CoreSOAR Core Degradation State-of-the Art Report Update: Conclusions [in press]

In 1991 the CSNI published the first State-of-the-Art Report on In-Vessel Core Degradation, which was updated to 1995 under the EC 3rd Framework programme. These covered phenomena, experimental programmes, material data, main modelling codes, code assessments, identification of modelling needs, and conclusions including the needs for further research. This knowledge was fundamental to such safety issues as in-vessel melt retention of the core, recovery of the core by water reflood, hydrogen generation and fission product release. In the last 20 years, there has been much progress in understanding, with major experimental series finished, e.g. the integral in-reactor Phébus FP tests, while others have many tests completed, e.g. the electrically-heated QUENCH series on reflooding degraded rod bundles, and one test using a debris bed. The small-scale PRELUDE/PEARL experiments study debris bed quench, while LIVE examines melt pool behaviour in the lower head using simulant materials. The integral severe accident modelling codes, such as MELCOR and MAAP (USA) and ASTEC (Europe), encapsulate current knowledge in a quantitative way. After two EC-funded projects on the SARNET network of excellence, continued in NUGENIA, it is timely to take stock of the vast range of knowledge and technical improvements gained in the experimental and modelling areas. The CoreSOAR project, in NUGENIA/SARNET, drew together the experience of 11 European partners to update the state of the art in core degradation, finishing at the end of 2018. The review covered knowledge of phenomena, available integral experiments, separate-effects data, modelling codes and code validation, then drawing overall conclusions and identifying needs for further research. The final report serves as a reference for current and future research programmes concerning core degradation in NUGENIA, in other EC research projects such as in Horizon2020 and for projects under the auspices of OECD/NEA/CSNI

First-principles study of a tilt grain-boundary in rutile

[[abstract]]The atomic and electronic structure of a tilt grain boundary in rutile TiO2 has been calculated in an ab initio manner. The method employs a plane-wave basis set and optimized pseudopotentials and is carried out within the local-density approximation of density-functional theory. The study focuses on the structure and energy of the ∑=15 36.9° (210)[001] tilt boundary, which is relaxed to equilibrium using a conjugate gradients iterative minimization technique. The calculations confirm the stability of a proposed atomic model for the boundary and provide some insight into its electronic structure.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Widespread white matter microstructural abnormalities in bipolar disorder: evidence from mega- and meta-analyses across 3033 individuals

Fronto-limbic white matter (WM) abnormalities are assumed to lie at the heart of the pathophysiology of bipolar disorder (BD); however, diffusion tensor imaging (DTI) studies have reported heterogeneous results and it is not clear how the clinical heterogeneity is related to the observed differences. This study aimed to identify WM abnormalities that differentiate patients with BD from healthy controls (HC) in the largest DTI dataset of patients with BD to date, collected via the ENIGMA network. We gathered individual tensor-derived regional metrics from 26 cohorts leading to a sample size of N = 3033 (1482 BD and 1551 HC). Mean fractional anisotropy (FA) from 43 regions of interest (ROI) and average whole-brain FA were entered into univariate mega- and meta-analyses to differentiate patients with BD from HC. Mega-analysis revealed significantly lower FA in patients with BD compared with HC in 29 regions, with the highest effect sizes observed within the corpus callosum (R2 = 0.041, Pcorr < 0.001) and cingulum (right: R2 = 0.041, left: R2 = 0.040, Pcorr < 0.001). Lithium medication, later onset and short disease duration were related to higher FA along multiple ROIs. Results of the meta-analysis showed similar effects. We demonstrated widespread WM abnormalities in BD and highlighted that altered WM connectivity within the corpus callosum and the cingulum are strongly associated with BD. These brain abnormalities could represent a biomarker for use in the diagnosis of BD. Interactive three-dimensional visualization of the results is available at www.enigma-viewer.org

Investigation of Aerosols Released at High Temperature from Nuclear Reactor Core Models.

