Benchmarks with diffusion theory and transport theory

International Nuclear Information System (INIS)

Cunha Menezes Filho, A. da; Souza, A.L. de.

1984-01-01

The multiplication factor and some spectral indices for five critical assemblies (ZPR-6-7, ZPR-3-11, GODIVA, BIG-TEN and FLATTOP) are calculated by Diffusion and Transport Theory, with group constants generated by MC 2 (for diffusion calculations) and by NJOY (for transport calculations). The discrepancies encountered in the ZPR-6-7 spectra, can be tracked to the large differences in the elastic cross section for Iron, calculated by MC 2 and NJOY. (Author) [pt

Re-interpretation of the ERMINE-V experiment validation of fission product integral cross section in the fast energy range

Science.gov (United States)

Ros, Paul; Leconte, Pierre; Blaise, Patrick; Naymeh, Laurent

2017-09-01

The current knowledge of nuclear data in the fast neutron energy range is not as good as in the thermal range, resulting in larger propagated uncertainties in integral quantities such as critical masses or reactivity effects. This situation makes it difficult to get the full benefit from recent advances in modeling and simulation. Zero power facilities such as the French ZPR MINERVE have already demonstrated that they can contribute to significantly reduce those uncertainties thanks to dedicated experiments. Historically, MINERVE has been mainly dedicated to thermal spectrum studies. However, experiments involving fast-thermal coupled cores were also performed in MINERVE as part of the ERMINE program, in order to improve nuclear data in fast spectra for the two French SFRs: PHENIX and SUPERPHENIX. Some of those experiments have been recently revisited. In particular, a full characterization of ZONA-1 and ZONA-3, two different cores loaded in the ERMINE V campaign, has been done, with much attention paid to possible sources of errors. It includes detailed geometric descriptions, energy profiles of the direct and adjoint fluxes and spectral indices obtained thanks to Monte Carlo calculations and compared to a reference fast core configuration. Sample oscillation experiments of separated fission products such as 103Rh or 99Tc, which were part of the ERMINE V program, have been simulated using recently-developed options in the TRIPOLI-4 code and compared to the experimental values. The present paper describes the corresponding results. The findings motivate in-depth studies for designing optimized coupled-core conditions in ZEPHYR, a new ZPR which will replace MINERVE and will provide integral data to meet the needs of Gen-III and Gen-IV reactors.

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)

Experimental measurement of zero power reactor transfer function

International Nuclear Information System (INIS)

Liang Shuhong

2011-01-01

In order to study the zero power reactor (ZPR) transfer function, the ZPR transfer function expression was deduced with the point reactor kinetics equation, which was disturbed by reactivity input response. Based on the Fourier analysis for the input of triangular wave, the relation between the transfer function and reactivity was got. Validating research experiment was made on the DF-VI fast ZPR. After the disturbed reactivity was measured, the experimental value of the transfer function was got. According to the experimental value and the calculated value, the expression of the ZPR transfer function is proved, whereas the disturbed reactivity is got from the transfer function. (authors)

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

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

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)

Critical experiments AT Pacific Northwest Laboratory

International Nuclear Information System (INIS)

Clayton, E.D.; Bierman, S.R.

1984-01-01

After a short description of the facility, a brief listing of the principal types of fuel forms and assembly geometries is provided. A number of experiments have recently been performed on plain fissionable units, or isolated assemblies of single units, that include measurements on solutions composed of Pu-U mixtures and critical experiment data on lattices of low enriched uranium in water. Experiments have been performed on planar arrays of containers with Pu solutions because of the lack of data in this field concerning the safe storage of nuclear fuel; others have been conducted on arrays of low enriched U lattice assemblies. Neutronic measurements to date have shown they can be used to provide additional benchmark data for improvement and validation of criticality codes. Studies have previously been made to ascertain the need for critical experiments in support of fuel recycle operations. The result of an effort to update the list of needed critical experiments is summarized in this section. Experiments are listed in support of uranium based fuels and fast breeder reactor fuels. An effort is made to identify those areas within the fuel cycle wherein the critical experiment data would be applied and to identify the experiments (and data) required to fulfill the needs in each of these areas. The type and form of fuel on which the data would be obtained also are identified. In presenting this information, no attempt is made to describe the experiments in detail, or to define the actual number of critical experiments that might be needed to provide the required data

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)

Reactor physics studies in the GCFR phase-II critical assembly

International Nuclear Information System (INIS)

Pond, R.B.

1976-09-01

The reactor physics studies performed in the gas cooled fast reactor (GCFR) mockup on ZPR-9 are covered. This critical assembly, designated Phase II in the GCFR program, had a single zone PuO 2 -UO 2 core composition and UO 2 radial and axial blankets. The assembly was built both with and without radial and axial stainless steel reflectors. The program included the following measurements: small-sample reactivity worths of reactor constituent materials (including helium); 238 U Doppler effect; uranium and plutonium reaction rate distributions; thorium, uranium, and plutonium α and reactor kinetics. Analysis of the measurements used ENDF/B-IV nuclear data; anisotropic diffusion coefficients were used to account for neutron streaming effects. Comparison of measurements and calculations to GCFR Phase I are also made

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)

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.

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

Verification Survey of the Building 315 Zero Power Reactor-6 Facility, Argonne National Laboratory-East, Argonne, Illinois

International Nuclear Information System (INIS)

W. C. Adams

2007-01-01

Oak Ridge Institute for Science and Education (ORISE) conducted independent verification radiological survey activities at Argonne National Laboratory's Building 315, Zero Power Reactor-6 facility in Argonne, Illinois. Independent verification survey activities included document and data reviews, alpha plus beta and gamma surface scans, alpha and beta surface activity measurements, and instrumentation comparisons. An interim letter report and a draft report, documenting the verification survey findings, were submitted to the DOE on November 8, 2006 and February 22, 2007, respectively (ORISE 2006b and 2007). Argonne National Laboratory-East (ANL-E) is owned by the U.S. Department of Energy (DOE) and is operated under a contract with the University of Chicago. Fundamental and applied research in the physical, biomedical, and environmental sciences are conducted at ANL-E and the laboratory serves as a major center of energy research and development. Building 315, which was completed in 1962, contained two cells, Cells 5 and 4, for holding Zero Power Reactor (ZPR)-6 and ZPR-9, respectively. These reactors were built to increase the knowledge and understanding of fast reactor technology. ZPR-6 was also referred to as the Fast Critical Facility and focused on fast reactor studies for civilian power production. ZPR-9 was used for nuclear rocket and fast reactor studies. In 1967, the reactors were converted for plutonium use. The reactors operated from the mid-1960's until 1982 when they were both shut down. Low levels of radioactivity were expected to be present due to the operating power levels of the ZPR's being restricted to well below 1,000 watts. To evaluate the presence of radiological contamination, DOE characterized the ZPRs in 2001. Currently, the Melt Attack and Coolability Experiments (MACE) and Melt Coolability and Concrete Interaction (MCCI) Experiments are being conducted in Cell 4 where the ZPR-9 is located (ANL 2002 and 2006). ANL has performed final

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)

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)

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

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

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)

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

Computer monitoring system for pilot plant nuclear criticality facility (solution ZPR)

International Nuclear Information System (INIS)

Hua Xiaokang; Liang Huiping

1999-01-01

The system is used for the Solution Zero Power Reactor physics measurement and safety monitoring. Its software modularization design enables multi-task real-time monitoring and off-time data processing. The system is labor/time saving to experimenters and will enhance the experiment precision and the reactor operation safety performance

Monte Carlo-based validation of the ENDF/MC2-II/SDX cell homogenization path

International Nuclear Information System (INIS)

Wade, D.C.

1979-04-01

The results are presented of a program of validation of the unit cell homogenization prescriptions and codes used for the analysis of Zero Power Reactor (ZPR) fast breeder reactor critical experiments. The ZPR drawer loading patterns comprise both plate type and pin-calandria type unit cells. A prescription is used to convert the three dimensional physical geometry of the drawer loadings into one dimensional calculational models. The ETOE-II/MC 2 -II/SDX code sequence is used to transform ENDF/B basic nuclear data into unit cell average broad group cross sections based on the 1D models. Cell average, broad group anisotropic diffusion coefficients are generated using the methods of Benoist or of Gelbard. The resulting broad (approx. 10 to 30) group parameters are used in multigroup diffusion and S/sub n/ transport calculations of full core XY or RZ models which employ smeared atom densities to represent the contents of the unit cells

Monte Carlo; based validation of the ENDF/MC2-II/SDX cell homogenization path

International Nuclear Information System (INIS)

Wade, D.C.

1978-11-01

The results are summarized of a program of validation of the unit cell homogenization prescriptions and codes used for the analysis of Zero Power Reactor (ZPR) fast breeder reactor critical experiments. The ZPR drawer loading patterns comprise both plate type and pin-calandria type unit cells. A prescription is used to convert the three dimensional physical geometry of the drawer loadings into one dimensional calculational models. The ETOE-II/MC 2 -II/SDX code sequence is used to transform ENDF/B basic nuclear data into unit cell average broad group cross sections based on the 1D models. Cell average, broad group anisotropic diffusion coefficients are generated using the methods of Benoist or of Gelbard. The resulting broad (approx. 10 to 30) group parameters are used in multigroup diffusion and S/sub n/ transport calculations of full core XY or RZ models which employ smeared atom densities to represent the contents of the unit cells

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)

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.

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.

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)

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

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

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)

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)

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

Medical Education to Enhance Critical Consciousness: Facilitators' Experiences.

Science.gov (United States)

Zaidi, Zareen; Vyas, Rashmi; Verstegen, Danielle; Morahan, Page; Dornan, Tim

2017-11-01

To analyze educators' experiences of facilitating cultural discussions in two global health professions education programs and what these experiences had taught them about critical consciousness. A multicultural research team conducted in-depth interviews with 16 faculty who had extensive experience facilitating cultural discussions. They analyzed transcripts of the interviews thematically, drawing sensitizing insights from Gramsci's theory of cultural hegemony. Collaboration and conversation helped the team self-consciously examine their positions toward the data set and be critically reflexive. Participant faculty used their prior experience facilitating cultural discussions to create a "safe space" in which learners could develop critical consciousness. During multicultural interactions they recognized and explicitly addressed issues related to power differentials, racism, implicit bias, and gender bias. They noted the need to be "facile in attending to pain" as learners brought up traumatic experiences and other sensitive issues including racism and the impact of power dynamics. They built relationships with learners by juxtaposing and exploring the sometimes-conflicting norms of different cultures. Participants were reflective about their own understanding and tendency to be biased. They aimed to break free of such biases while role modeling how to have the courage to speak up. Experience had given facilitators in multicultural programs an understanding of their responsibility to promote critical consciousness and social justice. How faculty without prior experience or expertise could develop those values and skills is a topic for future research.

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

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

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.

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.

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.

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.

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)

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)

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

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)

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

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

KUCA critical experiments using MEU fuel (II)

Energy Technology Data Exchange (ETDEWEB)

Kanda, Keiji; Hayashi, Masatoshi; Shiroya, Seiji; Kobayashi, Keiji; Fukui, Hiroshi; Mishima, Kaichiro; Shibata, Toshikazu [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka (Japan)

1983-09-01

Due to mutual concerns in the USA and Japan about the proliferation potential of highly-enriched uranium (HEU), a joint study program I was initiated between Argonne National Laboratory (ANL and Kyoto University Research Reactor Institute (KURRI) in 1978. In accordance with the reduced enrichment for research and test reactor (RERTR) program, the alternatives were studied for reducing the enrichment of the fuel to be used in the Kyoto University High Flux Reactor (KUHFR). The KUHFR has a distinct feature in its core configuration it is a coupled-core. Each annular shaped core is light-water-moderated and placed within a heavy water reflector with a certain distance between them. The phase A reports of the joint ANL-KURRI program independently prepared by two laboratories in February 1979, 3,4 concluded that the use of medium-enrichment uranium (MEU, 45%) in the KUHFR is feasible, pending results of the critical experiments in the Kyoto University Critical Assembly (KUCA) 5 and of the burnup test in the Oak Ridge Research Reactor 6 (ORR). An application of safety review (Reactor Installation License) for MEU fuel to be used in the KUCA was submitted to the Japanese Government in March 1980, and a license was issued in August 1980. Subsequently, the application for 'Authorization before Construction' was submitted and was authorized in September 1980. Fabrication of MEU fuel-elements for the KUCA experiments by CERCA in France was started in September 1980, and was completed in March 1981. The critical experiments in the KUCA with MEU fuel were started on a single-core in May 1981 as a first step. The first critical state of the core using MEU fuel was achieved at 312 p.m. in May 12, 1981. After that, the reactivity effects of the outer side-plates containing boron burnable poison were measured. At Munich Meeting in Sept., 1981, we presented a paper on critical mass and reactivity of burnable poison in the MEU core. Since then we carried out the following experiments

KUCA critical experiments using MEU fuel (II)

International Nuclear Information System (INIS)

Kanda, Keiji; Hayashi, Masatoshi; Shiroya, Seiji; Kobayashi, Keiji; Fukui, Hiroshi; Mishima, Kaichiro; Shibata, Toshikazu

1983-01-01

Due to mutual concerns in the USA and Japan about the proliferation potential of highly-enriched uranium (HEU), a joint study program I was initiated between Argonne National Laboratory (ANL and Kyoto University Research Reactor Institute (KURRI) in 1978. In accordance with the reduced enrichment for research and test reactor (RERTR) program, the alternatives were studied for reducing the enrichment of the fuel to be used in the Kyoto University High Flux Reactor (KUHFR). The KUHFR has a distinct feature in its core configuration it is a coupled-core. Each annular shaped core is light-water-moderated and placed within a heavy water reflector with a certain distance between them. The phase A reports of the joint ANL-KURRI program independently prepared by two laboratories in February 1979, 3,4 concluded that the use of medium-enrichment uranium (MEU, 45%) in the KUHFR is feasible, pending results of the critical experiments in the Kyoto University Critical Assembly (KUCA) 5 and of the burnup test in the Oak Ridge Research Reactor 6 (ORR). An application of safety review (Reactor Installation License) for MEU fuel to be used in the KUCA was submitted to the Japanese Government in March 1980, and a license was issued in August 1980. Subsequently, the application for 'Authorization before Construction' was submitted and was authorized in September 1980. Fabrication of MEU fuel-elements for the KUCA experiments by CERCA in France was started in September 1980, and was completed in March 1981. The critical experiments in the KUCA with MEU fuel were started on a single-core in May 1981 as a first step. The first critical state of the core using MEU fuel was achieved at 312 p.m. in May 12, 1981. After that, the reactivity effects of the outer side-plates containing boron burnable poison were measured. At Munich Meeting in Sept., 1981, we presented a paper on critical mass and reactivity of burnable poison in the MEU core. Since then we carried out the following experiments

Criticality experiments of the years 1981 and 1982

International Nuclear Information System (INIS)

Heinicke, W.; Tischer, A.

1983-01-01

This report presents a collection of published criticality experiments made in 1981 and 1982 and thus continues the collection of experimental data of this type commenced with the GRS report A-644 of November 1981, which covers criticality experiments of the years 1975 to 1980. The report gives the main data of about 30 publications which, just a those cited in the GRS report, can be retrieved from the improved KRITEXP data base using 14 index terms, and printed out at random sequence. The collection of experimental data is of particular value with regard to the licensing of all installations forming part of the nuclear fuel cycle, which is subject to the atomic energy law and requires the verification of computed criticality analyses by experimental data. (orig.) [de

Critical and sub-critical experiments on U-BeO lattices; Experiences critiques et sous-critiques sur reseaux U-BeO

Energy Technology Data Exchange (ETDEWEB)

Benoist, P.; Gourdon, Ch.; Martelly, J.; Sagot, M.; Wanner, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Deniz, V.; Joshi, B.V.; Sahai, K. [Atomic Energy Establishment Trombay (India)

1958-07-01

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)Fren. [French] Nous avons mesure par des experiences sous-critiques le laplacien matiere de reseaux uranium naturel-oxyde de beryllium, dont la maille carree a un pas de 15 cm, realises avec des barreaux d'uranium de diametres 2,60 - 2,92 - 3,56 - 4,40 cm. Une experience critique a ete faite ensuite avec des barres creuses d'uranium enrichi a 1,35 pour cent; l'etude des reseaux U-BeO de pas 18,03 cm est actuellement en cours. (auteur)

Critical and sub-critical experiments on U-BeO lattices; Experiences critiques et sous-critiques sur reseaux U-BeO

Energy Technology Data Exchange (ETDEWEB)

Benoist, P; Gourdon, Ch; Martelly, J; Sagot, M; Wanner, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Deniz, V; Joshi, B V; Sahai, K [Atomic Energy Establishment Trombay (India)

1958-07-01

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)Fren. [French] Nous avons mesure par des experiences sous-critiques le laplacien matiere de reseaux uranium naturel-oxyde de beryllium, dont la maille carree a un pas de 15 cm, realises avec des barreaux d'uranium de diametres 2,60 - 2,92 - 3,56 - 4,40 cm. Une experience critique a ete faite ensuite avec des barres creuses d'uranium enrichi a 1,35 pour cent; l'etude des reseaux U-BeO de pas 18,03 cm est actuellement en cours. (auteur)

Actinide neutron induced cross section measurements using the oscillation technique in the Minerve reactor

Energy Technology Data Exchange (ETDEWEB)

Bernard, B.; Leconte, P.; Gruel, A.; Antony, M.; Di-Salvo, J.; Hudelot, J.P.; Pepino, A.; Lecluze, A. [CEA Cadarache, DEN/CAD/DER/SPRC/LEPh, 13 - Saint-Paul-lez-Durance (France)

2009-07-01

CEA is deeply involved research programs concerning nuclear fuel advanced studies (actinides, plutonium), waste management, the scientific and technical support of French PWR reactors and EPR reactor, and innovative systems. In this framework, specific neutron integral experiments have been carried out in the critical ZPR (zero power reactor) facilities of the CEA at Cadarache such as MINERVE, EOLE and MASURCA. This paper deals with MINERVE Pool Reactor experiments. MINERVE is mainly devoted to neutronics studies of different reactor core types. The aim is to improve the knowledge of the integral absorption cross sections of actinides (OSMOSE program), of new absorbers (OCEAN program) and also for fission Products (CBU program) in thermal, epithermal and fast neutron spectra. (authors)

Criticality Experiments Performed in Saclay and Valduc Centers, France (1958-2002)

International Nuclear Information System (INIS)

Barbry, F.; Grivot, P.; Girault, E.; Fouillaud, P.; Cousinou, P.; Poullot, G.; Anno, J.; Bordy, J.M.; Doutriaux, D.

2003-01-01

Since 1958, the Commissariat a l'Energie Atomique and then the Institut de Radioprotection et de Surete Nucleaire (previously the Institut de Protection et de Surete Nucleaire) have carried out criticality experiments first in Saclay and then in the Valduc criticality laboratory. This paper is a survey of the programs conducted during the last 45 yr with the different apparatuses. This paper also gives information about plans for the future. Programs are presented following the chronology and the International Criticality Safety Benchmark Evaluation Project classification. Among the numerous series of experiments, now 22 series (corresponding to 407 configurations) have been included in the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments'

Bibliography for nuclear criticality accident experience, alarm systems, and emergency management

International Nuclear Information System (INIS)

Putman, V.L.

1995-09-01

The characteristics, detection, and emergency management of nuclear criticality accidents outside reactors has been an important component of criticality safety for as long as the need for this specialized safety discipline has been recognized. The general interest and importance of such topics receives special emphasis because of the potentially lethal, albeit highly localized, effects of criticality accidents and because of heightened public and regulatory concerns for any undesirable event in nuclear and radiological fields. This bibliography lists references which are potentially applicable to or interesting for criticality alarm, detection, and warning systems; criticality accident emergency management; and their associated programs. The lists are annotated to assist bibliography users in identifying applicable: industry and regulatory guidance and requirements, with historical development information and comments; criticality accident characteristics, consequences, experiences, and responses; hazard-, risk-, or safety-analysis criteria; CAS design and qualification criteria; CAS calibration, maintenance, repair, and testing criteria; experiences of CAS designers and maintainers; criticality accident emergency management (planning, preparedness, response, and recovery) requirements and guidance; criticality accident emergency management experience, plans, and techniques; methods and tools for analysis; and additional bibliographies

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…

The Pajarito Site operating procedures for the Los Alamos Critical Experiments Facility

International Nuclear Information System (INIS)

Malenfant, R.E.

1991-12-01

Operating procedures consistent with DOE Order 5480.6, and the American National Standard Safety Guide for the Performance of Critical Experiments are defined for the Los Alamos Critical Experiments Facility (LACEF) of the Los Alamos National Laboratory. These operating procedures supersede and update those previously published in 1983 and apply to any criticality experiment performed at the facility. 11 refs

VIM: Initial ENDF/B-VI experience

International Nuclear Information System (INIS)

Blomquist, R.N.

1997-01-01

The VIM Monte Carlo particle transport code uses detailed continuous-energy cross sections produced from ENDF/B data by a set of specialized codes developed or adapted for use at Argonne National Laboratory. ENDF/B-IV data were used until about 1979, and Version V data since then. These VIM libraries were extensively benchmarked against the MC 2 -2 code and against ZPR and ZPPR criticals for fast spectrum calculations, as well as other fast and thermal experiments and calculations. Recently, the cross section processing codes have been upgraded to accommodate ENDF/B-VI files, and a small library has been tested. Several fundamental tasks comprise the construction of a faithful representation of ENDF data for VIM calculations: (1) The resolved resonance parameters are converted to Doppler-broadened continuous-energy cross sections with energy grids suitable for linear-linear interpolation. (2) The unresolved resonance parameter distributions are sampled to produce many (40-400) resonance ladders in each energy band. These are converted to Doppler-broadened continuous energy resonance cross sections that are then binned by cross section, accumulating ladders until statistical convergence, the result being probability tables of total cross sections and conditional mean scattering and fission cross sections. VIM samples these tables at run time, and File 3 back ground cross sections are added. (3) Anisotropic angular distribution data are converted to angular probability tables. All other ENDF data are unmodified, except for format

Critical experiments on low enriched uranyl nitrate solution with STACY

International Nuclear Information System (INIS)

Miyoshi, Yoshinori

1996-01-01

As the STACY started steady operations, systematic criticality data on low enriched uranyl nitrate solution system could be accumulated. Main experimental parameters for the cylindrical tank of 60 cm in diameter were uranium concentration and the reflector condition. Basic data on a simple geometry will be helpful for the validation of the standard criticality safety codes, and for evaluating the safety margin included in the criticality designs. Experiments on the reactivity effects of structural materials such as borated concrete and polyethylene are on schedule next year as the second series of experiments using 10 wt% enriched uranyl solution. Furthermore, neutron interacting experiments with two slab tanks will be performed to investigate the fundamental properties of neutron interaction effects between core tanks. These data will be useful for making more reasonable calculation models and for evaluating the safety margin in the criticality designs for the multiple unit system. (J.P.N.)

Critical experiments for large scale enriched uranium solution handling

International Nuclear Information System (INIS)

Tanner, J.E.; Forehand, H.M.

1985-01-01

The authors have performed 17 critical experiments with a concentrated aqueous uranyl nitrate solution contained in an annular cylindrical tank, with annular cylindrical absorbers of stainless steel and/or polyethylene inside. k/sub eff/ calculated by KENO IV, employing 16-group Hansen-Roach cross sections, average 0.977. There is a variation of the calculational bias among the separate experiments, but it is too small to allow assigning it to specific components of the equipment. They are now performing critical experiments with a more concentrated uranyl nitrate solution in pairs of very squat cylindrical tanks with disc shaped absorbers and reflectors of carbon steel, stainless steel, nitronic-50, plain and borated polyethylene. These experiments are in support of upgrading fuel reprocessing at the Idaho Chemical Processing Plant

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)

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)

The physics design of EBR-II

International Nuclear Information System (INIS)

Loewenstein, W.B.

1962-01-01

The physics design oi EBR-II. Calculations of the static, dynamic and long-term reactivity behaviour of EBR-II are reported together with results and analysis of EBR-II dry critical and ZPR-III mock-up experiments. Particular emphasis is given to reactor-physics design problems which arise after the conceptual design is established and before the reactor is built or placed into operation. Reactor-safety analyses and hazards-evaluation considerations are described with their influence on the reactor design. The manner of utilizing the EBR-II mock-up on ZPR-III data and the EBR-II dry critical data is described. These experiments, their analysis and theoretical predictions are the basis for predetermining the physics behaviour of the reactor system. The limitations inherent in applying the experimental data to the performance of the power-reactor system are explored in some detail. This includes the specification of reactor core size and/or fuel-alloy enrichment, provisions for adequate operating and shut-down reactivity, determination of operative temperature and power coefficients of reactivity, and details of power- and flux-distribution as a function of position within the reactor structure. The overall problem of transferring information from simple idealized analytical or experimental geometry to actual hexagonal reactor geometry is described. Nuclear performance, including breeding, of the actual reactor system is compared with that of the idealized conceptual system. The long-term reactivity and power behaviour of the reactor blanket is described within the framework of the proposed cycling of the fuel and blanket alloy. Safety considerations, including normal and abnormal rates of reactivity-insertion, the implication of postulated reactivity effects based on the physical behaviour of the fuel alloy and reactor structure as well as extrapolation of TREAT experiments to the EBR-II system are analysed. The EBR-II core melt-down problem is reviewed. (author

Criticality calculations in reactor accelerator coupling experiment (Race)

International Nuclear Information System (INIS)

Reda, M.A.; Spaulding, R.; Hunt, A.; Harmon, J.F.; Beller, D.E.

2005-01-01

A Reactor Accelerator Coupling Experiment (RACE) is to be performed at the Idaho State University Idaho Accelerator Center (IAC). The electron accelerator is used to generate neutrons by inducing Bremsstrahlung photon-neutron reactions in a Tungsten- Copper target. This accelerator/target system produces a source of ∼1012 n/s, which can initiate fission reactions in the subcritical system. This coupling experiment between a 40-MeV electron accelerator and a subcritical system will allow us to predict and measure coupling efficiency, reactivity, and multiplication. In this paper, the results of the criticality and multiplication calculations, which were carried out using the Monte Carlo radiation transport code MCNPX, for different coupling design options are presented. The fuel plate arrangements and the surrounding tank dimensions have been optimized. Criticality using graphite instead of water for reflector/moderator outside of the core region has been studied. The RACE configuration at the IAC will have a criticality (k-effective) of about 0,92 and a multiplication of about 10. (authors)

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)

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

Results of 16 years' experiments at the critical facility of Valduc

International Nuclear Information System (INIS)

Houelle, M.; Mangin, D.; Maubert, L.

After briefly recalling the sub-critical approach procedure, the fields of experimental studies on criticality explored at the Valduc Criticality Station since 1963 are listed. This was the year in which the ''appareillage B'' went into service as the first installation of sub-critical experiments of the Section [fr

Weightless experiments to probe universality of fluid critical behavior

Science.gov (United States)

Lecoutre, C.; Guillaument, R.; Marre, S.; Garrabos, Y.; Beysens, D.; Hahn, I.

2015-06-01

Near the critical point of fluids, critical opalescence results in light attenuation, or turbidity increase, that can be used to probe the universality of critical behavior. Turbidity measurements in SF6 under weightlessness conditions on board the International Space Station are performed to appraise such behavior in terms of both temperature and density distances from the critical point. Data are obtained in a temperature range, far (1 K) from and extremely close (a few μ K ) to the phase transition, unattainable from previous experiments on Earth. Data are analyzed with renormalization-group matching classical-to-critical crossover models of the universal equation of state. It results that the data in the unexplored region, which is a minute deviant from the critical density value, still show adverse effects for testing the true asymptotic nature of the critical point phenomena.

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

Mock-up critical experiments for prototype fast breeder reactor 'Monju'

International Nuclear Information System (INIS)

Zukeran, Atsushi; Inoue, Teruji; Suzuki, Takeo; Kawashima, Kanau

1976-01-01

The mock-up criticality experiments for Monju are roughly divided into the full mock-up test using the ZEBRA of Winfrith Institute, UK AEA, and the partial mock-up experiment with FCA of JAERI. The former test has been carried out over 18 months from September 1971 as the Japan-UK cooperative research project MOZART. With the FCA, the experiment complementing the MOZART has been carried out, focusing on the nuclear characteristics of Monju which can be simulated with a relatively small core, and the experiment on highly enriched control rods and shielding is being continued now with the FCA 7 core. The experimental data of the MOZART and the ZPPR series in USA were exchanged at the international symposium in Tokyo, thus the prediction and the accuracy evaluation of the nuclear characteristics of Monju became possible, and the highly reliable core design was able to be accomplished. The simulated criticality experiment is necessary for directly grasping the reliability of calculated values in comparison with the experimental values, and also for the experimental prediction of the nuclear characteristics. The outline and the analysis of the simulated criticality experiment such as reactivity factor, control rod value, reaction rate distribution and sodium void reactivity are described, and the reflection of the results to the design of the core of Monju is explained. (Kako, I.)

International Handbook of Evaluated Criticality Safety Benchmark Experiments - ICSBEP (DVD), Version 2013

International Nuclear Information System (INIS)

2013-01-01

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 Organisation for Economic Co-operation and Development (OECD) Nuclear Energy Agency (NEA) in 1995. This handbook contains criticality safety benchmark specifications that have been derived from experiments performed at various nuclear critical experiment 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 nearly 66,000 pages and contain 558 evaluations with benchmark specifications for 4,798 critical, near critical or subcritical configurations, 24 criticality alarm placement/shielding configurations with multiple dose points for each and 200 configurations that have been categorised as fundamental physics measurements that are relevant to criticality safety applications. New to the Handbook are benchmark specifications for Critical, Bare, HEU(93.2)- Metal Sphere experiments referred to as ORSphere that were performed by a team of experimenters at Oak Ridge National Laboratory in the early 1970's. A photograph of this assembly is shown on the front cover

Deconstructing Global Markets through Critical Performative Experiences in Puerto Rico

Science.gov (United States)

Medina, Carmen Liliana; Weltsek, Gustave J.

2013-01-01

Critical Performative Pedagogies, the idea that "The nature of drama as a once removed creative experience turns non-critical implicit classroom identity formation into explicit identity performance as it asks participants to actively reflect upon how identity is created and engaged within fictional social interactions." (Weltsek and…

Results and preliminary analysis of critical experiments with interacting slab solution tanks

International Nuclear Information System (INIS)

Gurin, Victor N.; Ryazanov, Boris G.; Sviridov, Victor I.

2003-01-01

The paper presents the main results of several sets of critical experiments with two interacting similar slab tanks filled with aqueous solution of uranyl nitrate with uranium of 90% enrichment. These experiments were carried out at the RF-GS facility, Obninsk, Russia. Tanks with the thickness of 15 cm, width of 100 cm and height of 120 cm were used in these experiments. The experiments were conducted with partitions made of concrete, brick, polyethylene, cadmium, borated polyethylene. Consideration was given to the dependence of critical volume in each tank on the distance between the tanks and on the partition thickness. The tanks were filled with solutions of highly enriched uranium with its concentrations of 75 g/L and 250 g/L. Critical experiments were analysed with the MCNP 4A code based on the Monte-Carlo method and with the ENDF/B-V library. (author)

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

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)

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)

U-233 fuelled low critical mass solution reactor experiment PURNIMA II

International Nuclear Information System (INIS)

Srinivasan, M.; Chandramoleshwar, K.; Pasupathy, C.S.; Rasheed, K.K.; Subba Rao, K.

1987-01-01

A homogeneous U-233 uranyl nitrate solution fuelled BeO reflected, low critical mass reactor has been built at the Bhabha Atomic Research Centre, India. Christened PURNIMA II, the reactor was used for the study of the variation of critical mass as a function of fuel solution concentration to determine the minimum critical mass achievable for this geometry. Other experiments performed include the determination of temperature coefficient of reactivity, study of time behaviour of photoneutrons produced due to interaction between decaying U-233 fission product gammas and the beryllium reflector and reactor noise measurements. Besides being the only operational U-233 fuelled reactor at present, PURNIMA II also has the distinction of having attained the lowest critical mass of 397 g of fissile fuel for any operating reactor at the current time. The paper briefly describes the facility and gives an account of the experiments performed and results achieved. (author)

Results of the critical experiments concerning OTTO loading at the critical HTR-test facility KAHTER

International Nuclear Information System (INIS)

Drueke, V.; Litzow, W.; Paul, N.

1982-12-01

Critical experiments concerning OTTO loading are described. In the KAHTER facility an OTTO loading has been simulated, therefore the original KAHTER assembly was reconstructed. The determination of critical masses and reactivity worths of control rods and of additional absorber rods in the top reflector and in the upper cavity was of main interest for comparison with reactor following calculations. Besides this, reaction rates in different energy regions were measured in the upper part of the core, in the cavity and top reflector. (orig.) [de

Analysis and evaluation of critical experiments for validation of neutron transport calculations

International Nuclear Information System (INIS)

Bazzana, S.; Blaumann, H; Marquez Damian, J.I

2009-01-01

The calculation schemes, computational codes and nuclear data used in neutronic design require validation to obtain reliable results. In the nuclear criticality safety field this reliability also translates into a higher level of safety in procedures involving fissile material. The International Criticality Safety Benchmark Evaluation Project is an OECD/NEA activity led by the United States, in which participants from over 20 countries evaluate and publish criticality safety benchmarks. The product of this project is a set of benchmark experiment evaluations that are published annually in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. With the recent participation of Argentina, this information is now available for use by the neutron calculation and criticality safety groups in Argentina. This work presents the methodology used for the evaluation of experimental data, some results obtained by the application of these methods, and some examples of the data available in the Handbook. [es

Conceptual design of a digital control system for nuclear criticality experiments

International Nuclear Information System (INIS)

Rojas, S.P.

1994-04-01

Nuclear criticality is a concern in many areas of nuclear engineering including waste management, nuclear weapons testing and design, basic nuclear research, and nuclear reactor design and analysis. As in many areas of science and engineering, experimental work conducted in this field has provided a wealth of data and insight essential to the formulation of theory and the advancement in knowledge of fissioning systems. In light of the many diverse applications of nuclear criticality, there is a continuing interest to learn and understand more about the fundamental physical processes through continued experimentation. This thesis addresses the problem of setting up and programming a microprocessor-based digital control system (PLC) for a proposed critical experiment using, among other devices, a stepper motor, a joystick control mechanism, and switches. This experiment represents a revised configuration to test cylindrical nuclear waste packages. A Monte Carlo numerical study for the proposed critical assembly has been performed in order to illustrate how results from numerical calculations are used in the process of assembling the control system and to corroborate previous experimental data. In summary, a control system utilizing some common devices necessary to perform a critical experiment (stepper motor, push-buttons, etc.) has been assembled. Control components were sized using the results of a probabilistic computer code (MCNP). Finally, a program was written that illustrates the coupling between the hardware and the devices being controlled in the new test fixture

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.

Analysis of criticality experiments at SHE

International Nuclear Information System (INIS)

Takano, Makoto; Doi, Takeshi; Hirano, Mitsumasa; Shindo, Ryuichi; Oomura, Hiroshi

1982-03-01

In the report, the criticality experiments, which were conducted for the core configurations of Semi-Homogeneous Experimental Assembly (SHE)-8,12,13,14, are analyzed for the purpose of verifying the computer codes and calculational methods employed in the nuclear design of VHTR. The codes, DELIGHT-5 and CITATION calculate the neutron spectrum and the effective multiplication factor respectively. Each system of SHE is modeled by twodimensional R-Z, Triangular and threedimensional Triangular-Z geometries. Various effects such as axial buckling, modeling and the difference between diffusion and transport are also taken into account. Calculated values of effective multiplication factor show the disagreement of 1 - 3% from the values of experiments approximately. Therefore the analysis is considered to be inadequate to the verification and more precise analysis is required with the emphasis on how to model the system, condense the group constants and guess the buckling value for spectrum calculation. (author)

Technical specifications for the Oak Ridge Critical Experiments Facility

International Nuclear Information System (INIS)

Stinnett, R.M.

1986-01-01

These Technical Specifications for the Oak Ridge Critical Experiments Facility (CEF) delineate limiting conditions of operation for the facility. The CEF is used primarily for testing the High Flux Isotope Reactor (HFIR) fuel assemblies. Specifically, the Criticality Testing Unit, Liquid (CTUL), located in the CEF, is used for the HFIR fuel assembly test. The test is performed to satisfy the surveillance requirements of the HFIR Technical Specifications. The test is used to determine the water-submerged shutdown margin for each fuel assembly. 11 refs

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)

Sub-critical pulsed neutron experiments with uranyl nitrate solutions in spherical geometry

International Nuclear Information System (INIS)

Gurin, Victor N.; Ryazanov, Boris G.; Sviridov, Victor I.; Volnistov, Vladimir V.

2003-01-01

The pulse source method is used to study homogeneous solution assemblies. Three sets of sub-critical pulse experiments with spherical tanks filled with water solution of uranyl nitrate (90% enrichment) were carried out at the RF-GS facility, Obninsk, Russia. Seven spherical tanks with the volume within the range of 1.29 L to 19.8 L were used in the experiments. Three uranium concentrations were studied, i.e. 20.7, 29.6 and 37.5 g/L. The sub-critical experiments were analyzed with the MCNP 4A code based on the Monte-Carlo method, and with ENDF/B-V library. (author)

Proceedings of the workshop on integral experiment covariance data for critical safety validation

Energy Technology Data Exchange (ETDEWEB)

Stuke, Maik (ed.)

2016-04-15

For some time, attempts to quantify the statistical dependencies of critical experiments and to account for them properly in validation procedures were discussed in the literature by various groups. Besides the development of suitable methods especially the quality and modeling issues of the freely available experimental data are in the focus of current discussions, carried out for example in the Expert Group on Uncertainty Analysis for Criticality Safety Assessment (UACSA) of the OECD-NEA Nuclear Science Committee. The same committee compiles and publishes also the freely available experimental data in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. Most of these experiments were performed as series and might share parts of experimental setups leading to correlated results. The quality of the determination of these correlations and the underlying covariance data depend strongly on the quality of the documentation of experiments.

Proceedings of the workshop on integral experiment covariance data for critical safety validation

International Nuclear Information System (INIS)

Stuke, Maik

2016-04-01

For some time, attempts to quantify the statistical dependencies of critical experiments and to account for them properly in validation procedures were discussed in the literature by various groups. Besides the development of suitable methods especially the quality and modeling issues of the freely available experimental data are in the focus of current discussions, carried out for example in the Expert Group on Uncertainty Analysis for Criticality Safety Assessment (UACSA) of the OECD-NEA Nuclear Science Committee. The same committee compiles and publishes also the freely available experimental data in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. Most of these experiments were performed as series and might share parts of experimental setups leading to correlated results. The quality of the determination of these correlations and the underlying covariance data depend strongly on the quality of the documentation of experiments.

Simulated and Virtual Science Laboratory Experiments: Improving Critical Thinking and Higher-Order Learning Skills

Science.gov (United States)

Simon, Nicole A.

Virtual laboratory experiments using interactive computer simulations are not being employed as viable alternatives to laboratory science curriculum at extensive enough rates within higher education. Rote traditional lab experiments are currently the norm and are not addressing inquiry, Critical Thinking, and cognition throughout the laboratory experience, linking with educational technologies (Pyatt & Sims, 2007; 2011; Trundle & Bell, 2010). A causal-comparative quantitative study was conducted with 150 learners enrolled at a two-year community college, to determine the effects of simulation laboratory experiments on Higher-Order Learning, Critical Thinking Skills, and Cognitive Load. The treatment population used simulated experiments, while the non-treatment sections performed traditional expository experiments. A comparison was made using the Revised Two-Factor Study Process survey, Motivated Strategies for Learning Questionnaire, and the Scientific Attitude Inventory survey, using a Repeated Measures ANOVA test for treatment or non-treatment. A main effect of simulated laboratory experiments was found for both Higher-Order Learning, [F (1, 148) = 30.32,p = 0.00, eta2 = 0.12] and Critical Thinking Skills, [F (1, 148) = 14.64,p = 0.00, eta 2 = 0.17] such that simulations showed greater increases than traditional experiments. Post-lab treatment group self-reports indicated increased marginal means (+4.86) in Higher-Order Learning and Critical Thinking Skills, compared to the non-treatment group (+4.71). Simulations also improved the scientific skills and mastery of basic scientific subject matter. It is recommended that additional research recognize that learners' Critical Thinking Skills change due to different instructional methodologies that occur throughout a semester.

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)

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)

Alecto - results obtained with homogeneous critical experiments on plutonium 239, uranium 235 and uranium 233

International Nuclear Information System (INIS)

Bruna, J.G.; Brunet, J.P.; Caizegues, R.; Clouet d'Orval, Ch.; Kremser, J.; Tellier, H.; Verriere, Ph.

