Safe Operation of Nuclear Power Plants. Code of Practice and Technical Appendices

International Nuclear Information System (INIS)

1969-01-01

This book is in two parts. The first is a Code of Practice for the Safe Operation of Nuclear Power Plants and the second part is a compilation of technical appendices. Its object is to give information and illustrative examples that would be helpful in implementing the Code of Practice. This second part, although published under the same cover, is not part of the Code. Safe operation of a nuclear power plant postulates suitable siting and proper design, construction and management of the plant. Under the present Code of Practice for the Safe Operation of Nuclear Power Plants, those intending to operate the plant are recommended to prepare documentation which would deal with its operation and include safety analyses. The documentation in question would be reviewed by a regulatory body independent of the operating organization; operation would be authorized on the understanding that it would comply with limits and conditions designed to ensure safety. The Code may be subject to revision in the light of experience. The Appendices provide additional information together with some examples relating to certain topics dealt with in the Code; it must be emphasized that they are included as examples for information only and are not part of any recommendation. Purpose and scope: The recommendations in the Code are designed to protect the general public and the operating personnel from radiation hazards, and the Code forms part of the Agency's Safety Standards. The Code, which should be used in conjunction with the Agency's other Safety Standards, provides guidance and information to persons and authorities responsible for the operation of stationary nuclear power plants whose main function is the generation of thermal, mechanical or electrical power; it is not intended to apply to reactors used solely for experimental or research purposes. It sets forth minimum requirements which, it is believed, in the light of experience, must be met in order to achieve safe operation of a

Is nuclear power safe enough

Energy Technology Data Exchange (ETDEWEB)

Andresen, A F [Institutt for Atomenergi, Kjeller (Norway)

1979-01-01

The lecture formed a commentary on the report of the Norwegian Government's Commission on Nuclear power Safety which was published in October 1978. It was introductorily pointed out that 'safe' and 'safety' are not in themselves meaningful terms and that the probability of an occurrence is the real measure. The main items in the Commission's report have been core meltdown, releases during reprocessing, waste disposal, plutonium diversion and environmental impacts. The 21 members of the Commission were unanimous in 7 of the 8 chapters. In chapter 2, 'Summary and Conclusions', 3 members dissented from the majority opinion, that, subject to certain conditions, nuclear power was a safe and acceptable source of energy.

Inherent Safety Feature of Hybrid Low Power Research Reactor during Reactivity Induced Accident

Energy Technology Data Exchange (ETDEWEB)

Kim, DongHyun; Yum, Soo Been; Hong, Sung Teak; Lim, In-Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

Hybrid low power research reactor(H-LPRR) is the new design concept of low power research reactor for critical facility as well as education and training. In the case of typical low power research reactor, the purposes of utilization are the experiments for education of nuclear engineering students, Neutron Activation Analysis(NAA) and radio-isotope production for research purpose. H-LPRR is a light-water cooled and moderated research reactor that uses rod-type LEU UO{sub 2} fuels same as those for commercial power plants. The maximum core thermal power is 70kW and, the core is placed in the bottom of open pool. There are 1 control rod and 2 shutdown rods in the core. It is designed to cool the core by natural convection, retain negative feedback coefficient for entire fuel periods and operate for 20 years without refueling. Inherent safety in H-LPRR is achieved by passive design features such as negative temperature feedback coefficient and core cooling by natural convection during normal and emergency conditions. The purpose of this study is to find out that the inherent safety characteristics of H-LPRR is able to control the power and protect the reactor from the RIA(Reactivity induced accident). RIA analysis was performed to investigate the inherent safety feature of H-LPRR. As a result, it was found that the reactor controls its power without fuel damage in the event and that the reactor remains safe states inherently. Therefore, it is believed that high degree of safety inheres in H-LPRR.

A study on the Safe Operation of RHRS during Shut-Down and Low Power Operations of Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Jeon, Moon Hun; Sung, Chang Kyung; Kim, Yang Suk; You, Sun Oh; Joo, In Chul [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

1996-08-01

The main objective is to perform basic research for safe operation of RHRs, which is an important part in the safety analysis of nuclear reactors during a mid-loop operation of nuclear power plants. To achieve this objective, a series of experiments have been performed to simulate the wave phenomena of countercurrent flow that may occur in the hot legs during a mid-loop operation. The major contents and the scope are as follows, To collect and to analyse existing experimental works and also numerical works which have been carried out using large computer codes. To collect and to analyse existing works on the flow patterns of two-phase flows. To perform a series of experiments to simulate the wave phenomena for the countercurrent two-phase flow in hot legs. To obtain correlations for the interfacial friction factor and the flow patterns for a countercurrent flow from the experimentally measured parameters. To obtain the interfacial friction factor between the two-phases of air-water countercurrent flow in a horizontal pipe, a series of experiments have been performed using two different sections of 0.05 m in diameter, whose lengths are 2 m and 4 m, respectively. The results presented here can be used as the fundamental information to obtain the most important thermal-hydraulic parameters such as flow patterns and interfacial friction factors for air-water two-phase flows, which are necessary for safety analyses and operation of nuclear power plants during a mid-loop operation. 46 refs., 8 tabs., 35 figs., 3 ills. (author)

Experiments in a natural circulation loop with supercritical water at low powers

International Nuclear Information System (INIS)

Pilkhwal, D.S.; Sharma, Manish; Jana, S.S.; Vijayan, P.K.

2013-05-01

Earlier, 1/2 ″ uniform diameter Supercritical Pressure Natural Circulation Loop (SPNL) was set-up in hall-7, BARC for carrying out experiments related to supercritical fluids. The loop is a rectangular loop having two heaters and two coolers. Experiments were carried out with CO 2 under supercritical conditions for various pressures and different combinations of heater and cooler orientations. Since, the design conditions are more severe for supercritical water (SCW) experiments, the loop was modified for SCW by installing new test sections, pressurizer and power supply for operation with supercritical water. Experimental data were generated on steady state, heat transfer and stability under natural circulation conditions for the horizontal heater and horizontal cooler (HHHC) orientation with SCW up to a heater power of 8.5 kW. The flow rate data and instability data were compared with the predictions of in-house developed 1-D code NOLSTA, which showed reasonable agreement. The heat transfer coefficient data were also compared with the predictions of various correlations exhibit peak at bulk temperature lower than that obtained in the experiments. Most of these correlations predicted experimental data well in the pseudo-critical region. However, all correlations are matching well with experimental data beyond the pseudo-critical region. The details of the experimental facility, Experiments carried out and the results presented in this report. (author)

Criticality experiments with low enriched UO2 fuel rods in water containing dissolved gadolinium

International Nuclear Information System (INIS)

Bierman, S.R.; Murphy, E.S.; Clayton, E.D.; Keay, R.T.

1984-02-01

The results obtained in a criticality experiments program performed for British Nuclear Fuels, Ltd. (BNFL) under contract with the United States Department of Energy (USDOE) are presented in this report along with a complete description of the experiments. The experiments involved low enriched UO 2 and PuO 2 -UO 2 fuel rods in water containing dissolved gadolinium, and are in direct support of BNFL plans to use soluble compounds of the neutron poison gadolinium as a primary criticality safeguard in the reprocessing of low enriched nuclear fuels. The experiments were designed primarily to provide data for validating a calculation method being developed for BNFL design and safety assessments, and to obtain data for the use of gadolinium as a neutron poison in nuclear chemical plant operations - particularly fuel dissolution. The experiments program covers a wide range of neutron moderation (near optimum to very under-moderated) and a wide range of gadolinium concentration (zero to about 2.5 g Gd/l). The measurements provide critical and subcritical k/sub eff/ data (1 greater than or equal to k/sub eff/ greater than or equal to 0.87) on fuel-water assemblies of UO 2 rods at two enrichments (2.35 wt % and 4.31 wt % 235 U) and on mixed fuel-water assemblies of UO 2 and PuO 2 -UO 2 rods containing 4.31 wt % 235 U and 2 wt % PuO 2 in natural UO 2 respectively. Critical size of the lattices was determined with water containing no gadolinium and with water containing dissolved gadolinium nitrate. Pulsed neutron source measurements were performed to determine subcritical k/sub eff/ values as additional amounts of gadolinium were successively dissolved in the water of each critical assembly. Fission rate measurements in 235 U using solid state track recorders were made in each of the three unpoisoned critical assemblies, and in the near-optimum moderated and the close-packed poisoned assemblies of this fuel

Russian nuclear criticality experiments. Status and prospects

International Nuclear Information System (INIS)

Gagarinski, A.Yu.

2003-01-01

After the nuclear criticality had been reached on a uranium-graphite assembly for the first time in the Soviet Union on December 25, 1946, by I.V. Kurchatov and his team (1), the critical conditions in a great variety of multiplying media have been realized only in the Kurchatov Institute for at least several thousand times. Even the first Russian critical experiments carried out by Igor Kurchatov confirmed the unique merits of zero-power reactors: the most practically convenient range of parameters of kinetic response for variation of critical conditions, as well as invariability, over a wide range of the most important functions of neutron flux to reactor power. Neutron physics experiments have become a necessary stage in creation and improvement of nuclear reactors. Most critical experiments were performed mainly as a necessary stage of reactor design in the 60ies and 70ies, which has been the reactor 'golden age', when most of the total of over thousand nuclear reactors of various type and destination have been created worldwide. Though the ways of conducting critical measurements were very diversified, there are two main types of experiments. The first is so-called mock-up or prototype experiments when an exact (to the extent possible) simulation of the core is constructed to minimize the error in forecasting the operating reactor characteristics. Such experiments, which often represent the quality control of the core manufacturing and adjustment of core parameters to the design requirements, were carried out in Russia on critical assemblies of several plants, in design institutions (OKBM, Nizhni Novgorod; Electrostal and others), as well as in research centers (RRC 'Kurchatov Institute', etc.). Their results, which prevail today in the criticality database, even taking into account the capabilities provided by present-day calculation codes, are not well suited for new applications. It is hard to expect that the error resulting from inevitable idealization of

Development of low flow critical heat flux correlation for HANARO

International Nuclear Information System (INIS)

Park, Cheol; Chae, Hee Taek; Hang, Gee Yang.

1997-07-01

A low flow CHF correlation was developed for the safe operation of HANARO during the natural circulation cooling and the assessment of safety during the low flow condition of accident. The analytical model was applied to estimate the heat flux and the temperature distributions along the periphery of the fin at CHF conditions, and the predicted wall temperature at the sheath between the fins by the model agreed well with the measured one. The parametric trends of the CHF data for the finned geometry agreed with the general understanding from the previous studies for the unfinned annulus or tube geometries. It is revealed that the fin does not affect the CHF for low flow condition, although it increase the critical power due to larger heat transfer area. As the existing CHF correlation is proposed to predict the CHF for both finned and unfinned geometries at low flow and low pressure conditions. The developed correlation predicts the experimental CHF data with RMS errors of 13.7 %. (author). 19 refs., 3 tabs., 23 figs

Development of low flow critical heat flux correlation for HANARO

Energy Technology Data Exchange (ETDEWEB)

Park, Cheol; Chae, Hee Taek; Hang, Gee Yang

1997-07-01

A low flow CHF correlation was developed for the safe operation of HANARO during the natural circulation cooling and the assessment of safety during the low flow condition of accident. The analytical model was applied to estimate the heat flux and the temperature distributions along the periphery of the fin at CHF conditions, and the predicted wall temperature at the sheath between the fins by the model agreed well with the measured one. The parametric trends of the CHF data for the finned geometry agreed with the general understanding from the previous studies for the unfinned annulus or tube geometries. It is revealed that the fin does not affect the CHF for low flow condition, although it increase the critical power due to larger heat transfer area. As the existing CHF correlation is proposed to predict the CHF for both finned and unfinned geometries at low flow and low pressure conditions. The developed correlation predicts the experimental CHF data with RMS errors of 13.7 %. (author). 19 refs., 3 tabs., 23 figs.

Low power unattended defense reactor

International Nuclear Information System (INIS)

Kirchner, W.L.; Meier, K.L.

1984-01-01

A small, low power, passive, nuclear reactor electric power supply has been designed for unattended defense applications. Through innovative utilization of existing proven technologies and components, a highly reliable, ''walk-away safe'' design has been obtained. Operating at a thermal power level of 200 kWt, the reactor uses low enrichment uranium fuel in a graphite block core to generate heat that is transferred through heat pipes to a thermoelectric (TE) converter. Waste heat is removed from the TEs by circulation of ambient air. Because such a power supply offers the promise of minimal operation and maintenance (OandM) costs as well as no fuel logistics, it is particularly attractive for remote, unattended applications such as the North Warning System

Low power unattended defense reactor

International Nuclear Information System (INIS)

Kirchner, W.L.; Meier, K.L.

1984-01-01

A small, low power, passive, nuclear reactor electric power supply has been designed for unattended defense applications. Through innovative utilization of existing proven technologies and components, a highly reliable, walk-away safe design has been obtained. Operating at a thermal power level of 200 kWt, the reactor uses low enrichment uranium fuel in a graphite block core to generate heat that is transferred through heat pipes to a thermoelectric (TE) converter. Waste heat is removed from the TEs by circulation of ambient air. Because such a power supply offers the promise of minimal operation and maintenance (O and M) costs as well as no fuel logistics, it is particularly attractive for remote, unattended applications such as the North Warning System

Low density, microcellular, dopable, agar/gelatin foams for pulsed power experiments

Energy Technology Data Exchange (ETDEWEB)

McNamara, W.F. [Orion International Technologies, Inc., Albuquerque, NM (United States); Aubert, J.H. [Sandia National Lab., Albuquerque, NM (United States)

1997-04-01

Low-density, microcellular foams prepared from the natural polymers agar and gelatin have been developed for pulsed-power physics experiments. Numerous experiments were supported with foams having densities at or below 10 mg/cm{sup 3}. For some of the experiments, the agar/gelatin foam was uniformly doped with metallic elements using soluble salts. Depending on the method of preparation, cell sizes were typically below 10 microns and for one process were below 1.0 micron.

Determination of safe radioactive releases to the atmosphere from the nuclear power site, Dynefontein

International Nuclear Information System (INIS)

Basson, J.K.; Van As, D.

1976-01-01

South Africa's first nuclear power station, Koeberg A, is to be built by Escom at Dynefontein, 28 km north of Cape Town, and the experience gained at the National Nuclear Research Centre, Pelindaba, has been used by the AEB as basis for the pre-operational investigation. The capacity of the environment to accept airborne radioactive effluent safely depends on various local factors such as dispersion conditions, the ecology, the habits of the local population and the accumulation, through critical pathways, of pertinent radionuclides. Long-term average dilution factors at varying distances from a 100m stack have been calculated by ESCOM from mesometeorological data collected by the CSIR. On the basis of available data, permissible release rates are derived for radioisotopes of the noble gases (critical pathway:external cloud exposure), 131 I, 137 Cs, 106 Ru, 125 Sb and 114 Ce and tritium. Although final confirmation of these values can only be obtained after operation, such a pre-operational survey may serve as an example to conventional industry [af

Experimental Investigation on the Detection of Multiple Surface Cracks Using Vibrothermography with a Low-Power Piezoceramic Actuator.

Science.gov (United States)

Xu, Changhang; Xie, Jing; Zhang, Wuyang; Kong, Qingzhao; Chen, Guoming; Song, Gangbing

2017-11-23

Vibrothermography often employs a high-power actuator to generate heat on a specimen to reveal damage, however, the high-power actuator brings inconvenience to the application and possibly introduces additional damage to the inspected objects. This study uses a low-power piezoceramic transducer as the actuator of vibrothermography and explores its ability to detect multiple surface cracks in a metal part. Experiments were conducted on a thin aluminum beam with three cracks in different orientations. Detailed analyses of both thermograms and temperature data are presented to validate the proposed vibrothermography method. To further investigate the performance of the proposed vibrothermography method, we experimentally studied the effects of several critical factors, including the amplitude of excitation signal, specimen constraints, relative position between the transducer and cracks (the transducer is mounted on the same or the opposite side with the cracks). The results demonstrate that all cracks can be detected conveniently and simultaneously by using the proposed low-power vibrothermography. We also found that the magnitude of excitation signal and the specimen constraints have a great influence on detection results. Combined with effective data processing methods, such as Fourier transformation employed in this study, the proposed method provides a promising potential to detect multiple cracks on a metal surface in a safe and effective manner.

Implications of inherent safe nuclear power system

International Nuclear Information System (INIS)

Song, Yo-Taik

1987-01-01

The safety of present day nuclear power reactors and research reactors depends on a combination of design features of passive and active systems, and the alert judgement of their operators. A few inherently safe designs of nuclear reactors for power plants are currently under development. In these designs, the passive systems are emphasized, and the active systems are minimized. Also efforts are made to eliminate the potential for human failures that initiate the series of accidents. If a major system fails in these designs, the core is flooded automatically with coolants that flow by gravity, not by mechanical pumps or electromagnetic actuators. Depending on the choice of the coolants--water, liquid metal and helium gas--there are three principal types of inherently safe reactors. In this paper, these inherently safe reactor designs are reviewed and their implications are discussed. Further, future perspectives of their acceptance by nuclear industries are discussed. (author)

Construction of new critical experiment facilities in JAERI

International Nuclear Information System (INIS)

Takeshita, Isao; Itahashi, Takayuki; Ogawa, Kazuhiko; Tonoike, Kotaro; Matsumura, Tatsuro; Miyoshi, Yoshinori; Nakajima, Ken; Izawa, Naoki

1995-01-01

Japan Atomic Energy Research Institute (JAERI) has promoted the experiment research program on criticality safety since early in 1980s and two types of new critical facilities, Static Experiment Critical Facility (STACY) and Transient Experiment Critical Facility (TRACY) were completed on 1994 in Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) of JAERI Tokai Research Establishment. STACY was designed so as to obtain critical mass data of low enriched uranium and plutonium solution which is extensively handled in LWR fuel reprocessing plant. TRACY is the critical facility where critical accident phenomenon is demonstrated with low enriched uranium nitrate solution. For criticality safety experiments with both facilities, the Fuel Treatment System is attached to them, where composition and concentration of uranium and plutonium nitrate solutions are widely varied so as to obtain experiments data covering fuel solution conditions in reprocessing plant. Design performances of both critical facilities were confirmed through mock-up tests of important components and cold function tests. Hot function test has started since January of 1995 and some of the results on STACY are to be reported. (author)

Procedure for following external nuclear power plant operating experience

International Nuclear Information System (INIS)

Kostadinov, V.

2003-01-01

Slovenian Nuclear Safety Administration (SNSA) has developed computer database and the procedure for following-up and investigating external nuclear operating experience and administrative requirements. The SNSA's primary goal is to investigate safety significant events in due time, to analyze them from the regulatory point of view and to ensure that meaningful lessons be learned and used for improvement of the safe operation of Slovenian Nuclear Power Plant Krsko. Moreover, we intend to make uniform format and method for reporting broader spectrum of events analyzed including low level event reporting. (author)

Recommended nuclear criticality safety experiments in support of the safe transportation of fissile material

International Nuclear Information System (INIS)

Tollefson, D.A.; Elliott, E.P.; Dyer, H.R.; Thompson, S.A.

1993-01-01

Validation of computer codes and nuclear data (cross-section) libraries using benchmark quality critical (or certain subcritical) experiments is an essential part of a nuclear criticality safety evaluation. The validation results establish the credibility of the calculational tools for use in evaluating a particular application. Validation of the calculational tools is addressed in several American National Standards Institute/American Nuclear Society (ANSI/ANS) standards, with ANSI/ANS-8.1 being the most relevant. Documentation of the validation is a required part of all safety analyses involving significant quantities of fissile materials. In the case of transportation of fissile materials, the safety analysis report for packaging (SARP) must contain a thorough discussion of benchmark experiments, detailing how the experiments relate to the significant packaging and contents materials (fissile, moderating, neutron absorbing) within the package. The experiments recommended in this paper are needed to address certain areas related to transportation of unirradiated fissile materials in drum-type containers (packagings) for which current data are inadequate or are lacking

Low-power crystal and MEMS oscillators the experience of watch developments

CERN Document Server

Eric Vittoz

2010-01-01

Electronic oscillators using an electromechanical device as a frequency reference are irreplaceable components of systems-on-chip for time-keeping, carrier frequency generation and digital clock generation. With their excellent frequency stability and very large quality factor Q, quartz crystal resonators have been the dominant solution for more than 70 years. But new possibilities are now offered by micro-electro-mechanical (MEM) resonators, that have a qualitatively identical equivalent electrical circuit. Low-Power Crystal and MEMS Oscillators concentrates on the analysis and design of the most important schemes of integrated oscillator circuits. It explains how these circuits can be optimized by best exploiting the very high Q of the resonator to achieve the minimum power consumption compatible with the requirements on frequency stability and phase noise. The author has 40 years of experience in designing very low-power, high-performance quartz oscillators for watches and other battery operated systems an...

LEU-HTR critical experiment program for the PROTEUS facility in Switzerland

International Nuclear Information System (INIS)

Brogli, R.; Bucher, K.H.; Chawla, R.; Foskolos, K.; Luchsinger, H.; Mathews, D.; Sarlos, G.; Seiler, R.

1990-01-01

New critical experiments in the framework of an IAEA Coordinated Research Program on 'Validation of Safety Related Reactor Physics Calculations for Low Enriched HTRs' are planned at the PSI PROTEUS facility. The experiments are designed to supplement the experimental data base and reduce the design and licensing uncertainties for small- and medium-sized helium-cooled reactors using low-enriched uranium (LEU) and graphite high temperature fuel. The main objectives of the new experiments are to provide first-of-a-kind high quality experimental data on: 1) The criticality of simple, easy to interpret, single core region LEU HTR systems for several moderator-to-fuel ratios and several lattice geometries; 2) the changes in reactivity, neutron balance components and control rod effectiveness caused by water ingress into this type of reactor, and 3) the effects of the boron and/or hafnium absorbers that are used to modify the reactivity and the power distributions in typical HTR systems. Work on the design and licensing of the modified PROTEUS critical facility is now in progress with the HTR experiments scheduled to begin early in 1991. Several international partners will be involved in the planning, execution and analysis of these experiments in order to insure that they are relevant and cost effective with respect to the various gas cooled reactor national programs. (author)

LEU-HTR critical experiment program for the PROTEUS facility in Switzerland

Energy Technology Data Exchange (ETDEWEB)

Brogli, R; Bucher, K H; Chawla, R; Foskolos, K; Luchsinger, H; Mathews, D; Sarlos, G; Seiler, R [Paul Scherrer Institute, Laboratory for Reactor Physics and System Technology Wuerenlingen and Villigen, Villigen PSI (Switzerland)

1990-07-01

New critical experiments in the framework of an IAEA Coordinated Research Program on 'Validation of Safety Related Reactor Physics Calculations for Low Enriched HTRs' are planned at the PSI PROTEUS facility. The experiments are designed to supplement the experimental data base and reduce the design and licensing uncertainties for small- and medium-sized helium-cooled reactors using low-enriched uranium (LEU) and graphite high temperature fuel. The main objectives of the new experiments are to provide first-of-a-kind high quality experimental data on: 1) The criticality of simple, easy to interpret, single core region LEU HTR systems for several moderator-to-fuel ratios and several lattice geometries; 2) the changes in reactivity, neutron balance components and control rod effectiveness caused by water ingress into this type of reactor, and 3) the effects of the boron and/or hafnium absorbers that are used to modify the reactivity and the power distributions in typical HTR systems. Work on the design and licensing of the modified PROTEUS critical facility is now in progress with the HTR experiments scheduled to begin early in 1991. Several international partners will be involved in the planning, execution and analysis of these experiments in order to insure that they are relevant and cost effective with respect to the various gas cooled reactor national programs. (author)

RHIC BEAM ABORT KICKER POWER SUPPLY SYSTEM COMMISSIONING EXPERIENCE AND REMAINING ISSUES

International Nuclear Information System (INIS)

ZHANG, W.; AHRENS, L.A.; MI, J.; OERTER, B.; SANDERS, R.; SANDBERG, J.

2001-01-01

The RHIC Beam Abort Kicker Power Supply Systems commissioning experience and the remaining issues will be reported in this paper. The RHIC Blue Ring Beam Abort Kicker Power Supply System initial commissioning took place in June 1999. Its identical system in Yellow Ring was brought on line during Spring 2000. Each of the RHIC Beam Abort Kicker Power Supply Systems consists of five high voltage modulators and subsystems. These systems are critical devices for RHIC machine protection and environmental protection. They are required to be effective, reliable and operating with sufficient redundancy to safely abort the beam to its beam dump at the end of accumulation or at any time when they are commanded. To deflect 66 GeV ion beam to the beam absorbers, the RHIC Beam Abort Kicker Power Supply Systems were operated at 22 kV level. The RHIC 2000 commissioning run was very successful

Power source with spark-safe outlet

Energy Technology Data Exchange (ETDEWEB)

Tsesarenko, N P; Alekhin, A V

1982-01-01

The invention refers to the technique of electrical monitoring and control in systems operating in a spark-safe medium (for example, in coal mines). A more accurate area of application is mobile objects with autonomous source of electricity (mine diesel locomotives, battery electric locomotives etc.). The purpose of the invention is to simplify and to improve the reliability of the planned device, and also to expand the area of application for conditions when it is powered from an autonomous generator of direct voltage. This goal is achieved because the power source with spark-safe outlet (the source contains a thyristor of advance disconnection, connected by anode to the delimiting throttle, one outlet of which is connected to the capacitor included between the controlling electrode and the anode of the thyristor, and the capacitor is connected through the resistor parallel to the outlet clamps of the source, while the thyristor of emergency protection connected parallel to the inlet clamps of the power source) is additionally equipped with a current sensor, hercon, transistor key (included in series in the power circuit) and optron, whose emitter is connected parallel to the current sensor connected in series to the inlet of the power source, while the receiver of the optron is connected in a circuit for controlling the thyristor of emergency protection. Hercon is built into the core of the delimiting throttle and is connected to the circuit for controlling the transistor key.

Effects of low heterogeneity in fast critical assemblies

International Nuclear Information System (INIS)

Belov, S.P.; Dulin, V.A.; Zhukov, A.V.; Kuzin, E.N.; Mozhaev, V.K.; Sitnikov, V.I.; Tsibulya, A.M.; Shapar', A.V.; Zayfert, E.; Kuntsman, B.; Khayntsel'man, B.

1989-01-01

The problem of the low heterogeneity of fast critical assemblies, which are used to simulate fast reactors that are under design, has begun to assume increasing importance as the errors in nuclear data and group constants decrease and the capabilities of design codes improve. The design of the fuel channels of the fast critical assemblies of a BFS differs from that of the fuel subassemblies of a power reactor. The principal difference is that critical assemblies have a more heterogeneous structure than a reactor core does. As a result, the effects of this heterogeneity turn out to be appreciable for a number of functionals. Of particular interest was the measurement of the main neutronic characteristics of a fast reactor in its actual design and in the mockup produced by using BFS facilities. The authors measured and calculated the most important functionals (the ratios of the average cross sections of the main absorbing and fissioning elements, etc.) for both a homogeneous medium (fuel assemblies) and a heterogeneous medium (slugs, tubes) of practically identical composition. The objective of this work was to compare the discrepancy between experiment and calculations for the central functionals in the homogeneous and heterogeneous cases after corrections. This is a check of the accuracy of the simulation of homogeneous cores in fast power reactors by using the tools of the BFS fast critical assembly

Flight experience with lightweight, low-power miniaturized instrumentation systems

Science.gov (United States)

Hamory, Philip J.; Murray, James E.

1992-01-01

Engineers at the NASA Dryden Flight Research Facility (NASA-Dryden) have conducted two flight research programs with lightweight, low-power miniaturized instrumentation systems built around commercial data loggers. One program quantified the performance of a radio-controlled model airplane. The other program was a laminar boundary-layer transition experiment on a manned sailplane. The purpose of this paper is to report NASA-Dryden personnel's flight experience with the miniaturized instrumentation systems used on these two programs. The paper will describe the data loggers, the sensors, and the hardware and software developed to complete the systems. The paper also describes how the systems were used and covers the challenges encountered to make them work. Examples of raw data and derived results will be shown as well. Finally, future plans for these systems will be discussed.

Power control of SAFE reactor using fuzzy logic

International Nuclear Information System (INIS)

Irvine, Claude

2002-01-01

Controlling the 100 kW SAFE (Safe Affordable Fission Engine) reactor consists of design and implementation of a fuzzy logic process control system to regulate dynamic variables related to nuclear system power. The first phase of development concentrates primarily on system power startup and regulation, maintaining core temperature equilibrium, and power profile matching. This paper discusses the experimental work performed in those areas. Nuclear core power from the fuel elements is simulated using resistive heating elements while heat rejection is processed by a series of heat pipes. Both axial and radial nuclear power distributions are determined from neuronic modeling codes. The axial temperature profile of the simulated core is matched to the nuclear power profile by varying the resistance of the heating elements. The SAFE model establishes radial temperature profile equivalence by establishing 32 control zones as the nodal coordinates. Control features also allow for slow warm up, since complete shutoff can occur in the heat pipes if heat-source temperatures drop/rise below a certain minimum value, depending on the specific fluid and gas combination in the heat pipe. The entire system is expected to be self-adaptive, i.e., capable of responding to long-range changes in the space environment. Particular attention in the development of the fuzzy logic algorithm shall ensure that the system process remains at set point, virtually eliminating overshoot on start-up and during in-process disturbances. The controller design will withstand harsh environments and applications where it might come in contact with water, corrosive chemicals, radiation fields, etc

Low power constant fraction discriminator

International Nuclear Information System (INIS)

Krishnan, Shanti; Raut, S.M.; Mukhopadhyay, P.K.

2001-01-01

This paper describes the design of a low power ultrafast constant fraction discriminator, which significantly reduces the power consumption. A conventional fast discriminator consumes about 1250 MW of power whereas this low power version consumes about 440 MW. In a multi detector system, where the number of discriminators is very large, reduction of power is of utmost importance. This low power discriminator is being designed for GRACE (Gamma Ray Atmospheric Cerenkov Experiments) telescope where 1000 channels of discriminators are required. A novel method of decreasing power consumption has been described. (author)

A high resolution, low power time-of-flight system for the space experiment AMS

International Nuclear Information System (INIS)

Alvisi, D.; Anselmo, F.; Baldini, L.; Bari, G.; Basile, M.; Bellagamba, L.; Bruni, A.; Bruni, G.; Boscherini, D.; Casadei, D.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Polini, A.; Recupero, S.; Sartorelli, G.; Williams, C.; Zichichi, A.

1999-01-01

The system of plastic scintillator counters for the AMS experiment is described. The main characteristics of the detector are: (a) large sensitive area (four 1.6 m 2 planes) with small dead space; (b) low-power consumption (150 W for the power and the read-out electronics of 336 PMs); (c) 120 ps time resolution

How safe are nuclear power plants

International Nuclear Information System (INIS)

Danzmann, H.J.

1976-01-01

The question 'how safe are nuclear power plants' can be answered differently - it depends on how the term 'safety' is understood. If the 'safety of supply' is left out as a possibility of interpretation, then the alternative views remain: Operational safety in the sense of reliability and safety of personnel and population. (orig.) [de

Stopping power and range relations for low and high Z ions in solids: a critical analysis

International Nuclear Information System (INIS)

Virk, H.S.; Randhawa, G.S.

1997-01-01

A critical analysis of various stopping power and range formulations has been made by comparing the calculated stopping power and range values with corresponding experimental values for different low Z (1≤Z≤8) and high Z projectiles (54≤Z≤92) in different targets, e.g. Be, C, Al, Au, Pb, CR-39, Lexan, Mylar, LR-115, CH, (CH)n, TRIFOL-TN, etc. atvarious low and high energies. A comparative study has been made by taking into consideration different target and projectile combinations, e.g., heavy ion-light target, light ion-heavy target and light ion -light target etc., Overall the Ziegler formulation (TRIM-95) provides the best agreement with the experimental results for all projectile and target combinations except for heavy ion-light target combination where it underestimates the stopping power data and overestimates the range data in the range, 2-50 MeV/u. Mukherjee and Nayak formulation totally fails at relativistic and low energies of the projectile, irrespective of the projectile-target combination. Northcliffe and Schilling formulation does not show any particular trend. Benton and Henke formulation gives good agreement between experimental and theoretical data within the range of experimental errors. (orig.)

Estimation of residual stress distribution for pressurizer nozzle of Kori nuclear power plant considering safe end

Energy Technology Data Exchange (ETDEWEB)

Song, Tae Kwang; Bae, Hong Yeol; Chun, Yun Bae; Oh, Chang Young; Kim, Yun Jae [Korea University, Seoul (Korea, Republic of); Lee, Kyoung Soo; Park, Chi Yong [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

2008-08-15

In nuclear power plants, ferritic low alloy steel nozzle was connected with austenitic stainless steel piping system through alloy 82/182 butt weld. Accurate estimation of residual stress for weldment is important in the sense that alloy 82/182 is susceptible to stress corrosion cracking. There are many results which predict residual stress distribution for alloy 82/182 weld between nozzle and pipe. However, nozzle and piping system usually connected through safe end which has short length. In this paper, residual stress distribution for pressurizer nozzle of Kori nuclear power plant was predicted using FE analysis, which considered safe end. As a result, existing residual stress profile was redistributed and residual stress of inner surface was decreased specially. It means that safe end should be considered to reduce conservatism when estimating the piping system.

Reactor Dynamics Experiments with a Sub-Critical Assembly

International Nuclear Information System (INIS)

Miley, G.H.; Yang, Y.; Wu, L.; Momota, H.

2004-01-01

A resurgence in use of nuclear power is now underway worldwide. However due to the shutdown of many university research reactors , student laboratories must rely more heavily on use of sub-critical assemblies. Here a driven sub-critical is described that uses a cylindrical Inertial Electrostatic Confinement (IEC) device to provide a fusion neutron source. The small IEC neutron source would be inserted in a fuel element position, with its power input controlled externally at a control panel. This feature opens the way to use of the critical assembly for a number of transient experiments such as sub-critical pulsing and neutron wave propagation. That in turn adds important new insights and excitement for the student teaching laboratory

Benchmark critical experiments on low-enriched uranium oxide systems with H/U = 0.77

International Nuclear Information System (INIS)

Tuck, G.; Oh, I.

1979-08-01

Ten benchmark experiments were performed at the Critical Mass Laboratory at Rockwell International's Rocky Flats Plant, Golden, Colorado, for the US Nuclear Regulatory Commission. They provide accurate criticality data for low-enriched damp uranium oxide (U 3 O 8 ) systems. The core studied consisted of 152 mm cubical aluminum cans containing an average of 15,129 g of low-enriched (4.46% 235 U) uranium oxide compacted to a density of 4.68 g/cm 3 and with an H/U atomic ratio of 0.77. One hundred twenty five (125) of these cans were arranged in an approx. 770 mm cubical array. Since the oxide alone cannot be made critical in an array of this size, an enriched (approx. 93% 235 U) metal or solution driver was used to achieve criticality. Measurements are reported for systems having the least practical reflection and for systems reflected by approx. 254-mm-thick concrete or plastic. Under the three reflection conditions, the mass of the uranium metal driver ranged from 29.87 kg to 33.54 kg for an oxide core of 1864.6 kg. For an oxide core of 1824.9 kg, the weight of the high concentration (351.2 kg U/m 3 ) solution driver varied from 14.07 kg to 16.14 kg, and the weight of the low concentration (86.4 kg U/m 3 ) solution driver from 12.4 kg to 14.0 kg

Coretran/Vipre assembly critical power assessment against Nupec BWR experiments

International Nuclear Information System (INIS)

Aounallah, Y.

2001-01-01

This study has been performed, in the framework of the STARS project, to assess CORETRAN-01/VIPRE-02 code capability to predict critical heat flux conditions for BWR fuel assemblies. The assessment is based on comparisons of the code results with the NUPEC steady-state critical power measurements on full-scale assemblies tested under a range of flow conditions. Two assembly types were considered, the standard BWR 8 x 8 and the so-called ''high-burnup'' assembly, similar to GE-10. Code modelling options that have a significant impact on the results have been identified, along with code limitations. (author)

Critical heat flux experiments in tight lattice core

Energy Technology Data Exchange (ETDEWEB)

Kureta, Masatoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2002-12-01

Fuel rods of the Reduced-Moderation Water Reactor (RMWR) are so designed to be in tight lattices as to reduce moderation and achieve higher conversion ratio. As for the BWR type reactor coolant flow rate is reduced small compared with the existing BWR, so average void fraction comes to be langer. In order to evaluate thermo hydraulic characteristics of designed cores, critical heat flux experiments in tight lattice core have been conducted using simulated high pressure coolant loops for both the PWR and BWR seven fuel rod bundles. Experimental data on critical heat flux for full bundles have been accumulated and applied to assess the critical power of designed cores using existing codes. Evaluated results are conservative enough to satisfy the limiting condition. Further experiments on axial power distribution effects and 37 fuel rod bundle tests will be performed to validate thermohydraulic characteristics of designed cores. (T. Tanaka)

Critical heat flux experiments in tight lattice core

International Nuclear Information System (INIS)

Kureta, Masatoshi

2002-01-01

Fuel rods of the Reduced-Moderation Water Reactor (RMWR) are so designed to be in tight lattices as to reduce moderation and achieve higher conversion ratio. As for the BWR type reactor coolant flow rate is reduced small compared with the existing BWR, so average void fraction comes to be langer. In order to evaluate thermo hydraulic characteristics of designed cores, critical heat flux experiments in tight lattice core have been conducted using simulated high pressure coolant loops for both the PWR and BWR seven fuel rod bundles. Experimental data on critical heat flux for full bundles have been accumulated and applied to assess the critical power of designed cores using existing codes. Evaluated results are conservative enough to satisfy the limiting condition. Further experiments on axial power distribution effects and 37 fuel rod bundle tests will be performed to validate thermohydraulic characteristics of designed cores. (T. Tanaka)

Critical power for lower hybrid current drive

International Nuclear Information System (INIS)

Assis, A.S. de; Sakanaka, P.H.; Azevedo, C.A. de; Busnardo-Neto, J.

1995-11-01

We have solved numerically the quasilinear Fokker-Planck equation which models the critical power for lower hybrid wave current drive. An exact value for the critical power necessary for current saturation, for tokamak current drive experiments, has been obtained. The nonlinear treatment presented here leads to a final profile for the parallel distribution function which is a plateau only in a part of the resonance region. This form of the distribution function is intermediate between two well known results: a plateau throughout the resonance region for the linear strong-source regime, D wave >> D coll and no plateau at all in the resonance region the linear weak-source regimen, D wave coll . The strength of the external power source and the value of the dc electric field are treated as given parameters in the integration scheme. (author). 24 refs, 6 figs

Low voltage powering of on-detector electronics for HL-LHC experiments upgrades

CERN Document Server

Bobillier, Vincent; Vasey, Francois; Karmakar, Sabyasachi; Maity, Manas; Roy, Subhasish; Kundu, Tapas Kumar

2018-01-01

All LHC experiments will be upgraded during the next LHC long shutdowns (LS2 and LS3). The increase in resolution and luminosity and the use of more advanced CMOS technology nodes typically implies higher current consumption of the on-detector electronics. In this context, and in view of limiting the cable voltage drop, point-of-load DC-DC converters will be used on detector. This will have a direct impact on the existing powering scheme, implying new AC-DC and/or DC-DC stages as well as changes in the power cabling infrastructure. This paper presents the first results obtained while evaluating different LV powering schemes and distribution layouts for HL-LHC trackers. The precise low voltage power source requirements are being assessed and understood using the CMS tracker upgrade as a use-case.

Attachment Theory in Supervision: A Critical Incident Experience

Science.gov (United States)

Pistole, M. Carole; Fitch, Jenelle C.

2008-01-01

Critical incident experiences are a powerful source of counselor development (T. M. Skovholt & P. R. McCarthy, 1988a, 1988b) and are relevant to attachment issues. An attachment theory perspective of supervision is presented and applied to a critical incident case scenario. By focusing on the behavioral systems (i.e., attachment, caregiving, and…

Combustion-Powered Actuation for Dynamic Stall Suppression - Simulations and Low-Mach Experiments

Science.gov (United States)

Matalanis, Claude G.; Min, Byung-Young; Bowles, Patrick O.; Jee, Solkeun; Wake, Brian E.; Crittenden, Tom; Woo, George; Glezer, Ari

2014-01-01

An investigation on dynamic-stall suppression capabilities of combustion-powered actuation (COMPACT) applied to a tabbed VR-12 airfoil is presented. In the first section, results from computational fluid dynamics (CFD) simulations carried out at Mach numbers from 0.3 to 0.5 are presented. Several geometric parameters are varied including the slot chordwise location and angle. Actuation pulse amplitude, frequency, and timing are also varied. The simulations suggest that cycle-averaged lift increases of approximately 4% and 8% with respect to the baseline airfoil are possible at Mach numbers of 0.4 and 0.3 for deep and near-deep dynamic-stall conditions. In the second section, static-stall results from low-speed wind-tunnel experiments are presented. Low-speed experiments and high-speed CFD suggest that slots oriented tangential to the airfoil surface produce stronger benefits than slots oriented normal to the chordline. Low-speed experiments confirm that chordwise slot locations suitable for Mach 0.3-0.4 stall suppression (based on CFD) will also be effective at lower Mach numbers.

Critical experiments at Sandia National Laboratories

International Nuclear Information System (INIS)

Harms, Gary A.; Ford, John T.; Barber, Allison Delo

2010-01-01

Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE since the 1960's. Over this period, the research reactor facilities at Sandia have had a primary mission to provide appropriate nuclear radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor III (SPR-III), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The SPR-III is currently defueled. The SPR Facility (SPRF) has hosted a series of critical experiments. A purpose-built critical experiment was first operated at the SPRF in the late 1980's. This experiment, called the Space Nuclear Thermal Propulsion Critical Experiment (CX), was designed to explore the reactor physics of a nuclear thermal rocket motor. This experiment was fueled with highly-enriched uranium carbide fuel in annular water-moderated fuel elements. The experiment program was completed and the fuel for the experiment was moved off-site. A second critical experiment, the Burnup Credit Critical Experiment (BUCCX) was operated at Sandia in 2002. The critical assembly for this experiment was based on the assembly used in the CX modified to accommodate low-enriched pin-type fuel in water moderator. This experiment was designed as a platform in which the reactivity effects of specific fission product poisons could be measured. Experiments were carried out on rhodium, an important fission product poison. The fuel and assembly hardware for the BUCCX remains at Sandia and is available for future experimentation. The critical experiment currently in operation at the SPRF is the Seven Percent Critical Experiment (7uPCX). This experiment is designed to provide benchmark

Coretran/Vipre assembly critical power assessment against Nupec BWR experiments

Energy Technology Data Exchange (ETDEWEB)

Aounallah, Y. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

2001-07-01

This study has been performed, in the framework of the STARS project, to assess CORETRAN-01/VIPRE-02 code capability to predict critical heat flux conditions for BWR fuel assemblies. The assessment is based on comparisons of the code results with the NUPEC steady-state critical power measurements on full-scale assemblies tested under a range of flow conditions. Two assembly types were considered, the standard BWR 8 x 8 and the so-called ''high-burnup'' assembly, similar to GE-10. Code modelling options that have a significant impact on the results have been identified, along with code limitations. (author)

Management for nuclear power plants for safe operation

International Nuclear Information System (INIS)

Kueffer, K.

1981-01-01

This lecture covers management aspects which have an immediate bearing on safety and identifies the objectives and tasks of management which are required for safe operation of a nuclear power plant and is based on the Codes of Practice and Safety Guides of the IAEA as well as arrangements in use at the Swiss Nuclear Power Station Beznau. (orig./RW)

Review of battery powered embedded systems design for mission-critical low-power applications

Science.gov (United States)

Malewski, Matthew; Cowell, David M. J.; Freear, Steven

2018-06-01

The applications and uses of embedded systems is increasingly pervasive. Mission and safety critical systems relying on embedded systems pose specific challenges. Embedded systems is a multi-disciplinary domain, involving both hardware and software. Systems need to be designed in a holistic manner so that they are able to provide the desired reliability and minimise unnecessary complexity. The large problem landscape means that there is no one solution that fits all applications of embedded systems. With the primary focus of these mission and safety critical systems being functionality and reliability, there can be conflicts with business needs, and this can introduce pressures to reduce cost at the expense of reliability and functionality. This paper examines the challenges faced by battery powered systems, and then explores at more general problems, and several real-world embedded systems.

An inherently safe power reactor module

International Nuclear Information System (INIS)

Salerno, L.N.

1985-01-01

General Electric's long participation in liquid metal reactor technology has led to a Power Reactor Inherently Safe Module (PRISM) concept supported by DOE contract DE-AC06-85NE37937. The reactor module is sized to maximize inherent safety features. The small size allows factory fabrication, reducing field construction and field QA/QC labor, and allows safety to be demonstrated in full scale, to support a pre-licensed standard commercial product. The module is small enough to be placed underground, and can be combined with steam and electrical generating equipment to provide a complete electrical power producing plant in the range of 400-1200 MWe. Initial assessments are that the concept has the potential to be economically competitive with existing methods of power production used by the utility industry

Safety aspect of long-life small safe power reactors

International Nuclear Information System (INIS)

Zaki, S.; Sekimoto, H.

1995-01-01

Safety aspects of several design options of long-life small safe fast power reactors using nitride fuel and lead-bismuth as coolant are discussed. In the present study hypothetical accidents are simulated for these reactors, i.e., unprotected simultaneous ULOF (total loss of primary pumping system) and UTOP (rod run out transient over power) accidents, caused by the simultaneous withdrawal of all control rods. The proposed designs have some important safety characteristics as low reactivity swing (only 0.2-0.25$), and negative coolant void coefficient over whole burnup period. Effectively negative value of all components of reactivity during an accident is observed. The safety performances of the balance, pancake, and tall slender type of core, each of them satisfy reactivity and negative coolant void coefficient constraint, against the above accident are compared. The simulation results show that all of the design options can survive the above accidents without the help of reactor scram and without the need of operator actions. (author)

Critical experiments at Sandia National Laboratories

International Nuclear Information System (INIS)

Harms, G.A.; Ford, J.T.; Barber, A.D.

