Behavior of the melt pool in the lower plenum of the reactor pressure vessel - review of experimental programs and background of the LIVE program

Das Verhalten eines Schmelze-Pools im unteren Plenum eines Reaktordruckbehälters – Überblick über experimentelle Programme und Grundlagen für das LIVE-Versuchsprogramm Die Rückhaltung der Kernschmelze im unteren Plenum des Reaktordruckbehälters (RDB) ist eine der in den letzten Jahren intensiv untersuchten Strategien, um einen hypothetischen Kernschmelzunfall zu beherrschen. In verschiedenen Institutionen weltweit wurden deshalb Experimente durchgeführt, um diese Strategie, welche bereits für das KKW Loviisa (Finnland) und den AP 600 (USA) genehmigt wurde, weiterzuentwickeln. Die wichtigsten Experimente waren dabei: • COPO-Experimente in Fortum Nuclear Services und CEA (Frankreich) • BALI-Experimente bei CEA (Frankreich) • SIMECO-Experimente im KTH (Schweden) • ACOPO-Experimente an der Universität von Kalifornien, Santa Barbara (USA) Diese Untersuchungen wurden nicht nur durchgeführt, um die Möglichkeit der Schmelze-Rückhaltung im RDB zu untersuchen, sondern auch, um das Verhalten eines Schmelzepools im unteren Plenum des RDB grundlegend zu verstehen. Die Ergebnisse dieser Untersuchungen wurden dazu verwendet, Modelle bzw. Korrelationen zu ermitteln, die in Rechencodeszur Untersuchung schwerer Unfälle verwendet werden können. Das Forschungszentrum Karlsruhe beteiligt sich mit der Versuchsanlage LIVE (Late In-Vessel Phase Experiments) an diesen Untersuchungen. Das Hauptziel dieses Berichtes ist es, die Ergebnisse anderer experimenteller Programme zum Schmelzeverhalten im unteren Plenum des RDB’s zusammenzufassen und damit ein Bild des derzeitigen Kenntnisstandes zu geben. Weiterhin soll gezeigt werden, wie die noch offenen Fragen im LIVE-Programm untersucht werden können

The role of learning in complex problem solving using MicroDYN

It is still an open question which cognitive and non-cognitive personality traits are useful for describing and explaining behaviour and performance in complex problems. During complex problem solving (CPS), problem solvers have to interact with the task in a way in which learning ability might be beneficial for successful task completion. By investigating the relationship between learning ability and CPS, while accounting for interactions between complex system characteristics and person characteristics, this paper aims to understand the role of learning processes in CPS more closely. In a sample of N = 241 participants, we performed a preregistered analysis to investigate the relationship between knowledge acquisition performance in a CPS test (MicroDYN) and learning test performance (ADAFI) with a multilevel modeling approach across 10 CPS systems with various characteristics. In line with our expectations, we replicated previous findings on a relationship between learning test and MicroDYN performance and found this relationship to be more pronounced in systems with (vs. without) autonomous changes. Further system and person characteristics also showed effects as expected, with better performance in systems with lower complexity, with more experience with the task, and with more strategic exploration behaviour. Our results provide further evidence for the notion that learning is an important component for the successful completion of CPS tasks

Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry

Ramsey's method of separated oscillatory fields is applied to the excitation of the cyclotron motion of short-lived ions in a Penning trap to improve the precision of their measured mass. The theoretical description of the extracted ion-cyclotron-resonance line shape is derived out and its correctness demonstrated experimentally by measuring the mass of the short-lived $^{38}$Ca nuclide with an uncertainty of $1.6\cdot 10^{-8}$ using the ISOLTRAP Penning trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter $^{38}$Ca is an important contribution for testing the conserved-vector-current hypothesis of the electroweak interaction. It is shown that the Ramsey method applied to mass measurements yields a statistical uncertainty similar to that obtained by the conventional technique ten times faster.Comment: 5 pages, 4 figures, 0 table

A balancing act: Evidence for a strong subdominant d-wave pairing channel in Ba0.6K0.4Fe2As2{\rm Ba_{0.6}K_{0.4}Fe_2As_2}