1965-01-01

In this report are given the results of the homogeneous critical experiments ALECTO, made on plutonium 239, uranium 235 and uranium 233. After a brief description of the equipment, the critical masses for cylinders of diameters varying from 25 to 42 cm, are given and compared with other values (foreign results, criticality guide). With respect to the specific conditions of neutron reflection in the ALECTO experiments the minimal values of critical masses are: Pu239 M c = 910 ± 10 g, U235 M c = 1180 ± 12 g and U233 M c = 960 ± 10 g. Experiments relating to cross sections and constants to be used on these materials are presented. Lastly, kinetic experiments allow to compare pulsed neutron methods to fluctuation methods [fr

GROWTH OF THE INTERNATIONAL CRITICALITY SAFETY AND REACTOR PHYSICS EXPERIMENT EVALUATION PROJECTS

Energy Technology Data Exchange (ETDEWEB)

J. Blair Briggs; John D. Bess; Jim Gulliford

2011-09-01

Since the International Conference on Nuclear Criticality Safety (ICNC) 2007, the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Experiment Evaluation Project (IRPhEP) have continued to expand their efforts and broaden their scope. Eighteen countries participated on the ICSBEP in 2007. Now, there are 20, with recent contributions from Sweden and Argentina. The IRPhEP has also expanded from eight contributing countries in 2007 to 16 in 2011. Since ICNC 2007, the contents of the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments1' have increased from 442 evaluations (38000 pages), containing benchmark specifications for 3955 critical or subcritical configurations to 516 evaluations (nearly 55000 pages), containing benchmark specifications for 4405 critical or subcritical configurations in the 2010 Edition of the ICSBEP Handbook. The contents of the Handbook have also increased from 21 to 24 criticality-alarm-placement/shielding configurations with multiple dose points for each, and from 20 to 200 configurations categorized as fundamental physics measurements relevant to criticality safety applications. Approximately 25 new evaluations and 150 additional configurations are expected to be added to the 2011 edition of the Handbook. Since ICNC 2007, the contents of the 'International Handbook of Evaluated Reactor Physics Benchmark Experiments2' have increased from 16 different experimental series that were performed at 12 different reactor facilities to 53 experimental series that were performed at 30 different reactor facilities in the 2011 edition of the Handbook. Considerable effort has also been made to improve the functionality of the searchable database, DICE (Database for the International Criticality Benchmark Evaluation Project) and verify the accuracy of the data contained therein. DICE will be discussed in separate papers at ICNC 2011. The status of the

Identifying Growth Conditions for Nicotiana benthimiana Resulting in Predictable Gene Expression of Promoter-Gus Fusion

Science.gov (United States)

Sandoval, V.; Barton, K.; Longhurst, A.

2012-12-01

Revoluta (Rev) is a transcription factor that establishes leaf polarity inArabidopsis thaliana. Through previous work in Dr. Barton's Lab, it is known that Revoluta binds to the ZPR3 promoter, thus activating the ZPR3 gene product inArabidopsis thaliana. Using this knowledge, two separate DNA constructs were made, one carrying revgene and in the other, the ZPR3 promoter fussed with the GUS gene. When inoculated in Nicotiana benthimiana (tobacco), the pMDC32 plasmid produces the Rev protein. Rev binds to the ZPR3 promoter thereby activating the transcription of the GUS gene, which can only be expressed in the presence of Rev. When GUS protein comes in contact with X-Gluc it produce the blue stain seen (See Figure 1). In the past, variability has been seen of GUS expression on tobacco therefore we hypothesized that changing the growing conditions and leaf age might improve how well it's expressed.

Sensitivity analysis of critical experiment with direct perturbation compared to TSUNAMI-3D sensitivity analysis

International Nuclear Information System (INIS)

Barber, A. D.; Busch, R.

2009-01-01

The goal of this work is to obtain sensitivities from direct uncertainty analysis calculation and correlate those calculated values with the sensitivities produced from TSUNAMI-3D (Tools for Sensitivity and Uncertainty Analysis Methodology Implementation in Three Dimensions). A full sensitivity analysis is performed on a critical experiment to determine the overall uncertainty of the experiment. Small perturbation calculations are performed for all known uncertainties to obtain the total uncertainty of the experiment. The results from a critical experiment are only known as well as the geometric and material properties. The goal of this relationship is to simplify the uncertainty quantification process in assessing a critical experiment, while still considering all of the important parameters. (authors)

Control and interpretation of criticality experiments on metallic assemblies

International Nuclear Information System (INIS)

Long, J.J.

1984-01-01

This paper deals with the principle of criticality experiment control with approach machines; to follow the reactivity evolution, one uses the classical method of the inverses of counting rates, then one shows how it is possible to extrapolate the approach curves that have been obtained [fr

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

International Nuclear Information System (INIS)

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

2013-02-01

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

A second simulated criticality accident dosimetry experiment

CERN Document Server

Adams, N

1973-01-01

This experiment was undertaken to facilitate training in criticality dose assessment by UKAEA and BNFL establishments with potential criticality hazards. Personal dosemeters, coins, samples of hair, etc. supplied by the seven participating establishments were attached to a man-phantom filled with a solution of sodium nitrate (simulating 'body-sodium'), and exposed to a burst of radiation from the AWRE pulsed reactor VIPER. The neutron and photon doses were each several hundred rads. Participants made two sets of dose assessments. The first, made solely from the evidence of their routine dosemeters the activation of body-sodium and standard monitoring data, simulated the initial dose assessment that would be made before the circumstances of a real incident were established. The second was made when the position and orientation of the phantom relative to the reactor and the shielding (20 cm of copper) between the reactor core and the phantom were disclosed. Neutron and photon dose assessments for comparison wit...

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

Science.gov (United States)

Graydon, Patrick J.; Holloway, C. Michael

2015-01-01

We need well-founded means of determining whether software is t for use in safety-critical applications. While software in industries such as aviation has an excellent safety record, the fact that software aws have contributed to deaths illustrates the need for justi ably high con dence in software. It is often argued that software is t for safety-critical use because it conforms to a standard for software in safety-critical systems. But little is known about whether such standards `work.' Reliance upon a standard without knowing whether it works is an experiment; without collecting data to assess the standard, this experiment is unplanned. This paper reports on a workshop intended to explore how standards could practicably be assessed. Planning the Unplanned Experiment: Assessing the Ecacy of Standards for Safety Critical Software (AESSCS) was held on 13 May 2014 in conjunction with the European Dependable Computing Conference (EDCC). We summarize and elaborate on the workshop's discussion of the topic, including both the presented positions and the dialogue that ensued.

Critical experiment tests of bowing and expansion reactivity calculations for LMRS

International Nuclear Information System (INIS)

Schaefer, R.W.

1988-01-01

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

Experience-Dependent Equilibration of AMPAR-Mediated Synaptic Transmission during the Critical Period

Directory of Open Access Journals (Sweden)

Kyung-Seok Han

2017-01-01

Full Text Available Experience-dependent synapse refinement is essential for functional optimization of neural circuits. However, how sensory experience sculpts excitatory synaptic transmission is poorly understood. Here, we show that despite substantial remodeling of synaptic connectivity, AMPAR-mediated synaptic transmission remains at equilibrium during the critical period in the mouse primary visual cortex. The maintenance of this equilibrium requires neurogranin (Ng, a postsynaptic calmodulin-binding protein important for synaptic plasticity. With normal visual experience, loss of Ng decreased AMPAR-positive synapse numbers, prevented AMPAR-silent synapse maturation, and increased spine elimination. Importantly, visual deprivation halted synapse loss caused by loss of Ng, revealing that Ng coordinates experience-dependent AMPAR-silent synapse conversion to AMPAR-active synapses and synapse elimination. Loss of Ng also led to sensitized long-term synaptic depression (LTD and impaired visually guided behavior. Our synaptic interrogation reveals that experience-dependent coordination of AMPAR-silent synapse conversion and synapse elimination hinges upon Ng-dependent mechanisms for constructive synaptic refinement during the critical period.

Sensitivity profiles calculated with the UNISENS system

International Nuclear Information System (INIS)

Claro, L.H.; Menezes, A.

1985-01-01

Sensitivity profiles of the multiplication factor and several central reaction ratios for benchmarks ZPR 6/7, ZPR 3/11, FLATTOP-25, GODIVA and BIG-TEN, are presented in grafic form. A possible utilization is showed throught some modification to the ENDF/B-IV data file proposed for version ENDF/B-V. (Author) [pt

Experience with performance based training of nuclear criticality safety engineers

International Nuclear Information System (INIS)

Taylor, R.G.

1993-01-01

Historically, new entrants to the practice of nuclear criticality safety have learned their job primarily by on-the-job training (OJT) often by association with an experienced nuclear criticality safety engineer who probably also learned their job by OJT. Typically, the new entrant learned what he/she needed to know to solve a particular problem and accumulated experience as more problems were solved. It is likely that more formalism will be required in the future. Current US Department of Energy requirements for those positions which have to demonstrate qualification indicate that it should be achieved by using a systematic approach such as performance based training (PBT). Assuming that PBT would be an acceptable mechanism for nuclear criticality safety engineer training in a more formal environment, a site-specific analysis of the nuclear criticality safety engineer job was performed. Based on this analysis, classes are being developed and delivered to a target audience of newer nuclear criticality safety engineers. Because current interest is in developing training for selected aspects of the nuclear criticality safety engineer job, the analysis i's incompletely developed in some areas. Details of this analysis are provided in this report

The experience of critically ill children: A phenomenological study of discomfort and comfort.

Science.gov (United States)

Carnevale, Franco A; Gaudreault, Josée

2013-01-01

Emerging evidence indicates that critically ill children are particularly at risk for incurring significant psychological harm. Little is known about these children's actual experiences. The aim of the study was to examine children's experience of critical illness. The research question was: What are a critically ill child's sources of discomfort and comfort? Interpretive phenomenology was selected as the study's method. Children's accounts were examined to identify what they considered meaningful, in terms of their experienced discomfort and comfort. Data sources included formal and informal interviews with child-participants, drawings provided by some participants, and field-notes documenting observed non-verbal data. Twelve children were enrolled in the study, ranging from 3 to 17years of age; including four girls and eight boys. Although all participants were able to discuss the discomfort and comfort they experienced, they reported difficulties in remembering part or most of their experience. Some participants characterized their Pediatric Intensive Care Unit stay quite favourably or as "not that bad", while some described their experience unfavourably. Diverse types of discomforts were reported, including fears and worries, hurt and pain, invasive interventions, missing significant people, noise, food or eating problems, boredom, physical symptoms, as well as four additional discomforts reported by individual participants. Several sources of comfort were described, including parents, visitors and friends, hospital staff (principally nurses), stuffed animal/favourite blanket, entertainment and play, food, selected medical interventions, thinking of going home, being able to walk or run, sleep, waking up, gifts, along with two other comforts reported by individual participants. Embodiment and a tension between aloneness and being with were identified as the principal phenomena underlying these children's experiences. The findings complement existing knowledge

Modeling of FREYA fast critical experiments with the Serpent Monte Carlo code

International Nuclear Information System (INIS)

Fridman, E.; Kochetkov, A.; Krása, A.

2017-01-01

Highlights: • FREYA – the EURATOM project executed to support fast lead-based reactor systems. • Critical experiments in the VENUS-F facility during the FREYA project. • Characterization of the critical VENUS-F cores with Serpent. • Comparison of the numerical Serpent results to the experimental data. - Abstract: The FP7 EURATOM project FREYA has been executed between 2011 and 2016 with the aim of supporting the design of fast lead-cooled reactor systems such as MYRRHA and ALFRED. During the project, a number of critical experiments were conducted in the VENUS-F facility located at SCK·CEN, Mol, Belgium. The Monte Carlo code Serpent was one of the codes applied for the characterization of the critical VENUS-F cores. Four critical configurations were modeled with Serpent, namely the reference critical core, the clean MYRRHA mock-up, the full MYRRHA mock-up, and the critical core with the ALFRED island. This paper briefly presents the VENUS-F facility, provides a detailed description of the aforementioned critical VENUS-F cores, and compares the numerical results calculated by Serpent to the available experimental data. The compared parameters include keff, point kinetics parameters, fission rate ratios of important actinides to that of U235 (spectral indices), axial and radial distribution of fission rates, and lead void reactivity effect. The reported results show generally good agreement between the calculated and experimental values. Nevertheless, the paper also reveals some noteworthy issues requiring further attention. This includes the systematic overprediction of reactivity and systematic underestimation of the U238 to U235 fission rate ratio.

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)

Technical specifications for the Pajarito Site Critical Experiments Facility

International Nuclear Information System (INIS)

Malenfant, R.E.; Paxton, H.C.

1980-12-01

This document is to satisfy the requirement for technical specifications spelled out in DOE Manual Chapter 0540, Safety of DOE-Owned Reactors. Technical specifications are defined in Sec. 0540-048, and the requirement for them appears in Sec. 0540-015. The following technical specifications update the document, Technical Specifications for the Pajarito Site Critical Experiments Facility

Analysis of Doppler effect with JAERI-Fast set

International Nuclear Information System (INIS)

Takano, Hideki; Matsui, Yasushi.

1977-07-01

Temperature dependence of group cross sections in the JAERI-Fast set versions I, IR, II and IIR has been tested from the analysis of Doppler experiments performed with two different methods. One is Doppler reactivity measurement for the whole core of SEFOR assembly, and the other sample Doppler reactivity measurement for natural UO 2 in FCA assemblies V-1, V-2, VI-1 and VI-2, ZPR-6-7, ZPR-3-47, and ZPPR-2 and 3. Doppler effects were calculated with one- and two-dimensional diffusion 1-st order perturbation code DOPP2D. The results calculated with the JAERI-Fast set versions II and IIR are in good agreement with the experimental ones. In these calculation, resonance heterogeneity effect, stainless-stell buffer effect and plate heterogeneity effect are considered, and these effects contribute significantly to Doppler effect. (auth.)

Environmental assessment for consolidation of certain materials and machines for nuclear criticality experiments and training

International Nuclear Information System (INIS)

1996-01-01

In support of its assigned missions and because of the importance of avoiding nuclear criticality accidents, DOE has adopted a policy to reduce identifiable nuclear criticality safety risks and to protect the public, workers, government property and essential operations from the effects of a criticality accident. In support of this policy, the Los Alamos Critical Experiments Facility (LACEF) at the Los Alamos National Laboratory (LANL) Technical Area (TA) 18, provides a program of general purpose critical experiments. This program, the only remaining one of its kind in the United States, seeks to maintain a sound basis of information for criticality control in those physical situations that DOE will encounter in handling and storing fissionable material in the future, and ensuring the presence of a community of individuals competent in practicing this control

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

An Anesthetist’s Experience and the Incidence of Critical Cases in Ambulatory Surgery

Directory of Open Access Journals (Sweden)

R. V. Bolshedvorov

2009-01-01

Full Text Available Objective: to evaluate the impact of experience on the quality of anesthesia in ambulatory surgery. Materials and methods. The authors undertook a study of the role of experience and specialization on the occurrence of complications in ambulatory anesthesia care. By using the internal audit and calculating the frequency of critical cases, they examined the results of the work of two groups of anesthetists: 1 medical beginners after 2-year adjunct practice and 2 one-day hospital specialists having an at least 7-year practice length. Results. In the beginner group, the number of critical cases per operation was twice higher than that in the experienced specialists. The paper shows the detrimental pattern of the residual principle in selecting anesthetists for work at a one-day hospital and provides evidence that specialization is required in the area under discussion. Key words: ambulatory anesthesiology, role of an anesthetist’s experience, critical cases.

Calculated k-effectives for light water reactor typical, U + Pu nitrate solution critical experiments

International Nuclear Information System (INIS)

Primm, R.T. III; Mincey, J.F.

1982-01-01

The Department of Energy's Consolidated Fuel Reprocessing Program has as a goal the design of nuclear fuel reprocessing equipment. In order to validate computer codes used for criticality analyses in the design of such equipment, k-effectives have been calculated for several U + Pu nitrate solution critical experiments. As of January 1981, descriptions of 45 unpoisoned, U + Pu solution experiments were available in the open literature. Twelve of these experiments were performed with solutions which have physical characteristics typical of dissolved, light water reactor fuel. This paper contains a discussion of these twelve experiments, a review of the calculational procedure used to determine k-effectives, and the results of the calculations

Analysis of benchmark critical experiments with ENDF/B-VI data sets

International Nuclear Information System (INIS)

Hardy, J. Jr.; Kahler, A.C.

1991-01-01

Several clean critical experiments were analyzed with ENDF/B-VI data to assess the adequacy of the data for U 235 , U 238 and oxygen. These experiments were (1) a set of homogeneous U 235 -H 2 O assemblies spanning a wide range of hydrogen/uranium ratio, and (2) TRX-1, a simple, H 2 O-moderated Bettis lattice of slightly-enriched uranium metal rods. The analyses used the Monte Carlo program RCP01, with explicit three-dimensional geometry and detailed representation of cross sections. For the homogeneous criticals, calculated k crit values for large, thermal assemblies show good agreement with experiment. This supports the evaluated thermal criticality parameters for U 235 . However, for assemblies with smaller H/U ratios, k crit values increase significantly with increasing leakage and flux-spectrum hardness. These trends suggest that leakage is underpredicted and that the resonance eta of the ENDF/B-VI U 235 is too large. For TRX-1, reasonably good agreement is found with measured lattice parameters (reaction-rate ratios). Of primary interest is rho28, the ratio of above-thermal to thermal U 238 capture. Calculated rho28 is 2.3 (± 1.7) % above measurement, suggesting that U 238 resonance capture remains slightly overpredicted with ENDF/B-VI. However, agreement is better than observed with earlier versions of ENDF/B

Critical success factors for positive user experience in hotel websites:applying Herzberg’s two factor theory for user experience modeling

OpenAIRE

Sambhanthan, Arunasalam; Good, Alice

2013-01-01

This research presents the development of a critical success factor matrix for increasing positive user experience of hotel websites based upon user ratings. Firstly, a number of critical success factors for web usability have been identified through the initial literature review. Secondly, hotel websites were surveyed in terms of critical success factors identified through the literature review. Thirdly, Herzberg’s motivation theory has been applied to the user rating and the critical succ...

2010 Criticality Accident Alarm System Benchmark Experiments At The CEA Valduc SILENE Facility

International Nuclear Information System (INIS)

Miller, Thomas Martin; Dunn, Michael E.; Wagner, John C.; McMahan, Kimberly L.; Authier, Nicolas; Jacquet, Xavier; Rousseau, Guillaume; Wolff, Herve; Piot, Jerome; Savanier, Laurence; Baclet, Nathalie; Lee, Yi-kang; Masse, Veronique; Trama, Jean-Christophe; Gagnier, Emmanuel; Naury, Sylvie; Lenain, Richard; Hunter, Richard; Kim, Soon; Dulik, George Michael; Reynolds, Kevin H.

2011-01-01

Several experiments were performed at the CEA Valduc SILENE reactor facility, which are intended to be published as evaluated benchmark experiments in the ICSBEP Handbook. These evaluated benchmarks will be useful for the verification and validation of radiation transport codes and evaluated nuclear data, particularly those that are used in the analysis of CAASs. During these experiments SILENE was operated in pulsed mode in order to be representative of a criticality accident, which is rare among shielding benchmarks. Measurements of the neutron flux were made with neutron activation foils and measurements of photon doses were made with TLDs. Also unique to these experiments was the presence of several detectors used in actual CAASs, which allowed for the observation of their behavior during an actual critical pulse. This paper presents the preliminary measurement data currently available from these experiments. Also presented are comparisons of preliminary computational results with Scale and TRIPOLI-4 to the preliminary measurement data.

Potential impacts of ENDF/B-V on critical experiment analysis based on ZEBRA-8 criticals

Energy Technology Data Exchange (ETDEWEB)

Choong, T S

1982-06-01

The ZEBRA-8 series of null-zone measurements featured a different neutron spectrum for each assembly. The experiments were designed for the purpose of basic data testing. The series cover a range of spectra both harder and softer than that for the LMFBR. The potential impacts of the newly released ENDF/BV cross section library on LMFBR critical exeriment analysis are discussed based on analysis of ZEBRA-8 series.

Sudden death in paediatrics as a traumatic experience for critical care nurses.

Science.gov (United States)

Lima, Lígia; Gonçalves, Sandra; Pinto, Cândida

2018-01-01

Research shows that nurses working in critical care units and in particular, paediatric units, are at risk of developing symptoms of secondary traumatic stress (STS). However, little attention has been given to this phenomenon when associated with situations of sudden death in paediatrics. This study aimed to examine the impact of sudden death in paediatrics on nurses working in paediatrics critical care units and to explore nurses' experiences of this event. This study used a mixed-methods design. The Impact of Event Scale - Revised was used for investigating the presence of STS symptoms. In addition, an interview was conducted with six nurses. Fifty-seven percent of nurses responded to the surveys and six nurses were interviewed. The results showed that the sudden death of children and adolescents is an event that elicits symptoms of STS in nurses. The quantitative assessment, revealed that 19·4% presented total scores indicating high impact. The participants interviewed described experiences of subjective distress, such as intrusive thoughts, avoidance and hyperarousal. Other factors were also reported as influencing the experience of the sudden death of a child/adolescent, namely, the child's age, the cause of death and the family's reaction to the loss. According to the participants, the emotional impact was also determined by parenthood, previous training and professional experience. Sudden death in paediatric critical care units is one of the most difficult situations in nursing practice and elicits STS symptoms, which may severely impact the physical and psychological health of nurses and ultimately affect the quality of the provided care. This study emphasizes the need for promoting better conditions for professional practice, namely, with regard to emotional support, as well as training programmes for skills development in the area of management of traumatic situations and of communication with clients. © 2017 British Association of Critical Care

Fundamental-mode sources in approach to critical experiments

International Nuclear Information System (INIS)

Goda, J.; Busch, R.

2000-01-01

An equivalent fundamental-mode source is an imaginary source that is distributed identically in space, energy, and angle to the fundamental-mode fission source. Therefore, it produces the same neutron multiplication as the fundamental-mode fission source. Even if two source distributions produce the same number of spontaneous fission neutrons, they will not necessarily contribute equally toward the multiplication of a given system. A method of comparing the relative importance of source distributions is needed. A factor, denoted as g* and defined as the ratio of the fixed-source multiplication to the fundamental-mode multiplication, is used to convert a given source strength to its equivalent fundamental-mode source strength. This factor is of interest to criticality safety as it relates to the 1/M method of approach to critical. Ideally, a plot of 1/M versus κ eff is linear. However, since 1/M = (1 minus κ eff )/g*, the plot will be linear only if g* is constant with κ eff . When g* increases with κ eff , the 1/M plot is said to be conservative because the critical mass is underestimated. However, it is possible for g* to decrease with κ eff yielding a nonconservative 1/M plot. A better understanding of g* would help predict whether a given approach to critical will be conservative or nonconservative. The equivalent fundamental-mode source strength g*S can be predicted by experiment. The experimental method was tested on the XIX-1 core on the Fast Critical Assembly at the Japan Atomic Energy Research Institute. The results showed a 30% difference between measured and calculated values. However, the XIX-1 reactor had significant intermediate-energy neutrons. The presence of intermediate-energy neutrons may have made the cross-section set used for predicted values less than ideal for the system

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.

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

Critical power experiment with a tight-lattice 37-rod bundle

International Nuclear Information System (INIS)

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

2006-01-01

Since most of critical power or CHF data have been collected in tube, annulus, or BWR geometries under BWR flow conditions, critical power data for highly tight and triangular lattice bundles under low mass velocity are indispensable for thermal-hydraulic design of Reduced-Moderation Water Reactor. Large-scale thermal-hydraulic experiments which use a basic 37-rod bundle test section (rod diameter: 13.0 mm, gap width between rods: 1.3 mm) were therefore carried out in this study within range of 2-9 MPa in pressure and 150-1,000 kg/(m 2 ·s) in mass velocity. Fundamental characteristics of boiling transition were investigated through effects of flow parameter on critical power and those of rod number. It was confirmed that the fundamental characteristics in 37-rod bundle are similar to those in 7-rod bundle and in case of the BWR geometry. The results of the transverse non-uniform power distribution test and subchannel analysis suggest that the critical power becomes higher when the transverse local quality distribution closes to uniform. (author)

The need for integral critical experiments with low-moderated MOX fuels

International Nuclear Information System (INIS)

2004-01-01

The use of MOX fuel in commercial reactors is a means of burning plutonium originating from either surplus weapons or reprocessed irradiated uranium fuel. This requires the fabrication of MOX assemblies on an industrial scale. The OECD/NEA Expert Group on Experimental Needs for Criticality Safety has highlighted MOX fuel manufacturing, as an area in which there is a specific need for additional experimental data for validation purposes. Indeed, integral experiments with low-moderated MOX fuel are either scarce or not sufficiently accurate to provide an appropriate degree of validation of nuclear data and computer codes. New and accurate experimental data would enable a better optimisation of the fabrication process by decreasing the uncertainties in the determination of multiplication factors of configurations such as the homogenization of MOX powders. In this context, the OECD/NEA Nuclear Science Committee organised a workshop to address the following topics: expression and justification of the need for critical or near-critical experiments employing low-moderated MOX fuels; proposals for experimental programmes to address these needs; prospects for an international co-operative programme. The workshop was held at OECD headquarters in Paris on 14-15 April 2004. (author)

Risk management for operations of the LANL Critical Experiments Facility

International Nuclear Information System (INIS)

Paternoster, R.; Butterfield, K.

1998-01-01

The Los Alamos Critical Experiments Facility (LACEF) currently operates two burst reactors (Godiva-IV and Skua), one solution assembly [the Solution High-Energy Burst Assembly (SHEBA)], two fast-spectrum benchmark assemblies (Flattop and Big Ten), and five general-purpose remote assembly machines that may be configured with nuclear materials and assembled by remote control. Special nuclear materials storage vaults support these and other operations at the site. With this diverse set of operations, several approaches are possible in the analysis and management of risk. The most conservative approach would be to write a safety analysis report (SAR) for each assembly and experiment. A more cost-effective approach is to analyze the probability and consequences of several classes of operations representative of operations on each critical assembly machine and envelope the bounding case accidents. Although the neutron physics of these machines varies widely, the operations performed at LACEF fall into four operational modes: steady-state mode, approach-to-critical mode, prompt burst mode, and nuclear material operations, which can include critical assembly fuel loading. The operational sequences of each mode are very nearly identical, whether operated on one assembly machine or another. The use of an envelope approach to accident analysis is facilitated by the use of classes of operations and the use of bounding case consequence analysis. A simple fault tree analysis of operational modes helps resolve which operations are sensitive to human error and which are initiated by hardware of software failures. Where possible, these errors and failures are blocked by TSR LCOs. Future work will determine the probability of accidents with various initiators

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)

Use of research reactors in multidisciplinary education at Cornell University

International Nuclear Information System (INIS)

Clark, D.D.

1992-01-01

Multidisciplinary aspects of nuclear science and technology form a large part of the research and teaching activities of the Nuclear Science and Engineering (NS and E) Program at Cornell, and the two reactors housed in Ward Laboratory - a 500-kW TRIGA and a 100-W critical facility [zero-power reactor (ZPR)]- play a central role in those activities. Several primarily educational and multidisciplinary features of the NS and E program are described in this paper

Patient Experience: A Critical Indicator of Healthcare Performance.

Science.gov (United States)

Guler, Pamela H

2017-01-01

Patient experience has become a critical differentiator for healthcare organizations, and it will only grow in importance as transparency and consumerism dominate the healthcare landscape. Creating and sustaining a consistently exceptional experience that promotes patient engagement and the best outcomes is far more than just "satisfying" patients, going well beyond amenities that may be provided.Perception of care experience is often shaped by methods we use to address the biopsychosocial needs of patients. Building relationships and communicating well with our patients and families are primary approaches. In a complex healthcare situation, patients may not fully understand or remember the highly clinical nature of treatment. However, they always remember how we made them feel, how we communicated with them as a team, and what interactions they experienced while in our care.Patients who are fully informed and feel connected to their caregivers are often less anxious than those who are disengaged. Informed and engaged patients are enabled to participate in their healthcare. Organizations that focus on developing an accountable culture-one that inspires caregivers to communicate in a way that connects to patients' mind, body, and spirit while leveraging standard, evidence-based patient experience practices-find that patients' perception of care, or "the patient experience," is vastly improved.Adventist Health System has embarked on a journey to patient experience excellence with a commitment to whole-person care and standard patient experience practice across the system. Recognized with several national awards, we continue to strengthen our approach toward bringing all of our campuses and patient settings to sustained high-level performance. We have found that a combination of strong, accountable leadership; a focus on employee culture; engagement of physicians; standardized patient experience practices and education; and meaningful use of patient feedback are top

A Critical Study of C.F.Davis's Views on Revelatory Religious Experiences

Directory of Open Access Journals (Sweden)

Ali Shirvani

2010-12-01

Full Text Available Revelatory experiences which are regarded as a major type of religious experiences comprise what their subjects may call sudden convictions, inspiration, revelation, enlightenment, the mystical vision and flashes of insight. In Davis's point of view, these experiences have distinctive features: (i They are usually sudden and of short duration (ii the alleged new knowledge seems to the subject to have been acquired not through reasoning or sense perception (iii the alleged new knowledge usually seems to the subject to have been ' poured into ' or ' showered upon ' him her by an external agency (iv the revelations carry with them utter convicition (v the gained insights are often claimed to be impossible to put into words.  This paper is to present how Davis describes religious experiences of this category from a Christian philosophical approach to religion. It also studies her point of views from a critical Islamic mystical vision. Through this critical and comparative study, it would be revealed that what Davis claimed to be known as revelatory religious experiences has close relationship with what is called "Kashfe Ma'lanavi" (spiritual intuition in Islamic mysticism. These are examined closely in Muslims' mystical sources. Distinction between Prophet's revelation and other instances of revelatory religious experiences and exploring their main differences were of close attention for Muslim mystics (Orafa.

Optical observations on critical ionization velocity experiments in space

International Nuclear Information System (INIS)

Stenbaek-Nielsen, H.C.

1993-01-01

A number of Critical Ionization Velocity (CIV) experiments have been performed in space. CIV has been observed in laboratory experiments, but experiments in space have been inconclusive. Most space experiments have used barium which ionizes easily, and with emission lines from both neutrals and ions in the visible optical observations can be made from the ground. Also other elements, such as xenon, strontium and calcium, have been used. High initial ionization in some barium release experiments has been claimed due to CIV. However, a number of reactions between barium and the ambient plasma have been suggested as more likely processes. Currently the most popular process in this debate is charge exchange with O + . This process has a large cross section, but is it large enough? The cross section for charge exchange with calcium should be even larger, but in a double release of barium and calcium (part of the NASA CRRES release experiments) most ionization was observed from the barium release. Moreover, if charge exchange is the dominant process, the amount of ionization should relate to the oxygen ion density, and that does not appear to be the case. Other processes, such as associative ionization, have also been proposed, but yields are uncertain because the reaction rates are very poorly known

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)

Measurement of Critical Contact Angle in a Microgravity Space Experiment

Science.gov (United States)

Concus, P.; Finn, R.; Weislogel, M.

1998-01-01

Mathematical theory predicts that small changes in container shape or in contact angle can give rise to large shifts of liquid in a microgravity environment. This phenomenon was investigated in the Interface Configuration Experiment on board the USMT,2 Space Shuttle flight. The experiment's "double proboscis" containers were designed to strike a balance between conflicting requirements of sizable volume of liquid shift (for ease of observation) and abruptness of the shift (for accurate determination of critical contact angle). The experimental results support the classical concept of macroscopic contact angle and demonstrate the role of hysteresis in impeding orientation toward equilibrium.

Fission reactor critical experiments and analysis

International Nuclear Information System (INIS)

Anon.

1977-01-01

Work accomplished in support of nonweapons programs by LASL Group Q-14 is described. Included are efforts in basic critical measurements, nuclear criticality safety, a plasma core critical assembly, and reactivity coefficient measurements

Forecast of criticality experiments and experimental programs needed to support nuclear operations in the United States of America: 1994-1999

International Nuclear Information System (INIS)

Rutherford, D.

1995-01-01

This Forecast is generated by the Chair of the Experiment Needs Identification Workgroup (ENIWG), with input from Department of Energy and the nuclear community. One of the current concerns addressed by ENIWG was the Defense Nuclear Facilities Safety Board's Recommendation 93-2. This Recommendation delineated the need for a critical experimental capability, which includes (1) a program of general-purpose experiments, (2) improving the information base, and (3) ongoing departmental programs. The nuclear community also recognizes the importance of criticality theory, which, as a stepping stone to computational analysis and safety code development, needs to be benchmarked against well-characterized critical experiments. A summary projection of the Department's needs with respect to criticality information includes (1) hands-on training, (2) criticality and nuclear data, (3) detector systems, (4) uranium- and plutonium-based reactors, and (5) accident analysis. The Workgroup has evaluated, prioritized, and categorized each proposed experiment and program. Transportation/Applications is a new category intended to cover the areas of storage, training, emergency response, and standards. This category has the highest number of priority-1 experiments (nine). Facilities capable of performing experiments include the Los Alamos Critical Experiment Facility (LACEF) along with Area V at Sandia National Laboratory. The LACEF continues to house the most significant collection of critical assemblies in the Western Hemisphere. The staff of this facility and Area V are trained and certified, and documentation is current. ENIWG will continue to work with the nuclear community to identify and prioritize experiments because there is an overwhelming need for critical experiments to be performed for basic research and code validation

Forecast of criticality experiments and experimental programs needed to support nuclear operations in the United States of America: 1994--1999

International Nuclear Information System (INIS)

Rutherford, D.

1994-03-01

This Forecast is generated by the Chair of the Experiment Needs Identification Workgroup (ENIWG), with input from Department of Energy and the nuclear community. One of the current concerns addressed by ENIWG was the Defense Nuclear Facilities Safety Board's Recommendation 93-2. This Recommendation delineated the need for a critical experimental capability, which includes (1) a program of general-purpose experiments, (2) improving the information base, and (3) ongoing departmental programs. The nuclear community also recognizes the importance of criticality theory, which, as a stepping stone to computational analysis and safety code development, needs to be benchmarked against well-characterized critical experiments. A summary project of the Department's needs with respect to criticality information includes (1) hands-on training, (2) criticality and nuclear data, (3) detector systems, (4) uranium- and plutonium-based reactors, and (5) accident analysis. The Workgroup has evaluated, prioritized, and categorized each proposed experiment and program. Transportation/Applications is a new category intended to cover the areas of storage, training, emergency response, and standards. This category has the highest number of priority-1 experiments (nine). Facilities capable of performing experiments include the Los Alamos Critical Experiment Facility (LACEF) along with Area V at Sandia National Laboratory. The LACEF continues to house the most significant collection of critical assemblies in the Western Hemisphere. The staff of this facility and Area V are trained and certified, and documentation is current. ENIWG will continue to work with the nuclear community to identify and prioritize experiments because there is an overwhelming need for critical experiments to be performed for basic research and code validation

Risk management for operations of the Los Alamos critical experiments facility

International Nuclear Information System (INIS)

Paternoster, R.; Butterfield, K.

1998-01-01

The Los Alamos Critical Experiments Facility (LACEF) currently operates two burst reactors (Godiva-IV and Skua), one solution assembly (SHEBA 2--Solution high-Energy Burst Assembly), two fast-spectrum benchmark assemblies (Flattop and Big Ten), and five general-purpose remote assembly machines which may be configured with nuclear materials and assembled by remote control. SNM storage vaults support these and other operations at the site. With this diverse set of operations, several approaches are possible in the analysis and management of risk. The most conservative approach would be to write a safety analysis report (SAR) for each assembly and experiment. A more cost-effective approach is to analyze the probability and consequences of several classes of operations representative of operations on each critical assembly machine and envelope the bounding case accidents. Although the neutron physics of these machines varies widely, the operations performed at LACEF fall into four operational modes: steady-state mode, approach-to-critical mode, prompt burst mode, and nuclear material operations which can include critical assembly fuel loading. The operational sequences of each mode are very nearly the same, whether operated on one assembly machine or another. The use of an envelope approach to accident analysis is facilitated by the use of classes of operations and the use of bounding case consequence analysis. A simple fault tree analysis of operational modes helps resolve which operations are sensitive to human error and which are initiated by hardware of software failures. Where possible, these errors and failures are blocked by TSR LCOs

Catalog and history of the experiments of criticality Saclay (1958-1964) Valduc / Building 10 (1964-2003)

International Nuclear Information System (INIS)

Poullot, G.; Dumont, V.; Anno, J.; Cousinou, P.; Grivot, P.; Girault, E.; Fouillaud, P.; Barbry, F.

2003-01-01

The group ' International Criticality Safety Evaluation Benchmark evaluation project ' (I.C.S.B.E.P.) has for aim to supply to the international community experiments of benchmarks criticality, of certified quality, used to guarantee the qualification of criticality calculation codes. Have been defined: a structure of experiments classification, a format of standard presentation, a structure of work with evaluation, internal and external checks, presentation in plenary session. After favourable opinion of the work group, the synthesis document called evaluation is integrated to the general report I.C.S.B.E.P. (N.C.)

Nurses’ Experiences of Managing and Management in a Critical Care Unit

Directory of Open Access Journals (Sweden)

K. Robyn Ogle

2014-05-01

Full Text Available In this article, we describe the major findings of an ethnographic study undertaken to investigate nurses’ experiences of managing nurses and being managed by nurses in an Australian critical care unit. Our purpose was to valorize and make space for nurses to speak of their experiences and investigate the cultural practices and knowledges that comprised nursing management discourses. Subjugated practices, knowledges, and discourses were identified, revealing how nurses were inscribed by, or resisted, the discourses, including their multiple mobile subject positions. Informed by critical, feminist, and postmodern perspectives, nine mobile subject positions were identified. Direct participant observation, participant interviews, and reflective field notes were analyzed for dominant and subjugated discourses. The major finding described is the subject position of “junior novice.” Nurses informed by dominant patriarchal and organizational discourses participated in constructing and reinscribing their own submissive identity reflected in interprofessional relations that lacked individual valuing and undermined their self-esteem.

Nurses’ Experiences of Managing and Management in a Critical Care Unit

Science.gov (United States)

Ogle, K. Robyn; Glass, Nel

2014-01-01

In this article, we describe the major findings of an ethnographic study undertaken to investigate nurses’ experiences of managing nurses and being managed by nurses in an Australian critical care unit. Our purpose was to valorize and make space for nurses to speak of their experiences and investigate the cultural practices and knowledges that comprised nursing management discourses. Subjugated practices, knowledges, and discourses were identified, revealing how nurses were inscribed by, or resisted, the discourses, including their multiple mobile subject positions. Informed by critical, feminist, and postmodern perspectives, nine mobile subject positions were identified. Direct participant observation, participant interviews, and reflective field notes were analyzed for dominant and subjugated discourses. The major finding described is the subject position of “junior novice.” Nurses informed by dominant patriarchal and organizational discourses participated in constructing and reinscribing their own submissive identity reflected in interprofessional relations that lacked individual valuing and undermined their self-esteem. PMID:28462287

Extrapolation of ZPR sodium void measurements to the power reactor

International Nuclear Information System (INIS)

Beck, C.L.; Collins, P.J.; Lineberry, M.J.; Grasseschi, G.L.

1976-01-01

Sodium-voiding measurements of ZPPR assemblies 2 and 5 are analyzed with ENDF/B Version IV data. Computations include directional diffusion coefficients to account for streaming effects resulting from the plate structure of the critical assembly. Bias factors for extrapolating critical assembly data to the CRBR design are derived from the results of this analysis

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

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)

Forecast of criticality experiments and experimental programs needed to support nuclear operations in the United States of America: 1994--1999

Energy Technology Data Exchange (ETDEWEB)

Rutherford, D.

1994-03-01

This Forecast is generated by the Chair of the Experiment Needs Identification Workgroup (ENIWG), with input from Department of Energy and the nuclear community. One of the current concerns addressed by ENIWG was the Defense Nuclear Facilities Safety Board`s Recommendation 93-2. This Recommendation delineated the need for a critical experimental capability, which includes (1) a program of general-purpose experiments, (2) improving the information base, and (3) ongoing departmental programs. The nuclear community also recognizes the importance of criticality theory, which, as a stepping stone to computational analysis and safety code development, needs to be benchmarked against well-characterized critical experiments. A summary project of the Department`s needs with respect to criticality information includes (1) hands-on training, (2) criticality and nuclear data, (3) detector systems, (4) uranium- and plutonium-based reactors, and (5) accident analysis. The Workgroup has evaluated, prioritized, and categorized each proposed experiment and program. Transportation/Applications is a new category intended to cover the areas of storage, training, emergency response, and standards. This category has the highest number of priority-1 experiments (nine). Facilities capable of performing experiments include the Los Alamos Critical Experiment Facility (LACEF) along with Area V at Sandia National Laboratory. The LACEF continues to house the most significant collection of critical assemblies in the Western Hemisphere. The staff of this facility and Area V are trained and certified, and documentation is current. ENIWG will continue to work with the nuclear community to identify and prioritize experiments because there is an overwhelming need for critical experiments to be performed for basic research and code validation.