2011-01-01

Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE since the 1960's. Over this period, the research reactor facilities at Sandia have had a primary mission to provide appropriate nuclear radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor III (SPR-III), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The SPR-III is currently defueled. The SPR Facility (SPRF) has hosted a series of critical experiments. A purpose-built critical experiment was first operated at the SPRF in the late 1980's. This experiment, called the Space Nuclear Thermal Propulsion Critical Experiment (CX), was designed to explore the reactor physics of a nuclear thermal rocket motor. This experiment was fueled with highly-enriched uranium carbide fuel in annular water-moderated fuel elements. The experiment program was completed and the fuel for the experiment was moved off-site. A second critical experiment, the Burnup Credit Critical Experiment (BUCCX) was operated at Sandia in 2002. The critical assembly for this experiment was based on the assembly used in the CX modified to accommodate low-enriched pin-type fuel in water moderator. This experiment was designed as a platform in which the reactivity effects of specific fission product poisons could be measured. Experiments were carried out on rhodium, an important fission product poison. The fuel and assembly hardware for the BUCCX remains at Sandia and is available for future experimentation. The critical experiment currently in operation at the SPRF is the Seven Percent Critical Experiment (7uPCX). This experiment is designed to provide benchmark

Critical experiments at Sandia National Laboratories

Energy Technology Data Exchange (ETDEWEB)

Harms, G.A.; Ford, J.T.; Barber, A.D., E-mail: gaharms@sandia.gov [Sandia National Laboratories, Albuquerque, NM (United States)

2011-07-01

Sandia National Laboratories (SNL) has conducted radiation effects testing for the Department of Energy (DOE) and other contractors supporting the DOE since the 1960's. Over this period, the research reactor facilities at Sandia have had a primary mission to provide appropriate nuclear radiation environments for radiation testing and qualification of electronic components and other devices. The current generation of reactors includes the Annular Core Research Reactor (ACRR), a water-moderated pool-type reactor, fueled by elements constructed from UO2-BeO ceramic fuel pellets, and the Sandia Pulse Reactor III (SPR-III), a bare metal fast burst reactor utilizing a uranium-molybdenum alloy fuel. The SPR-III is currently defueled. The SPR Facility (SPRF) has hosted a series of critical experiments. A purpose-built critical experiment was first operated at the SPRF in the late 1980's. This experiment, called the Space Nuclear Thermal Propulsion Critical Experiment (CX), was designed to explore the reactor physics of a nuclear thermal rocket motor. This experiment was fueled with highly-enriched uranium carbide fuel in annular water-moderated fuel elements. The experiment program was completed and the fuel for the experiment was moved off-site. A second critical experiment, the Burnup Credit Critical Experiment (BUCCX) was operated at Sandia in 2002. The critical assembly for this experiment was based on the assembly used in the CX modified to accommodate low-enriched pin-type fuel in water moderator. This experiment was designed as a platform in which the reactivity effects of specific fission product poisons could be measured. Experiments were carried out on rhodium, an important fission product poison. The fuel and assembly hardware for the BUCCX remains at Sandia and is available for future experimentation. The critical experiment currently in operation at the SPRF is the Seven Percent Critical Experiment (7uPCX). This experiment is designed to provide

Critical power prediction by CATHARE2 of the OECD/NRC BFBT benchmark

Energy Technology Data Exchange (ETDEWEB)

Lutsanych, Sergii, E-mail: s.lutsanych@ing.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122, San Piero a Grado, Pisa (Italy); Sabotinov, Luben, E-mail: luben.sabotinov@irsn.fr [Institut for Radiological Protection and Nuclear Safety (IRSN), 31 avenue de la Division Leclerc, 92262 Fontenay-aux-Roses (France); D’Auria, Francesco, E-mail: francesco.dauria@dimnp.unipi.it [San Piero a Grado Nuclear Research Group (GRNSPG), University of Pisa, Via Livornese 1291, 56122, San Piero a Grado, Pisa (Italy)

2015-03-15

Highlights: • We used CATHARE code to calculate the critical power exercises of the OECD/NRC BFBT benchmark. • We considered both steady-state and transient critical power tests of the benchmark. • We used both the 1D and 3D features of the CATHARE code to simulate the experiments. • Acceptable prediction of the critical power and its location in the bundle is obtained using appropriate modelling. - Abstract: This paper presents an application of the French best estimate thermal-hydraulic code CATHARE 2 to calculate the critical power and departure from nucleate boiling (DNB) exercises of the International OECD/NRC BWR Fuel Bundle Test (BFBT) benchmark. The assessment activity is performed comparing the code calculation results with available in the framework of the benchmark experimental data from Japanese Nuclear Power Engineering Corporation (NUPEC). Two-phase flow calculations on prediction of the critical power have been carried out both in steady state and transient cases, using one-dimensional and three-dimensional modelling. Results of the steady-state critical power tests calculation have shown the ability of CATHARE code to predict reasonably the critical power and its location, using appropriate modelling.

Criticality safety of low-density storage arrays

International Nuclear Information System (INIS)

Bauer, T. H.; Nuclear Engineering Division

2005-01-01

This paper proposes a straightforward bounding method for the criticality safety analysis of fissionable materials configured into large arrays of standard containers. While criticality-safe storage limits have been well established for single containers, even under flooded conditions, it is also necessary to rule out any potential for criticality arising from neutronic interactions among multiple containers that might build up over long distances in a large array. Traditionally, the array problem has been approached by individual Monte Carlo analyses of explicit arrangements of single units and their surroundings. Deemphasizing specific configurations, the present technique takes advantage of low average density of fissionable material in typical storage arrays to separate neutron interactions that take place in the neutron's 'birth unit' from subsequent interactions in a dilute array. Numerous explicit Monte Carlo analyses show that array effects may be conservatively calculated by analyses that homogenize fissionable contents and depend only on the overall array shape, size, and reflective boundary

Criticality safety of low-density storage arrays

International Nuclear Information System (INIS)

Bauer, T.H.

1996-01-01

This paper proposes a straightforward bounding method for the criticality safety analysis of fissionable materials configured into large arrays of standard containers. While criticality-safe storage limits have been well established for single containers, even under flooded conditions, it is also necessary to rule out any potential for criticality arising from neutronic interactions among multiple containers that might build up over long distances in a large array. Traditionally, the array problem has been approached by individual Monte Carlo analyses of explicit arrangements of single units and their surroundings. Deemphasizing specific configurations, the present technique takes advantage of low average density of fissionable material in typical storage arrays to separate neutron interactions that take place in the neutron's open-quotes birth unitclose quotes from subsequent interactions in a dilute array. Numerous explicit Monte Carlo analyses show that array effects may be conservatively calculated by analyses that homogenize fissionable contents and depend only on the overall array shape, size, and reflective boundary

Heavy water critical experiments on plutonium lattice

International Nuclear Information System (INIS)

Miyawaki, Yoshio; Shiba, Kiminori

1975-06-01

This report is the summary of physics study on plutonium lattice made in Heavy Water Critical Experiment Section of PNC. By using Deuterium Critical Assembly, physics study on plutonium lattice has been carried out since 1972. Experiments on following items were performed in a core having 22.5 cm square lattice pitch. (1) Material buckling (2) Lattice parameters (3) Local power distribution factor (4) Gross flux distribution in two region core (5) Control rod worth. Experimental results were compared with theoretical ones calculated by METHUSELAH II code. It is concluded from this study that calculation by METHUSELAH II code has acceptable accuracy in the prediction on plutonium lattice. (author)

Experiments on Critical Heat Flux for CAREM -25 Reactor

International Nuclear Information System (INIS)

Mazufri, C.M

2000-01-01

The prediction of critical heat flux (CHF) in rod bundles of light water reactors is basically performed with the aid of empirical correlations derived from experimental data.Many CHF correlations have been proposed and are widely used in the analysis of the thermal margin during normal operation, transient, and accident conditions.Correlations found in the open literature are not sufficiently verified for the thermal hydraulic conditions that appear in the CAREM core under normal operation: high pressure, low flow, and low qualities.To compensate this deficiency, an experimental investigation on CHF in such thermal-hydraulic conditions was carried out.The experiments have been performed in the Institute of Physics and Power Engineering of Russian Federation.A short description of facilities, details of the experimental program and some preliminary results obtained are presented in this work

Management of nuclear power plants for safe operation

International Nuclear Information System (INIS)

Kueffer, K.

1980-01-01

This lecture covers management aspects which have an immediate bearing on safety and identifies the objectives and tasks of management which are required for safe operation of a nuclear power plant and is based on the Codes of Practice and Safety Guides of the IAEA as well as arrangements in use at the Swiss Nuclear Power Station Beznau. This lecture - discusses the factors to be considered in structuring the operating organization, the support to be provided to plant management, the services and facilities needed and the management system for assuring the safety tasks are performed - describes the responsibilities of plant management and operating organization - outlines the requirements for recruitment, training and retraining as well as qualification and authorization of personnel - describes the programmes for maintenance, testing, examination, inspection, radiological protection, quality assurance, waste management, fuel management, emergency arrangement and security - describes the development of plant operating procedures including procedures to protect the personnel - outlines the requirements for initial and subsequent operation - describes the importance for evaluation and feedback of operating experience - describes the procedures for changes in hardware, procedures and set points - outlines the information flow and the requirements in reference to records and reports. (orig./RW)

Efficient Algorithm and Architecture of Critical-Band Transform for Low-Power Speech Applications

Directory of Open Access Journals (Sweden)

Gan Woon-Seng

2007-01-01

Full Text Available An efficient algorithm and its corresponding VLSI architecture for the critical-band transform (CBT are developed to approximate the critical-band filtering of the human ear. The CBT consists of a constant-bandwidth transform in the lower frequency range and a Brown constant- transform (CQT in the higher frequency range. The corresponding VLSI architecture is proposed to achieve significant power efficiency by reducing the computational complexity, using pipeline and parallel processing, and applying the supply voltage scaling technique. A 21-band Bark scale CBT processor with a sampling rate of 16 kHz is designed and simulated. Simulation results verify its suitability for performing short-time spectral analysis on speech. It has a better fitting on the human ear critical-band analysis, significantly fewer computations, and therefore is more energy-efficient than other methods. With a 0.35 m CMOS technology, it calculates a 160-point speech in 4.99 milliseconds at 234 kHz. The power dissipation is 15.6 W at 1.1 V. It achieves 82.1 power reduction as compared to a benchmark 256-point FFT processor.

Implementation of Industry Experience at Nuclear Power Plant Krsko

International Nuclear Information System (INIS)

Heruc, Z.; Kavsek, D.

2002-01-01

Being a standalone comparatively small unit NPP Krsko has adopted a business philosophy to incorporate industry experience into its daily operations. The continuos and safe operation of the unit is supported through feedback from other utilities (lessons learned) and equipment vendors and manufacturers. A permanent proactive approach in monitoring the international nuclear technology practices, standards changes and improvements, and upon feasibility review, introducing them into processes and equipment upgrades, is applied. As a member of the most important international integrations, NPP Krsko has benefited from the opportunity of sharing its experience with others (World Association of Nuclear Operators -WANO, Institute of Nuclear Power Operations - INPO, International Atomic Energy Agency - IAEA, Nuclear Operations Maintenance Information Service - NOMIS, Nuclear Maintenance Experience Exchange - NUMEX, Electric Power Research Institute - EPRI, Westinghouse Owners Group - WOG, etc.). Voluntary activities and good practices related to safety are achieved by international missions (IAEA Assessment of Safety Significant Events Team - ASSET, IAEA Operational Safety Review Team - OSART, WANO Peer Review, International Commission for Independent Safety Analysis - ICISA) and operating experience exchange programs through international organizations. These missions are promoting the highest levels of excellence in nuclear power plant operation, maintenance and support. With time, the practices described in this paper presented themselves as most contributing to safe and reliable operation of our power plant and at the same time supporting cost optimization making it a viable and reliable source of electrical energy in the more and more deregulated market. (author)

Critical experiments on low-enriched uranium oxide system with H/U=1.25

International Nuclear Information System (INIS)

Oh, I.; Rothe, R.E.; Tuck, G.

1982-01-01

Fifteen (15) critical experiments were performed on a horizontal split table machine using 4.48%-enriched sup(235)U uranium oxide(U 3 O 8 ). The oxide was compacted to a density of 4.68g/cm 3 and placed in 152 mm cubical aluminum cans. Water was added to achive an H/U of 1.25. Various arrays of oxide cans were distributed on each half of the split table, and the separation between halves reduced until criticality occurred. The critical table separation varied from 3.59 mm to 18.40 mm. Twelve (12) experiments required the addition of a high-enriched(-93 %sup(235)U) metal or solution driver to achieve criticality. These experiments were performed in a plastic, concrete, or thin steel reflector. Three additional experiments in the plastic reflector contained either 9.3-mm- or 24.3-mm-thick plastic moderator material between the oxide cans and did not require a driver to achieve criticality. Critical uranium driver masses ranged from 9.999 kg to 14.000 kg (solution driver), and from 25.378 kg to 29.278 kg (metal driver) for 5X5X5 arrays of uranium oxide cans. Always, one or four of these 125 cans had to be removed to make room for the drivers. Therefore, the uranium oxide masses used were 1823.8 kg and 1863.5 kg. For the moderated experiments, the uranium oxide mass ranged between 574.4 kg and 1210.0 kg. (Author)

A short review of critical experiments performed at the Kurchatov Institute

International Nuclear Information System (INIS)

Gagarinski, A.Yu.; Glushkov, Y.S.; Ponomarev-Stepnoi, N.N.

1997-01-01

Since the 1950s, the Institute of Atomic Energy (now the Russian Research Center Kurchatov Institute) has investigated nuclear reactors intended for various purposes. A summary of the present state of these assemblies is given in an attachment to the paper. A second attachment provides a brief description of critical experiments for small nuclear power systems intended for decentralized power generation. The critical assemblies for these experiments were moderated by water and zirconium hydride, and fuel elements ranged in enrichment from 5% to 95% uranium 235. 7 refs

A short review of critical experiments performed at the Kurchatov Institute

Energy Technology Data Exchange (ETDEWEB)

Gagarinski, A.Yu.; Glushkov, Y.S.; Ponomarev-Stepnoi, N.N. [Kurchatov Institute (Russian Federation)

1997-06-01

Since the 1950s, the Institute of Atomic Energy (now the Russian Research Center Kurchatov Institute) has investigated nuclear reactors intended for various purposes. A summary of the present state of these assemblies is given in an attachment to the paper. A second attachment provides a brief description of critical experiments for small nuclear power systems intended for decentralized power generation. The critical assemblies for these experiments were moderated by water and zirconium hydride, and fuel elements ranged in enrichment from 5% to 95% uranium 235. 7 refs.

MOCA: A Low-Power, Low-Cost Motion Capture System Based on Integrated Accelerometers

Directory of Open Access Journals (Sweden)

Elisabetta Farella

2007-01-01

Full Text Available Human-computer interaction (HCI and virtual reality applications pose the challenge of enabling real-time interfaces for natural interaction. Gesture recognition based on body-mounted accelerometers has been proposed as a viable solution to translate patterns of movements that are associated with user commands, thus substituting point-and-click methods or other cumbersome input devices. On the other hand, cost and power constraints make the implementation of a natural and efficient interface suitable for consumer applications a critical task. Even though several gesture recognition solutions exist, their use in HCI context has been poorly characterized. For this reason, in this paper, we consider a low-cost/low-power wearable motion tracking system based on integrated accelerometers called motion capture with accelerometers (MOCA that we evaluated for navigation in virtual spaces. Recognition is based on a geometric algorithm that enables efficient and robust detection of rotational movements. Our objective is to demonstrate that such a low-cost and a low-power implementation is suitable for HCI applications. To this purpose, we characterized the system from both a quantitative point of view and a qualitative point of view. First, we performed static and dynamic assessment of movement recognition accuracy. Second, we evaluated the effectiveness of user experience using a 3D game application as a test bed.

Study on expansion power recovery in CO2 trans-critical cycle

International Nuclear Information System (INIS)

Tian Hua; Ma Yitai; Li Minxia; Wang Wei

2010-01-01

Due to the ozone depletion potential and global warming potential of CFCs and HCFCs, CO 2 is considered as most potential alternative refrigerant. However, there are serious throttle losses and low system efficiency to CO 2 trans-critical cycle because of its low critical temperature and high operating pressure. The aim of this paper is to design an expander to recover expansion power in CO 2 trans-critical cycle. The theoretical analysis and calculation show that 14-23% of input power of compressor can be recovered. A prototype of rolling piston expander is designed and manufactured and its test facility is established. The test facility consists of CO 2 trans-critical cycle, the expander, the chilling water system and the cooling water system. The experimental results show that the recovery ratio and expander efficiency are affected by rotational speed, inlet temperature and mass flow of expander. The highest recovery ratio can reach to 0.145, which means 14.5% of input power of compressor can be recovered. The expander efficiency can reach to 45%.

Application of digital solutions to help the safe and efficient operation of nuclear power plants

International Nuclear Information System (INIS)

Ortega P, F.; Fernandez F, S.

2017-09-01

In the search for excellence, the emergence of solutions to digitize nuclear power plants is an opportunity to optimize the operation and safety of them. The new technologies available today in the market, applied under a global vision of the operation, can contribute to the excellent operation of nuclear power plants in terms of efficiency and effectiveness. Tecnatom has a long experience in various areas related to the operation of the plants, giving the aforementioned global vision, essential to develop global solutions that pursue the safe and efficient operation of the operation. (Author)

Extreme low-power mixed signal IC design

CERN Document Server

Tajalli, Armin

2010-01-01

This book describes a completely novel class of techniques for designing ultra-low-power integrated circuits (ICs). In many applications such as battery operated systems and battery-less (energy-scavenging) systems, power dissipation is a critical parameter. As a result, there is a growing demand for reducing the power (energy) consumption in ICs to extremely low levels, not achievable by using classical ""subthreshold CMOS"" techniques. This book introduces a new family of ""subthreshold circuits"" called ""source-coupled circuits"". This family of circuits can be used for implementing digita

Commercial experience with facility deactivation to safe storage

Energy Technology Data Exchange (ETDEWEB)

Sype, T.T. [Sandia National Labs., Albuquerque, NM (United States); Fischer, S.R. [Los Alamos National Lab., NM (United States); Lee, J.H. Jr.; Sanchez, L.C.; Ottinger, C.A.; Pirtle, G.J. [Sandia National Labs., Albuquerque, NM (United States)

1995-09-01

The Department of Energy (DOE) has shutdown many production reactors; the Department has begun a major effort to also shutdown a wide variety of other nuclear facilities. Because so many facilities are being closed, it is necessary to place many of them into a safe- storage status, i.e., deactivation, before conducting decommissioning- for perhaps as long as 20 years. The challenge is to achieve this safe-storage condition in a cost-effective manner while remaining in compliance with applicable regulations. The DOE Office of Environmental Management, Office of Transition and Management, commissioned a lessons-learned study of commercial experience with safe storage and decommissioning. Although the majority of the commercial experience has been with reactors, many of the lessons learned presented in this document can provide insight into transitioning challenges that Will be faced by the DOE weapons complex.

Commercial experience with facility deactivation to safe storage

International Nuclear Information System (INIS)

Sype, T.T.; Fischer, S.R.; Lee, J.H. Jr.; Sanchez, L.C.; Ottinger, C.A.; Pirtle, G.J.

1995-09-01

The Department of Energy (DOE) has shutdown many production reactors; the Department has begun a major effort to also shutdown a wide variety of other nuclear facilities. Because so many facilities are being closed, it is necessary to place many of them into a safe- storage status, i.e., deactivation, before conducting decommissioning- for perhaps as long as 20 years. The challenge is to achieve this safe-storage condition in a cost-effective manner while remaining in compliance with applicable regulations. The DOE Office of Environmental Management, Office of Transition and Management, commissioned a lessons-learned study of commercial experience with safe storage and decommissioning. Although the majority of the commercial experience has been with reactors, many of the lessons learned presented in this document can provide insight into transitioning challenges that Will be faced by the DOE weapons complex

Operating manual for the critical experiments facility

International Nuclear Information System (INIS)

1986-01-01

The operation of the Critical Experiments Facility (CEF) requires careful attention to procedures in order that all safety precautions are observed. Since an accident could release large amounts of radioactivity, careful operation and strict enforcement of procedures are necessary. To provide for safe operation, detailed procedures have been written for all phases of the operation of this facility. The CEF operating procedures are not to be construed to constitute a part ofthe Technical Specifications. In the event of any discrepancy between the information given herein and the Technical Specifications, limits set forth in the Technical Specifications apply. All normal and most emergency operation conditions are covered by procedures presented in this manual. These procedures are designed to be followed by the operating personnel. Strict adherence to these procedures is expected for the following reasons. (1) To provide a standard, safe method of performing all operations, the procedures were written by reactor engineers experienced in supervising the operation of reactors and were reviewed by an organization with over 30 years of reactor operating experience. (2) To have an up-to-date description of operating techniques available at all times for reference and review, it is necessary that the procedures be written

Operating manual for the critical experiments facility

Energy Technology Data Exchange (ETDEWEB)

1986-01-01

The operation of the Critical Experiments Facility (CEF) requires careful attention to procedures in order that all safety precautions are observed. Since an accident could release large amounts of radioactivity, careful operation and strict enforcement of procedures are necessary. To provide for safe operation, detailed procedures have been written for all phases of the operation of this facility. The CEF operating procedures are not to be construed to constitute a part ofthe Technical Specifications. In the event of any discrepancy between the information given herein and the Technical Specifications, limits set forth in the Technical Specifications apply. All normal and most emergency operation conditions are covered by procedures presented in this manual. These procedures are designed to be followed by the operating personnel. Strict adherence to these procedures is expected for the following reasons. (1) To provide a standard, safe method of performing all operations, the procedures were written by reactor engineers experienced in supervising the operation of reactors and were reviewed by an organization with over 30 years of reactor operating experience. (2) To have an up-to-date description of operating techniques available at all times for reference and review, it is necessary that the procedures be written.

Basic experiments of reactor physics using the critical assembly TCA

International Nuclear Information System (INIS)

Obara, Toru; Igashira, Masayuki; Sekimoto, Hiroshi; Nakajima, Ken; Suzaki, Takenori.

1994-02-01

This report is based on lectures given to graduate students of Tokyo Institute of Technology. It covers educational experiments conducted with the Tank-Type Critical Assembly (TCA) at Japan Atomic Energy Research Institute in July, 1993. During this period, the following basic experiments on reactor physics were performed: (1) Critical approach experiment, (2) Measurement of neutron flux distribution, (3) Measurement of power distribution, (4) Measurement of fuel rod worth distribution, (5) Measurement of safety sheet worth by the rod drop method. The principle of experiments, experimental procedure, and analysis of results are described in this report. (author)

Critically safe volume vacuum pickup for use in wet or dry cleanup of radioactive enclosures

International Nuclear Information System (INIS)

Zeren, J.D.

1993-01-01

A physical compact vacuum pickup device of critically safe volume and geometric shape is provided for use in radioactive enclosures, such as a small glove box, to facilitate manual cleanup of either wet or dry radioactive material. The device is constructed and arranged so as to remain safe when filled to capacity with plutonium-239 oxide. Two fine mesh filter bags are supported on the exterior of a rigid fine mesh stainless steel cup. This assembly is sealed within, and spaced from, the interior walls of a stainless steel canister. An air inlet communicates with the interior of the canister. A modified conventional vacuum head is physically connected to, and associated with, the interior of the mesh cup. The volume of the canister, as defined by the space between the mesh cup and the interior walls of the canister, forms a critically safe volume and geometric shape for dry radioactive particles that are gathered within the canister. A critically safe liquid volume is maintained by operation of a suction terminating float valve, and/or by operation of redundant vacuum check/liquid drain valves and placement of the air inlet. 5 figures

UAV Low Altitude Photogrammetry for Power Line Inspection

Directory of Open Access Journals (Sweden)

Yong Zhang

2017-01-01

Full Text Available When the distance between an obstacle and a power line is less than the discharge distance, a discharge arc can be generated, resulting in the interruption of power supplies. Therefore, regular safety inspections are necessary to ensure the safe operation of power grids. Tall vegetation and buildings are the key factors threatening the safe operation of extra high voltage transmission lines within a power line corridor. Manual or laser intensity direction and ranging (LiDAR based inspections are time consuming and expensive. To make safety inspections more efficient and flexible, a low-altitude unmanned aerial vehicle (UAV remote-sensing platform, equipped with an optical digital camera, was used to inspect power line corridors. We propose a semi-patch matching algorithm based on epipolar constraints, using both the correlation coefficient (CC and the shape of its curve to extract three dimensional (3D point clouds for a power line corridor. We use a stereo image pair from inter-strip to improve power line measurement accuracy by transforming the power line direction to an approximately perpendicular to epipolar line. The distance between the power lines and the 3D point cloud is taken as a criterion for locating obstacles within the power line corridor automatically. Experimental results show that our proposed method is a reliable, cost effective, and applicable way for practical power line inspection and can locate obstacles within the power line corridor with accuracy better than ±0.5 m.

Refinement of criticality and breeding parameters by means of experiments on a series of critical assemblies

International Nuclear Information System (INIS)

Golubev, V.I.; Dulin, V.A.; Kazanskij, Yu.A.; Mamontov, V.M.; Mozhaev, V.K.; Sidorov, G.I.

1980-01-01

A programme of measurements was performed on a number of critical assemblies with the aim of obtaining reliable experimental data under conditions approximating the simplest calculation model. To this end the neutron balance at the centres of the BFS-31, BFS-33, BFS-35, BFS-38, KBR-3 and KBR-7 critical assemblies was investigated. These assemblies contained central inserts made of uranium dioxide (BFS-33), natural uranium oxide and plutonium metal (BFS-31), natural uranium and plutonium metal (BFS-38), 90% enriched metallic uranium and stainless steel (KBR-3) and enriched uranium dioxide and nickel (KBR-7). The composition of the inserts was such that Ksub(infinite)=1. The K + values, the ratios of the reaction rates of the principal raw material and fissionable isotopes and the reactivity coefficients of a number of materials were measured in the inserts. The components of the breeding coefficient were measured at the centre of the BFS-39 critical assembly which simulates a power reactor (simplest composition with low- and high-enrichment zones and no control mechanism). The authors describe briefly the critical assemblies, the methods of measurement and calculation and methods of correcting for differences between the calculation model and the conditions under which the measurements were performed and compare the results of the experiments with the corresponding theoretical values obtained using various systems of group constants. In their latest versions, the group constants derived from different sets of integral experiments describe the experimental data much better than was previously possible. The deviations which occur in the predicted criticality and breeding parameters using different versions of the constants essentially reflect the difference in the results of the sets of integral experiments that were used for the group constants. (author)

Cadmium-emitter self-powered thermal neutron detector performance characterization & reactor power tracking capability experiments performed in ZED-2

Energy Technology Data Exchange (ETDEWEB)

LaFontaine, M.W., E-mail: physics@execulink.com [LaFontaine Consulting, Kitchener, Ontario (Canada); Zeller, M.B. [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada); Nielsen, K. [Royal Military College of Canada, SLOWPOKE-2 Reactor, Kingston, Ontario (Canada)

2014-07-01

Cadmium-emitter self-powered thermal neutron flux detectors (SPDs), are typically used for flux monitoring and control applications in low temperature, test reactors such as the SLOWPOKE-2. A collaborative program between Atomic Energy of Canada, academia (Royal Military College of Canada (RMCC)) and industry (LaFontaine Consulting) was initiated to characterize the incore performance of a typical Cd-emitter SPD; and to obtain a definitive measure of the capability of the detector to track changes in reactor power in real time. Prior to starting the experiment proper, Chalk River Laboratories' ZED-2 was operated at low power (5 watts nominal) to verify the predicted moderator critical height. Test measurements were then performed with the vertical center of the SPD emitter positioned at the vertical mid-plane of the ZED-2 reactor core. Measurements were taken with the SPD located at lattice position L0 (near center), and repeated at lattice position P0 (in D{sub 2}O reflector). An ionization chamber (part of the ZED-2 control instrumentation) monitored reactor power at a position located on the south side of the outside wall of the reactor's calandria. These experiments facilitated measurement of the absolute thermal neutron sensitivity of the subject Cd-emitter SPD, and validated the power tracking capability of said SPD. Procedural details of the experiments, data, calculations and associated graphs, are presented and discussed. (author)

Determination of "safe" and "critical" nanoparticles exposure to welders in a workshop.

Science.gov (United States)

Gomes, J F; Miranda, R M

2017-01-01

The present study examined consequences of "safe" versus "critical" exposure to nanoparticles (NP) released during welding operations. With this aim in mind, a set of measurements regarding NP emissions was undertaken in a workshop during welding by metal active gas of carbon steel using different mixtures of argon (Ar) and carbon dioxide (CO 2 ) as well as different process parameters which might influence emission of (NP). If these measurements were conducted in several locations away from the welding sources, the graphical representation of the obtained observations with time enabled definition of "safe" and "critical" regions within a welding workshop in terms of welder's exposure. This information may be combined with the results of risk analysis derived by control banding and helps to categorize the sites where regulatory measures such as operation containment or dedicated exhaust ventilation need to be implemented.

THE SECURITY AND CRITICAL LEVELS OF PHYSICAL ACTIVITY FOR TRAINED AND UNTRAINED PERSONS IN MUSCLE PERFORMANCE POWER ORIENTATION.

Science.gov (United States)

Chernozub, A A

The paper studied the problem of finding the optimal methodology for determining the safety and critical load conditions for the body trained and untrained people in the process of training the force pool. It was found that for trained individuals who have a sufficient level of adaptation to the power load, the use of “standard” modes of operation in the course of employment by fitness power safely. However, the problematic issue is that to the untrained troops, it is almost impossible to determine the safe load parameters using conventional techniques, which are mainly used in cyclic sports. Thus, the solution to this problem lies in the fact that using the integral method for estimating the value of power loads and a computer program for determining the relative weight of the index weights, safety and critical load parameters were calculated for untrained persons. At the same time, studied the biochemical parameters of blood (testosterone, cortisol, and lactate dehydrogenase activity) fixed after exercise, compared with the state of rest, confirmed our calculations clearly enough.

What's so critical about Critical Neuroscience? Rethinking experiment, enacting critique.

Science.gov (United States)

Fitzgerald, Des; Matusall, Svenja; Skewes, Joshua; Roepstorff, Andreas

2014-01-01

In the midst of on-going hype about the power and potency of the new brain sciences, scholars within "Critical Neuroscience" have called for a more nuanced and sceptical neuroscientific knowledge-practice. Drawing especially on the Frankfurt School, they urge neuroscientists towards a more critical approach-one that re-inscribes the objects and practices of neuroscientific knowledge within webs of social, cultural, historical and political-economic contingency. This paper is an attempt to open up the black-box of "critique" within Critical Neuroscience itself. Specifically, we argue that limiting enactments of critique to the invocation of context misses the force of what a highly-stylized and tightly-bound neuroscientific experiment can actually do. We show that, within the neuroscientific experiment itself, the world-excluding and context-denying "rules of the game" may also enact critique, in novel and surprising forms, while remaining formally independent of the workings of society, and culture, and history. To demonstrate this possibility, we analyze the Optimally Interacting Minds (OIM) paradigm, a neuroscientific experiment that used classical psychophysical methods to show that, in some situations, people worked better as a collective, and not as individuals-a claim that works precisely against reactionary tendencies that prioritize individual over collective agency, but that was generated and legitimized entirely within the formal, context-denying conventions of neuroscientific experimentation. At the heart of this paper is a claim that it was precisely the rigors and rules of the experimental game that allowed these scientists to enact some surprisingly critical, and even radical, gestures. We conclude by suggesting that, in the midst of large-scale neuroscientific initiatives, it may be "experiment", and not "context", that forms the meeting-ground between neuro-biological and socio-political research practices.

Exponential and Critical Experiments Vol. II. Proceedings of the Symposium on Exponential and Critical Experiments

International Nuclear Information System (INIS)

1964-01-01

In September 1963 the International Atomic Energy Agency organized the Symposium on Exponential and Critical Experiments in Amsterdam, Netherlands, at the invitation of the Government of the Netherlands. The Symposium enabled scientists from Member States to discuss the results of such experiments which provide the physics data necessary for the design of power reactors. Great advances made in recent years in this field have provided scientists with highly sophisticated and reliable experimental and theoretical methods. This trend is reflected in the presentation, at the Symposium, of many new experimental techniques resulting in more detailed and accurate information and a reduction of costs. Both the number of experimental parameters and their range of variation have been extended, and a closer degree of simulation of the actual power reactor has been achieved, for example, by means of high temperature critical assemblies. Basic types of lattices have continued to be the objective of many investigations, and extensive theoretical analyses have been carried out to provide a more thorough understanding of the neutron physics involved. Twenty nine countries and 3 international organizations were represented by 198 participants. Seventy one papers were presented. These numbers alone show the wide interest which the topic commands in the field of reactor design. We hope that this publication, which includes the papers presented at the Symposium and a record of the discussions, will prove useful as a work of reference to scientists working in this field

Analysis of critical paths for schedule control of nuclear power projects

International Nuclear Information System (INIS)

Shi Liangmin; Ma Limin; Fan Kai

2005-01-01

Study on the critical paths for the schedule control of nuclear power projects has been performed for reactor M310, based on the experiences from Daya Bay project and Ling Ao project. The study shows that the critical paths for the nuclear power project are from NI civil work, NI erection, commissioning of single systems directly serving the CFT to the joint-test. For NI civil work, the critical path is the main civil work of the reactor building, pre-stressing, handover of rooms for important areas, and key CW-erection interfaces; there are four critical paths for NI erection; For startup, two stages can be identified: commissioning of 16 single systems directly serving the CFT and joint-test. (authors)

High-flow, low-head pumps provide safe passage for Pacific salmon

International Nuclear Information System (INIS)

Anon

2004-01-01

The installation of 29 ultra-low head, high capacity submersible pump and auxiliary equipment at the Rocky Reach Dam in Washington State to allow juvenile salmon safe passage on their journey down the Columbia River to the Pacific Ocean is described. The reputed cost of the project is US$160 million; its purpose is to get juvenile salmon safely around the Rocky Reach Dam without interfering with the dam's original mission of generating electric power. The project is the most expensive fish bypass on any Columbia River dam. Getting the salmon safely around the dam is intended to reduce the impact of hydroelectric power projects on the basin's salmon stocks which are now estimated at less than 10 per cent of their historic size, despite major hatchery programs. The Columbia River has the second largest volume flow of any river in the United States, and millions of people depend on it for employment in water-related industries, and for transportation. The new horizontally installed propeller pump was developed by ITT Flygt; it utilizes planetary gear reduced to match the motor speed with the propeller rpm. Each 90 kW propeller pump has a flow rate of seven cubic meters per second at a head of 0.55 metres. The auxiliary equipment includes 10 racks of flap gates to prevent reverse flow, electric controls, remote supervision, testing, installation and maintenance facilities. It is anticipated that the new bypass will allow the Chelan County Public Utility Department, owners of the facility, to phase out all current spills, except for a 16 per cent spill for 40 days each spring for Sockeye salmon which tend to travel too deep to use the bypass. Prior to installation of this new facility, 60 to 70 per cent of average daily flow in the spring and summer had to be sacrificed to accommodate all species of salmon and steelhead, with corresponding losses of power generating capacity

MCNPTM criticality primer and training experiences

International Nuclear Information System (INIS)

Briesmeister, J.; Forster, R.A.; Busch, R.

1995-01-01

With the closure of many experimental facilities, the nuclear criticality safety analyst is increasingly required to rely on computer calculations to identify safe limits for the handling and storage of fissile materials. However, the analyst may have little experience with the specific codes available at his or her facility. Usually, the codes are quite complex, black boxes capable of analyzing numerous problems with a myriad of input options. Documentation for these codes is designed to cover all the possible configurations and types of analyses but does not give much detail on any particular type of analysis. For criticality calculations, the user of a code is primarily interested in the value of the effective multiplication factor for a system (k eff ). Most codes will provide this, and truckloads of other information that may be less pertinent to criticality calculations. Based on discussions with code users in the nuclear criticality safety community, it was decided that a simple document discussing the ins and outs of criticality calculations with specific codes would be quite useful. The Transport Methods Group, XTM, at Los Alamos National Laboratory (LANL) decided to develop a primer for criticality calculations with their Monte Carlo code, MCNP. This was a joint task between LANL with a knowledge and understanding of the nuances and capabilities of MCNP and the University of New Mexico with a knowledge and understanding of nuclear criticality safety calculations and educating first time users of neutronics calculations. The initial problem was that the MCNP manual just contained too much information. Almost everything one needs to know about MCNP can be found in the manual; the problem is that there is more information than a user requires to do a simple k eff calculation. The basic concept of the primer was to distill the manual to create a document whose only focus was criticality calculations using MCNP

Educational reactor-physics experiments with the critical assemble TCA

Energy Technology Data Exchange (ETDEWEB)

Tsutsui, Hiroaki; Okubo, Masaaki; Igashira, Masayuki [Tokyo Inst. of Tech. (Japan); Horiki, Oichiro; Suzaki, Takenori

1997-10-01

The Tank-Type Critical Assembly (TCA) of Japan Atomic Energy Research Institute is research equipment for light water reactor physics. In the present report, the lectures given to the graduate students of Tokyo Institute of Technology who participated in the educational experiment course held on 26-30 August at TCA are rearranged to provide useful information for those who will implement educational basic experiments with TCA in the future. This report describes the principles, procedures, and data analyses for (1) Critical approach and Exponential experiment, (2) Measurement of neutron flux distribution, (3) Measurement of power distribution, (4) Measurement of fuel rod worth distribution, and (5) Measurement of safety plate worth by the rod drop method. (author)

Educational reactor-physics experiments with the critical assembly TCA

International Nuclear Information System (INIS)

Tsutsui, Hiroaki; Okubo, Masaaki; Igashira, Masayuki; Horiki, Oichiro; Suzaki, Takenori.

1997-10-01

The Tank-Type Critical Assembly (TCA) of Japan Atomic Energy Research Institute is research equipment for light water reactor physics. In the present report, the lectures given to the graduate students of Tokyo Institute of Technology who participated in the educational experiment course held on 26-30 August at TCA are rearranged to provide useful information for those who will implement educational basic experiments with TCA in the future. This report describes the principles, procedures, and data analyses for 1) Critical approach and Exponential experiment, 2) Measurement of neutron flux distribution, 3) Measurement of power distribution, 4) Measurement of fuel rod worth distribution, and 5) Measurement of safety plate worth by the rod drop method. (author)

Main corrective measures in an early phase of nuclear power plants’ preparation for safe long term operation

Energy Technology Data Exchange (ETDEWEB)

Krivanek, Robert, E-mail: r.krivanek@iaea.org [International Atomic Energy Agency (IAEA), Department of Nuclear Safety and Security, Operational Safety Section, Vienna 1400 (Austria); Fiedler, Jan, E-mail: fiedler@fme.vutbr.cz [University of Technology Brno, Faculty of Mechanical Engineering, Energy Institute, Technická 2896/2, 616 69 Brno (Czech Republic)

2017-05-15

Highlights: • Results of SALTO missions provide the most important issues for safe long term operation (LTO) of nuclear power plants. • The most important technical corrective measures in an early phase of preparation for safe LTO are described. • Their satisfactory resolution creates a basis for further activities to demonstrate preparedness for safe LTO. - Abstract: This paper presents the analysis of main technical deficiencies of nuclear power plants (NPPs) in preparedness for safe long term operation (LTO) and the main corrective measures in an early phase of preparation for safe LTO of NPPs. It focuses on technical aspects connected with management of physical ageing of NPP structures, systems and components (SSCs). It uses as a basis results of IAEA SALTO missions performed between 2005 and 2016 (see also paper NED8805 in Nuclear Engineering and Design in May 2016) and the personal experiences of the authors with preparation of NPPs for safe LTO. This paper does not discuss other important aspects of safe LTO of NPPs, e.g. national nuclear energy policies, compliance of NPPs with the latest international requirements on design, obsolescence, environmental impact and economic aspects of LTO. Chapter 1 provides a brief introduction of the current status of the NPP’ fleet in connection with LTO. Chapter 2 provides an overview of SALTO peer review service results with a focus on deficiencies related to physical ageing of safety SSCs and a demonstration that SSCs will perform their safety function during the intended period of LTO. Chapter 3 discusses the main corrective measures which NPPs typically face during the preparation for demonstration of safe LTO. Chapter 4 summarizes the current status of the NPP’ fleet in connection with LTO and outlines further steps needed in preparation for safe LTO.

Criticality safety of low-density storage arrays

International Nuclear Information System (INIS)

Bauer, T.H.

1996-01-01

This note proposes a straightforward and simple method for the criticality safety analysis of fissionable materials configured into large arrays of standard containers. While criticality-safe storage limits have been well-established for standard containers--even under flooded conditions, it is also necessary to rule out the potential for criticality arising from neutronic interactions among multiple containers that might build up over long distances in a large array. Traditionally, the array problem has been approached by individual Monte Carlo analyses of explicit arrangements of single units and their surroundings. Here, the authors show how multiple Monte Carlo analyses can be usefully combined for wide-ranging general application. The technique takes advantage of low average density of fissionable material in typical storage arrays to separate neutron interactions that take place in the neutron's ''birth unit'' from subsequent interactions in a highly dilute array. Effects of array size, in particular, are conservatively calculated by straightforward analyses which simply smear array contents uniformly across the extent of the array. For given unit loadings in standard containers, practical expressions for neutron multiplication depend only on overall array shape, size and reflective boundary

Critical Power Response to Power Oscillations in Boiling Water Reactors

International Nuclear Information System (INIS)

Farawila, Yousef M.; Pruitt, Douglas W.

2003-01-01

The response of the critical power ratio to boiling water reactor (BWR) power oscillations is essential to the methods and practice of mitigating the effects of unstable density waves. Previous methods for calculating generic critical power response utilized direct time-domain simulations of unstable reactors. In this paper, advances in understanding the nature of the BWR oscillations and critical power phenomena are combined to develop a new method for calculating the critical power response. As the constraint of the reactor state - being at or slightly beyond the instability threshold - is removed, the new method allows the calculation of sensitivities to different operation and design parameters separately, and thus allows tighter safety margins to be used. The sensitivity to flow rate and the resulting oscillation frequency change are given special attention to evaluate the extension of the oscillation 'detect-and-suppress' methods to internal pump plants where the flow rate at natural circulation and oscillation frequency are much lower than jet pump plants

Sodium heat pipe module test for the SAFE-30 reactor prototype

International Nuclear Information System (INIS)

Reid, Robert S.; Sena, J. Tom; Martinez, Adam L.

2001-01-01

Reliable, long-life, low-cost heat pipes can enable safe, affordable space fission power and propulsion systems. Advanced versions of these systems can in turn allow rapid access to any point in the solar system. Twelve stainless steel-sodium heat pipe modules were built and tested at Los Alamos for use in a non-nuclear thermohydraulic simulation of the SAFE-30 reactor (Poston et al., 2000). SAFE-30 is a near-term, low-cost space fission system demonstration. The heat pipes were designed to remove thermal power from the SAFE-30 core, and transfer this power to an electrical power conversion system. These heat pipe modules were delivered to NASA Marshall Space Flight Center in August 2000 and were assembled and tested in a prototypical configuration during September and October 2000. The construction and test of one of the SAFE-30 modules is described

Sexual aggression when power is new: Effects of acute high power on chronically low-power individuals.

Science.gov (United States)

Williams, Melissa J; Gruenfeld, Deborah H; Guillory, Lucia E

2017-02-01

Previous theorists have characterized sexually aggressive behavior as an expression of power, yet evidence that power causes sexual aggression is mixed. We hypothesize that power can indeed create opportunities for sexual aggression-but that it is those who chronically experience low power who will choose to exploit such opportunities. Here, low-power men placed in a high-power role showed the most hostility in response to a denied opportunity with an attractive woman (Studies 1 and 2). Chronically low-power men and women given acute power were the most likely to say they would inappropriately pursue an unrequited workplace attraction (Studies 3 and 4). Finally, having power over an attractive woman increased harassment behavior among men with chronic low, but not high, power (Study 5). People who see themselves as chronically denied power appear to have a stronger desire to feel powerful and are more likely to use sexual aggression toward that end. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

New maintenance strategy of Tokyo Electric Power Company and Fukushima Dai-ichi Nuclear Power Plant for effective ageing management and safe long-term operation

International Nuclear Information System (INIS)

Inagaki, Takeyuki; Yamashita, Norimichi

2009-01-01

Fukushima Dai-ichi Nuclear Power Plant is the oldest among three nuclear power plants owned and operated by Tokyo Electric Power Company, which consists of six boiling water reactor units. The commercial operation of Unit 1 was commenced in 1971 (37 years old) and Unit 6 in 1978 (29 years old). Currently ageing degradations of systems, structures and components are managed through maintenance programs, component replacement/refurbishment programs and long-term maintenance plans. The long-term maintenance plans are established through ageing management component replacement/refurbishment programs reviews performed before the 30th year of operation and they are for safe and reliable operation after 30 years (long-term operation). However the past maintenance actions and past component replacement/refurbishment programs were not always proactive and past operational experience and maintenance practices suggest that effective/proactive ageing management programs be introduced in earlier stage of the plant operation. In this circumstance, Tokyo Electric Power Company and Fukushima Dai-ichi Nuclear Power Plant are setting up a new maintenance strategy that includes 1) improving the normal maintenance programs by using ageing degradation data, 2) effective use of information on internal/external operational experience and maintenance practices related to ageing, and 3) proactive component/equipment refurbishment programs during a refreshment outage for safe and reliable long-term operation. To accomplish the goal of this strategy, strengthening engineering capability of plant staff members is a crucial required for the plant. The objective of this paper is to briefly explain main results ageing management reviews, past and current significant ageing issues and management programs against them, and the new maintenance strategy established by Tokyo Electric Power Company and Fukushima Dai-ichi Nuclear Power Plant. (author)

What’s so Critical about Critical Neuroscience? -Rethinking Experiment, Enacting Critique

Directory of Open Access Journals (Sweden)

Des eFitzgerald

2014-05-01

Full Text Available In the midst of on-going hype about the power and potency of the new brain sciences, scholars within ‘Critical Neuroscience’ have called for a more nuanced and sceptical neuroscientific knowledge-practice. Drawing especially on the Frankfurt School, they urge neuroscientists towards a more critical approach – one that re-inscribes the objects and practices of neuroscientific knowledge within webs of social, cultural, historical and political-economic contingency. This paper is an attempt to open up the black-box of ‘critique’ within Critical Neuroscience itself. Specifically, we argue that limiting enactments of critique to the invocation of context misses the force of what a highly-stylized and tightly-bound neuroscientific experiment can actually do. We show that, within the neuroscientific experiment itself, the world-excluding and context-denying ‘rules of the game’ may also enact critique, in novel and surprising forms, while remaining formally independent of the workings of society, and culture, and history. To demonstrate this possibility, we analyze the Optimally Interacting Minds paradigm, a neuroscientific experiment that used classical psychophysical methods to show that, in some situations, people worked better as a collective, and not as individuals – a claim that works precisely against reactionary tendencies that prioritise individual over collective agency, but that was generated and legitimized entirely within the formal, context-denying conventions of neuroscientific experimentation. At the heart of this paper is a claim that it was precisely the rigours and rules of the experimental game that allowed these scientists to enact some surprisingly critical, and even radical, gestures. We conclude by suggesting that, in the midst of large-scale neuroscientific initiatives, it may be 'experiment,' and not 'context,' that forms the meeting-ground between neuro-biological and socio-political research practices.

Scenarios for low carbon and low water electric power plant ...