Abstract not availableJRC.(EI)-Environment Institut

SARNET2 benchmark on air ingress experiments QUENCH-10, -16

International audienceThe QUENCH-10 (Q-10) and QUENCH-16 (Q-16) experiments were chosen as a SARNET2 code benchmark (SARNET2-COOL-D5.4) exercise to assess the status of modelling air ingress sequences and to compare the capabilities of the various codes used for accident analyses, specifically ATHLET-CD (GRS and RUB), ICARE-CATHARE (IRSN), MAAP (EDF), MELCOR (INRNE and PSI), SOCRAT (IBRAE), and RELAP/SCDAPSim (PSI). Both experiments addressed air ingress into an overheated core following earlier partial oxidation in steam. Q-10 was performed with extensive preoxidation, moderate/high air flow rate and high temperatures at onset of reflood (max Tpct = 2200 K), while Q-16 was performed with limited preoxidation, low air flow rate and relative low temperatures at reflood initiation (max Tpct = 1870 K). Variables relating to the major signatures (thermal response, hydrogen generation, oxide layer development, oxygen and nitrogen consumption and reflood behaviour) were compared globally and/or at selected locations. In each simulation, the same input models and assumptions are used for both experiments, differing only in respect of the boundary conditions. However, some slight idealisations were made to the assumed boundary conditions in order to avoid ambiguities in the code-to-code comparisons; in this way, it was possible to focus more easily on the key phenomena and hence make the results of the exercise more transparent. Remarks are made concerning the capability of physical modelling within the codes, description of the experiment facility and test conduct as specified in the code input, and code limitations that might warrant additional research to support model improvements, especially the modelling of nitride formation and melt oxidation. © 2014 Elsevier Ltd. All rights reserved

Behavior of Zr1%Nb Fuel Cladding under Accident Conditions

The behavior of the VVER fuel (E110) cladding under accident conditions has been investigated at the AEKI in order to study the role of oxidation and hydrogen uptake on the cladding embrittlement and to understand the phenomena that took place during the Paks-2 cleaning tank incident (2003). The test programme covered small scale tests and large scale tests with electrically heated 7-rod bundles in the CODEX (Core Degradation Experiment) facility. Since a hydrogen rich atmosphere could have been formed in the closed tank, the experiments were carried out in hydrogen-steam mixture.JRC.E.4-Nuclear fuel

New catalog on (U,PU)O2 properties for fast reactors and first measurements on irradiated and non-irradiated fuels within the ESNII + project.

International audienceThe thermal conductivity is an important parameter for the assessment of the FBR fuel thermal behavior during irradiation. In this study, the effect of burn-up on the thermal conductivity of FBR MOX fuel is investigated experimentallly. The thermal diffuvitiy of FBR fuel with a burn-up of 13 at% was measured by the laser flash technique and the thermal conductivity was deduced. It is shown that the thermal conductivity is higher than could be predicted with correlations issued from LWR UO2 and MOX results. This effect is interpreted as being due to the diffusion of fission products out of the fuel matrix, leading to the formation of the JOG

Generalizability of pharmacologic and psychotherapy trial results for late-life unipolar depression.

Despite evidence of low representativeness of clinical trial results for depression in adults, the generalizability of clinical trial results for late-life depression is unknown. This study sought to quantify the representativeness of pharmacologic and psychotherapy clinical trial results for late-life unipolar depression. Data were derived from the 2004-2005 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a nationally representative sample of 34,653 adults from the United States population. To assess the generalizability of clinical trial results for late-life depression, we applied a standard set of eligibility criteria representative of pharmacologic and psychotherapy clinical trials to all individuals aged 65 years and older in NESARC with a DSM-IV diagnosis of MDE and no lifetime history of mania/hypomania (n = 273) and in a subsample of individuals seeking help for depression (n = 78). More than four of ten respondents and about two of ten respondents would have been excluded by at least one exclusion criterion in a typical pharmacologic and psychotherapy efficacy trial, respectively. Similar results (i.e.41.1% and 25.9%, respectively) were found in the subsample of individuals seeking help for depression. Excess percentage of exclusion in typical pharmacologic studies was accounted for by the criterion "significant medical condition". We also found that populations typically included in pharmacologic and psychotherapy clinical trials for late-life unipolar depression may substantially differ. Psychotherapy trial results may be representative of most patients with late-life unipolar depression in routine clinical practice. By contrast, pharmacologic clinical trials may not be readily generalizable to community samples