactor, funded by the French Nuclear Safety and Radioprotection Institute (IRSN and operated by CEA at the Cadarache research center. It is designed to study fuel behavior under RIA conditions. In order to produce the power transients, reactivity is injected by depressurization of a neutron absorber (3He situated in transient rods inside the reactor core. The shapes of power transients depend on the total amount of reactivity injected and on the injection speed. The injected reactivity can be calculated by conversion of the 3He gas density into units of reactivity. So, it is of upmost importance to properly master gas density evolution in transient rods during a power transient. The 3He depressurization was studied by CFD calculations and completed with measurements using pressure transducers. The CFD calculations show that the density evolution is slower than the pressure drop. Surrogate models were built based on CFD calculations and validated against preliminary tests in the CABRI transient system. Studies also show that it is harder to predict the depressurization during the power transients because of neutron/3He capture reactions that induce a gas heating. This phenomenon can be studied by a multiphysics approach based on reaction rate calculation thanks to Monte Carlo code and study the resulting heating effect with the validated CFD simulation.

  12. Transient compressible flows in porous media

    International Nuclear Information System (INIS)

    Morrison, F.A. Jr.

    1975-09-01

    Transient compressible flow in porous media was investigated analytically. The major portion of the investigation was directed toward improving and understanding of dispersion in these flows and developing rapid accurate numerical techniques for predicting the extent of dispersion. The results are of interest in the containment of underground nuclear experiments. The transient one-dimensional transport of a trace component in a gas flow is analyzed. A conservation equation accounting for the effects of convective transport, dispersive transport, and decay, is developed. This relation, as well as a relation governing the fluid flow, is used to predict trace component concentration as a function of position and time. A detailed analysis of transport associated with the isothermal flow of an ideal gas is done. Because the governing equations are nonlinear, numerical calculations are performed. The ideal gas flow is calculated using a highly stable implicit iterative procedure with an Eulerian mesh. In order to avoid problems of anomolous dispersion associated with finite difference calculation, trace component convection and dispersion are calculated using a Lagrangian mesh. Details of the Eulerian-Lagrangian numerical technique are presented. Computer codes have been developed and implemented on the Lawrence Livermore Laboratory computer system

  13. Reinstatement versus Reactivation Effects on Active Memory in Infants.

    Science.gov (United States)

    Adler, Scott A.; Rovee-Collier, Carolyn; Wilk, Amy

    2000-01-01

    Four experiments examined whether reinstatement and reactivation reminder paradigms affected memory performance of 102 three-month-olds. Results indicated that a single reinstatement protracted retention twice as long after training as a single reactivation. The novelty of the reminder stimulus also affected duration and specificity of memory in…

  14. Transfer of Old "Reactivated" Memory Retrieval Cues in Rats

    Science.gov (United States)

    Briggs, James F.; Riccio, David C.

    2008-01-01

    The present studies examined whether the retrieval of an old "reactivated" memory could be brought under the control of new contextual cues. In Experiment 1 rats trained in one context were exposed to different contextual cues either immediately, 60 or 120 min after a cued reactivation of the training memory. When tested in the shifted context,…

  15. Reactivation of Rate Remapping in CA3.

    Science.gov (United States)

    Schwindel, C Daniela; Navratilova, Zaneta; Ali, Karim; Tatsuno, Masami; McNaughton, Bruce L

    2016-09-07

    The hippocampus is thought to contribute to episodic memory by creating, storing, and reactivating patterns that are unique to each experience, including different experiences that happen at the same location. Hippocampus can combine spatial and contextual/episodic information using a dual coding scheme known as "global" and "rate" remapping. Global remapping selects which set of neurons can activate at a given location. Rate remapping readjusts the firing rates of this set depending on current experience, thus expressing experience-unique patterns at each location. But can the experience-unique component be retrieved spontaneously? Whereas reactivation of recent, spatially selective patterns in hippocampus is well established, it is never perfect, raising the issue of whether the experiential component might be absent. This question is key to the hypothesis that hippocampus can assist memory consolidation by reactivating and broadcasting experience-specific "index codes" to neocortex. In CA3, global remapping exhibits attractor-like dynamics, whereas rate remapping apparently does not, leading to the hypothesis that only the former can be retrieved associatively and casting doubt on the general consolidation hypothesis. Therefore, we studied whether the rate component is reactivated spontaneously during sleep. We conducted neural ensemble recordings from CA3 while rats ran on a circular track in different directions (in different sessions) and while they slept. It was shown previously that the two directions of running result in strong rate remapping. During sleep, the most recent rate distribution was reactivated preferentially. Therefore, CA3 can retrieve patterns spontaneously that are unique to both the location and the content of recent experience. The hippocampus is required for memory of events and their spatial contexts. The primary correlate of hippocampal activity is location in space, but multiple memories can occur in the same location. To be useful