Science.gov (United States)

In the water-energy nexus, water use for the electric power sector is critical. Currently, the operational phase of electric power production dominates the electric sector's life cycle withdrawal and consumption of fresh water resources. Water use associated with the fuel cycle and power plant equipment manufacturing phase is substantially lower on a life cycle basis. An outstanding question is: how do regional shifts to lower carbon electric power mixes affect the relative contribution of the upstream life cycle water use? To test this, we examine a range of scenarios comparing a baseline with scenarios of carbon reduction and water use constraints using the MARKet ALlocation (MARKAL) energy systems model with ORD's 2014 U.S. 9-region database (EPAUS9r). The results suggest that moving toward a low carbon and low water electric power mix may increase the non-operational water use. In particular, power plant manufacturing water use for concentrating solar power, and fuel cycle water use for biomass feedstock, could see sharp increases under scenarios of high deployment of these low carbon options. Our analysis addresses the following questions. First, how does moving to a lower carbon electricity generation mix affect the overall regional electric power water use from a life cycle perspective? Second, how does constraining the operational water use for power plants affect the mix, if at all? Third, how does the life cycle water use differ among regions under

Relations between high and low power groups: the importance of legitimacy.

Science.gov (United States)

Hornsey, Matthew J; Spears, Russell; Cremers, Iris; Hogg, Michael A

2003-02-01

Using a social identity perspective, two experiments examined the effects of power and the legitimacy of power differentials on intergroup bias. In Experiment 1, 125 math-science students were led to believe that they had high or low representation in a university decision-making body relative to social-science students and that this power position was either legitimate or illegitimate. Power did not have an independent effect on bias; rather, members of both high and low power groups showed more bias when the power hierarchy was illegitimate than when it was legitimate. This effect was replicated in Experiment 2 (N = 105). In addition, Experiment 2 showed that groups located within an unfair power hierarchy expected the superordinate power body to be more discriminatory than did those who had legitimately high or low power. The results are discussed in terms of their implications for group relations. Copyright 2003 Society for Personality and Social Psychology, Inc.

Safe operation of research reactors and critical assemblies. Code of practice and annexes. 1984 ed

International Nuclear Information System (INIS)

1984-01-01

The safe operation of research reactors and critical assemblies (hereafter termed 'reactors') requires proper design, construction, management and supervision. This Code of Practice deals mainly with management and supervision. The provisions of the Code apply to the whole life of the reactor, including modification, updating and upgrading. The Code may be subject to revision in the light of experience and the state of technology. The Code is aimed at defining minimum requirements for the safe operation of reactors. Emphasis is placed on which safety requirements should be met rather than on specifying how these requirements may be met. The Code also provides guidance and information to persons and authorities responsible for the operation of reactors. The Code recommends that documents dealing with the operation of reactors and including safety analyses be prepared and submitted for review and approval to a regulatory body. Operation would be authorized on the understanding that it would comply with limits and conditions designed to ensure safety. The Code covers a wide range of reactor types, which gives rise to a variety of safety issues. Safety issues applicable to specific reactor types only (e.g. fast reactors) are not necessarily covered in this Code. Some of the recommendations in the Code are not directly applicable to critical assemblies. A recommendation may therefore be interpreted according to the type of reactor concerned. In such cases the words 'adequate' and 'appropriate' are used to mean 'adequate' or 'appropriate' for the type of reactor under consideration.

Critical experiments in support of the CNPS [Compact Nuclear Power Source] program

International Nuclear Information System (INIS)

Hansen, G.E.; Audas, J.H.; Martin, E.R.; Pederson, R.A.; Spriggs, G.D.; White, R.H.

1988-01-01

Zero-power static and kinetic measurements have been made on a mock-up of the Compact Nuclear Power Source (CNPS), a graphite moderated, graphite reflected, U(19.9% 235 U) fueled reactor design. Critical configurations were tracked from a first clean configuration (184 most central fuel channels filled and all control rod and heat pipe channels empty) to a fully loaded configuration (all 492 fuel channels filled, core-length stainless steel pipe in the twelve heat-pipe channels, and approximately half-core-length boron carbide in the outer 4 control rod channels. Reactor physics data such as material worths and neutron lifetime are presented only for the clean and fully loaded configurations

Intrinsically Safe Robot Arm : Adjustable Static Balancing and Low Power Actuation

NARCIS (Netherlands)

Vermeulen, M.; Wisse, M.

2010-01-01

We present a design for a manipulator that is intrinsically mechanically safe, i.e. it can not cause pain (let alone damage) to a human being even if the control system has a failure. Based on the pressure pain thresholds for human skin, we derive a pinching safety constraint that limits the

Evaluation of Saxton critical experiments

Energy Technology Data Exchange (ETDEWEB)

Joo, Hyung Kook; Noh, Jae Man; Jung, Hyung Guk; Kim, Young Il; Kim, Young Jin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1998-12-31

As a part of International Criticality Safety Benchmark Evaluation Project (ICSBEP), SAXTON critical experiments were reevaluated. The effects of k{sub eff} of the uncertainties in experiment parameters, fuel rod characterization, soluble boron, critical water level, core structure, {sup 241}Am and {sup 241}Pu isotope number densities, random pitch error, duplicated experiment, axial fuel position, model simplification, etc., were evaluated and added in benchmark-model k{sub eff}. In addition to detailed model, the simplified model for Saxton critical experiments was constructed by omitting the top, middle, and bottom grids and ignoring the fuel above water. 6 refs., 1 fig., 3 tabs. (Author)

Evaluation of Saxton critical experiments

Energy Technology Data Exchange (ETDEWEB)

Joo, Hyung Kook; Noh, Jae Man; Jung, Hyung Guk; Kim, Young Il; Kim, Young Jin [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-12-31

As a part of International Criticality Safety Benchmark Evaluation Project (ICSBEP), SAXTON critical experiments were reevaluated. The effects of k{sub eff} of the uncertainties in experiment parameters, fuel rod characterization, soluble boron, critical water level, core structure, {sup 241}Am and {sup 241}Pu isotope number densities, random pitch error, duplicated experiment, axial fuel position, model simplification, etc., were evaluated and added in benchmark-model k{sub eff}. In addition to detailed model, the simplified model for Saxton critical experiments was constructed by omitting the top, middle, and bottom grids and ignoring the fuel above water. 6 refs., 1 fig., 3 tabs. (Author)

The GT-MHR - clear, economic, and safe power for the Pacific Rim

International Nuclear Information System (INIS)

Blue, L.S.; Etzel, K.T.; Simon, W.A.; Wistrom, J.D.

1994-01-01

In recent decades the nations of the Pacific Rim have outpaced the rest of the world in economic growth. Beyond an abundant labor market and the region's natural resources, energy has played a pivotal role in fuelling this boom. The diverse sources of this energy largely reflect the naturally occurring fuel assets in the Rim countries. Only in the countries where these resources are less plentiful has nuclear energy become a significant sources of electric power generation. Persuasive as the argument for non-polluting power may be by itself it does not sell the nuclear energy option. In addition to being clean it must also be economically competitive and very safe. The authors claim that the Gas-Turbine Modular Helium Reactor (GT-MHR) is an advances nuclear power system that addresses the issues, and should be viewed as an attractive candidate to meet future energy needs. The GT-MHR derives from the coupling of a small, passively safe, modular reactor directly with a compact power conversion module. It uses the Brayton cycle to produce electricity directly with the primary helium coolant driving the turbine-generator. Thus, it shows promise for a quantum reduction in power generation costs by increasing plant efficiency to a remarkable 48% This paper highlights the advantages of the fact that the design is based on proven technology, and offers a clean, economic and safe energy for electricity and high temperature process heat. 2 refs., 4 figs

Integrated approach to economical, reliable, safe nuclear power production

International Nuclear Information System (INIS)

1982-06-01

An Integrated Approach to Economical, Reliable, Safe Nuclear Power Production is the latest evolution of a concept which originated with the Defense-in-Depth philosophy of the nuclear industry. As Defense-in-Depth provided a framework for viewing physical barriers and equipment redundancy, the Integrated Approach gives a framework for viewing nuclear power production in terms of functions and institutions. In the Integrated Approach, four plant Goals are defined (Normal Operation, Core and Plant Protection, Containment Integrity and Emergency Preparedness) with the attendant Functional and Institutional Classifications that support them. The Integrated Approach provides a systematic perspective that combines the economic objective of reliable power production with the safety objective of consistent, controlled plant operation

Analysis of Fresh Fuel Critical Experiments Appropriate for Burnup Credit Validation

International Nuclear Information System (INIS)

DeHart, M.D.

1995-01-01

The ANS/ANS-8.1 standard requires that calculational methods used in determining criticality safety limits for applications outside reactors be validated by comparison with appropriate critical experiments. This report provides a detailed description of 34 fresh fuel critical experiments and their analyses using the SCALE-4.2 code system and the 27-group ENDF/B-IV cross-section library. The 34 critical experiments were selected based on geometry, material, and neutron interaction characteristics that are applicable to a transportation cask loaded with pressurized-water-reactor spent fuel. These 34 experiments are a representative subset of a much larger data base of low-enriched uranium and mixed-oxide critical experiments. A statistical approach is described and used to obtain an estimate of the bias and uncertainty in the calculational methods and to predict a confidence limit for a calculated neutron multiplication factor. The SCALE-4.2 results for a superset of approximately 100 criticals are included in uncertainty analyses, but descriptions of the individual criticals are not included

Probabilistic safety assessments of nuclear power plants for low power and shutdown modes

International Nuclear Information System (INIS)

2000-03-01

Within the past several years the results of nuclear power plant operating experience and performance of probabilistic safety assessments (PSAs) for low power and shutdown operating modes have revealed that the risk from operating modes other than full power may contribute significantly to the overall risk from plant operations. These early results have led to an increased focus on safety during low power and shutdown operating modes and to an increased interest of many plant operators in performing shutdown and low power PSAs. This publication was developed to provide guidance and insights on the performance of PSA for shutdown and low power operating modes. The preparation of this publication was initiated in 1994. Two technical consultants meetings were conducted in 1994 and one in February 1999 in support of the development of this report

Evaluation of Accuracy of Calculational Prediction of Criticality Based on ICSBEP Handbook Experiments

International Nuclear Information System (INIS)

Golovko, Yury; Rozhikhin, Yevgeniy; Tsibulya, Anatoly; Koscheev, Vladimir

2008-01-01

Experiments with plutonium, low enriched uranium and uranium-233 from the ICSBEP Handbook are being considered in this paper. Among these experiments it was selected only those, which seem to be the most relevant to the evaluation of uncertainty of critical mass of mixtures of plutonium or low enriched uranium or uranium-233 with light water. All selected experiments were examined and covariance matrices of criticality uncertainties were developed along with some uncertainties were revised. Statistical analysis of these experiments was performed and some contradictions were discovered and eliminated. Evaluation of accuracy of prediction of criticality calculations was performed using the internally consistent set of experiments with plutonium, low enriched uranium and uranium-233 remained after the statistical analyses. The application objects for the evaluation of calculational prediction of criticality were water-reflected spherical systems of homogeneous aqueous mixtures of plutonium or low enriched uranium or uranium-233 of different concentrations which are simplified models of apparatus of external fuel cycle. It is shows that the procedure allows to considerably reduce uncertainty in k eff caused by the uncertainties in neutron cross-sections. Also it is shows that the results are practically independent of initial covariance matrices of nuclear data uncertainties. (authors)

Nuclear power plant operation experience - a feedback programme

International Nuclear Information System (INIS)

Banica, I.; Sociu, F.; Margaritescu, C.

1994-01-01

An effective high quality maintenance programme is required for the safe reliable operation of a nuclear power plant. To achieve the objectives of such a programme, both plant management and staff must be highly dedicated and motivated to perform high quality work at all levels. Operating and maintenance experience data collections and analysis are necessary in order to enhance the safety of the plant and reliability of the structures systems and components throughout their operating life. Significant events, but also minor incident, may reveal important deficiencies or negative trends adverse to safety. Therefore, a computer processing system for collecting, classifying and evaluating abnormal events or findings concerning operating-maintenance and for feeding back the results of the lessons learned from experience into the design and the operation of our nuclear power plant is considered to be of paramount importance. (Author)

Pressure ulcer incidence and progression in critically ill subjects: influence of low air loss mattress versus a powered air pressure redistribution mattress.

Science.gov (United States)

Black, Joyce; Berke, Christine; Urzendowski, Gail

2012-01-01

The primary objective of this study was to compare facility-acquired pressure ulcer incidence and progression of pressure ulcers present on admission in critically ill patients, using 2 different support surfaces. We completed a comparison cohort study in a surgical intensive care unit (ICU). The study setting was a 12-bed cardiovascular ICU in a university-based hospital in the Midwestern United States. The sample comprised 52 critically ill patients; 31 were placed on low air loss weight-based pressure redistribution-microclimate management system beds and 21 were placed on integrated powered air pressure redistribution beds. Prior to the start of the study, 5 low airloss beds were placed in open rooms in the cardiovascular surgical ICU. Inclusion criteria were anticipated ICU stay of 3 days, and patients did not receive a speciality bed for pulmonary or wound issues. Initial assessment of the patients included risk assessment and prior events that would increase risk for pressure ulcer development such as extended time in operating room, along with skin assessment for existing pressure ulcers. Subjects in both groups had ongoing skin assessment every 3 to 4 days and a subjective evaluation of heel elevation and turning or repositioning by the researcher. Data were collected until the subjects were dismissed from the ICU. Patients admitted to the unit were assigned to open rooms following the usual protocols. The mean length of stay was 7.0 days, with an 8.1-day length of stay for subjects on "low air loss with microclimate management" beds (LAL-MCM) and 6.6 days on the integrated power pressure air redistribution (IP-AR) beds (P = NS). The incidence of pressure ulcers on the buttocks, sacrum, or coccyx was 0% (0/31) on the low air loss bed and 18% (4/21) on the IP-AR bed (P = .046). Five subjects had 6 pressure ulcers on admission. Two pressure ulcers on 2 patients worsened on the integrated power air redistribution beds, which required specialty bed rental

Critical experiment program of heterogeneous core composed for LWR fuel rods and low enriched uranyl nitrate solution

International Nuclear Information System (INIS)

Miyoshi, Yoshinori; Yamamoto, Toshihiro; Watanabe, Shouichi; Nakamura, Takemi

2003-01-01

In order to stimulate the criticality characteristics of a dissolver in a reprocessing plant, a critical experiment program of heterogeneous cores is under going at a Static Critical Experimental Facility, STACY in Japan Atomic Energy Research Institute, JAERI. The experimental system is composed of 5w/o enriched PWR-type fuel rod array immersed in 6w/o enriched uranyl nitrate solution. First series of experiments are basic benchmark experiments on fundamental critical data in order to validate criticality calculation codes for 'general-form system' classified in the Japanese Criticality Safety Handbook, JCSHB. Second series of experiments are concerning the neutron absorber effects of fission products related to the burn-up credit Level-2. For demonstrating the reactivity effects of fission products, reactivity effects of natural elements such as Sm, Nd, Eu and 103 Rh, 133 Cs, solved in the nitrate solution are to be measured. The objective of third series of experiments is to validate the effect of gadolinium as a soluble neutron poison. Properties of temperature coefficients and kinetic parameters are also studied, since these parameters are important to evaluate the transient behavior of the criticality accident. (author)

Study of methodology for low power/shutdown fire PSA

International Nuclear Information System (INIS)

Yan Zhen; Li Zhaohua; Li Lin; Song Lei

2014-01-01

As a risk assessment technology based on probability, the fire PSA is accepted abroad by nuclear industry in its application in the risk assessment for nuclear power plants. Based on the industry experience, the fire-induced impact on the plant safety during low power and shutdown operation cannot be neglected, therefore fire PSA can be used to assess the corresponding fire risk. However, there is no corresponding domestic guidance/standard as well as accepted analysis methodology up to date. Through investigating the latest evolvement on fire PSA during low power and shutdown operation, and integrating its characteristic with the corresponding engineering experience, an engineering methodology to evaluate the fire risk during low power and shutdown operation for nuclear power plant is established in this paper. In addition, an analysis demonstration as an example is given. (authors)

The human factor: the critical importance of effective teamwork and communication in providing safe care.

Science.gov (United States)

Leonard, M; Graham, S; Bonacum, D

2004-10-01

Effective communication and teamwork is essential for the delivery of high quality, safe patient care. Communication failures are an extremely common cause of inadvertent patient harm. The complexity of medical care, coupled with the inherent limitations of human performance, make it critically important that clinicians have standardised communication tools, create an environment in which individuals can speak up and express concerns, and share common "critical language" to alert team members to unsafe situations. All too frequently, effective communication is situation or personality dependent. Other high reliability domains, such as commercial aviation, have shown that the adoption of standardised tools and behaviours is a very effective strategy in enhancing teamwork and reducing risk. We describe our ongoing patient safety implementation using this approach within Kaiser Permanente, a non-profit American healthcare system providing care for 8.3 million patients. We describe specific clinical experience in the application of surgical briefings, properties of high reliability perinatal care, the value of critical event training and simulation, and benefits of a standardised communication process in the care of patients transferred from hospitals to skilled nursing facilities. Additionally, lessons learned as to effective techniques in achieving cultural change, evidence of improving the quality of the work environment, practice transfer strategies, critical success factors, and the evolving methods of demonstrating the benefit of such work are described.

An optimized low-power voltage controlled oscillator

Science.gov (United States)

Shah, Kriyang; Le, Hai Phuong; Singh, Jugdutt

2007-01-01

This paper presents an optimised low-power low-phase-noise Voltage Controlled Oscillator (VCO) for Bluetooth wireless applications. The system level design issues and tradeoffs related to Direct Conversion Receiver (DCR) and Low Intermediate Frequency (IF) architecture for Bluetooth are discussed. Subsequently, for a low IF architecture, the critical VCO performance parameters are derived from system specifications. The VCO presented in the paper is optimised by implementing a novel biasing circuit that employs two current mirrors, one at the top and the other one at the bottom of the cross-coupled complementary VCO, to give the exact replica of the current in both the arms of current mirror circuit. This approach, therefore, significantly reduces the system power consumption as well as improves the system performance. Results show that, the VCO consumes only 281μW of power at 2V supply. Its phase noise performance are -115dBc/Hz, -130dBc/Hz and -141dBc/Hz at the offset frequency of 1MHz, 3MHz and 5MHz respectively. Results indicate that 31% reduction in power consumption is achieved as compared to the traditional VCO design. These characteristics make the designed VCO a better candidate for Bluetooth wireless application where power consumption is the major issue.

Critical Heat Flux Phenomena at HighPressure & Low Mass Fluxes: NEUP Final Report Part I: Experiments

Energy Technology Data Exchange (ETDEWEB)

Corradini, Michael [Univ. of Wisconsin, Madison, WI (United States); Wu, Qiao [Oregon State Univ., Corvallis, OR (United States)

2015-04-30

This report is a preliminary document presenting an overview of the Critical Heat Flux (CHF) phenomenon, the High Pressure Critical Heat Flux facility (HPCHF), preliminary CHF data acquired, and the future direction of the research. The HPCHF facility has been designed and built to study CHF at high pressure and low mass flux ranges in a rod bundle prototypical of conceptual Small Modular Reactor (SMR) designs. The rod bundle is comprised of four electrically heated rods in a 2x2 square rod bundle with a prototypic chopped-cosine axial power profile and equipped with thermocouples at various axial and circumferential positions embedded in each rod for CHF detection. Experimental test parameters for CHF detection range from pressures of ~80 – 160 bar, mass fluxes of ~400 – 1500 kg/m2s, and inlet water subcooling from ~30 – 70°C. The preliminary data base established will be further extended in the future along with comparisons to existing CHF correlations, models, etc. whose application ranges may be applicable to the conditions of SMRs.

First start-up of nuclear criticality safety experiment facility for uranyl nitrate solution

International Nuclear Information System (INIS)

Zhu Qingfu; Shi Yongqian; Shen Leisheng; Hu Dingsheng; Zhao Shouzhi; He Tao; Sun Zheng; Lin Shenghuo; Yao Shigui

2005-01-01

The uranyl nitrate solution experiment facility for the research on nuclear criticality safety is described. The nuclear fuel loading steps in the first start-up for water-reflected core are presented. During the experiments, the critical volume of uranyl nitrate solution was determined as 20479.62 mL with count rate inverse extrapolation method, reactivity interpolation method, and steady power method. By calculation, critical mass of 235 U was derived as 1579.184 g from experimental data. The worth of control rods was also calibrated in the first start-up of the facility. (authors)

Subcriticality calculations for the FFTF reverse approach to critical experiment

International Nuclear Information System (INIS)

Selby, D.L.; Flanagan, G.F.

1975-01-01

The reverse approach to critical (RAC) experiments were performed in the ZPR-IX critical facility at Argonne National Laboratory. One of the major objectives of this project is to determine the adequacy of the low-level flux monitor (LLFM) detectors for initial loading of the Fast Flux Test Facility (FFTF). 5 references

Assessment of nuclear reactor concepts for low power space applications

Science.gov (United States)

Klein, Andrew C.; Gedeon, Stephen R.; Morey, Dennis C.

1988-01-01

The results of a preliminary small reactor concepts feasibility and safety evaluation designed to provide a first order validation of the nuclear feasibility and safety of six small reactor concepts are given. These small reactor concepts have potential space applications for missions in the 1 to 20 kWe power output range. It was concluded that low power concepts are available from the U.S. nuclear industry that have the potential for meeting both the operational and launch safety space mission requirements. However, each design has its uncertainties, and further work is required. The reactor concepts must be mated to a power conversion technology that can offer safe and reliable operation.

The degradation diagnosis of low voltage cables used at nuclear power plants

International Nuclear Information System (INIS)

Yamamoto, Toshio; Ashida, Tetsuya; Ikeda, Takeshi; Yasuhara, Takeshi; Takechi, Kei; Araki, Shogo

2001-01-01

Low voltage cables which have been used for the supply of electric power and the propagation of control signals in nuclear power plants must be sound for safe and stable operation. The long use of nuclear power plants has been reviewed, and the degradation diagnosis to estimate the soundness of low voltage cables has been emphasized. Mitsubishi Cable Industries has established a degradation diagnosis method of cables which convert the velocity of ultrasonic wave in the surface layer of the cable insulation or jacket into breaking elongation, and has developed a degradation diagnosis equipment of low voltage cables used at nuclear power plants in cooperation with Mitsubishi Heavy Industries. This equipment can be moved by an ultrasonic probe by sequential control and measure the ultrasonic velocity automatically. It is capable of a fast an sensitive diagnosis of the cables. We report the outline of this degradation diagnosis equipment and an example of the adaptability estimation at an actual nuclear power plant. (author)

Integral Battery Power Limiting Circuit for Intrinsically Safe Applications

Science.gov (United States)

Burns, Bradley M.; Blalock, Norman N.

2010-01-01

A circuit topology has been designed to guarantee the output of intrinsically safe power for the operation of electrical devices in a hazardous environment. This design uses a MOSFET (metal oxide semiconductor field-effect transistor) as a switch to connect and disconnect power to a load. A test current is provided through a separate path to the load for monitoring by a comparator against a preset threshold level. The circuit is configured so that the test current will detect a fault in the load and open the switch before the main current can respond. The main current passes through the switch and then an inductor. When a fault occurs in the load, the current through the inductor cannot change immediately, but the voltage drops immediately to safe levels. The comparator detects this drop and opens the switch before the current in the inductor has a chance to respond. This circuit protects both the current and voltage from exceeding safe levels. Typically, this type of protection is accomplished by a fuse or a circuit breaker, but in order for a fuse or a circuit breaker to blow or trip, the current must exceed the safe levels momentarily, which may be just enough time to ignite anything in a hazardous environment. To prevent this from happening, a fuse is typically current-limited by the addition of the resistor to keep the current within safe levels while the fuse reacts. The use of a resistor is acceptable for non-battery applications where the wasted energy and voltage drop across the resistor can be tolerated. The use of the switch and inductor minimizes the wasted energy. For example, a circuit runs from a 3.6-V battery that must be current-limited to 200 mA. If the circuit normally draws 10 mA, then an 18-ohm resistor would drop 180 mV during normal operation, while a typical switch (0.02 ohm) and inductor (0.97 ohm) would only drop 9.9 mV. From a power standpoint, the current-limiting resistor protection circuit wastes about 18 times more power than the

Safe nuclear power for the Third World

International Nuclear Information System (INIS)

Johnson, W.R.; Lyon, C.F.; Redick, J.R.

1989-01-01

It is clear that using nuclear power for the generation of electricity is one way of reducing the emissions of CO 2 and other gases that contribute to the greenhouse effect. Equally clear is the fact that the reduction can be magnified by converting domestic, commercial, and industrial power-consuming activities from the direct use of fossil fuel sources to electrical energy. A major area for future progress in limiting CO 2 emissions is in the Third World, where population growth and expectations for a higher social and economic standard of living portend vast increases in future energy use. A number of problems come to mind as one contemplates the widespread expansion of nuclear energy use into the Third World. The authors propose a method involving the marriage of two currently evolving concepts by which nuclear electrical generation can be expanded throughout the world in a manner that will address these problems. The idea is to form multinational independent electric generating companies, or nuclear electric companies (NECs), that would design, build, operate, and service a standardized fleet of nuclear power plants. The plants would be of the Integral Fast Reactor (IFR) design, now under development at Argonne National Laboratory, and, in particular, a commercial conceptualization of the IFR sponsored by General Electric Company, the Power Reactor Inherently Safe Module (PRISM)

Theoretical, experimental and numerical diagnose of critical power point of thermoelectric generators

DEFF Research Database (Denmark)

Chen, Min; Gao, Xin

2014-01-01

of the critical power point in the series and parallel TEM arrays. Secondly, experiments of a series-parallel hybrid interconnected TEG are presented to clearly quantify the theoretical analyses. Finally, the hierarchical simulation, based on the SPICE (simulation program with integrated circuit emphasis...

Professionals Cultivations: critical to the safe operation & sustainable development of nuclear power

International Nuclear Information System (INIS)

Zheng, Mingguang

2017-01-01

Challenges to nuclear power development: Challenges to nuclear power: •Public acceptance & confidences shaking after SAs •Ecology concerning seriously on rad-waste & spent fuel •Both AP1000 & EPR delayed with investment greatly increased •Economic competition from Renewable & marginal effects from severe regulatory guides; Challenges from HR: •No peoples willing to enter industry for countries with NP phased out •No motivations to develop or innovate the new technology for countries with NP operation but no further planning •Professionals need badly for developing countries looking for more nuclear power •HR setup the balance between money & missions, prides & success

Validation of KENO V.a: Comparison with critical experiments

International Nuclear Information System (INIS)

Jordan, W.C.; Landers, N.F.; Petrie, L.M.

1986-12-01

Section 1 of this report documents the validation of KENO V.a against 258 critical experiments. Experiments considered were primarily high or low enriched uranium systems. The results indicate that the KENO V.a Monte Carlo Criticality Program accurately calculates a broad range of critical experiments. A substantial number of the calculations showed a positive or negative bias in excess of 1 1/2% in k-effective (k/sub eff/). Classes of criticals which show a bias include 3% enriched green blocks, highly enriched uranyl fluoride slab arrays, and highly enriched uranyl nitrate arrays. If these biases are properly taken into account, the KENO V.a code can be used with confidence for the design and criticality safety analysis of uranium-containing systems. Sections 2 of this report documents the results of investigation into the cause of the bias observed in Sect. 1. The results of this study indicate that the bias seen in Sect. 1 is caused by code bias, cross-section bias, reporting bias, and modeling bias. There is evidence that many of the experiments used in this validation and in previous validations are not adequately documented. The uncertainty in the experimental parameters overshadows bias caused by the code and cross sections and prohibits code validation to better than about 1% in k/sub eff/. 48 refs., 19 figs., 19 tabs

The human factor: the critical importance of effective teamwork and communication in providing safe care

OpenAIRE

Leonard, M; Graham, S; Bonacum, D

2004-01-01

Effective communication and teamwork is essential for the delivery of high quality, safe patient care. Communication failures are an extremely common cause of inadvertent patient harm. The complexity of medical care, coupled with the inherent limitations of human performance, make it critically important that clinicians have standardised communication tools, create an environment in which individuals can speak up and express concerns, and share common "critical language" to alert team members...

Westinghouse power distribution monitoring experience at Duke Power's McGuire Unit 1

International Nuclear Information System (INIS)

Grobmyer, L.R.; Cash, M.T.; Kitlan, M.S.; Impink, A.J. Jr.

1987-01-01

In the evolution of the Westinghouse methodology of assuring safe core power distributions, emphasis was placed on analysis and not on continuous detailed core monitoring. Power distribution monitoring is currently achieved by periodic surveillances using the movable in-core detector system (MIDS) and by continuous observations of the two-section excore power range detectors. Control of the power distribution is regulated by limits on the indications from these systems, by limits on control rod insertion, and by operational constraints on the position indication systems. As more plants come on line and as more utilities take over the fuel design function for themselves, the desire for better core monitoring becomes evident. Also, the need and desire by the utilities to have more control over their operating margin has motivated the industry to offer and/or upgrade core monitoring systems. Westinghouse and Duke Power are participants in a joint development program to finalize the development of the core on-line surveillance monitoring and operations system (COSMOS). This final stage of development consists of prototype field trials at the McGuire Nuclear Plant. The purpose of the prototype program is to determine how well the design objectives are met and how to improve the system based on the operating experience at McGuire. Another purpose of this prototype program is to generate the necessary experience and information to develop a topical report for the US Nuclear Regulatory Commission to obtain a licensing basis for technical specification relaxation

Completion of the first approach to critical for the seven percent critical experiment

International Nuclear Information System (INIS)

Barber, A. D.; Harms, G. A.

2009-01-01

The first approach-to-critical experiment in the Seven Percent Critical Experiment series was recently completed at Sandia. This experiment is part of the Seven Percent Critical Experiment which will provide new critical and reactor physics benchmarks for fuel enrichments greater than five weight percent. The inverse multiplication method was used to determine the state of the system during the course of the experiment. Using the inverse multiplication method, it was determined that the critical experiment went slightly supercritical with 1148 fuel elements in the fuel array. The experiment is described and the results of the experiment are presented. (authors)

Power affects performance when the pressure is on: evidence for low-power threat and high-power lift.

Science.gov (United States)

Kang, Sonia K; Galinsky, Adam D; Kray, Laura J; Shirako, Aiwa

2015-05-01

The current research examines how power affects performance in pressure-filled contexts. We present low-power-threat and high-power-lift effects, whereby performance in high-stakes situations suffers or is enhanced depending on one's power; that is, the power inherent to a situational role can produce effects similar to stereotype threat and lift. Three negotiations experiments demonstrate that role-based power affects outcomes but only when the negotiation is diagnostic of ability and, therefore, pressure-filled. We link these outcomes conceptually to threat and lift effects by showing that (a) role power affects performance more strongly when the negotiation is diagnostic of ability and (b) underperformance disappears when the low-power negotiator has an opportunity to self-affirm. These results suggest that stereotype threat and lift effects may represent a more general phenomenon: When the stakes are raised high, relative power can act as either a toxic brew (stereotype/low-power threat) or a beneficial elixir (stereotype/high-power lift) for performance. © 2015 by the Society for Personality and Social Psychology, Inc.

Impact of Powered Knee-Ankle Prosthesis on Low Back Muscle Mechanics in Transfemoral Amputees: A Case Series

Directory of Open Access Journals (Sweden)

Chandrasekaran Jayaraman

2018-03-01

Full Text Available Regular use of prostheses is critical for individuals with lower limb amputations to achieve everyday mobility, maintain physical and physiological health, and achieve a better quality of life. Use of prostheses is influenced by numerous factors, with prosthetic design playing a critical role in facilitating mobility for an amputee. Thus, prostheses design can either promote biomechanically efficient or inefficient gait behavior. In addition to increased energy expenditure, inefficient gait behavior can expose prosthetic user to an increased risk of secondary musculoskeletal injuries and may eventually lead to rejection of the prosthesis. Consequently, researchers have utilized the technological advancements in various fields to improve prosthetic devices and customize them for user specific needs. One evolving technology is powered prosthetic components. Presently, an active area in lower limb prosthetic research is the design of novel controllers and components in order to enable the users of such powered devices to be able to reproduce gait biomechanics that are similar in behavior to a healthy limb. In this case series, we studied the impact of using a powered knee-ankle prostheses (PKA on two transfemoral amputees who currently use advanced microprocessor controlled knee prostheses (MPK. We utilized outcomes pertaining to kinematics, kinetics, metabolics, and functional activities of daily living to compare the efficacy between the MPK and PKA devices. Our results suggests that the PKA allows the participants to walk with gait kinematics similar to normal gait patterns observed in a healthy limb. Additionally, it was observed that use of the PKA reduced the level of asymmetry in terms of mechanical loading and muscle activation, specifically in the low back spinae regions and lower extremity muscles. Further, the PKA allowed the participants to achieve a greater range of cadence than their predicate MPK, thus allowing them to safely

Nuclear criticality experiments from 1943 to 1978: an annotated bibliography. Volume 1. Main listing

Energy Technology Data Exchange (ETDEWEB)

Koponen, B.L.; Wilcox, T.P.; Hampel, V.E.

1979-04-24

The bibliography contains 1067 citations from the literature of critical and near-critical nuclear experiments. It provides an up-to-date index to reports containing useful data for many types of criticality studies. Most of the reports can provide specifications for relatively simple critical configurations necessary for validating nuclear constants and calculational techniques. The reports of more than 1143 experimentors at 38 international facilities since 1943 are cross-referenced. The collection contains the prototypes of many different designs of nuclear reactors and studies performed to insure the safe use of fissile materials in chemical processing plants, storage facilities, and transportation containers. The bibliography has three volumes. Volume 1 contains the main listing of citations with abstracts. Volume 2 is a set of indexes organized by report number, publication date, experimental facility, and author name. Volume 3 provides a subject index, concorded on the significant keyphrases derived from titles, and an index of keyterms derived from titles, and an index of keyterms extracted from titles and abstracts. The bibliography was printed by computer as a selection from a computerized system at Lawrence Livermore Laboratory contaning information and data on criticality experiments.

Nuclear criticality experiments from 1943 to 1978. An annotated bibliography: Volume 1, main listing

International Nuclear Information System (INIS)

Koponen, B.L.; Wilcox, T.P.; Hampel, V.E.

1979-05-01

This report only describes the bibliography which contains 1067 citations from the literature of critical and near-critical nuclear experiments. The bibliography provides an up-to-date index to reports containing useful data for many types of criticality studies. Most of the reports can provide specifications for relatively simple critical configurations necessary for validating nuclear constants and calculational techniques. The reports of more than 1143 experimentors at 38 international facilities since 1943 are cross-referenced. This collection contains the prototypes of many different designs of nuclear reactors and studies performed to ensure the safe use of fissile materials in chemical processing plants, storage facilities, and transportation containers. The bibliography has three volumes. Volume 1 contains the main listing of citations with abstracts. Volume 2 is a set of indexes organized by report number, publication date, experimental facility, and author name. Volume 3 provides a subject index, concorded on the significant keyphrases derived from titles, and an index of key terms extracted from titles and abstracts. The bibliography was printed by computer as a selection from a computerized system at Lawrence Livermore Laboratory containing information and data on criticality experiments

Low-Power Differential SRAM design for SOC Based on the 25-um Technology

Science.gov (United States)

Godugunuri, Sivaprasad; Dara, Naveen; Sambasiva Nayak, R.; Nayeemuddin, Md; Singh, Yadu, Dr.; Veda, R. N. S. Sunil

2017-08-01

In recent, the SOC styles area unit the vast complicated styles in VLSI these SOC styles having important low-power operations problems, to comprehend this we tend to enforced low-power SRAM. However these SRAM Architectures critically affects the entire power of SOC and competitive space. To beat the higher than disadvantages, during this paper, a low-power differential SRAM design is planned. The differential SRAM design stores multiple bits within the same cell, operates at minimum in operation low-tension and space per bit. The differential SRAM design designed supported the 25-um technology using Tanner-EDA Tool.

Preliminary experience and near future utilization programmes of the MPR-30 fueled by LEU [low enriched uranium

International Nuclear Information System (INIS)

Arbie, B.; Soentono, S.

1987-01-01

The MTR type reactor MPR-30 G.A. Siwabessy, located at PUSPIPTEK Serpong has recently reached its first criticality. This multipurpose reactor is supposed to be the first MTR type reactor in the world that is designed and constructed to be fueled by low enriched uranium. Preliminary experience covering the approach to the first criticality and the excess reactivity loading as well as some thermal hydraulics and power ascension tests are briefly presented and discussed. The near future utilization programmes during and after commissioning are also presented. (Author)

Method for making a low density polyethylene waste form for safe disposal of low level radioactive material

Science.gov (United States)

Colombo, P.; Kalb, P.D.

1984-06-05

In the method of the invention low density polyethylene pellets are mixed in a predetermined ratio with radioactive particulate material, then the mixture is fed through a screw-type extruder that melts the low density polyethylene under a predetermined pressure and temperature to form a homogeneous matrix that is extruded and separated into solid monolithic waste forms. The solid waste forms are adapted to be safely handled, stored for a short time, and safely disposed of in approved depositories.

Shutdown and low-power operation at commercial nuclear power plants in the United States

International Nuclear Information System (INIS)

1993-09-01

The report contains the results of the NRC Staff's evaluation of shutdown and low-power operations at US commercial nuclear power plants. The report describes studies conducted by the staff in the following areas: Operating experience related to shutdown and low-power operations, probabilistic risk assessment of shutdown and low-power conditions and utility programs for planning and conducting activities during periods the plant is shut down. The report also documents evaluations of a number of technical issues regarding shutdown and low-power operations performed by the staff, including the principal findings and conclusions. Potential new regulatory requirements are discussed, as well as potential changes in NRC programs. A draft report was issued for comment in February 1992. This report is the final version and includes the responses to the comments along with the staff regulatory analysis of potential new requirements

Power-Cooling-Mismatch Test Series Test PCM-7. Experiment operating specifications

International Nuclear Information System (INIS)

Sparks, D.T.; Smith, R.H.; Stanley, C.J.

1979-02-01

The experiment operating specifications for the Power-Cooling-Mismatch (PCM) Test PCM-7 to be conducted in the Power Burst Facility are described. The PCM Test Series was designed on the basis of a parametric evaluation of fuel behavior response with cladding temperature, rod internal pressure, time in film boiling, and test rod power being the variable parameters. The test matrix, defined in the PCM Experiment Requirements Document (ERD), encompasses a wide range of situations extending from pre-CHF (critical heat flux) PCMs to long duration operation in stable film boiling leading to rod failure

Identification of the low-energy excitations in a quantum critical system

Directory of Open Access Journals (Sweden)

Tom Heitmann

2017-05-01

Full Text Available We have identified low-energy magnetic excitations in a doped quantum critical system by means of polarized neutron scattering experiments. The presence of these excitations could explain why Ce(Fe0.76Ru0.242Ge2 displays dynamical scaling in the absence of local critical behavior or long-range spin-density wave criticality. The low-energy excitations are associated with the reorientations of the superspins of fully ordered, isolated magnetic clusters that form spontaneously upon lowering the temperature. The system houses both frozen clusters and dynamic clusters, as predicted by Hoyos and Vojta [Phys. Rev. B 74, 140401(R (2006].

The low power miniature neutron source reactors: Design, safety and applications

International Nuclear Information System (INIS)

Ahmed, Y.A.; Ewa, I.O.B.; Umar, M.; Bezboruah, T.; Johri, M.; Akaho, E.H.K.

2006-04-01

The Chinese Miniature Neutron Source Reactor (MNSR) is a low power research reactor with maximum thermal neutron flux of 1 x 10 12 n.cm -2 .s -1 in one of its inner irradiation channels and thermal power of approximately 30kW. The MNSR is designed based on the Canadian SLOWPOKE reactor and is one of the smallest commercial research reactors presently available in the world. Its commercial versions currently in operation in China, Ghana, Iran, Nigeria, Pakistan and Syria, is considered as an excellent tool for Neutron Activation Analysis (NAA), training of Scientist, and Engineers in nuclear science and technology and small scale radioisotope production. The paper highlights the basic design and theory of the commercial MNSR, its safety features, applications and advantages over the Chinese Prototype. The experimental flux characteristics determined in this work and in similar studies by other authors reveal that the commercial MNSR has more flux stability, longer life span, higher negative temperature coefficient of reactivity and low under-moderation compared to its prototype in China. The result shows that the facility is safe for reactor physics experiments, teaching and training of students and also ideal for application of NAA for the determination of elemental composition of biological and environmental samples. It can also be a useful tool for geochemical and soil fertility mapping. (author)

The experiences to improve plant performance and reliability of Ko-Ri nuclear power plants

International Nuclear Information System (INIS)

Kang, Ho Weon

1998-01-01

This paper provides a discussion of the lessons learned from operational experience and the future plans to improve performance of the Ko-Ri plant. To operate nuclear power plants safely with good performance is the only way to mitigate the negative image of nuclear power generation to the public and to enhance the economical benefit compared to other electrical generation method. Therefore, in a continuous effort to overcome a negative challenge from outside, we have driven an aggressive 'OCTF' campaign as part of safety. As a result of our efforts, the following remarkable achievements have been accomplished. (1) 3 times of OCTF during recent three years (2) Selected twice as a top notch power plant on the list of NEI magazine in terms of plant capacity factor (3) No scram recorded in 1997 for all 4 units at Ko-Ri site. Ko-Ri is now undergoing the large scale plant betterment projects for retaking-off our operating performance to the level of new challenge target. Such improvement of critical components in the reactor coolant system and turbine system greatly contribute to increase the safety and reliability of the plant and to shortening of the planned outage period as well as to reduction of radiation exposure and radwaste. (Cho, G. S.). 5 tabs., 10 figs

Consideration of critical heat flux margin prediction by subcooled or low quality critical heat flux correlations

International Nuclear Information System (INIS)

Hejzlar, P.; Todreas, N.E.

1996-01-01

The accurate prediction of the critical heat flux (CHF) margin which is a key design parameter in a variety of cooling and heating systems is of high importance. These margins are, for the low quality region, typically expressed in terms of critical heat flux ratios using the direct substitution method. Using a simple example of a heated tube, it is shown that CHF correlations of a certain type often used to predict CHF margins, expressed in this manner, may yield different results, strongly dependent on the correlation in use. It is argued that the application of the heat balance method to such correlations, which leads to expressing the CHF margins in terms of the critical power ratio, may be more appropriate. (orig.)

Critical experiment study on uranyl nitrate solution experiment facility

International Nuclear Information System (INIS)

Zhu Qingfu; Shi Yongqian; Wang Jinrong

2005-01-01

The Uranyl Nitrate Solution Experiment Facility was constructed for the research on nuclear criticality safety. In this paper, the configuration of the facility is introduced; a series of critical experiments on uranyl nitrate solution is described later, which were performed for various uranium concentrations under different conditions, i.e. with or without neutron absorbers in the core and with or without water-reflector outside the core. Critical volume and the minimum 235U critical mass for different uranium concentrations are presented. Finally, theoretical analysis is made on the experimental results. (authors)

Safety training and safe operating procedures written for PBFA (Particle Beam Fusion Accelerator) II and applicable to other pulsed power facilities

Energy Technology Data Exchange (ETDEWEB)

Donovan, G.L.; Goldstein, S.A.

1986-12-01

To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards.

Safety training and safe operating procedures written for PBFA [Particle Beam Fusion Accelerator] II and applicable to other pulsed power facilities

International Nuclear Information System (INIS)

Donovan, G.L.; Goldstein, S.A.

1986-12-01

To ensure that work in advancing pulsed power technology is performed with an acceptably low risk, pulsed power research facilities at Sandia National Laboratories must satisfy general safety guidelines established by the Department of Energy, policies and formats of the Environment, Safety, and Health (ES and H) Department, and detailed procedures formulated by the Pulsed Power Sciences Directorate. The approach to safety training and to writing safe operating procedures, and the procedures presented here are specific to the Particle Beam Fusion Accelerator II (PBFA II) Facility but are applicable as guidelines to other research and development facilities which have similar hazards

When Power Shapes Interpersonal Behavior: Low Relationship Power Predicts Men’s Aggressive Responses to Low Situational Power

Science.gov (United States)

Overall, Nickola C.; Hammond, Matthew D.; McNulty, James K.; Finkel, Eli J.

2016-01-01

When does power in intimate relationships shape important interpersonal behaviors, such as psychological aggression? Five studies tested whether possessing low relationship power was associated with aggressive responses, but (1) only within power-relevant relationship interactions when situational power was low, and (2) only by men because masculinity (but not femininity) involves the possession and demonstration of power. In Studies 1 and 2, men lower in relationship power exhibited greater aggressive communication during couples’ observed conflict discussions, but only when they experienced low situational power because they were unable to influence their partner. In Study 3, men lower in relationship power reported greater daily aggressive responses toward their partner, but only on days when they experienced low situational power because they were either (a) unable to influence their partner or (b) dependent on their partner for support. In Study 4, men who possessed lower relationship power exhibited greater aggressive responses during couples’ support-relevant discussions, but only when they had low situational power because they needed high levels of support. Study 5 provided evidence for the theoretical mechanism underlying men’s aggressive responses to low relationship power. Men who possessed lower relationship power felt less manly on days they faced low situational power because their partner was unwilling to change to resolve relationship problems, which in turn predicted greater aggressive responses to their partner. These results demonstrate that fully understanding when and why power is associated with interpersonal behavior requires differentiating between relationship and situational power. PMID:27442766

Health physics practices and experience at Duke Power Company

International Nuclear Information System (INIS)

Lewis, L.

1986-01-01

The history and development of the health physics and as-low-as-reasonably-achievable (ALARA) program at Duke Power Company's Oconee Nuclear Station is described as are the fundamental elements of the program and how the program works. The benefits of this health physics/ALARA program have been determined to be (a) improved quality of manpower planning and scheduling, (b) increased efficiency of shutdown activities, (c) reduced cost of shutdown, (d) immediate awareness of adverse job exposure trends, (e) better management information on exposure-related problems, (f) improved accuracy of personnel and job dose records, and (g) in general, improved outage performance and subsequent plant operation. Experience with the health physics/ALARA program is discussed in terms of (a) savings of critical path time, (b) maintaining ALARA personnel doses, and (c) record capacity factors

Study on the identification of main drivers affecting the performance of human operators during low power and shutdown operation

International Nuclear Information System (INIS)

Kim, Ar Ryum; Park, Jinkyun; Kim, Ji Tae; Kim, Jaewhan; Seong, Poong Hyun

2016-01-01

Highlights: • The performance of human operator during LPSD operation is significantly important. • Human performance is affected by drivers such as procedure, training, and etc. • Main drivers during LPSD operation at domestic NPPs were suggested. • It is expected that it will be used for estimating human reliability during LPSD operation. - Abstract: In the past, many researchers believed that a reactor during low power and shutdown operation was sufficiently safe. This belief has been changed by the number of accidents during such types of operation, which is significantly high. Also, it was pointed out that one of the main differences between low power and shutdown operation and full power operation is the significance of human action because there are huge amounts of human actions due to extensive maintenance and testing while automatic control and safety functions may be disabled and procedures are insufficient or incomplete. This paper suggests the main drivers in performing human reliability analysis. For this study, we reviewed eight reports relating to human performance during low power and shutdown operation and applied a root cause analysis method for 53 human or human-related events at domestic nuclear power plants to derive the main drivers that affect the occurrence of those events. As a result, several main drivers were derived, such as procedures, training, experience of personnel, and workload/stress. It is expected that these main drivers will be used to perform human reliability analysis for low power and shutdown operation.