Recalled peer relationship experiences and current levels of self-criticism and self-reassurance.

Science.gov (United States)

Kopala-Sibley, Daniel C; Zuroff, David C; Leybman, Michelle J; Hope, Nora

2013-03-01

Numerous studies have shown that personality factors may increase or decrease individuals' vulnerability to depression, but little research has examined the role of peer relationships in the development of these factors. Accordingly, this study examined the role of recalled parenting and peer experiences in the development of self-criticism and self-reassurance. It was hypothesized that, controlling for recalled parenting behaviours, specific recalled experiences of peer relationships would be related to current levels of specific forms of self-criticism and self-reassurance. Hypotheses were tested using a retrospective design in which participants were asked to recall experiences of parenting and peer relationships during early adolescence. This age was chosen as early adolescence has been shown to be a critical time for the development of vulnerability to depression. A total of 103 female and 97 male young adults completed measures of recalled parenting, overt and relational victimization and prosocial behaviour by peers, and current levels of self-criticism and self-reassurance. Hierarchical regression analyses showed that parents and peers independently contributed to the development of self-criticism and self-reassurance. Specifically, controlling for parental care and control, overt victimization predicted self-hating self-criticism, relational victimization predicted inadequacy self-criticism, and prosocial behaviour predicted self-reassurance. As well, prosocial behaviour buffered the effect of overt victimization on self-reassurance. Findings highlight the importance of peers in the development of personality risk and resiliency factors for depression, and suggest avenues for interventions to prevent the development of depressive vulnerabilities in youth. The nature of a patient's personality vulnerability to depression may be better understood through a consideration of the patient's relationships with their peers as well as with parents during

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

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

Development of An Embedded FPGA-Based Data Acquisition System Dedicated to Zero Power Reactor Noise Experiments

Directory of Open Access Journals (Sweden)

Arkani Mohammad

2014-08-01

Full Text Available An embedded time interval data acquisition system (DAS is developed for zero power reactor (ZPR noise experiments. The system is capable of measuring the correlation or probability distribution of a random process. The design is totally implemented on a single Field Programmable Gate Array (FPGA. The architecture is tested on different FPGA platforms with different speed grades and hardware resources. Generic experimental values for time resolution and inter-event dead time of the system are 2.22 ns and 6.67 ns respectively. The DAS can record around 48-bit x 790 kS/s utilizing its built-in fast memory. The system can measure very long time intervals due to its 48-bit timing structure design. As the architecture can work on a typical FPGA, this is a low cost experimental tool and needs little time to be established. In addition, revisions are easily possible through its reprogramming capability. The performance of the system is checked and verified experimentally.

Analysis of the impact of correlated benchmark experiments on the validation of codes for criticality safety analysis

International Nuclear Information System (INIS)

Bock, M.; Stuke, M.; Behler, M.

2013-01-01

The validation of a code for criticality safety analysis requires the recalculation of benchmark experiments. The selected benchmark experiments are chosen such that they have properties similar to the application case that has to be assessed. A common source of benchmark experiments is the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments' (ICSBEP Handbook) compiled by the 'International Criticality Safety Benchmark Evaluation Project' (ICSBEP). In order to take full advantage of the information provided by the individual benchmark descriptions for the application case, the recommended procedure is to perform an uncertainty analysis. The latter is based on the uncertainties of experimental results included in most of the benchmark descriptions. They can be performed by means of the Monte Carlo sampling technique. The consideration of uncertainties is also being introduced in the supplementary sheet of DIN 25478 'Application of computer codes in the assessment of criticality safety'. However, for a correct treatment of uncertainties taking into account the individual uncertainties of the benchmark experiments is insufficient. In addition, correlations between benchmark experiments have to be handled correctly. For example, these correlations can arise due to different cases of a benchmark experiment sharing the same components like fuel pins or fissile solutions. Thus, manufacturing tolerances of these components (e.g. diameter of the fuel pellets) have to be considered in a consistent manner in all cases of the benchmark experiment. At the 2012 meeting of the Expert Group on 'Uncertainty Analysis for Criticality Safety Assessment' (UACSA) of the OECD/NEA a benchmark proposal was outlined that aimed for the determination of the impact on benchmark correlations on the estimation of the computational bias of the neutron multiplication factor (k eff ). The analysis presented here is based on this proposal. (orig.)

Alecto, criticality experiment on a plutonium solution. Experimental results. Vessel number 1 (φ = 324 mm)

International Nuclear Information System (INIS)

Bruna, J.; Brunet, J.F.; Caizergues, R.; Clouet D'orval, C.; Kremser, J.; Leclerc, J.; Verriere, P.

1963-01-01

ALECTO is a critical experiment intended for the neutronic study of homogeneous aqueous multiplying media. It essentially consists of a cylindrical tank, reflected or not, where can be made critical a solution of fissionable material fed into the tank from a geometrically subcritical storage. The studies effected on this assembly concern on one hand the determination of critical masses, on the other hand the nuclear parameters used in neutron calculations. The container tested in the first series of experiments hereby described is a cylindrical tank, 324 mm diameter with a convex bottom, water reflected on the sides and on the inferior part. The minimum critical mass of this tank was determined and was found to be: M cmin = 845 ± 7 g. The decay constant of prompt neutrons as a function of reactivity was determined by the pulsed neutron technique. At the critical state, it was found to be: α c = 73 ± 6 s -1 . Furthermore, from the study of this tank, were derived a number of safety regulations for plutonium solutions. (authors) [fr

Calculated K-effectives using ENDF/B-V data for U + Pu solution critical experiments

International Nuclear Information System (INIS)

Primm, R.T. III; Mincey, J.F.

1981-01-01

Effective multiplication factors for 12 critical experiments have been calculated using multigroup cross sections derived from the ENDF/B-V library. All 12 experiments contained mixed plutonium and uranium nitrate solutions. The range of hydrogen-to-fissile plutonium atom ratios spanned by these experiments was 200 to 2200. A comparison with K-effectives calculated with ENDF/B-IV data is presented

Promotion of critical thinking in e-learning: a qualitative study on the experiences of instructors and students

Science.gov (United States)

Gharib, Mitra; Zolfaghari, Mitra; Mojtahedzadeh, Rita; Mohammadi, Aeen; Gharib, Atoosa

2016-01-01

Background With the increasing popularity of e-learning programs, educational stakeholders are attempting to promote critical thinking in the virtual education system. This study aimed to explore the experiences of both the instructors and the students about critical thinking promotion within the virtual education system. Methods This qualitative study recruited the instructors and students from four academic disciplines provided by the Virtual School of Tehran University of Medical Sciences (Tehran, Iran). All programs were master’s degree programs and utilized a blended (combination of e-learning and face to face) training. Semistructured interviews with the participants were used to collect data. Results The participants had a variety of experiences about how to promote critical thinking. These experiences were conceptualized in four main themes, namely, instructional design, educational leadership and management, local evidence, and belief systems. Conclusion The present study clarified the factors affecting critical thinking promotion in e-learning. Not only the instructors but also the educational designers and leaders can benefit from our findings to improve the quality of virtual education programs and promote critical thinking. PMID:27217807

Promotion of critical thinking in e-learning: a qualitative study on the experiences of instructors and students.

Science.gov (United States)

Gharib, Mitra; Zolfaghari, Mitra; Mojtahedzadeh, Rita; Mohammadi, Aeen; Gharib, Atoosa

2016-01-01

With the increasing popularity of e-learning programs, educational stakeholders are attempting to promote critical thinking in the virtual education system. This study aimed to explore the experiences of both the instructors and the students about critical thinking promotion within the virtual education system. This qualitative study recruited the instructors and students from four academic disciplines provided by the Virtual School of Tehran University of Medical Sciences (Tehran, Iran). All programs were master's degree programs and utilized a blended (combination of e-learning and face to face) training. Semistructured interviews with the participants were used to collect data. The participants had a variety of experiences about how to promote critical thinking. These experiences were conceptualized in four main themes, namely, instructional design, educational leadership and management, local evidence, and belief systems. The present study clarified the factors affecting critical thinking promotion in e-learning. Not only the instructors but also the educational designers and leaders can benefit from our findings to improve the quality of virtual education programs and promote critical thinking.

Critical experiment needs and plans of the consolidated fuel reprocessing program

International Nuclear Information System (INIS)

Primm, R.T.

1984-01-01

An integral part of the United States Department of Energy (DOE) plan for the development of breeder reactors is the development of the capability for fuel reprocessing. The Consolidated Fuel Reprocessing Program (CFRP) was established by the DOE to identify and conduct research and development activities in this area. The DOE is currently proposing that a capability to reprocess fast reactor fuel be established in the Fuels and Materials Examination Facility at the Hanford Engineering Development Laboratory. This capability would include conversion of plutonium nitrate to plutonium oxide. The reprocessing line is designated the Breeder Reprocessing Engineering Test (BRET). Criticality safety remains an important critetion in the design of the BRET. The different steps in the reprocessing are reviewed and areas where additional critical experiments are needed have been indentified as also areas where revision or clarification of existing criticality safety standards are desirable

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

NARCISS critical stand experiments for studying the nuclear safety in accident water immersion of highly enriched uranium dioxide fuel elements

International Nuclear Information System (INIS)

Ponomarev-Stepnoj, N.N.; Glushkov, E.S.; Bubelev, V.G.

2005-01-01

A brief description of the Topaz-2 SNPS designed under scientific supervision of RRC KI in Russia, and of the NARCISS critical facility, is given. At the NARCISS critical facility, neutronic peculiarities and nuclear safety issues of the Topaz-2 system reactor were studied experimentally. This work is devoted to a detailed description of experiments on investigation of criticality safety in accident water immersion og highly enriched uranium dioxide fuel elements, performed at the NARCISS facility. The experiments were carried out at water-moderated critical assemblies with varying height, number, and spacing of fuel elements. The results obtained in the critical experiments, computational models of the investigated critical configurations, and comparison of the computational and experimental results are given [ru

Controlled damping of a physical pendulum: experiments near critical conditions

International Nuclear Information System (INIS)

Gonzalez, Manuel I; Bol, Alfredo

2006-01-01

This paper presents an experimental device for the study of damped oscillatory motion along with three associated experiments. Special emphasis is given on both didactic aspects and the interactivity of the experimental set-up, in order to assist students in understanding fundamental aspects of damped oscillatory motion and allow them to directly compare their experimental results with the well-known theory they can find in textbooks. With this in mind, a physical pendulum was selected with an eddy-current damping system that allows the damping conditions to be controlled with great precision. The three experiments examine accurate control of damping, frequency shift near critical damping and the transition from underdamped to overdamped conditions

Complementary role of critical integral experiment and power reactor start-up experiments for LMFBR neutronics data and method validation

International Nuclear Information System (INIS)

Salvatores, M.

1986-09-01

Both critical experiments and power reactor results play at present a complementary role in reducing the uncertainties in Key design parameters for LMFBR, which can be relevant for the economic performances of this type of reactors

Modeling of critical experiments employing Raschig rings in uranyl nitrate solution

International Nuclear Information System (INIS)

Tanner, J.E.

1989-01-01

Four critical experiments employing borated glass rings in concentrated uranyl nitrate solution yielded k eff higher by 0. 04 when modeled with a flux-weighted, homogenized cross section set than when modeled with discrete rings. k eff varied by 0.014 for a 10% boron uncertainty and by up to 0.04 for a 10% packing fraction uncertainty

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.

A double concern: Grandmothers' experiences when a small grandchild is critically ill

DEFF Research Database (Denmark)

Hall, Elisabeth

2004-01-01

Grandmothers play an active part in family health and illness, but so far they are peripheral in both nursing and nursing research. This article addresses grandmothers' lived experiences when a small grandchild is critically ill. A convenience sample of 7 grandmothers was interviewed once...

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)

Analysis of kyoto university reactor physics critical experiments using NCNSRC calculation methodology

International Nuclear Information System (INIS)

Amin, E.; Hathout, A.M.; Shouman, S.

1997-01-01

The kyoto university reactor physics experiments on the university critical assembly is used to benchmark validate the NCNSRC calculations methodology. This methodology has two lines, diffusion and Monte Carlo. The diffusion line includes the codes WIMSD4 for cell calculations and the two dimensional diffusion code DIXY2 for core calculations. The transport line uses the MULTIKENO-Code vax Version. Analysis is performed for the criticality, and the temperature coefficients of reactivity (TCR) for the light water moderated and reflected cores, of the different cores utilized in the experiments. The results of both Eigen value and TCR approximately reproduced the experimental and theoretical Kyoto results. However, some conclusions are drawn about the adequacy of the standard wimsd4 library. This paper is an extension of the NCNSRC efforts to assess and validate computer tools and methods for both Et-R R-1 and Et-MMpr-2 research reactors. 7 figs., 1 tab

Critical experiments with 4.31 wt % 235U-enriched UO2 rods in highly borated water lattices

International Nuclear Information System (INIS)

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

1982-08-01

A series of critical experiments were performed with 4.31 wt % 235 U enriched UO 2 fuel rods immersed in water containing various concentrations of boron ranging up to 2.55 g/l. The boron was added in the form of boric acid (H 3 BO 3 ). Critical experimental data were obtained for two different lattice pitches wherein the water-to-uranium oxide volume ratios were 1.59 and 1.09. The experiments provide benchmarks on heavily borated systems for use in validating calculational techniques employed in analyzing fuel shipping casks and spent fuel storage systems that may utilize boron for criticality control

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.

In Planta Single-Molecule Pull-Down Reveals Tetrameric Stoichiometry of HD-ZIPIII:LITTLE ZIPPER Complexes.

Science.gov (United States)

Husbands, Aman Y; Aggarwal, Vasudha; Ha, Taekjip; Timmermans, Marja C P

2016-08-01

Deciphering complex biological processes markedly benefits from approaches that directly assess the underlying biomolecular interactions. Most commonly used approaches to monitor protein-protein interactions typically provide nonquantitative readouts that lack statistical power and do not yield information on the heterogeneity or stoichiometry of protein complexes. Single-molecule pull-down (SiMPull) uses single-molecule fluorescence detection to mitigate these disadvantages and can quantitatively interrogate interactions between proteins and other compounds, such as nucleic acids, small molecule ligands, and lipids. Here, we establish SiMPull in plants using the HOMEODOMAIN LEUCINE ZIPPER III (HD-ZIPIII) and LITTLE ZIPPER (ZPR) interaction as proof-of-principle. Colocalization analysis of fluorophore-tagged HD-ZIPIII and ZPR proteins provides strong statistical evidence of complex formation. In addition, we use SiMPull to directly quantify YFP and mCherry maturation probabilities, showing these differ substantially from values obtained in mammalian systems. Leveraging these probabilities, in conjunction with fluorophore photobleaching assays on over 2000 individual complexes, we determined HD-ZIPIII:ZPR stoichiometry. Intriguingly, these complexes appear as heterotetramers, comprising two HD-ZIPIII and two ZPR molecules, rather than heterodimers as described in the current model. This surprising result raises new questions about the regulation of these key developmental factors and is illustrative of the unique contribution SiMPull is poised to make to in planta protein interaction studies. © 2016 American Society of Plant Biologists. All rights reserved.

Microcomputer-based equipment-control and data-acquisition system for fission-reactor reactivity-worth measurements

International Nuclear Information System (INIS)

McDowell, W.P.; Bucher, R.G.

1980-01-01

Material reactivity-worth measurements are one of the major classes of experiments conducted on the Zero Power research reactors (ZPR) at Argonne National Laboratory. These measurements require the monitoring of the position of a servo control element as a sample material is positioned at various locations in a critical reactor configuration. In order to guarantee operational reliability and increase experimental flexibility for these measurements, the obsolete hardware-based control unit has been replaced with a microcomputer based equipment control and data acquisition system. This system is based on an S-100 bus, dual floppy disk computer with custom built cards to interface with the experimental system. To measure reactivity worths, the system accurately positions samples in the reactor core and acquires data on the position of the servo control element. The data are then analyzed to determine statistical adequacy. The paper covers both the hardware and software aspects of the design

Microcomputer-based equipment-control and data-acquisition system for fission-reactor reactivity-worth measurements

Energy Technology Data Exchange (ETDEWEB)

McDowell, W.P.; Bucher, R.G.

1980-01-01

Material reactivity-worth measurements are one of the major classes of experiments conducted on the Zero Power research reactors (ZPR) at Argonne National Laboratory. These measurements require the monitoring of the position of a servo control element as a sample material is positioned at various locations in a critical reactor configuration. In order to guarantee operational reliability and increase experimental flexibility for these measurements, the obsolete hardware-based control unit has been replaced with a microcomputer based equipment control and data acquisition system. This system is based on an S-100 bus, dual floppy disk computer with custom built cards to interface with the experimental system. To measure reactivity worths, the system accurately positions samples in the reactor core and acquires data on the position of the servo control element. The data are then analyzed to determine statistical adequacy. The paper covers both the hardware and software aspects of the design.

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.

The Experience of Critical Self-Reflection by Life Coaches: A Phenomenological Study

Science.gov (United States)

Shaw, Deanna Lynn

2012-01-01

The purpose of this study was to describe the experience of critical self-reflection by life coaches. Life coaching is expanding within many disciplines including education, health care, business, social work, and wellness. Life coaching involves a coach working with an individual or groups aimed at effecting change for professional and personal…

Safety analysis report for the Hanford Critical Mass Laboratory: Supplement No. 2. Experiments with heterogeneous assemblies

International Nuclear Information System (INIS)

Gore, B.F.; Davenport, L.C.

1981-04-01

Factors affecting the safety of criticality experiments using heterogeneous assemblies are described and assessed. It is concluded that there is no substantial change in safety from experiments already being routinely performed at the Critical Mass Laboratory (CML), and that laboratory and personnel safety are adequately provided by the combination of engineered and administrative safety limits enforced at the CML. This conclusion is based on the analysis of operational controls, potential hazards, and the consequences of accidents. Contingencies considered that could affect nuclear criticality include manual changes in fuel loadings, water flooding, fire, explosion, loss of services, earthquake, windstorm, and flood. Other potential hazards considered include radiation exposure to personnel, and potential releases within the Assembly Room and outside to the environment. It is concluded that the Maximum Credible Nuclear Burst of 3 x 10 18 fissions (which served as the design basis for the CML) is valid for heterogeneous assemblies as well as homogeneous assemblies. This is based upon examination of the results of reactor destructive tests and the results of the SL-1 reactor destructive accident. The production of blast effects which might jeopardize the CML critical assembly room (of thick reinforced concrete) is not considered credible due to the extreme circumstances required to produce blast effects in reactor destructive tests. Consequently, it is concluded that, for experiments with heterogeneous assemblies, the consequences of the Maximum Credible Burst are unchanged from those previously estimated for experiments with homogeneous systems

Criticality safety benchmark experiment on 10% enriched uranyl nitrate solution using a 28-cm-thickness slab core

International Nuclear Information System (INIS)

Yamamoto, Toshihiro; Miyoshi, Yoshinori; Kikuchi, Tsukasa; Watanabe, Shouichi

2002-01-01

The second series of critical experiments with 10% enriched uranyl nitrate solution using 28-cm-thick slab core have been performed with the Static Experiment Critical Facility of the Japan Atomic Energy Research Institute. Systematic critical data were obtained by changing the uranium concentration of the fuel solution from 464 to 300 gU/l under various reflector conditions. In this paper, the thirteen critical configurations for water-reflected cores and unreflected cores are identified and evaluated. The effects of uncertainties in the experimental data on k eff are quantified by sensitivity studies. Benchmark model specifications that are necessary to construct a calculational model are given. The uncertainties of k eff 's included in the benchmark model specifications are approximately 0.1%Δk eff . The thirteen critical configurations are judged to be acceptable benchmark data. Using the benchmark model specifications, sample calculation results are provided with several sets of standard codes and cross section data. (author)

Methods and approaches to provide feedback from nuclear and covariance data adjustment for improvement of nuclear data files. SG39 meeting, November 2014

International Nuclear Information System (INIS)

Aufiero, Manuele; Ivanov, Evgeny; Hoefer, Axel; Yokoyama, Kenji; Da Cruz, Dirceu Ferreira; KODELI, Ivan-Alexander; Hursin, Mathieu; Pelloni, Sandro; Palmiotti, Giuseppe; Salvatores, Massimo; Barnes, Andrew; Cabellos De Francisco, Oscar; ); Ivanova, Tatiana; )

2014-11-01

The aim of WPEC subgroup 39 'Methods and approaches to provide feedback from nuclear and covariance data adjustment for improvement of nuclear data files' is to provide criteria and practical approaches to use effectively the results of sensitivity analyses and cross section adjustments for feedback to evaluators and differential measurement experimentalists in order to improve the knowledge of neutron cross sections, uncertainties, and correlations to be used in a wide range of applications. This document is the proceedings of the third formal Subgroup meeting held at the NEA, Issy-les-Moulineaux, France, on 27-28 November 2014. It comprises a Summary Record of the meeting and all the available presentations (slides) given by the participants: A - Sensitivity methods: 1 - Perturbation/sensitivity calculations with Serpent (M. Aufiero); 2 - Comparison of deterministic and Monte Carlo sensitivity analysis of SNEAK-7A and FLATTOP-Pu Benchmarks (I. Kodeli); B - Integral experiments: 1 - PROTEUS experiments: selected experiments sensitivity profiles and availability, (M. Hursin, M. Salvatores - PROTEUS Experiments, HCLWR configurations); 2 - SINBAD Benchmark Database and FNS/JAEA Liquid Oxygen TOF Experiment Analysis (I. Kodeli); 3 - STEK experiment Opportunity for Validation of Fission Products Nuclear Data (D. Da Cruz); 4 - SEG (tailored adjoint flux shapes) (M. Savatores - comments) 5 - IPPE transmission experiments (Fe, 238 U) (T. Ivanova); 6 - RPI semi-integral (Fe, 238 U) (G. Palmiotti - comments); 7 - New experiments, e.g. in connection with the new NSC Expert Group on 'Improvement of Integral Experiments Data for Minor Actinide Management' (G. Palmiotti - Some comments from the Expert Group) 8 - Additional PSI adjustment studies accounting for nonlinearity (S. Pelloni); 9 - Adjustment methodology issues (G. Palmiotti); C - Am-241 and fission product issues: 1 - Am-241 validation for criticality-safety calculations (A. Barnes - Visio

Water/sand flooded and immersed critical experiment and analysis performed in support of the TOPAZ-II Safety Program

International Nuclear Information System (INIS)

Glushkov, E.S.; Ponomarev-Stepnoi, N.N.; Bubelev, V.G.; Garin, V.P.; Gomin, E.A.; Kompanietz, G.V.; Krutoy, A.M.; Lobynstev, V.A.; Maiorov, L.V.; Polyakov, D.N.

1994-01-01

Presented is a brief description of the Narciss-M2 critical assemblies, which simulate accidental water/wet-sand immersion of the TOPAZ-II reactor as well as water-flooding of core cavities. Experimental results obtained from these critical assemblies, including experiments with several fuel elements removed from the core, are shown. These configurations with several extracted fuel elements simulate a proposed fuel-out anticriticality-device modification to the TOPAZ-II reactor. Preliminary computational analysis of these experiments using the Monte Carlo neutron-transport method is outlined. Nuclear criticality safety of the TOPAZ-II reactor with an incorporated anticriticality unit is demonstrated

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

MCNP benchmark analyses of critical experiments for the Space Nuclear Thermal Propulsion program

International Nuclear Information System (INIS)

Selcow, E.C.; Cerbone, R.J.; Ludewig, H.; Mughabghab, S.F.; Schmidt, E.; Todosow, M.; Parma, E.J.; Ball, R.M.; Hoovler, G.S.

1993-01-01

Benchmark analyses have been performed of Particle Bed Reactor (PBR) critical experiments (CX) using the MCNP radiation transport code. The experiments have been conducted at the Sandia National Laboratory reactor facility in support of the Space Nuclear Thermal Propulsion (SNTP) program. The test reactor is a nineteen element water moderated and reflected thermal system. A series of integral experiments have been carried out to test the capabilities of the radiation transport codes to predict the performance of PBR systems. MCNP was selected as the preferred radiation analysis tool for the benchmark experiments. Comparison between experimental and calculational results indicate close agreement. This paper describes the analyses of benchmark experiments designed to quantify the accuracy of the MCNP radiation transport code for predicting the performance characteristics of PBR reactors

MCNP benchmark analyses of critical experiments for the Space Nuclear Thermal Propulsion program

Science.gov (United States)

Selcow, Elizabeth C.; Cerbone, Ralph J.; Ludewig, Hans; Mughabghab, Said F.; Schmidt, Eldon; Todosow, Michael; Parma, Edward J.; Ball, Russell M.; Hoovler, Gary S.

1993-01-01

Benchmark analyses have been performed of Particle Bed Reactor (PBR) critical experiments (CX) using the MCNP radiation transport code. The experiments have been conducted at the Sandia National Laboratory reactor facility in support of the Space Nuclear Thermal Propulsion (SNTP) program. The test reactor is a nineteen element water moderated and reflected thermal system. A series of integral experiments have been carried out to test the capabilities of the radiation transport codes to predict the performance of PBR systems. MCNP was selected as the preferred radiation analysis tool for the benchmark experiments. Comparison between experimental and calculational results indicate close agreement. This paper describes the analyses of benchmark experiments designed to quantify the accuracy of the MCNP radiation transport code for predicting the performance characteristics of PBR reactors.

The Relationship between College Experience at a Historically Black College and Students' Critical Thinking Skills

Science.gov (United States)

Little, Irene Pruitt

2017-01-01

The purpose of this quantitative correlational study was to examine the relationship between college experience at a HBCU and students' critical thinking skills. The theoretical framework included Astin's theory of involvement and Facione's taxonomy of critical thinking. The research site was a private four-year HBCU in the state of Alabama. The…

FLUOLE-2: An Experiment for PWR Pressure Vessel Surveillance

Directory of Open Access Journals (Sweden)

Thiollay Nicolas

2016-01-01

Full Text Available FLUOLE-2 is a benchmark-type experiment dedicated to 900 and 1450 MWe PWR vessels surveillance dosimetry. This two-year program started in 2014 and will end in 2015. It will provide precise experimental data for the validation of the neutron spectrum propagation calculation from core to vessel. It is composed of a square core surrounded by a stainless steel baffe and internals: PWR barrel is simulated by steel structures leading to different steel-water slides; two steel components stand for a surveillance capsule holder and for a part of the pressure vessel. Measurement locations are available on the whole experimental structure. The experimental knowledge of core sources will be obtained by integral gamma scanning measurements directly on fuel pins. Reaction rates measured by calibrated fission chambers and a large set of dosimeters will give information on the neutron energy and spatial distributions. Due to the low level neutron flux of EOLE ZPR a special, high efficiency, calibrated gamma spectrometry device will be used for some dosimeters, allowing to measure an activity as low as 7. 10−2 Bq per sample. 103mRh activities will be measured on an absolute calibrated X spectrometry device. FLUOLE-2 experiment goal is to usefully complete the current experimental benchmarks database used for the validation of neutron calculation codes. This two-year program completes the initial FLUOLE program held in 2006–2007 in a geometry representative of 1300 MWe PWR.

Critical heat-flux experiments under low-flow conditions in a vertical annulus

International Nuclear Information System (INIS)

Mishima, K.; Ishii, M.

1982-03-01

An experimental study was performed on critical heat flux (CHF) at low flow conditions for low pressure steam-water upward flow in an annulus. The test section was transparent, therefore, visual observations of dryout as well as various instrumentations were made. The data indicated that a premature CHF occurred due to flow regime transition from churn-turbulent to annular flow. It is shown that the critical heat flux observed in the experiment is essentially similar to a flooding-limited burnout and the critical heat flux can be well reproduced by a nondimensional correlation derived from the previously obtained criterion for flow regime transition. The observed CHF values are much smaller than the standard high quality CHF criteria at low flow, corresponding to the annular flow film dryout. This result is very significant, because the coolability of a heater surface at low flow rates can be drastically reduced by the occurrence of this mode of CHF

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

Nuclear criticality safety experiments, calculations, and analyses: 1958 to 1982. Volume 1. Lookup tables

International Nuclear Information System (INIS)

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

1982-01-01

This compilation contains 688 complete summaries of papers on nuclear criticality safety as presented at meetings of the American Nuclear Society (ANS). The selected papers contain criticality parameters for fissile materials derived from experiments and calculations, as well as criticality safety analyses for fissile material processing, transport, and storage. The compilation was developed as a component of the Nuclear Criticality Information System (NCIS) now under development at the Lawrence Livermore National Laboratory. The compilation is presented in two volumes: Volume 1 contains a directory to the ANS Transaction volume and page number where each summary was originally published, the author concordance, and the subject concordance derived from the keyphrases in titles. Volume 2 contains - in chronological order - the full-text summaries, reproduced here by permission of the American Nuclear Society from their Transactions, volumes 1-41

Re-evaluation of the criticality experiments of the ''Otto Hahn Nuclear Ship'' reactor

Energy Technology Data Exchange (ETDEWEB)

Lengar, I.; Snoj, L.; Rogan, P.; Ravnik, M. [Jozef Stefan Institute, Ljubljana (Slovenia)

2008-11-15

Several series of experiments with a FDR reactor (advanced pressurized light water reactor) were performed in 1972 in the Geesthacht critical facility ANEX. The experiments were performed to test the core prior to its usage for the propulsion of the first German nuclear merchant ship ''Otto-Hahn''. In the present paper a calculational re-evaluation of the experiments is described with the use of the up-to date computer codes (Monte-Carlo code MCNP5) and nuclear data (ENDF/B-VI release 6). It is focused on the determination of uncertainties in the benchmark model of the experimental set-up, originating mainly from the limited set of information still available about the experiments. Effects of the identified uncertainties on the multiplication factor were studied. The sensitivity studies include parametric variation of material composition and geometry. The combined total uncertainty being found 0.0050 in k{sub eff}, the experiments are qualified as criticality safety benchmark experiments. (orig.)

Validation of the ABBN/CONSYST constants system. Part 1: Validation through the critical experiments on compact metallic cores

International Nuclear Information System (INIS)

Ivanova, T.T.; Manturov, G.N.; Nikolaev, M.N.; Rozhikhin, E.V.; Semenov, M.Yu.; Tsiboulia, A.M.

1999-01-01

Worldwide compilation of criticality safety benchmark experiments, evaluated due to an activity of the International Criticality Safety Benchmark Evaluation Project (ICSBEP), discovers new possibilities for validation of the ABBN-93.1 cross section library for criticality safety analysis. Results of calculations of small assemblies with metal-fuelled cores are presented in this paper. It is concluded that ABBN-93.1 predicts criticality of such systems with required accuracy

Water/sand flooded and immersed critical experiment and analysis performed in support of the TOPAZ-II safety program

International Nuclear Information System (INIS)

Glushkov, E.S.; Ponomarev-Stepnoi, N.N.; Bubelev, V.G.; Garin, V.P.; Gomin, E.A.; Kompanietz, G.V.; Krutov, A.M.; Lobynstev, V.A.; Maiorov, L.V.; Polyakov, D.N.; Chunyaev, E.I.; Marshall, A.C.; Sapir, J.L.; Pelowitz, D.B.

1995-01-01

Presented is a brief description of the Narciss-M2 critical assemblies, which simulate accidental water/wet-sand immersion of the TOPAZ-II reactor as well as water-flooding of core cavities. Experimental results obtained from these critical assemblies, including experiments with several fuel elements removed from the core, are shown. These configurations with several extracted fuel elements simulate a proposed fuel-out anticriticality-device modification to the TOPAZ-II reactor. Preliminary computational analysis of these experiments using the Monte Carlo neutron-transport method is outlined. Nuclear criticality safety of the TOPAZ-II reactor with an incorporated anticriticality unit is demonstrated. copyright 1995 American Institute of Physics

Knowledge, Skills and Experience Managing Tracheostomy Emergencies: A Survey of Critical Care Medicine trainees

LENUS (Irish Health Repository)

Nizam, AA

2016-10-01

Since the development of percutaneous tracheostomy, the number of tracheostomy patients on hospital wards has increased. Problems associated with adequate tracheostomy care on the wards are well documented, particularly the management of tracheostomy-related emergencies. A survey was conducted among non-consultant hospital doctors (NCHDs) starting their Critical Care Medicine training rotation in a university affiliated teaching hospital to determine their basic knowledge and skills in dealing with tracheostomy emergencies. Trainees who had received specific tracheostomy training or who had previous experience of dealing with tracheostomy emergencies were more confident in dealing with such emergencies compared to trainees without such training or experience. Only a minority of trainees were aware of local hospital guidelines regarding tracheostomy care. Our results highlight the importance of increased awareness of tracheostomy emergencies and the importance of specific training for Anaesthesia and Critical Care Medicine trainees.

SN transport analyses of critical reactor experiments for the SNTP program

International Nuclear Information System (INIS)

Mays, C.W.

1993-01-01

The capability of S N methodology to accurately predict the neutronics behavior of a compact, light water-moderated reactor is examined. This includes examining the effects of cross-section modeling and the choice of spatial and angular representation. The isothermal temperature coefficient in the range of 293 K to 355 K is analyzed, as well as the radial fission density profile across the central fuel element. Measured data from a series of critical experiments are used for these analyses

Time-Critical Database Conditions Data-Handling for the CMS Experiment

CERN Document Server

De Gruttola, M; Innocente, V; Pierro, A

2011-01-01

Automatic, synchronous and of course reliable population of the condition database is critical for the correct operation of the online selection as well as of the offline reconstruction and data analysis. We will describe here the system put in place in the CMS experiment to automate the processes to populate centrally the database and make condition data promptly available both online for the high-level trigger and offline for reconstruction. The data are ``dropped{''} by the users in a dedicated service which synchronizes them and takes care of writing them into the online database. Then they are automatically streamed to the offline database, hence immediately accessible offline worldwide. This mechanism was intensively used during 2008 and 2009 operation with cosmic ray challenges and first LHC collision data, and many improvements were done so far. The experience of this first years of operation will be discussed in detail.

Professorial Views of the Use of Diversity Experiences to Develop Students' Critical Thinking Skills in the Pakistani College Context

Science.gov (United States)

Tahir, Khazima

2017-01-01

This study explored the interplay of diversity experiences and critical thinking of Pakistani college students and determined how the classroom experience supported and exposed students to diversity and critical thinking. The researcher conducted teachers' interviews to gather data in a college in Pakistan. Teachers were asked to respond to a…

Clinical accompaniment: the critical care nursing students’ experiences in a private hospital

Directory of Open Access Journals (Sweden)

N. Tsele

2000-09-01

Full Text Available The quality of clinical accompaniment of the student enrolled for the post-basic diploma in Medical and Surgical Nursing Science: Critical Care Nursing (General is an important dimension of the educational/learning programme. The clinical accompanist/mentor is responsible for ensuring the student’s compliance with the clinical outcomes of the programme in accordance with the requirements laid down by the Nursing Education Institution and the South African Nursing Council. The purpose of this study was to explore and describe the experiences of the students enrolled for a post-basic diploma in Medical and Surgical Nursing Science: Critical Care Nursing (General, in relation to the clinical accompaniment in a private hospital in Gauteng. An exploratory, descriptive and phenomenological research design was utilised and individual interviews were conducted with the ten students in the research hospital. A content analysis was conducted and the results revealed both positive and negative experiences by the students in the internal and external worlds. The recommendations include the formulation of standards for clinical accompaniment of students. the evaluation of the quality of clinical accompaniment of students and empowerment of the organisation, clinical accompanists/mentors and clinicians.

Safety evaluation report related to the renewal of the operating license for the Zero-Power Reactor at Cornell University, Docket No. 50-97

International Nuclear Information System (INIS)

1983-09-01

This Safety Evaluation Report for the application filed by Cornell University (CU) for a renewal of Operating License R-80 to continue to operate a zero-power reactor (ZPR) has been prepared by the Office of Nuclear Reactor Regulation of the US Nuclear Regulatory Commission. The facility is owned and operated by Cornell University and is located on the Cornell campus in Ithaca, New York. The staff concludes that the ZPR facility can continue to be operated by CU without endangering the health and safety of the public

Criticality experiments to provide benchmark data on neutron flux traps

International Nuclear Information System (INIS)

Bierman, S.R.

1988-06-01

The experimental measurements covered by this report were designed to provide benchmark type data on water moderated LWR type fuel arrays containing neutron flux traps. The experiments were performed at the US Department of Energy Hanford Critical Mass Laboratory, operated by Pacific Northwest Laboratory. The experimental assemblies consisted of 2 /times/ 2 arrays of 4.31 wt % 235 U enriched UO 2 fuel rods, uniformly arranged in water on a 1.891 cm square center-to-center spacing. Neutron flux traps were created between the fuel units using metal plates containing varying amounts of boron. Measurements were made to determine the effect that boron loading and distance between the fuel and flux trap had on the amount of fuel required for criticality. Also, measurements were made, using the pulse neutron source technique, to determine the effect of boron loading on the effective neutron multiplications constant. On two assemblies, reaction rate measurements were made using solid state track recorders to determine absolute fission rates in 235 U and 238 U. 14 refs., 12 figs., 7 tabs

Daptomycin experience in critical care patients: results from a registry.

Science.gov (United States)

Brown, Jack E; Fominaya, Cory; Christensen, Keith J; McConnell, Scott A; Lamp, Kenneth C

2012-04-01

Vancomycin is often the drug of choice in critically ill patients with gram-positive infections, although circumstances often prevent its use. In these situations, clinicians are frequently left with limited data regarding alternative agents. To describe patients with reported sepsis receiving daptomycin in a critical care unit. This multicenter, noncomparative, noninterventional study identified patients in critical care units, using the Cubicin Outcomes Registry and Experience (CORE) 2005-2009 registry. A descriptive account of patient characteristics, infectious etiology, outcomes at the end of daptomycin therapy, and 30-day mortality is reported. Nonevaluable patients were excluded from the efficacy analysis but included in the safety analysis. We identified 128 patients, 98 (77%) of whom were evaluable for efficacy. Patient characteristics for the efficacy population were 55 (56%) males, 30 (31%) aged 66 years or older, 38 (39%) had creatinine clearance less than 30 mL/min, and 27 (28%) were on dialysis. Common underlying diseases included acute or chronic renal failure 44 (45%), hypertension 40 (41%), and diabetes 27 (28%). Seventy-two (73%) patients were bacteremic. The most common pathogens found were methicillin-resistant Staphylococcus aureus (32%), vancomycin-resistant Enterococcus faecium (21%), and coagulase-negative staphylococci (20%). Prior to daptomycin, antibiotics were used in 84 (86%) patients, most commonly vancomycin (65/84; 77%). The median (range) initial daptomycin dose was 6 mg/kg (3-10) and duration of 10 days (1-58). Overall success rate was 70% (31% cured; 39% improved). Twelve adverse events possibly related to daptomycin were reported in 9 of 128 (7%) patients in the safety population; 4 of these in 4 (3%) patients were serious. The mortality rate within 30 days of completing daptomycin was 42 of 128 (33%) patients. These data provide preliminary results on the use of daptomycin in critically ill patients with complicated conditions

An investigation of emotion experiences at work : a critical incident technique approach / Natalie Booth

OpenAIRE

Booth, Natalie

2013-01-01

Orientation: Emotions at work have been considered as an important facet of employees’ work life. However, research regarding the investigation of the emotion experiences at work per se has been lacking. Research Purpose: The general objective of this study is to critically investigate what emotion events are experienced and how these events are appraised for them to result in specific emotions. Motivation for the study: Currently a lack of research regarding emotion experiences as a pr...

Validation of Cross Sections with Criticality Experiment and Reaction Rates: the Neptunium Case

CERN Document Server

Leong, L S; Audouin, L; Berthier, B; Le Naour, C; Stéphan, C; Paradela, C; Tarrío, D; Duran, I

2014-01-01

The Np-237 neutron-induced fission cross section has been recently measured in a large energy range (from eV to GeV) at the n\\_TOF facility at CERN. When compared to previous measurements the n\\_TOF fission cross section appears to be higher by 5-7\\% beyond the fission threshold. To check the relevance of the n\\_TOF data, we considered a criticality experiment performed at Los Alamos with a 6 kg sphere of Np-237, surrounded by uranium highly enriched in U-235 so as to approach criticality with fast neutrons. The multiplication factor k(eff) of the calculation is in better agreement with the experiment when we replace the ENDF/B-VII. 0 evaluation of the Np-237 fission cross section by the n\\_TOF data. We also explored the hypothesis of deficiencies of the inelastic cross section in U-235 which has been invoked by some authors to explain the deviation of 750 pcm. The large modification needed to reduce the deviation seems to be incompatible with existing inelastic cross section measurements. Also we show that t...

