Application of COCOSYS code for investigation of gas mixing in mistra test facility

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.In the case of a severe accident in a water-cooled nuclear power plant large amounts of hydrogen could be generated due to fuel claddings oxidation and released to the containment. At certain concentrations of steam air and hydrogen the hydrogen combustion could occur and challenge the structural integrity of the containment, which is a last barrier preventing from radioactive material release to the environment. Therefore, a detailed knowledge of containment thermal-hydraulics is necessary to predict the local distribution of hydrogen, steam and air inside the containment. This paper presents the experience of Lithuanian Energy Institute in simulation of the experiments performed in MISTRA test facility for the case of the International Standard Problem ISP47. The MISTRA facility is located in the Saclay center of France Atomic Energy Commissariat (CEA) and is related to the research of containment thermal-hydraulics and hydrogen safety. The MISTRA facility and its operating conditions are designed with reference to the containment conditions of a pressurized water reactor (PWR) in accident situation. The facility comprises containment inside which three condensers are set up and external circuits. Containment volume is ~100 m3, with an internal diameter of 4.25 m and a height of 7.3 m. Containment is not temperature regulated, but preheated by steam condensation and thermally insulated. The relevant physical phenomena for simulation are the following: 1)centered steam and helium (instead of hydrogen) injection in the containment; 2) pressure and temperature increase in the containment; 3) wall condensation at regulated wall temperature; and 4) flow pattern in the containment and resulting gas temperature and concentration distribution. Test sequence consisted of several transient and steady state stages, when the measurements of the gas temperature and gas concentration profiles where performed. The presented analyses were performed employing the code COCOSYS versions V2.0v2 and V2.3 developed at GRS mbH (Germany). COCOSYS is a lumped-parameter code for the comprehensive simulation of all relevant phenomena, processes and plant states during severe accidents in the containment of light water reactors. The free convection, forced convection, radiation heat transfer and condensation may be considered in the analysis. The condensation model is based on the heat and mass transfer analogy (Stefan’s law). The water and gas flows are calculated separately, i.e. different junctions have to be specified for these flows. Several zone models could be selected by the user. The EQUIL._MOD zone model assumes the perfect steam, gas and water mixture inside a zone. Each component of the mixture is in thermal equilibrium. NONEQUILIB model considers the water and gas mixture, which is not necessarily in thermal equilibrium, i.e. water and gas may have different temperatures and calculated separately in the energy balance. The experimental and analytical analyses showed that gas stratification was not observed and well-mixed atmosphere conditions were reached for the investigated case.dc201

Adverse childhood experiences, childhood relationships and associated substance use and mental health in young Europeans

Background: Adverse childhood experiences (ACEs) can increase risks of health-harming behaviours and poor health throughout life. While increases in risk may be affected by resilience resources such as supportive childhood relationships, to date few studies have explored these effects. Methods: We combined data from cross-sectional ACE studies among young adults (n = 14 661) in educational institutions in 10 European countries. Nine ACE types, childhood relationships and six health outcomes (early alcohol initiation, problem alcohol use, smoking, drug use, therapy, suicide attempt) were explored. Multivariate modelling estimated relationships between ACE counts, supportive childhood relationships and health outcomes. Results: Almost half (46.2%) of participants reported ≥1 ACE and 5.6% reported ≥4 ACEs. Risks of all outcomes increased with ACE count. In individuals with ≥4 ACEs (vs. 0 ACEs), adjusted odds ratios ranged from 2.01 (95% CIs: 1.70-2.38) for smoking to 17.68 (95% CIs: 12.93-24.17) for suicide attempt. Supportive childhood relationships were independently associated with moderating risks of smoking, problem alcohol use, therapy and suicide attempt. In those with ≥4 ACEs, adjusted proportions reporting suicide attempt reduced from 23% with low supportive childhood relationships to 13% with higher support. Equivalent reductions were 25% to 20% for therapy, 23% to 17% for problem drinking and 34% to 32% for smoking. Conclusions: ACEs are strongly associated with substance use and mental illness. Harmful relationships are moderated by resilience factors such as supportive childhood relationships. Whilst ACEs continue to affect many children, better prevention measures and interventions that enhance resilience to the life-long impacts of toxic childhood stress are required

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

Transmethylation inhibitors decrease chemotactic sensitivity and delay cell aggregation in Dictyostelium discoideum