On-state voltage drop based power limit detection of IGBT inverters

DEFF Research Database (Denmark)

Trintis, Ionut; Ghimire, Pramod; Munk-Nielsen, Stig

2015-01-01

Power density is a key performance factor in order to reduce the cost and size of a power converter. Because of the unknown junction temperature, today’s design margins are relatively high to ensure safe and a reliable operation. In this paper, the on-state voltage drop is measured online for all...... insulated gate bipolar transistors (IGBTs) in the inverter, using advanced gate driver. The die temperature is estimated and monitored on each device during power converter operation. Based on the monitored temperature in real time, the maximum power capability is detected. The output power is increased...... until a safe operating temperature of power modules. This enable a power density is increased by 11.16 kW/litre to 19.13 kW/litre in a low voltage power stack which is typically used in wind power converters. Experiment results are shown for safe operation of converter at around 1.2 MW, which is built...

Battery-Powered RF Pre-Ionization System for the Caltech Magnetohydrodynamically-Driven Jet Experiment: RF Discharge Properties and MHD-Driven Jet Dynamics

Science.gov (United States)

Chaplin, Vernon H.

This thesis describes investigations of two classes of laboratory plasmas with rather different properties: partially ionized low pressure radiofrequency (RF) discharges, and fully ionized high density magnetohydrodynamically (MHD)-driven jets. An RF pre-ionization system was developed to enable neutral gas breakdown at lower pressures and create hotter, faster jets in the Caltech MHD-Driven Jet Experiment. The RF plasma source used a custom pulsed 3 kW 13.56 MHz RF power amplifier that was powered by AA batteries, allowing it to safely float at 4-6 kV with the cathode of the jet experiment. The argon RF discharge equilibrium and transport properties were analyzed, and novel jet dynamics were observed. Although the RF plasma source was conceived as a wave-heated helicon source, scaling measurements and numerical modeling showed that inductive coupling was the dominant energy input mechanism. A one-dimensional time-dependent fluid model was developed to quantitatively explain the expansion of the pre-ionized plasma into the jet experiment chamber. The plasma transitioned from an ionizing phase with depressed neutral emission to a recombining phase with enhanced emission during the course of the experiment, causing fast camera images to be a poor indicator of the density distribution. Under certain conditions, the total visible and infrared brightness and the downstream ion density both increased after the RF power was turned off. The time-dependent emission patterns were used for an indirect measurement of the neutral gas pressure. The low-mass jets formed with the aid of the pre-ionization system were extremely narrow and collimated near the electrodes, with peak density exceeding that of jets created without pre-ionization. The initial neutral gas distribution prior to plasma breakdown was found to be critical in determining the ultimate jet structure. The visible radius of the dense central jet column was several times narrower than the axial current channel

A Low Power Consumption Algorithm for Efficient Energy Consumption in ZigBee Motes.

Science.gov (United States)

Vaquerizo-Hdez, Daniel; Muñoz, Pablo; R-Moreno, María D; F Barrero, David

2017-09-22

Wireless Sensor Networks (WSNs) are becoming increasingly popular since they can gather information from different locations without wires. This advantage is exploited in applications such as robotic systems, telecare, domotic or smart cities, among others. To gain independence from the electricity grid, WSNs devices are equipped with batteries, therefore their operational time is determined by the time that the batteries can power on the device. As a consequence, engineers must consider low energy consumption as a critical objective to design WSNs. Several approaches can be taken to make efficient use of energy in WSNs, for instance low-duty-cycling sensor networks (LDC-WSN). Based on the LDC-WSNs, we present LOKA, a LOw power Konsumption Algorithm to minimize WSNs energy consumption using different power modes in a sensor mote. The contribution of the work is a novel algorithm called LOKA that implements two duty-cycling mechanisms using the end-device of the ZigBee protocol (of the Application Support Sublayer) and an external microcontroller (Cortex M0+) in order to minimize the energy consumption of a delay tolerant networking. Experiments show that using LOKA, the energy required by the sensor device is reduced to half with respect to the same sensor device without using LOKA.

A Low Power Consumption Algorithm for Efficient Energy Consumption in ZigBee Motes

Directory of Open Access Journals (Sweden)

Daniel Vaquerizo-Hdez

2017-09-01

Full Text Available Wireless Sensor Networks (WSNs are becoming increasingly popular since they can gather information from different locations without wires. This advantage is exploited in applications such as robotic systems, telecare, domotic or smart cities, among others. To gain independence from the electricity grid, WSNs devices are equipped with batteries, therefore their operational time is determined by the time that the batteries can power on the device. As a consequence, engineers must consider low energy consumption as a critical objective to design WSNs. Several approaches can be taken to make efficient use of energy in WSNs, for instance low-duty-cycling sensor networks (LDC-WSN. Based on the LDC-WSNs, we present LOKA, a LOw power Konsumption Algorithm to minimize WSNs energy consumption using different power modes in a sensor mote. The contribution of the work is a novel algorithm called LOKA that implements two duty-cycling mechanisms using the end-device of the ZigBee protocol (of the Application Support Sublayer and an external microcontroller (Cortex M0+ in order to minimize the energy consumption of a delay tolerant networking. Experiments show that using LOKA, the energy required by the sensor device is reduced to half with respect to the same sensor device without using LOKA.

On the principles of the determination of the safe shut-down earthquake for nuclear power plants in Austria

International Nuclear Information System (INIS)

Drimmel, J.

1976-01-01

At present no legal guide lines exist in Austria for the determination of the Safe Shut-Down Earthquake. According to experience, the present requirements for a nuclear power plant site are the following: It must be free of marked tectonic faults and it must never have been situated within the epicentral region of a strong earthquake. The maximum expected earthquake and the Safe Shut-Down Earthquake respectively, are fixed by the aid of a frequency map of strong earthquakes and a map of extreme earthquake intensities in Austria based on macroseismic data since 1201 A.D. The corresponding values of acceleration will be prescribed according to the state of science, but must at least be 0.10 g for the horizontal and 0.05 g for the vertical component of acceleration at the basement

Specifications, Pre-Experimental Predictions, and Test Plate Characterization Information for the Prometheus Critical Experiments

International Nuclear Information System (INIS)

ML Zerkle; ME Meyers; SM Tarves; JJ Powers

2006-01-01

This report provides specifications, pre-experimental predictions, and test plate characterization information for a series of molybdenum (Mo), niobium (Nb), rhenium (Re), tantalum (Ta), and baseline critical experiments that were developed by the Naval Reactors Prime Contractor Team (NRPCT) for the Prometheus space reactor development project. In March 2004, the Naval Reactors program was assigned the responsibility to develop, design, deliver, and operationally support civilian space nuclear reactors for NASA's Project Prometheus. The NRPCT was formed to perform this work and consisted of engineers and scientists from the Naval Reactors (NR) Program prime contractors: Bettis Atomic Power Laboratory, Knolls Atomic Power Laboratory (KAPL), and Bechtel Plant Machinery Inc (BPMI). The NRPCT developed a series of clean benchmark critical experiments to address fundamental uncertainties in the neutron cross section data for Mo, Nb, Re, and Ta in fast, intermediate, and mixed neutron energy spectra. These experiments were to be performed by Los Alamos National Laboratory (LANL) using the Planet vertical lift critical assembly machine and were designed with a simple, geometrically clean, cylindrical configuration consisting of alternating layers of test, moderator/reflector, and fuel materials. Based on reprioritization of missions and funding within NASA, Naval Reactors and NASA discontinued their collaboration on Project Prometheus in September 2005. One critical experiment and eighteen subcritical handstacking experiments were completed prior to the termination of work in September 2005. Information on the Prometheus critical experiments and the test plates produced for these experiments are expected to be of value to future space reactor development programs and to integral experiments designed to address the fundamental neutron cross section uncertainties for these refractory metals. This information is being provided as an orderly closeout of NRPCT work on Project

Critical power characteristics in 37-rod tight lattice bundles under transient conditions

International Nuclear Information System (INIS)

Liu, Wei; Kureta, Masatoshi; Tamai, Hidesada; Ohnuki, Akira; Akimoto, Hajime

2007-01-01

Critical power characteristics in the postulated abnormal transient processes that may be possibly met in the operation of Innovative Water Reactor for Flexible Fuel Cycle (FLWR) were investigated for the design of the FLWR core. Transient Boiling Transition (BT) tests were carried out using two sets of 37-rod tight lattice rod bundles (rod diameter: 13 mm; rod clearance: 1.3 mm or 1.0 mm) at Japan Atomic Energy Agency (JAEA) under the conditions covering the FLWR operating condition (P ex =7.2 MPa, T in =556 K) for mass velocity G=400-800 kg/(m 2 s). For the postulated power increase and flow decrease transients, no obvious change of the critical power against the steady one was observed. The traditional quasi-steady characteristic was confirmed to be working for the postulated power increase and flow decrease transients. The experiments were analyzed with TRAC-BF1 code, where the JAEA newest critical power correlation for the tight lattice rod bundles was implemented for the BT judgment. The TRAC-BF1 code showed good prediction for the occurrence or the non occurrence of the BT and for the exact BT starting time. The tranditional quasi-steady state prediction of the BT in transient process was confirmed to be applicable for the postulated abnormal transient processes in the tight lattice rod bundles. (author)

Operating experience with BWR nuclear power

International Nuclear Information System (INIS)

Bonsdorf, Magnus von.

1986-01-01

The two-unit nuclear power station in Olkiluoto on the western coast of Finland produces about 20 per cent of the electricity consumption of the country. The first unit, TVO-I was first connected to the national grid in September 1978 and TVO-II in February 1980. The original rated power output of each unit was 660 MWe, corresponding to the thermal power of 2000 MW from the reactor. Technical modifications allowed the power to be uprated by 8%. The operating statistics (load factors etc.) are given and the outage experience discussed. The radiological history shows very low radioactivity and dose levels have been maintained at the plant. (UK)

Improvement of Wearable Power Assist Wear for Low Back Support using Pneumatic Actuator

Science.gov (United States)

Cho, Feifei; Sugimoto, Riku; Noritsugu, Toshiro; Li, Xiangpan

2017-10-01

This study focuses on developing a safe, lightweight, power assist device that can be worn by people who like caregivers during lifting or static holding tasks to prevent low back pain (LBP). Therefore in consideration of their flexibility, light weight, and large force to weight ratio we have developed a Wearable Power Assist Wear for caregivers, two types of pneumatic actuators are employed in assisting low back movement for their safety and comfort. The device can be worn directly on the body like normal clothing. Because there is no rigid exoskeleton frame structure, it is lightweight and user friendly. In this paper, we proposed the new type of the wearable power assist wear and improved the controller of control system.

ICC Experiment Performance Improvement through Advanced Feedback Controllers for High-Power Low-Cost Switching Power Amplifiers

International Nuclear Information System (INIS)

Nelson, Brian A.

2006-01-01

Limited resources force most smaller fusion energy research experiments to have little or no feedback control of their operational parameters, preventing achievement of their full operational potential. Recent breakthroughs in high-power switching technologies have greatly reduced feedback-controlled power supply costs, primarily those classified as switching power amplifiers. However, inexpensive and flexible controllers for these power supplies have not been developed. A uClinux-based micro-controller (Analog Devices Blackfin BF537) was identified as having the capabilities to form the base of a digital control system for switching power amplifiers. A control algorithm was created, and a Linux character device driver was written to realize the algorithm. The software and algorithm were successfully tested on a switching power amplifier and magnetic field coil using University of Washington (subcontractor) resources

Construction of STACY (Static Experiment Critical Facility)

International Nuclear Information System (INIS)

Murakami, Kiyonobu; Onodera, Seiji; Hirose, Hideyuki

1998-08-01

Two critical assemblies, STACY (Static Experiment Critical Facility) and TRACY (Transient Experiment Critical Facility), were constructed in NUCEF (Nuclear Fuel Cycle Safety Engineering Research Facility) to promote researches on the criticality safety at a reprocessing facility. STACY aims at providing critical data of uranium nitrate solution, plutonium nitrate solution and their mixture while varying concentration of solution fuel, core tank shape and size and neutron reflecting condition. STACY achieved first criticality in February 1995, and passed the licensing inspection by STA (Science and Technology Agency of Japan) in May. After that a series of critical experiments commenced with 10 w/o enriched uranium solution. This report describes the outline of STACY at the end of FY 1996. (author)

Emergency Power For Critical Items

Science.gov (United States)

Young, William R.

2009-07-01

Natural disasters, such as hurricanes, floods, tornados, and tsunami, are becoming a greater problem as climate change impacts our environment. Disasters, whether natural or man made, destroy lives, homes, businesses and the natural environment. Such disasters can happen with little or no warning, leaving hundreds or even thousands of people without medical services, potable water, sanitation, communications and electrical services for up to several weeks. In our modern world, the need for electricity has become a necessity. Modern building codes and new disaster resistant building practices are reducing the damage to homes and businesses. Emergency gasoline and diesel generators are becoming common place for power outages. Generators need fuel, which may not be available after a disaster, but Photovoltaic (solar-electric) systems supply electricity without petroleum fuel as they are powered by the sun. Photovoltaic (PV) systems can provide electrical power for a home or business. PV systems can operate as utility interactive or stand-alone with battery backup. Determining your critical load items and sizing the photovoltaic system for those critical items, guarantees their operation in a disaster.

Development of modular scalable pulsed power systems for high power magnetized plasma experiments

Science.gov (United States)

Bean, I. A.; Weber, T. E.; Adams, C. S.; Henderson, B. R.; Klim, A. J.

2017-10-01

New pulsed power switches and trigger drivers are being developed in order to explore higher energy regimes in the Magnetic Shock Experiment (MSX) at Los Alamos National Laboratory. To achieve the required plasma velocities, high-power (approx. 100 kV, 100s of kA), high charge transfer (approx. 1 C), low-jitter (few ns) gas switches are needed. A study has been conducted on the effects of various electrode geometries and materials, dielectric media, and triggering strategies; resulting in the design of a low-inductance annular field-distortion switch, optimized for use with dry air at 90 psig, and triggered by a low-jitter, rapid rise-time solid-state Linear Transformer Driver. The switch geometry and electrical characteristics are designed to be compatible with Syllac style capacitors, and are intended to be deployed in modular configurations. The scalable nature of this approach will enable the rapid design and implementation of a wide variety of high-power magnetized plasma experiments. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration. Approved for unlimited release, LA-UR-17-2578.

Disparities in abortion experience and access to safe abortion ...

African Journals Online (AJOL)

In Ghana, abortion mortality constitutes 11% of maternal mortality. Empirical studies on possible disparities in abortion experience and access to safe abortion services are however lacking. Based on a retrospective survey of 1,370 women aged 15-49 years in two districts in Ghana, this paper examines disparities in ...

The regulatory framework for safe decommissioning of nuclear power plants in Korea

International Nuclear Information System (INIS)

Sangmyeon Ahn; Jungjoon Lee; Chanwoo Jeong; Kyungwoo Choi

2013-01-01

We are having 23 units of nuclear power plants in operation and 5 units of nuclear power plants under construction in Korea as of September 2012. However, we don't have any experience on shutdown permanently and decommissioning of nuclear power plants. There are only two research reactors being decommissioned since 1997. It is realized that improvement of the regulatory framework for decommissioning of nuclear facilities has been emphasized constantly from the point of view of IAEA's safety standards. It is also known that IAEA will prepare the safety requirement on decommissioning of facilities; its title is the Safe Decommissioning of Facilities, General Safety Requirement Part 6. According to the result of IAEA's Integrated Regulatory Review Service (IRRS) mission to Korea in 2011, it was recommended that the regulatory framework should require decommissioning plans for nuclear installations to be constructed and operated and these plans should be updated periodically. In addition, after the Fukushima nuclear disaster in Japan in March of 2011, preparedness for early decommissioning caused by an unexpected severe accident became important issues and concerns. In this respect, it is acknowledged that the regulatory framework for decommissioning of nuclear facilities in Korea need to be improved. First of all, we focus on identifying the current status and relevant issues of regulatory framework for decommissioning of nuclear power plants compared to the IAEA's safety standards in order to achieve our goal. And then the plan is established for improvement of regulatory framework for decommissioning of nuclear power plants in Korea. It is expected that if the things will go forward as planned, the revised regulatory framework for decommissioning could enhance the safety regime on the decommissioning of nuclear power plants in Korea in light of international standards. (authors)

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

Remarks on building of low-powered airplanes

Science.gov (United States)

Langsdorff, Werner V

1924-01-01

If the low-powered airplane is to be used advantageously by private individuals, the most important consideration is a smaller fuel consumption and, hence, a lower engine power. From experiments with gliders, it appears entirely possible, by utilizing ascending winds (on the weather side of mountains and those generated by the heat of the sun) and by employing engine flight intermittently, as required to fly long distances over land.

A single lithium-ion battery protection circuit with high reliability and low power consumption

International Nuclear Information System (INIS)

Jiang Jinguang; Li Sen

2014-01-01

A single lithium-ion battery protection circuit with high reliability and low power consumption is proposed. The protection circuit has high reliability because the voltage and current of the battery are controlled in a safe range. The protection circuit can immediately activate a protective function when the voltage and current of the battery are beyond the safe range. In order to reduce the circuit's power consumption, a sleep state control circuit is developed. Additionally, the output frequency of the ring oscillation can be adjusted continuously and precisely by the charging capacitors and the constant-current source. The proposed protection circuit is fabricated in a 0.5 μm mixed-signal CMOS process. The measured reference voltage is 1.19 V, the overvoltage is 4.2 V and the undervoltage is 2.2 V. The total power is about 9 μW. (semiconductor integrated circuits)

The Zeus Copper/Uranium Critical Experiment at NCERC

International Nuclear Information System (INIS)

Sanchez, Rene G.; Hayes, David K.; Bounds, John Alan; Jackman, Kevin R.; Goda, Joetta M.

2012-01-01

A critical experiment was performed to provide nuclear data in a non-thermal neutron spectrum and to reestablish experimental capability relevant to Stockpile Stewardship and Technical Nuclear Forensic programs. Irradiation foils were placed at specific locations in the Zeus all oralloy critical experiment to obtain fission ratios. These ratios were compared with others from other critical assemblies to assess the degree of softness in the neutron spectrum. This critical experiment was performed at the National Criticality Experiments Research Center (NCERC) in Nevada.

Flow-Boiling Critical Heat Flux Experiments Performed in Reduced Gravity

Science.gov (United States)

Hasan, Mohammad M.; Mudawar, Issam

2005-01-01

Poor understanding of flow boiling in microgravity has recently emerged as a key obstacle to the development of many types of power generation and advanced life support systems intended for space exploration. The critical heat flux (CHF) is perhaps the most important thermal design parameter for boiling systems involving both heatflux-controlled devices and intense heat removal. Exceeding the CHF limit can lead to permanent damage, including physical burnout of the heat-dissipating device. The importance of the CHF limit creates an urgent need to develop predictive design tools to ensure both the safe and reliable operation of a two-phase thermal management system under the reduced-gravity (like that on the Moon and Mars) and microgravity environments of space. At present, very limited information is available on flow-boiling heat transfer and the CHF under these conditions.

Gas Bearing Control for Safe Operation in Critical Speed Regions - Experimental Verification

DEFF Research Database (Denmark)

Theisen, Lukas R. S.; Niemann, Hans H.; Galeazzi, Roberto

2015-01-01

supported by gas bearings to extend their operating range. Using H∞-design methods, active lubrication techniques are proposed to enhance the damping, which in turn reduces the vibrations to a desired safe level. The control design is validated experimentally on a laboratory test rig, and shown to allow...... and deceleration patterns and avoidance of operation near the critical speeds, which is a limiting factor during operation, specially during run-downs. An approach for reducing the vibrations is by feedback controlled lubrication. This paper addresses the challenge of reducing vibrations in rotating machines...

Critical defect size assessment in pipelines on a nuclear power plant

Directory of Open Access Journals (Sweden)

Dimova Galya

2018-01-01

Full Text Available In many energy industry structures, pipeline systems are subject to the impact of mechanical forces, moments of forces and fluid flows of high pressure and temperature. These load factors cause defects in the pipeline metal. As the years of operation increase, defects may occur and grow, which may lead to the destruction of pipeline walls. Special measures have been planned and implemented to ensure the safe operation of high-energy facilities. This study focused on pipelines and nozzles of nuclear power plant equipment with bimetal welded joints on which the size of critical defects was assessed. The base of assessment covers material properties, temperature and stress fields, fracture mechanics calculations. This study involves developing of finite element models and implementing simulations on them in order to obtain temperature fields and determine the stress-strain state of the component.

Lessons learned from commercial experience with nuclear plant decontamination to safe storage

International Nuclear Information System (INIS)

Fischer, S.R.; Partain, W.L.; Sype, T.

1995-01-01

The Department of Energy (DOE) has successfully performed decontamination and decommissioning (D ampersand D) on many production reactors it. DOE now has the challenge of performing D ampersand D on a wide variety of other nuclear facilities. Because so many facilities are being closed, it is necessary to place many of them into a safe-storage status before conducting D ampersand D-for perhaps as much as 20 yr. The challenge is to achieve this safe-storage condition in a cost-effective manner while remaining in compliance with applicable regulations. The DOE Office of Environmental Management, Office of Transition and Management, commissioned a lessons learned study of commercial experience with safe storage and transition to D ampersand D. Although the majority of the commercial experience has been with reactors, many of the lessons learned presented in this paper are directly applicable to transitioning the DOE Weapons Complex

The experiences to improve plant performance and reliability of Ko-Ri nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Kang, Ho Weon [Korea Electric Power Corp. Ko-Ri nuclear power division, Ko-Ri (Korea, Republic of)

1998-07-01

This paper provides a discussion of the lessons learned from operational experience and the future plans to improve performance of the Ko-Ri plant. To operate nuclear power plants safely with good performance is the only way to mitigate the negative image of nuclear power generation to the public and to enhance the economical benefit compared to other electrical generation method. Therefore, in a continuous effort to overcome a negative challenge from outside, we have driven an aggressive 'OCTF' campaign as part of safety. As a result of our efforts, the following remarkable achievements have been accomplished. (1) 3 times of OCTF during recent three years (2) Selected twice as a top notch power plant on the list of NEI magazine in terms of plant capacity factor (3) No scram recorded in 1997 for all 4 units at Ko-Ri site. Ko-Ri is now undergoing the large scale plant betterment projects for retaking-off our operating performance to the level of new challenge target. Such improvement of critical components in the reactor coolant system and turbine system greatly contribute to increase the safety and reliability of the plant and to shortening of the planned outage period as well as to reduction of radiation exposure and radwaste. (Cho, G. S.). 5 tabs., 10 figs.

Plutonium safe handling

International Nuclear Information System (INIS)

Tvehlov, Yu.

2000-01-01

The abstract, prepared on the basis of materials of the IAEA new leadership on the plutonium safe handling and its storage (the publication no. 9 in the Safety Reports Series), aimed at presenting internationally acknowledged criteria on the radiation danger evaluation and summarizing the experience in the safe management of great quantities of plutonium, accumulated in the nuclear states, is presented. The data on the weapon-class and civil plutonium, the degree of its danger, the measures for provision of its safety, including the data on accident radiation consequences with the fission number 10 18 , are presented. The recommendations, making it possible to eliminate the super- criticality danger, as well as ignition and explosion, to maintain the tightness of the facility, aimed at excluding the radioactive contamination and the possibility of internal irradiation, to provide for the plutonium security, physical protection and to reduce irradiation are given [ru

Planning the Unplanned Experiment: Towards Assessing the Efficacy of Standards for Safety-Critical Software

Science.gov (United States)

Graydon, Patrick J.; Holloway, C. M.

2015-01-01

Safe use of software in safety-critical applications requires well-founded means of determining whether software is fit for such use. While software in industries such as aviation has a good safety record, little is known about whether standards for software in safety-critical applications 'work' (or even what that means). It is often (implicitly) argued that software is fit for safety-critical use because it conforms to an appropriate standard. Without knowing whether a standard works, such reliance is an experiment; without carefully collecting assessment data, that experiment is unplanned. To help plan the experiment, we organized a workshop to develop practical ideas for assessing software safety standards. In this paper, we relate and elaborate on the workshop discussion, which revealed subtle but important study design considerations and practical barriers to collecting appropriate historical data and recruiting appropriate experimental subjects. We discuss assessing standards as written and as applied, several candidate definitions for what it means for a standard to 'work,' and key assessment strategies and study techniques and the pros and cons of each. Finally, we conclude with thoughts about the kinds of research that will be required and how academia, industry, and regulators might collaborate to overcome the noted barriers.

Benchmarking criticality safety calculations with subcritical experiments

International Nuclear Information System (INIS)

Mihalczo, J.T.

1984-06-01

Calculation of the neutron multiplication factor at delayed criticality may be necessary for benchmarking calculations but it may not be sufficient. The use of subcritical experiments to benchmark criticality safety calculations could result in substantial savings in fuel material costs for experiments. In some cases subcritical configurations could be used to benchmark calculations where sufficient fuel to achieve delayed criticality is not available. By performing a variety of measurements with subcritical configurations, much detailed information can be obtained which can be compared directly with calculations. This paper discusses several measurements that can be performed with subcritical assemblies and presents examples that include comparisons between calculation and experiment where possible. Where not, examples from critical experiments have been used but the measurement methods could also be used for subcritical experiments

Low Power Consumption Wireless Sensor Communication System Integrated with an Energy Harvesting Power Source

OpenAIRE

Vlad MARSIC; Alessandro GIULIANO; Meiling ZHU

2013-01-01

This paper presents the testing results of a wireless sensor communication system with low power consumption integrated with an energy harvesting power source. The experiments focus on the system’s capability to perform continuous monitoring and to wirelessly transmit the data acquired from the sensors to a user base station, for realization of completely battery-free wireless sensor system. Energy harvesting technologies together with system design optimization for power consumption minimiza...

Operating Experience at the Aagesta Nuclear Power Station

Energy Technology Data Exchange (ETDEWEB)

Sandstroem, S [ed.

1966-09-15

Sweden's first nuclear power reactor Agesta, achieved criticality on July 17, 1963. Full power (65 MW{sub t}) was attained on March 20, 1964. Aagesta is a heavy water cooled and moderated pressure vessel reactor used for production of electricity as well as for district heating. The design, assembly and construction etc, of the reactor was described in detail in a staff report by AB Atomenergi, 'The Aagesta Nuclear Power Station' edited by B McHugh, which was published in September, 1964. In the book experiences from the commissioning and the first operation of the reactor were reported as well as findings from the extensive reactor physics studies made during this period. The report now presented is written by members of the operating team at Aagesta since its start. It reflects in general the experiences up to the end of 1965. The Aagesta Log, however, covers the period up to the normal summer stop 1966. The reactor has hitherto produced 506,000 MWh power of which 48,700 MWh have been electric power. In July 1965 the responsibility for the reactor operation was taken over by the Swedish State Power Board from AB Atomenergi, which company had started the reactor and operated it until the summer break 1965.

Operating Experience at the Aagesta Nuclear Power Station

International Nuclear Information System (INIS)

Sandstroem, S.

1966-09-01

Sweden's first nuclear power reactor Agesta, achieved criticality on July 17, 1963. Full power (65 MW t ) was attained on March 20, 1964. Aagesta is a heavy water cooled and moderated pressure vessel reactor used for production of electricity as well as for district heating. The design, assembly and construction etc, of the reactor was described in detail in a staff report by AB Atomenergi, 'The Aagesta Nuclear Power Station' edited by B McHugh, which was published in September, 1964. In the book experiences from the commissioning and the first operation of the reactor were reported as well as findings from the extensive reactor physics studies made during this period. The report now presented is written by members of the operating team at Aagesta since its start. It reflects in general the experiences up to the end of 1965. The Aagesta Log, however, covers the period up to the normal summer stop 1966. The reactor has hitherto produced 506,000 MWh power of which 48,700 MWh have been electric power. In July 1965 the responsibility for the reactor operation was taken over by the Swedish State Power Board from AB Atomenergi, which company had started the reactor and operated it until the summer break 1965

Operating Experience at the Aagesta Nuclear Power Station

Energy Technology Data Exchange (ETDEWEB)

Sandstroem, S. (ed.)

1966-09-15

Sweden's first nuclear power reactor Agesta, achieved criticality on July 17, 1963. Full power (65 MW{sub t}) was attained on March 20, 1964. Aagesta is a heavy water cooled and moderated pressure vessel reactor used for production of electricity as well as for district heating. The design, assembly and construction etc, of the reactor was described in detail in a staff report by AB Atomenergi, 'The Aagesta Nuclear Power Station' edited by B McHugh, which was published in September, 1964. In the book experiences from the commissioning and the first operation of the reactor were reported as well as findings from the extensive reactor physics studies made during this period. The report now presented is written by members of the operating team at Aagesta since its start. It reflects in general the experiences up to the end of 1965. The Aagesta Log, however, covers the period up to the normal summer stop 1966. The reactor has hitherto produced 506,000 MWh power of which 48,700 MWh have been electric power. In July 1965 the responsibility for the reactor operation was taken over by the Swedish State Power Board from AB Atomenergi, which company had started the reactor and operated it until the summer break 1965.

Psychosocial aspect of safe operation in Japanese nuclear power plants

International Nuclear Information System (INIS)

Kuroda, Isao

1988-01-01

It is not easy to reveal the reasons of safe operation of N.P.P. because many complicated factors are interrelated. However, to clarify the effective factors of the recent safe operation of Japanese N.P.P. is the important thema of research to continue this condition and the more improved level. At present, the follwing factors can be pointed out; 1) Influential safety policy of regulatory structures. 2) Enthusiastic and careful company policy on N.P.P. safety. 3) Close and stable relationship of the industries with companies on research, training and maintenance. 4) Collaborated safety research among scientific facilities, companies and manufacturers. 5) Good organization and management for N.P.P. personnel. 6) Well organized training program in company and training facilities. 7) Highly motivated N.P.P. personnel with high educational background. 8) Company atmosphere on N.P.P. safety. 9) Public opinion on nuclear power safety. (author)

Wireless powering for low-power distributed sensors

Directory of Open Access Journals (Sweden)

Popović Zoya B.

2006-01-01

Full Text Available In this paper, an overview of the field of wireless powering is presented with an emphasis on low-power applications. Several rectenna elements and arrays are discussed in more detail: (1 a 10-GHz array for powering sensors in aircraft wings; (2 a single antenna in the 2.4-GHz ISM band for low-power assisted-living sensors; and (3 a broadband array for power harvesting in the 2-18GHz frequency range.

Critical experiments of JMTRC MEU cores

International Nuclear Information System (INIS)

Nagaoka, Y.; Takeda, K.; Shimakawa, S.; Koike, S.; Oyamada, R.

1984-01-01

The JMTRC, the critical facility of the Japan Materials Testing Reactor (JMTR), went critical on August 29, 1983, with 14 medium enriched uranium (MEU, 45%) fuel elements. Experiments are now being carried out to measure the change in various reactor characteristics between the previous HEU core and the new MEU fueled core. This paper describes the results obtained thus far on critical mass, excess reactivity, control rod worths and flux distribution, including preliminary neutronics calculations for the experiments using the SRAC code. (author)

Electron versus proton accelerator driven sub-critical system performance using TRIGA reactors at power

International Nuclear Information System (INIS)

Carta, M.; Burgio, N.; D'Angelo, A.; Santagata, A.; Petrovich, C.; Schikorr, M.; Beller, D.; Felice, L. S.; Imel, G.; Salvatores, M.

2006-01-01

This paper provides a comparison of the performance of an electron accelerator-driven experiment, under discussion within the Reactor Accelerator Coupling Experiments (RACE) Project, being conducted within the U.S. Dept. of Energy's Advanced Fuel Cycle Initiative (AFCI), and of the proton-driven experiment TRADE (TRIGA Accelerator Driven Experiment) originally planned at ENEA-Casaccia in Italy. Both experiments foresee the coupling to sub-critical TRIGA core configurations, and are aimed to investigate the relevant kinetic and dynamic accelerator-driven systems (ADS) core behavior characteristics in the presence of thermal reactivity feedback effects. TRADE was based on the coupling of an upgraded proton cyclotron, producing neutrons via spallation reactions on a tantalum (Ta) target, with the core driven at a maximum power around 200 kW. RACE is based on the coupling of an Electron Linac accelerator, producing neutrons via photoneutron reactions on a tungsten-copper (W-Cu) or uranium (U) target, with the core driven at a maximum power around 50 kW. The paper is focused on analysis of expected dynamic power response of the RACE core following reactivity and/or source transients. TRADE and RACE target-core power coupling coefficients are compared and discussed. (authors)

Critical heat fluxes in tubular fuel elements of nuclear power reactors

International Nuclear Information System (INIS)

Subbotin, V.I.; Alekseev, G.V.; Peskov, O.L.

1974-01-01

The results of the experiments carried out show that with appropriate choice of tube, type and dimensions of intensifier the attainment of critical conditions at certain parameters is not accompanied by sharp or considerable increases in temperature of the heat removing surface. Increase in power to above critical under these conditions does not lead to considerable variation in temperature either. Thus, it appears possible to change from heat removal by steam-water mixture to convective heat removal by wet steam without manifestation of intolerable temperature conditions of the heating surface (Fig. 6). A change to convective heat removal by wet steam is possible at different levels of heat fluxes which depend during constant conditions at the inlet on tube length and the degree of the disturbing influence on the flow. This is especially important since in principle the possibility arises for developing a power reactor with tubular fuel elements, in which a once-through cycle with steam superheat involving no intermediate separation can be realised

Experimental Study on Critical Power in a Hemispherical Narrow Gap

International Nuclear Information System (INIS)

Park, Rae-Joon; Ha, Kwang-Soon; Kim, Sang-Baik; Kim, Hee-Dong; Jeong, Ji-Hwan

2002-01-01

An experimental study of critical heat flux in gap (CHFG) has been performed to investigate the inherent cooling mechanism in a hemispherical narrow gap. The objectives of the CHFG test are to measure critical power from a critical heat removal rate through the hemispherical narrow gap using distilled water with experimental parameters of system pressure and gap width. The CHFG test results have shown that a countercurrent flow limitation (CCFL) brings about local dryout at the small edge region of the upper part and finally global dryout in a hemispherical narrow gap. Increases in the gap width and pressure lead to an increase in critical power. The measured values of critical power are lower than the predictions made by other empirical CHF correlations applicable to flat plate, annuli, and small spherical gaps. The measured data on critical power in the hemispherical narrow gaps have been correlated using nondimensional parameters with a range of approximately ±20%. The developed correlation has been expanded to apply the spherical geometry using the Siemens/KWU correlation

A compact, inherently safe liquid metal reactor plant concept for terrestrial defense power applications

International Nuclear Information System (INIS)

Magee, P.M.; Dubberley, A.E.; Lutz, D.E.; Palmer, R.S.

1987-01-01

A compact, inherently safe, liquid metal reactor concept based on the GE PRISM innovative LMR design has been developed for terrestrial defense power applications in the 2-50 MWe range. The concept uses a small, sodium-cooled, U-5%Zr metal fueled reactor contained within two redundant steel vessels. The core is designed to operate at a low power density and temperature (925 F) and can operate 30 years without refueling. One two primary coolant loops, depending upon the plant size, transport heat from the core to sodium-to-air, double-wall heat exchangers. Power is produced by a gas turbine operated in a closed ''bottoming'' cycle that employs intercoolers between the compressor stages and a recuperator. Inherent safety is provided by passive means only; operator action is not required to ensure plant safety even for events normally considered Beyond Design Basis Accidents. In addition to normal shutdown heat removal via the sodium-to-air heat exchangers, the design utilizes an inherently passive radiant vessel auxiliary cooling system similar to that designed for PRISM. The use of an air cycle gas turbine eliminates the cost and complexity of the sodium-water reactor pressure relief system required for a steam cycle sodium-cooled reactor

Holding Firm: Power, Push-Back, and Opportunities in Navigating the Liminal Space of Critical Qualitative Health Research.

Science.gov (United States)

Hart, Corinne; Poole, Jennifer M; Facey, Marcia E; Parsons, Janet A

2017-10-01

Critical qualitative health researchers typically occupy and navigate liminal academic spaces and statuses, with one foot planted in the arts and social sciences and the other in biomedical science. We are at once marginalized and empowered, and this liminality presents both challenges and opportunities. In this article, we draw on our experiences of being (often the lone) critical qualitative health scholars on thesis advisory committees and dissertation examinations, as well as our experiences of publishing and securing funding, to illuminate how power and knowledge relations create conditions that shape the nature of our roles. We share strategies we have developed for standing our theoretical and methodological ground. We discuss how we use the power of our liminality to hold firm, push back, and push forward, to ensure that critical qualitative research is not further relegated to the margins and its quality and integrity sustained.

Low power arcjet performance

Science.gov (United States)

Curran, Francis M.; Sarmiento, Charles J.

1990-01-01

An experimental investigation was performed to evaluate arcjet operation at low power. A standard, 1 kW, constricted arcjet was run using nozzles with three different constrictor diameters. Each nozzle was run over a range of current and mass flow rates to explore stability and performance in the low power regime. A standard pulse-width modulated power processor was modified to accommodate the high operating voltages required under certain conditions. Stable, reliable operation at power levels below 0.5 kW was obtained at efficiencies between 30 and 40 percent. The operating range was found to be somewhat dependent on constrictor geometry at low mass flow rates. Quasi-periodic voltage fluctuations were observed at the low power end of the operating envelope. The nozzle insert geometry was found to have little effect on the performance of the device. The observed performance levels show that specific impulse levels above 350 seconds can be obtained at the 0.5 kW power level.

Proposed plan for critical experiments supporting thorium fuel cycle development

International Nuclear Information System (INIS)

Gore, B.F.

1978-09-01

A preliminary plan is proposed for critical experiments to provide data needed for the recycle of thorium based nuclear fuels. The sequence of experimentation starts with well moderated solutions followed by highly concentrated low moderated solutions. It then progresses through lattices moderated by water, by water plus soluble poisons, and by fissile solutions, to solutions poisoned by raschig rings and soluble poisons. Final experiments would treat lattices moderated by poisoned fissile solution, and arrays of stored fissile units

Coaxial wet-spun yarn supercapacitors for high-energy density and safe wearable electronics

Science.gov (United States)

Kou, Liang; Huang, Tieqi; Zheng, Bingna; Han, Yi; Zhao, Xiaoli; Gopalsamy, Karthikeyan; Sun, Haiyan; Gao, Chao

2014-01-01

Yarn supercapacitors have great potential in future portable and wearable electronics because of their tiny volume, flexibility and weavability. However, low-energy density limits their development in the area of wearable high-energy density devices. How to enhance their energy densities while retaining their high-power densities is a critical challenge for yarn supercapacitor development. Here we propose a coaxial wet-spinning assembly approach to continuously spin polyelectrolyte-wrapped graphene/carbon nanotube core-sheath fibres, which are used directly as safe electrodes to assembly two-ply yarn supercapacitors. The yarn supercapacitors using liquid and solid electrolytes show ultra-high capacitances of 269 and 177 mF cm−2 and energy densities of 5.91 and 3.84 μWh cm−2, respectively. A cloth supercapacitor superior to commercial capacitor is further interwoven from two individual 40-cm-long coaxial fibres. The combination of scalable coaxial wet-spinning technology and excellent performance of yarn supercapacitors paves the way to wearable and safe electronics. PMID:24786366

Coaxial wet-spun yarn supercapacitors for high-energy density and safe wearable electronics

Science.gov (United States)

Kou, Liang; Huang, Tieqi; Zheng, Bingna; Han, Yi; Zhao, Xiaoli; Gopalsamy, Karthikeyan; Sun, Haiyan; Gao, Chao

2014-05-01

Yarn supercapacitors have great potential in future portable and wearable electronics because of their tiny volume, flexibility and weavability. However, low-energy density limits their development in the area of wearable high-energy density devices. How to enhance their energy densities while retaining their high-power densities is a critical challenge for yarn supercapacitor development. Here we propose a coaxial wet-spinning assembly approach to continuously spin polyelectrolyte-wrapped graphene/carbon nanotube core-sheath fibres, which are used directly as safe electrodes to assembly two-ply yarn supercapacitors. The yarn supercapacitors using liquid and solid electrolytes show ultra-high capacitances of 269 and 177 mF cm-2 and energy densities of 5.91 and 3.84 μWh cm-2, respectively. A cloth supercapacitor superior to commercial capacitor is further interwoven from two individual 40-cm-long coaxial fibres. The combination of scalable coaxial wet-spinning technology and excellent performance of yarn supercapacitors paves the way to wearable and safe electronics.

Critical and sub-critical experiments on U-BeO lattices

International Nuclear Information System (INIS)

Benoist, P.; Gourdon, Ch.; Martelly, J.; Sagot, M.; Wanner, G.

1958-01-01

Sub-critical experiments have allowed us to measure the material buckling of uranium natural oxide of beryllium lattices with a grid of 15 cm, and made up of uranium bars measuring 2.60 - 2.92 - 3.56 and 4.40 cm of diameter. A critical experiment has then been conducted with hollow 1.35 per cent enriched uranium bars. A study of U-BeO 18.03 cm grid lattices is at present being conducted. (author) [fr

SLOWPOKE

International Nuclear Information System (INIS)

Law, Charles.

1979-01-01

The SLOWPOKE (Safe Low Power Critical Experiment) reactor was developed by AECL at Whiteshell and Chalk River between 1968 and 1970. It is a neutron-producing reactor of low power with minimal fuel, shielding, and cooling requirements and intrinsic safety. Four Canadian universities and one German one have acquired SLOWPOKE reactors for neutron activation analyses and for student research in nuclear engineering and reactor physics. (LL)

Critical experiments facility and criticality safety programs at JAERI

International Nuclear Information System (INIS)

Kobayashi, Iwao; Tachimori, Shoichi; Takeshita, Isao; Suzaki, Takenori; Miyoshi, Yoshinori; Nomura, Yasushi

1985-10-01

The nuclear criticality safety is becoming a key point in Japan in the safety considerations for nuclear installations outside reactors such as spent fuel reprocessing facilities, plutonium fuel fabrication facilities, large scale hot alboratories, and so on. Especially a large scale spent fuel reprocessing facility is being designed and would be constructed in near future, therefore extensive experimental studies are needed for compilation of our own technical standards and also for verification of safety in a potential criticality accident to obtain public acceptance. Japan Atomic Energy Research Institute is proceeding a construction program of a new criticality safety experimental facility where criticality data can be obtained for such solution fuels as mainly handled in a reprocessing facility and also chemical process experiments can be performed to investigate abnormal phenomena, e.g. plutonium behavior in solvent extraction process by using pulsed colums. In FY 1985 detail design of the facility will be completed and licensing review by the government would start in FY 1986. Experiments would start in FY 1990. Research subjects and main specifications of the facility are described. (author)

The button effect of CANFLEX bundle on the critical heat flux and critical channel power

Energy Technology Data Exchange (ETDEWEB)

Park, Joo Hwan; Jun, Jisu; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G R; Bullock, D E; Inch, W [Atomic Energy of Canada Limited, Ontario (Canada)

1998-12-31

A CANFLEX (CANdu FLEXible fuelling) 43-element bundle has developed for a CANDU-6 reactor as an alternative of 37-element fuel bundle. The design has two diameter elements (11.5 and 13.5 mm) to reduce maximum element power rating and buttons to enhance the critical heat flux (CHF), compared with the standard 37-element bundle. The freon CHF experiments have performed for two series of CANFLEX bundles with and without buttons with a modelling fluid as refrigerant R-134a and axial uniform heat flux condition. Evaluating the effects of buttons of CANFLEX bundle on CHF and Critical Channel Power (CCP) with the experimental results, it is shown that the buttons enhance CCP as well as CHF. All the CHF`s for both the CANFLEX bundles are occurred at the end of fuel channel with the high dryout quality conditions. The CHF enhancement ratio are increased with increase of dryout quality for all flow conditions and also with increase of mass flux only for high pressure conditions. It indicates that the button is a useful design for CANDU operating condition because most CHF flow conditions for CANDU fuel bundle are ranged to high dryout quality conditions. 5 refs., 11 figs. (Author)

The button effect of CANFLEX bundle on the critical heat flux and critical channel power

Energy Technology Data Exchange (ETDEWEB)

Park, Joo Hwan; Jun, Jisu; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Dimmick, G. R.; Bullock, D. E.; Inch, W. [Atomic Energy of Canada Limited, Ontario (Canada)

1997-12-31

A CANFLEX (CANdu FLEXible fuelling) 43-element bundle has developed for a CANDU-6 reactor as an alternative of 37-element fuel bundle. The design has two diameter elements (11.5 and 13.5 mm) to reduce maximum element power rating and buttons to enhance the critical heat flux (CHF), compared with the standard 37-element bundle. The freon CHF experiments have performed for two series of CANFLEX bundles with and without buttons with a modelling fluid as refrigerant R-134a and axial uniform heat flux condition. Evaluating the effects of buttons of CANFLEX bundle on CHF and Critical Channel Power (CCP) with the experimental results, it is shown that the buttons enhance CCP as well as CHF. All the CHF`s for both the CANFLEX bundles are occurred at the end of fuel channel with the high dryout quality conditions. The CHF enhancement ratio are increased with increase of dryout quality for all flow conditions and also with increase of mass flux only for high pressure conditions. It indicates that the button is a useful design for CANDU operating condition because most CHF flow conditions for CANDU fuel bundle are ranged to high dryout quality conditions. 5 refs., 11 figs. (Author)

Seismic-safe conditions of blasting near pressure pipe-lines during power installation construction

International Nuclear Information System (INIS)

Smolij, N.I.; Nikitin, A.S.

1980-01-01

Seismic-safe conditions for performing drill-blasting operations in the vicinity of underground gas pipelines when constructing thermal- or nuclear power plants are discussed. It is shown that, for the determination of seismic-safe parameters, of drill-blasting operations, the maximum permissible level of seismic loads should be specified taking into account the mechanical properties of the pipeline.metal, structural parameters of the gas pipeline and the pressure of the medium transported. Besides, the seismic effect of the blast should be considered with regard to particular conditions of blasting and rock properties. The equations and diagrams used in the calculation are given

Critical experiments with mixed oxide fuel

International Nuclear Information System (INIS)

Harris, D.R.

1997-01-01

This paper very briefly outlines technical considerations in performing critical experiments on weapons-grade plutonium mixed oxide fuel assemblies. The experiments proposed would use weapons-grade plutonium and Er 2 O 3 at various dissolved boron levels, and for specific fuel assemblies such as the ABBCE fuel assembly with five large water holes. Technical considerations described include the core, the measurements, safety, security, radiological matters, and licensing. It is concluded that the experiments are feasible at the Rensselaer Polytechnic Institute Reactor Critical Facility. 9 refs

Nuclear power experience

International Nuclear Information System (INIS)

1983-01-01

The International Conference on Nuclear Power Experience, organized by the International Atomic Energy Agency, was held at the Hofburg Conference Center, Vienna, Austria, from 13 to 17 September 1982. Almost 1200 participants and observers from 63 countries and 20 organizations attended the conference. The 239 papers presented were grouped under the following seven main topics: planning and development of nuclear power programmes; technical and economic experience of nuclear power production; the nuclear fuel cycle; nuclear safety experience; advanced systems; international safeguards; international co-operation. The proceedings are published in six volumes. The sixth volume contains a complete Contents of Volume 1 to 5, a List of Participants, Authors and Transliteration Indexes, a Subject Index and an Index of Papers by Number

Low Power/Low Voltage Interface Circuitry for Capacitive Sensors

DEFF Research Database (Denmark)

Furst, Claus Efdmann

This thesis focuses mainly on low power/low voltage interface circuits, implemented in CMOS, for capacitive sensors. A brief discussion of demands and possibilities for analog signal processing in the future is presented. Techniques for low power design is presented. This is done by analyzing power...... power consumption. It is shown that the Sigma-Delta modulator is advantageous when embedded in a feedback loop with a mechanical sensor. Here a micro mechanical capacitive microphone. Feedback and detection circuitry for a capacitive microphone is presented. Practical implementations of low power....../low voltage interface circuitry is presented. It is demonstrated that an amplifier optimized for a capacitive microphone implemented in a standard 0.7 micron CMOS technology competes well with a traditional JFET amplifier. Furthermore a low power/low voltage 3rd order Sigma-Delta modulator is presented...

Physics Experiments at the Agesta Power Station

Energy Technology Data Exchange (ETDEWEB)

Apelqvist, G [State Power Board, Stockholm (Sweden); Bliselius, P Aa; Blomberg, P E; Jonsson, E; Aakerhielm, F [AB Atomenergi, Nykoeping (Sweden)

1966-09-15

Part A. Dynamic measurements have been performed at the Aagesta reactor at power levels from 0.3 to 65 MW(th). The purposes of the experiments have been both to develop experimental methods and equipment for the dynamic studies and to measure the dynamic characteristics of the reactor in order to check the dynamic model. The experiments have been performed with four different perturbation functions: trapezoidal and step functions and two types of periodic multifrequency signals. Perturbations were introduced in the reactivity and in the load. The recordings were made of the responses of nuclear power, coolant inlet and outlet temperature and control rod position. The results are presented as step responses and transfer functions (Bode diagrams). Inmost cases the relative accuracy is {+-} 0.5 dB in amplitude and {+-} 5 deg in phase. The results from the experiments in general show rather good agreement with the results obtained from a dynamic model, which successively has been improved. Experience on reactor noise analysis based on measurements in the Agesta power reactor is discussed. It is shown that the noise measurements have given complementary dynamic information of the reactor. Part B. Static measurements of the physics parameters in the Agesta reactor are carried out to confirm theoretical methods for reactor calculations and to form a good basis for safe operation of the reactor. The reactivity worth of groups of control rods are determined with different methods and compared with calculations with the three-dimensional code HETERO. The excess reactivity as a function of burn up is obtained from the control rod positions. The temperature coefficient of the moderator is measured by lowering the moderator temperature at constant power and observing the change in control rod insertion. As burn up increases the experiments are repeated in order to follow the changes in the coefficient. The xenon poisoning effects are measured by changing the power level and

Physics Experiments at the Agesta Power Station

International Nuclear Information System (INIS)

Apelqvist, G.; Bliselius, P. Aa.; Blomberg, P.E.; Jonsson, E.; Aakerhielm, F.

1966-09-01

Part A. Dynamic measurements have been performed at the Aagesta reactor at power levels from 0.3 to 65 MW(th). The purposes of the experiments have been both to develop experimental methods and equipment for the dynamic studies and to measure the dynamic characteristics of the reactor in order to check the dynamic model. The experiments have been performed with four different perturbation functions: trapezoidal and step functions and two types of periodic multifrequency signals. Perturbations were introduced in the reactivity and in the load. The recordings were made of the responses of nuclear power, coolant inlet and outlet temperature and control rod position. The results are presented as step responses and transfer functions (Bode diagrams). Inmost cases the relative accuracy is ± 0.5 dB in amplitude and ± 5 deg in phase. The results from the experiments in general show rather good agreement with the results obtained from a dynamic model, which successively has been improved. Experience on reactor noise analysis based on measurements in the Agesta power reactor is discussed. It is shown that the noise measurements have given complementary dynamic information of the reactor. Part B. Static measurements of the physics parameters in the Agesta reactor are carried out to confirm theoretical methods for reactor calculations and to form a good basis for safe operation of the reactor. The reactivity worth of groups of control rods are determined with different methods and compared with calculations with the three-dimensional code HETERO. The excess reactivity as a function of burn up is obtained from the control rod positions. The temperature coefficient of the moderator is measured by lowering the moderator temperature at constant power and observing the change in control rod insertion. As burn up increases the experiments are repeated in order to follow the changes in the coefficient. The xenon poisoning effects are measured by changing the power level and

Simulation experience enhances physical therapist student confidence in managing a patient in the critical care environment.

Science.gov (United States)

Ohtake, Patricia J; Lazarus, Marcilene; Schillo, Rebecca; Rosen, Michael

2013-02-01

Rehabilitation of patients in critical care environments improves functional outcomes. This finding has led to increased implementation of intensive care unit (ICU) rehabilitation programs, including early mobility, and an associated increased demand for physical therapists practicing in ICUs. Unfortunately, many physical therapists report being inadequately prepared to work in this high-risk environment. Simulation provides focused, deliberate practice in safe, controlled learning environments and may be a method to initiate academic preparation of physical therapists for ICU practice. The purpose of this study was to examine the effect of participation in simulation-based management of a patient with critical illness in an ICU setting on levels of confidence and satisfaction in physical therapist students. A one-group, pretest-posttest, quasi-experimental design was used. Physical therapist students (N=43) participated in a critical care simulation experience requiring technical (assessing bed mobility and pulmonary status), behavioral (patient and interprofessional communication), and cognitive (recognizing a patient status change and initiating appropriate responses) skill performance. Student confidence and satisfaction were surveyed before and after the simulation experience. Students' confidence in their technical, behavioral, and cognitive skill performance increased from "somewhat confident" to "confident" following the critical care simulation experience. Student satisfaction was highly positive, with strong agreement the simulation experience was valuable, reinforced course content, and was a useful educational tool. Limitations of the study were the small sample from one university and a control group was not included. Incorporating a simulated, interprofessional critical care experience into a required clinical course improved physical therapist student confidence in technical, behavioral, and cognitive performance measures and was associated with high

Water chemistry technology. One of the key technologies for safe and reliable nuclear power plant operation

International Nuclear Information System (INIS)

Uchida, Shunsuke; Katsumura, Yosuke

2013-01-01

Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry should be simultaneously satisfied: (1) better reliability of reactor structures and fuel rods; (2) lower occupational exposure and (3) fewer radwaste sources. Various groups in academia have carried out basic research to support the technical bases of water chemistry in plants. The Research Committee on Water Chemistry of the Atomic Energy Society of Japan (AESJ), which has now been reorganized as the Division of Water Chemistry (DWC) of AESJ, has played important roles to promote improvements in water chemistry control, to share knowledge about and experiences with water chemistry control among plant operators and manufacturers and to establish common technological bases for plant water chemistry and then to transfer them to the next generation of plant workers engaged in water chemistry. Furthermore, the DWC has tried and succeeded arranging R and D proposals for further improvement in water chemistry control through roadmap planning. In the paper, major achievements in plant technologies and in basic research studies of water chemistry in Japan are reviewed. The contributions of the DWC to the long-term safe management of the damaged reactors at the Fukushima Daiichi Nuclear Power Plant until their decommissioning are introduced. (author)

Parametric analyses of planned flowing uranium hexafluoride critical experiments

Science.gov (United States)

Rodgers, R. J.; Latham, T. S.

1976-01-01

Analytical investigations were conducted to determine preliminary design and operating characteristics of flowing uranium hexafluoride (UF6) gaseous nuclear reactor experiments in which a hybrid core configuration comprised of UF6 gas and a region of solid fuel will be employed. The investigations are part of a planned program to perform a series of experiments of increasing performance, culminating in an approximately 5 MW fissioning uranium plasma experiment. A preliminary design is described for an argon buffer gas confined, UF6 flow loop system for future use in flowing critical experiments. Initial calculations to estimate the operating characteristics of the gaseous fissioning UF6 in a confined flow test at a pressure of 4 atm, indicate temperature increases of approximately 100 and 1000 K in the UF6 may be obtained for total test power levels of 100 kW and 1 MW for test times of 320 and 32 sec, respectively.

Low energy, high power injection in JT-60 NBI

International Nuclear Information System (INIS)

Mizuno, Makoto; Dairaku, Masayuki; Horiike, Hiroshi

1988-05-01

JT-60 neutral beam injector (JT-60 NBI) is designed to inject 20 MW neutral hydrogen beam at energies of 70 ∼ 100 keV and the injection power decreases significantly at low energies (∼40 keV). For the extention of operation region aiming at the low density plasma heating and achieving H-mode by plasma periphery heating, increment of the injection power at low beam energies was required. The single-stage acceleration system was investigated in advance at the Prototype Injector Unit. From this result, the total injection power of 17 MW at 40 keV, 48 A per source was expected at the JT-60 NBI. This system was adopted in the JT-60 NBI from June, 1987 to July, 1987 and 17.6 MW neutral beam injection power was achieved. In the NB heating experiment, the H-mode transition phenomena was observed in JT-60 plasma. (author)

On the experience of feeling powerful: perceived power moderates the effect of stereotype threat on women's math performance.

Science.gov (United States)

Van Loo, Katie J; Rydell, Robert J

2013-03-01

This research examined whether feeling powerful can eliminate the deleterious effect of stereotype threat (i.e., concerns about confirming a negative self-relevant stereotype) on women's math performance. In Experiments 1 and 2, priming women with high power buffered them from reduced math performance in response to stereotype threat instructions, whereas women in the low and control power conditions showed poorer math performance in response to threat. Experiment 3 found that working memory capacity is one mechanism through which power moderates the effect of threat on women's math performance. In the low and control power conditions, women showed reduced working memory capacity in response to stereotype threat, accounting for threat's effect on performance. In contrast, women in the high power condition did not show reductions in working memory capacity or math performance in response to threat. This work demonstrates that perceived power moderates stereotype threat-based performance effects and explains why this occurs.

Determinants of knowledge of critical danger signs, safe childbirth and immediate newborn care practices among auxiliary midwives: a cross sectional survey in Myanmar.

Science.gov (United States)

Than, Kyu Kyu; Morgan, Alison; Pham, Minh Duc; Beeson, James G; Luchters, Stanley

2017-07-05

The re-emergence of community-based health workers such as the auxiliary midwives (AMWs) in Myanmar, who are local female volunteers, has been an important strategy to address global health workforce shortages. The Myanmar government recommends one AMW for every village. The aim of this study is to investigate the current knowledge of critical danger signs and practices for safe childbirth and immediate newborn care of AMWs to inform potential task shifting of additional healthcare responsibilities. A cross-sectional survey was conducted from July 2015 to June 2016 in three hard-to-reach areas in Myanmar. Face-to-face interviews were conducted using a pretested questionnaire. Among 262 AMWs participating in the study, only 8% of AMWs were able to identify at least 80% of 20 critical danger signs. Factors associated with greater knowledge of critical danger signs included older age over 35 years (adjusted OR (AOR) 2.19, 95% CI 0.99 to 4.83), having received refresher training within the last year (AOR 2.20, 95% CI 1.21 to 4.01) and receiving adequate supervision (AOR 5.04, 95% CI 2.74 to 9.29). Those who employed all six safe childbirth and immediate newborn care practices were more likely to report greater knowledge of danger signs (AOR 2.81, 95% CI 1.50 to 5.26), adequate work supervision (AOR 3.18 95% CI 1.62 to 6.24) and less education (AOR 0.44, 95% CI 0.23 to 0.88). The low level of knowledge of critical danger signs and reported practices for safe childbirth identified suggest that an evaluation of the current AMW training and supervision programme needs to be revisited to ensure that existing practices, including recognition of danger signs, meet quality care standards before new interventions are introduced or new responsibilities given to AMWs. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Overview of Experiments for Physics of Fast Reactors from the International Handbooks of Evaluated Criticality Safety Benchmark Experiments and Evaluated Reactor Physics Benchmark Experiments

Energy Technology Data Exchange (ETDEWEB)

Bess, J. D.; Briggs, J. B.; Gulliford, J.; Ivanova, T.; Rozhikhin, E. V.; Semenov, M. Yu.; Tsibulya, A. M.; Koscheev, V. N.

2017-07-01

Overview of Experiments to Study the Physics of Fast Reactors Represented in the International Directories of Critical and Reactor Experiments John D. Bess Idaho National Laboratory Jim Gulliford, Tatiana Ivanova Nuclear Energy Agency of the Organisation for Economic Cooperation and Development E.V.Rozhikhin, M.Yu.Sem?nov, A.M.Tsibulya Institute of Physics and Power Engineering The study the physics of fast reactors traditionally used the experiments presented in the manual labor of the Working Group on Evaluation of sections CSEWG (ENDF-202) issued by the Brookhaven National Laboratory in 1974. This handbook presents simplified homogeneous model experiments with relevant experimental data, as amended. The Nuclear Energy Agency of the Organization for Economic Cooperation and Development coordinates the activities of two international projects on the collection, evaluation and documentation of experimental data - the International Project on the assessment of critical experiments (1994) and the International Project on the assessment of reactor experiments (since 2005). The result of the activities of these projects are replenished every year, an international directory of critical (ICSBEP Handbook) and reactor (IRPhEP Handbook) experiments. The handbooks present detailed models of experiments with minimal amendments. Such models are of particular interest in terms of the settlements modern programs. The directories contain a large number of experiments which are suitable for the study of physics of fast reactors. Many of these experiments were performed at specialized critical stands, such as BFS (Russia), ZPR and ZPPR (USA), the ZEBRA (UK) and the experimental reactor JOYO (Japan), FFTF (USA). Other experiments, such as compact metal assembly, is also of interest in terms of the physics of fast reactors, they have been carried out on the universal critical stands in Russian institutes (VNIITF and VNIIEF) and the US (LANL, LLNL, and others.). Also worth mentioning

A selection of problems related to safe working conditions in nuclear power plants

International Nuclear Information System (INIS)

Brunner, K.H.

1984-01-01

Two representative examples were chosen to demonstrate that the problems related to safe working conditions can be solved with work being prepared extensively and in detail taking into consideration radiation protection and conventional job safety measures and with qualified staff. Most of the job safety problems in nuclear power plants are pretty much the same as in conventional plants. Despite successful implementation of employment and radiation protection in nuclear power plants, improvements in detail are possible and make sense. (orig.) [de

New design procedure development of future reactor critical power estimation. (1) Practical design-by-analysis method for BWR critical power design correlation

International Nuclear Information System (INIS)

Yamamoto, Yasushi; Mitsutake, Toru

2007-01-01

For present BWR fuels, the full mock-up thermal-hydraulic test, such as the critical power measurement test, pressure drop measurement test and so on, has been needed. However, the full mock-up test required the high costs and large-scale test facility. At present, there are only a few test facilities to perform the full mock-up thermal-hydraulic test in the world. Moreover, for future BWR, the bundle size tends to be larger, because of reducing the plant construction costs and minimizing the routine check period. For instance, AB1600, improved ABWR, was proposed from Toshiba, whose bundle size was 1.2 times larger than the conventional BWR fuel size. It is too expensive and far from realistic to perform the full mock-up thermal-hydraulic test for such a large size fuel bundle. The new design procedure is required to realize the large scale bundle design development, especially for the future reactor. Therefore, the new design procedure, Practical Design-by-Analysis (PDBA) method, has been developed. This new procedure consists of the partial mock-up test and numerical analysis. At present, the subchannel analysis method based on three-fluid two-phase flow model only is a realistic choice. Firstly, the partial mock-up test is performed, for instance, the 1/4 partial mock-up bundle. Then, the first-step critical power correlation coefficients are evaluated with the measured data. The input data, such as the spacer effect model coefficient, on the subchannel analysis are also estimated with the data. Next, the radial power effect on the critical power of the full-bundle size was estimated with the subchannel analysis. Finally, the critical power correlation is modified by the subchannel analysis results. In the present study, the critical power correlation of the conventional 8x8 BWR fuel was developed with the PDBA method by 4x4 partial mock-up tests and the subchannel analysis code. The accuracy of the estimated critical power was 3.8%. The several themes remain to

Power generation from low-temperature heat source

Energy Technology Data Exchange (ETDEWEB)

Lakew, Amlaku Abie

2012-07-01

The potential of low-temperature heat sources for power production has been discussed for decades. The diversity and availability of low-temperature heat sources makes it interesting for power production. The thermodynamic power cycle is one of the promising technologies to produce electricity from low-temperature heat sources. There are different working fluids to be used in a thermodynamic power cycle. Working fluid selection is essential for the performance of the power cycle. Over the last years, different working fluid screening criteria have been used. In broad speaking the screening criteria can be grouped as thermodynamic performance, component size requirement, economic performance, safety and environmental impact. Screening of working fluids at different heat source temperatures (80-200 Celsius degrees) using thermodynamic performance (power output and exergy efficiency) and component size (heat exchanger and turbine) is investigated. It is found that the 'best' working fluid depends on the criteria used and heat source temperature level. Transcritical power cycles using carbon dioxide as a working fluid is studied to produce power at 100 Celsius degrees. Carbon dioxide is an environmentally friendly refrigerant. The global warming potential of carbon dioxide is 1. Furthermore, because of its low critical temperature (31 Celsius degrees), carbon dioxide can operate in a transcritical power cycle for lower heat source temperatures. A transcritical configuration avoids the problem of pinching which otherwise would happened in subcritical power cycle. In the process, better temperature matching is achieved and more heat is extracted. Thermodynamic analysis of transcritical cycle is performed; it is found that there is an optimal operating pressure for highest net power output. The pump work is a sizable fraction of the work produced by the turbine. The effect of efficiency deterioration of the pump and the turbine is compared. When the

Examination of Critical Length Effect in Copper Interconnects With Oxide and Low-k Dielectrics

International Nuclear Information System (INIS)

Thrasher, Stacye; Gall, Martin; Justison, Patrick; Hernandez, Richard; Kawasaki, Hisao; Capasso, Cristiano; Nguyen, Timothy

2004-01-01

As technology moves toward faster microelectronic devices with smaller feature sizes, copper is replacing aluminum-copper alloy and low-k dielectric is replacing oxide as the materials of choice for advanced interconnect integrations. Copper not only brings to the table the advantage of lower resistivity, but also exhibits better electromigration performance when compared to Al(Cu). Low-k dielectric materials are advantageous because they reduce power consumption and improve signal delay. Due to these advantages, the industry trend is moving towards integrating copper and low-k dielectric for high performance interconnects. The purpose of this study is to evaluate the critical length effect in single-inlaid copper interconnects and determine the critical product (jl)c, for a variety of integrations, examining the effect of ILD (oxide vs. low-k), geometry, and stress temperature

Multipurpose Masculinities: Gender and Power in Low Countries Histories of Masculinity

Directory of Open Access Journals (Sweden)

Stefan Dudink

2012-03-01

Full Text Available This article introduces the contributions to a BMGN - Low Countries Historical Review special issue on Low Countries masculinities. It outlines a shared theoretical framework that focuses on what historian Mrinalini Sinha has called, 'the rhetorical and ideological efficacy' of notions of masculinity 'in underwriting various arrangements of power'. The article's central argument is that the history of masculinity should move 'beyond masculinity' by analysing the deployment of masculinity in the making, legitimisation and contestation of not just power relations of gender, but also other power relations. It points to the origins of this framework in post-structuralist strands of women's and gender history and evaluates critically the usefulness of the notion of 'hegemonic masculinity' for such an approach.

The Qualification Experiences for Safety-critical Software of POSAFE-Q

Energy Technology Data Exchange (ETDEWEB)

Kim, Jang Yeol; Son, Kwang Seop; Cheon, Se Woo; Lee, Jang Soo; Kwon, Kee Choon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

Programmable Logic Controllers (PLC) have been applied to the Reactor Protection System (RPS) and the Engineered Safety Feature (ESF)-Component Control System (CCS) as the major safety system components of nuclear power plants. This paper describes experiences on the qualification of the safety-critical software including the pCOS kernel and system tasks related to a safety-grade PLC, i.e. the works done for the Software Verification and Validation, Software Safety Analysis, Software Quality Assurance, and Software Configuration Management etc.

Calibration of RB reactor power

International Nuclear Information System (INIS)

Sotic, O.; Markovic, H.; Ninkovic, M.; Strugar, P.; Dimitrijevic, Z.; Takac, S.; Stefanovic, D.; Kocic, A.; Vranic, S.

1976-09-01

The first and only calibration of RB reactor power was done in 1962, and the obtained calibration ratio was used irrespective of the lattice pitch and core configuration. Since the RB reactor is being prepared for operation at higher power levels it was indispensable to reexamine the calibration ratio, estimate its dependence on the lattice pitch, critical level of heavy water and thickness of the side reflector. It was necessary to verify the reliability of control and dosimetry instruments, and establish neutron and gamma dose dependence on reactor power. Two series of experiments were done in June 1976. First series was devoted to tests of control and dosimetry instrumentation and measurements of radiation in the RB reactor building dependent on reactor power. Second series covered measurement of thermal and epithermal neuron fluxes in the reactor core and calculation of reactor power. Four different reactor cores were chosen for these experiments. Reactor pitches were 8, 8√2, and 16 cm with 40, 52 and 82 fuel channels containing 2% enriched fuel. Obtained results and analysis of these results are presented in this document with conclusions related to reactor safe operation

A Critical Heat Generation for Safe Nuclear Fuels after a LOCA

Directory of Open Access Journals (Sweden)

Jae-Yong Kim

2014-01-01

Full Text Available This study applies a thermo-elasto-plastic-creep finite element procedure to the analysis of an accidental behavior of nuclear fuel as well as normal behavior. The result will be used as basic data for the robust design of nuclear power plant and fuels. We extended the range of mechanical strain from small or medium to large adopting the Hencky logarithmic strain measure in addition to the Green-Lagrange strain and Almansi strain measures, for the possible large strain situation in accidental environments. We found that there is a critical heat generation after LOCA without ECCS (event category 5, under which the cladding of fuel sustains the internal pressure and temperature for the time being for the rescue of the power plant. With the heat generation above the critical value caused by malfunctioning of the control rods, the stiffness of cladding becomes zero due to the softening by high temperature. The weak position of cladding along the length continuously bulges radially to burst and to discharge radioactive substances. This kind of cases should be avoid by any means.

The AAEC rotamak experiment description and preliminary results at low input power

International Nuclear Information System (INIS)

Durance, G.; Hogg, G.R.; Tendys, J.

1984-12-01

A description is given of the initial experiments on a rotamak device operating with 10 kW input power at a frequency of 1.85 MHz. The experimental apparatus and the diagnostic systems are also described. The matching of the radiofrequency power sources to the drive coils is discussed and details are given of the results from discharges in hydrogen, deuterium, helium and argon. The plasma/magnetic field configuration appears to be stable although, under certain conditions, fluctuations of the magnetic field structure have been observed

The development of nuclear power and emergency response

International Nuclear Information System (INIS)

Pan Ziqiang

2007-01-01

Nuclear power is a safe, clean energy, which has been evidenced by the history of nuclear power development. Nuclear power is associated with very low risk but not equal to zero. Accident emergency response and preparedness is a final barrier necessary to reduce potential risks that may arise from nuclear power plants, which must be enhanced. In the course of accident emergency response and preparedness, it is highly necessary to draw domestic and foreign experiences and lessons. Lastly, the paper presents the discussions of some issues which merit attention with respect to emergency response and preparedness in China. (authors)

High average power CW FELs [Free Electron Laser] for application to plasma heating: Designs and experiments

International Nuclear Information System (INIS)

Booske, J.H.; Granatstein, V.L.; Radack, D.J.; Antonsen, T.M. Jr.; Bidwell, S.; Carmel, Y.; Destler, W.W.; Latham, P.E.; Levush, B.; Mayergoyz, I.D.; Zhang, Z.X.

1989-01-01

A short period wiggler (period ∼ 1 cm), sheet beam FEL has been proposed as a low-cost source of high average power (1 MW) millimeter-wave radiation for plasma heating and space-based radar applications. Recent calculation and experiments have confirmed the feasibility of this concept in such critical areas as rf wall heating, intercepted beam (''body'') current, and high voltage (0.5 - 1 MV) sheet beam generation and propagation. Results of preliminary low-gain sheet beam FEL oscillator experiments using a field emission diode and pulse line accelerator have verified that lasing occurs at the predicted FEL frequency. Measured start oscillation currents also appear consistent with theoretical estimates. Finally, we consider the possibilities of using a short-period, superconducting planar wiggler for improved beam confinement, as well as access to the high gain, strong pump Compton regime with its potential for highly efficient FEL operation

When Sex and Power Collide: An Argument for Critical Sexuality Studies.

Science.gov (United States)

Fahs, Breanne; McClelland, Sara I

2016-01-01

Attentive to the collision of sex and power, we add momentum to the ongoing development of the subfield of critical sexuality studies. We argue that this body of work is defined by its critical orientation toward the study of sexuality, along with a clear allegiance to critical modalities of thought, particularly feminist thought. Critical sexuality studies takes its cues from several other critical moments in related fields, including critical psychology, critical race theory, critical public health, and critical youth studies. Across these varied critical stances is a shared investment in examining how power and privilege operate, understanding the role of historical and epistemological violence in research, and generating new models and paradigms to guide empirical and theoretical research. With this guiding framework, we propose three central characteristics of critical sexuality studies: (a) conceptual analysis, with particular attention to how we define key terms and conceptually organize our research (e.g., attraction, sexually active, consent, agency, embodiment, sexual subjectivity); (b) attention to the material qualities of abject bodies, particularly bodies that are ignored, overlooked, or pushed out of bounds (e.g., viscous bodies, fat bodies, bodies in pain); and (c) heteronormativity and heterosexual privilege, particularly how assumptions about heterosexuality and heteronormativity circulate in sexuality research. Through these three critical practices, we argue that critical sexuality studies showcases how sex and power collide and recognizes (and tries to subvert) the various power imbalances that are deployed and replicated in sex research.

Design of Hemispherical Downward-Facing Vessel for Critical Heat Flux Experiment

International Nuclear Information System (INIS)

Hwang, J. S.; Suh, K. Y.

2009-01-01

The in-vessel retention (IVR) is one of major severe accident management strategies adopted by some operating nuclear power plants during a severe accident. The recent Shin-Gori Units 3 and 4 of the Advanced Power Reactor 1400 MWe (APR1400) have adopted the external reactor vessel cooling (ERVC) by reactor cavity flooding as major severe accident management strategy. The ERVC in the APR1400 design resorts to active flooding system using thermal insulator. The Corium Attack Stopper Apparatus Spherical Channel (CASA SC) tests are conducted to measure the critical power and critical heat flux (CHF) on a downward hemispherical vessel scaled down from the APR1400 lower head by 1/10 on a linear scale. CASA is designed through scaling and thermal analysis to simulate the APR1400 vessel and thermal insulator. The heated vessel of CASA SC represents the external surface of a hemisphere submerged vessel in water. The heated vessel plays an important role in the ERVC experiment depending on the configuration of oxide pool and metallic layer. Hand calculation and computational analysis are performed to produce high heat flux from the downward facing hemisphere in excess of 1 MW/m 2

Wireless coexistence and interference test method for low-power wireless sensor networks

NARCIS (Netherlands)

Serra, R.; Nabi, Majid

2015-01-01

Wireless sensor networks (WSNs) are being increasingly introduced for critical applications such as safety, security and health. One the main characteristic requirements of such networks are that they should function with relative low power. Therefore the wireless links are more vulnerable.

The child and family experience of power mobility: a qualitative synthesis.

Science.gov (United States)

Livingstone, Roslyn; Field, Debra

2015-04-01

The aim of this study was to critically synthesize qualitative evidence regarding the child and family experience of power mobility, and to examine how this evidence fits with current theoretical concepts. Electronic database/hand searches were undertaken in September 2012 and updated in February 2014. The searches were restricted to qualitative studies published in English before February 2014 that included at least one child under the age of 19 with a disability and described an outcome related to the use of power mobility. Inclusion criteria were set a priori. Two reviewers independently screened titles, abstracts, and full-text articles and extracted data. McMaster qualitative review forms were used for quality appraisal. Of 259 titles, 21 met inclusion criteria. From 143 codes, 15 second-order themes were developed using constant comparison and analysis. Three overarching themes emerged: power mobility experience promotes developmental change and independent mobility; power mobility enhances social relationships and engagement in meaningful life experiences; and power mobility access and use is influenced by factors in the physical, social, and attitudinal environment. This qualitative research provides rich and rigorous evidence supporting the benefits of power mobility for children and families. Numerous factors, which warrant careful consideration, influence power mobility access and use. © 2014 Mac Keith Press.

Inherently safe reactors

International Nuclear Information System (INIS)

Maartensson, Anders

1992-01-01

A rethinking of nuclear reactor safety has created proposals for new designs based on inherent and passive safety principles. Diverging interpretations of these concepts can be found. This article reviews the key features of proposed advanced power reactors. An evaluation is made of the degree of inherent safety for four different designs: the AP-600, the PIUS, the MHTGR and the PRISM. The inherent hazards of today's most common reactor principles are used as reference for the evaluation. It is concluded that claims for the new designs being inherently, naturally or passively safe are not substantiated by experience. (author)

Simple Automatic File Exchange (SAFE) to Support Low-Cost Spacecraft Operation via the Internet

Science.gov (United States)

Baker, Paul; Repaci, Max; Sames, David

1998-01-01

Various issues associated with Simple Automatic File Exchange (SAFE) are presented in viewgraph form. Specific topics include: 1) Packet telemetry, Internet IP networks and cost reduction; 2) Basic functions and technical features of SAFE; 3) Project goals, including low-cost satellite transmission to data centers to be distributed via an Internet; 4) Operations with a replicated file protocol; 5) File exchange operation; 6) Ground stations as gateways; 7) Lessons learned from demonstrations and tests with SAFE; and 8) Feedback and future initiatives.

Operating experience feedback on lose of offsite power supply for nuclear power plant

International Nuclear Information System (INIS)

Jiao Feng; Hou Qinmai; Che Shuwei

2013-01-01

The function of the service power system of a nuclear power plant is to provide safe and reliable power supply for the nuclear power plant facilities. The safety of nuclear power plant power supply is essential for nuclear safety. The serious accident of Fukushima Daiichi nuclear power plant occurred due to loss of service power and the ultimate heat sink. The service power system has two independent offsite power supplies as working power and auxiliary power. This article collected events of loss of offsite power supply in operating nuclear power plants at home and abroad, and analyzed the plant status and cause of loss of offsite power supply events, and proposed improvement measures for dealing with loss of offsite power supply. (authors)

Technical criteria for the prevention of criticality

Energy Technology Data Exchange (ETDEWEB)

Tomlinson, R E

1971-04-15

Atlantic Richfield Hanford Company (ARHCO) Policy Guide 1.6.6, 'Criticality Prevention' and Operating Instruction 1.6.6.2, 'Criticality Prevention in Process Facilities', present the policy of the Chemical Processing Division with respect to the control of criticality hazards, and delegate the responsibility for specifying safe limits for the design and operation of process facilities to the Manager, Research and Development Department. The purpose of this document is to define the technical criteria to be used in developing the limits within which CPD facilities are to be designed and operated. These criteria are based on the operating experience accumulated from the processing of fissile materials since the year 1944. The mere existence of a fissile material in quantities greater than a minimum critical mass creates some finite risk that criticality will occur. This risk of criticality can be held to a very low value by imposing restrictions on the manner in which the fissile material is stored or handled. Such controls are to be imposed as needed.

Technical criteria for the prevention of criticality

International Nuclear Information System (INIS)

Tomlinson, R.E.

1971-01-01

Atlantic Richfield Hanford Company (ARHCO) Policy Guide 1.6.6, 'Criticality Prevention' and Operating Instruction 1.6.6.2, 'Criticality Prevention in Process Facilities', present the policy of the Chemical Processing Division with respect to the control of criticality hazards, and delegate the responsibility for specifying safe limits for the design and operation of process facilities to the Manager, Research and Development Department. The purpose of this document is to define the technical criteria to be used in developing the limits within which CPD facilities are to be designed and operated. These criteria are based on the operating experience accumulated from the processing of fissile materials since the year 1944. The mere existence of a fissile material in quantities greater than a minimum critical mass creates some finite risk that criticality will occur. This risk of criticality can be held to a very low value by imposing restrictions on the manner in which the fissile material is stored or handled. Such controls are to be imposed as needed

Human performance tools in nuclear power plants. Introduction, implementation and experiences

International Nuclear Information System (INIS)

Dexheimer, Kai; Bassing, Gerd; Kreuzer, Peter

2015-01-01

The basis of safe nuclear power plant operation (NPP) and a strong safety culture is the professional application of Human Performance Optimisation Tools (HPO). HPO trainings have been carried out by German NPPs for a number of years and recently also by Swiss NPPs. This article describes the origination, the bases, experiences and thereby the special features of the HPO training programme applied by German NPP operators. Moreover, this article provides an outlook on future developments - in particular when considering the requirements of the ongoing phase out of nuclear energy in Germany.

Learning From Critical Collective Spaces: Reflections on the Community-Diversity Dialectic in Safe Spaces

Directory of Open Access Journals (Sweden)

Jennifer Wallin-Ruschman

2016-05-01

Full Text Available Safe spaces have the potential to become prefigurative groups that aim to create social change. The idea of a safe space as a place separate and sheltered from dominant culture to mobilize for social change has gained traction in a number of academic and practical areas. However, safe spaces have the ability to be both progressive and regressive. To guide our discussion we utilize the concept of community-diversity dialectic to address the tension between these forces within two settings. First we discuss research in an upper level college course rooted in feminist praxis. Then we discuss a faith community’s use of adaptive liturgy with parishioners with intellectual disabilities. Following this discussion, we offer a new term, “critical collective spaces”, to better capture the work done in these spaces. We offer this alternative label to move popular and academic discourse away from debating about how “safe” these spaces are (or are not and toward a more nuanced discussion of the community-diversity dialectic and other tensions within these spaces. Our overall intention is to generate dialogue on the regressive and progressive aspects of these locations and to inform the activism and community building process within prefigurative politics more broadly.

Encoded low swing for ultra low power interconnect

NARCIS (Netherlands)

Krishnan, R.; Pineda de Gyvez, J.

2003-01-01

We present a novel encoded-low swing technique for ultra low power interconnect. Using this technique and an efficient circuit implementation, we achieve an average of 45.7% improvement in the power-delay product over the schemes utilizing low swing techniques alone, for random bit streams. Also, we

Low power laser in Odonto-stomathology

International Nuclear Information System (INIS)

Valiente Zaldivar, Carolina

2009-01-01

The use of low power laser technology in our country, and mainly in Odonto-stomathology, have gad a constant evolution and development since the 80's, being significant the social repercution between professionals and patients, achieving and alternative of treatment, which is non painful, and the results, either analgesic, anti-inflammatory, and stimulating of the tissue regeneration. This work intends to show the therapeutic procedure, and the different clinical entities, treated with Cuban instruments, that contains red or infrared diode lasers. The experience, during more than 20 years of the use of this kind of low power lasers, with different radiation techniques, includes: laser therapy or their combination with acupuncture points, so-called Laser puncture, which makes this technology an alternative of treatment for several clinical entities in correspondence with alterations of the tissues of the tooth, the mucose, neuronal alterations, and so on, procedures that are generalized in more that 60 services of our country. (Author)

Calculations on safe storage and transportation of radioactive materials

Energy Technology Data Exchange (ETDEWEB)

Hathout, A M; El-Messiry, A M; Amin, E [National Center for Nuclear Safety and Radiation Control and AEA, Cairo (Egypt)

1997-12-31

In this work the safe storage and transportation of fresh fuel as a radioactive material studied. Egypt planned ET RR 2 reactor which is of relatively high power and would require adequate handling and transportation. Therefore, the present work is initiated to develop a procedure for safe handling and transportation of radioactive materials. The possibility of reducing the magnitude of radiation transmitted on the exterior of the packages is investigated. Neutron absorbers are used to decrease the neutron flux. Criticality calculations are carried out to ensure the achievement of subcriticality so that the inherent safety can be verified. The discrete ordinate transport code ANISN was used. The results show good agreement with other techniques. 2 figs., 2 tabs.

Critical fields and growth rates of the Tayler instability as probed by a columnar gallium experiment

OpenAIRE

Ruediger, Guenther; Gellert, Marcus; Schultz, Manfred; Strassmeier, Klaus G.; Stefani, Frank; Gundrum, Thomas; Seilmayer, Martin; Gerbeth, Gunter

2012-01-01

Many astrophysical phenomena (such as the slow rotation of neutron stars or the rigid rotation of the solar core) can be explained by the action of the Tayler instability of toroidal magnetic fields in the radiative zones of stars. In order to place the theory of this instability on a safe fundament it has been realized in a laboratory experiment measuring the critical field strength, the growth rates as well as the shape of the supercritical modes. A strong electrical current flows through a...

An analysis of operational experience during low power and shutdown and a plan for addressing human reliability assessment issues

International Nuclear Information System (INIS)

Barriere, M.; Luckas, W.; Whitehead, D.; Ramey-Smith, A.

1994-06-01

Recent nuclear power plant events (e.g. Chernobyl, Diablo Canyon, and Vogtle) and US Nuclear Regulatory Commission (NRC) reports (e.g. NUREG-1449) have led to concerns regarding human reliability during low power and shutdown (LP ampersand S) conditions and limitations of human reliability analysis (HRA) methodologies in adequately representing the LP ampersand S environment. As a result of these concerns, the NRC initiated two parallel research projects to assess the influence of LP ampersand S conditions on human reliability through an analysis of operational experience at pressurized water reactors (PWRs) an boiling water reactors (BWRs). These research projects, performed by Brookhaven National Laboratory for PWRS, and Sandia National Laboratories for BWRs, identified unique aspects of human performance during LP ampersand S conditions and provided a program plan for research and development necessary to improve existing HRA methodologies. This report documents the results of the analysis of LP ampersand S operating experience and describes the improved HRA program plan

The nuclear criticality information system's project to archive unpublished critical experiment data

International Nuclear Information System (INIS)

Koponen, B.L.; Doherty, A.L.; Clayton, E.D.

1991-01-01

Critical experiment facilities produced a large amount of important data during the past forty-five years. However, much useful data remains unpublished. The unpublished material exists in the form of experimenters' logbooks, notes, photographs, material descriptions, etc. These data could be important for computer code validation, understanding the physics of criticality, facility design, or for setting process limits. In the past, criticality specialists have been able to obtain unpublished details by direct contact with the experimenters. The closure of facilities and the loss of personnel is likely to lead to the loss of the facility records unless an effort is made to ensure that the records are preserved. It has been recognized for some time that the unpublished records of critical experiment facilities comprise a valuable resource, thus the Nuclear Criticality Information System (NCIS) is working to ensure that the records are preserved and made available via NCIS. As a first step in the archiving project, we identified criteria to help judge which series of experiments should be considered for archiving. Data that are used for validating calculations or the basis for subcritical limits in standards, handbooks, and guides are of particular importance. In this paper we will discuss the criteria for archiving, the priority list of experiments for archiving, and progress in developing an NCIS image database using current CD-ROM technology. (Author)

Research on laser detonation pulse circuit with low-power based on super capacitor

Science.gov (United States)

Wang, Hao-yu; Hong, Jin; He, Aifeng; Jing, Bo; Cao, Chun-qiang; Ma, Yue; Chu, En-yi; Hu, Ya-dong

2018-03-01

According to the demand of laser initiating device miniaturization and low power consumption of weapon system, research on the low power pulse laser detonation circuit with super capacitor. Established a dynamic model of laser output based on super capacitance storage capacity, discharge voltage and programmable output pulse width. The output performance of the super capacitor under different energy storage capacity and discharge voltage is obtained by simulation. The experimental test system was set up, and the laser diode of low power pulsed laser detonation circuit was tested and the laser output waveform of laser diode in different energy storage capacity and discharge voltage was collected. Experiments show that low power pulse laser detonation based on super capacitor energy storage circuit discharge with high efficiency, good transient performance, for a low power consumption requirement, for laser detonation system and low power consumption and provide reference light miniaturization of engineering practice.

Skin-safe photothermal therapy enabled by responsive release of acid-activated membrane-disruptive polymer from polydopamine nanoparticle upon very low laser irradiation.

Science.gov (United States)

Zhu, Rui; Gao, Feng; Piao, Ji-Gang; Yang, Lihua

2017-07-25

How to ablate tumor without damaging skin is a challenge for photothermal therapy. We, herein, report skin-safe photothermal cancer therapy provided by the responsive release of acid-activated hemolytic polymer (aHLP) from the photothermal polydopamine (PDA) nanoparticle upon irradiation at very low dosage. Upon skin-permissible irradiation (via an 850 nm laser irradiation at the power density of 0.4 W cm -2 ), the nanoparticle aHLP-PDA generates sufficient localized-heat to bring about mild hyperthermia treatment and consequently, responsively sheds off the aHLP polymer from its PDA nanocore; this leads to selective cytotoxicity to cancer cells under the acidic conditions of the extracellular microenvironment of tumor. As a result, our aHLP-PDA nanoparticle upon irradiation at a low dosage effectively inhibits tumor growth without damaging skin, as demonstrated using animal models. Effective in mitigating the otherwise inevitable skin damage in tumor photothermal therapy, the nanosystem reported herein offers an efficient pathway towards skin-safe photothermal therapy.

Coupling between particle and heat transport during power modulation experiments in Tore Supra

International Nuclear Information System (INIS)

Zou, X.L.; Giruzzi, G.; Artaud, J.F.; Bouquey, F.; Bremond, S.; Clary, J.; Darbos, C.; Eury, S.P.; Lennholm, M.; Magne, R.; Segui, J.L.

2004-01-01

Power modulations are a powerful tool often used to investigate heat transport processes in tokamaks. In some situations, this could also be an interesting method for the investigation of the particle transport due to the anomalous pinch. Low frequency (∼ 1 Hz) power modulation experiments, using both electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH), have been performed in the Tore Supra tokamak. Strong coupling has been observed between the temperature and density modulations during the low frequency ECRH and ICRH modulation experiments. It has been shown that mechanisms as outgassing, Ware pinch effect, curvature driven pinch are not likely to be responsible for this density modulation. Because of its dependence on temperature or temperature gradient, the thermodiffusion is a serious candidate to be the driving source for this density modulation. This analysis shows that low frequency power modulation experiments have a great potential for the investigation of the anomalous particle pinch in tokamaks. Future plans will include the use of more precise density profile measurements using X-mode reflectometry

Coupling between particle and heat transport during power modulation experiments in Tore Supra

Energy Technology Data Exchange (ETDEWEB)

Zou, X.L.; Giruzzi, G.; Artaud, J.F.; Bouquey, F.; Bremond, S.; Clary, J.; Darbos, C.; Eury, S.P.; Lennholm, M.; Magne, R.; Segui, J.L

2004-07-01

Power modulations are a powerful tool often used to investigate heat transport processes in tokamaks. In some situations, this could also be an interesting method for the investigation of the particle transport due to the anomalous pinch. Low frequency ({approx} 1 Hz) power modulation experiments, using both electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH), have been performed in the Tore Supra tokamak. Strong coupling has been observed between the temperature and density modulations during the low frequency ECRH and ICRH modulation experiments. It has been shown that mechanisms as outgassing, Ware pinch effect, curvature driven pinch are not likely to be responsible for this density modulation. Because of its dependence on temperature or temperature gradient, the thermodiffusion is a serious candidate to be the driving source for this density modulation. This analysis shows that low frequency power modulation experiments have a great potential for the investigation of the anomalous particle pinch in tokamaks. Future plans will include the use of more precise density profile measurements using X-mode reflectometry.

Sensitivity analysis of critical experiments with evaluated nuclear data libraries

International Nuclear Information System (INIS)

Fujiwara, D.; Kosaka, S.

2008-01-01

Criticality benchmark testing was performed with evaluated nuclear data libraries for thermal, low-enriched uranium fuel rod applications. C/E values for k eff were calculated with the continuous-energy Monte Carlo code MVP2 and its libraries generated from Endf/B-VI.8, Endf/B-VII.0, JENDL-3.3 and JEFF-3.1. Subsequently, the observed k eff discrepancies between libraries were decomposed to specify the source of difference in the nuclear data libraries using sensitivity analysis technique. The obtained sensitivity profiles are also utilized to estimate the adequacy of cold critical experiments to the boiling water reactor under hot operating condition. (authors)

Harnessing hospital purchase power to design safe care delivery.

Science.gov (United States)

Ebben, Steven F; Gieras, Izabella A; Gosbee, Laura Lin

2008-01-01

Since the Institute of Medicine's well-publicized 1999 report To Err is Human, the healthcare patient safety movement has grown at an exponential pace. However, much more can be done to advance patient safety from a care process design vantage point-improving safety through effective care processes and technology integration. While progress is being made, the chasm between technology developers and caregivers remains a profound void. Why hasn't more been done to expand our view of patient safety to include technology design? Healthcare organizations have not consolidated their purchasing power to expect improved designs. This article will (1) provide an assessment of the present state of healthcare technology management and (2) provide recommendations for collaborative design of safe healthcare delivery systems.

Low-Power Wireless Sensor Network Infrastructures

DEFF Research Database (Denmark)

Hansen, Morten Tranberg

Advancements in wireless communication and electronics improving form factor and hardware capabilities has expanded the applicability of wireless sensor networks. Despite these advancements, devices are still limited in terms of energy which creates the need for duty-cycling and low-power protocols...... peripherals need to by duty-cycled and the low-power wireless radios are severely influenced by the environmental effects causing bursty and unreliable wireless channels. This dissertation presents a communication stack providing services for low-power communication, secure communication, data collection......, and network management which enables construction of low-power wireless sensor network applications. More specifically, these services are designed with the extreme low-power scenarios of the SensoByg project in mind and are implemented as follows. First, low-power communication is implemented with Auto...

Power requirements for superior H-mode confinement on Alcator C-Mod: experiments in support of ITER

International Nuclear Information System (INIS)

Hughes, J.W.; Reinke, M.L.; Terry, J.L.; Brunner, D.; Greenwald, M.; Hubbard, A.E.; LaBombard, B.; Lipschultz, B.; Ma, Y.; Wolfe, S.; Wukitch, S.J.; Loarte, A.