Analysis of selected critical experiments using ENDF/B-IV and ENDF/B-V data

International Nuclear Information System (INIS)

Crump, M.W.; Durston, C.; Jonsson, A.; Singh, U.N.

1983-01-01

Selected critical experiments were analyzed using ENDF/B-V data and results compared with measured parameters and with values obtained using ENDF/B-IV. The TRX-1 and -2 U-metal criticals were reanalyzed using ENDF/B-V with consistent multilevel processing of U-238 resonance data and increased spatial detail in the resonance slowing down calculations. The improved resonance treatment was applied in TRX cell calculations performed with the DIT code, and resulted in reduced predictions of U-238 capture by more than two percent relative to previous calculations. The results of the TRX analyses using ENDF/B-V indicate calculated rho 28 values 2 to 3% higher than measurements, and are found in overall agreement with results reported by other laboratories. Full core calculations for the TRX criticals were performed with the ANISN code using cross sections obtained from DIT core-reflector lattice calculations. An evaluation of core versus cell calculations for these criticals indicates differences corresponding to about one half percent in predicted reactivity

Consumer Electronics Processors for Critical Real-Time Systems: a (Failed) Practical Experience

OpenAIRE

Fernandez , Gabriel; Cazorla , Francisco; Abella , Jaume

2018-01-01

International audience; The convergence between consumer electronics and critical real-time markets has increased the need for hardware platforms able to deliver high performance as well as high (sustainable) performance guarantees. Using the ARM big.LITTLE architecture as example of those platforms, in this paper we report our experience with one of its implementations (the Qualcomm SnapDragon 810 processor) to derive performance bounds with measurement-based techniques. Our theoretical and ...

Pathways and pipelines: Self-reported critical experiences for expert and novice geologists

Science.gov (United States)

LaDue, N.; Pacheco, H. A.

2011-12-01

The recruitment and retention of geology students has received attention due to pressure from industry to replenish an aging workforce nearing retirement (Gonzales and Keane, 2010). Thorough, qualitative studies have been conducted using critical incident methodology to understand what experiences cause various groups of people to choose careers in the geosciences or geoscience degree programs (Levine et al., 2007; Houlton, 2010). This study both builds upon earlier studies and provides new insights about capacity building in the geosciences. Individuals who have been successfully pipelined into the geosciences ranging from upper-level undergraduates to decades-long professionals, were selected for an expert-novice study about field mapping. All of the 38 participants have field-mapping experience and were selected to achieve a balance of age, gender and experience in the sample and secondarily based on geographic diversity. Participants were asked how they became interested in geology as the last question of an interview about the other tasks during the study. Participants were surficially probed, in contrast to in-depth interviews conducted using critical incident methods. Remarkably, though the interview question was unstructured and open ended, the three persistent themes that emerged are consistent with previous studies of women geologists (Holmes and O'Connell, 2003), under-represented minorities (Levine et al., 2007), and undergraduate geoscience majors (Houlton, 2010): Role or influence of academic experience, influence of and/or connections with people and connections with Earth. Additionally, individual participant comments are well aligned the proposed framework by Kraft et al. (2011) for engaging geoscience students through the affective domain. We suggest that future studies should examine whether these findings are consistent across geologists from sub-domains that are less field-based and involve primarily modeling, or other computer- and lab

Experiences of Vulnerable Residential Customer Subpopulations with Critical Peak Pricing

Energy Technology Data Exchange (ETDEWEB)

Cappers, Peter [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Spurlock, C. Anna [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Todd, Annika [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Jin, Ling [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2017-04-13

DOE decided to co-fund ten utilities to undertake eleven experimentally-designed Consumer Behavior Studies (CBS) that proposed to examine a wide range of the topics of interest to the electric utility industry. Each chosen utility was to design, implement and evaluate their own study in order to address questions of interest both to itself and to its applicable regulatory authority, whose approval was generally necessary for the study to proceed. The DOE Office of Energy Delivery and Electricity Reliability (OE), however, did set guidelines, both in the FOA and subsequently during the contracting period, for what would constitute an acceptable study under the Grant. To assist in ensuring these guidelines were adhered to, OE requested that LBNL act as project manager for these Consumer Behavior Studies to achieve consistency of experimental design and adherence to data collection and reporting protocols across the ten utilities. As part of its role, LBNL formed technical advisory groups (TAG) to separately assist each of the utilities by providing technical assistance in all aspects of the design, implementation and evaluation of their studies. LBNL was also given a unique opportunity to perform a comprehensive, cross-study analysis that uses the customer-level interval meter and demographic data made available by these utilities due to SGIG-imposed reporting requirements, in order to analyze critical policy issues associated with AMI-enabled rates and control/information technology. LBNL will publish the results of these analyses in a series of research reports, of which this is one, that attempt to address critical policy issues relating to a variety of topics including customer acceptance, retention and load response to time-based rates and various forms of enabling control and information technologies. This report extends the existing empirical literature on the experiences of low-income customers exposed to critical peak pricing, and provides the first glimpses

Thinking Critically about Critical Thinking: Integrating Online Tools to Promote Critical Thinking

OpenAIRE

B. Jean Mandernach, PhD

2006-01-01

The value and importance of critical thinking is clearly established; the challenge for instructors lies in successfully promoting students’ critical thinking skills within the confines of a traditional classroom experience. Since instructors are faced with limited student contact time to meet their instructional objectives and facilitate learning, they are often forced to make instructional decisions between content coverage, depth of understanding, and critical analysis of course material. ...

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

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

Calculational study of benchmark critical experiments on high-enriched uranyl nitrate solution systems

International Nuclear Information System (INIS)

Oh, I.; Rothe, R.E.

1978-01-01

Criticality calculations on minimally reflected, concrete-reflected, and plastic-reflected single tanks and on arrays of cylinders reflected by concrete and plastic have been performed using the KENO-IV code with 16-group Hansen-Roach neutron cross sections. The fissile material was high-enriched (93.17% 235 U) uranyl nitrate [UO 2 (NO 3 ) 2 ] solution. Calculated results are compared with those from a benchmark critical experiments program to provide the best possible verification of the calculational technique. The calculated k/sub eff/'s underestimate the critical condition by an average of 1.28% for the minimally reflected single tanks, 1.09% for the concrete-reflected single tanks, 0.60% for the plastic-reflected single tanks, 0.75% for the concrete-reflected arrays of cylinders, and 0.51% for the plastic-reflected arrays of cylinders. More than half of the present comparisons were within 1% of the experimental values, and the worst calculational and experimental discrepancy was 2.3% in k/sub eff/ for the KENO calculations

Optical observations on the CRIT-II Critical Ionization Velocity Experiment

International Nuclear Information System (INIS)

Stenbaek-Nielsen, H.C.; Wescott, E.M.; Haerendel, G.; Valenzuela, A.

1990-01-01

A rocket borne Critical Ionization Velocity (CIV) experiment was carried out from Wallops Island at dusk on May 4, 1989. Two barium shaped charges were released below the solar terminator (to prevent photoionization) at altitudes near 400 km. The ambient ionospheric electron density was 5x10 5 cm -3 . The neutral barium jet was directed upwards and at an angle of nominally 45 degrees to B which gives approximately 3x10 23 neutrals with super critical velocity. Ions created by a CIV process in the region of the neutral jet would travel up along B into sunlight where they can be detected optically. Well defined ion clouds (max. brightness 750 R) were observed in both releases. An ionization rate of 0.8%s -1 (125s ionization time constant) can account for the observed ion cloud near the release field line, but the ionization rate falls off with increasing distance from the release. It is concluded that a CIV process was present in the neutral jet out to about 50 km from the release, which is significantly further than allowed by current theories

Současné tendence ve výzkumu péče: Zpráva z mezinárodní konference Critical Care

Czech Academy of Sciences Publication Activity Database

Uhde, Zuzana

2012-01-01

Roč. 13, č. 2 (2012), s. 113-115 ISSN 1213-0028. [Critical Care: Advancing an Ethics of Care in Theory and Practice. Brighton, 13.09.2012-14.09.2012] R&D Projects: GA ČR GAP404/10/0021 Institutional support: RVO:68378025 Keywords : care * gender * conference Subject RIV: AO - Sociology, Demography

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

Applicable regulations and development of surveillance experiments of criticality approach in the TRIGA III Mark reactor

International Nuclear Information System (INIS)

Gonzalez M, J.L.; Aguilar H, F.; Rivero G, T.; Sainz M, E.

2000-01-01

In the procedure elaborated to repair the vessel of TRIGA III Mark reactor is required to move toward two tanks of temporal storage the fuel elements which are in operation and the spent fuel elements which are in decay inside the reactor pool. The National Commission of Nuclear Safety and Safeguards (CNSNS) has requested as protection measure that it is carried out a surveillance of the criticality approach of the temporal storages. This work determines the main regulation aspects that entails an experiment of criticality approach, moreover, informing about the results obtained in the developing of this experiments. The regulation aspects are not exclusives for this work in the TRIGA Mark III reactor but they also apply toward any assembling of fissile material. (Author)

Evaluation of the concrete shield compositions from the 2010 criticality accident alarm system benchmark experiments at the CEA Valduc SILENE facility

International Nuclear Information System (INIS)

Miller, Thomas Martin; Celik, Cihangir; Dunn, Michael E; Wagner, John C; McMahan, Kimberly L; Authier, Nicolas; Jacquet, Xavier; Rousseau, Guillaume; Wolff, Herve; Savanier, Laurence; Baclet, Nathalie; Lee, Yi-kang; Trama, Jean-Christophe; Masse, Veronique; Gagnier, Emmanuel; Naury, Sylvie; Blanc-Tranchant, Patrick; Hunter, Richard; Kim, Soon; Dulik, George Michael; Reynolds, Kevin H.

2015-01-01

In October 2010, a series of benchmark experiments were conducted at the French Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA) Valduc SILENE facility. These experiments were a joint effort between the United States Department of Energy Nuclear Criticality Safety Program and the CEA. The purpose of these experiments was to create three benchmarks for the verification and validation of radiation transport codes and evaluated nuclear data used in the analysis of criticality accident alarm systems. This series of experiments consisted of three single-pulsed experiments with the SILENE reactor. For the first experiment, the reactor was bare (unshielded), whereas in the second and third experiments, it was shielded by lead and polyethylene, respectively. The polyethylene shield of the third experiment had a cadmium liner on its internal and external surfaces, which vertically was located near the fuel region of SILENE. During each experiment, several neutron activation foils and thermoluminescent dosimeters (TLDs) were placed around the reactor. Nearly half of the foils and TLDs had additional high-density magnetite concrete, high-density barite concrete, standard concrete, and/or BoroBond shields. CEA Saclay provided all the concrete, and the US Y-12 National Security Complex provided the BoroBond. Measurement data from the experiments were published at the 2011 International Conference on Nuclear Criticality (ICNC 2011) and the 2013 Nuclear Criticality Safety Division (NCSD 2013) topical meeting. Preliminary computational results for the first experiment were presented in the ICNC 2011 paper, which showed poor agreement between the computational results and the measured values of the foils shielded by concrete. Recently the hydrogen content, boron content, and density of these concrete shields were further investigated within the constraints of the previously available data. New computational results for the first experiment are now available

Critical care nurses' experiences of nursing mothers in an ICU after complicated childbirth.

Science.gov (United States)

Engström, Asa; Lindberg, Inger

2013-09-01

Providing nursing care for a critically ill obstetric patient or a patient who has just become a mother after a complicated birth can be a challenging experience for critical care nurses (CCNs). These patients have special needs because of the significant alterations in their physiology and anatomy together with the need to consider such specifics as breastfeeding and mother-child bonding. The aim with this study was to describe CCNs' experience of nursing the new mother and her family after a complicated childbirth. The design of the study was qualitative. Data collection was carried out through focus group discussions with 13 CCNs in three focus groups during spring 2012. The data were subjected to qualitative content analysis. The analysis resulted in the formulation of four categories: the mother and her vital functions are prioritized; not being responsible for the child and the father; an environment unsuited to the new family and collaboration with staff in neonatal and maternity delivery wards. When nursing a mother after a complicated birth the CCNs give her and her vital signs high priority. The fathers of the children or partners of the mothers are expected to take on the responsibility of caring for the newborn child and of being the link with the neonatal ward. It is suggested that education about the needs of new families for nursing care would improve the situation and have clinical implications. Whether the intensive care unit is always the best place in which to provide care for mothers and new families is debatable. © 2013 British Association of Critical Care Nurses.

Generation of integral experiment covariance data and their impact on criticality safety validation

Energy Technology Data Exchange (ETDEWEB)

Stuke, Maik; Peters, Elisabeth; Sommer, Fabian

2016-11-15

The quantification of statistical dependencies in data of critical experiments and how to account for them properly in validation procedures has been discussed in the literature by various groups. However, these subjects are still an active topic in the Expert Group on Uncertainty Analysis for Criticality Safety Assessment (UACSA) of the OECDNEA Nuclear Science Committee. The latter compiles and publishes the freely available experimental data collection, the International Handbook of Evaluated Criticality Safety Benchmark Experiments, ICSBEP. Most of the experiments were performed as series and share parts of experimental setups, consequently leading to correlation effects in the results. The correct consideration of correlated data seems to be inevitable if the experimental data in a validation procedure is limited or one cannot rely on a sufficient number of uncorrelated data sets, e.g. from different laboratories using different setups. The general determination of correlations and the underlying covariance data as well as the consideration of them in a validation procedure is the focus of the following work. We discuss and demonstrate possible effects on calculated k{sub eff}'s, their uncertainties, and the corresponding covariance matrices due to interpretation of evaluated experimental data and its translation into calculation models. The work shows effects of various modeling approaches, varying distribution functions of parameters and compares and discusses results from the applied Monte-Carlo sampling method with available data on correlations. Our findings indicate that for the reliable determination of integral experimental covariance matrices or the correlation coefficients a detailed study of the underlying experimental data, the modeling approach and assumptions made, and the resulting sensitivity analysis seems to be inevitable. Further, a Bayesian method is discussed to include integral experimental covariance data when estimating an

Generation of integral experiment covariance data and their impact on criticality safety validation

International Nuclear Information System (INIS)

Stuke, Maik; Peters, Elisabeth; Sommer, Fabian

2016-11-01

The quantification of statistical dependencies in data of critical experiments and how to account for them properly in validation procedures has been discussed in the literature by various groups. However, these subjects are still an active topic in the Expert Group on Uncertainty Analysis for Criticality Safety Assessment (UACSA) of the OECDNEA Nuclear Science Committee. The latter compiles and publishes the freely available experimental data collection, the International Handbook of Evaluated Criticality Safety Benchmark Experiments, ICSBEP. Most of the experiments were performed as series and share parts of experimental setups, consequently leading to correlation effects in the results. The correct consideration of correlated data seems to be inevitable if the experimental data in a validation procedure is limited or one cannot rely on a sufficient number of uncorrelated data sets, e.g. from different laboratories using different setups. The general determination of correlations and the underlying covariance data as well as the consideration of them in a validation procedure is the focus of the following work. We discuss and demonstrate possible effects on calculated k eff 's, their uncertainties, and the corresponding covariance matrices due to interpretation of evaluated experimental data and its translation into calculation models. The work shows effects of various modeling approaches, varying distribution functions of parameters and compares and discusses results from the applied Monte-Carlo sampling method with available data on correlations. Our findings indicate that for the reliable determination of integral experimental covariance matrices or the correlation coefficients a detailed study of the underlying experimental data, the modeling approach and assumptions made, and the resulting sensitivity analysis seems to be inevitable. Further, a Bayesian method is discussed to include integral experimental covariance data when estimating an application

Nursing care in a high-technological environment: Experiences of critical care nurses.

Science.gov (United States)

Tunlind, Adam; Granström, John; Engström, Åsa

2015-04-01

Management of technical equipment, such as ventilators, infusion pumps, monitors and dialysis, makes health care in an intensive care setting more complex. Technology can be defined as items, machinery and equipment that are connected to knowledge and management to maximise efficiency. Technology is not only the equipment itself, but also the knowledge of how to use it and the ability to convert it into nursing care. The aim of this study is to describe critical care nurses' experience of performing nursing care in a high technology healthcare environment. Qualitative, personal interviews were conducted during 2012 with eight critical care nurses in the northern part of Sweden. Interview transcripts were analysed using qualitative content analysis. Three themes with six categories emerged. The technology was described as a security that could facilitate nursing care, but also one that could sometimes present obstacles. The importance of using the clinical gaze was highlighted. Nursing care in a high technological environment must be seen as multi-faceted when it comes to how it affects CCNs' experience. The advanced care conducted in an ICU could not function without high-tech equipment, nor could care operate without skilled interpersonal interaction and maintenance of basal nursing. That technology is seen as a major tool and simultaneously as a barrier to patient-centred care. Copyright © 2014 Elsevier Ltd. All rights reserved.

Catalog and history of the experiments of criticality Saclay (1958-1964) Valduc / Building 10 (1964-2003); Catalogue et historique des experiences de criticite Saclay (1958 - 1964) Valduc / Batiment 10 (1964-2003)

Energy Technology Data Exchange (ETDEWEB)

Poullot, G.; Dumont, V.; Anno, J.; Cousinou, P. [Institut de Radioprotection et de Surete Nucleaire (IRSN), 92 - Fontenay aux Roses (France); Grivot, P.; Girault, E.; Fouillaud, P.; Barbry, F. [CEA Valduc, 21 - Is-sur-Tille (France)

2003-07-01

The group ' International Criticality Safety Evaluation Benchmark evaluation project ' (I.C.S.B.E.P.) has for aim to supply to the international community experiments of benchmarks criticality, of certified quality, used to guarantee the qualification of criticality calculation codes. Have been defined: a structure of experiments classification, a format of standard presentation, a structure of work with evaluation, internal and external checks, presentation in plenary session. After favourable opinion of the work group, the synthesis document called evaluation is integrated to the general report I.C.S.B.E.P. (N.C.)

Status of criticality safety research at NUCEF

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Ken [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Two critical facilities, named STACY (Static Experiment Critical Facility) and TRACY (Transient Experiment Critical Facility), at the Nuclear Fuel Cycle Safety Engineering Research Facility (NUCEF) started their hot operations in 1995. Since then, basic experimental data for criticality safety research have been accumulated using STACY, and supercritical experiments for the study of criticality accident in a reprocessing plant have been performed using TRACY. In this paper, the outline of those critical facilities and the main results of TRACY experiments are presented. (author)

Critical and Exponential Experiments on 19-Rod Clusters (R3 Fuel) in Heavy Water

Energy Technology Data Exchange (ETDEWEB)

Persson, R; Wikdahl, C E; Zadworski, Z

1962-03-15

Buckling measurements on clusters of 19 UO{sub 2} rods in heavy water have been performed in an exponential assembly and by means of substitution measurements in a critical facility. The material buckling was determined as a function of lattice pitch (range of V{sub mod} /V{sub fuel}: 7-22), internal spacing, void, and temperature (20 < T < 90 deg C). The change of diffusion coefficients (about 6-8 per cent) caused by voids was studied with single test fuel assemblies. The progressive substitution measurements have been analysed by means of a modified one-group perturbation theory in combination with an unconventional cell definition. The buckling differences between test and reference lattices are of the order of -1.0 to -3.5/m{sup 2}, The results of the exponential and the critical experiments are compared with similar measurements on the same kind of fuel at the Savannah River Laboratory. This comparison shows that the results of the various experiments agree quite well, whereas theoretical predictions fail in the extreme ranges.

Nurturing a lexical legacy: reading experience is critical for the development of word reading skill

Science.gov (United States)

Nation, Kate

2017-12-01

The scientific study of reading has taught us much about the beginnings of reading in childhood, with clear evidence that the gateway to reading opens when children are able to decode, or `sound out' written words. Similarly, there is a large evidence base charting the cognitive processes that characterise skilled word recognition in adults. Less understood is how children develop word reading expertise. Once basic reading skills are in place, what factors are critical for children to move from novice to expert? This paper outlines the role of reading experience in this transition. Encountering individual words in text provides opportunities for children to refine their knowledge about how spelling represents spoken language. Alongside this, however, reading experience provides much more than repeated exposure to individual words in isolation. According to the lexical legacy perspective, outlined in this paper, experiencing words in diverse and meaningful language environments is critical for the development of word reading skill. At its heart is the idea that reading provides exposure to words in many different contexts, episodes and experiences which, over time, sum to a rich and nuanced database about their lexical history within an individual's experience. These rich and diverse encounters bring about local variation at the word level: a lexical legacy that is measurable during word reading behaviour, even in skilled adults.

On the Evaluation of Pebble Bead Reactor Critical Experiments Using the Pebbed Code

International Nuclear Information System (INIS)

Gougar, Hans D.; Sen, R. Sonat

2014-01-01

Critical experiments pose a particular but necessary challenge to validating pebble bed reactor design codes. Fuel and core heterogeneities, impurities in graphite, variable packing of pebbles, and moderately strong neutronic coupling are among the factors that inject uncertainty into the results obtained with lower fidelity core physics models. Some of these are addressed in this study. The PEBBED pebble bed reactor fuel management code under development at the Idaho National Laboratory is designed for rapid design and analysis of pebble bed high temperature reactors (PBRs). Embedded within the code are the THERMIX-KONVEK thermal fluid solver and the COMBINE-7 spectrum generation code for inline cross section homogenization. Because 1D symmetry can be found at each stage of core heterogeneity; spherical at TRISO and pebble levels, and cylindrical at the control rod and core levels, the 1-D transport capability of ANISN is assumed to be sufficient in most cases for generating flux solutions for cross section homogenization. Furthermore, it is fast enough to be executed during the analysis or the equilibrium core. Multi-group diffusion-based design codes such as PEBBED and VSOP are not expected to yield the accuracy and resolution of continuous energy Monte Carlo codes for evaluation of critical experiments. Nonetheless, if the preparation of multigroup cross sections can adequately capture the physics of the mixing of PBR fuel elements and leakage from the core, reasonable results may be obtained. In this paper, results of the application of PEBBED to two critical experiments (HTR Proteus and HTR-10) and associated computational models are presented. The embedded 1-D transport solver is shown to capture the double heterogeneity of the pebble fuel in unit cell calculations. Eigenvalue calculations of a whole core are more challenging, particularly if the boron concentration is uncertain. The sensitivity of major safety parameters to variations in modeling

Analysis of experience-regulated transcriptome and imprintome during critical periods of mouse visual system development reveals spatiotemporal dynamics.

Science.gov (United States)

Hsu, Chi-Lin; Chou, Chih-Hsuan; Huang, Shih-Chuan; Lin, Chia-Yi; Lin, Meng-Ying; Tung, Chun-Che; Lin, Chun-Yen; Lai, Ivan Pochou; Zou, Yan-Fang; Youngson, Neil A; Lin, Shau-Ping; Yang, Chang-Hao; Chen, Shih-Kuo; Gau, Susan Shur-Fen; Huang, Hsien-Sung

2018-03-15

Visual system development is light-experience dependent, which strongly implicates epigenetic mechanisms in light-regulated maturation. Among many epigenetic processes, genomic imprinting is an epigenetic mechanism through which monoallelic gene expression occurs in a parent-of-origin-specific manner. It is unknown if genomic imprinting contributes to visual system development. We profiled the transcriptome and imprintome during critical periods of mouse visual system development under normal- and dark-rearing conditions using B6/CAST F1 hybrid mice. We identified experience-regulated, isoform-specific and brain-region-specific imprinted genes. We also found imprinted microRNAs were predominantly clustered into the Dlk1-Dio3 imprinted locus with light experience affecting some imprinted miRNA expression. Our findings provide the first comprehensive analysis of light-experience regulation of the transcriptome and imprintome during critical periods of visual system development. Our results may contribute to therapeutic strategies for visual impairments and circadian rhythm disorders resulting from a dysfunctional imprintome.

Space, energy and anisotropy effects on 238U effective capture cross sections in the resonance region

International Nuclear Information System (INIS)

Meftah, B.; Karam, R.A.

1984-01-01

Agreement between calculations and measurements within prescribed limits of error is always the test of engineering design analysis. Large and puzzling discrepancies do exist between several measured and calculated important integral reactor parameters. A thorough and exhaustive investigation of the methods used in reactor analysis revealed that in the generation of effective resonance cross sections no anisotropy effects are considered in the resonances. This is true in the integral transport and fundamental-mode codes. The neglect of anisotropy introduces errors at two levels: (1) the effective group cross sections such as σsub(c), σsub(f) and σsub(s); and (2) the diffusion coefficients and P 1 and higher components of the scattering cross sections. The study showed that the inclusion of linear scattering anisotropy increases, in general, the cell effective capture cross section of 238 U in both ZPR-6/5 and TRX-3 reactors. The increase was up to 2% in TRX-3 and 0.5% in ZPR-6/5. The effect on the multiplication factor was -0.003% Δk/k for ZPR-6/5 and -0.05% Δk/k for TRX-3. (author)

Critical experiments analyses by using 70 energy group library based on ENDF/B-VI

Energy Technology Data Exchange (ETDEWEB)

Tahara, Yoshihisa; Matsumoto, Hideki [Mitsubishi Heavy Industries Ltd., Yokohama (Japan). Nuclear Energy Systems Engineering Center; Huria, H.C.; Ouisloumen, M.

1998-03-01

The newly developed 70-group library has been validated by comparing kinf from a continuous energy Monte-Carlo code MCNP and two dimensional spectrum calculation code PHOENIX-CP. The code employs Discrete Angular Flux Method based on Collision Probability. The library has been also validated against a large number of critical experiments and numerical benchmarks for assemblies with MOX and Gd fuels. (author)

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)

Reactor physics experiments in PURNIMA sub critical facility coupled with 14 MeV neutron source

International Nuclear Information System (INIS)

Kumar, Rajeev; Degweker, S.B.; Patel, Tarun; Bishnoi, Saroj; Adhikari, P.S.

2011-01-01

Accelerator Driven Sub-critical Systems (ADSS) are attracting increasing worldwide attention due to their superior safety characteristics and their potential for burning actinide and fission product waste and energy production. A number of countries around the world have drawn up roadmaps/programs for development of ADSS. Indian interest in ADSS has an additional dimension, which is related to the planned utilization of our large thorium reserves for future nuclear energy generation. A programme for development of ADSS is taken up at the Bhabha Atomic Research Centre (BARC) in India. This includes R and D activities for high current proton accelerator development, target development and Reactor Physics studies. As part of the ADSS Reactor Physics research programme, a sub-critical facility is coming up in BARC which will be coupled with an existing D-D/D-T neutron generator. Two types of cores are planned. In one of these, the sub-critical reactor assembly consists of natural uranium moderated by high density polyethylene (HDP) and reflected by BeO. The other consists of natural uranium moderated by light water. The maximum neutron yield of the neutron source with tritium target is around 10 10 neutron per sec. Various reactor physics experiments like measurement of the source strength, neutron flux distribution, buckling estimation and sub-critical source multiplication are planned. Apart from this, measurement of the total fission power and neutron spectrum will also be carried out. Mainly activation detectors will be used in all in-core neutron flux measurement. Measurement of the degree of sub-criticality by various deterministic and noise methods is planned. Helium detectors with advanced data acquisition card will be used for the neutron noise experiments. Noise characteristics of ADSS are expected to be different from that of traditional reactors due to the non-Poisson statistical features of the source. A new theory incorporating these features has been

Contributions to the qualification of the ''CRISTAL'' criticality calculi scheme: interpretation of critical experiments. Elaboration of a characterization system of neutronic configurations

International Nuclear Information System (INIS)

Gagnier, E.

1999-06-01

This thesis work is about the validation of the new criticality-safety package CRISTAL and contributes to the modernization and the improvement of the computational tools. The first part presents neutronic elements, the objectives of safety criticality studies and the package CRISTAL. Then, the validation work concerned two series of experiments involving uranyl solutions (UO 2 F 2 ) and UO 2 powders. For these experiments, the differences between the computation results and the experimental results were analysed. It was highlighted interesting physical phenomena such of the compensations of errors between the approximate representation by the 99 energy group structure on the first resonance of oxygen and the anisotropy of the diffusion simulation as well as the influence of uranium 234 in high enriched solutions in uranium 235. Once the work of the experimental qualification carried out, raises the question of the use the base of qualification and the ''calculation-experiment'' variations which are referred to it. It is often difficult to establish the link between the ''studied configuration'' and the experiments of the base of qualification. The presented characterisation system proposes to answer in a way automatic and quantified this difficulty: - in bringing an answer on the package qualification for the studied configuration, - in giving an estimate of the package bias. To answer these points, it was defined a set of 35 characteristic neutronic parameters representing the behaviour of the medium. To process the information brought by these parameters and to use it to answer the objectives of the system, we called upon statistical methods (Principal Components Analysis and Sliced Inverse Regression). The results obtained in the feasibility studies showed the relevance of these methods for the considered objectives. (author)

A framework guiding critical thinking through reflective journal documentation: a Middle Eastern experience.

Science.gov (United States)

Simpson, Elaine; Courtney, Mary

2007-08-01

The purpose of this paper is to present a framework to guide critical thinking through reflective journaling, and describe how a group of 20 Middle Eastern nurses used reflective journaling to enhance their practice. Journal documentation was used during clinical practicum to foster the development of critical thinking in order to assist nurses when analysing and evaluating their clinical experiences. The findings from this study demonstrated that nurses accepted the framework for journal documentation because it provided structure for reflection, speculation, synthesis and metacognition of events experienced during clinical practice. Journaling gave nurses the opportunity to transfer thoughts onto paper and write down subjective and objective data, and created dialogue between the nurse educators and nurses. They were engaged in productive and positive activity to enhance their nursing practice. Nurses also commented that writing helped to develop their confidence in writing English.

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

Manipulation of BDNF signaling modifies the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex.

Science.gov (United States)

Anomal, Renata; de Villers-Sidani, Etienne; Merzenich, Michael M; Panizzutti, Rogerio

2013-01-01

Sensory experience powerfully shapes cortical sensory representations during an early developmental "critical period" of plasticity. In the rat primary auditory cortex (A1), the experience-dependent plasticity is exemplified by significant, long-lasting distortions in frequency representation after mere exposure to repetitive frequencies during the second week of life. In the visual system, the normal unfolding of critical period plasticity is strongly dependent on the elaboration of brain-derived neurotrophic factor (BDNF), which promotes the establishment of inhibition. Here, we tested the hypothesis that BDNF signaling plays a role in the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex. Elvax resin implants filled with either a blocking antibody against BDNF or the BDNF protein were placed on the A1 of rat pups throughout the critical period window. These pups were then exposed to 7 kHz pure tone for 7 consecutive days and their frequency representations were mapped. BDNF blockade completely prevented the shaping of cortical tuning by experience and resulted in poor overall frequency tuning in A1. By contrast, BDNF infusion on the developing A1 amplified the effect of 7 kHz tone exposure compared to control. These results indicate that BDNF signaling participates in the experience-dependent plasticity induced by pure tone exposure during the critical period in A1.

Manipulation of BDNF signaling modifies the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex.

Directory of Open Access Journals (Sweden)

Renata Anomal

Full Text Available Sensory experience powerfully shapes cortical sensory representations during an early developmental "critical period" of plasticity. In the rat primary auditory cortex (A1, the experience-dependent plasticity is exemplified by significant, long-lasting distortions in frequency representation after mere exposure to repetitive frequencies during the second week of life. In the visual system, the normal unfolding of critical period plasticity is strongly dependent on the elaboration of brain-derived neurotrophic factor (BDNF, which promotes the establishment of inhibition. Here, we tested the hypothesis that BDNF signaling plays a role in the experience-dependent plasticity induced by pure tone exposure during the critical period in the primary auditory cortex. Elvax resin implants filled with either a blocking antibody against BDNF or the BDNF protein were placed on the A1 of rat pups throughout the critical period window. These pups were then exposed to 7 kHz pure tone for 7 consecutive days and their frequency representations were mapped. BDNF blockade completely prevented the shaping of cortical tuning by experience and resulted in poor overall frequency tuning in A1. By contrast, BDNF infusion on the developing A1 amplified the effect of 7 kHz tone exposure compared to control. These results indicate that BDNF signaling participates in the experience-dependent plasticity induced by pure tone exposure during the critical period in A1.

Evaluation of effects on integral parameters, due to homogenization of one region of a core-blanket system

International Nuclear Information System (INIS)

Assis, J.T. de

1982-01-01

The effects produced on the integral parameters due to the homogenization in the core-blanket inrterface, were evaluated, adopting an 1D diffusion calculation. The calculation for one plane cell with the characteristics of the critical mounting ZPR-6-5, was done using the Hetaire computer code with the Carnaval II data library for 25 energy groups. For the transport calculation the ANISN and RMAT1D computer codes were used. By the homogenization of an interface region, flux values, cross sections and reactivity are obtained for several thicknesses of this region. The results of diffusion calculation are compared with the transport calculation. (E.G.) [pt

How do general practice registrars learn from their clinical experience? A critical incident study.

Science.gov (United States)

Holmwood, C

1997-01-01

This preliminary study of RACGP registrars in the period of subsequent general practice experience examines the types of clinical experiences from which registrars learn, what they learn from the experiences and the process of learning from such experiences. A critical incident method was used on a semi structured interview process. Registrars were asked to recall clinical incidents where they had learnt something of importance. Data were sorted and categorised manually. Nine registrars were interviewed before new categories of data ceased to develop. Registrars learnt from the opportunity to follow up patients. An emotional response to the interaction was an important part of the learning process. Learning from such experiences is haphazard and unstructured. Registrars accessed human resources in response to their clinical difficulties rather than text or electronic based information sources. Registrars should be aware of their emotional responses to interactions with patients; these emotional responses often indicate important learning opportunities. Clinical interactions and resultant learning could be made less haphazard by structuring consultations with patients with specific problems. These learning opportunities should be augmented by the promotion of follow up of patients.

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.

1997-10-01

The Solution High-Energy Burst Assembly (SHEBA) was originally constructed during 1980 and was designed to be a clean free-field geometry, right-circular, cylindrically symmetric critical assembly employing U(5%)O 2 F 2 solution as fuel. A second version of SHEBA, employing the same fuel but equipped with a fuel pump and shielding pit, was commissioned in 1993. This report includes data and operating experience for the 1993 SHEBA only. Solution-fueled benchmark work focused on the development of experimental measurements of the characterization of SHEBA; a summary of the results are given. A description of the system and the experimental results are given in some detail in the report. Experiments were designed to: (1) study the behavior of nuclear excursions in a low-enrichment solution, (2) evaluate accidental criticality alarm detectors for fuel-processing facilities, (3) provide radiation spectra and dose measurements to benchmark radiation transport calculations on a low-enrichment solution system similar to centrifuge enrichment plants, and (4) provide radiation fields to calibrate personnel dosimetry. 15 refs., 37 figs., 10 tabs

Space, the final frontier: A critical review of recent experiments performed in microgravity.

Science.gov (United States)

Vandenbrink, Joshua P; Kiss, John Z

2016-02-01

Space biology provides an opportunity to study plant physiology and development in a unique microgravity environment. Recent space studies with plants have provided interesting insights into plant biology, including discovering that plants can grow seed-to-seed in microgravity, as well as identifying novel responses to light. However, spaceflight experiments are not without their challenges, including limited space, limited access, and stressors such as lack of convection and cosmic radiation. Therefore, it is important to design experiments in a way to maximize the scientific return from research conducted on orbiting platforms such as the International Space Station. Here, we provide a critical review of recent spaceflight experiments and suggest ways in which future experiments can be designed to improve the value and applicability of the results generated. These potential improvements include: utilizing in-flight controls to delineate microgravity versus other spaceflight effects, increasing scientific return via next-generation sequencing technologies, and utilizing multiple genotypes to ensure results are not unique to one genetic background. Space experiments have given us new insights into plant biology. However, to move forward, special care should be given to maximize science return in understanding both microgravity itself as well as the combinatorial effects of living in space. Copyright © 2015. Published by Elsevier Ireland Ltd.

The Brazilian Experience with Agroecological Extension: A Critical Analysis of Reform in a Pluralistic Extension System

Science.gov (United States)

Diesel, Vivien; Miná Dias, Marcelo

2016-01-01

Purpose: To analyze the Brazilian experience in designing and implementing a recent extension policy reform based on agroecology, and reflect on its wider theoretical implications for extension reform literature. Design/methodology/approach: Using a critical public analysis we characterize the evolution of Brazilian federal extension policy…

Opening the Door: The Experience of Chronic Critical Illness in a Long-Term Acute Care Hospital.

Science.gov (United States)

Lamas, Daniela J; Owens, Robert L; Nace, R Nicholas; Massaro, Anthony F; Pertsch, Nathan J; Gass, Jonathon; Bernacki, Rachelle E; Block, Susan D

2017-04-01

Chronically critically ill patients have recurrent infections, organ dysfunction, and at least half die within 1 year. They are frequently cared for in long-term acute care hospitals, yet little is known about their experience in this setting. Our objective was to explore the understanding and expectations and goals of these patients and surrogates. We conducted semi-structured interviews with chronically critically ill long-term acute care hospital patients or surrogates. Conversations were recorded, transcribed, and analyzed. One long-term acute care hospital. Chronically critically ill patients, defined by tracheotomy for prolonged mechanical ventilation, or surrogates. Semi-structured conversation about quality of life, expectations, and planning for setbacks. A total of 50 subjects (30 patients and 20 surrogates) were enrolled. Thematic analyses demonstrated: 1) poor quality of life for patients; 2) surrogate stress and anxiety; 3) optimistic health expectations; 4) poor planning for medical setbacks; and 5) disruptive care transitions. Nearly 80% of patient and their surrogate decision makers identified going home as a goal; 38% were at home at 1 year. Our study describes the experience of chronically critically ill patients and surrogates in an long-term acute care hospital and the feasibility of patient-focused research in this setting. Our findings indicate overly optimistic expectations about return home and unmet palliative care needs, suggesting the need for integration of palliative care within the long-term acute care hospital. Further research is also needed to more fully understand the challenges of this growing population of ICU survivors.

Thinking Critically about Critical Thinking: Integrating Online Tools to Promote Critical Thinking

Directory of Open Access Journals (Sweden)

B. Jean Mandernach

2006-01-01

Full Text Available The value and importance of critical thinking is clearly established; the challenge for instructors lies in successfully promoting students’ critical thinking skills within the confines of a traditional classroom experience. Since instructors are faced with limited student contact time to meet their instructional objectives and facilitate learning, they are often forced to make instructional decisions between content coverage, depth of understanding, and critical analysis of course material. To address this dilemma, it is essential to integrate instructional strategies and techniques that can efficiently and effectively maximize student learning and critical thinking. Modern advances in educational technology have produced a range of online tools to assist instructors in meeting this instructional goal. This review will examine the theoretical foundations of critical thinking in higher education, discuss empirically-based strategies for integrating online instructional supplements to enhance critical thinking, offer techniques for expanding instructional opportunities outside the limitations of traditional class time, and provide practical suggestions for the innovative use of critical thinking strategies via online resources.

Critical experiments on single-unit spherical plutonium geometries reflected and moderated by oil

International Nuclear Information System (INIS)

Rothe, R.E.