We present an analysis of the Raman spectra of optimally doped ${\rm Ba_{0.6}K_{0.4}Fe_2As_2}$ based on LDA band structure calculations and the subsequent estimation of effective Raman vertices. Experimentally a narrow, emergent mode appears in the $B_{1g}$ ($d_{x^2-y^2}$) Raman spectra only below $T_c$, well into the superconducting state and at an energy below twice the energy gap on the electron Fermi surface sheets. The Raman spectra can be reproduced quantitatively with estimates for the magnitude and momentum space structure of the s$_{+-}$ pairing gap on different Fermi surface sheets, as well as the identification of the emergent sharp feature as a Bardasis-Schrieffer exciton, formed as a Cooper pair bound state in a subdominant $d_{x^2-y^2}$ channel. The binding energy of the exciton relative to the gap edge shows that the coupling strength in this subdominant $d_{x^2-y^2}$ channel is as strong as 60% of that in the dominant $s_{+-}$ channel. This result suggests that $d_{x^2-y^2}$ may be the dominant pairing symmetry in Fe-based sperconductors which lack central hole bands.Comment: 10 pages, 6 Figure

Follow-up investigations of tau protein and S-100B levels in cerebrospinal fluid of patients with Creutzfeldt-Jakob disease

Background: S-100B and tau protein have a high differential diagnostic potential for the diagnosis of Creutzfeldt-Jakob disease (CJD). So far there has been only limited information available about the dynamics of these parameters in the cerebrospinal fluid (CSF). However, there is a special interest in finding biochemical markers to monitor disease progression for differential diagnosis and treatment. Patients and Methods: We analyzed CSF of 45 patients with CJD and of 45 patients with other neurological diseases for tau protein and S-100B in a follow-up setting. All diagnoses of CJD were later neuropathologically verified. A ratio between tau protein differences and the time between lumbar puncture was calculated. The same was done for S-100B. Results: Tau protein levels of 34 cases were above the cut-off level for CJD (>1,300 pg/ml) in the first CSF sample. In 7 of 11 patients with lower tau levels in the first CSF sample, tau levels rose. The above-mentioned ratio was significantly higher in the CJD group than in the group with other neurological diseases. Similar results were obtained for S-100B. Conclusion: We conclude that follow-up investigations and calculation of ratios is a useful tool in the differential diagnosis of CJD. Variations in this pattern were observed in single cases. Copyright (C) 2005 S. Karger AG, Basel

Which solar EUV indices are best for reconstructing the solar EUV irradiance ?

The solar EUV irradiance is of key importance for space weather. Most of the time, however, surrogate quantities such as EUV indices have to be used by lack of continuous and spectrally resolved measurements of the irradiance. The ability of such proxies to reproduce the irradiance from different solar atmospheric layers is usually investigated by comparing patterns of temporal correlations. We consider instead a statistical approach. The TIMED/SEE experiment, which has been continuously operating since Feb. 2002, allows for the first time to compare in a statistical manner the EUV spectral irradiance to five EUV proxies: the sunspot number, the f10.7, Ca K, and Mg II indices, and the He I equivalent width. Using multivariate statistical methods such as multidimensional scaling, we represent in a single graph the measure of relatedness between these indices and various strong spectral lines. The ability of each index to reproduce the EUV irradiance is discussed; it is shown why so few lines can be effectively reconstructed from them. All indices exhibit comparable performance, apart from the sunspot number, which is the least appropriate. No single index can satisfactorily describe both the level of variability on time scales beyond 27 days, and relative changes of irradiance on shorter time scales.Comment: 6 figures, to appear in Adv. Space. Re

Mitochondrial Homeostasis Mediates Lipotoxicity in the Failing Myocardium

Heart failure remains the most common cause of death in the industrialized world. In spite of new therapeutic interventions that are constantly being developed, it is still not possible to completely protect against heart failure development and progression. This shows how much more research is necessary to understand the underlying mechanisms of this process. In this review, we give a detailed overview of the contribution of impaired mitochondrial dynamics and energy homeostasis during heart failure progression. In particular, we focus on the regulation of fatty acid metabolism and the effects of fatty acid accumulation on mitochondrial structural and functional homeostasis

The LYRA Instrument Onboard PROBA2: Description and In-Flight Performance

The Large Yield Radiometer (LYRA) is an XUV-EUV-MUV (soft X-ray to mid-ultraviolet) solar radiometer onboard the European Space Agency PROBA2 mission that was launched in November 2009. LYRA acquires solar irradiance measurements at a high cadence (nominally 20 Hz) in four broad spectral channels, from soft X-ray to MUV, that have been chosen for their relevance to solar physics, space weather and aeronomy. In this article, we briefly review the design of the instrument, give an overview of the data products distributed through the instrument website, and describe the way that data are calibrated. We also briefly present a summary of the main fields of research currently under investigation by the LYRA consortium

Fast calculation of real fluid properties for steam turbine CFD analysis with the new IAPWS standard on the spline-based table look-Up method (SBTL)

Workshop byl částečně podpořen projektem CZ.1.07/2.3.00/20.0139. Tento projekt je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky