bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation shielding is not a solution – radiation protection of air crews
Authors: Boehm Th. 
Published: December 2013

Abstract
In most working environments it is fairly easy to minimize radiation doses of workers as postulated by radiation protection basics: Increasing the distance to the radiation source, reducing the exposure time, and the use of protective clothing or shielding. With air crews however, being the largest group of exposed persons and receiving the highest collective doses, classical protective measures are difficult or even impossible to enforce. Without neglecting the economical situation, effective measures could nevertheless be realized. Planning flights at slightly lower altitudes and further away from the geomagnetic poles can significantly reduce the radiation exposure for both crew and passengers. Furthermore, affordable high-quality dosimeters with the size of mobile phones have reached marketability. If installed on board, they could measure and display the actually received radiation during normal operation and additionally warn the flight crew in case of an abnormally high dose rate during solar particle events. Pilots could react to such warnings according to procedures that are yet to be installed.
Radon at workplaces in Bavaria and experiences with remediation
Authors: Körner S. , Reifenhäuser C. 
Published: December 2013

Abstract
In Germany radon exposure at certain workplaces has been regulated by the Radiation Protection Ordinance since 2001. However in Bavaria studies have been conducted since 1996. The radon exposure of all staff concerned was estimated and thereby several companies were identified where the exposure exceeded 6 mSv per year. Since then the exposure of the staff has been continuously monitored in these companies. Remediation measures specifically adjusted to local conditions led to a reduction of the exposure in many of these companies. Therefore only in 11 of the original 81 companies exposures of more than 6 mSv/a persist until today. As the Bavarian Environment Agency (LfU) oversaw the measurements and remediation measures there exists profound knowledge within the LfU of the local conditions mainly in water supply facilities as well as of the various remediation measures and their success. Furthermore, a few investigations concerning radon are carried out at workplaces not regulated by the Radiation Protection Ordinance. As an example we present a town hall where the measured radon concentrations led to a heated public dispute. Here the LfU successfully communicated factual information and the evaluation of the radon situation with regard to international recommendations.
Heat transfer study of a submerged reactor channel under boil-off condition
Authors: Mukhopadhyay D. , Sahoo P. K. , Ghosh A. K. 
Published: December 2013

Abstract
Experiments have been carried out to study the heatup behavior of a single segmented reactor channel for Pressurized Heavy Water Reactor under submerged, partially submerged and exposed conditions. This situation may arise from a severe accident scenario of Pressurised Heavy Water Reactors where full or segmented reactor channels are likely to be disassembled and form a submerged debris bed. An assembly of electrical heater rod, simulating fuel bundle and channel components like Pressure Tube and Calandria Tube constitutes the segmented reactor channel. Heatup of this assembly is observed with respect to different water levels ranging from full submergence to totally exposed and power levels of 6–8 kW, typical to decay power level. It has been observed from the set of experiment that fuel bundle local dry out followed by heatup does not happen till the bundle is partially submerged. Temperature excursion of the bundle is evident when the bundle is exposed to steam-air environment.
Modelling, simulation and experiments on boiling processes in pressurized water reactors
Authors: Krepper E. 
Published: December 2013

Abstract
A collaborative project funded by the Federal Ministry of Education and Research (BMBF) in the framework of the R&D program “Energie 2020+” by four Universities, two Research Centres and ANSYS is coordinated by Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The project is directed towards the development and validation of CFD models of boiling processes in PWR in the range from subcooled nucleate boiling up to the critical heat flux. The work is oriented towards basic research and focused on model development, simulation and experiments on different scales. An important objective is the education and maintaining of competence in nuclear technology.
CFD-modelling of subcooled boiling
Authors: Krepper E. , Rzehak R. , Lifante C. , Frank Th. 
Published: December 2013

Abstract
In this paper new developments in the framework of a common project simulating subcooled boiling are described. The computational model used combines the Euler/Euler two-phase flow description with heat flux partitioning. Main achievements were a comprehensive study of the boiling process itself and a better description of the interfacial area by coupling of wall boiling with a population balance model. The model extensions are validated and the present capabilities of CFD for wall boiling are investigated.
Small scale boiling experiments using two-dimensional imaging with high-speed camera and optical coherence tomography
Authors: Schneider C. , Kirsten L. , Meissner S. , Hurtado A. , Koch E. , Hampel R. 
Published: December 2013