1997-05-01

Experimental critical configurations are reported for several dozen spherical and hemispherical single-unit assemblies of plutonium metal. Most were solid but many were hollow-centered, thick, shell-like geometries. All were constructed of nested plutonium (mostly 2139 Pu) metal hemispherical shells. Three kinds of critical configurations are reported. Two required interpolation and/or extrapolation of data to obtain the critical mass because reflector conditions were essentially infinite. The first finds the plutonium essentially fully reflected by a hydrogen-rich oil; the second is essentially unreflected. The third kind reports the critical oil reflector height above a large plutonium metal assembly of accurately known mass (no interpolation required) when that mass was too great to permit full oil reflection. Some configurations had thicknesses of mild steel just outside the plutonium metal, separating it from the oil. These experiments were performed at the Rocky Flats Critical Mass Laboratory in the late 1960s. They have not been published in a form suitable for benchmark-quality comparisons against state-of-the-art computational techniques until this paper. The age of the data and other factors lead to some difficulty in reconstructing aspects of the program and may, in turn, decrease confidence in certain details. Whenever this is true, the point is acknowledged. The plutonium metal was alpha-phase 239 Pu containing 5.9 wt-% 240 Pu. All assemblies were formed by nesting 1.667-mm-thick (nominal) bare plutonium metal hemispherical shells, also called hemishells, until the desired configuration was achieved. Very small tolerance gaps machined into radial dimensions reduced the effective density a small amount in all cases. Steel components were also nested hemispherical shells; but these were nominally 3.333-mm thick. Oil was used as the reflector because of its chemical compatibility with plutonium metal

Critical experiments on minimal-content gadolinia for above-5wt% enrichment fuels in Toshiba NCA

International Nuclear Information System (INIS)

Kikuchi, Tsukasa; Watanabe, Shouichi; Yoshioka, Kenichi; Mitsuhashi, Ishi; Kumanomido, Hironori; Sugahara, Satoshi; Hiraiwa, Kouji

2009-01-01

A concept of 'minimal-content gadolinia' with a content of less than several hundred ppm mixed in the 'above-5wt% enrichment UO 2 fuel' for super high burnup is proposed for ensuring the criticality safety in the UO 2 fuel fabrication facility for light water reactors (LWRs) without increase in investment cost. Required gadolinia contents calculated were from 53 to 305 ppm for enrichments of UO 2 powders for boiling water reactor (BWR) fuel from 6 to 10 wt%. It is expected that the minimal-content gadolinia yields an acceptable reactivity suppression at the beginning of operating cycle and no reactivity penalty at the end of operating cycle due to no residual gadolinium. A series of critical experiments were carried out in the Toshiba Nuclear Critical Assembly (NCA). Reactivity effects of the gadolinia were measured to clarify the nuclear characteristics, and the measured values and the calculated values agreed within 5%. (author)

Integrating Critical Pedagogy theory and practice: classroom experiences in Argentinean EFL teacher education

Directory of Open Access Journals (Sweden)

Zelmira Álvarez

2012-10-01

Full Text Available Argentinean ESL teacher education presupposes an understanding of the past and present world role of English. Thus, the curriculum of the ESL Teacher Education Program at Universidad Nacional de Mar del Plata includes subjects dealing with historical, cultural, and social questions concerning English-cultures worldwide. This paper explains how some of these issues are addressed in activities carried out in the sophomore course Overall Communication. They involve critical and postcolonial analysis of the film Slumdog millionaire (2008 and the story “The free radio” (Rushdie, 1994. Activities aim at making student-teachers aware of their need to critically address concepts related to race, ethnicity, class, religion, education, and language to unveil the political, economic, and social issues underlying the teaching and learning of English. The choice of materials and authors also aims at listening to English-speaking voices other than those stemming from (former imperial centers. Activities involve research and discussions of problematics such as oppression, exclusion, and illiteracy. This paper will analyze sample written productions by students working collaboratively among themselves and cooperatively with their teachers. In short, this is an experience that strives at showing how Critical Pedagogy can become a site for raising questions concerning power and EFL teaching and learning.

Application of the “best representativity” method to a PWR fuel calculation using the critical experiments at the Toshiba NCA facility

International Nuclear Information System (INIS)

Umano, Takuya; Yoshioka, Kenichi; Obara, Toru

2015-01-01

Highlights: • Calculation procedures are easier than those of the cross-section adjustment method. • In addition, few cases of experimental results, two or three cases for example, can be well managed with the method. • Different from the bias factor method, a representativity factor is simultaneously obtained to know the whole quality of utilized experiments. • After easier process of calculations, it is possible to obtain a correction value of a particular physical property with the method. • Our proposed method was considered to be applicable to the correction of the infinite neutron multiplication factor in LWR studies. - Abstract: To judge the applicability of a critical experiment, it is necessary to confirm the similarities of the experiment with actual reactor conditions or equipment. The concept of the “representativity factor” has been well adopted since the late 1970’s, particularly for fast breeder reactors (FBRs) and future reactor studies. In our previous study, we extended this concept to the design of a light water reactor (LWR) system, and derived mathematical formulas for a new numerical evaluation method to correct a physical property of a target system. This method is different from the cross-section adjustment method and the bias factor method. For the first qualification of the method, sample calculations were carried out to correct the effective neutron multiplication factor through critical experiments at the Toshiba Nuclear Critical Assembly (NCA) facility. We also compared the result with that of the Product of Exponentiated experimental values method (PE method) of the extended bias factor methods. A good agreement was observed. The purpose of this study was to demonstrate the applicability of the method to the infinite neutron multiplication factor. Using the method and three kinds of critical experiments of NCA, calculations were performed to correct the infinite neutron multiplication factor of a pressurized water

Critical experiment and analysis for nitride fuel fast reactor using FCA

International Nuclear Information System (INIS)

Andoh, Masaki; Iijima, Susumu; Okajima, Shigeaki; Sakurai, Takeshi; Oigawa, Hiroyuki

2000-03-01

As a research on FBR with new types of fuel, a series of experiments on a nitride fuel fast reactor was carried out at Fast Critical Assembly (FCA) to evaluate the calculation accuracy on the neutronic characteristics of the reactor. In this study, criticality, sample reactivity worth and sodium void reactivity worth were measured in the FCA XIX-2 core simulating a nitride fuel fast reactor and were analyzed using the standard analysis method for FCA fast reactor cores. The accuracy of the analysis on the effective multiplication factor was the same as those of the other FCA cores. For the plate sample reactivity worth, the calculation on the radial distribution of plutonium plate reactivity worth overestimated the measurement depending on the distance from the center of the core. For the sodium void reactivity worth, the calculation overestimated the experimental value 10 to 20% at the core center, while the overestimation was improved as the voided position was located at the core boundary. It was found that the transport effect was considerable even at the center of the core. It was considered that the calculation accuracy on the non-leakage term of the void reactivity worth and transport correction should be improved. (author)

Plasma-wall interaction data needs critical to a Burning Core Experiment (BCX)

International Nuclear Information System (INIS)

1985-11-01

The Division of Development and Technology has sponsored a four day US-Japan workshop ''Plasma-Wall Interaction Data Needs Critical to a Burning Core Experiment (BCX)'', held at Sandia National Laboratories, Livermore, California on June 24 to 27, 1985. The workshop, which brought together fifty scientists and engineers from the United States, Japan, Germany, and Canada, considered the plasma-material interaction and high heat flux (PMI/HHF) issues for the next generation of magnetic fusion energy devices, the Burning Core Experiment (BCX). Materials options were ranked, and a strategy for future PMI/HHF research was formulated. The foundation for international collaboration and coordination of this research was also established. This volume contains the first two of the five technical sessions. The first one being the BCX overview, the second on the BCX candidate materials. The remaining three sessions in volume two are on the plasma materials interaction issues, research facilities and small working group meeting on graphite, beryllium, advanced materials and future collaborations

Plasma-wall interaction data needs critical to a Burning Core Experiment (BCX)

International Nuclear Information System (INIS)

1985-11-01

The Division of Development and Technology has sponsored a four day US-Japan workshop ''Plasma-Wall Interaction Data Needs Critical to a Burning Core Experiment (BCX)'', held at Sandia National Laboratories, Livermore, California on June 24 to 27, 1985. The workshop, which brought together fifty scientists and engineers from the United States, Japan, Germany, and Canada, considered the plasma-material interaction and high heat flux (PMI/HHF) issues for the next generation of magnetic fusion energy devices, the Burning Core Experiment (BCX). Materials options were ranked, and a strategy for future PMI/HHF research was formulated. The foundation for international collaboration and coordination of this research was also established. This volume contains the last three of the five technical sessions. The first of the three is on plasma materials interaction issues, the second is on research facilities and the third is from smaller working group meetings on graphite, beryllium, advanced materials and future collaborations

Plasma-wall interaction data needs critical to a Burning Core Experiment (BCX)

Energy Technology Data Exchange (ETDEWEB)

1985-11-01

The Division of Development and Technology has sponsored a four day US-Japan workshop ''Plasma-Wall Interaction Data Needs Critical to a Burning Core Experiment (BCX)'', held at Sandia National Laboratories, Livermore, California on June 24 to 27, 1985. The workshop, which brought together fifty scientists and engineers from the United States, Japan, Germany, and Canada, considered the plasma-material interaction and high heat flux (PMI/HHF) issues for the next generation of magnetic fusion energy devices, the Burning Core Experiment (BCX). Materials options were ranked, and a strategy for future PMI/HHF research was formulated. The foundation for international collaboration and coordination of this research was also established. This volume contains the last three of the five technical sessions. The first of the three is on plasma materials interaction issues, the second is on research facilities and the third is from smaller working group meetings on graphite, beryllium, advanced materials and future collaborations.

Criticality of a 237Np sphere

International Nuclear Information System (INIS)

Sanchez, Rene G.; Loaiza, David J.; Kimpland, Robert H.; Hayes, David K.; Cappiello, Charlene C.; Myers, William L.; Jaegers, Peter J.; Clement, Steven D.; Butterfield, Kenneth B.

2003-01-01

A critical mass experiment using a 6-kg 237 Np sphere has been performed. The purpose of the experiment is to get a better estimate of the critical mass of 237 Np. To attain criticality, the 237 Np sphere was surrounded with 93 wt% 235 U shells. A 1/M as a function of uranium mass was performed. An MCNP neutron transport code was used to model the experiment. The MCNP code yielded a k eff of 0.99089 ± 0.0003 compared with a k eff 1.0026 for the experiment. Based on these results, it is estimated that the critical mass of 237 Np ranges from kilogram weights in the high fifties to low sixties. (author)

Nuclear criticality predictability

International Nuclear Information System (INIS)

Briggs, J.B.

1999-01-01

As a result of lots of efforts, a large portion of the tedious and redundant research and processing of critical experiment data has been eliminated. The necessary step in criticality safety analyses of validating computer codes with benchmark critical data is greatly streamlined, and valuable criticality safety experimental data is preserved. Criticality safety personnel in 31 different countries are now using the 'International Handbook of Evaluated Criticality Safety Benchmark Experiments'. Much has been accomplished by the work of the ICSBEP. However, evaluation and documentation represents only one element of a successful Nuclear Criticality Safety Predictability Program and this element only exists as a separate entity, because this work was not completed in conjunction with the experimentation process. I believe; however, that the work of the ICSBEP has also served to unify the other elements of nuclear criticality predictability. All elements are interrelated, but for a time it seemed that communications between these elements was not adequate. The ICSBEP has highlighted gaps in data, has retrieved lost data, has helped to identify errors in cross section processing codes, and has helped bring the international criticality safety community together in a common cause as true friends and colleagues. It has been a privilege to associate with those who work so diligently to make the project a success. (J.P.N.)

Critical heat flux experiments in a circular tube with heavy water and light water. (AWBA Development Program)

International Nuclear Information System (INIS)

Williams, C.L.; Beus, S.G.

1980-05-01

Experiments were performed to establish the critical heat flux (CHF) characteristics of heavy water and light water. Testing was performed with the up-flow of heavy and of light water within a 0.3744 inch inside diameter circular tube with 72.3 inches of heated length. Comparisons were made between heavy water and light water critical heat flux levels for the same local equilibrium quality at CHF, operating pressure, and nominal mass velocity. Results showed that heavy water CHF values were, on the average, 8 percent below the light water CHF values

Impediments to User Gains: Experiences from a Critical Participatory Design Project

DEFF Research Database (Denmark)

Bossen, Claus; Dindler, Christian; Iversen, Ole Sejer

2012-01-01

interviews with participants in a project aimed at developing technology that fosters engaging museum experiences, and rethinking cultural heritage communication. Despite the use of established PD techniques by experienced PD practitioners, a significant number of frustrations relating to the PD process were...... prominent in the research study. Based on these findings, we provide an analysis of impediments for users gains in PD projects: Differences between aims were unresolved, absence of a shared set-up for collaboration and different conceptions of technology.......Actual studies of user gains from involvement in design processes are few, although a concern for users’ gains is a core characteristic of participatory design (PD). We explore the question of user gains through a retrospective evaluation of a critical PD project. We conducted ten qualitative...

Enabling software defined networking experiments in networked critical infrastructures

Directory of Open Access Journals (Sweden)

Béla Genge

2014-05-01

Full Text Available Nowadays, the fact that Networked Critical Infrastructures (NCI, e.g., power plants, water plants, oil and gas distribution infrastructures, and electricity grids, are targeted by significant cyber threats is well known. Nevertheless, recent research has shown that specific characteristics of NCI can be exploited in the enabling of more efficient mitigation techniques, while novel techniques from the field of IP networks can bring significant advantages. In this paper we explore the interconnection of NCI communication infrastructures with Software Defined Networking (SDN-enabled network topologies. SDN provides the means to create virtual networking services and to implement global networking decisions. It relies on OpenFlow to enable communication with remote devices and has been recently categorized as the “Next Big Technology”, which will revolutionize the way decisions are implemented in switches and routers. Therefore, the paper documents the first steps towards enabling an SDN-NCI and presents the impact of a Denial of Service experiment over traffic resulting from an XBee sensor network which is routed across an emulated SDN network.

Alecto - results obtained with homogeneous critical experiments on plutonium 239, uranium 235 and uranium 233; Alecto - resultats des experiences critiques homogenes realisees sur le plutonium 239, l'uranium 235 et l'uranium 233

Energy Technology Data Exchange (ETDEWEB)

Bruna, J G; Brunet, J P; Caizegues, R; Clouet d' Orval, Ch; Kremser, J; Tellier, H; Verriere, Ph [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

In this report are given the results of the homogeneous critical experiments ALECTO, made on plutonium 239, uranium 235 and uranium 233. After a brief description of the equipment, the critical masses for cylinders of diameters varying from 25 to 42 cm, are given and compared with other values (foreign results, criticality guide). With respect to the specific conditions of neutron reflection in the ALECTO experiments the minimal values of critical masses are: Pu239 M{sub c} = 910 {+-} 10 g, U235 M{sub c} = 1180 {+-} 12 g and U233 M{sub c} = 960 {+-} 10 g. Experiments relating to cross sections and constants to be used on these materials are presented. Lastly, kinetic experiments allow to compare pulsed neutron methods to fluctuation methods. [French] On presente dans ce rapport les resultats des experiences critiques homogenes ALECTO, effectuees sur le plutonium 239, l'uranium 235 et l'uranium 233. Apres avoir rappele la description des installations, on donne les masses critiques pour des cylindres de diametres variant entre 25 et 42 cm, qui sont comparees avec d'autres chiffres (resultats etrangers, guide de criticite). Dans les gammes des diametres etudies pour des cuves a fond plat reflechies lateralement, la valeur minimale des masses critiques est la suivante: Pu239 M{sub c} = 910 {+-} 10 g, U235 M{sub c} = 1180 {+-} 12 g et U233 M{sub c} 960 {+-} 10 g. Des experiences portant sur les sections efficaces et les constantes a utiliser sur ces milieux sont ensuite presentees. Enfin des experiences de cinetique permettent une comparaison entre la methode des neutrons pulses et la methode des fluctuations. (auteur)

Mothers and Fathers Experience Stress of Congenital Heart Disease Differently: Recommendations for Pediatric Critical Care.

Science.gov (United States)

Sood, Erica; Karpyn, Allison; Demianczyk, Abigail C; Ryan, Jennie; Delaplane, Emily A; Neely, Trent; Frazier, Aisha H; Kazak, Anne E

2018-03-10

To inform pediatric critical care practice by examining how mothers and fathers experience the stress of caring for a young child with congenital heart disease and use hospital and community supports. Qualitative study of mothers and fathers of young children with congenital heart disease. Tertiary care pediatric hospital in the Mid-Atlantic region of the United States. Thirty-four parents (20 mothers, 14 fathers) from diverse backgrounds whose child previously underwent cardiac surgery during infancy. Subjects participated in semi-structured, individual interviews about their experiences and psychosocial needs at the time of congenital heart disease diagnosis, surgical admission, and discharge to home after surgery. Qualitative interview data were coded, and consistent themes related to emotional states, stressors, and supports were identified. Fathers experience and respond to the stressors and demands of congenital heart disease in unique ways. Fathers often described stress from not being able to protect their child from congenital heart disease and the associated surgeries/pain and from difficulties balancing employment with support for their partner and care of their congenital heart disease child in the hospital. Fathers were more likely than mothers to discuss support from the work environment (coworkers/managers, flexible scheduling, helpful distraction) and were less likely to describe the use of hospital-based resources or congenital heart disease peer-to-peer supports. This study highlights the importance of understanding the paternal experience and tailoring interventions to the unique needs of both mothers and fathers. Opportunities for critical care practice change to promote the mental health of mothers and fathers following a diagnosis of congenital heart disease are discussed.

Critical experiments supporting underwater storage of tightly packed configurations of spent fuel rods

International Nuclear Information System (INIS)

Hoovler, G.S.; Baldwin, M.N.

1981-04-01

Criticla arrays of 2.5%-enriched UO 2 fuel rods that simulate underwater rod storage of spent power reactor fuel are being constructed. Rod storage is a term used to describe a spent fuel storage concept in which the fuel bundles are disassembled and the rods are packed into specially designed cannisters. Rod storage would substantially increase the amount of fuel that could be stored in available space. These experiments are providing criticality data against which to benchmark nuclear codes used to design tightly packed rod storage racks

Verification of HELIOS-MASTER system through benchmark of critical experiments

International Nuclear Information System (INIS)

Kim, H. Y.; Kim, K. Y.; Cho, B. O.; Lee, C. C.; Zee, S. O.

1999-01-01

The HELIOS-MASTER code system is verified through the benchmark of the critical experiments that were performed by RRC 'Kurchatov Institute' with water-moderated hexagonally pitched lattices of highly enriched Uranium fuel rods (80w/o). We also used the same input by using the MCNP code that was described in the evaluation report, and compared our results with those of the evaluation report. HELIOS, developed by Scandpower A/S, is a two-dimensional transport program for the generation of group cross-sections, and MASTER, developed by KAERI, is a three-dimensional nuclear design and analysis code based on the two-group diffusion theory. It solves neutronics model with the AFEN (Analytic Function Expansion Nodal) method for hexagonal geometry. The results show that the HELIOS-MASTER code system is fast and accurate enough to be used as nuclear core analysis tool for hexagonal geometry

Analysis and evaluation of ZPPR critical experiments for a 100 kilowatt-electric space reactor

International Nuclear Information System (INIS)

McFarlane, H.F.; Collins, P.J.; Carpenter, S.G.; Olsen, D.N.; Smith, D.M.; Schaefer, R.W.; Doncals, R.A.; Andre, S.V.; Porter, C.A.; Cowan, C.L.; Stewart, S.L.; Protsik, R.

1990-01-01

ZPPR critical experiments were used for physics testing the reactor design of the SP-100, a 100-kW thermoelectric LMR that is being developed to provide electrical power for space applications. These tests validated all key physics characteristics of the design, including the ultimate safety in the event of a launch or re-entry accident. Both the experiments and the analysis required the use of techniques not previously needed for fast reactor designs. A few significant discrepancies between the experimental and calculated results leave opportunities for further reductions in the mass of the SP-100. An initial investigation has been made into application of the ZPPR-20 results, along with those of other relevant integral data, to the SP-100 design

Critical periods after stroke study: translating animal stroke recovery experiments into a clinical trial

Science.gov (United States)

Dromerick, Alexander W.; Edwardson, Matthew A.; Edwards, Dorothy F.; Giannetti, Margot L.; Barth, Jessica; Brady, Kathaleen P.; Chan, Evan; Tan, Ming T.; Tamboli, Irfan; Chia, Ruth; Orquiza, Michael; Padilla, Robert M.; Cheema, Amrita K.; Mapstone, Mark E.; Fiandaca, Massimo S.; Federoff, Howard J.; Newport, Elissa L.

2015-01-01

Introduction: Seven hundred ninety-five thousand Americans will have a stroke this year, and half will have a chronic hemiparesis. Substantial animal literature suggests that the mammalian brain has much potential to recover from acute injury using mechanisms of neuroplasticity, and that these mechanisms can be accessed using training paradigms and neurotransmitter manipulation. However, most of these findings have not been tested or confirmed in the rehabilitation setting, in large part because of the challenges in translating a conceptually straightforward laboratory experiment into a meaningful and rigorous clinical trial in humans. Through presentation of methods for a Phase II trial, we discuss these issues and describe our approach. Methods: In rodents there is compelling evidence for timing effects in rehabilitation; motor training delivered at certain times after stroke may be more effective than the same training delivered earlier or later, suggesting that there is a critical or sensitive period for strongest rehabilitation training effects. If analogous critical/sensitive periods can be identified after human stroke, then existing clinical resources can be better utilized to promote recovery. The Critical Periods after Stroke Study (CPASS) is a phase II randomized, controlled trial designed to explore whether such a sensitive period exists. We will randomize 64 persons to receive an additional 20 h of upper extremity therapy either immediately upon rehab admission, 2–3 months after stroke onset, 6 months after onset, or to an observation-only control group. The primary outcome measure will be the Action Research Arm Test (ARAT) at 1 year. Blood will be drawn at up to 3 time points for later biomarker studies. Conclusion: CPASS is an example of the translation of rodent motor recovery experiments into the clinical setting; data obtained from this single site randomized controlled trial will be used to finalize the design of a Phase III trial. PMID

Critical Periods after Stroke Study: Translating animal stroke recovery experiments into a clinical trial

Directory of Open Access Journals (Sweden)

Alexander W Dromerick

2015-04-01

Full Text Available Introduction: 795,000 Americans will have a stroke this year, and half will have a chronic hemiparesis. Substantial animal literature suggests that the mammalian brain has much potential to recover from acute injury using mechanisms of neuroplasticity, and that these mechanisms can be accessed using training paradigms and neurotransmitter manipulation. However, most of these findings have not been tested or confirmed in the rehabilitation setting, in large part because of the challenges in translating a conceptually straightforward laboratory experiment into a meaningful and rigorous clinical trial in humans. Through presentation of methods for a Phase II trial, we discuss these issues and describe our approach. Methods: In rodents there is compelling evidence for timing effects in rehabilitation; motor training delivered at certain times after stroke may be more effective than the same training delivered earlier or later, suggesting that there is a critical or sensitive period for strongest rehabilitation training effects. If analogous critical/sensitive periods can be identified after human stroke, then existing clinical resources can be better utilized to promote recovery. The Critical Periods after Stroke Study (CPASS is a phase II randomized, controlled trial designed to explore whether such a sensitive period exists. We will randomize 64 persons to receive an additional 20 hours of upper extremity therapy either immediately upon rehab admission, 2-3 months after stroke onset, 6 months after onset, or to an observation-only control group. The primary outcome measure will be the Action Research Arm Test at one year. Blood will be drawn at up to 3 time points for later biomarker studies. Conclusion: CPASS is an example of the translation of rodent motor recovery experiments into the clinical setting; data obtained from this single site randomized controlled trial will be used to finalize the design of a Phase III trial.

Dosimetry at the Los Alamos Critical Experiments Facility: Past, present, and future

International Nuclear Information System (INIS)

Malenfant, R.E.

1993-10-01

Although the primary reason for the existence of the Los Alamos Critical Experiments Facility is to provide basic data on the physics of systems of fissile material, the physical arrangements and ability to provide sources of radiation have led to applications for all types of radiation dosimetry. In the broad definition of radiation phenomena, the facility has provided sources to evaluate biological effects, radiation shielding and transport, and measurements of basic parameters such as the evaluation of delayed neutron parameters. Within the last 15 years, many of the radiation measurements have been directed to calibration and intercomparison of dosimetry related to nuclear criticality safety. Future plans include (1) the new applications of Godiva IV, a bare-metal pulse assembly, for dosimetry (including an evaluation of neutron and gamma-ray room return); (2) a proposal to relocate the Health Physics Research Reactor from the Oak Ridge National Laboratory to Los Alamos, which will provide the opportunity to continue the application of a primary benchmark source to radiation dosimetry; and (3) a proposal to employ SHEBA, a low-enrichment solution assembly, for accident dosimetry and evaluation

Nuclear criticality safety guide

International Nuclear Information System (INIS)

Pruvost, N.L.; Paxton, H.C.

1996-09-01

This technical reference document cites information related to nuclear criticality safety principles, experience, and practice. The document also provides general guidance for criticality safety personnel and regulators

Nuclear criticality safety guide

Energy Technology Data Exchange (ETDEWEB)

Pruvost, N.L.; Paxton, H.C. [eds.

1996-09-01

This technical reference document cites information related to nuclear criticality safety principles, experience, and practice. The document also provides general guidance for criticality safety personnel and regulators.

Characterization of the Caliban and Prospero Critical Assemblies Neutron Spectra for Integral Measurements Experiments

Science.gov (United States)

Casoli, P.; Authier, N.; Jacquet, X.; Cartier, J.

2014-04-01

Caliban and Prospero are two highly enriched uranium metallic core reactors operated on the CEA Center of Valduc. These critical assemblies are suitable for integral experiments, such as fission yields measurements or perturbation measurements, which have been carried out recently on the Caliban reactor. Different unfolding methods, based on activation foils and fission chambers measurements, are used to characterize the reactor spectra and especially the Caliban spectrum, which is very close to a pure fission spectrum.

The effect of leadership behaviours on followers’ experiences and expectations in a safety-critical industry

Directory of Open Access Journals (Sweden)

Christiaan G. Joubert

2017-04-01

Full Text Available Background: Motivation for this study was found in concern expressed by civil aviation organisations that specialists in the air navigation services provider sector require appropriate and beneficial organisational leadership to encourage, enable and manage transformation within this highly structured setting. Also, academic research puts emphasis on a need for investigations of the roles, expectations and requirements of followers in the leadership–followership relationship. Followers’ experiences and expectations of leadership behaviours in an air navigation service provider (ANSP organisation were investigated and served as orientation and setting applicable to this study. Aim: The aim of the research was to identify and understand how follower experiences and expectations of leadership behaviours in a safety-critical commercial environment can affect leadership training and growth. The above-mentioned motivated this investigation of leadership traits and behaviours within an explicit context and from a follower’s viewpoint. Setting: The setting for the study was twenty two Air Traffic and Navigation Services Company sites where followers’ experiences and expectations of leadership behaviours in an air navigation service provider (ANSP organisation were investigated and served as orientation and setting applicable to this study. Methods: An ethnographic case study research style was adopted and followed because it allowed for an all-inclusive, holistic narrative report and interpretation. The samples for the quantitative and qualitative components of this study were parallel and methods employed addressed different aspects of the phenomenon, which allowed for a mixed methods research design. A one-way causality in the research design was observed because traits of followers that might influence leaders’ behaviours were excluded. Data were collected by means of a Leader Trait and Behaviour Questionnaire completed by participants

Criticality experiments with annular cylinders containing plutonium solutions; Experiences de criticite sur des cylindres annulaires contenant des solutions de plutonium

Energy Technology Data Exchange (ETDEWEB)

Molbert, M; Sauve, A; Houelle, M; Deilgat, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The criticality station of Dijon involves three cells, shielded by concrete walls of 1.46 meter thickness. Those cells are designed to contain the criticality experiment apparatus. The engineering building is also involving: one chemical laboratory where plutonium solutions are prepared, one analysis laboratory, several activated solutions storages, several control rooms, One cell contains the B system, which is designed to study: annular cylindrical geometries, slab of 10 cm thickness, interaction between annular cylinders. This report includes the first results given by experiments on annular cylinders defined by their own geometry (outer and inner diameter of ring containing plutonium solutions). Those results have been plotted in curves, for several concentrations and for different reflection conditions (outer or inner light water reflector, cadmium screen), H{sub c} and M{sub c} = f (c) (where H{sub c} is the critical height of solution, M{sub c} is the critical mass, c is the plutonium concentration: 42,3 g/lexperiments on this cylinder being unfinished to the date of this present report publication. On this miscellaneous results, we have following informations know: - Screen effect of light water in central hole. Strengthened effect by cadmium foil on the inside wall. - Normalized interaction curves ( {alpha}*H{sub c}/H{sub c{infinity}} ) versus the distance between the two vessels, where H{sub c{infinity}} critical height of an insulated cylinder, shows that: 1) In light water, two cylinders set aside from 15 cm, can be considers like separated. 2) For some configurations, {alpha} vary

History of critical experiments at Pajarito Site

International Nuclear Information System (INIS)

Paxton, H.C.

1983-03-01

This account describes critical and subcritical assemblies operated remotely at the Pajarito Canyon Site at the Los Alamos National Laboratory. Earliest assemblies, directed exclusively toward the nuclear weapons program, were for safety tests. Other weapon-related assemblies provided neutronic information to check detailed weapon calculations. Topsy, the first of these critical assemblies, was followed by Lady Godiva, Jezebel, Flattop, and ultimately Big Ten. As reactor programs came to Los Alamos, design studies and mockups were tested at Pajarito Site. For example, nearly all 16 Rover reactors intended for Nevada tests were preceded by zero-power mockups and proof tests at Pajarito Site. Expanded interest and capability led to fast-pulse assemblies, culminating in Godiva IV and Skua, and to the Kinglet and Sheba solution assemblies

History of critical experiments at Pajarito Site

Energy Technology Data Exchange (ETDEWEB)

Paxton, H.C.

1983-03-01

This account describes critical and subcritical assemblies operated remotely at the Pajarito Canyon Site at the Los Alamos National Laboratory. Earliest assemblies, directed exclusively toward the nuclear weapons program, were for safety tests. Other weapon-related assemblies provided neutronic information to check detailed weapon calculations. Topsy, the first of these critical assemblies, was followed by Lady Godiva, Jezebel, Flattop, and ultimately Big Ten. As reactor programs came to Los Alamos, design studies and mockups were tested at Pajarito Site. For example, nearly all 16 Rover reactors intended for Nevada tests were preceded by zero-power mockups and proof tests at Pajarito Site. Expanded interest and capability led to fast-pulse assemblies, culminating in Godiva IV and Skua, and to the Kinglet and Sheba solution assemblies.

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

IS WAITING THE HARDEST PART? A CRITICAL STUDY OF THE EXPERIENCE OF WOMEN AWAITING BREAST BIOPSY RESULTS.

Science.gov (United States)

Hodgkinson, T; Govender, C; Rayne, S

2017-06-01

Most previous research efforts have focused on the psychological effects of receiving a cancer diagnosis rather than the period of waiting for definitive Results. Early detection of cancer is directly linked to successful treatment regimes, yet these procedures evoke significant anxiety in patients. The long wait for medical test Results in state health institutions, with one of the possible outcomes being a cancer diagnosis, means that the days of waiting can induce emotional distress before the diagnosis has even been given. Eight research collaborators were invited to, in their own voice, shed light on their individual experiences while waiting for their biopsy Results to gain an understanding of the experiences of each collaborator by letting her tell her story and to explore the possibility of shared experience between collaborators. Research collaborators at a local, government hospital kept a journal for the two-week waiting period for their biopsy Results. Shortly before receiving their Results, they took part in a short semi-structured interview to inquire about their waiting. The theoretical framework used for data interpretation is critical theory focusing on the structures within society and healthcare systems that impact on the experience of waiting. The undercurrent of critical commentary about the roles of the gender, economic, political and cultural factors that contribute to the screening experience for women in South Africa helps to shed light on the complex forces at play within the procedures. The Results indicate that for some women waiting provokes significant psychological stress which manifests in multiple psychological processes including the psychological bracing phenomenon, denial, suppression and negation of their emotional experience all perpetuated by the structures of power within the health care system. More understanding of the psychological experience of awaiting a cancer diagnosis is required and there is an important place for

The analysis of FCA critical experiments and its application to ''JOYO'' nuclear design

International Nuclear Information System (INIS)

Iijima, S.

1979-01-01

A series of extensive mockup experiments in support of Japanese Experimental Fast Reactor, ''JOYO'', were performed at Fast Critical Assembly in JAERI, from February 1970 to March 1972. The present paper describes the results of analysis of these mockup experiments and its application to ''JOYO'' nuclear design. The basic calculational method of the analysis is the same as that employed in ''JOYO'' neutronics calculation, viz., the 6-group diffusion theory using 25-group NAIG Nuclear Set No. 5. Corrections to the base calculations were evaluated by using one-dimensional S 4 transport theory and integral transport theory. The ABBN group constants were also used for the sake of comparison. The most probable values of JOYO neutronics parameters were determined by applying the bias factor (E/C) to the calculated values. The uncertainties of the most probable values were also determined, and they were taken into consideration in the JOYO design

Use of integral data in the development of design methods for fast reactors

International Nuclear Information System (INIS)

Doncals, R.A.; Lake, J.A.; Paik, N.C.

1978-01-01

The paper describes an LMFBR nuclear design methodology which has been strongly influenced by the availability of integral data, by the expansion of the differential nuclear data base, by improvements in large nuclear design computer codes, and by the specific reactor under consideration. The accuracy of the nuclear data base has been improved as the result of detailed differential measurements as well as extensive integral testing in the ZPR and ZPPR criticals. Due to the increased interest in radial parfait designs, the applicability of the design data and methods to the analysis of heterogeneous LMFBR systems have been explored. The ability of the design data and methods to predict integral parameters in ZPPR is also discussed

Long-Term Soil Experiments: A Key to Managing Earth's Rapidly Changing Critical Zones

Science.gov (United States)

Richter, D., Jr.

2014-12-01

In a few decades, managers of Earth's Critical Zones (biota, humans, land, and water) will be challenged to double food and fiber production and diminish adverse effects of management on the wider environment. To meet these challenges, an array of scientific approaches is being used to increase understanding of Critical Zone functioning and evolution, and one amongst these approaches needs to be long-term soil field studies to move us beyond black boxing the belowground Critical Zone, i.e., to further understanding of processes driving changes in the soil environment. Long-term soil experiments (LTSEs) provide direct observations of soil change and functioning across time scales of decades, data critical for biological, biogeochemical, and environmental assessments of sustainability; for predictions of soil fertility, productivity, and soil-environment interactions; and for developing models at a wide range of temporal and spatial scales. Unfortunately, LTSEs globally are not in a good state, and they take years to mature, are vulnerable to loss, and even today remain to be fully inventoried. Of the 250 LTSEs in a web-based network, results demonstrate that soils and belowground Critical Zones are highly dynamic and responsive to human management. The objective of this study is to review the contemporary state of LTSEs and consider how they contribute to three open questions: (1) can soils sustain a doubling of food production in the coming decades without further impinging on the wider environment, (2) how do soils interact with the global C cycle, and (3) how can soil management establish greater control over nutrient cycling. While LTSEs produce significant data and perspectives for all three questions, there is on-going need and opportunity for reviews of the long-term soil-research base, for establishment of an efficiently run network of LTSEs aimed at sustainability and improving management control over C and nutrient cycling, and for research teams that

Sandbox rheometry: Co-evolution of stress and strain in Riedel- and Critical Wedge-experiments

Science.gov (United States)

Ritter, Malte C.; Santimano, Tasca; Rosenau, Matthias; Leever, Karen; Oncken, Onno

2018-01-01

Analogue sandbox experiments have been used for a long time to understand tectonic processes, because they facilitate detailed measurements of deformation at a spatio-temporal resolution unachievable from natural data. Despite this long history, force measurements to further characterise the mechanical evolution in analogue sandbox experiments have only emerged recently. Combined continuous measurements of forces and deformation in such experiments, an approach here referred to as "sandbox rheometry", are a new tool that may help to better understand work budgets and force balances for tectonic systems and to derive constitutive laws for regional scale deformation. In this article we present an experimental device that facilitates precise measurements of boundary forces and surface deformation at high temporal and spatial resolution. We demonstrate its capabilities in two classical experiments: one of strike-slip deformation (the Riedel set-up) and one of compressional accretionary deformation (the Critical Wedge set-up). In these we are able to directly observe a correlation between strain weakening and strain localisation that had previously only been inferred, namely the coincidence of the maximum localisation rate with the onset of weakening. Additionally, we observe in the compressional experiment a hysteresis of localisation with respect to the mechanical evolution that reflects the internal structural complexity of an accretionary wedge.

Validation of VHTRC calculation benchmark of critical experiment using the MCB code

Directory of Open Access Journals (Sweden)

Stanisz Przemysław

2016-01-01

Full Text Available The calculation benchmark problem Very High Temperature Reactor Critical (VHTR a pin-in-block type core critical assembly has been investigated with the Monte Carlo Burnup (MCB code in order to validate the latest version of Nuclear Data Library based on ENDF format. Executed benchmark has been made on the basis of VHTR benchmark available from the International Handbook of Evaluated Reactor Physics Benchmark Experiments. This benchmark is useful for verifying the discrepancies in keff values between various libraries and experimental values. This allows to improve accuracy of the neutron transport calculations that may help in designing the high performance commercial VHTRs. Almost all safety parameters depend on the accuracy of neutron transport calculation results that, in turn depend on the accuracy of nuclear data libraries. Thus, evaluation of the libraries applicability to VHTR modelling is one of the important subjects. We compared the numerical experiment results with experimental measurements using two versions of available nuclear data (ENDF-B-VII.1 and JEFF-3.2 prepared for required temperatures. Calculations have been performed with the MCB code which allows to obtain very precise representation of complex VHTR geometry, including the double heterogeneity of a fuel element. In this paper, together with impact of nuclear data, we discuss also the impact of different lattice modelling inside the fuel pins. The discrepancies of keff have been successfully observed and show good agreement with each other and with the experimental data within the 1 σ range of the experimental uncertainty. Because some propagated discrepancies observed, we proposed appropriate corrections in experimental constants which can improve the reactivity coefficient dependency. Obtained results confirm the accuracy of the new Nuclear Data Libraries.

The National Criticality Experiments Research Center at the Device Assembly Facility, Nevada National Security Site: Status and Capabilities, Summary Report

International Nuclear Information System (INIS)

Bragg-Sitton, S.; Bess, J.; Werner, J.

2011-01-01

The National Criticality Experiments Research Center (NCERC) was officially opened on August 29, 2011. Located within the Device Assembly Facility (DAF) at the Nevada National Security Site (NNSS), the NCERC has become a consolidation facility within the United States for critical configuration testing, particularly those involving highly enriched uranium (HEU). The DAF is a Department of Energy (DOE) owned facility that is operated by the National Nuclear Security Agency/Nevada Site Office (NNSA/NSO). User laboratories include the Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL). Personnel bring their home lab qualifications and procedures with them to the DAF, such that non-site specific training need not be repeated to conduct work at DAF. The NNSS Management and Operating contractor is National Security Technologies, LLC (NSTec) and the NNSS Safeguards and Security contractor is Wackenhut Services. The complete report provides an overview and status of the available laboratories and test bays at NCERC, available test materials and test support configurations, and test requirements and limitations for performing sub-critical and critical tests. The current summary provides a brief summary of the facility status and the method by which experiments may be introduced to NCERC.

Qualitative systematic review: the unique experiences of the nurse-family member when a loved one is admitted with a critical illness.

Science.gov (United States)

Giles, Tracey M; Hall, Karen L

2014-07-01

To interpret and synthesize nurse-family member experiences when a critically ill loved one is admitted to hospital. Having a family member hospitalized in a critical condition is an important stressor. When the family member is also a nurse, the provision of care is more complex, yet little research exists on this issue. Systematic review using Thomas and Harden's approach to thematic synthesis of qualitative research. Primary studies were located by searching CINAHL, Proquest, Journals@Ovid, SCOPUS, Cochrane Library and Google Scholar. No date restrictions were applied due to a lack of relevant literature. All studies that met inclusion criteria were retrieved (n = 1717) and seven met the review aim. Following critical appraisal, seven studies from 1999-2011 describing the nurse-family member's experience were reviewed and synthesized. Six characteristics of the nurse-family member experience were identified: specialized knowledge; dual-role conflicts; competing expectations; building relationships; being 'let in'; and healthcare setting. Nurse-family members experience important stressors that can negatively affect their psychological health and experience as a healthcare consumer. Nurse-family members want a different type of care than other healthcare consumers. Acknowledging nurse-family members' specialized knowledge and dual role, keeping them fully informed and allowing them to be with the patient and feel in control can reduce their fear and anxiety. Further research is needed to develop a deeper understanding of the unique experiences, challenges and needs of nurse-family members to provide them with an enhanced level of care. © 2013 John Wiley & Sons Ltd.

Evaluation of undergraduate clinical learning experiences in the subject of pediatric dentistry using critical incident technique.

Science.gov (United States)

Vyawahare, S; Banda, N R; Choubey, S; Parvekar, P; Barodiya, A; Dutta, S

2013-01-01

In pediatric dentistry, the experiences of dental students may help dental educators better prepare graduates to treat the children. Research suggests that student's perceptions should be considered in any discussion of their education, but there has been no systematic examination of India's undergraduate dental students learning experiences. This qualitative investigation aimed to gather and analyze information about experiences in pediatric dentistry from the students' viewpoint using critical incident technique (CIT). The sample group for this investigation came from all 240 3rd and 4th year dental students from all the four dental colleges in Indore. Using CIT, participants were asked to describe at least one positive and one negative experience in detail. They described 308 positive and 359 negative experiences related to the pediatric dentistry clinic. Analysis of the data resulted in the identification of four key factors related to their experiences: 1) The instructor; 2) the patient; 3) the learning process; and 4) the learning environment. The CIT is a useful data collection and analysis technique that provides rich, useful data and has many potential uses in dental education.