In Dictyostelium discoideum, extracellular cyclic AMP (cAMP) induces chemotaxis and cell aggregation. Suspensions of cAMP-sensitive cells respond to a cAMP pulse with a rapid, transient increase of protein carboxyl methylation. The transmethylation inhibitors cycloleucine, L-homocysteine thiolactone, and coformycin decrease chemotactic sensitivity and delay cell aggregation when administered in concentrations which do not influence cAMP binding to cell surface receptors or the activity of total phosphodiesterase. The ability of the drugs to inhibit chemotaxis could be correlated with their capacity to convert the initial transient positive response of carboxyl methylation to cAMP into a negative one. This suggests that both protein O-methyltransferase and protein methylesterase are activated after stimulation of aggregative cells with cAMP, the net effect being a transient, positive response of methylation. In the presence of a sufficiently large dose of inhibitor, methyltransferase is inhibited, whereas methylesterase activity is much less affected, so that a transient negative response of methylation to cAMP is observed. The slow, positive response of carboxyl methylation to cAMP which occurs ca. 2.5 to 5 min after stimulus administration is not affected by inhibitors of transmethylation. These results suggest that methylation reactions are involved in the chemotactic response of D. discoideum cells to cAMP

Spatial Distribution of Precipitation in Lithuania

<p>Analysis is based on a 36-year record (1971–2006) of daily precipitation at 17 meteorological stations throughout Lithuania. The obtained data was used to investigate the spatial properties of the precipitation fields of monthly decadals (10-days). The average, minimum and maximum correlation coefficients of decadals were estimated. A spatial correlation of precipitation was created among all meteorological stations in Lithuania.</p><p>Article in Lithuanian</p

Supercritical CO2 extraction of Rosmarinus eriocalyx growing in Algeria: chemical composition and antioxidant activity of extracts and their solid plant materials

Supercritical fluid extraction using carbon dioxide (SFE-CO2) is an eco-friendly, safe and effective extraction technique used on an industrial level to obtain flavour and fragrances as well as bioactive compounds from aromatic plants. In the present work, we investigated the SFE-CO2 extracts obtained from leaves and flowers of Rosmarinus eriocalyx, an aromatic shrub growing in Algeria and used similarly to R. officinalis. The SFE-CO2 extracts were obtained from R. eriocalyx using the following parameters: extraction time 180 min (including 30 min of static extraction), pressure 45 MPa; temperature 70°C. The chemical profiles of SFE-CO2 extracts were determined by gas chromatography-mass spectrometry (GC–MS). β-Amyrin and camphor were major compounds in the leaf extract, whereas tetradecenoic and linolenic acids were abundant in the flower extract. The amounts of tocopherols in the SFE-CO2 extracts were determined by high performance liquid chromatography (HPLC) analysis. Here, α-tocopherol attained noteworthy concentrations (8839 μg/g dw). The antioxidant activity of SFE-CO2 extract, plant powder and residue after SFE-CO2 extraction was assessed using three different methods, namely ABTS, FRAP and DPPH assays. The overall activity was as follows: plant powder &gt; residue after SFE-CO2 extraction &gt; SFE-CO2 extracts. Findings showed that R. eriocalyx is a rich source of antioxidant compounds, especially the plant material, and that considerable part of polar bioactive components still remain in the solid residue after SFE-CO2 extraction. Consequently, both lipophilic SFE-CO2 extract and antioxidant-rich extraction residues may be of interest for various industrial applications

Trauma research in the Baltic countries : from political oppression to recovery

The aim of this paper is to provide an overview of traumatic stress studies from the three Baltic countries - Lithuania, Latvia, and Estonia - and reveal how specific social context contributes to the topics relevant in traumatic stress field in the region. Traumatic stress studies in the Baltic countries are closely related to the complicated history of the region. It was only since the restoration of independence of the Baltic States in the 1990s when traumatic stress studies could emerge. The start of the psychotraumatology in the Baltic States was inspired by the interest of the psychological effects of political violence. Four major topics in traumatic stress literature from the Baltic countries were identified in this article: political violence studies, epidemiology of trauma and posttraumatic stress disorder (PTSD), disaster studies, and developmental aspects of trauma. Traumatic events prevalence was reported between 70 and 75%, and PTSD prevalence range 2–7% in the Baltic countries. The interest in psychotraumatology in the Baltic countries is rising