2011-01-01

Power requirements for maintaining sufficiently high confinement (i.e. normalized energy confinement time H 98 ≥ 1) in H-mode and its relation to H-mode threshold power scaling, P th , are of critical importance to ITER. In order to better characterize these power requirements, recent experiments on the Alcator C-Mod tokamak have investigated H-mode properties, including the edge pedestal and global confinement, over a range of input powers near and above P th . In addition, we have examined the compatibility of impurity seeding with high performance operation, and the influence of plasma radiation and its spatial distribution on performance. Experiments were performed at 5.4 T at ITER relevant densities, utilizing bulk metal plasma facing surfaces and an ion cyclotron range of frequency waves for auxiliary heating. Input power was scanned both in stationary enhanced D α (EDA) H-modes with no large edge localized modes (ELMs) and in ELMy H-modes in order to relate the resulting pedestal and confinement to the amount of power flowing into the scrape-off layer, P net , and also to the divertor targets. In both EDA and ELMy H-mode, energy confinement is generally good, with H 98 near unity. As P net is reduced to levels approaching that in L-mode, pedestal temperature diminishes significantly and normalized confinement time drops. By seeding with low-Z impurities, such as Ne and N 2 , high total radiated power fractions are possible, along with substantial reductions in divertor heat flux (>4x), all while maintaining H 98 ∼ 1. When the power radiated from the confined versus unconfined plasma is examined, pedestal and confinement properties are clearly seen to be an increasing function of P net , helping to unify the results with those from unseeded H-modes. This provides increased confidence that the power flow across the separatrix is the correct physics basis for ITER extrapolation. The experiments show that P net /P th of one or greater is likely to lead to H

Evaluation of power history during power burst experiments in TRACY by combination of gamma-ray and thermal neutron detectors

International Nuclear Information System (INIS)

Yanagisawa, Hiroshi; Ohno, Akio

2002-01-01

A combination method using γ-ray and thermal neutron detectors was newly applied to the accurate evaluation of power histories during reactivity-initiated power burst experiments in the Transient Experiment Critical Facility (TRACY). During an initial power burst, the power history was determined using a fast response γ-ray ionization chamber, which was used because of its ability to exactly trace the power history within a short duration of the initial burst. After the initial burst, a micro fission chamber containing highly enriched uranium was used for the determination of the power history because the γ-ray ionization chamber could not be applied due to the contribution of delayed γ-rays from fission products. By the present method, the power histories were evaluated for the experiments in the range of 1.50 to 2.93$ of the reactivity insertion. It was found that the peak power and integrated power as determined by the previous method using only the micro fission chamber were underestimated to be 40% and 30% in maximum, respectively, in comparison with the results from the present evaluation. The numerical simulation performed by using the Monte Carlo method indicated that the underestimation could be comprehended by considering the time delay of thermal neutron detection of the fission chamber, which arose from the flight-time of neutrons from the TRACY core to the fission chamber. (author)

Health physics experiences in achieving ALARA exposures to plant personnel at NAPS

International Nuclear Information System (INIS)

Ramakrishna, V.; Lal Chand

2000-01-01

Unit 1 of NAPS achieved first criticality on 12.3.1989 and Unit 2 achieved on 24.10.1991. Till the end of Feb-2000 these units have completed 1890 and 1811 full power days respectively. The performance of NAPS was expected to be better than the earlier Indian reactors in respect of safe production as well as cumulative radiation exposures. This is because of the major design improvements like: fully double containment system, elimination of 41 Ar by introducing light water in calandria vault, reduction of core based fuel failure rate, separation of high radiation equipment to no occupancy areas during normal operation, a separate purification building for the purification of both moderator and PHT systems, a better layout of equipment and plant areas, elimination of unnecessary equipment in various systems besides ensuring the reliability of equipment for safe operation, selection of materials with low corrosion and activation characteristics etc. In this paper, the operational health physics experiences at NAPS to achieve ALARA exposures to plant personnel are described briefly. (author)

Design status and future research programme for a sub-critical assembly driven by a proton accelerator with proton energy 660 MeV for experiments on long-lived fission products and minor actinides transmutation (Sad)

International Nuclear Information System (INIS)

Gustov, S.A.; Mirokhin, I.V.; Morozov, N.A.; Onischenko, L.M.; Savchenko, O.V.; Sissakian, A.N.; Shvetsov, V.N.; Tretyakov, I.T.; Lopatkin, A.V.; Vorontsov, M.T.

2003-01-01

Report presents project for the construction of a low power integral system on the basis of the proton accelerator of energy 660 MeV and sub-critical MOX blanket with uranium-plutonium fuel. Installation includes sub-critical core with a nominal thermal power of 15-20 kW. Multiplication coefficient k eff = 0,95 and the accelerator beam power of 0.75-1 kW. The experimental programme for SAD will be focused on solving different aspects of reactor physics, reaction rates measurements and benchmarking. The first conceptual design of the SAD experiment is completed in the form of the ISTC Project Proposal 2267. Realisation of the SAD facility may be expected in about 3-4 years. (author)

Design study of a low-power, low-noise front-end for multianode silicon drift detectors

International Nuclear Information System (INIS)

Caponetto, L.; Presti, D. Lo; Randazzo, N.; Russo, G.V.; Leonora, E.; Lo Nigro, L.; Petta, C.; Reito, S.; Sipala, V.

2005-01-01

The read-out for Silicon Drift Detectors in the form of a VLSI chip is presented, with a view to applications in High Energy Physics and space experiments. It is characterised by extremely low power dissipation, small noise and size

ICSBEP-2007, International Criticality Safety Benchmark Experiment Handbook

International Nuclear Information System (INIS)

Blair Briggs, J.

2007-01-01

1 - Description: The Critically Safety Benchmark Evaluation Project (CSBEP) was initiated in October of 1992 by the United Sates Department of Energy. The project quickly became an international effort as scientist from other interested countries became involved. The International Criticality Safety Benchmark Evaluation Project (ICSBEP) is now an official activity of the Organization of Economic Cooperation and Development - Nuclear Energy Agency (OECD-NEA). This handbook contains criticality safety benchmark specifications that have been derived from experiments that were performed at various nuclear critical facilities around the world. The benchmark specifications are intended for use by criticality safety engineers to validate calculational techniques used to establish minimum subcritical margins for operations with fissile material. The example calculations presented do not constitute a validation of the codes or cross section data. The work of the ICSBEP is documented as an International Handbook of Evaluated Criticality Safety Benchmark Experiments. Currently, the handbook spans over 42,000 pages and contains 464 evaluations representing 4,092 critical, near-critical, or subcritical configurations and 21 criticality alarm placement/shielding configurations with multiple dose points for each and 46 configurations that have been categorized as fundamental physics measurements that are relevant to criticality safety applications. The handbook is intended for use by criticality safety analysts to perform necessary validations of their calculational techniques and is expected to be a valuable tool for decades to come. The ICSBEP Handbook is available on DVD. You may request a DVD by completing the DVD Request Form on the internet. Access to the Handbook on the Internet requires a password. You may request a password by completing the Password Request Form. The Web address is: http://icsbep.inel.gov/handbook.shtml 2 - Method of solution: Experiments that are found

Criticality experiment for No.2 core of DF-VI fast neutron criticality facility

International Nuclear Information System (INIS)

Yang Lijun; Liu Zhenhua; Yan Fengwen; Luo Zhiwen; Chu Chun; Liang Shuhong

2007-01-01

At the completion of the DF-VI fast neutron criticality facility, its core changed, and it was restarted and a series of experiments and measurements were made. According to the data from 29 criticality experiments, the criticality element number and mass were calculated, the control rod reactivity worth were measured by period method and rod compensate method, reactivity worth of safety rod and safety block were measured using reactivity instrument; the reactivity worth of outer elements and radial distribution of elements were measured too. Based on all the measurements mentioned above, safety operation parameters for core 2 in DF-VI fast neutron criticality facility were conformed. (authors)

The impact and applicability of critical experiment evaluations

Energy Technology Data Exchange (ETDEWEB)

Brewer, R. [Los Alamos National Lab., NM (United States)

1997-06-01

This paper very briefly describes a project to evaluate previously performed critical experiments. The evaluation is intended for use by criticality safety engineers to verify calculations, and may also be used to identify data which need further investigation. The evaluation process is briefly outlined; the accepted benchmark critical experiments will be used as a standard for verification and validation. The end result of the project will be a comprehensive reference document.

Long Term Analysis of Adaptive Low-Power Instrument Platform Power and Battery Performance

Science.gov (United States)

Edwards, T.; Bowman, J. R.; Clauer, C. R.

2017-12-01

Operation of the Autonomous Adaptive Low-Power Instrument Platform (AAL-PIP) by the Magnetosphere-Ionosphere Science Team (MIST) at Virginia Tech has been ongoing for about 10 years. These instrument platforms are deployed on the East Antarctic Plateau in remote locations that are difficult to access regularly. The systems have been designed to operate unattended for at least 5 years. During the Austral summer, the systems charge batteries using solar panels and power is provided by the batteries during the winter months. If the voltage goes below a critical level, the systems go into hibernation and wait for voltage from the solar panels to initiate a restart sequence to begin operation and battery charging. Our first system was deployed on the East Antarctic Plateau in 2008 and we report here on an analysis of the power and battery performance over multiple years and provide an estimate for how long these systems can operate before major battery maintenance must be performed.

The operating staff of nuclear power plants

International Nuclear Information System (INIS)

Schlegel, G.; Christ, W.

1988-01-01

The training of its staff is one of the pillars of the safe and economical operation of a power plant. This is why power plant owners began to systematically train their staff already in the 50s, and why they created central training facilities. Staff members who have undergone this training make an indispensable contribution to the acceptedly high safety and availability of German power plants. The substantial cost of creating training facilities and of schooling plant staff is considered to be an investment for the future. Low labour turnover permits careful observation and development of staff and leads to a high standard of knowledge and experience. (orig./HSCH) [de

Inherently safe technologies-chemical and nuclear

International Nuclear Information System (INIS)

Weinberg, A.M.

1984-01-01

Probabilistic risk assessments show an inverse relationship between the likelihood and the consequences of nuclear and chemical plant accidents, but the Bhopal accident has change public complacency about the safety of chemical plants to such an extent that public confidence is now at the same low level as with nuclear plants. The nuclear industry's response was to strengthen its institutions and improve its technologies, but the public may not be convinced. One solution is to develop reactors which do not depend upon the active intervention of humans of electromechanical devices to deal with emergencies, but which have physical properties that limit the possible temperature and power of a reactor. The Process Inherent Ultimately Safe and the modular High-Temperature Gas-Cooled reactors are two possibilities. the chemical industry needs to develop its own inherently safe design precepts that incorporate smallness, safe processes, and hardening against sabotage. 5 references

International dosimetry experiment on the zero power pile of the Boris Kidric Institute at Vinca (Yugoslavia) (1961)

International Nuclear Information System (INIS)

Weill, J.; Furet, J.; Baillet, J.; Donvez, G.; Duchene, J.; Gras, R.; Mercier, R.; Chenouard, J.; Lecomte, J.

1961-01-01

On the occasion of the international dosimetry experiment on the zero power pile of the Yugoslavian Atomic Energy Centre at Vinca, the Commissariat a l'energie Atomique had agreed to prepare the measurement and security equipment and see to the manipulation of the heavy water, and in addition was responsible for the operation and the starting up of the pile during the experiment. The measurement and security apparatus, developed at Saclay and installed on the pile for low and high pressure runs, is listed, together with the safety equipment added near the control room. The various operations and manipulations carried out on the pile are described: filling with heavy water, starting up, determination of the critical level, testing the efficiency of the rods, operating the pile during the experiments. By operating to a carefully planned schedule, the experiments were, finished before the date fixed by the International Atomic Agency. (authors) [fr

Program of nuclear criticality safety experiment at JAERI

International Nuclear Information System (INIS)

Kobayashi, Iwao; Tachimori, Shoichi; Takeshita, Isao; Suzaki, Takenori; Ohnishi, Nobuaki

1983-11-01

JAERI is promoting the nuclear criticality safety research program, in which a new facility for criticality safety experiments (Criticality Safety Experimental Facility : CSEF) is to be built for the experiments with solution fuel. One of the experimental researches is to measure, collect and evaluate the experimental data needed for evaluation of criticality safety of the nuclear fuel cycle facilities. Another research area is a study of the phenomena themselves which are incidental to postulated critical accidents. Investigation of the scale and characteristics of the influences caused by the accident is also included in this research. The result of the conceptual design of CSEF is summarized in this report. (author)

Plant operational states analysis in low power and shutdown PSA

International Nuclear Information System (INIS)

He Jiandong; Qiu Yongping; Zhang Qinfang; An Hongzhen; Li Maolin

2013-01-01

The purpose of Plant Operational States (POS) analysis is to disperse the continuous and dynamic process of low power and shutdown operation, which is the basis of developing event tree models for accident sequence analysis. According to the design of a 300 MW Nuclear Power Plant Project, operating experience and procedures of the reference plant, a detailed POS analysis is carried out based on relative criteria. Then, several kinds of POS are obtained, and the duration of each POS is calculated according to the operation records of the reference plant. The POS analysis is an important element in low power and shutdown PSA. The methodology and contents provide reference for POS analysis. (authors)

Critical mass experiment using U-235 foils and lucite plates

International Nuclear Information System (INIS)

Sanchez, R.; Butterfield, K.; Kimpland, R.; Jaegers, P.

1998-01-01

The main objective of this experiment was to show how the multiplication of the system increases as moderated material is placed between highly enriched uranium foils. In addition, this experiment served to demonstrate the hand-stacking techniques, and approach to criticality by remote operation. This experiment was designed by Tom McLaughlin in the mid seventies as part of the criticality safety course that is taught at Los Alamos Critical Experiment Facility (LACEF). The W-U-235 ratio for this experiment was 215 which is where the minimum critical mass for this configuration occurs

Critical mass experiment using 235U foils and lucite plates

International Nuclear Information System (INIS)

Sanchez, R.; Butterfield, K.; Kimpland, R.; Jaegers, P.

1998-01-01

This experiment demonstrated how the neutron multiplication of a system increases as moderated material is placed between highly enriched uranium foils. In addition, this experiment served to demonstrate the hand-stacking technique and approach to criticality be remote operation. This experiment was designed by McLaughlin in the mid-seventies as part of the criticality safety course that is taught at the Los Alamos Critical Experiments Facility. The H/ 235 U ratio for this experiment was 215, which is the ratio at which the minimum critical mass for this configuration occurs

Safe Spaces, Support, Social Capital: A Critical Analysis of Artists Working with Vulnerable Young People in Educational Contexts

Science.gov (United States)

Sellman, Edward

2015-01-01

This article provides a critical and thematic analysis of three research projects involving artists working with vulnerable young people in educational contexts. It argues that artists create safe spaces in contrast to traditional educational activities but it will also raise questions about what constitutes such a space for participants. It will…

Choosing and Using Safe Water Technologies: Evidence from a Field Experiment in Kenya

OpenAIRE

Luoto, Jill Emily

2010-01-01

This dissertation examines the decision-making of poor rural Kenyan households with respect to the adoption of point-of-use (POU) safe water technologies designed to expand access to safe drinking water in the developing world. Low-cost POU products such as chlorine and filters substantially reduce diarrhea, which kills two million children in poor countries each year. Nevertheless, POU products remain little used in many parts of the developing world, even when they are widely available at s...

Light water ultra-safe plant concept: First annual report

International Nuclear Information System (INIS)

Klevans, E.

1987-01-01

Since the accident at Three Mile Island (TMI) Penn State Nuclear Engineering Department Faculty and Staff have considered various methods to improve already safe reactor designs and public perception of the safety of Nuclear Power. During the last year, the Department of Energy funded the study of a plant reconfiguration originally proposed by M.A. Shultz. This report presents the status of the project at the end of the first year. A broad set of specifications to improve safety and public perception were set forth and the realization of these goals is achieved in a plant design named, ''The Light Water Ultra-Safe Plant Concept.'' The most significant goals of the concept address the station black-out problem and simplification of required operator actions during abnormal situations. These goals are achieved in the Ultra-Safe Concept by addition of an in-containment atmospheric tank containing a large quantity of cool water, replacement of the conventional PWR pressurizer system with a pressurizing pump, internal emergency power generation, and arrangement of components to utilize natural circulation at shut-down. The first year effort included an evaluation of the normal operation characteristics of the primary system pressurizing concept, evaluating parameters and modeling for analysis of the shutdown scenario, design of a low power density core, design of a low-pressure waste handling system, arrangement of a drainage system for pipe break considerations, and failure modes and effects analysis

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)

Critical experiments on an enriched uranium solution system containing periodically distributed strong thermal neutron absorbers

International Nuclear Information System (INIS)

Rothe, R.E.

1996-01-01

A series of 62 critical and critical approach experiments were performed to evaluate a possible novel means of storing large volumes of fissile solution in a critically safe configuration. This study is intended to increase safety and economy through use of such a system in commercial plants which handle fissionable materials in liquid form. The fissile solution's concentration may equal or slightly exceed the minimum-critical-volume concentration; and experiments were performed for high-enriched uranium solution. Results should be generally applicable in a wide variety of plant situations. The method is called the 'Poisoned Tube Tank' because strong neutron absorbers (neutron poisons) are placed inside periodically spaced stainless steel tubes which separate absorber material from solution, keeping the former free of contamination. Eight absorbers are investigated. Both square and triangular pitched lattice patterns are studied. Ancillary topics which closely model typical plant situations are also reported. They include the effect of removing small bundles of absorbers as might occur during inspections in a production plant. Not taking the tank out of service for these inspections would be an economic advantage. Another ancillary topic studies the effect of the presence of a significant volume of unpoisoned solution close to the Poisoned Tube Tank on the critical height. A summary of the experimental findings is that boron compounds were excellent absorbers, as expected. This was true for granular materials such as Gerstley Borate and Borax; but it was also true for the flexible solid composed of boron carbide and rubber, even though only thin sheets were used. Experiments with small bundles of absorbers intentionally removed reveal that quite reasonable tanks could be constructed that would allow a few tubes at a time to be removed from the tank for inspection without removing the tank from production service

SUNRAYCE 1993: Working safely with lead-acid batteries and photovoltaic power systems

Science.gov (United States)

Dephillips, M. P.; Moskowitz, P. D.; Fthenakis, V. M.

1992-11-01

The US Department of Energy (DOE) is sponsoring SUNRAYCE 93 to advance tile technology and use of photovoltaics and electric vehicles. Participants will use cars powered by photovoltaic modules and lead-acid storage batteries. This brochure, prepared for students and faculty participating in this race, outlines the health hazards presented by these electrical systems and gives guidance on strategies for their safe usage. At the outset, it should be noted that working with photovoltaic systems and batteries requires electric vehicle drivers and technicians to have 'hands-on' contact with the car on a daily basis. It is important that no one work near a photovoltaic energy system or battery, either in a vehicle or on the bench, unless they familiarize themselves with the components in use and know and observe safe work practices including the safety precautions described in the manuals provided by the various equipment vendors and this document.

Critical experiments simulating accidental water immersion of highly enriched uranium dioxide fuel elements

International Nuclear Information System (INIS)

Ponomarev-Stepnoi, N.N.; Glushkov, L.S.

2003-01-01

The paper focuses on experimental analysis of nuclear criticality safety at accidental water immersion of fuel elements of the Russian TOPAZ-2 space nuclear power system reactor. The structure of water-moderated heterogeneous critical assemblies at the NARCISS facility is described in detail, including sizes, compositions, densities of materials of the main assembly components for various core configurations. Critical parameters of the assemblies measured for varying number of fuel elements, height of fuel material in fuel elements and their arrangement in the water moderator with a uniform or variable spacing are presented. It has been found from the experiments that at accidental water immersion of fuel elements involved, the minimum critical mass equal to approximately 20 kg of uranium dioxide is achieved at 31-37 fuel elements. The paper gives an example of a physical model of the water-moderated heterogeneous critical assembly with a detailed characterization of its main components that can be used for calculations using different neutronic codes, including Monte Carlo ones. (author)

International handbook of evaluated criticality safety benchmark experiments

International Nuclear Information System (INIS)

2010-01-01

The Criticality Safety Benchmark Evaluation Project (CSBEP) was initiated in October of 1992 by the United States Department of Energy. The project quickly became an international effort as scientists from other interested countries became involved. The International Criticality Safety Benchmark Evaluation Project (ICSBEP) became an official activity of the Organization for Economic Cooperation and Development - Nuclear Energy Agency (OECD-NEA) in 1995. This handbook contains criticality safety benchmark specifications that have been derived from experiments performed at various nuclear critical facilities around the world. The benchmark specifications are intended for use by criticality safety engineers to validate calculational techniques used to establish minimum subcritical margins for operations with fissile material and to determine criticality alarm requirement and placement. Many of the specifications are also useful for nuclear data testing. Example calculations are presented; however, these calculations do not constitute a validation of the codes or cross section data. The evaluated criticality safety benchmark data are given in nine volumes. These volumes span over 55,000 pages and contain 516 evaluations with benchmark specifications for 4,405 critical, near critical, or subcritical configurations, 24 criticality alarm placement / shielding configurations with multiple dose points for each, and 200 configurations that have been categorized as fundamental physics measurements that are relevant to criticality safety applications. Experiments that are found unacceptable for use as criticality safety benchmark experiments are discussed in these evaluations; however, benchmark specifications are not derived for such experiments (in some cases models are provided in an appendix). Approximately 770 experimental configurations are categorized as unacceptable for use as criticality safety benchmark experiments. Additional evaluations are in progress and will be

NCIS - a Nuclear Criticality Information System (overview)

International Nuclear Information System (INIS)

Koponen, B.L.; Hampel, V.E.

1983-07-01

A Nuclear Criticality Information System (NCIS) is being established at the Lawrence Livermore National Laboratory (LLNL) in order to serve personnel responsible for safe storage, transport, and handling of fissile materials and those concerned with the evaluation and analysis of nuclear, critical experiments. Public concern for nuclear safety provides the incentive for improved access to nuclear safety information

The origin of power-law distributions in self-organized criticality

International Nuclear Information System (INIS)

Yang, C B

2004-01-01

The origin of power-law distributions in self-organized criticality is investigated by treating the variation of the number of active sites in the system as a stochastic process. An avalanche is then regarded as a first-return random-walk process in a one-dimensional lattice. Power-law distributions of the lifetime and spatial size are found when the random walk is unbiased with equal probability to move in opposite directions. This shows that power-law distributions in self-organized criticality may be caused by the balance of competitive interactions. At the mean time, the mean spatial size for avalanches with the same lifetime is found to increase in a power law with the lifetime. (letter to the editor)

Low Power Consumption Wireless Sensor Communication System Integrated with an Energy Harvesting Power Source

Directory of Open Access Journals (Sweden)

Vlad MARSIC

2013-01-01

Full Text Available This paper presents the testing results of a wireless sensor communication system with low power consumption integrated with an energy harvesting power source. The experiments focus on the system’s capability to perform continuous monitoring and to wirelessly transmit the data acquired from the sensors to a user base station, for realization of completely battery-free wireless sensor system. Energy harvesting technologies together with system design optimization for power consumption minimization ensure the system’s energy autonomous capability demonstrated in this paper by presenting the promising testing results achieved following its integration with structural health monitoring and body area network applications.

Benchmark criticality experiments for fast fission configuration with high enriched nuclear fuel

International Nuclear Information System (INIS)

Sikorin, S.N.; Mandzik, S.G.; Polazau, S.A.; Hryharovich, T.K.; Damarad, Y.V.; Palahina, Y.A.

2014-01-01

Benchmark criticality experiments of fast heterogeneous configuration with high enriched uranium (HEU) nuclear fuel were performed using the 'Giacint' critical assembly of the Joint Institute for Power and Nuclear Research - Sosny (JIPNR-Sosny) of the National Academy of Sciences of Belarus. The critical assembly core comprised fuel assemblies without a casing for the 34.8 mm wrench. Fuel assemblies contain 19 fuel rods of two types. The first type is metal uranium fuel rods with 90% enrichment by U-235; the second one is dioxide uranium fuel rods with 36% enrichment by U-235. The total fuel rods length is 620 mm, and the active fuel length is 500 mm. The outer fuel rods diameter is 7 mm, the wall is 0.2 mm thick, and the fuel material diameter is 6.4 mm. The clad material is stainless steel. The side radial reflector: the inner layer of beryllium, and the outer layer of stainless steel. The top and bottom axial reflectors are of stainless steel. The analysis of the experimental results obtained from these benchmark experiments by developing detailed calculation models and performing simulations for the different experiments is presented. The sensitivity of the obtained results for the material specifications and the modeling details were examined. The analyses used the MCNP and MCU computer programs. This paper presents the experimental and analytical results. (authors)

Low-cost space fission power systems utilizing US and former Soviet Union experience and technology

International Nuclear Information System (INIS)

Wetch, J.R.; Britt, E.J.; Koester, J.K.; Gunther, N.; Ponomarev-Stepnoi, N.N.; Nikolaev, Y.V.; Nikitin, V.

1997-01-01

This report summarizes the author close-quote s approach to space power total economics. In the past 40 years of U.S. government sponsored space nuclear power developments, total economics has received only token consideration. In the real world, nuclear power has had limited acceptance where it provided the enabling capability i.e. isotopes for low power, long life, deep space missions, or reactor power for underwater nuclear submarines. It was also accepted where it was perceived to be more economic. Examples are nuclear reactor powered aircraft carriers, escort vessels and central station power stations. In any case, real and perceived public and environmental safety must always be included into the economic equation. copyright 1997 American Institute of Physics

Fire protection of safe shutdown capability at commercial nuclear power plants

International Nuclear Information System (INIS)

Sullivan, K.

1993-01-01

The comprehensive industrial safety standards and codes that exist today have evolved from lessons learned through past experience, research results, and improvements in technological capabilities. The current requirements for fire safety features of commercial nuclear power stations operated in the US are a notable example of this practice. Although fire protection has always been an important design requirement, from the aftermath of a serious fire that occurred in 1975 at the Browns Ferry plant, it was learned that the life safety and property protection concerns of the major fire insurance underwriters may not sufficiently encompass nuclear safety issues, particularly with regard to the potential for fire damage to result in the common mode failure of redundant trains of systems, and components important to the safe shutdown of the reactor. Following its investigations into the Browns Ferry fire, the Nuclear Regulatory Commission (NRC) promulgated guidance documents, which ultimately developed into mandatory regulations, necessary to assure the implementation of a fire protection program that would address nuclear safety concerns. The new criteria that evolved, contain prescriptive design features, as well as personnel and administrative requirements the Commission determined to be necessary to provide a defense-in-depth level of protection against the hazards of fire and its associated effects on safety related equipment. These criteria are primarily contained in Appendix R of Title 10 to the Code of Federal Regulations (10 CFR 50). Since 1983, various members of the Department of Nuclear Energy (DNE) at Brookhaven National Laboratory (BNL) have provided technical assistance to the Nuclear Regulatory Commission (NRC) in support of its evaluations of fire protection features implemented at commercial nuclear power stations operated in the US. This paper presents a discussion of the insights gained by the author during his active participation in this area

Review of studies on criticality safety evaluation and criticality experiment methods

International Nuclear Information System (INIS)

Naito, Yoshitaka; Yamamoto, Toshihiro; Misawa, Tsuyoshi; Yamane, Yuichi

2013-01-01

Since the early 1960s, many studies on criticality safety evaluation have been conducted in Japan. Computer code systems were developed initially by employing finite difference methods, and more recently by using Monte Carlo methods. Criticality experiments have also been carried out in many laboratories in Japan as well as overseas. By effectively using these study results, the Japanese Criticality Safety Handbook was published in 1988, almost the intermediate point of the last 50 years. An increased interest has been shown in criticality safety studies, and a Working Party on Nuclear Criticality Safety (WPNCS) was set up by the Nuclear Science Committee of Organisation Economic Co-operation and Development in 1997. WPNCS has several task forces in charge of each of the International Criticality Safety Benchmark Evaluation Program (ICSBEP), Subcritical Measurement, Experimental Needs, Burn-up Credit Studies and Minimum Critical Values. Criticality safety studies in Japan have been carried out in cooperation with WPNCS. This paper describes criticality safety study activities in Japan along with the contents of the Japanese Criticality Safety Handbook and the tasks of WPNCS. (author)

Windscale nuclear power development laboratories power ramp experience in the Winfrith SGHWR (UK)

International Nuclear Information System (INIS)

Garlick, A.; Sumerling, R.; Stuttard, A.; Bond, G.G.; Howl, D.A.; Fox, W.N.; Cordall, D.; Cornell, R.M.

SGHWR fuel has sufficient power ramping capability to permit considerable latitude in fuel management schemes. However, beyond some limiting ramping conditions, there is risk of fuel defecting. Controlled ramp experiments were therefore carried out in the reactor in order to determine the defect mechanism and define the fuel operating limitations. Cladding cracks produced during these power ramps are considered to have been a consequence of fission product stress-corrosion attack. A critical stress level for cracking, based on laboratory stress corrosion tests, have been used successfully in conjunction with computer codes to calculate cladding stresses and strains in fuel rods. Initial analysis of the conditions under which a fuel element defected at 11.6 MWd/kgU suggests that the threshold stress for failure may be decreased compared with elements at lower burn-up (5-6 MWd/kgU)

Scenarios for Low Carbon and Low Water Electric Power Plant Operations: Implications for Upstream Water Use.

Science.gov (United States)

Dodder, Rebecca S; Barnwell, Jessica T; Yelverton, William H

2016-11-01

Electric sector water use, in particular for thermoelectric operations, is a critical component of the water-energy nexus. On a life cycle basis per unit of electricity generated, operational (e.g., cooling system) water use is substantially higher than water demands for the fuel cycle (e.g., natural gas and coal) and power plant manufacturing (e.g., equipment and construction). However, could shifting toward low carbon and low water electric power operations create trade-offs across the electricity life cycle? We compare business-as-usual with scenarios of carbon reductions and water constraints using the MARKet ALlocation (MARKAL) energy system model. Our scenarios show that, for water withdrawals, the trade-offs are minimal: operational water use accounts for over 95% of life cycle withdrawals. For water consumption, however, this analysis identifies potential trade-offs under some scenarios. Nationally, water use for the fuel cycle and power plant manufacturing can reach up to 26% of the total life cycle consumption. In the western United States, nonoperational consumption can even exceed operational demands. In particular, water use for biomass feedstock irrigation and manufacturing/construction of solar power facilities could increase with high deployment. As the United States moves toward lower carbon electric power operations, consideration of shifting water demands can help avoid unintended consequences.

Operating Experience with Power Reactors. Proceedings of the Conference on Operating Experience with Power Reactors. Vol. I

Energy Technology Data Exchange (ETDEWEB)

NONE

1963-10-15

At the beginning of 1963 nuclear power plants produced some 3 500 000kW of electrical power to different distribution grids around the world. Much significant operating experience has been gained with these power reactors, but this experience is often not collected in such a way as to make it easily available. The International Atomic Energy Agency convened a Conference on Operating Experience with Power Reactors in Vienna from 4-8 June 1963 which was attended by 240 participants representing 27 of the Agency's Member States and six international organizations. At the Conference, 42 papers giving detailed experience with more than 20 nuclear power stations were discussed. Although similar meetings on a national or regional scale have been held earlier in various countries, this is the first arranged by the Agency on a world-wide basis. Some of the detailed material may have been given earlier but for the most part it represents new and recently acquired experience, and for the first time it has been possible to compile in one place such extensive material on the operating experience with power reactors. The Conference discussed the experience gained both generally in the context of national and international nuclear power development programmes, and more specifically in the detailed operating experience with different power reactor stations. In addition, various plant components, fuel cycles, staffing of nuclear plants and licensing of such staff were treated. It is hoped that these Proceedings will be of interest not only to nuclear plant designers and operators who daily encounter problems similar to those discussed by the Conference, but also to those guiding the planning and implementation of power development programmes.

Operating Experience with Power Reactors. Proceedings of the Conference on Operating Experience with Power Reactors. Vol. II

Energy Technology Data Exchange (ETDEWEB)

NONE

1963-10-15

At the beginning of 1963 nuclear power plants produced some 3 500 000 kW of electrical power to different distribution grids around the world. Much significant operating experience has been gained with these power reactors, but this experience is often not collected in such a way as to make it easily available. The International Atomic Energy Agency convened a Conference on Operating Experience with Power Reactors in Vienna from 4 -8 June 1963 which was attended by 240 participants representing 27 of the Agency's Member States and six international organizations. At the Conference, 42 papers giving detailed experience with more than 20 nuclear power stations were discussed. Although similar meetings on a national or regional scale have been held earlier in various countries, this is the first arranged by the Agency on a world-wide basis. Some of the detailed material may have been given earlier but for the most part it represents new and recently acquired experience, and for the first time it has been possible to compile in one place such extensive material on the operating experience with power reactors. The Conference discussed the experience gained both generally in the context of national and international nuclear power development programmes, and more specifically in the detailed operating experience with different power reactor stations. In addition, various plant components, fuel cycles, staffing of nuclear plants and licensing of such staff were treated. It is hoped that these Proceedings will be of interest not only to nuclear , plant designers and operators who daily encounter problems similar to those discussed by the Conference, but also to those guiding the planning and implementation of power development programmes.

Low-power non-volatile spintronic memory: STT-RAM and beyond

International Nuclear Information System (INIS)

Wang, K L; Alzate, J G; Khalili Amiri, P

2013-01-01

The quest for novel low-dissipation devices is one of the most critical for the future of semiconductor technology and nano-systems. The development of a low-power, universal memory will enable a new paradigm of non-volatile computation. Here we consider STT-RAM as one of the emerging candidates for low-power non-volatile memory. We show different configurations for STT memory and demonstrate strategies to optimize key performance parameters such as switching current and energy. The energy and scaling limits of STT-RAM are discussed, leading us to argue that alternative writing mechanisms may be required to achieve ultralow power dissipation, a necessary condition for direct integration with CMOS at the gate level for non-volatile logic purposes. As an example, we discuss the use of the giant spin Hall effect as a possible alternative to induce magnetization reversal in magnetic tunnel junctions using pure spin currents. Further, we concentrate on magnetoelectric effects, where electric fields are used instead of spin-polarized currents to manipulate the nanomagnets, as another candidate solution to address the challenges of energy efficiency and density. The possibility of an electric-field-controlled magnetoelectric RAM as a promising candidate for ultralow-power non-volatile memory is discussed in the light of experimental data demonstrating voltage-induced switching of the magnetization and reorientation of the magnetic easy axis by electric fields in nanomagnets. (paper)

From unwanted pregnancy to safe abortion: Sharing information about abortion in Asia through animation.

Science.gov (United States)

Krishnan, Shweta; Dalvie, Suchitra

2015-05-01

Although unsafe abortion continues to be a leading cause of maternal mortality in many countries in Asia, the right to safe abortion remains highly stigmatized across the region. The Asia Safe Abortion Partnership, a regional network advocating for safe abortion, produced an animated short film entitled From Unwanted Pregnancy to Safe Abortion to show in conferences, schools and meetings in order to share knowledge about the barriers to safe abortion in Asia and to facilitate conversations on the right to safe abortion. This paper describes the making of this film, its objectives, content, dissemination and how it has been used. Our experience highlights the advantages of using animated films in addressing highly politicized and sensitive issues like abortion. Animation helped to create powerful advocacy material that does not homogenize the experiences of women across a diverse region, and at the same time emphasize the need for joint activities that express solidarity. Copyright © 2015. Published by Elsevier Ltd.

SUNRAYCE 93: Working safely with lead-acid batteries and photovoltaic power systems

Energy Technology Data Exchange (ETDEWEB)

DePhillips, M.P.; Moskowitz, P.D.; Fthenakis, V.M.

1992-11-03

The US Department of Energy (DOE) is sponsoring SUNRAYCE 93 to advance tile technology and use of photovoltaics and electric vehicles. Participants will use cars powered by photovoltaic modules and lead-acid storage batteries. This brochure, prepared for students and faculty participating in this race, outlines the health hazards presented by these electrical systems, and gives guidance on strategies for their safe usage. At the outset, it should be noted that working with photovoltaic systems and batteries requires electric vehicle drivers and technicians to have {open_quotes}hands-on{close_quotes} contact with the car on a daily basis. It is important that no one work near a photovoltaic energy system or battery, either in a vehicle or on the bench, unless they familiarize themselves with the components in use, and know and observe safe work practices including the safety precautions described in the manuals provided by the various equipment vendors and this document.

The inherently-safe power reactor DYONISOS (Dynamic Nuclear Inherently-Safe Reactor Operating with Spheres)

International Nuclear Information System (INIS)

Taube, M.; Lanfranchi, M.; Weissenfluh, Th. von; Ligou, J.; Yadigaroglu, G.; Taube, P.

1986-01-01

A philosophy of inherent safety is formulated and an inherently-safe thermal power reactor is presented. Solid fuel in the form of spheres a few centimetres in diameter is suspended under the hydro-dynamic pressure of molten lead coolant in vertical channels within the graphite moderator. Loss of main pump pressure, or a loss-of-coolant accident (LOCA), results in immediate removal of the fuel to rigid sieves below the core, with consequent subcriticality. Residual and decay heat are carried away by thermal conduction through the coolant or, in the case of a LOCA, by a combination of radiation and natural convection of cover gas or incoming air from the fuel to the reactor vessel and convection of air between the vessel and steel containment wall. All decay heat removal systems are passive, though actively initiated external spray cooling of the containment can be used to reduce wall temperature. This, however, is only necessary in the case of a LOCA and after a period of 24 h. (author)

TRIGA criticality experiment for testing burn-up calculations

International Nuclear Information System (INIS)

Persic, Andreja; Ravnik, Matjaz; Zagar, Tomaz

1999-01-01

A criticality experiment with partly burned TRIGA fuel is described. 20 wt % enriched standard TRIGA fuel elements initially containing 12 wt % U are used. Their average burn-up is 1.4 MWd. Fuel element burn-up is calculated in 2-D four group diffusion approximation using TRIGLAV code. The burn-up of several fuel elements is also measured by reactivity method. The excess reactivity of several critical and subcritical core configurations is measured. Two core configurations contain the same fuel elements in the same arrangement as were used in the fresh TRIGA fuel criticality experiment performed in 1991. The results of the experiment may be applied for testing the computer codes used for fuel burn-up calculations. (author)

I/O Sharing in a Multi-core Kernel for Mixed-criticality Applications

DEFF Research Database (Denmark)

Li, Gang; Top, Søren

2013-01-01

In a mixed-criticality system, applications with different safety criticality levels are usually required to be implemented upon one platform for several reasons( reducing hardware cost, space, power consumption). Partitioning technology is used to enable the integration of mixed-criticality appl......In a mixed-criticality system, applications with different safety criticality levels are usually required to be implemented upon one platform for several reasons( reducing hardware cost, space, power consumption). Partitioning technology is used to enable the integration of mixed......, a certifiable I/O sharing approach is implemented based on a safe message mechanism, in order to support the partitioning architecture, enable individual certification of mixed-criticality applications and thus achieve minimized total certification cost of the entire system....

Los Alamos Critical Experiments Facility

International Nuclear Information System (INIS)

Malenfant, R.E.

1991-01-01

The Critical Experiments Facility of the Los Alamos National Laboratory has been in existence for 45 years. In that period of time, thousands of measurements have been made on assemblies containing every fissionable material in various configurations that included bare metal and compounds of the nitrate, sulfate, fluoride, carbide, and oxide. Techniques developed or applied include Rossi-α, source-jerk, rod oscillator, and replacement measurements. Many of the original measurements of delay neutrons were performed at the site, and a replica of the Hiroshima weapon was operated at steady state to assist in evaluating the relative biological effectiveness (RBE) of neutrons. Solid, liquid, and gas fissioning systems were run at critical. Operation of this original critical facility has demonstrated the margin of safety that can be obtained through remote operation. Eight accidental excursions have occurred on the site, ranging from 1.5 x 10 16 to 1.2 x 10 17 fissions, with no significant exposure to personnel or damage to the facility beyond the machines themselves -- and in only one case was the machine damaged beyond further use. The present status of the facility, operating procedures, and complement of machines will be described in the context of programmatic activity. New programs will focus on training, validation of criticality alarm systems, experimental safety assessment of process applications, and dosimetry. Special emphasis will be placed on the incorporation of experience from 45 years of operation into present procedures and programs. 3 refs

Developing Low-Power Transceiver Technologies for In Situ Communication Applications

Science.gov (United States)

Lay, N.; Cheetham, C.; Mojaradi, H.; Neal, J.

2001-07-01

For future deep-space missions, significant reductions in the mass and power requirements for short-range telecommunication systems will be critical in enabling a wide variety of new mission concepts. These possibilities include penetrators, gliders, miniature rovers, balloons, and sensor networks. The recent development activity reported in this article has focused on the design of ultra-low-mass and -power transceiver systems and subsystems suitable for operation in a flight environment. Under these efforts, the basic functionality of the transceiver has been targeted towards a Mars microprobe communications scenario. However, the overall transceiver architecture is well suited to any short- or medium-range application where a remote probe will aperiodically communicate with a base station, possibly an orbiter, for the eventual purpose of relaying science information back to Earth. Additionally, elements of the radio architecture can be applied in situations involving surface-to-surface communications, thereby enabling different mission communications topologies. Through a system analysis of these channels, both the applicability and benefit of very low power communications will be quantitatively addressed.

Evolvement of nuclear criticality safety programs

International Nuclear Information System (INIS)

Ketzlach, N.

1992-01-01

Nuclear criticality safety (NCS) has developed from a discipline requiring the services of personnel with only a background in reactor physics to that involving reactor physics, process engineering, and design as well as administration of the program to ensure all its requirements are implemented. When Oak Ridge National Laboratory (ORNL) was designed and constructed, the physicists at Los Alamos National Laboratory (LANL) were performing the criticality analyses. A physicist who had no chemical process or engineering experience was brought in from LANL to determine whether the facility would be safe. It was only because of his understanding of the reactor physics principles, scientific intuition, and some luck that the design and construction of the facility led to a safe plant. It took a number of years of experience with facility operations and the dedication of personnel for NCS to reach its present status as a recognized discipline

Water chemistry - one of the key technologies for safe and reliable nuclear power plant operation

International Nuclear Information System (INIS)

Uchida, S.; Otoha, K.; Ishigure, K.

2006-01-01

Full text: Full text: Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry, a) better reliability of reactor structures and fuels, b) lower occupational exposure, and c) fewer radwaste sources, should be simultaneously satisfied. The research committee related to water chemistry of the Atomic Energy Society of Japan has played important roles to enhance improvement in water chemistry control, to share knowledge and experience with water chemistry among plant operators and manufacturers, to establish common technological bases for plant water chemistry and then to transfer them to the next generation related to water chemistry. Furthermore, the committee has tried to contribute to arranging R and D proposals for further improvement in water chemistry control through road map planning

Converter Power Density Increase using Low Inductive Integrated DC-link Capacitor/Bus

DEFF Research Database (Denmark)

Trintis, Ionut; Franke, Toke; Rannested, Bjørn

2015-01-01

The power losses in switching devices have a direct effect on the maximum converter power. For a voltage source converter, the DC-link bus has a major influence on the power loss and safe operating area of the power devices. The Power Ring Film CapacitorTM integrated with an optimized bus structu...

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)

Low Power Design with High-Level Power Estimation and Power-Aware Synthesis

CERN Document Server

Ahuja, Sumit; Shukla, Sandeep Kumar

2012-01-01

Low-power ASIC/FPGA based designs are important due to the need for extended battery life, reduced form factor, and lower packaging and cooling costs for electronic devices. These products require fast turnaround time because of the increasing demand for handheld electronic devices such as cell-phones, PDAs and high performance machines for data centers. To achieve short time to market, design flows must facilitate a much shortened time-to-product requirement. High-level modeling, architectural exploration and direct synthesis of design from high level description enable this design process. This book presents novel research techniques, algorithms,methodologies and experimental results for high level power estimation and power aware high-level synthesis. Readers will learn to apply such techniques to enable design flows resulting in shorter time to market and successful low power ASIC/FPGA design. Integrates power estimation and reduction for high level synthesis, with low-power, high-level design; Shows spec...

Investigation on the Short Circuit Safe Operation Area of SiC MOSFET Power Modules

DEFF Research Database (Denmark)

Reigosa, Paula Diaz; Luo, Haoze; Iannuzzo, Francesco

2016-01-01

This paper gives a better insight of the short circuit capability of state-of-the-art SiC MOSFET power modules rated at 1.2 kV by highlighting the physical limits under different operating conditions. Two different failure mechanisms have been identified, both reducing the short-circuit capability...... of SiC power modules in respect to discrete SiC devices. Based on such failure mechanisms, two short circuit criteria (i.e., short circuit current-based criterion and gate voltage-based criterion) are proposed in order to ensure their robustness under short-circuit conditions. A Safe Operation Area (SOA...

A Short-Circuit Safe Operation Area Identification Criterion for SiC MOSFET Power Modules

DEFF Research Database (Denmark)

Reigosa, Paula Diaz; Iannuzzo, Francesco; Luo, Haoze

2017-01-01

This paper proposes a new method for the investigation of the short-circuit safe operation area (SCSOA) of state-of-the-art SiC MOSFET power modules rated at 1.2 kV based on the variations in SiC MOSFET electrical parameters (e.g., short-circuit current and gate–source voltage). According...... to the experimental results, two different failure mechanisms have been identified, both reducing the short-circuit capability of SiC power modules with respect to discrete SiC devices. Based on such failure mechanisms, two short-circuit safety criteria have been formulated: 1) the short-circuit...

Ageing management of nuclear power plant - the Tarapur experience

International Nuclear Information System (INIS)

Anilkumar, K.R.; Das, P.K.; Bhattacharjee, S.; Ramamurty, U.

2006-01-01

Tarapur Atomic Power Station, the longest serving Nuclear Power Plant in the Asian continent has completed 36 years of successful operation and generated more than 70,000 million units of electric power. Built in late sixties, with the state-of-the-art safety features prevailing then, TAPS through the process of evolution has become safer plant due to efforts of upgradation, renovation and refurbishment prompted by the station's operating experience, feed back from overseas reactors, lessons learnt from nuclear incidents, accidents and fresh review of design basis and safety analysis of the plant. All components of a Nuclear power plant experience some degradation with time. The Reactor Pressure Vessels (RPV) designed for 40 effective full power years (EFPY) of operation have operated for less than 20 EFPY and the material condition is assessed to be fit for some more years of service. The condition of the containment and main plant buildings was assessed to be satisfactory. The Ageing Management Programme (AMP) involved identification of key systems, structures and components (SSCs) that may experience degradation due to ageing, and take corrective measures through maintenance, repair and/or replacement. The identified components were classified as major critical components, important systems and other critical components. For each component mode of degradation was identified, ageing assessment was done and action plan was finalized. Replacement of some important equipment like 3 x 50 % capacity Emergency Diesel Generators (EDG) with 3 x 100 % capacity EDG, Salt Service Water (SSW) pumps, Control rod drive (CRD) pumps, Emergency Condenser tube bundles, Station battery has been done on the basis of condition monitoring and to obviate common cause failure and enhance the system reliability. Samples of Safety related cables were subjected to residual life assessment (RLA) and replacement action firmed up on the basis of the RLA findings. Condition survey of Main

Calculational assessment of critical experiments with mixed-oxide fuel pin arrays moderated by organic solution

International Nuclear Information System (INIS)

Smolen, G.R.; Funabashi, H.