Contextualizing Asian American Education through Critical Race Theory: An Example of U.S. Pilipino College Student Experiences

Science.gov (United States)

Buenavista, Tracy Lachica; Jayakumar, Uma M.; Misa-Escalante, Kimberly

2009-01-01

In this article, the authors offer a CRT (critical race theory) perspective of the prevailing representation of Asian Americans in higher education research and acknowledge the importance of recent studies that have begun to challenge notions of a monolithic Asian American educational experience through an examination of differences among Asian…

From idealistic helper to enterprising learner: critical reflections on personal development through experiences from Afghanistan.

Science.gov (United States)

Wickford, Jenny; Rosberg, Susanne

2012-05-01

There is little written about the cultural, social, and ethical challenges encountered by physiotherapists engaging in development work. This article takes a critical perspective on what it means to engage in development work as an expatriate physiotherapist, through a self-critical reflection on experiences from Afghanistan. The field notes from an ethnographic study of a development project conducted in Afghanistan were analysed to explore the transformative process of personal and professional development of the development worker. The critical reflective process entailed a change in meaning perspective, described as a shift from the position of an Idealistic Helper to an Enterprising Learner. Of importance in this process were "disorienting dilemmas" that challenged personal perceptions. Critical reflection over such dilemmas led to deeper understanding facilitating the process of change. The essential lesson learned is that the baseline for understanding others is an understanding of one's own meaning perspectives and manner of participation in relation to others and their context. The insights gained have implications for physiotherapists working in development contexts, for other development workers, and for physiotherapists working with patients in clinical practice in a nondevelopment context. Exploring how to collaborate in development contexts could be done using reflective groups with expatriate and local physiotherapists and/or patients. This could lead to greater understanding of oneself, each other, and the local context.

Patients' experiences and actions when describing pain after surgery--a critical incident technique analysis.

Science.gov (United States)

Eriksson, Kerstin; Wikström, Lotta; Fridlund, Bengt; Årestedt, Kristofer; Broström, Anders

2016-04-01

Postoperative pain assessment remains a significant problem in clinical care despite patients wanting to describe their pain and be treated as unique individuals. Deeper knowledge about variations in patients' experiences and actions could help healthcare professionals to improve pain management and could increase patients' participation in pain assessments. The aim of this study was, through an examination of critical incidents, to describe patients' experiences and actions when needing to describe pain after surgery. An explorative design involving the critical incident technique was used. Patients from one university and three county hospitals in both urban and rural areas were included. To ensure variation of patients a strategic sampling was made according to age, gender, education and surgery. A total of 25 patients who had undergone orthopaedic or general surgery was asked to participate in an interview, of whom three declined. Pain experiences were described according to two main areas: "Patients' resources when in need of pain assessment" and "Ward resources for performing pain assessments". Patients were affected by their expectations and tolerance for pain. Ability to describe pain could be limited by a fear of coming into conflict with healthcare professionals or being perceived as whining. Furthermore, attitudes from healthcare professionals and their lack of adherence to procedures affected patients' ability to describe pain. Two main areas regarding actions emerged: "Patients used active strategies when needing to describe pain" and "Patients used passive strategies when needing to describe pain". Patients informed healthcare professionals about their pain and asked questions in order to make decisions about their pain situation. Selfcare was performed by distraction and avoiding pain or treating pain by themselves, while others were passive and endured pain or refrained from contact with healthcare professionals due to healthcare professionals

A journey from nuclear criticality methods to high energy density radflow experiments

Energy Technology Data Exchange (ETDEWEB)

Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-05-30

Los Alamos National Laboratory is a nuclear weapons laboratory supporting our nation's defense. In support of this mission is a high energy-density physics program in which we design and execute experiments to study radiationhydrodynamics phenomena and improve the predictive capability of our largescale multi-physics software codes on our big-iron computers. The Radflow project’s main experimental effort now is to understand why we haven't been able to predict opacities on Sandia National Laboratory's Z-machine. We are modeling an increasing fraction of the Z-machine's dynamic hohlraum to find multi-physics explanations for the experimental results. Further, we are building an entirely different opacity platform on Lawrence Livermore National Laboratory's National Ignition Facility (NIF), which is set to get results early 2017. Will the results match our predictions, match the Z-machine, or give us something entirely different? The new platform brings new challenges such as designing hohlraums and spectrometers. The speaker will recount his history, starting with one-dimensional Monte Carlo nuclear criticality methods in graduate school, radiative transfer methods research and software development for his first 16 years at LANL, and, now, radflow technology and experiments. Who knew that the real world was more than just radiation transport? Experiments aren't easy, but they sure are fun.

Critical Jostling

Directory of Open Access Journals (Sweden)

Pippin Barr

2016-11-01

Full Text Available Games can serve a critical function in many different ways, from serious games about real world subjects to self-reflexive commentaries on the nature of games themselves. In this essay we discuss critical possibilities stemming from the area of critical design, and more specifically Carl DiSalvo’s adversarial design and its concept of reconfiguring the remainder. To illustrate such an approach, we present the design and outcomes of two games, Jostle Bastard and Jostle Parent. We show how the games specifically engage with two previous games, Hotline Miami and Octodad: Dadliest Catch, reconfiguring elements of those games to create interactive critical experiences and extensions of the source material. Through the presentation of specific design concerns and decisions, we provide a grounded illustration of a particular critical function of videogames and hope to highlight this form as another valuable approach in the larger area of videogame criticism.

Critical Pedagogy: EFL Teachers' Views, Experience and Academic Degrees

Science.gov (United States)

Mahmoodarabi, Mahsa; Khodabakhsh, Mohammad Reza

2015-01-01

Although critical pedagogy has brought about positive changes in the field of education by shifting from traditional pedagogy to emancipatory pedagogy, not much attention has been paid to the factors affecting teachers' beliefs of critical pedagogy and only few studies have been conducted to design reliable and valid instruments to study EFL…

Search for the critical point of strongly interacting matter at the CERN SPS NA61/SHINE experiment

CERN Document Server

Turko, L

2015-01-01

The NA61/SHINE experiment performs a detailed study of the onset of deconfinement and search for critical point of hadronic matter by colliding nuclei of different sizes at various beam momenta from 13A to 158A GeV/c. Experimental setup and results on the theoretically expected signatures are discussed.

Analysis of ex-core detector response measured during nuclear ship Mutsu land-loaded core critical experiment

International Nuclear Information System (INIS)

Itagaki, M.; Abe, J.I.; Kuribayashi, K.

1987-01-01

There are some cases where the ex-core neutron detector response is dependent not only on the fission source distribution in a core but also on neutron absorption in the borated water reflector. For example, an unexpectedly large response variation was measured during the nuclear ship Mutsu land-loaded core critical experiment. This large response variation is caused largely by the boron concentration change associated with the change in control rod positioning during the experiment. The conventional Crump-Lee response calculation method has been modified to take into account this boron effect. The correction factor in regard to this effect has been estimated using the one-dimensional transport code ANISN. The detector response variations obtained by means of this new calculation procedure agree well with the measured values recorded during the experiment

Experience with performance based training of nuclear criticality safety engineers

International Nuclear Information System (INIS)

Taylor, R.G.

1993-01-01

For non-reactor nuclear facilities, the U.S. Department of Energy (DOE) does not require that nuclear criticality safety engineers demonstrate qualification for their job. It is likely, however, that more formalism will be required in the future. Current DOE requirements for those positions which do have to demonstrate qualification indicate that qualification should be achieved by using a systematic approach such as performance based training (PBT). Assuming that PBT would be an acceptable mechanism for nuclear criticality safety engineer training in a more formal environment, a site-specific analysis of the nuclear criticality safety engineer job was performed. Based on this analysis, classes are being developed and delivered to a target audience of newer nuclear criticality safety engineers. Because current interest is in developing training for selected aspects of the nuclear criticality safety engineer job, the analysis is incompletely developed in some areas

Experience using individually supplied heater rods in critical power testing of advanced BWR fuel

Energy Technology Data Exchange (ETDEWEB)

Majed, M.; Morback, G.; Wiman, P. [ABB Atom AB, Vasteras (Sweden)] [and others

1995-09-01

The ABB Atom FRIGG loop located in Vasteras Sweden has during the last six years given a large experience of critical power measurements for BWR fuel designs using indirectly heated rods with individual power supply. The loop was built in the sixties and designed for maximum 100 bar pressure. Testing up to the mid eighties was performed with directly heated rods using a 9 MW, 80 kA power supply. Providing test data to develop critical power correlations for BWR fuel assemblies requires testing with many radial power distributions over the full range of hydraulic conditions. Indirectly heated rods give large advantages for the testing procedure, particularly convenient for variation of individual rod power. A test method being used at Stern Laboratories (formerly Westinghouse Canada) since the early sixties, allows one fuel assembly to simulate all required radial power distributions. This technique requires reliable indirectly heated rods with independently controlled power supplies and uses insulated electric fuel rod simulators with built-in instrumentation. The FRIGG loop was adapted to this system in 1987. A 4MW power supply with 10 individual units was then installed, and has since been used for testing 24 and 25 rod bundles simulating one subbundle of SVEA-96/100 type fuel assemblies. The experience with the system is very good, as being presented, and it is selected also for a planned upgrading of the facility to 15 MW.

Understanding the Role of Critical Incidents in Relation to Self-Efficacy during Course-Embedded Preservice Teacher Field Experiences: A Qualitative Study

Science.gov (United States)

Epperly, Anna C.

2017-01-01

This qualitative, collective case study documented the development of the self-efficacy beliefs of special education preservice candidates during one semester of a course-embedded field experience in a small, private, faith-based university in the Midwest. Interviews of candidates regarding critical incidents in field experiences as documented by…

The influence of anaesthetists' experience on workload, performance and visual attention during simulated critical incidents.

Science.gov (United States)

Schulz, Christian M; Schneider, Erich; Kohlbecher, Stefan; Hapfelmeier, Alexander; Heuser, Fabian; Wagner, Klaus J; Kochs, Eberhard F; Schneider, Gerhard

2014-10-01

Development of accurate Situation Awareness (SA) depends on experience and may be impaired during excessive workload. In order to gain adequate SA for decision making and performance, anaesthetists need to distribute visual attention effectively. Therefore, we hypothesized that in more experienced anaesthetists performance is better and increase of physiological workload is less during critical incidents. Additionally, we investigated the relation between physiological workload indicators and distribution of visual attention. In fifteen anaesthetists, the increase of pupil size and heart rate was assessed in course of a simulated critical incident. Simulator log files were used for performance assessment. An eye-tracking device (EyeSeeCam) provided data about the anaesthetists' distribution of visual attention. Performance was assessed as time until definitive treatment. T tests and multivariate generalized linear models (MANOVA) were used for retrospective statistical analysis. Mean pupil diameter increase was 8.1% (SD ± 4.3) in the less experienced and 15.8% (±10.4) in the more experienced subjects (p = 0.191). Mean heart rate increase was 10.2% (±6.7) and 10.5% (±8.3, p = 0.956), respectively. Performance did not depend on experience. Pupil diameter and heart rate increases were associated with a shift of visual attention from monitoring towards manual tasks (not significant). For the first time, the following four variables were assessed simultaneously: physiological workload indicators, performance, experience, and distribution of visual attention between "monitoring" and "manual" tasks. However, we were unable to detect significant interactions between these variables. This experimental model could prove valuable in the investigation of gaining and maintaining SA in the operation theatre.

Nuclear Criticality Experimental Research Center (NCERC) Overview

Energy Technology Data Exchange (ETDEWEB)

Goda, Joetta Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Grove, Travis Justin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hayes, David Kirk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Myers, William L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sanchez, Rene Gerardo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-03-03

The mission of the National Criticality Experiments Research Center (NCERC) at the Device Assembly Facility (DAF) is to conduct experiments and training with critical assemblies and fissionable material at or near criticality in order to explore reactivity phenomena, and to operate the assemblies in the regions from subcritical through delayed critical. One critical assembly, Godiva-IV, is designed to operate above prompt critical. The Nuclear Criticality Experimental Research Center (NCERC) is our nation’s only general-purpose critical experiments facility and is only one of a few that remain operational throughout the world. This presentation discusses the history of NCERC, the general activities that makeup work at NCERC, and the various government programs and missions that NCERC supports. Recent activities at NCERC will be reviewed, with a focus on demonstrating how NCERC meets national security mission goals using engineering fundamentals. In particular, there will be a focus on engineering theory and design and applications of engineering fundamentals at NCERC. NCERC activities that relate to engineering education will also be examined.

Evaluation of undergraduate clinical learning experiences in the subject of pediatric dentistry using critical incident technique

Directory of Open Access Journals (Sweden)

S Vyawahare

2013-01-01

Full Text Available Introduction: In pediatric dentistry, the experiences of dental students may help dental educators better prepare graduates to treat the children. Research suggests that student′s perceptions should be considered in any discussion of their education, but there has been no systematic examination of India′s undergraduate dental students learning experiences. Aim: This qualitative investigation aimed to gather and analyze information about experiences in pediatric dentistry from the students′ viewpoint using critical incident technique (CIT. Study Design: The sample group for this investigation came from all 240 3 rd and 4 th year dental students from all the four dental colleges in Indore. Using CIT, participants were asked to describe at least one positive and one negative experience in detail. Results: They described 308 positive and 359 negative experiences related to the pediatric dentistry clinic. Analysis of the data resulted in the identification of four key factors related to their experiences: 1 The instructor; 2 the patient; 3 the learning process; and 4 the learning environment. Conclusion: The CIT is a useful data collection and analysis technique that provides rich, useful data and has many potential uses in dental education.

Criticality meets learning: Criticality signatures in a self-organizing recurrent neural network.

Science.gov (United States)

Del Papa, Bruno; Priesemann, Viola; Triesch, Jochen

2017-01-01

Many experiments have suggested that the brain operates close to a critical state, based on signatures of criticality such as power-law distributed neuronal avalanches. In neural network models, criticality is a dynamical state that maximizes information processing capacities, e.g. sensitivity to input, dynamical range and storage capacity, which makes it a favorable candidate state for brain function. Although models that self-organize towards a critical state have been proposed, the relation between criticality signatures and learning is still unclear. Here, we investigate signatures of criticality in a self-organizing recurrent neural network (SORN). Investigating criticality in the SORN is of particular interest because it has not been developed to show criticality. Instead, the SORN has been shown to exhibit spatio-temporal pattern learning through a combination of neural plasticity mechanisms and it reproduces a number of biological findings on neural variability and the statistics and fluctuations of synaptic efficacies. We show that, after a transient, the SORN spontaneously self-organizes into a dynamical state that shows criticality signatures comparable to those found in experiments. The plasticity mechanisms are necessary to attain that dynamical state, but not to maintain it. Furthermore, onset of external input transiently changes the slope of the avalanche distributions - matching recent experimental findings. Interestingly, the membrane noise level necessary for the occurrence of the criticality signatures reduces the model's performance in simple learning tasks. Overall, our work shows that the biologically inspired plasticity and homeostasis mechanisms responsible for the SORN's spatio-temporal learning abilities can give rise to criticality signatures in its activity when driven by random input, but these break down under the structured input of short repeating sequences.

Changing the Culture of Academic Medicine: Critical Mass or Critical Actors?

Science.gov (United States)

Helitzer, Deborah L; Newbill, Sharon L; Cardinali, Gina; Morahan, Page S; Chang, Shine; Magrane, Diane

2017-05-01

By 2006, women constituted 34% of academic medical faculty, reaching a critical mass. Theoretically, with critical mass, culture and policy supportive of gender equity should be evident. We explore whether having a critical mass of women transforms institutional culture and organizational change. Career development program participants were interviewed to elucidate their experiences in academic health centers (AHCs). Focus group discussions were held with institutional leaders to explore their perceptions about contemporary challenges related to gender and leadership. Content analysis of both data sources revealed points of convergence. Findings were interpreted using the theory of critical mass. Two nested domains emerged: the individual domain included the rewards and personal satisfaction of meaningful work, personal agency, tensions between cultural expectations of family and academic roles, and women's efforts to work for gender equity. The institutional domain depicted the sociocultural environment of AHCs that shaped women's experience, both personally and professionally, lack of institutional strategies to engage women in organizational initiatives, and the influence of one leader on women's ascent to leadership. The predominant evidence from this research demonstrates that the institutional barriers and sociocultural environment continue to be formidable obstacles confronting women, stalling the transformational effects expected from achieving a critical mass of women faculty. We conclude that the promise of critical mass as a turning point for women should be abandoned in favor of "critical actor" leaders, both women and men, who individually and collectively have the commitment and power to create gender-equitable cultures in AHCs.

Analysis of mixed oxide fuel critical experiments with neutronics analysis codes for boiling water reactors

International Nuclear Information System (INIS)

Tamitani, Masashi; Maruyama, Hiromi; Ishii, Kazuya; Izutsu, Sadayuki; Yamaguchi, Masao

2000-01-01

Critical experiments of UO 2 and full mixed oxide (MOX) fuel cores conducted at the Tank-type Critical Assembly (TCA) were analyzed using BWR design-purpose codes HINES and CERES with ENDF/B files and Monte Carlo fine analysis codes VMONT and MVP with the JENDL-3.2 library. The averaged values of the multiplication factors calculated with HINES/CERES, VMONT and MVP agreed with those of experiments within 0.3%Δk. The values by the design-purpose codes showed a small difference of 0.1%Δk between UO 2 and MOX cores. Monte Carlo code results showed that the JENDL-3.2 library had a tendency to overestimate the multiplication factors of UO 2 cores by about 0.3%Δk compared with those values of MOX cores. The root mean square errors of calculated power distributions were less than 1% for HINES/CERES and VMONT. These results showed that (1) the accuracy of these codes when applied to full MOX cores was almost the same as their accuracy for UO 2 cores, which confirmed the accuracy of present core design codes for full MOX cores; and (2) the accuracy of the 190-energy-group Monte Carlo calculation code VMONT was almost the same as that of the continuous-energy Monte Carlo calculation code MVP. (author)

A journey from nuclear criticality methods to high energy density radflow experiments

Energy Technology Data Exchange (ETDEWEB)

Urbatsch, Todd James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-11-08

Los Alamos National Laboratory is a nuclear weapons laboratory supporting our nation's defense. In support of this mission is a high energy-density physics program in which we design and execute experiments to study radiationhydrodynamics phenomena and improve the predictive capability of our largescale multi-physics software codes on our big-iron computers. The Radflow project’s main experimental effort now is to understand why we haven't been able to predict opacities on Sandia National Laboratory's Z-machine. We are modeling an increasing fraction of the Z-machine's dynamic hohlraum to find multi-physics explanations for the experimental results. Further, we are building an entirely different opacity platform on Lawrence Livermore National Laboratory's National Ignition Facility (NIF), which is set to get results early 2017. Will the results match our predictions, match the Z-machine, or give us something entirely different? The new platform brings new challenges such as designing hohlraums and spectrometers. The speaker will recount his history, starting with one-dimensional Monte Carlo nuclear criticality methods in graduate school, radiative transfer methods research and software development for his first 16 years at LANL, and, now, radflow technology and experiments. Who knew that the real world was more than just radiation transport? Experiments aren't easy and they are as saturated with politics as a presidential election, but they sure are fun.

Sports Management for Sports Massification Planned and Executed by Social Organizations. Critics to Models, Experiences and Proposal Methodological Accompaniment

OpenAIRE

Lorenza Antonia Reyes de Duran

2016-01-01

The proposal analysis, interpretation, disassembly, self-criticism and guidance is born and comes from work experience planned mass sports and social organizations opposed-not in the conventional sense comparative-private business models and sport, state and management. The contribution made by the sports management experience from positions of power, either state or business are undeniable and its impact is difficult to express in numbers for its humanistic value, which is incalculable. Howe...

Safety analysis of the Los Alamos critical experiments facility

International Nuclear Information System (INIS)

Paxton, H.C.

1975-10-01

The safety of Pajarito Site critical assembly operations depends upon protection built into the facility, upon knowledgeable personnel, and upon good practice as defined by operating procedures and experimental plans. Distance, supplemented by shielding in some cases, would protect personnel against an extreme accident generating 10 19 fissions. During the facility's 28-year history, the direct cost of criticality accidents has translated to a risk of less than $200 per year

Experiments for IFR fuel criticality in ZPPR-21

International Nuclear Information System (INIS)

Olsen, D.N.; Collins, P.J.; Carpenter, S.G.

1991-01-01

A series of benchmark measurements was made in ZPPR-21 to validate criticality calculations for fuel processing operations for Argonne's Integral Fast Reactor program. Six different mixtures of Pu/U/Zr fuel with a graphite reflector were built and criticality was determined by period measurements. The assemblies were isolated from room return neutrons by a lithium hydride shield. Analysis was done using a fully-detailed model with the VIM Monte Carlo code and ENDF/B-V.2 data. Sensitivity analysis was used to validate the measurements against other benchmark data. A simple RZ model was defined and used with the KENO code. Corrections to the RZ model were provided by the VIM calculations with low statistical uncertainty. (Author)

Validation study of the reactor physics lattice transport code WIMSD-5B by TRX and BAPL critical experiments of light water reactors

International Nuclear Information System (INIS)

Khan, M.J.H.; Alam, A.B.M.K.; Ahsan, M.H.; Mamun, K.A.A.; Islam, S.M.A.

2015-01-01

Highlights: • To validate the reactor physics lattice code WIMSD-5B by this analysis. • To model TRX and BAPL critical experiments using WIMSD-5B. • To compare the calculated results with experiment and MCNP results. • To rely on WIMSD-5B code for TRIGA calculations. - Abstract: The aim of this analysis is to validate the reactor physics lattice transport code WIMSD-5B by TRX (thermal reactor-one region lattice) and BAPL (Bettis Atomic Power Laboratory-one region lattice) critical experiments of light water reactors for neutronics analysis of 3 MW TRIGA Mark-II research reactor at AERE, Dhaka, Bangladesh. This analysis is achieved through the analysis of integral parameters of five light water reactor critical experiments TRX-1, TRX-2, BAPL-UO 2 -1, BAPL-UO 2 -2 and BAPL-UO 2 -3 based on evaluated nuclear data libraries JEFF-3.1 and ENDF/B-VII.1. In integral measurements, these experiments are considered as standard benchmark lattices for validating the reactor physics lattice transport code WIMSD-5B as well as evaluated nuclear data libraries. The integral parameters of the said critical experiments are calculated using the reactor physics lattice transport code WIMSD-5B. The calculated integral parameters are compared to the measured values as well as the earlier published MCNP results based on the Chinese evaluated nuclear data library CENDL-3.0 for assessment of deterministic calculation. It was found that the calculated integral parameters give mostly reasonable and globally consistent results with the experiment and the MCNP results. Besides, the group constants in WIMS format for the isotopes U-235 and U-238 between two data files have been compared using WIMS library utility code WILLIE and it was found that the group constants are well consistent with each other. Therefore, this analysis reveals the validation study of the reactor physics lattice transport code WIMSD-5B based on JEFF-3.1 and ENDF/B-VII.1 libraries and can also be essential to

Experiences of four parents with physical therapy and early mobility of their children in a pediatric critical care unit: A case series.

Science.gov (United States)

Parisien, Rachel B; Gillanders, Kirstie; Hennessy, Erin K; Herterich, Lisa; Saunders, Kendra; Lati, Jamil; Dos Santos, Stephanie; Hassall, Alison; O'Brien, Kelly K

2016-05-31

The aim of this study was to conduct a preliminary investigation into parents' experiences of physical therapy and early mobility (EM) for their children in a pediatric critical care unit (PCCU). We conducted a series of four qualitative case studies using in-depth semi-structured face-to-face interviews. We recruited parents of children who had undergone surgery and received at least one EM physical therapy intervention while intubated. We conducted a thematic analysis of transcribed interviews to illuminate the factors that influenced EM experiences. Four parents participated in the study. We developed an overview of Parental Experiences with Physical Therapy and Early Mobility in a PCCU, which includes four themes that parents believed influenced their experiences: (1) environmental factors; (2) awareness of physical therapist and health care professional (HCP) roles; (3) communication among parents and HCPs; and (4) parental participation in their child's EM, within the overarching parental experiences in the PCCU. This study affords a preliminary understanding of parents' experiences with physical therapy and EM in a PCCU setting. Results provide an important foundation for future research on mobility in the context of pediatric critical care research and practice.

Program of critical experiment and measurements at the RA reactor; Program kriticnih eksperimenata i merenja na reaktoru RA

Energy Technology Data Exchange (ETDEWEB)

NONE

1960-04-14

Program described in this document describes in detail the following experiments: critical experiments with two reactor core lattices with 38 and 44 fuel channels, initial heavy water level being 1300 mm, criticality is achieved by adding heavy water; preliminary analysis of heavy water quality and verification of the fuel isotopic contents; experiment with the initial core which contains 56 fuel channels with maximum heavy water level according to the Russian proposal; measurement of neutron flux by Dy and In foils; measurement of reactivity excess dependent on the heavy water level and number of fuel rods; measurement of reactor period for determined reactivity change; measurement of moderator temperature coefficient; measurement of absolute flux. [Serbo-Croat] Program sadrzan u ovom dokumentu opisuje detaljno sledece eksperimente: kriticni eksperiment sa dve konfiguracije jezgra reaktora, sa 38 i 44 gorivna kanala, pocetni nivo teske vode je 1300 mm, kriticnost se dostize dodavanjem teske vode; prethodno izvrsenom analizom teske vode i proverom izotopskog sastava goriva; eksperiment sa pocetnom resetkom koja prema ruskom predlogu sadrzi 56 gorivnih kanala i maksimalnom visinom teske vode; merenje raspodele neutronskog fluksa folijama Dy i In; kalibracija regulacionih sipki; merenje viska reaktivnosti sa promenom visine nivoa teske vode i promenom broja sipki; merenje periode reaktora za odredjenu promenu reaktivnosti; merenje temperaturnog koeficijenta za vodu; merenje apsolutnog fluksa.

A Course in Critical Thinking for PhD Students in Biomolecular Sciences and Biotechnology: Classical Experiments in Biochemistry

Directory of Open Access Journals (Sweden)

Carlos B. Hirschberg

2016-03-01

Full Text Available This essay presents and discusses an eight-session seminar course designed to develop critical thinking skills in doctoral biochemistry students by exposing them to classical experiments in biochemistry. During each 2.5 session, different key topics of the discovery and development of biochemical concepts are discussed. Before each session, students are required to read the one or two classical papers. The size of the seminar course and the seating of the students are critical to make this a highly interactive environment for all students to participate in the critique and re-designing of key experiments, including control experiments, which helped formulate these classical concepts. Final student evaluation of the course’s goals has two equal components: Course participation and a final take home exam due two weeks after the course is completed. Together with the take home exam students are also required to write an evaluation of the course, preferably no longer than half a page. Students’ comments of the course have been uniformly positive. The author notes the sooner students are exposed to this manner of thinking, the better they will be equipped to choose an appropriate mentor and contribute creatively to attempt to solve the scientific problem of their PhD thesis.

Summary of ORSphere critical and reactor physics measurements

Directory of Open Access Journals (Sweden)

Marshall Margaret A.

2017-01-01

Full Text Available In the early 1970s Dr. John T. Mihalczo (team leader, J.J. Lynn, and J.R. Taylor performed experiments at the Oak Ridge Critical Experiments Facility (ORCEF with highly enriched uranium (HEU metal (called Oak Ridge Alloy or ORALLOY to recreate GODIVA I results with greater accuracy than those performed at Los Alamos National Laboratory in the 1950s. The purpose of the Oak Ridge ORALLOY Sphere (ORSphere experiments was to estimate the unreflected and unmoderated critical mass of an idealized sphere of uranium metal corrected to a density, purity, and enrichment such that it could be compared with the GODIVA I experiments. This critical configuration has been evaluated. Preliminary results were presented at ND2013. Since then, the evaluation was finalized and judged to be an acceptable benchmark experiment for the International Criticality Safety Benchmark Experiment Project (ICSBEP. Additionally, reactor physics measurements were performed to determine surface button worths, central void worth, delayed neutron fraction, prompt neutron decay constant, fission density and neutron importance. These measurements have been evaluated and found to be acceptable experiments and are discussed in full detail in the International Handbook of Evaluated Reactor Physics Benchmark Experiments. The purpose of this paper is to summarize all the evaluated critical and reactor physics measurements evaluations.

Summary of ORSphere critical and reactor physics measurements

Science.gov (United States)

Marshall, Margaret A.; Bess, John D.

2017-09-01

In the early 1970s Dr. John T. Mihalczo (team leader), J.J. Lynn, and J.R. Taylor performed experiments at the Oak Ridge Critical Experiments Facility (ORCEF) with highly enriched uranium (HEU) metal (called Oak Ridge Alloy or ORALLOY) to recreate GODIVA I results with greater accuracy than those performed at Los Alamos National Laboratory in the 1950s. The purpose of the Oak Ridge ORALLOY Sphere (ORSphere) experiments was to estimate the unreflected and unmoderated critical mass of an idealized sphere of uranium metal corrected to a density, purity, and enrichment such that it could be compared with the GODIVA I experiments. This critical configuration has been evaluated. Preliminary results were presented at ND2013. Since then, the evaluation was finalized and judged to be an acceptable benchmark experiment for the International Criticality Safety Benchmark Experiment Project (ICSBEP). Additionally, reactor physics measurements were performed to determine surface button worths, central void worth, delayed neutron fraction, prompt neutron decay constant, fission density and neutron importance. These measurements have been evaluated and found to be acceptable experiments and are discussed in full detail in the International Handbook of Evaluated Reactor Physics Benchmark Experiments. The purpose of this paper is to summarize all the evaluated critical and reactor physics measurements evaluations.

Caring for patients of Islamic denomination: Critical care nurses' experiences in Saudi Arabia.

Science.gov (United States)

Halligan, Phil

2006-12-01

To describe the critical care nurses' experiences in caring for patients of Muslim denomination in Saudi Arabia. Caring is known to be the essence of nursing but many health-care settings have become more culturally diverse. Caring has been examined mainly in the context of Western cultures. Muslims form one of the largest ethnic minority communities in Britain but to date, empirical studies relating to caring from an Islamic perspective is not well documented. Research conducted within the home of Islam would provide essential truths about the reality of caring for Muslim patients. Phenomenological descriptive. Methods. Six critical care nurses were interviewed from a hospital in Saudi Arabia. The narratives were analysed using Colaizzi's framework. The meaning of the nurses' experiences emerged as three themes: family and kinship ties, cultural and religious influences and nurse-patient relationship. The results indicated the importance of the role of the family and religion in providing care. In the process of caring, the participants felt stressed and frustrated and they all experienced emotional labour. Communicating with the patients and the families was a constant battle and this acted as a further stressor in meeting the needs of their patients. The concept of the family and the importance and meaning of religion and culture were central in the provision of caring. The beliefs and practices of patients who follow Islam, as perceived by expatriate nurses, may have an effect on the patient's health care in ways that are not apparent to many health-care professionals and policy makers internationally. Readers should be prompted to reflect on their clinical practice and to understand the impact of religious and cultural differences in their encounters with patients of Islam denomination. Policy and all actions, decisions and judgments should be culturally derived.

The critical ionization velocity

International Nuclear Information System (INIS)

Raadu, M.A.

1980-06-01

The critical ionization velocity effect was first proposed in the context of space plasmas. This effect occurs for a neutral gas moving through a magnetized plasma and leads to rapid ionization and braking of the relative motion when a marginal velocity, 'the critical velocity', is exceeded. Laboratory experiments have clearly established the significance of the critical velocity and have provided evidence for an underlying mechanism which relies on the combined action of electron impact ionization and a collective plasma interaction heating electrons. There is experimental support for such a mechanism based on the heating of electrons by the modified two-stream instability as part of a feedback process. Several applications to space plasmas have been proposed and the possibility of space experiments has been discussed. (author)

Improved set of criticality accident detectors used in the intercomparison experiment in Valduc

International Nuclear Information System (INIS)

Jozefowicz, K.; Golnik, N.

1996-01-01

An improved set of critically accident detectors has been elaborated for the needs of the Inst. of Atomic Energy in Swierk. The sets, which consist of fission track detectors, wide-base silicon diodes and RPL glasses, were tested in the international intercomparison experiment in Valduc, France. Comparison of our results with the reference measurements showed a good agreement (within 25%) for both the neutron and gamma measurements. Additionally, the diode response to neutron kerma was investigated more extensively in the dose range between 2 and 10 Gy, where the dependence of the diode signal versus neutron kerma was not well known. A possibility of the multiple use of the diodes has been proved. (author)

Summary of ORSphere Critical and Reactor Physics Measurements

Energy Technology Data Exchange (ETDEWEB)

Marshall, Margaret A.; Bess, John D.

2016-09-01

In the early 1970s Dr. John T. Mihalczo (team leader), J. J. Lynn, and J. R. Taylor performed experiments at the Oak Ridge Critical Experiments Facility (ORCEF) with highly enriched uranium (HEU) metal (called Oak Ridge Alloy or ORALLOY) to recreate GODIVA I results with greater accuracy than those performed at Los Alamos National Laboratory in the 1950s. The purpose of the Oak Ridge ORALLOY Sphere (ORSphere) experiments was to estimate the unreflected and unmoderated critical mass of an idealized sphere of uranium metal corrected to a density, purity, and enrichment such that it could be compared with the GODIVA I experiments. This critical configuration has been evaluated. Preliminary results were presented at ND2013. Since then, the evaluation was finalized and judged to be an acceptable benchmark experiment for the International Criticality Safety Benchmark Experiment Project (ICSBEP). Additionally, reactor physics measurements were performed to determine surface button worths, central void worth, delayed neutron fraction, prompt neutron decay constant, fission density and neutron importance. These measurements have been evaluated and found to be acceptable experiments and are discussed in full detail in the International Handbook of Evaluated Reactor Physics Benchmark Experiments. The purpose of this paper is summary summarize all the critical and reactor physics measurements evaluations and, when possible, to compare them to GODIVA experiment results.

Experiments for IFR fuel criticality in ZPPR-21

International Nuclear Information System (INIS)

Olsen, D.N.; Collins, P.J.; Carpenter, S.G.

1991-01-01

A series of benchmark measurements was made in ZPPR-21 to validate criticality calculations for fuel operations in Argonne's Integral Fast Reactor. Six different mixtures of Pu/U/Zr fuel with a graphite reflector were built and criticality was determined by period measurements. The assemblies were isolated from room return problems by a lithium hydride shield. Analysis was done using a fully-detailed model with the VIM Monte Carlo code and ENDF/B-V.2 data. Sensitivity analysis was used to validate the measurements against other benchmark data. A simple RZ model was defined the used with the KENO code. Corrections to the RZ model were provided by the VIM calculations with low statistical uncertainty. 7 refs., 5 figs., 5 tabs

Validation of the ABBN/CONSYST constants system. Part 2: Validation through the critical experiments on cores with uranium solutions

International Nuclear Information System (INIS)

Ivanova, T.T.; Manturov, G.N.; Nikolaev, M.N.; Rozhikhin, E.V.; Semenov, M.Yu.; Tsiboulia, A.M.

1999-01-01

Results of calculations of critical assemblies with the cores of uranium solutions for the considered series of the experiments are presented in this paper. The conclusions about acceptability of the ABBN-93.1 cross sections for the calculations of such systems are made. (author)

Danish parents' experiences when their newborn or critically ill child is transferred to the PICU - a qualitative study

DEFF Research Database (Denmark)

Hall, Elisabeth

2005-01-01

The aim of this study was to describe Danish parents' experiences when their newborn or small child was critically ill. Thirteen parents were interviewed. Data were analyzed using qualitative content analysis. The child's transfer to the paediatric intensive care unit (PICU) meant either help...... or death for the parents. The back transfer was experienced as joy and despair. The parents had confidence in most nurses, and they were kind, helpful, informative and capable. Less capable and distressed nurses made the parents feel uncomfortale and insecure. Parents need help and support during...... their child's transfer to and from the PICU. Critical care nurses have to discuss the policy of family-centred care....

Changing the Culture of Academic Medicine: Critical Mass or Critical Actors?

Science.gov (United States)

Newbill, Sharon L.; Cardinali, Gina; Morahan, Page S.; Chang, Shine; Magrane, Diane

2017-01-01

Abstract Purpose: By 2006, women constituted 34% of academic medical faculty, reaching a critical mass. Theoretically, with critical mass, culture and policy supportive of gender equity should be evident. We explore whether having a critical mass of women transforms institutional culture and organizational change. Methods: Career development program participants were interviewed to elucidate their experiences in academic health centers (AHCs). Focus group discussions were held with institutional leaders to explore their perceptions about contemporary challenges related to gender and leadership. Content analysis of both data sources revealed points of convergence. Findings were interpreted using the theory of critical mass. Results: Two nested domains emerged: the individual domain included the rewards and personal satisfaction of meaningful work, personal agency, tensions between cultural expectations of family and academic roles, and women's efforts to work for gender equity. The institutional domain depicted the sociocultural environment of AHCs that shaped women's experience, both personally and professionally, lack of institutional strategies to engage women in organizational initiatives, and the influence of one leader on women's ascent to leadership. Conclusions: The predominant evidence from this research demonstrates that the institutional barriers and sociocultural environment continue to be formidable obstacles confronting women, stalling the transformational effects expected from achieving a critical mass of women faculty. We conclude that the promise of critical mass as a turning point for women should be abandoned in favor of “critical actor” leaders, both women and men, who individually and collectively have the commitment and power to create gender-equitable cultures in AHCs. PMID:28092473

Evaluation of nuclear characteristics of minor actinide loaded core. Analyses of BFS-69 and BFS-66-2 critical experiments

International Nuclear Information System (INIS)

Hazama, Taira; Sato, Wakaei

2010-09-01

Collaboration with Russian Institute of Physics and Power Engineering named 'Investigation of neutronic-physical characteristics and their change when introducing large quantity of neptunium (Np) at different BFS critical assemblies' has been accomplished. This is the second report of the collaboration to describe experimental information and analysis results on BFS-69 and BFS-66-2 critical experiments. In the experiments, various nuclear characteristics were measured in 2 kinds of cores with/without Np loading of about 8 kg. JAEA's standard analysis results were presented with four kinds of nuclear data (JENDL-3.2, JENDL-3.3, JENDL/AC-2008, and ENDF/BVII). Analytical results show: 1) An overestimation trend has been observed in BFS-69 criticality results, especially with JENDL-3.3 and JENDL/AC-2008. The difference from ENDF/B-II having better results mainly lies in the average cosine of the scattering angle around 1 MeV. 2) A small discrepancy exists in BFS-69 Na void reactivity results with the three JENDL nuclear data. The difference from ENDF/B-II mainly lies in scattering cross sections of sodium around 1 MeV and fission cross section of 239 Pu around 1 keV. 3) The analysis results simulate measured Np effects on nuclear characteristics within experimental errors. (author)

PREPP criticality control

International Nuclear Information System (INIS)

Cargo, C.H.; Becker, G.K.; Berglund, G.R.; O'Connor, N.J.

1989-03-01

There is a general lack of data available with regards to criticality control in the use of incineration for full scale processing of TRU waste. In addition to the new analytical tools, such as PRA, are only now starting to be applied to criticality control. These factors have made the development of the PREPP Criticality Control Plan somewhat unique. It is hoped that the PREPP experiences gained in these efforts will provide new insight which will be useful to future facilities processing waste material containing fissile material. 1 fig

Critical opalescence in baryonic QCD matter.

Science.gov (United States)

Antoniou, N G; Diakonos, F K; Kapoyannis, A S; Kousouris, K S

2006-07-21

We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies.

Critical Opalescence in Baryonic QCD Matter

Science.gov (United States)

Antoniou, N. G.; Diakonos, F. K.; Kapoyannis, A. S.; Kousouris, K. S.

2006-07-01

We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies.

Critical Opalescence in Baryonic QCD Matter

International Nuclear Information System (INIS)

Antoniou, N. G.; Diakonos, F. K.; Kapoyannis, A. S.; Kousouris, K. S.

2006-01-01

We show that critical opalescence, a clear signature of second-order phase transition in conventional matter, manifests itself as critical intermittency in QCD matter produced in experiments with nuclei. This behavior is revealed in transverse momentum spectra as a pattern of power laws in factorial moments, to all orders, associated with baryon production. This phenomenon together with a similar effect in the isoscalar sector of pions (sigma mode) provide us with a set of observables associated with the search for the QCD critical point in experiments with nuclei at high energies

Measuring the coefficient of restitution and more: a simple experiment to promote students’ critical thinking and autonomous work

Science.gov (United States)

González, Manuel Á.; González, Miguel Á.; Vegas, Jesús; Llamas, César

2017-09-01

A simple experiment on the determination of the coefficient of restitution of different materials is taken as the basis of an extendable work that can be done by students in an autonomous way. On the whole, the work described in this paper would involve concepts of kinematics, materials science, air drag and buoyancy, and would help students to think of physics as a whole subject instead of a set of, more or less, isolated parts. The experiment can be done either in teaching laboratories or as an autonomous work by students at home. Students’ smartphones and cheap balls of different materials are the only experimental materials required to do the experiment. The proposed work also permits the students to analyse the limitations of a physical model used in the experiment by analysing the approximations considered in it, and then enhancing their critical thinking.