  16. DETECTION OF FAST TRANSIENTS WITH RADIO INTERFEROMETRIC ARRAYS

    International Nuclear Information System (INIS)

    Bhat, N. D. R.; Chengalur, J. N.; Gupta, Y.; Prasad, J.; Roy, J.; Kudale, S. S.; Cox, P. J.; Bailes, M.; Burke-Spolaor, S.; Van Straten, W.

    2013-01-01

    Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg 2 of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.

  17. Detection of Fast Transients with Radio Interferometric Arrays

    Science.gov (United States)

    Bhat, N. D. R.; Chengalur, J. N.; Cox, P. J.; Gupta, Y.; Prasad, J.; Roy, J.; Bailes, M.; Burke-Spolaor, S.; Kudale, S. S.; van Straten, W.

    2013-05-01

    Next-generation radio arrays, including the Square Kilometre Array (SKA) and its pathfinders, will open up new avenues for exciting transient science at radio wavelengths. Their innovative designs, comprising a large number of small elements, pose several challenges in digital processing and optimal observing strategies. The Giant Metre-wave Radio Telescope (GMRT) presents an excellent test-bed for developing and validating suitable observing modes and strategies for transient experiments with future arrays. Here we describe the first phase of the ongoing development of a transient detection system for GMRT that is planned to eventually function in a commensal mode with other observing programs. It capitalizes on the GMRT's interferometric and sub-array capabilities, and the versatility of a new software backend. We outline considerations in the plan and design of transient exploration programs with interferometric arrays, and describe a pilot survey that was undertaken to aid in the development of algorithms and associated analysis software. This survey was conducted at 325 and 610 MHz, and covered 360 deg2 of the sky with short dwell times. It provides large volumes of real data that can be used to test the efficacies of various algorithms and observing strategies applicable for transient detection. We present examples that illustrate the methodologies of detecting short-duration transients, including the use of sub-arrays for higher resilience to spurious events of terrestrial origin, localization of candidate events via imaging, and the use of a phased array for improved signal detection and confirmation. In addition to demonstrating applications of interferometric arrays for fast transient exploration, our efforts mark important steps in the roadmap toward SKA-era science.

  18. Spring 5 & reactive streams

    CERN Multimedia

    CERN. Geneva; Clozel, Brian

    2017-01-01

    Spring is a framework widely used by the world-wide Java community, and it is also extensively used at CERN. The accelerator control system is constituted of 10 million lines of Java code, spread across more than 1000 projects (jars) developed by 160 software engineers. Around half of this (all server-side Java code) is based on the Spring framework. Warning: the speakers will assume that people attending the seminar are familiar with Java and Spring’s basic concepts. Spring 5.0 and Spring Boot 2.0 updates (45 min) This talk will cover the big ticket items in the 5.0 release of Spring (including Kotlin support, @Nullable and JDK9) and provide an update on Spring Boot 2.0, which is scheduled for the end of the year. Reactive Spring (1h) Spring Framework 5.0 has been released - and it now supports reactive applications in the Spring ecosystem. During this presentation, we'll talk about the reactive foundations of Spring Framework with the Reactor project and the reactive streams specification. We'll al...

  19. Reactivity of nitriles

    International Nuclear Information System (INIS)

    Kukushkin, Yu.N.

    1987-01-01

    Reactivity of coordination nitriles in transition metal (Ru, Mo, W, Zr, Hf) complexes, namely: transformation of nitriles of the first coordination sphere into N-acyl-substituted amides, amidines, nitrile interaction; with water, alkalines, alcoholes, hydrogen, azide and cyanide ions is considered. Introduction of acetonitrile molecule to uranium (4)-carbon double bond is discussed

  20. Clojure reactive programming

    CERN Document Server

    Borges, Leonardo

    2015-01-01

    If you are a Clojure developer who is interested in using Reactive Programming to build asynchronous and concurrent applications, this book is for you. Knowledge of Clojure and Leiningen is required. Basic understanding of ClojureScript will be helpful for the web chapters, although it is not strictly necessary.