Abstract
To investigate boiling processes, a test facility has been constructed, which allows the use of optical techniques for the detection of individual vapor bubbles. Demineralized water was used as working fluid at ambient pressure whereat temperature, flow rate and heat flux density can be varied. The growth of individual vapor bubbles was recorded by high-speed camera and analyzed by digital image processing (DIP). Optical coherence tomography (OCT) enabled the visualization of steam bubbles in cross-sections perpendicular to the heated surface.
CFD-Modeling of turbulent flows in rod bundle and comparison to experiments
Authors: Lifante C. , Krull B. , Frank T. , Franz R. , Hampel U. 
Published: December 2013

Abstract
Turbulent single-phase simulations in a geometrical domain reproducing the new ROFEX test facility (3×3 rod bundle) were conducted. These investigations were aimed to perform an initial study for future analysis of boiling processes in the same test facility. The final goal of these experiments in ROFEX is the validation of CFD boiling models. The current CFD simulations allow an assessment of the turbulent flow conditions in this test facility.
Simulation of external reactor vessel cooling in a lumped-parameter code
Authors: Schittek U. , Koch M. K. 
Published: December 2013

Abstract
In the course of a severe accident in a nuclear power plant the integrity of the reactor vessel may be preserved by External Reactor Vessel Cooling (ERVC). By flooding the cavity surrounding the reactor vessel the decay heat is removed from molten core material through the vessel wall to water at the submerged vessel surface. In order to simulate the boiling process at the external vessel wall during ERVC in the framework of lumped parameter codes a model based on a boiling model used in the code ANSYS CFX 13.0 is developed.
External hazards – in focus after the Fukushima accident
Authors: Krauß M. , Berg H. P. 
Published: December 2013

Abstract
International experience has shown that external hazards can be safety significant contributors to the risk of industrial plants with a high potential of damage to the environment; this has become evident after the Fukushima accident. As a consequence main focus has been set on adequate design measures against external hazards and appropriate assessment methods. Possible methods to analyse existing plants systematically regarding the adequacy of their existing protection equipment against hazards can be deterministic as well as probabilistic. On international level, new recommendations regarding external hazards are recently issued. In that context, in particular earthquakes and flooding scenarios have been re-evaluated to some extent. Also in Germany, a revised guideline on probabilistic safety analyses (PSA) and corresponding technical documents are issued in 2005 addressing external hazards. As a reaction to the accidents in Japan in March 2011, the German Reactor Safety Commission has issued a catalogue of requirements for plant-specific reviews of German nuclear power plants, and the status of the plants have been evaluated with respect to these requirements. The results of these investigations have been the basis for the German report in the frame of the European stress tests; the results with respect to natural external hazards are presented.
Frequency of damage by external explosion hazards based on geographical information
Authors: Becker G. , Camarinopoulos A. , Camarinopoulos L. , Karali T. , Schubert B. 
Published: December 2013

Abstract
External explosions can significantly contribute to risk of damage for industrial plants. External explosions may origin from other plants in the neighbourhood, which store and operate with explosive substances, or from transport of such substances on road, rail, or water. If deflagration is involved, ignition will not necessarily occur at the place of the accident, but a cloud of a combustible gas-air mixture may develop, which will ignite at some distance depending on wind velocity. A probabilistic model has been developed to calculate frequencies of damage based on numerical integration or on Monte Carlo simulation. Geographical information systems provide map material for sites, roads, rail and rivers on a computer. Data has been collected and applied for a nuclear power plant in Germany as an example. The method, however, can be used for any type of plant subject to external explosion hazards.
Investigation of neutronic effects in structural material of a hybrid reactor by using the MCNPX Monte Carlo transport code
Authors: Günay M. 
Published: December 2013

Abstract
In this study, 98–90% Li2BeF4-2–10% ThF4, 98–90% Li2BeF4-2–10% UF4, 98–90% Li2BeF4-2–10% UO2 and 100% Li2BeF4 molten salt-heavy metal was used as fluid. The fluids were used in the liquid first wall, liquid second wall and shield zones of the designed hybrid reactor system. A steel wall of 4 cm thickness is used as structural material. Proton, deuterium, tritium, He-3 and He-4 gas production rates are the parameters of radiation damage. In the study, the effect of liquid second wall thicknesses (20 cm, 30 cm, 40 cm, 50 cm) on the neutron flux distribution and the parameters of radiation damage according to neutron energy spectrum in the structural material were investigated for the selected fluids. A three-dimensional analysis was done by using the most recent version of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.
Chemistry aspects of the source term formation for a severe accident in a CANDU type reactor
Authors: Constantin A. , Constantin M. 
Published: December 2013

Abstract
The progression of a severe accident in a CANDU type reactor is slow because the core is surrounded by a large quantity of heavy and light water which acts as a heat sink to remove the decay heat. Therefore, the source term formation is a complex and long process involving fission products transport and releasing in the fuel matrix, thermal hydraulics of the transport fluid in the primary heat system and containment, deposition and transport of fission products, chemistry including the interaction with the dousing system, structural materials and paints, etc. The source term is strongly dependent on initial conditions and accident type. The paper presents chemistry aspects for a severe accident in a CANDU type reactor, in terms of the retention in the primary heat system. After releasing from the fuel elements, the fission products suffer a multitude of phenomena before they are partly transferred into the containment region. The most important species involved in the deposition were identified. At the same time, the influence of the break position in the transfer fractions from the primary heat system to the containment was investigated.
Calculation of age-dependent effective doses for external exposure using the MCNP code
Authors: Van Hung Tran 
Published: December 2013

Abstract
Age-dependent effective dose for external exposure to photons uniformly distributed in air were calculated. Firstly, organ doses were calculated with a series of age-specific MIRD-5 type phantoms using the Monte Carlo code MCNP. The calculations were performed for mono-energetic photon sources with source energies from 10 keV to 5 MeV and for phantoms of newborn, 1, 5, 10, and 15 years-old and adult. Then, the effective doses to the different age-phantoms from the mono-energetic photon sources were estimated based on the obtained organ doses. From the calculated results, it is shown that the effective doses depend on the body size; the effective doses in younger phantoms are higher than those in the older phantoms, especially below 100 keV.
T
N approximation for the critical size of one-speed neutrons in a slab with anisotropic scattering
Authors: Öztürk H. 
Published: December 2013

Abstract
The critical thickness for one-speed neutrons in a uniform finite slab with anisotropic scattering is investigated using Marshak boundary condition. The angular part of the neutron angular flux is expanded in terms of the Chebyshev polynomials of first kind. Numerical results for the critical thickness of the slab are calculated for various values of the collision and the anisotropy parameters and they are given in the tables together with the ones obtained by Legendre polynomials approximation and the ones available in literature for comparison. The results obtained by the present method are in good accordance with the literature values.
Experimental investigations on control of flow instability in single-phase natural circulation loop
Authors: Bodkha K. , Kumar N. , Vijayan P. K. 
Published: December 2013

Abstract
Natural circulation systems offer simplicity, enhanced safety and reliability and thus are advantageous over their forced circulation counterpart. However, natural circulation is susceptible to flow instabilities. These instabilities are undesirable for various reasons. Literature suggests the use of orifices at the inlet to suppress instability. However, orificing introduces pressure drop which limits the flow rate and hence the heat carrying capacity of the fluid. In the present study, investigations have been carried out with different mechanical gadgets to control the natural circulation flow instabilities. Extensive experiments have been carried out in a single-phase rectangular natural circulation loop to study the effect of these mechanical gadgets on instability. The paper brings out the results of experimental investigations carried out on the role of mechanical gadgets in controlling instability.
Analytical study on degraded core quenching
Authors: Gokhale O. S. , Puranik B. P. , Ghosh A. K. 
Published: December 2013

Abstract
Severe accident analysis of a reactor helps in emergency planning and evolution of Severe Accident Management Guidelines (SAMG). Actions recommended in the SAMG aim at arresting accident progression and limiting significant radioactive release. However, success of these SAMG actions needs to be assessed with respect to the evolution of accident. Analysis of consequences of injection of water into the reactor pressure vessel from bottom only as a SAMG action has been carried out for VVER-1000 (V320) reactor. The analysis shows that the success of this SAMG action depends not only on the state of core degradation at the time of injection, but also on the highest temperature reached in the reactor core at the time of injection as well as the availability of steam in the RPV.
Results of precision calculations of three-dimensional power density in VVER-1000 core with feedbacks using MCU code
Authors: Bikeev A. S. , Shkarovsky D. A. 
Published: December 2013

Abstract
Accounting of feedbacks on the density and temperature of the coolant, the fuel temperature, as well as on the equilibrium concentration of xenon is important for VVER reactors, since it has a significant influence on the neutron-physical characteristics of such systems. Therefore, there is a need to incorporate feedbacks into precision calculations of the power density of the VVER-1000 core. In the present work, we used a model of the core, divided into 30 layers by height. The calculations were carried out by means of Russian Monte Carlo code MCU (Monte-Carlo Universal). Individual values of densities and temperatures of the coolant, the fuel temperatures, as well as the equilibrium concentration of xenon were calculated in each layer of every fuel assembly. In addition, power density was calculated pin-by-pin in each layer. The obtained results were compared to the results obtained by means of the certified BIPR-7A code. It is shown that within a reasonable computational time using currently available hardware resources one can obtain the three-dimensional power density with an acceptable accuracy and taking into account the feedbacks on the density and temperature of the coolant, the fuel temperature, as well as the equilibrium concentration of xenon.
A comparison of the FA's models with the detailed and simplified description in the MCU code calculations
Authors: Bikeev A. S. , Marin S. V. , Sukhino-Khomenko E. A. 
Published: December 2013

Abstract
Full-scale three-dimensional computer model describing neutron-physical processes that occur in the VVER-1200 reactor core involves detailed FA geometry description. However, the detailed description significantly complicates input data, increases calculation time and error probability. Consequently, creation of simplified models of the design elements becomes necessary. In present work, simplified geometrical models of FA design elements are suggested. Calculations of simplified models are compared to calculations of exact models that completely correspond to the working general view drafts provided by OKB “Hydropress”. It is demonstrated that in many problems the use of simplified description of FA elements geometry is possible.
Account for uncertainties of control measurements in the assessment of design margin factors
Authors: Dementiev V. , Sidorenko V. , Shishkov L. 
Published: December 2013

Abstract
This paper considers two interrelated issues and – proceeding from the conditional probability concept and Bayes’ statistical theorem – suggests a universal method to process measured data with account of prior information available. To assure reliable reactor operation, at the design stage it is suggested to account for errors of subsequent control measurements while assessing the engineering margin factors for reactor parameters to be measured.
Solid-state reaction in Ni/Si multilayered films, characterized by magneto-optical and optical spectroscopies
Authors: Lee Young Pak , BaeKim Jin , Yoo Young Joon , Kudryavtsev Yuri V. 
Published: December 2013

Abstract
Solid-state reactions, induced by ion-beam mixing (IBM) and thermal annealing, in Ni/Si multilayered films (MLF) with an overall stoichiometry of Ni2Si, NiSi and NiSi2, and with a constant Ni sublayer thickness (nominally, 3.0 nm), were studied by optical and magneto-optical spectroscopies as well as X-ray diffraction (XRD). The layer mixing was performed with Ar+ ions of an energy of 80 keV and a dose of 1.5 × 1016 Ar+/cm2. It was shown that the IBM leads to structural changes in the Ni/Si MLF, which cannot be easily detected by XRD but are recognized by optical tools. An annealing at 1073 K of the Ni/Si MLF with an overall stoichiometry of NiSi and NiSi2 induces formation of predominantly the η-NiSi and the NiSi2 phases, respectively. IBM of all the investigated Ni/Si MLF leads to the formation of regions with a short-range order of the crystalline NiSi silicide, and of Ni2Si (and/or Ni3Si) additionally for the Ni/Si MLF with an overall stoichiometry of Ni2Si.
Effects of an electric field applied during the solution heat treatment of the Al–Mg–Si–Cu alloy AA 6111 on the subsequent natural aging kinetics and tensile properties
Authors: Jung Kang , Conrad Hans 
Published: December 2013

Abstract
The effects of an external dc electric field of 0–5 kV/cm, applied at 475–550°C during solution heat treatment (SHT) to AA6111, on the subsequent natural aging kinetics and volume fraction of precipitated clusters were determined employing resistivity. The field increased the as-quenched resistivity and that during natural aging, the effect being significant from 0 to ≈0.5 kV/cm and increasing only slightly, if at all, thereafter. An Avrami-type analysis of the natural aging kinetics gave n = 0.59 ± 0.2 and k = (1.2 ± 0.8) · 10−2 min−1, relatively independent of SHT temperature and field strength. The field increased the volume fraction of precipitated clusters which occurred during natural aging. This was attributed to the increase in solubility during SHT produced by the field. Tensile properties equivalent to those obtained by the SHT at 550°C without a field were obtained at 500°C with a field of only 200 V/cm, representing a reduction of 50°C in the nominal SHT temperature.
Liquid–liquid interfacial tension in the monotectic alloy (Al34.5Bi65.5)95Si5 (wt.%)
Authors: Kaban Ivan , Hoyer Walter 
Published: December 2013

Abstract
The liquid–liquid interfacial tension and the density difference of the coexisting phases in the immiscible alloy (Al34.5Bi65.5)95Si5 (wt.%) have been measured between 873 and 1238 K. The interfacial tension equals (73.0 3.6) mN/m at 873 K and it decreases with increasing temperature proportionally to (1–T/TC)δ. The critical-point exponent δ=1.38, and the critical temperature TC=1410 K were determined from the experimental data.
Activity measurements on the Al-rich region of the Ni–Al system – A high temperature mass spectrometric study
Authors: Narasimhan Tiruppatur Subramaniam Lakshmi , Kath Dieter , Markus Torsten , Hilpert Klaus 
Published: December 2013

Abstract
Systematic vaporisation studies on the Ni–Al system with 0.32 x(Ni) 0.50 were carried out in the temperature range 1077–1592K by Knudsen effusion mass spectrometry. While Al(g) was the vapour species observed over all the samples, Ni(g) was also detected over samples with the compositions x(Ni)=0.50 and 0.49. From the p(Al)–T relations, activities of Al, and subsequently activities of Ni (by Gibbs–Duhem integration) were obtained. Moreover, partial and integral molar enthalpies and Gibbs energies of formation were evaluated. The variation of activities and other thermodynamic properties with composition are discussed. The enthalpy and Gibbs energy of formation of Ni0.5Al0.5(s) at 298.15K were obtained as = −62.1 4.2kJ mol−1 and = −57.71.2kJ mol−1, respectively. This is the first time that a systematic mass spectrometric investigation has been carried out on the aluminium rich region of Ni–Al system where the vacancy concentration in the NiAl phase can be as high as 10%.
Solid-State17O NMR studies on Yttria-stabilized zirconia
Authors: Viefhaus Tillmann , Müller Klaus 
Published: December 2013

AbstractVariable temperature17O NMR measurements, covering a temperature range from room temperature to 973K, were conducted on various samples from17O enriched yttria-stabilized zirconia for the first time. It is shown that spin-lattice (T1) relaxation exhibits a strong temperature dependence originating from the motional displacements of the oxygen ions, and which is almost independent of the actual sample constitution. In addition, large temperature effects are found for the17O NMR line widths (i.e. spin-spin relaxation) which – as the spin-lattice relaxation data – reflect the onset of the oxygen ion mobility. It is anticipated that the NMR line width effects are caused by motions on a length-scale which is different from that examined by spin-lattice relaxation.