College Students' Experiences with Diversity and Their Effects on Academic Self-Confidence, Social Agency, and Disposition toward Critical Thinking

Science.gov (United States)

Laird, Thomas F. Nelson

2005-01-01

The results of this study conducted at the University of Michigan (n = 289) indicate that students with more experiences with diversity, particularly enrollment in diversity courses and positive interactions with diverse peers, are more likely to score higher on academic self-confidence, social agency, and critical thinking disposition. In…

Near-critical density filling of the SF6 fluid cell for the ALI-R-DECLIC experiment in weightlessness

Science.gov (United States)

Lecoutre, C.; Marre, S.; Garrabos, Y.; Beysens, D.; Hahn, I.

2018-05-01

Analyses of ground-based experiments on near-critical fluids to precisely determine their density can be hampered by several effects, especially the density stratification of the sample, the liquid wetting behavior at the cell walls, and a possible singular curvature of the "rectilinear" diameter of the density coexisting curve. For the latter effect, theoretical efforts have been made to understand the amplitude and shape of the critical hook of the density diameter, which depart from predictions from the so-called ideal lattice-gas model of the uniaxial 3D-Ising universality class. In order to optimize the observation of these subtle effects on the position and shape of the liquid-vapor meniscus in the particular case of SF6, we have designed and filled a cell that is highly symmetrized with respect to any median plane of the total fluid volume. In such a viewed quasi-perfect symmetrical fluid volume, the precise detection of the meniscus position and shape for different orientations of the cell with respect to the Earth's gravity acceleration field becomes a sensitive probe to estimate the cell mean density filling and to test the singular diameter effects. After integration of this cell in the ALI-R insert, we take benefit of the high optical and thermal performances of the DECLIC Engineering Model. Here we present the sensitive imaging method providing the precise ground-based SF6 benchmark data. From these data analysis it is found that the temperature dependence of the meniscus position does not reflect the expected critical hook in the rectilinear density diameter. Therefore the off-density criticality of the cell is accurately estimated, before near future experiments using the same ALI-R insert in the DECLIC facility already on-board the International Space Station.

The trajectory of experience of critical care nurses in providing end-of-life care: A qualitative descriptive study.

Science.gov (United States)

Ong, Keh Kiong; Ting, Kit Cheng; Chow, Yeow Leng

2018-01-01

To understand the perceptions of critical care nurses towards providing end-of-life care. There has been an increasing interest in end-of-life care in the critical care setting. In Singapore, approximately half of deaths in the hospital occur during critical care. While nurses are well positioned to provide end-of-life care to patients and their family members, they faced barriers to providing end-of-life care. Also, providing end-of-life care has profound positive and negative psychological effects on nurses, with the latter being more prominent. Qualitative descriptive design. Data collection was performed in a medical intensive care unit of a public tertiary hospital in Singapore. Ten registered nurses were purposively sampled and interviewed individually using a semi-structured interview guide. A codebook was developed to guide coding, and data were thematically analysed. Rigour was maintained. Nurses went through a trajectory of experience. They experienced the culture of care and developed dissatisfaction with it. The tension shaped their perception and meaning of life and death, and they developed mechanisms to reach resolution. This study provides insight on nurses' perception as a trajectory of experience and raised several implications on clinical practice, policy and research. There is a need to alleviate the tension nurses face and to facilitate coming to terms with the tension by improving the culture of care and supporting nurses. Nurses could be involved more in decision-making and empowered to start end-of-life care conversations within the team and with family members. Communication with family members and between nurses and doctors could be improved. Support for nurses providing end-of-life care could be enhanced through promoting social networks, education and bereavement support. Further research is needed to explore ways to support and empower nurses to provide end-of-life care in critical care. © 2017 John Wiley & Sons Ltd.

Comparative study on neutron data in integral experiments of MYRRHA mockup critical cores in the VENUS-F reactor

Directory of Open Access Journals (Sweden)

Krása Antonín

2017-01-01

Full Text Available VENUS-F is a fast, zero-power reactor with 30% wt. metallic uranium fuel and solid lead as coolant simulator. It serves as a mockup of the MYRRHA reactor core. This paper describes integral experiments performed in two critical VENUS-F core configurations (with and without graphite reflector. Discrepancies between experiments and Monte Carlo calculations (MCNP5 of keff, fission rate spatial distribution and reactivity effects (lead void and fuel Doppler depending on a nuclear data library used (JENDL-4.0, ENDF-B-VII.1, JEFF-3.1.2, 3.2, 3.3T2 are presented.

Comparative study on neutron data in integral experiments of MYRRHA mockup critical cores in the VENUS-F reactor

Science.gov (United States)

Krása, Antonín; Kochetkov, Anatoly; Baeten, Peter; Vittiglio, Guido; Wagemans, Jan; Bécares, Vicente

2017-09-01

VENUS-F is a fast, zero-power reactor with 30% wt. metallic uranium fuel and solid lead as coolant simulator. It serves as a mockup of the MYRRHA reactor core. This paper describes integral experiments performed in two critical VENUS-F core configurations (with and without graphite reflector). Discrepancies between experiments and Monte Carlo calculations (MCNP5) of keff, fission rate spatial distribution and reactivity effects (lead void and fuel Doppler) depending on a nuclear data library used (JENDL-4.0, ENDF-B-VII.1, JEFF-3.1.2, 3.2, 3.3T2) are presented.

Comparison of MCNP and WIMS-AECL/RFSP calculations against critical heavy water experiments in ZED-2 with CANFLEX-LVRF and CANFLEX-LEU fuels

International Nuclear Information System (INIS)

Bromley, B. P.; Watts, D. G.; Pencer, J.; Zeller, M.; Dweiri, Y.

2009-01-01

This paper summarizes calculations of MCNP5 and WIMS-AECL/RFSP compared against measurements in coolant void substitution experiments in the ZED-2 critical facility with CANFLEX R-LEU/RU (Low Enriched Uranium, Recovered Uranium) reference fuels and CANFLEX-LVRF (Low Void Reactivity Fuel) test fuel, and H 2 O/air coolants. Both codes are tested for the prediction of the change in reactivity with complete voiding of all fuel channels, and that for a checkerboard voiding pattern. Understanding these phenomena is important for the ACR-1000 R reactor. Comparisons are also made for the prediction of the axial and radial neutron flux distributions, as measured by copper foil activation. The experimental data for these comparisons were obtained from critical mixed lattice / substitution experiments in AECL's ZED-2 critical facility using CANFLEX-LEU/RU and CANFLEX-LVRF fuel in a 24-cm square lattice pitch at 25 degrees C. Substitution analyses were performed to isolate the properties (buckling, bare critical lattice dimensions) of the CANFLEX-LVRF fuel. This data was then used to further test the lattice physics codes. These comparisons establish biases/uncertainties and errors in the calculation of k eff , coolant void reactivity, checkerboard coolant void reactivity, and flux distributions. Results show small to modest biases in void reactivity and very good agreement for flux distributions. The importance of boundary conditions and the modeling of un-moderated fuel in the critical experiments are demonstrated. This comparison study provides data that supports code validation and gives good confidence in the reactor physics tools used in the design and safety analysis of the ACR-1000 reactor. (authors)

The physics design of EBR-II; Physique du reacteur EBR-II; Fizicheskij raschet ehksperimental'nogo reaktora - razmnozhitelya EVR-II; Aspectos fisicos del reactor EBR-II

Energy Technology Data Exchange (ETDEWEB)

Loewenstein, W. B. [Argonne National Laboratory, Argonne, IL (United States)

1962-03-15

The physics design oi EBR-II. Calculations of the static, dynamic and long-term reactivity behaviour of EBR-II are reported together with results and analysis of EBR-II dry critical and ZPR-III mock-up experiments. Particular emphasis is given to reactor-physics design problems which arise after the conceptual design is established and before the reactor is built or placed into operation. Reactor-safety analyses and hazards-evaluation considerations are described with their influence on the reactor design. The manner of utilizing the EBR-II mock-up on ZPR-III data and the EBR-II dry critical data is described. These experiments, their analysis and theoretical predictions are the basis for predetermining the physics behaviour of the reactor system. The limitations inherent in applying the experimental data to the performance of the power-reactor system are explored in some detail. This includes the specification of reactor core size and/or fuel-alloy enrichment, provisions for adequate operating and shut-down reactivity, determination of operative temperature and power coefficients of reactivity, and details of power- and flux-distribution as a function of position within the reactor structure. The overall problem of transferring information from simple idealized analytical or experimental geometry to actual hexagonal reactor geometry is described. Nuclear performance, including breeding, of the actual reactor system is compared with that of the idealized conceptual system. The long-term reactivity and power behaviour of the reactor blanket is described within the framework of the proposed cycling of the fuel and blanket alloy. Safety considerations, including normal and abnormal rates of reactivity-insertion, the implication of postulated reactivity effects based on the physical behaviour of the fuel alloy and reactor structure as well as extrapolation of TREAT experiments to the EBR-II system are analysed. The EBR-II core melt-down problem is reviewed. (author

Growth and Expansion of the International Criticality Safety Benchmark Evaluation Project and the Newly Organized International Reactor Physics Experiment Evaluation Project

International Nuclear Information System (INIS)

J. Blair Briggs; Lori Scott; Yolanda Rugama; Enrico Satori

2007-01-01

Since ICNC 2003, the International Criticality Safety Benchmark Evaluation Project (ICSBEP) has continued to expand its efforts and broaden its scope. Criticality-alarm/shielding type benchmarks and fundamental physics measurements that are relevant to criticality safety applications are not only included in the scope of the project, but benchmark data are also included in the latest version of the handbook. A considerable number of improvements have been made to the searchable database, DICE and the criticality-alarm/shielding benchmarks and fundamental physics measurements have been included in the database. There were 12 countries participating on the ICSBEP in 2003. That number has increased to 18 with recent contributions of data and/or resources from Brazil, Czech Republic, Poland, India, Canada, and China. South Africa, Germany, Argentina, and Australia have been invited to participate. Since ICNC 2003, the contents of the ''International Handbook of Evaluated Criticality Safety Benchmark Experiments'' have increased from 350 evaluations (28,000 pages) containing benchmark specifications for 3070 critical or subcritical configurations to 442 evaluations (over 38,000 pages) containing benchmark specifications for 3957 critical or subcritical configurations, 23 criticality-alarm-placement/shielding configurations with multiple dose points for each, and 20 configurations that have been categorized as fundamental physics measurements that are relevant to criticality safety applications in the 2006 Edition of the ICSBEP Handbook. Approximately 30 new evaluations and 250 additional configurations are expected to be added to the 2007 Edition of the Handbook. Since ICNC 2003, a reactor physics counterpart to the ICSBEP, The International Reactor Physics Experiment Evaluation Project (IRPhEP) was initiated. Beginning in 1999, the IRPhEP was conducted as a pilot activity by the by the Organization of Economic Cooperation and Development (OECD) Nuclear Energy Agency

Modelling of 28-element UO2 flux-map critical experiments in ZED-2 using WIMS9A/PANTHER

International Nuclear Information System (INIS)

Sissaoui, M.T.; Kozier, K.S.; Labrie, J.P.

2011-01-01

The accuracy of WIMS9A/PANTHER in modelling D 2 O-moderated, and H 2 O- or air-cooled, doubly heterogeneous lattices of fuel clusters has been demonstrated using 28-element UO 2 flux-map critical experiments in the ZED-2 facility. Presented here are the predicted k eff values, coolant void reactivity biases, and the radial and axial flux shapes.

ANL results for LMFR reactivity coefficients benchmark

International Nuclear Information System (INIS)

Hill, Robert

2000-01-01

The fast reactor analysis methods developed at ANL were extensively tested in ZPR and ZPPR experiments, applied to EBR-2 and FFTF test reactors. The basic nuclear data library used was ENDF/B-V.2 with the ETOE-2 data processing code and the ENDF/B-VI. Multigroup constants were generated by Monte Carlo code MCNP 2 -2. Neutron flux calculation were done by DIF3D code applying neutron diffusion theory and finite difference method. The results obtained include basic parameters; fuel and structure regional Doppler coefficients; geometry expansion fuel coefficients; kinetics parameters. In general, agreement between phase 1 and 2 results were excellent

Critical superheats upon boiling of dissociating liquids

International Nuclear Information System (INIS)

Kolykhan, L.I.; Solov'ev, V.N.

1985-01-01

The experimental data on critical superheats of dissociating liquids, i.e. nitrogen tetroxide and nitrine are presented (nitrine is the solution of nitrogen oxide in nitrogen tetroxide). The experiments with boiling N 2 O 4 have been carried out in the pressure range 0.1-3.0 MPa and with boiling nitrine within the pressure range 0.2-9.0 MPa. The experiments have revealed an anomalous dependence of critical superheats on pressure P, thus at P>=2.5 MPa the critical superheat values exceed the limiting ones, and at P=4.5 MPa this excess amounts to more than 16 K, essentially exceeding the errors of the experiments. The results for N 2 O 4 critical superheats agree with experimental data of other authors. Complex phenomena observed upon boiling of dissociating liquids require further theoretical and experimental studies

Intensive care survivors' experiences of ward-based care: Meleis' theory of nursing transitions and role development among critical care outreach services.

Science.gov (United States)

Ramsay, Pam; Huby, Guro; Thompson, Andrew; Walsh, Tim

2014-03-01

To explore the psychosocial needs of patients discharged from intensive care, the extent to which they are captured using existing theory on transitions in care and the potential role development of critical care outreach, follow-up and liaison services. Intensive care patients are at an increased risk of adverse events, deterioration or death following ward transfer. Nurse-led critical care outreach, follow-up or liaison services have been adopted internationally to prevent these potentially avoidable sequelae. The need to provide patients with psychosocial support during the transition to ward-based care has also been identified, but the evidence base for role development is currently limited. Twenty participants were invited to discuss their experiences of ward-based care as part of a broader study on recovery following prolonged critical illness. Psychosocial distress was a prominent feature of their accounts, prompting secondary data analysis using Meleis et al.'s mid-range theory on experiencing transitions. Participants described a sense of disconnection in relation to profound debilitation and dependency and were often distressed by a perceived lack of understanding, indifference or insensitivity among ward staff to their basic care needs. Negotiating the transition between dependence and independence was identified as a significant source of distress following ward transfer. Participants varied in the extent to which they were able to express their needs and negotiate recovery within professionally mediated boundaries. These data provide new insights into the putative origins of the psychosocial distress that patients experience following ward transfer. Meleis et al.'s work has resonance in terms of explicating intensive care patients' experiences of psychosocial distress throughout the transition to general ward-based care, such that the future role development of critical care outreach, follow-up and liaison services may be more theoretically informed

Contributions at the Tripoli Monte Carlo code qualifying on critical experiences and at neutronic interaction study of fissile units

International Nuclear Information System (INIS)

Nouri, A.

1994-01-01

Criticality studies in nuclear fuel cycle are based on Monte Carlo method. These codes use multigroup cross sections which can verify by experimental configurations or by use of reference codes such Tripoli 2. In this Tripoli 2 code nuclear data are errors attached and asked for experimental studies with critical experiences. This is one of the aim of this thesis. To calculate the keff of interacted fissile units we have used the multigroup Monte Carlo code Moret with convergence problems. A new estimator of reactions rates permit to better approximate the neutrons exchange between units and a new importance function has been tested. 2 annexes

Analysis of MOZART critical experiment using the IRPhEP handbook data

International Nuclear Information System (INIS)

Chiba, Go

2010-12-01

Using the experimental data described in the IRPhEP handbook, an experimental analysis of the MOZART experiment is carried out with the nuclear data JENDL-4.0, and the reactor physics codes SLAROM-UF and CBG. The following results are obtained: -The C/E values for criticality are 0.9981 for the small-sized core MZA and 1.0006 for the middle-sized core MZB. Good agreement between calculation and experimental values has been observed similarly in the analyses for criticality of other MOX-fueled fast reactors. Hence, consistency between the present analysis and the others is confirmed. -In reaction rate ratios at the core center, calculation values agree with experimental values within 1.0% for F25/F49 and C28/F49, and within 4.0% for F28/F25, F40/F49 and F41/F49. -In sodium void reactivity worths, calculation values are about 10% larger than experimental values for the non-leakage-dominated data. For the data to which the leakage component largely contributes, absolute differences normalized by the leakage component are less than 10%. -In material worths, calculation values are about 5% larger than experimental values for plutonium. Calculation values agree with experimental values within 10% differences for uranium and SS. -In control rod worths, calculation values are 2% to 5% larger than experimental values. -In reaction rate distributions, calculation values agree well with experimental values in core regions. On the other hand, underestimation is observed systematically in calculation values of threshold reactions in blanket regions. For the reactivity characteristic, overestimation is systematically observed in calculations. While the reason has not yet been investigated, the result suggests underestimation of β eff . (author)

Effects of neutron data libraries and criticality codes on IAEA criticality benchmark problems

International Nuclear Information System (INIS)

Sarker, Md.M.; Takano, Makoto; Masukawa, Fumihiro; Naito, Yoshitaka

1993-10-01

In order to compare the effects of neutron data libraries and criticality codes to thermal reactors (LWR), the IAEA criticality benchmark calculations have been performed. The experiments selected in this study include TRX-1 and TRX-2 with a simple geometric configuration. Reactor lattice calculation codes WIMS-D/4, MCNP-4, JACS (MGCL, KENO), and SRAC were used in the present calculations. The TRX cores were analyzed by WIMS-D/4 using WIMS original library and also by MCNP-4, JACS (MGCL, KENO), and SRAC using the libraries generated from JENDL-3 and ENDF/B-IV nuclear data files. An intercomparison work for the above mentioned code systems and cross section libraries was performed by analyzing the LWR benchmark experiments TRX-1 and TRX-2. The TRX cores were also analyzed for supercritical and subcritical conditions and these results were compared. In the case of critical condition, the results were in good agreement. But for the supercritical and subcritical conditions, the difference of the results obtained by using the different cross section libraries become larger than for the critical condition. (author)

High-Temperature Gas-Cooled Reactor Critical Experiment and its Application to Thorium Absorption Rates

International Nuclear Information System (INIS)

Bardes, R.G.; Brown, J.R.; Drake, M.K.; Fischer, P.U.; Pound, D.C.; Sampson, J.B.; Stewart, H.B.

1964-01-01

In developing the concept of the HTGR and its first prototype at Peach Bottom, General Atomic made the decision that a critical experiment was required to provide adequately certain necessary input data for the nuclear analysis. The specific needs of the nuclear design theory for input data relating to thorium absorptions led to an experimental design consisting of a central lattice-type critical assembly with surrounding buffer and driver regions. This type of assembly, in which the spectrum of interest can be established in the relatively small central lattice having a desired geometry, provides a useful tool for obtaining a variety of input data for nuclear analysis surveys of new concepts. The particular advantages of this approach over that of constructing a mock-up assembly will be discussed, as well as the role of the theory in determining what experiments are most useful and how these experiments are then used in verifying design techniques. Two relatively new techniques were developed for use in the lattice assembly. These were a reactivity oscillation technique for determining the thorium Doppler coefficient, and an activation technique for determining both the resonance integral of thorium dispersed in graphite and its temperature dependence (activation Doppler coefficient). The Doppler coefficient measurement by reactivity oscillation utilized the entire central fuel element in a technique which permitted heating this fuel element to 800°F and accurately subtracting experimentally the thermal-base effects, that is, those effects not contributing to the thorium resonance capture. Comparison of results with theory for a range of conditions shows excellent agreement. The measurement of the thorium resonance integral and its temperature dependence will be described. The technique developed for measuring resonance capture makes use of gold as the standard and vanadium as die material giving the 1/v absorption rate. This technique is dictated by the fact

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...

Critical scattering of neutrons by Fe: study of the hydrodynamic and critical regions

International Nuclear Information System (INIS)

Parette, Georges

1971-01-01

In the present work we describe the latest experiments on the critical magnetic scattering of neutrons by iron just above the Curie temperature, performed at the Centre d'Etudes Nucleaires at Saclay. In these experiments we have tried to explore the 'hydrodynamical region' as defined by the 'scaling laws' and to determine the temperature dependence of the diffusion constant. These experiments yield a verification of the recent theoretical calculations made by P. Resibois and C. Piette. These calculations and several measurements which we have conducted show the existence of an intermediate region between the 'critical' and the 'hydrodynamical' regions, which we call the 'quasi-hydrodynamical' region. In the hydrodynamical region, whose borders are well defined by the calculations of Resibois and Piette, our results confirm the theoretical predictions concerning this region. (author) [fr

Analysis of the IPEN/MB-01 critical unit based on criticality experiments

International Nuclear Information System (INIS)

Santos, Adimir dos; Yamaguchi, Mitsuo; Ferreira, Carlos Roberto; Yoriyaz, Helio

1995-01-01

The analysis of the critical loading of the IPEN/MB-01 was performed by using several reactor cell methodologies. The results obtained by using the coupled NJOY/AMPX-II/HAMMER-TECHNION shows the good quality of the available nuclear data files as well as the methodologies in the Reactor Physics area. The original HAMMER system shows results that are well as the methodologies in the Reactor Physics area. The original HAMMER system shows results that are well outside of the desired quality for a cell code. (author), 15 refs, 3 figs, 5 tabs

Re-mastering the Master's Tools: Recognizing and affirming the life experiences and cultural practices of urban youth in critical computational literacy through a video game project

OpenAIRE

Lee, Clifford

2012-01-01

This study examines how a video game project that focuses on students' lived experiences and cultural practices teach critical literacies and computational thinking. Specifically, this research looked at how the pedagogy, processes, and student products demonstrated culturally relevant pedagogy practices, critical literacy, and computational thinking. This design-based research study utilizes critical literacy, sociocultural learning theory, and culturally relevant pedagogy in the framing, st...

Operating procedures for the Pajarito Site Critical Assembly Facility

International Nuclear Information System (INIS)

Malenfant, R.E.

1983-03-01

Operating procedures consistent with DOE Order 5480.2, Chapter VI, and the American National Standard Safety Guide for the Performance of Critical Experiments are defined for the Pajarito Site Critical Assembly Facility of the Los Alamos National Laboratory. These operating procedures supersede and update those previously published in 1973 and apply to any criticality experiment performed at the facility

Handling of time-critical Conditions Data in the CMS experiment - Experience of the first year of data taking

CERN Multimedia

CERN. Geneva

2012-01-01

Data management for a wide category of non-event data plays a critical role in the operation of the CMS experiment. The processing chain (data taking-reconstruction-analysis) relies in the prompt availability of specific, time dependent data describing the state of the various detectors and their calibration parameters, which are treated separately from event data. The Condition Database system is the infrastructure established to handle these data and to make sure that they are available to both offline and online workflows. The Condition Data layout is designed such that the payload data (the Condition) is associated to an Interval Of Validity (IOV). The IOV allows accessing selectively the sets corresponding to specific intervals of time, run number or luminosity section. Both payloads and IOVs are stored in a cluster of relational database servers (Oracle) using an object-relational access approach. The strict requirements of security and isolation of the CMS online systems are imposing a redundant archit...

Critical experiments supporting underwater storage of tightly packed configurations of spent fuel pins. Technical progress report, January 1-March 31, 1981

International Nuclear Information System (INIS)

Hoovler, G.S.; Baldwin, M.N.

1981-04-01

Critical experiments are in progress on arrays of 2 1/2% enriched UO 2 fuel pins simulating underwater pin storage of spent power reactor fuel. Pin storage refers to a spent fuel storage concept in which the fuel assemblies are dismantled and the fuel pins are tightly packed into specially designed canisters. These experiments are providing benchmark data with which to validate nuclear codes used to design spent fuel pin storage racks

[REPORTING CRITICAL LAB RESULTS, A CHALLENGE FOR THE LAB AND THE PHYSICIAN - A SUMMARY OF FOUR YEARS OF EXPERIENCE IN MEIR MEDICAL CENTER LABORATORIES].

Science.gov (United States)

Rashid, Gloria; Goldman, Jacob; Weinstein, Doron; Tohami, Tali; Neumark, Eran; Weiss, Eli

2015-08-01

Critical laboratory results require prompt reporting to the attending physician, as they may indicate that a patient is in a life-threatening condition. Although this important subject has been covered in many publications, it needs more attention from our healthcare organizations, which have no official policy on the subject. Matching expectations between the doctor and the laboratory needs to be better defined. The aim of this work was to inform the community of doctors and laboratories about the multiple problems concerning the reporting of critical laboratory results, to create a platform for exchanging views and ideas, and to build an extensive infrastructure for developing a unified plan to address this important issue. We present the results of four years of experience of reporting critical laboratory values at the Meir Medical Center Laboratories. The idea leading this work was to present the relatively low rate of critical results reported by the laboratories in 2010, sharing the problems discovered while investigating the situation in depth, and presenting the solutions that enabled us to obtain the desired results within four years. Gradual implementation of these improvements resulted in critical value reporting increasing from 55% in 2010 to 95% currently. We suggest a model for improving critical laboratory values reporting based on our 4-year experience, which emphasizes: (1) The importance of selecting proper tests and values for critical results; (2) The significance of using technology and computerized measures to support the process; and (3) Developing quick procedures for monitoring and controlling the process.

Preparation of a criticality benchmark based on experiments performed at the RA-6 reactor

International Nuclear Information System (INIS)

Bazzana, S.; Blaumann, H; Marquez Damian, J.I

2009-01-01

The operation and fuel management of a reactor uses neutronic modeling to predict its behavior in operational and accidental conditions. This modeling uses computational tools and nuclear data that must be contrasted against benchmark experiments to ensure its accuracy. These benchmarks have to be simple enough to be possible to model with the desired computer code and have quantified and bound uncertainties. The start-up of the RA-6 reactor, final stage of the conversion and renewal project, allowed us to obtain experimental results with fresh fuel. In this condition the material composition of the fuel elements is precisely known, which contributes to a more precise modeling of the critical condition. These experimental results are useful to evaluate the precision of the models used to design the core, based on U 3 Si 2 and cadmium wires as burnable poisons, for which no data was previously available. The analysis of this information can be used to validate models for the analysis of similar configurations, which is necessary to follow the operational history of the reactor and perform fuel management. The analysis of the results and the generation of the model were done following the methodology established by International Criticality Safety Benchmark Evaluation Project, which gathers and analyzes experimental data for critical systems. The results were very satisfactory resulting on a value for the multiplication factor of the model of 1.0000 ± 0.0044, and a calculated value of 0.9980 ± 0.0001 using MCNP 5 and ENDF/B-VI. The utilization of as-built dimensions and compositions, and the sensitivity analysis allowed us to review the design calculations and analyze their precision, accuracy and error compensation. [es

Working together: critical care nurses experiences of temporary staffing within Swedish health care: A qualitative study.

Science.gov (United States)

Berg Jansson, Anna; Engström, Åsa

2017-08-01

The aim of this study is to describe critical care nurses (CCN's) experiences of working with or as temporary agency staff. This explorative qualitative study is based on interviews with five agency CCNs and five regular CCNs, a total of ten interviews, focusing on the interviewees' experiences of daily work and temporary agency staffing. The interviews were analysed manually and thematically following an inductive approach. Four themes that illustrate both similarities and differences between regular and temporary agency CCNs emerged: "working close to patients versus being responsible for everything", "teamwork versus independence", "both groups needed" and "opportunities and challenges". The study findings illustrate the complexity of the working situation for agency and regular staff in terms of the organisation and management of the temporary agency nurses and the opportunities and challenges faced by both groups. Copyright © 2016 Elsevier Ltd. All rights reserved.

Developing Critical Thinking through Leadership Education

Science.gov (United States)

Jenkins, Daniel M.; Andenoro, Anthony C.

2016-01-01

This chapter provides the critical leadership logic model as a tool to help educators develop leadership-learning opportunities. This proactive logic model includes curricular and co-curricular educational experiences to ensure critical thinking through leadership education.

Criticality experiments: analysis, evaluation, and programs. 8. Prompt Neutron Decay Constants in Uranium Diluted with Matrix Material Systems

International Nuclear Information System (INIS)

Sanchez, Rene; Loaiza, David; Brunson, Glenn

2001-01-01

Rossi-Alpha measurements were performed on uranium diluted with matrix material systems to determine the prompt neutron decay constants. These constants represent an eigenvalue characteristic of these particular critical assemblies, which can be experimentally measured by the Rossi-Alpha or pulse neutron source techniques and calculated by a deterministic or Monte Carlo method. In the measurements presented in this paper, highly enriched foils diluted in various X/ 235 U ratios with polyethylene and SiO 2 , and polyethylene and aluminum were assembled to a high multiplication, and the prompt neutron decay constants were obtained by the Rossi-Alpha technique. The uranium diluted with matrix material experiments were fueled with highly enriched uranium foils. The average dimensions of the bare foils were 22.86 cm squared and 0.00762 cm thick. The foils were laminated with plastic sheets to reduce the amount of airborne contamination. Each foil weighed ∼70 g. The diluent material consisted of SiO 2 , or 6061 aluminum plates, which were embedded into polyethylene plates. The SiO 2 and aluminum plates were 22.86 cm square and 0.64 cm thick. The polyethylene plates were 39.12 cm square and 1.91 cm thick. Each polyethylene plate had a central recess whose dimensions were 22.86 cm by 22.86 cm by 0.64 cm deep and was used to accommodate the SiO 2 , or aluminum plates as well as the uranium foils. There were eight 39.12-cm-squared by 2.54-cm-thick high density polyethylene plates that form the top and bottom reflectors (four at the top and four at the bottom). Also, one of the polyethylene plates located in the center of the assembly had holes drilled in a radial direction to accommodate neutron detectors. Four 3 He detectors were placed in this plate. The 3 He detectors were 1.27 cm in diameter and ∼15 cm long. Rossi-Alpha measurements were performed at several subcritical separations for both experiments. The data were collected with a type I time analyzer (PATRM

Clinical Experiences and Mediational Activities in Urban Teacher Preparation: Learning and Critical Consciousness

Directory of Open Access Journals (Sweden)

Craig Willey

2016-11-01

Full Text Available In a longitudinal design experiment conducted within an urban teacher preparation program, we employed ethnographic and auto-ethnographic methods to investigate the following questions: 1 In what ways do clinical experiences (CEs support prospective teachers’ (PTs development of knowledge, skills, and dispositions necessary for urban teaching? 2 How is it determined that adjustments need to be made to the design and facilitation of CEs, and what did these adjustments yield in terms of student learning outcomes? The program centers and leverages CEs in order for PTs to connect theory and practice, particularly an awareness of, and skills associated with, equitable teaching practices. In our two-year field-based program, CEs included community explorations, one-on-one and small group work with children, two student teaching practicums, and various school-community events. We describe the process undertaken to maximize the benefits yielded from CEs. After working with three cohorts of PTs for their entire professional training, we found that: 1 focusing attention on the intentional design and assessment of the mediational activities coupled with CEs leads to more nuanced understandings and enactments of culturally relevant teaching among PTs; and 2 CEs afford PTs abundant opportunities to shape complex identities as urban teachers. Specifically, we found that clinical experiences and corresponding mediational activities support PTs’ understanding of families of color, allow them to recognize and address problematic schooling practices, and strengthen PTs’ otherwise fragile critical consciousness. We conclude that strategic interventions can provide clarity for PTs around what has been learned, and what is left to be developed

Critical care nurses' experiences of performing successful peripheral intravenous catheterization in difficult situations.

Science.gov (United States)

Forsberg, Angelica; Engström, Åsa

2018-06-01

The aim of this study is to describe the experiences of critical care nurses (CCNs) when performing successful peripheral intravenous catheterization (PIVC) on adult inpatients in difficult situations. This study uses a descriptive design with a qualitative approach. Semistructured interviews were given to CCNs (n = 22) at a general central county hospital in northern Sweden. The interview text was analyzed with qualitative thematic content analysis. Three themes emerged: "releasing time and creating peace," "feeling self-confidence in the role of expert nurse," and "technical interventions promoting success." CCNs stated that apart from experience, releasing enough time is the most crucial factor for a successful PIVC. They emphasized the importance of identifying the kinds of difficulties that may occur during the procedure, for example, fragile or/and invisible veins. CCNs explained that compared to when they were newly graduated, the difference in their approach nowadays has changed to using their hands more than their eyes and that they feel comfortable with bodily palpations. To further optimize PIVC performing skills, continued possibilities to train and learn in hospital settings are necessary, even after formal education has been completed. Copyright © 2018 Society for Vascular Nursing, Inc. Published by Elsevier Inc. All rights reserved.

Criticality safety (prospect of study in NUCEF)

International Nuclear Information System (INIS)

Itagaki, Masafumi

1996-01-01

Experimental studies of criticality safety are under way using STACY and TRACY in NUCEF. Collection of fundamental data on criticality in a solution system is undergoing with STACY to confirm that the likelihood of criticality safety in the system constructed on the assumption of apparatuses in a reprocessing plant is enough large. Whereas some experiments simulating criticality accidents in a reprocessing plant using TRACY were designed to investigate the behaviors of fuel solution and radioactive matters in order to clarify whether it is possible to safely shut them in the facility even if a critical accident occurs. Both STACY and TRACY reached the criticality in 1995. Up to now a series of criticality experiments have been done using STACY with a core tank φ60 cm and the first periodical examination is now under way. On the other hand, we have a plan using TRACY to investigate the behaviors of nuclear heat solution at a criticality accident, and the releasing, transfer and deposition of radioactive materials. After reaching the criticality for the first, the performance verification test has been conducted. The full-scale study using TRACY is planned to begin in the second half of 1996. (M.N.)

Magnetic field-aligned plasma expansion in critical ionization velocity space experiments

International Nuclear Information System (INIS)

Singh, N.

1989-01-01

Motivated by the recent Critical Ionization Velocity (CIV) experiments in space, the temporal evolution of a plasma cloud released in an ambient plasma is studied. Time-dependent Vlasov equations for both electrons and ions, along with the Poisson equation for the self-consistent electric field parallel to the ambient magnetic field, are solved. The initial cloud is assumed to consist of cold, warm, and hot electrons with temperatures T/sub c/ ≅ 0.2 eV, T/sub w/ ≅ 2 eV, and T/sub h/ ≅ 10 eV, respectively. It is found that the minor hot electrons escape the cloud, and their velocity distribution function shows the typical time-of-flight dispersion feature - that is, the larger the distance from the cloud, the larger is the average drift velocity of the escaping electrons. The major warm electrons expand along the magnetic field line with the corresponding ion-acoustic speed. The combined effect of the escaping hot electrons and the expanding warm ones sets up an electric potential structure which accelerates the ambient electrons into the cloud. Thus, the energy loss due to the electron escape is partly replenished. The electric field distribution in the potential structure depends on the stage of the evolution; before the rarefaction waves propagating from the edges of the cloud reach its center, the electric fields point into the cloud. After this stage the cloud divides into two subclouds, with each having their own bipolar electric fields. Effects of collisions on the evolution of plasma clouds are also discussed. The relevance of the results seen from the calculations are discussed in the context of recent space experiments on CIV

Theoretical Perspectives on Critical Thinking Teaching: Reflections from Field Experiences from a Norwegian Lower Secondary School in Comparison to Tanzanian Secondary School Teaching Practices

Directory of Open Access Journals (Sweden)

Leatitia Gabriel Mashaza

2017-08-01

Full Text Available This paper presents the theoretical perspectives relevant to critical thinking as my topic of research during my teaching practice period which was conducted from 12th -28th October 2015 at Eidsvag secondary school in Bergen, Norway. As a requirement for Masters’ degree in social science education, all master students were required to engage in teaching practice in different Norwegian primary and secondary schools. Importantly, every student teacher was given a topic of concentration as a mini-research for the whole teaching practice period. My topic of research focused at exploring and gaining the theoretical and practical perspectives on critical thinking teaching by drawing some experiences from a Norwegian lower secondary school (Eidsvag skole in reflection to secondary school teaching practice experiences in Tanzania. Therefore, in this paper, my reflections with regard to the conditions favoring the possibility for critical thinking teaching and how it was enhanced by teachers at my practice school will be discussed. Further to that, I will also present the observed challenges of which, in my view, in way or another intervened the possibility for effective critical thinking teaching to take place.

ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

Energy Technology Data Exchange (ETDEWEB)

Kahler, A. [Los Alamos National Laboratory (LANL); Macfarlane, R E [Los Alamos National Laboratory (LANL); Mosteller, R D [Los Alamos National Laboratory (LANL); Kiedrowski, B C [Los Alamos National Laboratory (LANL); Frankle, S C [Los Alamos National Laboratory (LANL); Chadwick, M. B. [Los Alamos National Laboratory (LANL); Mcknight, R D [Argonne National Laboratory (ANL); Lell, R M [Argonne National Laboratory (ANL); Palmiotti, G [Idaho National Laboratory (INL); Hiruta, h [Idaho National Laboratory (INL); Herman, Micheal W [Brookhaven National Laboratory (BNL); Arcilla, r [Brookhaven National Laboratory (BNL); Mughabghab, S F [Brookhaven National Laboratory (BNL); Sublet, J C [Culham Science Center, Abington, UK; Trkov, A. [Jozef Stefan Institute, Slovenia; Trumbull, T H [Knolls Atomic Power Laboratory; Dunn, Michael E [ORNL

2011-01-01

The ENDF/B-VII.1 library is the latest revision to the United States' Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [1]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unrnoderated and uranium reflected (235)U and (239)Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected actinide reaction rates such as (236)U; (238,242)Pu and (241,243)Am capture in fast systems. Other deficiencies, such as the overprediction of Pu solution system critical

Falsification of matching theory and confirmation of an evolutionary theory of behavior dynamics in a critical experiment.

Science.gov (United States)

McDowell, J J; Calvin, Olivia L; Hackett, Ryan; Klapes, Bryan

2017-07-01

Two competing predictions of matching theory and an evolutionary theory of behavior dynamics, and one additional prediction of the evolutionary theory, were tested in a critical experiment in which human participants worked on concurrent schedules for money (Dallery et al., 2005). The three predictions concerned the descriptive adequacy of matching theory equations, and of equations describing emergent equilibria of the evolutionary theory. Tests of the predictions falsified matching theory and supported the evolutionary theory. Copyright © 2017 Elsevier B.V. All rights reserved.

Příspěvek k poznání petrografie, mineralogie a fluidních inkluzí jeskynních sintrů první generace z Koněpruských jeskyní a z některých lokalit v jejich okolí

Czech Academy of Sciences Publication Activity Database

Suchý, V.; Dobeš, P.; Zeman, Antonín

2014-01-01

Roč. 47, č. 1 (2014), s. 140-143 ISSN 0514-8057 Institutional support: RVO:68378297 Keywords : Bohemian Karst * speleothems * aragonite * gothic -arch calcite * fluid inclusions Subject RIV: AL - Art, Architecture, Cultural Heritage http://www.geology.cz/img/zpravyvyzkum/fulltext/Zpr2013D-11.pdf

Holocenní souvrství pod Skalou Posledného komína v Zádielské tiesňavě (NP Slovenský kras)

Czech Academy of Sciences Publication Activity Database

Ložek, Vojen; Cílek, Václav

2014-01-01

Roč. 2013, č. 1 (2014), s. 160-164 ISSN 0514-8057 Institutional support: RVO:67985831 Keywords : Holocene * rock-face talus * foam sinter * molluscan succession * Slovak Karst * Slovakia Subject RIV: DB - Geology ; Mineralogy http://www.geology.cz/zpravy/obsah/2013/Zpr2013F-2.pdf

Review of the CRAC and SILENE Criticality Accident Studies

International Nuclear Information System (INIS)

Barbry, F.; Fouillaud, P.; Grivot, P.; Reverdy, L.