1987-01-01

Critical experiments have been conducted with organically moderated mixed-oxide (MOX) fuel pin assemblies at the Pacific Northwest Lab. Critical Mass Lab. These experiments are part of a joint exchange program between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corp. of Japan in the area of criticality data development. The purpose of these experiments is to benchmark computer codes and cross-section libraries and to assess the reactivity difference between systems moderated by water and those moderated by an organic solution. Past studies have indicated that some organic mixtures may be better moderators than water. This topic is of particular importance to the criticality safety of fuel processing plants where fissile material is dissolved in organic solutions during the solvent extraction process. In the past, it has been assumed that the codes and libraries benchmarked with water-moderated experiments were adequate when performing design and licensing studies of organically moderated systems. Calculations presented in this paper indicated that the Scale code system and the 27-energy-group cross-section library accurately compute k/sub eff/ for organically moderated MOX fuel pin assemblies. Furthermore, the reactivity of an organic solution with a 32 vol % TBP/68 vol% NPH mixture in a heterogeneous configuration is the same, for practical purposes, as water

Calculational assessment of critical experiments with mixed oxide fuel pin arrays moderated by organic solution

International Nuclear Information System (INIS)

Smolen, G.R.

1987-01-01

Critical experiments have been conducted with organic-moderated mixed oxide (MOX) fuel pin assemblies at the Pacific Northwest Laboratory (PNL) Critical Mass Laboratory (CML). These experiments are part of a joint exchange program between the United States Department of Energy (USDOE) and the Power Reactor and Nuclear Fuel Development Corporation (PNC) of Japan in the area of criticality data development. The purpose of these experiments is to benchmark computer codes and cross-section libraries and to assess the reactivity difference between systems moderated by water and those moderated by an organic solution. Past studies have indicated that some organic mixtures may be better moderators than water. This topic is of particular importance to the criticality safety of fuel processing plants where fissile material is dissolved in organic solutions during the solvent extraction process. In the past, it has been assumed that the codes and libraries benchmarked with water-moderated experiments were adequate when performing design and licensing studies of organic-moderated systems. Calculations presented in this paper indicated that the SCALE code system and the 27-energy-group cross-section accurately compute k-effectives for organic moderated MOX fuel-pin assemblies. Furthermore, the reactivity of an organic solution with a 32-vol-% TBP/68-vol-% NPH mixture in a heterogeneous configuration is the same, for practical purposes, as water. 5 refs

Handbook of critical experiments benchmarks

International Nuclear Information System (INIS)

Durst, B.M.; Bierman, S.R.; Clayton, E.D.

1978-03-01

Data from critical experiments have been collected together for use as benchmarks in evaluating calculational techniques and nuclear data. These benchmarks have been selected from the numerous experiments performed on homogeneous plutonium systems. No attempt has been made to reproduce all of the data that exists. The primary objective in the collection of these data is to present representative experimental data defined in a concise, standardized format that can easily be translated into computer code input

Prompt neutron decay constant estimation of RSG-GAS at high power noise experiment

International Nuclear Information System (INIS)

Jujuratisbela, U.; Kristedjo; Tukiran; Pinem, S.; Iman, J.; Puryono; Sanjaya, A.; Suwarno

1998-01-01

The determination of prompt neutron decay constant (α) of RGS-GAS by using low power noise experiment method at the equilibrium core indicated that the result is not good. The bad result was due to the small ratio of the noise signal to background which was caused by low detector efficiency or contaminated core after long time operation. To solve the problem is tried by using noise experiment technique at high power. The voltage output of neutron detectors at power of 5, 12, and 23 MW were connected to preamplifier and filter then to the Dynamic Signal Analyzer Version-2 and then the power spectral density of each channel of JKT04 and JKT03, the cut off frequency of each channel can be determined by using linear regression technique such that the prompt neutron decay constant can be estimated

Method of critical power prediction based on film flow model coupled with subchannel analysis

International Nuclear Information System (INIS)

Tomiyama, Akio; Yokomizo, Osamu; Yoshimoto, Yuichiro; Sugawara, Satoshi.

1988-01-01

A new method was developed to predict critical powers for a wide variety of BWR fuel bundle designs. This method couples subchannel analysis with a liquid film flow model, instead of taking the conventional way which couples subchannel analysis with critical heat flux correlations. Flow and quality distributions in a bundle are estimated by the subchannel analysis. Using these distributions, film flow rates along fuel rods are then calculated with the film flow model. Dryout is assumed to occur where one of the film flows disappears. This method is expected to give much better adaptability to variations in geometry, heat flux, flow rate and quality distributions than the conventional methods. In order to verify the method, critical power data under BWR conditions were analyzed. Measured and calculated critical powers agreed to within ±7%. Furthermore critical power data for a tight-latticed bundle obtained by LeTourneau et al. were compared with critical powers calculated by the present method and two conventional methods, CISE correlation and subchannel analysis coupled with the CISE correlation. It was confirmed that the present method can predict critical powers more accurately than the conventional methods. (author)

Experiments on criticality carried out from 1975 till 1980

International Nuclear Information System (INIS)

Heinicke, W.; Tischer, A.; Weber, W.J.

1981-11-01

The report on hand includes the experiments on criticality published from 1975 till 1980. About 90 experiments with the most important related data are listed. They are capable of being called up, with the data base system KRITEXP, by 14 different descriptors or printed in any arrangement or order. This is the basis for a global or purposeful verification of the calculating method for criticality safety. The proof of reliability of the calculations for the criticality analysis are immediately relevant for the licencing procedure under atomic law for all plants of the nuclear fuel cycle where nuclear fuels are handled. Since no criticality experiments are being carried out in the Federal Republic of Germany, the data collection on hand will help to fill this gap with regard to the assessment of experiments carried out in other countries. (orig.) [de

Criticality Safety Basics for INL FMHs and CSOs

Energy Technology Data Exchange (ETDEWEB)

V. L. Putman

2012-04-01

Nuclear power is a valuable and efficient energy alternative in our energy-intensive society. However, material that can generate nuclear power has properties that require this material be handled with caution. If improperly handled, a criticality accident could result, which could severely harm workers. This document is a modular self-study guide about Criticality Safety Principles. This guide's purpose it to help you work safely in areas where fissionable nuclear materials may be present, avoiding the severe radiological and programmatic impacts of a criticality accident. It is designed to stress the fundamental physical concepts behind criticality controls and the importance of criticality safety when handling fissionable materials outside nuclear reactors. This study guide was developed for fissionable-material-handler and criticality-safety-officer candidates to use with related web-based course 00INL189, BEA Criticality Safety Principles, and to help prepare for the course exams. These individuals must understand basic information presented here. This guide may also be useful to other Idaho National Laboratory personnel who must know criticality safety basics to perform their assignments safely or to design critically safe equipment or operations. This guide also includes additional information that will not be included in 00INL189 tests. The additional information is in appendices and paragraphs with headings that begin with 'Did you know,' or with, 'Been there Done that'. Fissionable-material-handler and criticality-safety-officer candidates may review additional information at their own discretion. This guide is revised as needed to reflect program changes, user requests, and better information. Issued in 2006, Revision 0 established the basic text and integrated various programs from former contractors. Revision 1 incorporates operation and program changes implemented since 2006. It also incorporates suggestions, clarifications

Magnetocaloric properties and critical behavior of high relative cooling power FeNiB nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chaudhary, V. [Interdisciplinary Graduate School, Nanyang Technological University, Singapore 639798 (Singapore); Energy Research Institute @NTU, Nanyang Technological University, Singapore 637553 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Maheswar Repaka, D. V.; Chaturvedi, A.; Ramanujan, R. V., E-mail: ramanujan@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Sridhar, I. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

2014-10-28

Low cost magnetocaloric nanomaterials have attracted considerable attention for energy efficient applications. We report a very high relative cooling power (RCP) in a study of the magnetocaloric effect in quenched FeNiB nanoparticles. RCP increases from 89.8 to 640 J kg{sup −1} for a field change of 1 and 5 T, respectively, these values are the largest for rare earth free iron based magnetocaloric nanomaterials. To investigate the magnetocaloric behavior around the Curie temperature (T{sub C}), the critical behavior of these quenched nanoparticles was studied. Detailed analysis of the magnetic phase transition using the modified Arrott plot, Kouvel-Fisher method, and critical isotherm plots yields critical exponents of β = 0.364, γ = 1.319, δ = 4.623, and α = −0.055, which are close to the theoretical exponents obtained from the 3D-Heisenberg model. Our results indicate that these FeNiB nanoparticles are potential candidates for magnetocaloric fluid based heat pumps and low grade waste heat recovery.

Influence of “whirlwind” mixing grids on the critical power of WWER fuel assembly

International Nuclear Information System (INIS)

Selivanov, Yu.F.; Pomet'ko, R.S.; Volkov, S.E.

2014-01-01

The problem of optimizing the number and placement of lattices in different types assemblies is discussed. The effect of the amount of mixing lattices and their locations in assemblies on the conditions of occurrence of boiling crisis in the fuel assembly on its critical power (power of assembly in case of boiling crisis) is studied. Experiments were carried out with the use of freon as a coolant. It is recommended simultaneous use in the assembly of lattices of “whirlwind” type, well-intensifying heat exchange, and cell lattices of “pass” type (or lattices with deflectors) affecting on moving flow, provided the optimal location of lattices in the assembly [ru

Critical power for self-focusing of optical beam in absorbing media

Science.gov (United States)

Qi, Pengfei; Zhang, Lin; Lin, Lie; Zhang, Nan; Wang, Yan; Liu, Weiwei

2018-04-01

Self-focusing effects are of central importance for most nonlinear optical effects. The critical power for self-focusing is commonly investigated theoretically without considering a material’s absorption. Although this is practicable for various materials, investigating the critical power for self-focusing in media with non-negligible absorption is also necessary, because this is the situation usually met in practice. In this paper, the simple analytical expressions describing the relationships among incident power, absorption coefficient and focal position are provided by a simple physical model based on the Fermat principle. Expressions for the absorption dependent critical power are also derived; these can play important roles in experimental and applied research on self-focusing-related nonlinear optical phenomena in absorbing media. Numerical results, based on the nonlinear wave equation—and which can predict experimental results perfectly—are also presented, and agree quantitatively with the analytical results proposed in this paper.

The overvoltage protection module for the power supply system for the pixel detector at Belle II experiment at KEK

International Nuclear Information System (INIS)

Kapusta, P.; Kisielewski, B.

2015-01-01

In this paper the overvoltage protection modules (OVP) for the power supply (PS) system of the Belle II pixel detector (PXD) are described. The aim of the OVP is to protect the detector and associated electronics against overvoltage conditions. Most critical in the system are voltages supplying the front-end ASICs. The PXD detector consists of the DEPFET sensor modules with integrated chips like the Drain Current Digitizer, the Switcher and the Data Handling Processor. These chips, implemented in modern sub-micron technologies, are quite vulnerable to variations in the supply voltages. The PXD will be placed in the Belle II experiment as close as possible to the interaction point, where access during experiment is very limited or even impossible, thus the PS and OVP systems exploit the remote-sensing method. Overvoltage conditions are due to failures of the PS itself, wrong setting of the output voltages or transient voltages coming out of hard noisy environment of the experiment. The OVP modules are parts of the PS modules. For powering the PXD 40 PS modules are placed 15 m outside the Belle II spectrometer. Each one is equipped with the OVP board. All voltages (22) are grouped in 4 domains: Analog, Digital, Steering and Gate which have independent grounds. The OVP boards are designed from integrated circuits from Linear Technology. All configurations were simulated with the Spice program. The control electronics is designed in a Xilinx CPLD. Two types of integrated circuits were used. LT4356 surge stopper protects loads from high voltage transients. The output voltages are limited to a safe value and also protect loads against over current faults. For less critical voltages, the LTC2912 voltage monitors are used that detect under-voltage and overvoltage events. It has to be noted that the OVP system is working independently of any other protection of the PS system, which increases its overall reliability. (authors)

The overvoltage protection module for the power supply system for the pixel detector at Belle II experiment at KEK

Energy Technology Data Exchange (ETDEWEB)

Kapusta, P.; Kisielewski, B. [Institute of Nuclear Physics PAN, ul.Radzikowskiego 152, 31-875 Krakow, (Poland)

2015-07-01

In this paper the overvoltage protection modules (OVP) for the power supply (PS) system of the Belle II pixel detector (PXD) are described. The aim of the OVP is to protect the detector and associated electronics against overvoltage conditions. Most critical in the system are voltages supplying the front-end ASICs. The PXD detector consists of the DEPFET sensor modules with integrated chips like the Drain Current Digitizer, the Switcher and the Data Handling Processor. These chips, implemented in modern sub-micron technologies, are quite vulnerable to variations in the supply voltages. The PXD will be placed in the Belle II experiment as close as possible to the interaction point, where access during experiment is very limited or even impossible, thus the PS and OVP systems exploit the remote-sensing method. Overvoltage conditions are due to failures of the PS itself, wrong setting of the output voltages or transient voltages coming out of hard noisy environment of the experiment. The OVP modules are parts of the PS modules. For powering the PXD 40 PS modules are placed 15 m outside the Belle II spectrometer. Each one is equipped with the OVP board. All voltages (22) are grouped in 4 domains: Analog, Digital, Steering and Gate which have independent grounds. The OVP boards are designed from integrated circuits from Linear Technology. All configurations were simulated with the Spice program. The control electronics is designed in a Xilinx CPLD. Two types of integrated circuits were used. LT4356 surge stopper protects loads from high voltage transients. The output voltages are limited to a safe value and also protect loads against over current faults. For less critical voltages, the LTC2912 voltage monitors are used that detect under-voltage and overvoltage events. It has to be noted that the OVP system is working independently of any other protection of the PS system, which increases its overall reliability. (authors)

Battery-powered pulsed high density inductively coupled plasma source for pre-ionization in laboratory astrophysics experiments.

Science.gov (United States)

Chaplin, Vernon H; Bellan, Paul M

2015-07-01

An electrically floating radiofrequency (RF) pre-ionization plasma source has been developed to enable neutral gas breakdown at lower pressures and to access new experimental regimes in the Caltech laboratory astrophysics experiments. The source uses a customized 13.56 MHz class D RF power amplifier that is powered by AA batteries, allowing it to safely float at 3-6 kV with the electrodes of the high voltage pulsed power experiments. The amplifier, which is capable of 3 kW output power in pulsed (<1 ms) operation, couples electrical energy to the plasma through an antenna external to the 1.1 cm radius discharge tube. By comparing the predictions of a global equilibrium discharge model with the measured scalings of plasma density with RF power input and axial magnetic field strength, we demonstrate that inductive coupling (rather than capacitive coupling or wave damping) is the dominant energy transfer mechanism. Peak ion densities exceeding 5 × 10(19) m(-3) in argon gas at 30 mTorr have been achieved with and without a background field. Installation of the pre-ionization source on a magnetohydrodynamically driven jet experiment reduced the breakdown time and jitter and allowed for the creation of hotter, faster argon plasma jets than was previously possible.

Consistent Set of Experiments from ICSBEP Handbook for Evaluation of Criticality Calculation Prediction of Apparatus of External Fuel Cycle with Different Fuel

Energy Technology Data Exchange (ETDEWEB)

Golovko, Yury E. [FSUE ' SSC RF-IPPE' , 249033, Bondarenko Square 1, Obninsk (Russian Federation)

2008-07-01

Experiments with plutonium, low enriched uranium and uranium-233 from the ICSBEP1 Handbook are being considered in this paper. Among these experiments it was selected only those, which seem to be the most relevant to the evaluation of uncertainty of critical mass of mixtures of plutonium or low enriched uranium or uranium-233 with light water. All selected experiments were examined and covariance matrices of criticality uncertainties were developed along with some uncertainties were revised. Statistical analysis of these experiments was performed and some contradictions were discovered and eliminated. Evaluation of accuracy of prediction of criticality calculations was performed using the internally consistent set of experiments with plutonium, low enriched uranium and uranium-233 remained after the statistical analyses. The application objects for the evaluation of calculational prediction of criticality were water-reflected spherical systems of homogeneous aqueous mixtures of plutonium or low enriched uranium or uranium-233 of different concentrations which are simplified models of apparatus of external fuel cycle. It is shows that the procedure allows to considerably reduce uncertainty in k{sub eff} caused by the uncertainties in neutron cross-sections. Also it is shows that the results are practically independent of initial covariance matrices of nuclear data uncertainties. (authors)

30 years of experience in safe transportation of nuclear materials

International Nuclear Information System (INIS)

Kaneko, K.

2004-01-01

In April 2003, Nuclear Fuel Transport Co., Ltd. (NFT) marked the 30 th anniversary of its founding. NFT was established in 1973 and in 1978, commenced SF transport to the reprocessing plant in Tokai-mura. And then, after making preparations to transport nuclear materials to the various facilities at the Nuclear Fuel Cycle Center in Rokkasho-mura, NFT successfully started transportation of LLW (low level waste) to Rokksho-mura's LLW disposal center in 1992, domestic land transportation of HLW returned from overseas to the HLW storage center in 1995, domestic land transportation of natural hexafluoride delivered from overseas to the uranium enrichment plant in 1996, and transportation of SF to the reprocessing plant in 2000. NFT has realized an annual SF transportation capacity of 300 MTU and is currently making great company wide efforts to meet the Rokkasho Reprocessing Plant's future SF annual reprocessing capacity of 800MTU. At the end of FY2003, NFT had successfully transported 560 casks (about 1,730 MTU) of SF in more than 200 voyages in total, about 160,000 drums of LLW in around 100 voyages in total. This paper introduces the record of safe transport and its experience over the past 30 years and prospect for future transport business

30 years of experience in safe transportation of nuclear materials

Energy Technology Data Exchange (ETDEWEB)

Kaneko, K. [Nuclear Fuel Transport Co., Ltd., Tokyo (Japan)

2004-07-01

In April 2003, Nuclear Fuel Transport Co., Ltd. (NFT) marked the 30{sup th} anniversary of its founding. NFT was established in 1973 and in 1978, commenced SF transport to the reprocessing plant in Tokai-mura. And then, after making preparations to transport nuclear materials to the various facilities at the Nuclear Fuel Cycle Center in Rokkasho-mura, NFT successfully started transportation of LLW (low level waste) to Rokksho-mura's LLW disposal center in 1992, domestic land transportation of HLW returned from overseas to the HLW storage center in 1995, domestic land transportation of natural hexafluoride delivered from overseas to the uranium enrichment plant in 1996, and transportation of SF to the reprocessing plant in 2000. NFT has realized an annual SF transportation capacity of 300 MTU and is currently making great company wide efforts to meet the Rokkasho Reprocessing Plant's future SF annual reprocessing capacity of 800MTU. At the end of FY2003, NFT had successfully transported 560 casks (about 1,730 MTU) of SF in more than 200 voyages in total, about 160,000 drums of LLW in around 100 voyages in total. This paper introduces the record of safe transport and its experience over the past 30 years and prospect for future transport business.

Critical experiments on enriched uranium graphite moderated cores

International Nuclear Information System (INIS)

Kaneko, Yoshihiko; Akino, Fujiyoshi; Kitadate, Kenji; Kurokawa, Ryosuke

1978-07-01

A variety of 20 % enriched uranium loaded and graphite-moderated cores consisting of the different lattice cells in a wide range of the carbon to uranium atomic ratio have been built at Semi-Homogeneous Critical Experimental Assembly (SHE) to perform the critical experiments systematically. In the present report, the experimental results for homogeneously or heterogeneously fuel loaded cores and for simulation core of the experimental reactor for a multi-purpose high temperature reactor are filed so as to be utilized for evaluating the accuracy of core design calculation for the experimental reactor. The filed experimental data are composed of critical masses of uranium, kinetic parameters, reactivity worths of the experimental control rods and power distributions in the cores with those rods. Theoretical analyses are made for the experimental data by adopting a simple ''homogenized cylindrical core model'' using the nuclear data of ENDF/B-III, which treats the neutron behaviour after smearing the lattice cell structure. It is made clear from a comparison between the measurement and the calculation that the group constants and fundamental methods of calculations, based on this theoretical model, are valid for the homogeneously fuel loaded cores, but not for both of the heterogeneously fuel loaded cores and the core for simulation of the experimental reactor. Then, it is pointed out that consideration to semi-homogeneous property of the lattice cells for reactor neutrons is essential for high temperature graphite-moderated reactors using dispersion fuel elements of graphite and uranium. (author)

Critical experiments analysis by ABBN-90 constant system

Energy Technology Data Exchange (ETDEWEB)

Tsiboulia, A.; Nikolaev, M.N.; Golubev, V. [Institute of Physics and Power Engineering, Obninsk (Russian Federation)] [and others

1997-06-01

The ABBN-90 is a new version of the well-known Russian group-constant system ABBN. Included constants were calculated based on files of evaluated nuclear data from the BROND-2, ENDF/B-VI, and JENDL-3 libraries. The ABBN-90 is intended for the calculation of different types of nuclear reactors and radiation shielding. Calculations of criticality safety and reactivity accidents are also provided by using this constant set. Validation of the ABBN-90 set was made by using a computerized bank of evaluated critical experiments. This bank includes the results of experiments conducted in Russia and abroad of compact spherical assemblies with different reflectors, fast critical assemblies, and fuel/water-solution criticalities. This report presents the results of the calculational analysis of the whole collection of critical experiments. All calculations were produced with the ABBN-90 group-constant system. Revealed discrepancies between experimental and calculational results and their possible reasons are discussed. The codes and archives INDECS system is also described. This system includes three computerized banks: LEMEX, which consists of evaluated experiments and their calculational results; LSENS, which consists of sensitivity coefficients; and LUND, which consists of group-constant covariance matrices. The INDECS system permits us to estimate the accuracy of neutronics calculations. A discussion of the reliability of such estimations is finally presented. 16 figs.

Power and Ideology in American Sport. A Critical Perspective.

Science.gov (United States)

Sage, George H.

This book offers a critical perspective in examining how the dominant power interests influence sport and its role in society. It provides insights into how government, big business, the mass media, and educational institutions gain and maintain power and wealth while sport participants and spectators look to sport for enjoyment, creative…

NRC data base for power reactor surveillance programs and for irradiation experiments results

International Nuclear Information System (INIS)

Kam, F.B.K.; Stallmann, F.W.

1991-01-01

The radiation damage of pressure vessel materials in nuclear reactors depends on many different factors, primarily fluence, fluence spectrum, fluence rate, irradiation temperature, and chemistry. These factors and, possibly, others such as heat treatment and type of flux used in weldments must be considered to reliably predict the pressure vessel embrittlement and to assure the safe operation of the reactor. Based on embrittlement predictions, decisions must be made concerning operating parameters, low-leakage fuel management, possible life extension, and the need for annealing of the pressure vessel. Large numbers of data obtained from surveillance capsules and test reactor experiments are needed, comprising many different materials and different irradiation conditions, to develop generally applicable damage prediction models that can be used for industry standards and regulatory guides. The US Nuclear Regulatory Agency has, therefore, sponsored a project to construct an Embrittlement Data Base (EDB) for a comprehensive collection of data concerning changes in material properties of pressure vessel steels due to neutron irradiation. A first version containing data from surveillance capsules of commercial power reactors, the Power Reactor Embrittlement Data Base (PR-EDB) Version 1, has been completed and is available to authorized users from the Radiation Shielding Information Center at the Oak Ridge National Laboratory. This document provides a discussion of the features of the current database. 1 fig

Safe Software for Space Applications: Building on the DO-178 Experience

Science.gov (United States)

Dorsey, Cheryl A.; Dorsey, Timothy A.

2013-09-01

DO-178, Software Considerations in Airborne Systems and Equipment Certification, is the well-known international standard dealing with the assurance of software used in airborne systems [1,2]. Insights into the DO-178 experiences, strengths and weaknesses can benefit the international space community. As DO-178 is an excellent standard for safe software development when used appropriately, this paper provides lessons learned and suggestions for using it effectively.

Management of nuclear power plants for safe operation

International Nuclear Information System (INIS)

1984-01-01

This Guide identifies the main objectives and responsibilities of management with respect to safe operation of nuclear power plants. The Guide discusses the factors to be considered in structuring the operating organization to meet these objectives, to establish the management programmes that assure the safety tasks are performed, and to see that the services and facilities needed to accomplish the tasks are available. The Guide is primarily addressed to safety matters directly related to the operating phase. It assumes, in other words, that the safety aspects of siting, design, manufacturing and construction have been resolved. However, it also covers the interrelationships between operations and design, construction and commissioning, including the involvement of the operating organization in appropriate reviews of safety issues with reference to the future operating phase. The Guide is mainly restricted to matters of principle in relation to management-level decision making aimed at establishing safety policies. It is therefore not suitable for implementing such policies at the operational level. The IAEA Codes of Practice and Safety Guides provide detailed guidance for the latter purpose in those areas considered appropriate

Ontario-U.S. power outages : impacts on critical infrastructure

International Nuclear Information System (INIS)

2006-01-01

This paper described the power outage and resulting blackout that occurred on August 14, 2003 and identified how critical infrastructure was directly and interdependently impacted in Canada. The aim of the paper was to assist critical infrastructure protection and emergency management professionals in assessing the potential impacts of large-scale critical infrastructure disruptions. Information for the study was acquired from Canadian and American media reports and cross-sectoral information sharing with provincial and federal governments and the private sector. The blackout impacted most of the sources and means of generating, transmitting and distributing power within the area, which in turn impacted all critical infrastructure sectors. Landline and cellular companies experienced operational difficulties, which meant that emergency responders were impacted. Newspapers and the electronic media struggled to release information to the public. The banking and finance industry experienced an immediate degradation of services. The power outage caused shipping and storage difficulties for commercial retailers and dairy producers. A number of incidents were reported where only partially treated waste water was released into neighbouring waterways. The timing of the blackout coincided with the closures of workplaces and created additional difficulties on transportation networks. Many gas station pumps were inoperable. Police, fire departments and ambulance services experienced a dramatic increase in the volume of calls received, and all branches of the emergency services sector encountered transportation delays and difficulties with communications equipment. Nuclear reactors were also impacted. An estimated 150,000 Government of Canada employees were unable to report to work. Estimates have indicated that the power outage cost Ontario's economy between $1 and $2 billion. The outage negatively impacted 82 per cent of small businesses in Ontario. 170 refs., 3 figs

Criticality experiments with fast flux test facility fuel pins

International Nuclear Information System (INIS)

Bierman, S.R.

1990-11-01

A United States Department of Energy program was initiated during the early seventies at the Hanford Critical Mass Laboratory to obtain experimental criticality data in support of the Liquid Metal Fast Breeder Reactor Program. The criticality experiments program was to provide basic physics data for clean well defined conditions expected to be encountered in the handling of plutonium-uranium fuel mixtures outside reactors. One task of this criticality experiments program was concerned with obtaining data on PuO 2 -UO 2 fuel rods containing 20--30 wt % plutonium. To obtain this data a series of experiments were performed over a period of about twelve years. The experimental data obtained during this time are summarized and the associated experimental assemblies are described. 8 refs., 7 figs

Jezebel: Reconstructing a Critical Experiment from 60 Years Ago

Energy Technology Data Exchange (ETDEWEB)

Favorite, Jeffrey A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-15

The Jezebel experiment of 1954-1955 was a very small, nearly-spherical, nearly-bare (unreflected), nearly-homogeneous assembly of plutonium alloyed with gallium. This experiment was used to determine the critical mass of spherical, bare, homogeneous Pu-alloy. In 1956, the critical mass of Pu-alloy was determined to be 16.45 ± 0.05 kg. The experiment was reevaluated in 1969 using logbooks from the 1950s and updated nuclear cross sections. The critical mass of Pu-alloy was determined to be 16.57 ± 0.10 kg. In 2013, the ²³⁹Pu Jezebel experiment was again reevaluated, this time using detailed geometry and materials models and modern nuclear cross sections in high-fidelity Monte Carlo neutron transport calculations. Documentation from the 1950s was often inconsistent or missing altogether, and assumptions had to be made. The critical mass of Pu-alloy was determined to be 16.624 ± 0.075 kg. Historic documents were subsequently found that validated some of the 2013 assumptions and invalidated others. In 2016, the newly found information was used to once again reevaluate the ²³⁹Pu Jezebel experiment. The critical mass of Pu-alloy was determined to be 16.624 ± 0.065 kg. This talk will discuss each of these evaluations, focusing on the calculation of the uncertainty as well as the critical mass. We call attention to the ambiguity, consternation, despair, and euphoria involved in reconstructing the historic Jezebel experiment. This talk is quite accessible for undergraduate students as well as non-majors.

Delay-Tolerant, Low-Power Protocols for Large Security-Critical Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Claudio S. Malavenda

2012-01-01

Full Text Available This paper reports the analysis, implementation, and experimental testing of a delay-tolerant and energy-aware protocol for a wireless sensor node, oriented to security applications. The solution proposed takes advantages from different domains considering as a guideline the low power consumption and facing the problems of seamless and lossy connectivity offered by the wireless medium along with very limited resources offered by a wireless network node. The paper is organized as follows: first we give an overview on delay-tolerant wireless sensor networking (DTN; then we perform a simulation-based comparative analysis of state-of-the-art DTN approaches and illustrate the improvement offered by the proposed protocol; finally we present experimental data gathered from the implementation of the proposed protocol on a proprietary hardware node.

Indirect Control of a low power Single-Phase Active Power Filter

Directory of Open Access Journals (Sweden)

SILVIU EPURE

2010-12-01

Full Text Available This paper deals with a low power, single phase active filter used to compensate nonlinear loads. The filter uses the indirect control method and it is based on a particular connection between filter, polluting load and grid to avoid timeconsuming mathematic operations or signal processing computations and assures good rejection of harmonic currents injected by the nonlinear load into the grid. A scale model was first simulated in Simulink and then physically implemented. The paper presents simulation and experimental results, and highlight problems encountered during experiments.

Safe use of the Institute of Nuclear Physics reactor with low enriched fuel

International Nuclear Information System (INIS)

Baytelesov, S.A.; Dosimbaev, A.A.; Koblik, Yu.N.; Salikhbaev, U.S.; Khalikov, U.A.; Yuldashev, B.S.

2006-01-01

Full text: The requirements for safe exploitation of reactor do not accept boiling of water on the surface of fuel elements. At determination of safe thermal regime of reactor (permissible level of power) the regime of the most heat-stressed fuel assembly (FA) in the active core was analyzed. By using ASTRA code [1] the heat-stressed sector is determined by most heat-stressed FA. In calculations the power of reactor was selected so that stock factor prior to the water boiling on the FA surface was not less than 1.45. Besides, in calculations the value of maximal energy density in examined FA is decreased by 10 %. As the part of the energy generated in the FA cores will be lost in constructional materials of the active zone and on the reflector. The stocks of safety before occurrence of instability of flow in gaps between of FA and before crisis of heat exchange are also analyzed. Further, by using the MCNP-4C code [2], densities of fast (E > 0,821 MeV) and thermal flows (E < 0,625 eV) of neutrons were calculated for those experimental channels where the irradiation of samples would be carried out. (author)

Safe nuclear power

International Nuclear Information System (INIS)

Cady, K.B.

1992-01-01

Nearly 22 percent of the electricity generated in the United States already comes from nuclear power plants, but no new plants have been ordered since 1978. This paper reports that the problems that stand in the way of further development have to do with complexity and perceived risk. Licensing, construction management, and waste disposal are complex matters, and the possibility of accident has alienated a significant portion of the public. But a national poll conducted by Bruskin/Goldring at the beginning of February shows that opposition to nuclear energy is softening. Sixty percent of the American people support (strongly or moderately) the use of nuclear power, and 18 percent moderately oppose it. Only 15 percent remain obstinately opposed. Perhaps they are not aware of recent advances in reactor technology

Curing critical links in oscillator networks as power flow models

International Nuclear Information System (INIS)

Rohden, Martin; Meyer-Ortmanns, Hildegard; Witthaut, Dirk; Timme, Marc

2017-01-01

Modern societies crucially depend on the robust supply with electric energy so that blackouts of power grids can have far reaching consequences. Typically, large scale blackouts take place after a cascade of failures: the failure of a single infrastructure component, such as a critical transmission line, results in several subsequent failures that spread across large parts of the network. Improving the robustness of a network to prevent such secondary failures is thus key for assuring a reliable power supply. In this article we analyze the nonlocal rerouting of power flows after transmission line failures for a simplified AC power grid model and compare different strategies to improve network robustness. We identify critical links in the grid and compute alternative pathways to quantify the grid’s redundant capacity and to find bottlenecks along the pathways. Different strategies are developed and tested to increase transmission capacities to restore stability with respect to transmission line failures. We show that local and nonlocal strategies typically perform alike: one can equally well cure critical links by providing backup capacities locally or by extending the capacities of bottleneck links at remote locations. (paper)

Ensuring safe operation at the Loviisa nuclear power plant

International Nuclear Information System (INIS)

Regnell, B.

1985-01-01

Safe operation of a nuclear plant can be achieved only if the plant is designed according to stringent safety principles, if the construction and commissioning work meets high standards and finally if proper attention is paid to the safety aspects in all operational activities. Clearly formulated safety principles and standards are required for all these steps. In the early phases of the Loviisa project only a few IAEA codes of practice and safety guides were available. Their usefulness was, however, felt early, and valuable guidance was offered by them in formulating the quality assurance programme, for example. The paper describes the approach taken in order to achieve high operational safety at the first nuclear power station in Finland, the Loviisa plant. The involvement in the project of the plant owner, Imatran Voima Oy (IVO), was very large, the company serving as its own architect-engineer. Experience has shown that the thorough knowledge of the plant, down to the finest details, obtained by extensive participation in design, erection and commissioning of the plant, is invaluable in the actual operation of the plant. This manifests itself most clearly in the event of malfunctions and incidents or if modifications have to be undertaken. Many different activities affecting the operational safety can be identified: actual operation of the plant, including the creation and maintaining of technical specifications, procedures, instructions, documentation systems, etc.; maintenance, repair and modification work; in-service inspection and testing practices; component failure data collection and analysis; incident reporting, collection and evaluation systems; operator training; quality assurance programme; procedures and implementation; reviews of operational safety by an independent safety committee; and supervision by the safety authorities. In the paper, all these activities are described in some detail. (author)

Criticality of a 237Np sphere

International Nuclear Information System (INIS)

Sanchez, Rene; Loaiza, David; Kimpland, Robert; Hayes, David; Cappiello, Charlene; Chadwick, Mark

2006-01-01

For the past five years, scientists at Los Alamos National Laboratory have mounted an unprecedented effort to get a better estimate of the critical mass of 237 Np. To accomplish this task, a 6-kg neptunium sphere was recently cast at the Chemical and Metallurgy Research (CMR) facility, which is part of the Los Alamos National Laboratory. The neptunium sphere was clad with tungsten and nickel to reduce the dose rates from the 310 keV gamma rays from the first daughter of neptunium, namely, 233 Pa. 237 Np is a byproduct of power production in nuclear reactors. It is primarily produced by successive neutron captures in 235 U or through the (n,2n) reaction in 238 U. These nuclear reactions lead to the production of 237 U, which decays by beta emission into 237 Np, namely, 235 U(n,γ) 236 U, 236 U(n,γ) 237 U→β→ 237 Np, 238 U (n,2n) 237 U→β→ 237 Np. It is estimated that a typical 1000 MW(e) produces on the order of 12 to 13 kg of neptunium in a year. Some of this neptunium in irradiated fuel elements has been separated and is presently stored in containers in a liquid form. This method of storage is quite adequate because the fission cross section for 237 Np at thermal energies is quite low and any moderation of the neutron population by diluting the configurations with water would increase the critical mass to infinity. However, for long term storage, the neptunium liquid solutions must be converted into oxides and metals because these form are less movable and less likely to leak out of containers. Metals and oxides made out of neptunium have finite critical masses but there is a great uncertainty about these values because of the lack of experimental criticality data. Knowing precisely the critical mass of neptunium not only will help to validate mass storage limits or optimize storage configurations for safe disposition of these materials, but will also save thousands of dollars in transportation and disposition costs. The experimental results presented in

Curiosity's Autonomous Surface Safing Behavior Design

Science.gov (United States)

Neilson, Tracy A.; Manning, Robert M.

2013-01-01

The safing routines on all robotic deep-space vehicles are designed to put the vehicle in a power and thermally safe configuration, enabling communication with the mission operators on Earth. Achieving this goal is made a little more difficult on Curiosity because the power requirements for the core avionics and the telecommunication equipment exceed the capability of the single power source, the Multi-Mission Radioisotope Thermoelectric Generator. This drove the system design to create an operational mode, called "sleep mode", where the vehicle turns off most of the loads in order to charge the two Li-ion batteries. The system must keep the vehicle safe from over-heat and under-heat conditions, battery cell failures, under-voltage conditions, and clock failures, both while the computer is running and while the system is sleeping. The other goal of a safing routine is to communicate. On most spacecraft, this simply involves turning on the receiver and transmitter continuously. For Curiosity, Earth is above the horizon only a part of the day for direct communication to the Earth, and the orbiter overpass opportunities only occur a few times a day. The design must robustly place the Rover in a communicable condition at the correct time. This paper discusses Curiosity's autonomous safing behavior and describes how the vehicle remains power and thermally safe while sleeping, as well as a description of how the Rover communicates with the orbiters and Earth at specific times.

Calibration of RB reactor power; Kalibrisanje snage reaktora RB

Energy Technology Data Exchange (ETDEWEB)

Sotic, O; Markovic, H; Ninkovic, M; Strugar, P; Dimitrijevic, Z; Takac, S; Stefanovic, D; Kocic, A; Vranic, S [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

1976-09-15

The first and only calibration of RB reactor power was done in 1962, and the obtained calibration ratio was used irrespective of the lattice pitch and core configuration. Since the RB reactor is being prepared for operation at higher power levels it was indispensable to reexamine the calibration ratio, estimate its dependence on the lattice pitch, critical level of heavy water and thickness of the side reflector. It was necessary to verify the reliability of control and dosimetry instruments, and establish neutron and gamma dose dependence on reactor power. Two series of experiments were done in June 1976. First series was devoted to tests of control and dosimetry instrumentation and measurements of radiation in the RB reactor building dependent on reactor power. Second series covered measurement of thermal and epithermal neuron fluxes in the reactor core and calculation of reactor power. Four different reactor cores were chosen for these experiments. Reactor pitches were 8, 8{radical}2, and 16 cm with 40, 52 and 82 fuel channels containing 2% enriched fuel. Obtained results and analysis of these results are presented in this document with conclusions related to reactor safe operation.

A level III PSA for the inherently safe CAREM-25 nuclear power station

International Nuclear Information System (INIS)

Baron, Jorge H.; Nunez McLeod, J.; Rivera, S.S.

2000-01-01

A Level III PSA has been performed for the inherently safe CAREM-25 nuclear power station, as a requirement for licensing according to argentinian regulations. The CAREM-25 project is still at a detailed design state, therefore only internal events have been considered, and a representative site has been assumed for dose estimations. Several conservative hypothesis have been formulated, but even so an overall core melt frequency of 2.3E -5 per reactor year has been obtained. The risk estimations comply with the regulations. The risk values obtained are compared to the 700MW(e) nuclear power plant Atucha II PSA result, showing an effective risk reduction not only in the severe accident probability but alto in the consequence component of the risk estimation. (author)

Providing Nuclear Criticality Safety Analysis Education through Benchmark Experiment Evaluation

International Nuclear Information System (INIS)

Bess, John D.; Briggs, J. Blair; Nigg, David W.

2009-01-01

One of the challenges that today's new workforce of nuclear criticality safety engineers face is the opportunity to provide assessment of nuclear systems and establish safety guidelines without having received significant experience or hands-on training prior to graduation. Participation in the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and/or the International Reactor Physics Experiment Evaluation Project (IRPhEP) provides students and young professionals the opportunity to gain experience and enhance critical engineering skills.

47 CFR 73.6019 - Digital Class A TV station protection of low power TV, TV translator, digital low power TV and...

Science.gov (United States)

2010-10-01

... power TV, TV translator, digital low power TV and digital TV translator stations. 73.6019 Section 73... low power TV, TV translator, digital low power TV and digital TV translator stations. An application... A TV station will not be accepted if it fails to protect authorized low power TV, TV translator...

The United States Naval Nuclear Propulsion Program - Over 151 Million Miles Safely Steamed on Nuclear Power

Energy Technology Data Exchange (ETDEWEB)

None, None

2015-03-01

NNSA’s third mission pillar is supporting the U.S. Navy’s ability to protect and defend American interests across the globe. The Naval Reactors Program remains at the forefront of technological developments in naval nuclear propulsion and ensures a commanding edge in warfighting capabilities by advancing new technologies and improvements in naval reactor performance and reliability. In 2015, the Naval Nuclear Propulsion Program pioneered advances in nuclear reactor and warship design – such as increasing reactor lifetimes, improving submarine operational effectiveness, and reducing propulsion plant crewing. The Naval Reactors Program continued its record of operational excellence by providing the technical expertise required to resolve emergent issues in the Nation’s nuclear-powered fleet, enabling the Fleet to safely steam more than two million miles. Naval Reactors safely maintains, operates, and oversees the reactors on the Navy’s 82 nuclear-powered warships, constituting more than 45 percent of the Navy’s major combatants.

Full scale reactor safety experiments performed in the Marviken Power Station Sweden

International Nuclear Information System (INIS)

Thoren, H.G.; Ericson, L.

1977-01-01

Since 1972 experiments oriented towards increasing the understanding of reactor safety processes have been performed at the Marviken Power Station. This was originally built as a direct cycle BHWR but was never taken into nuclear operation. In addition to Sweden, the countries represented in these experiments are Denmark, the Federal Republic of Germany, Finland, Norway, the United States, the Netherlands, France and Japan. The first series of sixteen experiments included studies of the response of the PS-containment to simulated ruptures in the pipe systems that are connected to the pressure vessel. These tests were completed in 1973 and also included experimental studies of iodine transport, containment leakage, the behaviour of auxiliary components under accident conditions and pressure fluctuations in the wetwell water pool. One of the more essential findings of the tests was that the containment performance was in accordance with the pre-test calculations. A second series of eight blowdown tests was begun in February 1976. The main purpose of these tests is to provide additional information as to the characteristics of the pressure oscillations inside the containment and primarily in the wetwell water pool under different conditions. These oscillations were observed in the first series of blowdowns but only low frequencies could then be detected due to limitations in the measurement system. The measurement system was therefore substantially extended for this second series of experiments. A summary of the results from these two sets of blowdown tests are given in the paper. In 1976 preparations for a new test program were initiated. The objective of these tests is to improve the understanding of critical flow in the low quality and subcooled flow regions through short length, large diameter pipes. Extensive modifications of the test facility will be necessary in order to allow a discharge flow through openings which are up to 500 mm in diameter. Advanced plans

Nuclear power experience

International Nuclear Information System (INIS)

Daglish, J.

1982-01-01

A report is given of a recent international conference convened by the IAEA to consider the technical and economic experience acquired by the nuclear industry during the past 30 years. Quotations are given from a number of contributors. Most authors shared the opinion that nuclear power should play a major role in meeting future energy needs and it was considered that the conference had contributed to make nuclear power more viable. (U.K.)

Low-power laser therapy for carpal tunnel syndrome: effective optical power

Directory of Open Access Journals (Sweden)

Yan Chen

2016-01-01

Full Text Available Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efficacy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efficacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective optical power of low-power laser therapy for carpal tunnel syndrome. By monitoring the backside reflection and scattering laser power from human skin at the wrist, the effective laser power can be inferred. Using clinical measurements from 30 cases, we found that the effective laser power differed significantly among cases, with the measured laser reflection coefficient ranging from 1.8% to 54%. The reflection coefficient for 36.7% of these 30 cases was in the range of 10–20%, but for 16.7% of cases, it was higher than 40%. Consequently, monitoring the effective optical power during laser irradiation is necessary for the laser therapy of carpal tunnel syndrome.

Fire protection of safe shutdown capability at commercial nuclear power plants

International Nuclear Information System (INIS)

Sullivan, K.

1993-01-01

The comprehensive industrial safety standards and codes that exist today have evolved from lessons learned through past experience, research results, and improvements in technological capabilities. The current requirements for fire safety features of commercial nuclear power stations operated in the U.S. are a notable example of this practice. Although fire protection has always been an important design requirement, from the aftermath of a serious fire that occurred in 1975 at the Browns Ferry plant, it was learned that the life safety and property protection concerns of the major fire insurance underwriters may not sufficiently encompass nuclear safety issues, particularly with regard to the potential for fire damage to result in the common mode failure of redundant trains of systems, and composites important to the safe shutdown of the reactor. Following its investigations into the Browns Ferry fire, the Nuclear Regulatory Commission (NRC) promulgated guidance documents, which ultimately developed into mandatory regulations, necessary to assure the implementation of a fire protection program that would address nuclear safety concerns. The new criteria that evolved, contain prescriptive design features, as well as personnel and administrative requirements the Commission determined to be necessary to provide a defense-in-depth level of protection against the hazards of fire and its associated effects on safety related equipment. These criteria are primarily contained in Appendix R of Title 10 to the Code of Federal Regulations (10 CFR 50)

Design for High Performance, Low Power, and Reliable 3D Integrated Circuits

CERN Document Server

Lim, Sung Kyu

2013-01-01

This book describes the design of through-silicon-via (TSV) based three-dimensional integrated circuits.  It includes details of numerous “manufacturing-ready” GDSII-level layouts of TSV-based 3D ICs, developed with tools covered in the book. Readers will benefit from the sign-off level analysis of timing, power, signal integrity, and thermo-mechanical reliability for 3D IC designs.  Coverage also includes various design-for-manufacturability (DFM), design-for-reliability (DFR), and design-for-testability (DFT) techniques that are considered critical to the 3D IC design process. Describes design issues and solutions for high performance and low power 3D ICs, such as the pros/cons of regular and irregular placement of TSVs, Steiner routing, buffer insertion, low power 3D clock routing, power delivery network design and clock design for pre-bond testability. Discusses topics in design-for-electrical-reliability for 3D ICs, such as TSV-to-TSV coupling, current crowding at the wire-to-TSV junction and the e...