2009-01-01

In 1967, the Commissariat et l'Energie Atomique (French Atomic Energy Agency) performed its first research on criticality accidents for the purpose of limiting their impact on people, the environment, and nuclear facilities themselves. A criticality accident is accompanied by intense neutron and gamma emissions and release of radioactive fission products-gases and aerosols-gene rating risk of irradiation and contamination. This work has supplemented earlier work in criticality safety, which concentrated on critical mass measurements and computations. Understanding of the consequences of criticality accidents was limited. Emergency planning was hampered by lack of data. Information became available from pulsed reactor experiments, but the experiments were restricted to the established reactor configurations. The objectives of research performed at the Valduc criticality laboratory, mainly on aqueous fissile media, using the CRAC and SILENE facilities, by multidisciplinary teams of physicists, dosimetry specialists, and radio-biologists, were to model criticality accident physics, estimate irradiation risks and radioactive releases, detect excursions, and organize emergency response. The results of the Valduc experiments have contributed toward improved understanding of criticality accident phenomenology and better evaluation of the risks associated with such accidents. (authors)

Review of the CRAC and SILENE Criticality Accident Studies

Energy Technology Data Exchange (ETDEWEB)

Barbry, F.; Fouillaud, P.; Grivot, P.; Reverdy, L. [CEA Valduc, Serv Rech Neutron and Critcite, 21 - Is-sur-Tille (France)

2009-02-15

In 1967, the Commissariat et l'Energie Atomique (French Atomic Energy Agency) performed its first research on criticality accidents for the purpose of limiting their impact on people, the environment, and nuclear facilities themselves. A criticality accident is accompanied by intense neutron and gamma emissions and release of radioactive fission products-gases and aerosols-gene rating risk of irradiation and contamination. This work has supplemented earlier work in criticality safety, which concentrated on critical mass measurements and computations. Understanding of the consequences of criticality accidents was limited. Emergency planning was hampered by lack of data. Information became available from pulsed reactor experiments, but the experiments were restricted to the established reactor configurations. The objectives of research performed at the Valduc criticality laboratory, mainly on aqueous fissile media, using the CRAC and SILENE facilities, by multidisciplinary teams of physicists, dosimetry specialists, and radio-biologists, were to model criticality accident physics, estimate irradiation risks and radioactive releases, detect excursions, and organize emergency response. The results of the Valduc experiments have contributed toward improved understanding of criticality accident phenomenology and better evaluation of the risks associated with such accidents. (authors)

Enhancing Critical Thinking across the Undergraduate Experience: An Exemplar from Engineering

Science.gov (United States)

Ralston, Patricia A.; Bays, Cathy L.

2013-01-01

Faculty in a large, urban school of engineering designed a longitudinal study to assess the critical thinking skills of undergraduate students as they progressed through the engineering program. The Paul-Elder critical thinking framework was used to design course assignments and develop a holistic assessment rubric. The curriculum was re-designed…

Nuclear criticality safety: 2-day training course

International Nuclear Information System (INIS)

Schlesser, J.A.

1992-11-01

This compilation of notes is presented as a source reference for the criticality safety course. At the completion of this training course, the attendee will: (1) be able to define terms commonly used in nuclear criticality safety; (2) be able to appreciate the fundamentals of nuclear criticality safety; (3) be able to identify factors which affect nuclear criticality safety; (4) be able to identify examples of criticality controls as used at Los Alamos; (5) be able to identify examples of circumstances present during criticality accidents; (6) have participated in conducting two critical experiments

Quantum critical dynamics for a prototype class of insulating antiferromagnets

Science.gov (United States)

Wu, Jianda; Yang, Wang; Wu, Congjun; Si, Qimiao

2018-06-01

Quantum criticality is a fundamental organizing principle for studying strongly correlated systems. Nevertheless, understanding quantum critical dynamics at nonzero temperatures is a major challenge of condensed-matter physics due to the intricate interplay between quantum and thermal fluctuations. The recent experiments with the quantum spin dimer material TlCuCl3 provide an unprecedented opportunity to test the theories of quantum criticality. We investigate the nonzero-temperature quantum critical spin dynamics by employing an effective O (N ) field theory. The on-shell mass and the damping rate of quantum critical spin excitations as functions of temperature are calculated based on the renormalized coupling strength and are in excellent agreement with experiment observations. Their T lnT dependence is predicted to be dominant at very low temperatures, which will be tested in future experiments. Our work provides confidence that quantum criticality as a theoretical framework, which is being considered in so many different contexts of condensed-matter physics and beyond, is indeed grounded in materials and experiments accurately. It is also expected to motivate further experimental investigations on the applicability of the field theory to related quantum critical systems.

Nuclear criticality safety: 2-day training course

International Nuclear Information System (INIS)

Schlesser, J.A.

1997-02-01

This compilation of notes is presented as a source reference for the criticality safety course. At the completion of this training course, the attendee will: be able to define terms commonly used in nuclear criticality safety; be able to appreciate the fundamentals of nuclear criticality safety; be able to identify factors which affect nuclear criticality safety; be able to identify examples of criticality controls as used as Los Alamos; be able to identify examples of circumstances present during criticality accidents; have participated in conducting two critical experiments; be asked to complete a critique of the nuclear criticality safety training course

Nuclear criticality safety: 2-day training course

Energy Technology Data Exchange (ETDEWEB)

Schlesser, J.A. [ed.] [comp.

1997-02-01

This compilation of notes is presented as a source reference for the criticality safety course. At the completion of this training course, the attendee will: be able to define terms commonly used in nuclear criticality safety; be able to appreciate the fundamentals of nuclear criticality safety; be able to identify factors which affect nuclear criticality safety; be able to identify examples of criticality controls as used as Los Alamos; be able to identify examples of circumstances present during criticality accidents; have participated in conducting two critical experiments; be asked to complete a critique of the nuclear criticality safety training course.

Writing Critical Race Theory and Method: A Composite Counterstory on the Experiences of Black Teachers in New Orleans Post-Katrina

Science.gov (United States)

Cook, Daniella Ann; Dixson, Adrienne D.

2013-01-01

Using a critical race theory lens, the authors propose a way of writing race research using composite counterstories. Drawing on data from a yearlong study of school rebuilding in the time period immediately after Hurricane Katrina devastated the City of New Orleans, the authors examine the experiences of African-American educators in the school…

Ontario Hydro experience in the identification and mitigation of potential failures in safety critical software systems

International Nuclear Information System (INIS)

Huget, R.G.; Viola, M.; Froebel, P.A.

1995-01-01

Ontario Hydro has had experience in designing and qualifying safety critical software used in the reactor shutdown systems of its nuclear generating stations. During software design, an analysis of system level hazards and potential hardware failure effects provide input to determining what safeguards will be needed. One form of safeguard, called software self checks, continually monitor the health of the computer on line. The design of self checks usually is a trade off between the amount of computing resources required, the software complexity, and the level of safeguarding provided. As part of the software verification activity, a software hazards analysis is performed, which identifiers any failure modes that could lead to the software causing an unsafe state, and which recommends changes to mitigate that potential. These recommendations may involve a re-structuring of the software to be more resistant to failure, or the introduction of other safeguarding measures. This paper discusses how Ontario Hydro has implemented these aspects of software design and verification into safety critical software used in reactor shutdown systems

The Development, Content, Design, and Conduct of the 2011 Piloted US DOE Nuclear Criticality Safety Program Criticality Safety Engineering Training and Education Project

International Nuclear Information System (INIS)

Hopper, Calvin Mitchell

2011-01-01

In May 1973 the University of New Mexico conducted the first nationwide criticality safety training and education week-long short course for nuclear criticality safety engineers. Subsequent to that course, the Los Alamos Critical Experiments Facility (LACEF) developed very successful 'hands-on' subcritical and critical training programs for operators, supervisors, and engineering staff. Since the inception of the US Department of Energy (DOE) Nuclear Criticality Technology and Safety Project (NCT and SP) in 1983, the DOE has stimulated contractor facilities and laboratories to collaborate in the furthering of nuclear criticality as a discipline. That effort included the education and training of nuclear criticality safety engineers (NCSEs). In 1985 a textbook was written that established a path toward formalizing education and training for NCSEs. Though the NCT and SP went through a brief hiatus from 1990 to 1992, other DOE-supported programs were evolving to the benefit of NCSE training and education. In 1993 the DOE established a Nuclear Criticality Safety Program (NCSP) and undertook a comprehensive development effort to expand the extant LACEF 'hands-on' course specifically for the education and training of NCSEs. That successful education and training was interrupted in 2006 for the closing of the LACEF and the accompanying movement of materials and critical experiment machines to the Nevada Test Site. Prior to that closing, the Lawrence Livermore National Laboratory (LLNL) was commissioned by the US DOE NCSP to establish an independent hands-on NCSE subcritical education and training course. The course provided an interim transition for the establishment of a reinvigorated and expanded two-week NCSE education and training program in 2011. The 2011 piloted two-week course was coordinated by the Oak Ridge National Laboratory (ORNL) and jointly conducted by the Los Alamos National Laboratory (LANL) classroom education and facility training, the Sandia National

International Criticality Safety Benchmark Evaluation Project (ICSBEP) - ICSBEP 2015 Handbook

International Nuclear Information System (INIS)

Bess, John D.

2015-01-01

The Criticality Safety Benchmark Evaluation Project (CSBEP) was initiated in October of 1992 by the United States Department of Energy (DOE). 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 Nuclear Energy Agency (NEA) in 1995. This handbook contains criticality safety benchmark specifications that have been derived from experiments performed at various critical facilities around the world. The benchmark specifications are intended for use by criticality safety engineers to validate calculation techniques used to establish minimum subcritical margins for operations with fissile material and to determine criticality alarm requirements 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 approximately 69000 pages and contain 567 evaluations with benchmark specifications for 4874 critical, near-critical or subcritical configurations, 31 criticality alarm placement/shielding configurations with multiple dose points for each, and 207 configurations that have been categorised as fundamental physics measurements that are relevant to criticality safety applications. New to the handbook are benchmark specifications for neutron activation foil and thermoluminescent dosimeter measurements performed at the SILENE critical assembly in Valduc, France as part of a joint venture in 2010 between the US DOE and the French Alternative Energies and Atomic Energy Commission (CEA). A photograph of this experiment is shown on the front cover. Experiments that are found unacceptable for use as criticality safety benchmark experiments are discussed in these

Clinical Experiences and Mediational Activities in Urban Teacher Preparation: Learning and Critical Consciousness

Directory of Open Access Journals (Sweden)

Craig Willey

2016-11-01

Full Text Available In a longitudinal design experiment conducted within an urban teacher preparation program, we employed ethnographic and auto-ethnographic methods to investigate the following research questions: 1 In what ways do clinical experiences (CEs support prospective teachers’ (PTs development of knowledge, skills, and dispositions necessary for urban teaching? 2 How is it determined that adjustments need to be made to the design and facilitation of CEs, and what did these adjustments yield in terms of student learning outcomes? The program centers and leverages CEs in order for PTs to connect theory and practice, particularly an awareness of, and skills associated with, equitable teaching practices. In our two-year field-based program, CEs include community explorations, one-on-one and small group work with children, two student teaching practicums, and various school-community events. We describe the iterative design process undertaken to maximize the benefits yielded from CEs. After working with three cohorts of PTs for their entire professional training, we found that: 1 focusing attention on the intentional design and assessment of the mediational activities coupled with CEs leads to more nuanced understandings and enactments of culturally relevant teaching among PTs; and 2 CEs afford PTs abundant opportunities to shape complex identities as urban teachers. Specifically, we found that clinical experiences and corresponding mediational activities support PTs’ understanding of families of color, allow them to recognize and address problematic schooling practices, and strengthen PTs’ otherwise fragile critical consciousness. We conclude that strategic interventions can provide clarity for PTs around what has, indeed, been learned at particular intervals in the program, and what is left to be developed in the final practicum and beyond.

Modeling of LVRF critical experiments in ZED-2 using WIMS9A/PANTHER and MCNP5

International Nuclear Information System (INIS)

Sissaoui, M.T.; Carlson, P.A.; Lebenhaft, J.R.

2009-01-01

The accuracy of WIMS9A/PANTHER and MCNP5 in modeling D 2 O-moderated, and H 2 O-, D 2 O- or air-cooled, doubly heterogeneous lattices of fuel clusters was demonstrated using Low Void Reactivity Fuel (LVRF) substitution experiments in the ZED-2 critical facility. MCNP5 with ENDF/B-VI (Release 5) underpredicted k eff but gave excellent coolant void reactivity (CVR) bias values. WIMS9A/PANTHER with JEF-2.2 overpredicted k eff and underpredicted the CVR bias relative to MCNP5 by 100-200 pcm. Both codes reproduced the measured axial and radial flux shapes accurately

Critical heat flux experiments for high conversion light water reactor, (3)

International Nuclear Information System (INIS)

Iwamura, Takamichi; Okubo, Tsutomu; Suemura, Takayuki; Hiraga, Fujio; Murao, Yoshio

1990-03-01

As a part of the thermal-hydraulic feasibility study of a high conversion light water reactor (HCLWR), critical heat flux (CHF) experiments were performed using triangular array rod bundles under steady-state and flow reduction transient conditions. The geometries of test sections were: rod outer diameter 9.5 mm, number of rods 4∼7, heated length 0.5∼1.0 m, and pitch to diameter ratio (P/D) 1.126∼1.2. The simulated fuel rod was a stainless steel tube and uniformly heated electrically with direct current. In the steady-state tests, pressures ranged: 1.0∼3.9 Mpa, mass velocities: 460∼4270 kg/s·m 2 , and exit qualities: 0.02∼0.35. In the transient tests, the times to CHF detection ranged from 0.5 to 25.4 s. The steady-state CHF's for the 4-rod test sections were higher than those for the 7-rod test sections with respect to the bundle averaged flow conditions. The measured CHF's increased with decreasing the heated length and decreased with decreasing the P/D. Based on the local flow conditions obtained with the subchannel analysis code COBRA-IV-I, KfK correlation agreed with the CHF data within 20 %, while WSC-2, EPRI-B and W, EPRI-Columbia and Kattor correlations failed to give satisfactory agreements. Under flow reduction rates less than 6 %/s, no significant difference in the onset conditions of DNB (departure from nucleate boiling) was recognized between the steady-state and transient conditions. At flow reduction rates higher than 6 %/s, on the other hand, the DNB occurred earlier than the DNB time predicted with the steady-state experiments. (author)

Criticality safety benchmark evaluation project: Recovering the past

Energy Technology Data Exchange (ETDEWEB)

Trumble, E.F.

1997-06-01

A very brief summary of the Criticality Safety Benchmark Evaluation Project of the Westinghouse Savannah River Company is provided in this paper. The purpose of the project is to provide a source of evaluated criticality safety experiments in an easily usable format. Another project goal is to search for any experiments that may have been lost or contain discrepancies, and to determine if they can be used. Results of evaluated experiments are being published as US DOE handbooks.

Handling Worldwide LHC Computing Grid Critical Service Incidents : The infrastructure and experience behind nearly 5 years of GGUS ALARMs

CERN Multimedia

Dimou, M; Dulov, O; Grein, G

2013-01-01

In the Wordwide LHC Computing Grid (WLCG) project the Tier centres are of paramount importance for storing and accessing experiment data and for running the batch jobs necessary for experiment production activities. Although Tier2 sites provide a significant fraction of the resources a non-availability of resources at the Tier0 or the Tier1s can seriously harm not only WLCG Operations but also the experiments' workflow and the storage of LHC data which are very expensive to reproduce. This is why availability requirements for these sites are high and committed in the WLCG Memorandum of Understanding (MoU). In this talk we describe the workflow of GGUS ALARMs, the only 24/7 mechanism available to LHC experiment experts for reporting to the Tier0 or the Tier1s problems with their Critical Services. Conclusions and experience gained from the detailed drills performed in each such ALARM for the last 4 years are explained and the shift with time of Type of Problems met. The physical infrastructure put in place to ...

Critical Landau Velocity in Helium Nanodroplets

NARCIS (Netherlands)

Brauer, N.B.; Smolarek, S.; Loginov, E.; Mateo, D.; Hernando, A.; Pi, M.; Barranco, M.; Buma, W.J.; Drabbels, M.

2013-01-01

The best-known property of superfluid helium is the vanishing viscosity that objects experience while moving through the liquid with speeds below the so-called critical Landau velocity. This critical velocity is generally considered a macroscopic property as it is related to the collective

Of blooming flowers and multiple sockets: infrastructure Integration and the Technological Imaginary

NARCIS (Netherlands)

M.J.C. Aspria (Marcello); M. de Mul (Marleen); S.A. Adams (Samantha)

2013-01-01

markdownabstractWe analyze and discuss the use of two metaphors for integration work in the development of Zorgportaal Rijnmond (ZPR), an online portal for healthcare and wellbeing in the Rotterdam Rijnmond region of the Netherlands. We view these metaphors as elements of actor-networks, and follow

Literature research concerning alternative methods for validation of criticality calculation systems

International Nuclear Information System (INIS)

Behler, Matthias

2016-05-01

Beside radiochemical analysis of irradiated fuel and critical experiments, which has become a well-established basis for the validation of depletion code and criticality codes respectively, also results of oscillation experiments or the operating conditions of power reactor and research reactors can provide useful information for the validation of the above mentioned codes. Based on a literature review the potential of the utilization of oscillation experiment measurements for the validation of criticality codes is estimated. It is found that the reactivity measurements for actinides and fission products within the CERES program on the reactors DIMPLE (Winfrith, UK) and MINERVE (Cadarache, France) can give a valuable addition to the commonly used critical experiments for criticality code validation. However, there are approaches but yet no generally satisfactory solution for integrating the reactivity measurements in a quantitative bias determination for the neutron multiplication factor of typical application cases including irradiated spent fuel outside reactor cores, calculated using common criticality codes.

Plans and equipment for criticality measurements on plutonium-uranium nitrate solutions

International Nuclear Information System (INIS)

Lloyd, R.C.; Clayton, E.D.; Durst, B.M.

1982-01-01

Data from critical experiments are required on the criticality of plutonium-uranium nitrate solutions to accurately establish criticality control limits for use in processing and handling of breeder type fuels. Since the fuel must be processed both safely and economically, it is necessary that criticality considerations be based on accurate experimental data. Previous experiments have been reported on plutonium-uranium solutions with Pu weight ratios extending up to some 38 wt %. No data have been presented, however, for plutonium-uranium nitrate solutions beyond this Pu weight ratio. The current research emphasis is on the procurement of criticality data for plutonium-uranium mixtures up to 60 wt % Pu that will serve as the basis for handling criticality problems subsequently encountered in the development of technology for the breeder community. Such data also will provide necessary benchmarks for data testing and analysis on integral criticality experiments for verification of the analytical techniques used in support of criticality control. Experiments are currently being performed with plutonium-uranium nitrate solutions in stainless steel cylindrical vessels and an expandable slab tank system. A schematic of the experimental systems is presented

Application of the Reina Trust and Betrayal Model to the experience of pediatric critical care clinicians.

Science.gov (United States)

Rushton, Cynda Hylton; Reina, Michelle L; Francovich, Christopher; Naumann, Phyllis; Reina, Dennis S

2010-07-01

Trust is essential in the workplace, yet no systematic studies of trust among pediatric critical care professionals have been done. To determine the feasibility of measuring trust in a pediatric intensive care unit by using established scales from the corporate world and to determine what behaviors build, break, and rebuild trust. The Reina Trust and Betrayal Model was used to explore contractual, competence, and communication trust. Nurses and physicians in a pediatric intensive care unit completed online surveys to measure organizational, team, and patient trust. Quantitative data from 3 standard survey instruments and qualitative responses to 3 open-ended questions were analyzed and compared. Quantitative data from all 3 instruments indicated moderate to high levels of trust; scores for competence and contractual trust were higher than scores for communication trust. Scores indicated agreement on behaviors that build trust, such as pointing out risky situations to each other, actively striving to build supportive and productive relationships, and giving and receiving constructive feedback. Foremost among trust-breaking behaviors was gossip, which was more troublesome to respondents with longer experience in critical care. Responses to the open-ended questions underscored these themes. The most frequently cited items included encouraging mutually serving intentions, sharing information, and involving and seeking the input of others. The Reina trust scales and open-ended questions are feasible and applicable to pediatric critical care units, and data collected with these instruments are useful in determining what behaviors build, break, and rebuild trust among staff.

Critical incidents and mortality reporting in pediatric anesthesia: the Australian experience.

Science.gov (United States)

Ragg, Philip

2011-07-01

Since 1960, the collection and analysis of mortality data for anesthesia in Australia has been of significant benefit to practising anesthetists. These figures include pediatric deaths which fortunately have been rare and often inevitable because of severe underlying disease and patient risk factors. The reporting of critical incidents and serious morbidity, on the other hand, has been far less impressive. Only one state in Australia, Victoria, currently has a committee that collects morbidity data and, as this reporting is voluntary, is likely to under-represent the true numbers of critical events. There is no specific pediatric morbidity database in Australia so much of this discussion will be regarding overall anesthesia critical event reporting which includes pediatrics as a subset. © 2011 Blackwell Publishing Ltd.

CAMAC-controlled calibration system for nuclear reactor instruments

International Nuclear Information System (INIS)

McDowell, W.P.; Cornella, R.J.

1977-01-01

The hardware and the software which have been developed to implement a nuclear instrument calibration system for the Argonne National Laboratory ZPR-VI and ZPR-IX reactor complex are described. The system is implemented using an SEL-840 computer with its associated CAMAC crates and a hardware interface to generate input parameters and measure the required outputs on the instrument under test. Both linear and logarithmic instruments can be calibrated by the system and output parameters can be measured at various automatically selected values of ac line voltage. A complete report on each instrument is printed as a result of the calibration and out-of-tolerance readings are flagged. Operator interface is provided by a CAMAC-controlled Hazeltine terminal. The terminal display leads the operator through the complete calibration procedure. This computer-controlled system is a significant improvement over previously used methods of calibrating nuclear instruments since it reduces reactor downtime and allows rapid detection of long-term changes in instrument calibration

KAFAX-F22 : development and benchmark of multi-group library for fast reactor using JEF-2.2. Neutron 80 group and Photon 24 group

International Nuclear Information System (INIS)

Kim, Jung Do; Gil, Choong Sup.

1997-03-01

The KAFAX-F22 was developed from JEF-2.2, which is a MATXS format, multigroup library of fast reactor. The KAFAX-F22 has 80 and 24 energy group structures for neutron and photon, respectively. It includes 89 nuclide data processed by NJOY94.38. The TRANSX/TWODANT system was used for benchmark calculations of fast reactor and one- and two-dimensional calculations of ONEDANT and TWODANT were carried out with 80 group, P 3 S 16 and with 25 group, P 3 S 8 , respectively. The average values of multiplication factors are 0.99652 for MOX cores, 1.00538 for uranium cores and 1.00032 for total cores. Various central reaction rate ratios also give good agreements with the experimental values considering experimental uncertainties except for VERA-11A, VERA-1B, ZPR-6-7 and ZPR-6-6A cores of which experimental values seem to involve some problems. (author). 13 refs., 18 tabs., 2 figs

ChatBot Based on Language Modelling

OpenAIRE

Radvanský, Matěj

2014-01-01

Tato práce řeší využití jazykového modelování v chatbotovi pomocí neuronových sítí. Tento problém je řešen tak, že pomocí zpracování přirozeného jazyka je při vytváření odpovědi na uživatelskou zprávu prvně zpráva analyzována. Poté jsou vytvořeny počátky vět odpovědi, které jsou doplněny výstupem neuronové sítě. Dohromady tyto věty tvoří odpověď chatbota. Proběhlo porovnání s existujícím chatbotem Cleverbotem a byla zjišťována míra inteligence obou chatbotů, na jejichž základě jsou uvedeny mo...

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)

Interpretation of criticality experiments on homogeneous solutions of plutonium and uranium; Interpretation des experiences de criticite sur des solutions homogenes de plutonium et d'uranium

Energy Technology Data Exchange (ETDEWEB)

Ithurralde, M F; Kremser, J; Leclerc, J; Lombard, Ch; Moreau, J; Robin, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

Criticality experiments on solutions of fissionable materials have been carried out in tanks of various geometries (cylinder, isolated annular cylinder, interacting annular cylinders); the reflexion conditions have also been varied (without reflection, semi-reflection and total reflexion by water). The range of the studied concentrations is rather large (18,8 to 104 gms/liter). The interpretation of these experiments has been undertaken in order to resolve the problems of the industrial use of homogeneous plutonium and uranium solutions. Several methods the fields of application of which are different have been used: diffusion method, transport method and Monte-Carlo method. (authors) [French] Des experiences critiques sur des solutions de matieres fissiles ont ete faites dans des cuves de diverses geometries (cylindre, cylindre annulaire isole, cylindre annulaire en interaction), les conditions de reflexion ont ete egalement variees (sans reflexion, semi reflexion et reflexion totale par l'eau). La gamme des concentrations etudiees est assez etendue (18,8 a 104 g/l ). L'interpretation de ces experiences a ete entreprise dans le but de pouvoir resoudre les problemes poses par l'emploi industriel de solutions homogenes de plutonium et d'uranium, plusieurs methodes dont les domaines d'application sont differents ont ete employees: methode de diffusion, methode de transport, methode de Monte-Carlo. (auteurs)

Women's experience of rage: a critical feminist analysis.

Science.gov (United States)

Flemke, Kimberly; Allen, Katherine R

2008-01-01

We conducted in-depth interviews with 37 incarcerated women on their experience of rage towards their intimate partner. Participants used specific criteria to distinguish their experience of rage from anger. Rage is described as an overwhelming experience with particular physiological and cognitive changes that takes control of a woman's emotions and actions. In contrast, anger is described as a controllable emotion with a specific termination point. Motivations for acting violently in rage with an intimate partner are described and discussed. Findings suggest a primary trigger for experiencing rage is feeling threatened and feeling emotionally overwhelmed.

ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

Energy Technology Data Exchange (ETDEWEB)

Kahler, A.C.; Herman, M.; Kahler,A.C.; MacFarlane,R.E.; Mosteller,R.D.; Kiedrowski,B.C.; Frankle,S.C.; Chadwick,M.B.; McKnight,R.D.; Lell,R.M.; Palmiotti,G.; Hiruta,H.; Herman,M.; Arcilla,R.; Mughabghab,S.F.; Sublet,J.C.; Trkov,A.; Trumbull,T.H.; Dunn,M.

2011-12-01

The ENDF/B-VII.1 library is the latest revision to the United States Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [M. B. Chadwick et al., 'ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data,' Nuclear Data Sheets, 112, 2887 (2011)]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project's International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected {sup 235}U and {sup 239}Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also

Association between age, critical skills and work perspectives

Directory of Open Access Journals (Sweden)

S Krüger

2014-01-01

Full Text Available The main aim of this study is to report on the associations between age, critical skills and work perspectives (job satisfaction, career/organizational commitment and job characteristics as perceived by resort employees. It highlights that age and critical skills play an important role towards work perspectives. A descriptive research design approach was followed. Three hundred and eighteen fully completed questionnaires were included in the statistical analysis, which included exploratory factor analysis, Spearman's rho and a structural equation model. Resort employees of different ages do not experience job characteristics differently. Older employees are often more experienced in the work environment, which contributes to an increase in job satisfaction, while younger employees who start building a career in the hospitality sector experience less job satisfaction. Older employees are more committed to their careers than younger employees. Critical skills have no influence on participants' perception of job characteristics. However, resort employees who have a variety of critical skills experience an increase in job satisfaction.

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)

Alize 3 - first critical experiment for the franco-german high flux reactor - calculations

International Nuclear Information System (INIS)

Scharmer, K.

1969-01-01

The results of experiments in the light water cooled D 2 O reflected critical assembly ALIZE III have been compared to calculations. A diffusion model was used with 3 fast and epithermal groups and two overlapping thermal groups, which leads to good agreement of calculated and measured power maps, even in the case of strong variations of the neutron spectrum in the core. The difference of calculated and measured k eff was smaller than 0.5 per cent δk/k. Calculations of void and structure material coefficients of the reactivity of 'black' rods in the reflector, of spectrum variations (Cd-ratio, Pu-U-ratio) and to the delayed photoneutron fraction in the D 2 O reflector were made. Measurements of the influence of beam tubes on reactivity and flux distribution in the reflector were interpreted with regard to an optimum beam tube arrangement for the Franco- German High Flux Reactor. (author) [fr

Some problems of neutron source multiplication method for site measurement technology in nuclear critical safety

International Nuclear Information System (INIS)

Shi Yongqian; Zhu Qingfu; Hu Dingsheng; He Tao; Yao Shigui; Lin Shenghuo

2004-01-01

The paper gives experiment theory and experiment method of neutron source multiplication method for site measurement technology in the nuclear critical safety. The measured parameter by source multiplication method actually is a sub-critical with source neutron effective multiplication factor k s , but not the neutron effective multiplication factor k eff . The experiment research has been done on the uranium solution nuclear critical safety experiment assembly. The k s of different sub-criticality is measured by neutron source multiplication experiment method, and k eff of different sub-criticality, the reactivity coefficient of unit solution level, is first measured by period method, and then multiplied by difference of critical solution level and sub-critical solution level and obtained the reactivity of sub-critical solution level. The k eff finally can be extracted from reactivity formula. The effect on the nuclear critical safety and different between k eff and k s are discussed

Criticality Model

International Nuclear Information System (INIS)

Alsaed, A.

2004-01-01

The ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, ''Models'', in that they are procedural, rather than mathematical. These model reports document the detailed methodology necessary to implement the approach presented in the Disposal Criticality Analysis Methodology Topical Report and provide calculations utilizing the methodology. Thus, the governing procedure for this type of report is AP-3.12Q, ''Design Calculations and Analyses''. The ''Criticality Model'' is of this latter type, providing a process evaluating the criticality potential of in-package and external configurations. The purpose of this analysis is to layout the process for calculating the criticality potential for various in-package and external configurations and to calculate lower-bound tolerance limit (LBTL) values and determine range of applicability (ROA) parameters. The LBTL calculations and the ROA determinations are performed using selected benchmark experiments that are applicable to various waste forms and various in-package and external configurations. The waste forms considered in this calculation are pressurized water reactor (PWR), boiling water reactor (BWR), Fast Flux Test Facility (FFTF), Training Research Isotope General Atomic (TRIGA), Enrico Fermi, Shippingport pressurized water reactor, Shippingport light water breeder reactor (LWBR), N-Reactor, Melt and Dilute, and Fort Saint Vrain Reactor spent nuclear fuel (SNF). The scope of this analysis is to document the criticality computational method. The criticality

Torn between dual roles: the experiences of nurse-family members when a loved one is hospitalised in a critical condition.

Science.gov (United States)

Giles, Tracey M; Williamson, Victoria

2015-11-01

To understand and interpret the experiences of nurse-family members when a family member or loved one is hospitalised in a critical condition. Having a family member hospitalised with a critical illness is a traumatic stressor, often with long-term sequelae. Providing holistic care for family members who are also nurses makes the provision of care more complex because of their professional expertise; yet few studies have explored this issue. In this descriptive study, qualitative data were collected using a questionnaire and analysed using van Manen's (Researching Lived Experience: Human Science for an Action Sensitive Pedagogy, 1990, State University of New York Press, London, ON) six-step approach. Twenty nurse-family members completed an online questionnaire in June 2013. Qualitative findings from 19 participants were included in the analysis. The phenomenological analysis approach described by van Manen (Researching Lived Experience: Human Science for an Action Sensitive Pedagogy, 1990, State University of New York Press, London, ON) was used to describe and interpret nurse-family member experiences. Nurse-family members experience significant dual role conflicts between their personal and professional personas due to their specialised knowledge, need for watchfulness and competing expectations. Our findings describe how dual role conflicts developed and were managed, and reveal the resultant emotional toll and psychological distress as nurse-family members struggled to resolve these conflicts. Nurse-family members require a different type of care than general public family members, yet their unique needs are often unmet, leading to increased anxiety and distress that could potentially be minimised. An increased awareness and emphasis on the nurse-family member experience can ensure health care professionals are better placed to provide appropriate and targeted care to minimise distressing dual role conflicts. There is a need for targeted and specialised

Proceedings of the nuclear criticality technology safety project

Energy Technology Data Exchange (ETDEWEB)

Sanchez, R.G. [comp.

1997-06-01

This document contains summaries of the most of the papers presented at the 1994 Nuclear Criticality Technology Safety Project (NCTSP) meeting, which was held May 10 and 11 at Williamsburg, Va. The meeting was broken up into seven sessions, which covered the following topics: (1) Validation and Application of Calculations; (2) Relevant Experiments for Criticality Safety; (3) Experimental Facilities and Capabilities; (4) Rad-Waste and Weapons Disassembly; (5) Criticality Safety Software and Development; (6) Criticality Safety Studies at Universities; and (7) Training. The minutes and list of participants of the Critical Experiment Needs Identification Workgroup meeting, which was held on May 9 at the same venue, has been included as an appendix. A second appendix contains the names and addresses of all NCTSP meeting participants. Separate abstracts have been indexed to the database for contributions to this proceedings.

Proceedings of the nuclear criticality technology safety project

International Nuclear Information System (INIS)

Sanchez, R.G.

1997-06-01

This document contains summaries of the most of the papers presented at the 1994 Nuclear Criticality Technology Safety Project (NCTSP) meeting, which was held May 10 and 11 at Williamsburg, Va. The meeting was broken up into seven sessions, which covered the following topics: (1) Validation and Application of Calculations; (2) Relevant Experiments for Criticality Safety; (3) Experimental Facilities and Capabilities; (4) Rad-Waste and Weapons Disassembly; (5) Criticality Safety Software and Development; (6) Criticality Safety Studies at Universities; and (7) Training. The minutes and list of participants of the Critical Experiment Needs Identification Workgroup meeting, which was held on May 9 at the same venue, has been included as an appendix. A second appendix contains the names and addresses of all NCTSP meeting participants. Separate abstracts have been indexed to the database for contributions to this proceedings

Modeling of LVRF Critical Experiments in ZED-2 Using WIMS9A/PANTHER and MCNP5

International Nuclear Information System (INIS)

Sissaoui, M.T.; Lebenhaft, J.R; Carlson, P.A.

2008-01-01

The accuracy of WIMS9A/PANTHER and MCNP5 in modeling D 2 O-moderated, and H 2 O-, D 2 O- or air-cooled, doubly heterogeneous lattices of fuel clusters was demonstrated using Low Void Reactivity Fuel (LVRF) substitution experiments in the ZED-2 critical facility. MCNP5 with ENDF/B-VI (Release 5) under-predicted k eff but gave excellent coolant void reactivity (CVR) bias values. WIMS9A/PANTHER with JEF-2.2 over-predicted k eff and under-predicted the CVR bias relative to MCNP5 by 100 pcm to 200 pcm. Both codes reproduced the measured axial and radial flux shapes accurately. (authors)

Realistic evaluation of new fuel storage criticality

International Nuclear Information System (INIS)

Hamasaki, M.; Itahara, K.; Shimada, S.; Etsu, M.; Kuroda, M.; Watanabe, H.; Kuragasaki, M.; Kawaguchi, K.

1987-01-01

In the criticality safety design of dry fuel storage facility, the optimum moderation condition which appears at rather low water density (0.05 ∼ 0.1 gH 2 O/cc) has been a barrier to incorporate economical design. In this study we have shown that this optimum moderation does not occur, even in fire-fighting with water supply system, by criticality analyses and experiments. Evaluated critical amount of water in the space has found itself far from the level estimated actually attainable through the experiment with fire-fighting system. In another experiment we have taken the holograms of 0.003 ∼ 0.35 g/cc water which was realized in the very narrow space by the nozzle manufactured for this special purpose. Those holograms demonstrate that the droplets in the low density water are more closely packed than we anticipate they are. (author)

Criticality Benchmark Analysis of Water-Reflected Uranium Oxyfluoride Slabs

International Nuclear Information System (INIS)

Marshall, Margaret A.; Bess, John D.

2009-01-01

A series of twelve experiments were conducted in the mid 1950's at the Oak Ridge National Laboratory Critical Experiments Facility to determine the critical conditions of a semi-infinite water-reflected slab of aqueous uranium oxyfluoride (UO2F2). A different slab thickness was used for each experiment. Results from the twelve experiment recorded in the laboratory notebook were published in Reference 1. Seven of the twelve experiments were determined to be acceptable benchmark experiments for the inclusion in the International Handbook of Evaluated Criticality Safety Benchmark Experiments. This evaluation will not only be available to handbook users for the validation of computer codes and integral cross-section data, but also for the reevaluation of experimental data used in the ANSI/ANS-8.1 standard. This evaluation is important as part of the technical basis of the subcritical slab limits in ANSI/ANS-8.1. The original publication of the experimental results was used for the determination of bias and bias uncertainties for subcritical slab limits, as documented by Hugh Clark's paper 'Subcritical Limits for Uranium-235 Systems'.

The spent fuel safety experiment

International Nuclear Information System (INIS)

Harmms, G.A.; Davis, F.J.; Ford, J.T.

1995-01-01

The Department of Energy is conducting an ongoing investigation of the consequences of taking fuel burnup into account in the design of spent fuel transportation packages. A series of experiments, collectively called the Spent Fuel Safety Experiment (SFSX), has been devised to provide integral benchmarks for testing computer-generated predictions of spent fuel behavior. A set of experiments is planned in which sections of unirradiated fuel rods are interchanged with similar sections of spent PWR fuel rods in a critical assembly. By determining the critical size of the arrays, one can obtain benchmark data for comparison with criticality safety calculations. The integral reactivity worth of the spent fuel can be assessed by comparing the measured delayed critical fuel loading with and without spent fuel. An analytical effort to model the experiments and anticipate the core loadings required to yield the delayed critical conditions runs in parallel with the experimental effort

Therapists' experiences and perceptions of teamwork in neurological rehabilitation: critical happenings in effective and ineffective teamwork.

Science.gov (United States)

Suddick, Kitty M; De Souza, Lorraine H

2007-12-01

This paper reports the second part of an exploratory study into occupational therapists' and physiotherapists' perceptions and experiences of teamwork in neurological rehabilitation: the factors that were thought to influence effective and ineffective teamwork, and the meaning behind effective and ineffective teamwork in neurological rehabilitation. The study was undertaken through semi-structured interviews of 10 therapists from three different neurological rehabilitation teams based in the United Kingdom, and used the critical incident technique. Through analysis of the data, several main themes emerged regarding the perceived critical happenings in effective and ineffective teamwork. These were: team events and characteristics, team members' characteristics, shared and collaborative working practices, communication, specific organizational structures, environmental, external, and patient and family-related factors. Effective and ineffective team-work was perceived to impact on a number of levels: having implications for the team, the patient, individual team members, and the neurological rehabilitation service. The study supported the perceived value of team work within neurological rehabilitation. It also indicated the extensive and variable factors that may influence the team-working process as well as the complex and diverse nature of the process.

Stepping up for Childhood: A Contextual Critical Methodology

Science.gov (United States)

Kyriacopoulos, Konstantine; Sánchez, Marta

2017-01-01

In this paper, we theorize a critical methodology for education centering community experiences of systemic injustice, drawing upon Critical Race Theory, critical educational leadership studies, Chicana feminism, participant action research and political theory, to refocus our work on the human relationships at the center of the learning and…

IEA Wind Task 23 Offshore Wind Technology and Deployment. Subtask 1 Experience with Critical Deployment Issues. Final Technical Report

OpenAIRE

Lemming, Jørgen Kjærgaard

2010-01-01

The final report for IEA Wind Task 23, Offshore Wind Energy Technology and Deployment, is made up of two separate reports: Subtask 1: Experience with Critical Deployment Issues and Subtask 2: Offshore Code Comparison Collaborative (OC3). The Subtask 1 report included here provides background information and objectives of Task 23. It specifically discusses ecological issues and regulation, electrical system integration and offshore wind, external conditions, and key conclusions for Subtask 1. ...

Critical Care Organizations: Business of Critical Care and Value/Performance Building.

Science.gov (United States)

Leung, Sharon; Gregg, Sara R; Coopersmith, Craig M; Layon, A Joseph; Oropello, John; Brown, Daniel R; Pastores, Stephen M; Kvetan, Vladimir

2018-01-01

New, value-based regulations and reimbursement structures are creating historic care management challenges, thinning the margins and threatening the viability of hospitals and health systems. The Society of Critical Care Medicine convened a taskforce of Academic Leaders in Critical Care Medicine on February 22, 2016, during the 45th Critical Care Congress to develop a toolkit drawing on the experience of successful leaders of critical care organizations in North America for advancing critical care organizations (Appendix 1). The goal of this article was to provide a roadmap and call attention to key factors that adult critical care medicine leadership in both academic and nonacademic setting should consider when planning for value-based care. Relevant medical literature was accessed through a literature search. Material published by federal health agencies and other specialty organizations was also reviewed. Collaboratively and iteratively, taskforce members corresponded by electronic mail and held monthly conference calls to finalize this report. The business and value/performance critical care organization building section comprised of leaders of critical care organizations with expertise in critical care administration, healthcare management, and clinical practice. Two phases of critical care organizations care integration are described: "horizontal," within the system and regionalization of care as an initial phase, and "vertical," with a post-ICU and postacute care continuum as a succeeding phase. The tools required for the clinical and financial transformation are provided, including the essential prerequisites of forming a critical care organization; the manner in which a critical care organization can help manage transformational domains is considered. Lastly, how to achieve organizational health system support for critical care organization implementation is discussed. A critical care organization that incorporates functional clinical horizontal and

Safe Space Oddity: Revisiting Critical Pedagogy

Science.gov (United States)

Redmond, Melissa

2010-01-01

Inspired by an incident in a social work graduate classroom in which she was a teaching assistant, the author reflects on her commitment to constructivist teaching methods, critical theory, and critical pedagogy. Exploring the educational utility of notions such as public space and safe space, the author employs this personal experience to examine…

Úhlová diskordance v malesických vrstvách v mšensko-roudnické a žihelské pánve (stephan B)