Fast critical experiments in FCA and their analysis

International Nuclear Information System (INIS)

Hirota, Jitsuya

1984-02-01

JAERI Fast Critical Facility FCA went critical for the first time in April, 1967. Since then, critical experiments and their analysis were carried out on thirty-five assemblies until march, 1982. This report summarizes many achievements obtained in these fifteen years and points out disagreements observed between the calculation and experiment for further studies. A series of mock-up experiments for Experimental Fast Reactor JOYO, a theoretical and numerical study of adjustment of group constants by using integral data and a development of proton-recoil counter system for fast neutron spectrum measurement won high praise. Studies of Doppler effect of structural materials, effect of fission product accumulation on sodium-void worth, axially heterogeneous core and actinide cross sections attracted world-side attention. Significant contributions were also made to Prototype Fast Breeder Reactor MONJU through the partial mock-up experiments. Disagreements between the calculation and experiment were observed in the following items; reaction rate distribution and reactivity worth of B 4 C absorber in radial blanket, central reactivity worth in core with reflector, plate/pin fuel heterogeneity effect on criticality, sodium-void effect in central core region, Doppler effect of structural materials, core neutron spectrum near large resonances of iron and oxygen, effect of fission product accumulation on sodium-void worth, physics property of heterogeneous core, reactivity change resulted from fuel slumping and so on. Further efforts should be made to solve these disagreements through recalculating the experimental results with newly developed data and methods and carrying out the experiments intended to identify the cause of disagreement. (author)

Research and design calculation of multipurpose critical assembly using moderated light water and low enriched fuel from 1.6 to 5.0% U-235

International Nuclear Information System (INIS)

Nguyen Kien Cuong; Vo Doan Hai Dang; Luong Ba Vien; Le Vinh Vinh; Huynh Ton Nghiem; Nguyen Minh Tuan; Nguyen Manh Hung; Pham Quang Huy; Tran Quoc Duong; Tran Tri Vien

2015-01-01

Basing on the idea in ??using fuel of nuclear power plants such as PWR (AP-1000) and VVER-1000 with light water as moderation, design calculation of critical assembly was performed to confirm the possibility of using these fuels. Designed critical assembly has simple structure consisting of low enriched fuel from 1.6% to 5% U-235; water has functions as cooling, biological protection and control. Critical assembly is operated at nominal power 100 W with fuel pitch about 2.0 cm. Applications of the critical assembly are quite abundant in basic research, education and training with low investment cost compare with research reactor and easy in operation. So critical assembly can be used for university or training centre for nuclear engineering training. Main objectives of the project are: design calculation in neutronics, thermal hydraulics and safety analysis for critical configuration benchmarks using low enriched fuel; design in mechanical and auxiliary systems for critical assembly; determine technical specifications and estimate construction, installation cost of critical assembly. The process of design, fabrication, installation and construction of critical assembly will be considered with different implementation phases and localization capabilities in installation of critical assembly is highly feasibility. Cost estimation of construction and installation of critical assembly was implemented and showed that investment cost for critical assembly is much lower than research reactor and most of components, systems of critical assembly can be localized with current technique quality of the country. (author)

Work and power fluctuations in a critical heat engine

Science.gov (United States)

Holubec, Viktor; Ryabov, Artem

2017-09-01

We investigate fluctuations of output work for a class of Stirling heat engines with working fluid composed of interacting units and compare these fluctuations to an average work output. In particular, we focus on engine performance close to a critical point where Carnot's efficiency may be attained at a finite power as reported by M. Campisi and R. Fazio [Nat. Commun. 7, 11895 (2016), 10.1038/ncomms11895]. We show that the variance of work output per cycle scales with the same critical exponent as the heat capacity of the working fluid. As a consequence, the relative work fluctuation diverges unless the output work obeys a rather strict scaling condition, which would be very hard to fulfill in practice. Even under this condition, the fluctuations of work and power do not vanish in the infinite system size limit. Large fluctuations of output work thus constitute inseparable and dominant element in performance of the macroscopic heat engines close to a critical point.

Work and power fluctuations in a critical heat engine.

Science.gov (United States)

Holubec, Viktor; Ryabov, Artem

2017-09-01

We investigate fluctuations of output work for a class of Stirling heat engines with working fluid composed of interacting units and compare these fluctuations to an average work output. In particular, we focus on engine performance close to a critical point where Carnot's efficiency may be attained at a finite power as reported by M. Campisi and R. Fazio [Nat. Commun. 7, 11895 (2016)2041-172310.1038/ncomms11895]. We show that the variance of work output per cycle scales with the same critical exponent as the heat capacity of the working fluid. As a consequence, the relative work fluctuation diverges unless the output work obeys a rather strict scaling condition, which would be very hard to fulfill in practice. Even under this condition, the fluctuations of work and power do not vanish in the infinite system size limit. Large fluctuations of output work thus constitute inseparable and dominant element in performance of the macroscopic heat engines close to a critical point.

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)

Introduction to 'International Handbook of Criticality Safety Benchmark Experiments'

International Nuclear Information System (INIS)

Komuro, Yuichi

1998-01-01

The Criticality Safety Benchmark Evaluation Project (CSBEP) was initiated in 1992 by the United States Department of Energy. The project quickly became an international effort as scientists from other interested countries became involved. The International Criticality Safety Benchmark Evaluation Project (ICSBEP) is now an official activity of the Organization for Economic Cooperation and Development-Nuclear Energy Agency (OECD-NEA). 'International Handbook of Criticality Safety Benchmark Experiments' was prepared and is updated year by year by the working group of the project. This handbook contains criticality safety benchmark specifications that have been derived from experiments that were performed at various nuclear critical facilities around the world. The benchmark specifications are intended for use by criticality safety engineers to validate calculation techniques used. The author briefly introduces the informative handbook and would like to encourage Japanese engineers who are in charge of nuclear criticality safety to use the handbook. (author)

Low field critical currents and ac losses of thin film niobium--tin superconductors

International Nuclear Information System (INIS)

Howard, R.E.

1977-01-01

The results of a study of the low field critical current and ac loss properties of niobium-tin thin films and layered composites fabricated by electron-beam coevaporation are presented. Particular emphasis is placed upon determining the suitability of this material for use as a conductor in a superconducting power transmission line. Chapter I contains a summary of this work and its major results together with an introduction to the scientific and engineering concepts associated with a superconducting power transmission line. Chapter II is a discussion of the physics of current transport and the associated loss mechanisms in a type-II superconductor. Chapter III gives the details of the electron-beam coevaporation technique developed to fabricate the samples for this study. Also discussed in this chapter are the effects of the evaporation conditions on the growth morphology of the niobium-tin films. Chapter IV presents the details of the experimental techniques developed to measure the ac loss and critical current in these samples as a function of temperature. Chapter V shows the dependence of the critical current of these films and composites on temperature, magnetic field, and on the number of artificially introduced pinning centers in the layered composites. Experimental results are also presented concerning the stability of these conductors against flux jumps. Chapter VI is a discussion of the ac losses in these samples. Detailed comparisons are made between the measured loss and the predictions of the critical state model

Experiments of JRR-4 low-enriched-uranium-silicied fuel core

International Nuclear Information System (INIS)

Hirane, Nobuhiko; Ishikuro, Yasuhiro; Nagadomi, Hideki; Yokoo, Kenji; Horiguchi, Hironori; Nemoto, Takumi; Yamamoto, Kazuyoshi; Yagi, Masahiro; Arai, Nobuyoshi; Watanabe, Shukichi; Kashima, Yoichi

2006-03-01

JRR-4, a light-water-moderated and cooled, swimming pool type research reactor using high-enriched uranium plate-type fuels had been operated from 1965 to 1996. In order to convert to low-enriched-uranium-silicied fuels, modification work had been carried out for 2 years, from 1996 to 1998. After the modification, start-up experiments were carried out to obtain characteristics of the low-enriched-uranium-silicied fuel core. The measured excess reactivity, reactor shutdown margin and the maximum reactivity addition rate satisfied the nuclear limitation of the safety report for licensing. It was confirmed that conversion to low-enriched-uranium-silicied fuels was carried out properly. Besides, the necessary data for reactor operation were obtained, such as nuclear, thermal hydraulic and reactor control characteristics. This report describes the results of start-up experiments and burnup experiments. The first criticality of low-enriched-uranium-silicied core was achieved on 14th July 1998, and the operation for joint-use has been carried out since 6th October 1998. (author)

Critical heat flux in subcooled and low quality boiling

International Nuclear Information System (INIS)

Maroti, L.

1976-06-01

A semi-empirical relationship for critical heat flux prediction in a light water cooled power reactor core is developed. The method of developing this relationship is the extension of the analysis of pool boiling crisis for forced convective boiling. In the calculations the energy conservation equation is used together with additional condition for the crisis. Assuming that in the vicinity of the crisis the heat is transported only by the latent heat of the vapour this condition for the crisis can be characterized by the maximum departure velocity of the vapour. Because only flow boiling crisis associating with bubbling at the heating surface is considered the model could be applied only for low quality boiling crisis. The calculated results are compared to the available experimental ones. (Sz.N.Z.)

Experience in the use of systematic approach to training (SAT) for nuclear power plant personnel

International Nuclear Information System (INIS)

1998-12-01

One of the essential requirements for safe and reliable nuclear power plant operation and maintenance is the availability of competent personnel, and thus systematic approach to training (SAT) is recognized world-wide. Many countries have applied and implemented the use of SAT in their training systems as demonstrated by the results of the IAEA World Survey on Nuclear Power Plant Personnel Training. This report complements two IAEA publications, the Guidebook on Nuclear Power Plant Personnel and its Evaluation (Technical Reports Series No. 380) and the IAEA World Survey of Nuclear Power Plant Personnel Training (IAEA-TECDOC-1063). It provides a detailed overview and analysis of the experience gained worldwide on the introduction and application of SAT, including the reasons why SAT was introduced and lessons learned. The technical document will be of use for nuclear power plant managers and supervisors and all those responsible for training of personnel. The report was initiated by the International Working Group at a Technical Committee Meeting. Experiences gained from the application of SAT in the following Member States are included: Armenia, Bulgaria, Canada, China, Czech Republic, Finland, France, Germany, Hungary, India, Kazakhstan, Lithuania, Mexico, Romania, Russian Federation, Slovenia, Slovakia, Spain, Sweden, Ukraine, United Kingdom and United States of America

Experience in the use of systematic approach to training (SAT) for nuclear power plant personnel

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-12-01

One of the essential requirements for safe and reliable nuclear power plant operation and maintenance is the availability of competent personnel, and thus systematic approach to training (SAT) is recognized world-wide. Many countries have applied and implemented the use of SAT in their training systems as demonstrated by the results of the IAEA World Survey on Nuclear Power Plant Personnel Training. This report complements two IAEA publications, the Guidebook on Nuclear Power Plant Personnel and its Evaluation (Technical Reports Series No. 380) and the IAEA World Survey of Nuclear Power Plant Personnel Training (IAEA-TECDOC-1063). It provides a detailed overview and analysis of the experience gained worldwide on the introduction and application of SAT, including the reasons why SAT was introduced and lessons learned. The technical document will be of use for nuclear power plant managers and supervisors and all those responsible for training of personnel. The report was initiated by the International Working Group at a Technical Committee Meeting. Experiences gained from the application of SAT in the following Member States are included: Armenia, Bulgaria, Canada, China, Czech Republic, Finland, France, Germany, Hungary, India, Kazakhstan, Lithuania, Mexico, Romania, Russian Federation, Slovenia, Slovakia, Spain, Sweden, Ukraine, United Kingdom and United States of America. Refs, figs, tabs

Low grade waste heat recovery using heat pumps and power cycles

International Nuclear Information System (INIS)

Bor, D.M. van de; Infante Ferreira, C.A.; Kiss, Anton A.

2015-01-01

Thermal energy represents a large part of the global energy usage and about 43% of this energy is used for industrial applications. Large amounts are lost via exhaust gases, liquid streams and cooling water while the share of low temperature waste heat is the largest. Heat pumps upgrading waste heat to process heat and cooling and power cycles converting waste heat to electricity can make a strong impact in the related industries. The potential of several alternative technologies, either for the upgrading of low temperature waste heat such as compression-resorption, vapor compression and trans-critical heat pumps, or for the conversion of this waste heat by using organic Rankine, Kalina and trilateral cycle engines, are investigated with regards to energetic and economic performance by making use of thermodynamic models. This study focuses on temperature levels of 45–60 °C as at this temperature range large amounts of heat are rejected to the environment but also investigates the temperature levels for which power cycles become competitive. The heat pumps deliver 2.5–11 times more energy value than the power cycles in this low temperature range at equal waste heat input. Heat engines become competitive with heat pumps at waste heat temperatures at 100 °C and above. - Highlights: • Application of heat pump technology for heating and cooling. • Compression resorption heat pumps operating with large glides approaching 100 K. • Compression-resorption heat pumps with wet compression. • Potential to convert Industrial waste heat to power or high grade heat. • Comparison between low temperature power cycles and heat pumps

Low power consumption mini rotary actuator with SMA wires

Science.gov (United States)

Manfredi, Luigi; Huan, Yu; Cuschieri, Alfred

2017-11-01

Shape memory alloys (SMAs) are smart materials widely used as actuators for their high power to weight ratio despite their well-known low energy efficiency and limited mechanical bandwidth. For robotic applications, SMAs exhibit limitations due to high power consumption and limited stroke, varying from 4% to 7% of the total length. Hysteresis, during the contraction and extension cycle, requires a complex control algorithm. On the positive side, the small size and low weight are eminently suited for the design of mini actuators for robotic platforms. This paper describes the design and construction of a light weight and low power consuming mini rotary actuator with on-board contact-less position and force sensors. The design is specifically intended to reduce (i) energy consumption, (ii) dimensions of the sensory system, and (iii) provide a simple control without any need for SMA characterisation. The torque produced is controlled by on-board force sensors. Experiments were performed to investigate the energy consumption and performance (step and sinusoidal angle profiles with a frequency varying from 0.5 to 10 Hz and maximal amplitude of {15}\\circ ). We describe a transient capacitor effect related to the SMA wires during the sinusoidal profile when the active SMA wire is powered and the antagonist one switched-off, resulting in a transient current time varying from 300 to 400 ms.

Is "Safety" Dangerous? A Critical Examination of the Classroom as Safe Space

Directory of Open Access Journals (Sweden)

Betty J. Barrett

2010-06-01

Full Text Available The notion that the classroom can, indeed must, be a safe space to promote student engagement and enhance academic outcomes is pervasive in the teaching and learning literature. Despite the prevalence of this claim, there is a dearth of empirical evidence documenting the effectiveness of safe space classrooms in achieving these goals. The purpose of this essay is to provide a critical examination of the classroom as safe space. I begin by deconstructing the common meanings of safety as presented in the pedagogical literature and provide an overview of the existing research on student perceptions of safe space learning environments. I then problematize the metaphor of the classroom as safe space through an examination of 1 the impact of safety on student intellectual development 2 the impossibility of safety for students in marginalized and oppressed populations 3 the challenges to assessing student learning in safe environments and 4 the ambiguity inherent in defining safety for students. I conclude by arguing that both educators and students are better served by the development of an alternative discourse of classroom safety, one that is predicated on the notion of classroom civility.Dans la littérature sur l’enseignement et l’apprentissage, la notion selon laquelle la classe doit vraiment être un espace sécuritaire pour promouvoir la participation de l’étudiant et améliorer ses résultats scolaires est omniprésente. Malgré la prévalence de cette affirmation, il y a une pénurie de données probantes empiriques venant étayer l’efficacité des classes en tant qu’espace sécuritaire afin d’atteindre ces buts. L’objectif du présent essai est de procéder à un examen critique de la classe en tant qu’espace sécuritaire. Je commence par déconstruire la signification courante de la sécurité telle qu���elle est présentée dans la littérature sur la pédagogie et fournis un aperçu de la

The sound power emitted by a source of low acoustic impedance

DEFF Research Database (Denmark)

Jacobsen, Finn; Verholt, Lars M.

1998-01-01

Several authors have maintained that a source of low acoustic impedance (which includes standardised reference sources of the aerodynamic type) would radiate less than the free field power in a reverberation room. However, neither computer simulations nor experiments have confirmed this assertion....

Flight Testing a Real-Time Hazard Detection System for Safe Lunar Landing on the Rocket-Powered Morpheus Vehicle

Science.gov (United States)

Trawny, Nikolas; Huertas, Andres; Luna, Michael E.; Villalpando, Carlos Y.; Martin, Keith E.; Carson, John M.; Johnson, Andrew E.; Restrepo, Carolina; Roback, Vincent E.

2015-01-01

The Hazard Detection System (HDS) is a component of the ALHAT (Autonomous Landing and Hazard Avoidance Technology) sensor suite, which together provide a lander Guidance, Navigation and Control (GN&C) system with the relevant measurements necessary to enable safe precision landing under any lighting conditions. The HDS consists of a stand-alone compute element (CE), an Inertial Measurement Unit (IMU), and a gimbaled flash LIDAR sensor that are used, in real-time, to generate a Digital Elevation Map (DEM) of the landing terrain, detect candidate safe landing sites for the vehicle through Hazard Detection (HD), and generate hazard-relative navigation (HRN) measurements used for safe precision landing. Following an extensive ground and helicopter test campaign, ALHAT was integrated onto the Morpheus rocket-powered terrestrial test vehicle in March 2014. Morpheus and ALHAT then performed five successful free flights at the simulated lunar hazard field constructed at the Shuttle Landing Facility (SLF) at Kennedy Space Center, for the first time testing the full system on a lunar-like approach geometry in a relevant dynamic environment. During these flights, the HDS successfully generated DEMs, correctly identified safe landing sites and provided HRN measurements to the vehicle, marking the first autonomous landing of a NASA rocket-powered vehicle in hazardous terrain. This paper provides a brief overview of the HDS architecture and describes its in-flight performance.

Boiling transition phenomenon in BWR fuel assemblies effect of fuel spacer shape on critical power

International Nuclear Information System (INIS)

Yamamoto, Yasushi; Morooka, Shin-ichi; Mitsutake, Toru; Yokobori, Seiichi; Kimura, Jiro.

1996-01-01

A thorough understanding of the thermal-hydraulic phenomena near fuel spacer is necessary for the accurate prediction of the critical power of BWR fuel assemblies, and is thus essential for effective developments of a new BWR fuel assembly. The main purpose of this study is to develop an accurate method for predicting the effect of spacer shapes on critical power. Tests have been conducted under actual BWR operating conditions, using an annulus flow channel consisting of a heated rod and circular-tube channel, and BWR simulated 4x4 rod bundles with heater rods unheated just upsteam of spacer. The effect of spacer shapes on critical power was predicted analytically based on the droplet deposition rate estimation. The droplet deposition rate for different spacer shapes was calculated using a single-phase flow model. The prediction results were compared with the test results for the annulus flow channel using ring-type spacers. Analytical results of critical power agreed with measured critical power from point of the effects of changes in the rod-spacer clearance and the spacer thickness on critical power. (author)

Critical review of the first-law efficiency in different power combined cycle architectures

International Nuclear Information System (INIS)

Iglesias Garcia, Steven; Ferreiro Garcia, Ramon; Carbia Carril, Jose; Iglesias Garcia, Denis

2017-01-01

Highlights: • The adiabatic expansion based TC can improve the energy efficiency of CCs. • A revolutionary TC can be a starting point to develop high-performance CCs. • A theoretical thermal efficiency of 83.7% was reached in a Nuclear Power Plant using a TC as bottoming cycle. - Abstract: This critical review explores the potential of an innovative trilateral thermodynamic cycle used to transform low-grade heat into mechanical work and compares its performance with relevant traditional thermodynamic cycles in combined cycles. The aim of this work is to show that combined cycles use traditional low efficiency power cycles in their bottoming cycle, and to evaluate theoretically the implementation of alternative power bottoming cycles. Different types of combined cycles have been reviewed, highlighting their relevant characteristics. The efficiencies of power plants using combined cycles are reviewed and compared. The relevance of researching thermodynamic cycles for combined cycle applications is that a vast amount of heat energy is available at negligible cost in the bottoming cycle of a combined cycle, with the drawback that existing thermal cycles cannot make efficient use of such available low temperature heat due to their low efficiency. The first-law efficiency is used as a parameter to compare and suggest improvements in the combined cycles (CCs) reviewed. The analysis shows that trilateral cycles using closed processes are by far the most efficient published thermal cycles for combined cycles to transform low-grade heat into mechanical work. An innovative trilateral bottoming cycle is proposed to show that the application of non-traditional power cycles can increase significantly the first-law efficiency of CCs. The highest first-law efficiencies achieved are: 85.55% in a CC using LNG cool, 73.82% for a transport vehicle CC, 74.40% in a marine CC, 83.07% in a CC for nuclear power plants, 73.82% in a CC using Brayton and Rankine cycles, 78.31% in a CC

The Analysis of SBWR Critical Power Bundle Using Cobrag Code

Directory of Open Access Journals (Sweden)

Yohannes Sardjono

2013-03-01

Full Text Available The coolant mechanism of SBWR is similar with the Dodewaard Nuclear Power Plant (NPP in the Netherlands that first went critical in 1968. The similarity of both NPP is cooled by natural convection system. These coolant concept is very related with same parameters on fuel bundle design especially fuel bundle length, core pressure drop and core flow rate as well as critical power bundle. The analysis was carried out by using COBRAG computer code. COBRAG computer code is GE Company proprietary. Basically COBRAG computer code is a tool to solve compressible three-dimensional, two fluid, three field equations for two phase flow. The three fields are the vapor field, the continuous liquid field, and the liquid drop field. This code has been applied to analyses model flow and heat transfer within the reactor core. This volume describes the finitevolume equations and the numerical solution methods used to solve these equations. This analysis of same parameters has been done i.e.; inlet sub cooling 20 BTU/lbm and 40 BTU/lbm, 1000 psi pressure and R-factor is 1.038, mass flux are 0.5 Mlb/hr.ft2, 0.75 Mlb/hr.ft2, 1.00 Mlb/hr.ft2 and 1.25 Mlb/hr.ft2. Those conditions based on history operation of some type of the cell fuel bundle line at GE Nuclear Energy. According to the results, it can be concluded that SBWR critical power bundle is 10.5 % less than current BWR critical power bundle with length reduction of 12 ft to 9 ft.

Low-Power, Low-Voltage Analog to Digital ΣΔ

DEFF Research Database (Denmark)

Wismar, Ulrik Sørensen

2007-01-01

, and since long operation time is required, low supply voltage and low power consumption are of paramount importance. Consequently, various topologies have been compared to nd the most power ecient audio frequency modulator topology. Chapter 4 of this thesis compares power consumption of two of the most...... prevalent topologies, the single-loop modulator with integration in discrete time and the single-loop modulator with integration in continuous time. Both modulator topologies are with feedback, and all intermediate signals are in the voltage mode. Chapter 5 treats a modulator without feedback. Another...

Characterization and design of a low-power wireless power delivery system

Science.gov (United States)

Falkenstein, Erez Avigdor

There is an increased demand for wireless sensors for data gathering and transmission where running wires to power a device or changing/charging batteries is difficult. Often the data is gathered at locations that are difficult to access, that need to be covert, and/or where the sensors cannot be easily maintained. Some examples are implanted sensors for medical diagnostics and therapy, structural monitoring sensors, sensors inside hazardous manufacturing or other hazardous environments, etc. For any low power sensor that operates at a low duty cycle, and in an environment with low levels of light or vibration, RF wireless powering offers the potential for maintenance-free operation. The thesis focuses on a design methodology for low-power non-directional far-field wireless powering. The power receiver consists of one or more antennae which receive plane waves transmitted by the powering source, and deliver the RF power to a rectifying element. The resulting DC power is optimally transferred to the electronic application via a power management circuit. The powering is independent of the electronic application which can include wireless transmission of sensor data. The design and implementation of an integrated rectifier-antenna at low incident power densities (from 25--200 muW/cm2) is presented. Nonlinear source-pull measurements and harmonic balance simulations are used for finding the optimal rectifying device RF and DC impedances for efficient rectification. Experimental results show that an antenna design with a specific complex impedance reaches the highest rectification efficiency. Several examples of the design methodology will be shown. In specific, characterization of a rectifying patch antenna at frequency of 2.45GHz will be detailed, with an optimal RF impedance of 137+j149O and an optimal DC load of 365O resulting in RF to DC conversion efficiency of 63% for the rectifier alone and 56% for the total rectifying antenna.

Operating experience and performance at Narora Atomic Power Station

International Nuclear Information System (INIS)

Mittal, Subhash; Gupta, J.P.

1998-01-01

Narora Atomic Power Station consists of two units of 220 MWe capacity each. These are Pressurized Heavy Water Reactors, fuelled by natural uranium, moderated and cooled by heavy water. The Station is owned by Nuclear Power Corporation of India Ltd., which is responsible for design, construction, commissioning, and operation of all nuclear power stations in the country. NAPS was the first opportunity to apply operating experiences in design, keeping in view the evolving safety and seismicity requirements, ease of maintenance, inservice inspection needs, improved construction ability and standardization. Both the units of NAPS are having improved safety standards of current international levels. All the equipment are indigenous with improved quality and reliability. The first unit of the station went critical in March 1989 and synchronized to the grid in July 1989. The second units followed with its criticality in October 1991 and synchronization in January 1992. Considering the initial stabilizing period, the performance of both units of NAPS has progressively improved over the years. The annual capacity factor for NAPS - 1 was 90.01% and for NAPS - 2 was 89.01% for the financial year 1997-1998. This paper presents an analysis of the performance during the last three years and measures taken to improve it. The stated enhanced performance could be achieved by improvement in human performance by training/re-training, scrupulous monitoring and review of equipment/systems, institution of adequate procedure and ensuring their adherence. (authors)

A video wireless capsule endoscopy system powered wirelessly: design, analysis and experiment

International Nuclear Information System (INIS)

Pan, Guobing; Chen, Jiaoliao; Xin, Wenhui; Yan, Guozheng

2011-01-01

Wireless capsule endoscopy (WCE), as a relatively new technology, has brought about a revolution in the diagnosis of gastrointestinal (GI) tract diseases. However, the existing WCE systems are not widely applied in clinic because of the low frame rate and low image resolution. A video WCE system based on a wireless power supply is developed in this paper. This WCE system consists of a video capsule endoscope (CE), a wireless power transmission device, a receiving box and an image processing station. Powered wirelessly, the video CE has the abilities of imaging the GI tract and transmitting the images wirelessly at a frame rate of 30 frames per second (f/s). A mathematical prototype was built to analyze the power transmission system, and some experiments were performed to test the capability of energy transferring. The results showed that the wireless electric power supply system had the ability to transfer more than 136 mW power, which was enough for the working of a video CE. In in vitro experiments, the video CE produced clear images of the small intestine of a pig with the resolution of 320 × 240, and transmitted NTSC format video outside the body. Because of the wireless power supply, the video WCE system with high frame rate and high resolution becomes feasible, and provides a novel solution for the diagnosis of the GI tract in clinic

Critical Clearing Time and Wind Power in Small Isolated Power Systems Considering Inertia Emulation

Directory of Open Access Journals (Sweden)

Elías Jesús Medina-Domínguez

2015-11-01

Full Text Available The stability and security of small and isolated power systems can be compromised when large amounts of wind power enter them. Wind power integration depends on such factors as power generation capacity, conventional generation technology or grid topology. Another issue that can be considered is critical clearing time (CCT. In this paper, wind power and CCT are studied in a small isolated power system. Two types of wind turbines are considered: a squirrel cage induction generator (SCIG and a full converter. Moreover, the full converter wind turbine’s inertia emulation capability is considered, and its impact on CCT is discussed. Voltage is taken into account because of its importance in power systems of this kind. The study focuses on the small, isolated Lanzarote-Fuerteventura power system, which is expected to be in operation by 2020.

New signal acquisition and processing system for the execution of initial criticality after refueling and physical tests at low power in Angra-2, with the incorporation of the real time resolution of the inverse point kinetic equation - IPK

Energy Technology Data Exchange (ETDEWEB)

Júnior, Décio Brandes M.F.; Oliveira, Mônica Georgia N.; Silva, Cristiano da, E-mail: deciobr@eletronuclear.gov.br, E-mail: mongeor@eletronuclear.gov.br, E-mail: cdsilva@eletronuclear.gov.br [Eletrobrás Termonuclear S.A. (ELETRONUCLEAR), Angra dos Reis, RJ (Brazil). Departamento DDD.O - Física de Reatores

2017-07-01

The goal of this work is present the new System of Acquisition and Signal Processing for the execution of the initial criticality after refueling and physical tests at low power with the incorporation of the real time resolution of Inverse Point Kinetic Equations (IPK). The system was developed using cRIO 9082 hardware (compactRIO), which is a programmable logic controller (PLC) and, the National Lab's LabVIEW programming language. The developed system enabled a better visualization and monitoring interface of the neutron flux evolution during the first criticality of cycle and following the low power physical tests, which allows the Reactor Physics Group and Reactor Operators of Angra 2 guide faster and accurately the reactivity variations at physical tests. The digital reactivity meter developed reinforces in Angra-2 the set of operational practices of reactivity management. (author)

New signal acquisition and processing system for the execution of initial criticality after refueling and physical tests at low power in Angra-2, with the incorporation of the real time resolution of the inverse point kinetic equation - IPK

International Nuclear Information System (INIS)

Júnior, Décio Brandes M.F.; Oliveira, Mônica Georgia N.; Silva, Cristiano da

2017-01-01

The goal of this work is present the new System of Acquisition and Signal Processing for the execution of the initial criticality after refueling and physical tests at low power with the incorporation of the real time resolution of Inverse Point Kinetic Equations (IPK). The system was developed using cRIO 9082 hardware (compactRIO), which is a programmable logic controller (PLC) and, the National Lab's LabVIEW programming language. The developed system enabled a better visualization and monitoring interface of the neutron flux evolution during the first criticality of cycle and following the low power physical tests, which allows the Reactor Physics Group and Reactor Operators of Angra 2 guide faster and accurately the reactivity variations at physical tests. The digital reactivity meter developed reinforces in Angra-2 the set of operational practices of reactivity management. (author)

Detection of low caloric power of coal by pulse fast-thermal neutron analysis

International Nuclear Information System (INIS)

Gu De-shan; Sang Hai-feng; Qiao Shuang; Liu Yu-ren, Liu Lin-mao; Jing Shi-wei; Chinese Academy of Sciences, Changchun

2004-01-01

Analysis method and principle of pulse fast-thermal neutron analysis (PFTNA) are introduced. A system for the measurement of low caloric power of coal by PFTNA is also presented. The 14 MeV pulse neutron generator and BGO detector and 4096 MCA were applied in this system. A multiple linear regression method applied to the data solved the interferential problem of multiple elements. The error of low caloric power between chemical analysis and experiment was less than 0.4 MJ/kg. (author)

Nuclear power and low level radiation hazards

International Nuclear Information System (INIS)

Myers, D.K.; Newcombe, H.B.

1979-03-01

Even in the future, nuclear power is expected to contribute less than 1/10th of the present total population exposure to man-made radiation. By the best estimates available, the current health risks of nuclear power generation appear to be much less than those associated with the major alternative sources of energy, with the exception of natural gas which is about equally safe. Uncertainties concerning the radiation risks from nuclear power, from medical x-rays and from the effects of reduced ventillation to conserve heat appear to be less than those associated with estimates of risks from the use of coal and various other sources of energy. This is in part because of the large amount of effort devoted to studies of radiation effects. The benefits in terms of current life expectancy associated with any of the conventional or unconventional methods of power production appear to greatly outweigh the associated current health hazards. (author)

Monte Carlo analysis of the slightly enriched uranium-D2O critical experiment LTRIIA (AWBA Development Program)

International Nuclear Information System (INIS)

Hardy, J. Jr.; Shore, J.M.

1981-11-01

The Savannah River Laboratory LTRIIA slightly-enriched uranium-D 2 O critical experiment was analyzed with ENDF/B-IV data and the RCP01 Monte Carlo program, which modeled the entire assembly in explicit detail. The integral parameters delta 25 and delta 28 showed good agreement with experiment. However, calculated K/sub eff/ was 2 to 3% low, due primarily to an overprediction of U238 capture. This is consistent with results obtained in similar analyses of the H 2 O-moderated TRX critical experiments. In comparisons with the VIM and MCNP2 Monte Carlo programs, good agreement was observed for calculated reeaction rates in the B 2 =0 cell

Low-Power Amplifier-Discriminators for High Time Resolution Detection

CERN Document Server

Despeisse, M; Anghinolfi, F; Tiuraniemi, S; Osmic, F; Riedler, P; Kluge, A; Ceccucci, A

2009-01-01

Low-power amplifier-discriminators based on a so-called NINO architecture have been developed with high time resolution for the readout of radiation detectors. Two different circuits were integrated in the NINO13 chip, processed in IBM 130 nm CMOS technology. The LCO version (Low Capacitance and consumption Optimization) was designed for potential use as front-end electronics in the Gigatracker of the NA62 experiment at CERN. It was developed as pixel readout for solid-state pixel detectors to permit minimum ionizing particle detection with less than 180 ps rms resolution per pixel on the output pulse, for power consumption below 300 mu W per pixel. The HCO version (High Capacitance Optimization) was designed with 4 mW power consumption per channel to provide timing resolution below 20 ps rms on the output pulse, for charges above 10 fC. Results presented show the potential of the LCO and HCO circuits for the precise timing readout of solid-state detectors, vacuum tubes or gas detectors, for applications in h...

A RE-INTRODUCTION TO ANOMALIES OF CRITICALITY

International Nuclear Information System (INIS)

Puigh, R.J.

2009-01-01

In 1974, a small innocuous document was submitted to the American Nuclear Society's Criticality Safety Division for publication that would have lasting impacts on this nuclear field The author was Duane Clayton, manager of the Battelle Pacific Northwest National Laboratory's Critical Mass Lab, the world's preeminent reactor critical experimenter with plutonium solutions. The document was entitled, 'Anomalies of Criticality'. 'Anomalies...' was a compilation of more than thirty separate and distinct examples of departures from what might be commonly expected in the field of nuclear criticality. Mr. Clayton's publication was the derivative of more than ten thousand experiments and countless analytical studies conducted world-wide on every conceivable reactor system imaginable: from fissile bearing solutions to solids, blocks to arrays of fuel rods, low-enriched uranium oxide systems to pure plutonium and highly enriched uranium systems. After publication, the document was commonly used within the nuclear fuel cycle and reactor community to train potential criticality/reactor analysts, experimenters and fuel handlers on important things for consideration when designing systems with critically 'safe' parameters in mind The purpose of this paper is to re-introduce 'Anomalies of Criticality' to the current Criticality Safety community and to add new 'anomalies' to the existing compendium. By so doing, it is the authors' hope that a new generation of nuclear workers and criticality engineers will benefit from its content and might continue to build upon this work in support of the nuclear renaissance that is about to occur

Critical need for MFE: the Alcator DX advanced divertor test facility

Science.gov (United States)

Vieira, R.; Labombard, B.; Marmar, E.; Irby, J.; Wolf, S.; Bonoli, P.; Fiore, C.; Granetz, R.; Greenwald, M.; Hutchinson, I.; Hubbard, A.; Hughes, J.; Lin, Y.; Lipschultz, B.; Parker, R.; Porkolab, M.; Reinke, M.; Rice, J.; Shiraiwa, S.; Terry, J.; Theiler, C.; Wallace, G.; White, A.; Whyte, D.; Wukitch, S.

2013-10-01

Three critical challenges must be met before a steady-state, power-producing fusion reactor can be realized: how to (1) safely handle extreme plasma exhaust power, (2) completely suppress material erosion at divertor targets and (3) do this while maintaining a burning plasma core. Advanced divertors such as ``Super X'' and ``X-point target'' may allow a fully detached, low temperature plasma to be produced in the divertor while maintaining a hot boundary layer around a clean plasma core - a potential game-changer for magnetic fusion. No facility currently exists to test these ideas at the required parallel heat flux densities. Alcator DX will be a national facility, employing the high magnetic field technology of Alcator combined with high-power ICRH and LHCD to test advanced divertor concepts at FNSF/DEMO power exhaust densities and plasma pressures. Its extended vacuum vessel contains divertor cassettes with poloidal field coils for conventional, snowflake, super-X and X-point target geometries. Divertor and core plasma performance will be explored in regimes inaccessible in conventional devices. Reactor relevant ICRF and LH drivers will be developed, utilizing high-field side launch platforms for low PMI. Alcator DX will inform the conceptual development and accelerate the readiness-for-deployment of next-step fusion facilities.

Low-power wind plants

International Nuclear Information System (INIS)

Kovalenko, V.I.; Shevchenko, Yu.V.; Shikhajlov, N.A.; Kokhanevich, V.P.; Tanan, G.L.

1993-01-01

Design peculiarities, as well as the prospects of development and introduction of the low-power (from 0.5 up to 4 kW) wind power plants (WPP) are considered. The variants of WPP with vertical and horizontal rotation axis are described. The data characterizing cost and structure of expenditures on WPP manufacture and operation are given

Dry critical experiments and analyses performed in support of the Topaz-2 Safety Program

International Nuclear Information System (INIS)

Pelowitz, D.B.; Sapir, J.; Glushkov, E.S.; Ponomarev-Stepnoi, N.N.; Bubelev, V.G.; Kompanietz, G.B.; Krutov, A.M.; Polyakov, D.N.; Loynstev, V.A.

1994-01-01

In December 1991, the Strategic Defense Initiative Organization decided to investigate the possibility of launching a Russian Topaz-2 space nuclear power system. Functional safety requirements developed for the Topaz mission mandated that the reactor remain subcritical when flooded and immersed in water. Initial experiments and analyses performed in Russia and the United States indicated that the reactor could potentially become supercritical in several water- or sand-immersion scenarios. Consequently, a series of critical experiments was performed on the Narciss M-II facility at the Kurchatov Institute to measure the reactivity effects of water and sand immersion, to quantify the effectiveness of reactor modifications proposed to preclude criticality, and to benchmark the calculational methods and nuclear data used in the Topaz-2 safety analyses. In this paper we describe the Narciss M-II experimental configurations along with the associated calculational models and methods. We also present and compare the measured and calculated results for the dry experimental configurations

Dry critical experiments and analyses performed in support of the TOPAZ-2 safety program

International Nuclear Information System (INIS)

Pelowitz, D.B.; Sapir, J.; Glushkov, E.S.; Ponomarev-Stepnoi, N.N.; Bubelev, V.G.; Kompanietz, G.B.; Krutov, A.M.; Polyakov, D.N.; Lobynstev, V.A.

1995-01-01

In December 1991, the Strategic Defense Initiative Organization decided to investigate the possibility of launching a Russian Topaz-2 space nuclear power system. Functional safety requirements developed for the Topaz mission mandated that the reactor remain subcritical when flooded and immersed in water. Initial experiments and analyses performed in Russia and the United States indicated that the reactor could potentially become supercritical in several water- or sand-immersion scenarios. Consequently, a series of critical experiments was performed on the Narciss M-II facility at the Kurchatov Institute to measure the reactivity effects of water and sand immersion, to quantify the effectiveness of reactor modifications proposed to preclude criticality, and to benchmark the calculational methods and nuclear data used in the Topaz-2 safety analyses. In this paper we describe the Narciss M-II experimental configurations along with the associated calculational models and methods. We also present and compare the measured and calculated results for the dry experimental configurations. copyright 1995 American Institute of Physics

Experiences of ultra-low-crud high-nickel control in Onagawa nuclear power station

International Nuclear Information System (INIS)

Saito, M.; Goto, Y.; Shinomiya, T.; Sato, M.; Yamazaki, K.; Hirasawa, H.; Yotsuyanagi, T.

2002-01-01

We have adopted various countermeasures for worker dose reduction to plants in Onagawa Nuclear Power Station. ''Ni/Fe ratio control'' has been adopted to Unit 1, and ''ultra-low-crud high-nickel control'' has been adopted to Unit 2 and 3, along with other countermeasures like wide utilization of low Co materials, for the purpose of dose rate reduction of primary recirculation piping which is thought to be one of the main exposure sources. In this paper, we describe, first, the reason and background that ultra-low-crud high-nickel control has been adopted to Unit 2, and, second, water chemistry of Unit 2 up to the 5. cycle under ultra-low-crud high-nickel control compared to that of Unit 1 under Ni/Fe ratio control. Following those, we show brief analysis of the fuel crud of Unit 2 and water chemistry of Unit 3 only at the startup stage. (authors)

Workflow for Criticality Assessment Applied in Biopharmaceutical Process Validation Stage 1

Directory of Open Access Journals (Sweden)

Thomas Zahel

2017-10-01

Full Text Available Identification of critical process parameters that impact product quality is a central task during regulatory requested process validation. Commonly, this is done via design of experiments and identification of parameters significantly impacting product quality (rejection of the null hypothesis that the effect equals 0. However, parameters which show a large uncertainty and might result in an undesirable product quality limit critical to the product, may be missed. This might occur during the evaluation of experiments since residual/un-modelled variance in the experiments is larger than expected a priori. Estimation of such a risk is the task of the presented novel retrospective power analysis permutation test. This is evaluated using a data set for two unit operations established during characterization of a biopharmaceutical process in industry. The results show that, for one unit operation, the observed variance in the experiments is much larger than expected a priori, resulting in low power levels for all non-significant parameters. Moreover, we present a workflow of how to mitigate the risk associated with overlooked parameter effects. This enables a statistically sound identification of critical process parameters. The developed workflow will substantially support industry in delivering constant product quality, reduce process variance and increase patient safety.

Critical Experiments With Aqueous Solutions of 233UO2(NO3)2

International Nuclear Information System (INIS)

Thomas, J.T.

2001-01-01

This report provides the critical experimenter's interpretations and descriptions of informal critical experiment logbook notes and associated information (e.g., experimental equipment designs/sketches, chemical and isotopic analyses, etc.) for the purpose of formally documenting the results of critical experiments performed in the late 1960s at the Oak Ridge Critical Experiments Facility. The experiments were conducted with aqueous solutions of 97.6 wt % 233 U uranyl nitrate having uranium densities varying between about 346 g U/l and 45 g U/l. Criticality was achieved with single simple units (e.g., cylinders and spheres) and with spaced subcritical simple cylindrical units arranged in unreflected, water-reflected, and polyethylene reflected critical arrays

Review of the status of low power research reactors and considerations for its development

International Nuclear Information System (INIS)

Lim, In Cheol; Wu, Sang Ik; Lee, Byung Chul; Ha, Jae Joo

2012-01-01

At present, 232 research reactors in the world are in operation and two thirds of them have a power less than 1 MW. Many countries have used research reactors as the tools for educating and training students or engineers and for scientific service such as neutron activation analysis. As the introduction of a research reactor is considered a stepping stone for a nuclear power development program, many newcomers are considering having a low power research reactor. The IAEA has continued to provide forums for the exchange of information and experiences regarding low power research reactors. Considering these, the Agency is recently working on the preparation of a guide for the preparation of technical specification possibly for a member state to use when wanting to purchase a low power research reactor. In addition, ANS has stated that special consideration should be given to the continued national support to maintain and expand research and test reactor programs and to the efforts in identifying and addressing the future needs by working toward the development and deployment of next generation nuclear research and training facilities. Thus, more interest will be given to low power research reactors and its role as a facility for education and training. Considering these, the status of low power research reactors was reviewed, and some aspects to be considered in developing a low power research reactor were studied

Unmanned Aerial Systems Traffic Management (UTM): Safely Enabling UAS Operations in Low-Altitude Airspace

Science.gov (United States)

Rios, Joseph

2016-01-01

Currently, there is no established infrastructure to enable and safely manage the widespread use of low-altitude airspace and UAS flight operations. Given this, and understanding that the FAA faces a mandate to modernize the present air traffic management system through computer automation and significantly reduce the number of air traffic controllers by FY 2020, the FAA maintains that a comprehensive, yet fully automated UAS traffic management (UTM) system for low-altitude airspace is needed. The concept of UTM is to begin by leveraging concepts from the system of roads, lanes, stop signs, rules and lights that govern vehicles on the ground today. Building on its legacy of work in air traffic management (ATM), NASA is working with industry to develop prototype technologies for a UAS Traffic Management (UTM) system that would evolve airspace integration procedures for enabling safe, efficient low-altitude flight operations that autonomously manage UAS operating in an approved low-altitude airspace environment. UTM is a cloud-based system that will autonomously manage all traffic at low altitudes to include UASs being operated beyond visual line of sight of an operator. UTM would thus enable safe and efficient flight operations by providing fully integrated traffic management services such as airspace design, corridors, dynamic geofencing, severe weather and wind avoidance, congestion management, terrain avoidance, route planning re-routing, separation management, sequencing spacing, and contingency management. UTM removes the need for human operators to continuously monitor aircraft operating in approved areas. NASA envisions concepts for two types of UTM systems. The first would be a small portable system, which could be moved between geographical areas in support of operations such as precision agriculture and public safety. The second would be a Persistent system, which would support low-altitude operations in an approved area by providing continuous automated

A Study on the Measurement of Ultrasound Velocity to Evaluate Degradation of Low Voltage Cables for Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Cho; Kang, Suk Chull; Goo, Cheol Soo [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Kim, Jin Ho; Park, Jae Seok; Joo, Geum Jong; Park, Chi Seung [KAITEC, Seoul (Korea, Republic of)

2004-08-15

Several kinds of low voltage cables have been used in nuclear power plants for the supply of electric power, supervision, and the propagation of control signals. These low voltage tables must be inspected for safe and stable operation of nuclear power plants. In particular, the degradation diagnosis to estimate the integrity of low voltage rabies has recently been emphasized according to the long use of nuclear power plants. In order to evaluate their degradation, the surrounding temperature, hardness of insulation material, elongation at breaking point (EAB), etc. have been used. However, the measurement of temperature or hardness is not useful because of the absence of quantitative criteria; the inspection of a sample requires turning off of the power plant power; and, the electrical inspection method is not sufficiently sensitive from the initial through the middle stage of degradation. In this research, based on the theory that the ultrasonic velocity changes with relation to the degradation of the material, we measured the ultrasonic velocity as low voltage cables were degraded. To this end, an ultrasonic degradation diagnosis device was developed and used to measure the ultrasonic velocity with the clothing on the cable, and it was confirmed that the ultrasonic velocity changes according to the degradation of low voltage cables. The low voltage cables used in nuclear power plants were degraded at an accelerated rate, and EAB was measured in a tensile test conducted after the measurement of ultrasonic velocity. With the increasing degradation degree, the ultrasonic velocity decreased, whose potential as a useful parameter for the quantitative degradation evaluation was thus confirmed

Multi-gigabit low-power radiation-tolerant data links and improved data motion in trackers

International Nuclear Information System (INIS)

Miller, M; Brewer, F; Wang, D; Magazzu, G

2014-01-01

We present a set of links based on data-transmission IP in 130nm designed for rapid integration into ASIC designs. These links are designed for use in very high radiation environments as occur in high energy physics experiments. The designs are additionally low power and small area, easing integration with other electronic systems. These links are well suited to use in tracking detectors. Trackers, due to their close proximity to the collision, are subject to very high levels of radiation, and hence require such radiation hardened electronics. The portfolio of radiation hardened data transmission blocks consists of a 1Gbps serializer/deserializer with a very low power consumption ∼ 1mW for each. A differential transmitter and differential receiver rated at 3GHz, both designed to be much faster than needed, as insurance against radiation damage. Finally, the impact of a prototype low-latency, low-power ( < 60mW total link power) 5Gbps link is considered. Case analysis of the impacts of using lower powered, higher speed blocks in hypothetical trackers is studied, showing power improvements relative to alternative technologies

The objective is to achieve safe and competitive nuclear power

International Nuclear Information System (INIS)

Mattila, L.

1996-01-01

The 440 nuclear power plants in operation in the world today produce nearly one fifth of the world's electricity. Few new nuclear power plants are currently under construction in the West. Among the major factors slowing down the increase of nuclear power are the negative public opinion and the poor competitiveness of large plant units. In contrast, some of the countries in the Far East are busy building new nuclear power plant units. New advanced nuclear power plant types have been under development; the objective is to continue to improve safety and to raise the competitiveness. Increasing attention is also paid to measures extending the service life of the present power plants. Gas-cooled high-temperature reactors and liquid-metal-cooled breeder reactors appear to be promising alternatives. Practical experience of both plant types is available on the prototype level. Considerable sums of public research funds are spent towards the development of fusion technology. It is, however, unrealistic to expect fusion to become an important commercial source of energy before the middle of next century. (orig.) (4 figs.)