1,721,250 research outputs found
Micro-channel-based high specific power lithium target
No full textA micro-channel.based heat sink has been produced and tested. The device has been developed to be used as a Lithium target for the LENOS (Legnaro Neutron Source) facility and for the production of radioisotope. Nevertheless, applications of such device can span on many areas: cooling of electronic devices, diode laser array, automotive applications etc. The target has been tested using a proton beam of 2.8MeV energy and delivering total power shots from 100W to 1500W with beam spots varying from 5mm2 to 19mm2. Since the target has been designed to be used with a thin deposit of lithium and since lithium is a low-melting-point material, we have measured that, for such application, a specific power of about 3kW/cm2 can be delivered to the target, keeping the maximum surface temperature not exceeding 150 °C
ELSY—European LFR Activities
No full textThe European Lead Fast Reactor has been developed in the frame of the European lead system (ELSY) project funded by the Sixth Framework Programme of EURATOM. The project, coordinated by Ansaldo Nucleare, involved a wide consortium of European organizations. The ELSY reference design is a 600MWe pool-type reactor cooled by pure lead. The project demonstrates the possibility of designing a competitive and safe fast critical reactor using simple engineered technical features, whilst fully complying with the Generation IV goals. The paper focuses on the main aspects of the proposed design for the European lead fast reactor highlighting the innovation of this reactor concept and overall objectives. Special attention has been dedicated to safety starting from the first step of the design development taking into account other important aspects, such as the investment protection, the compactness of the primary system as well as sustainability. The main safety features of the proposed innovative decay heat removal (DHR) systems are presented. From the beginning of 2010, and for a duration of three years, the European Commission (EC) is financing the new project Lead European Advanced Demonstration Reactor (LEADER) as part of the 7th Framework Program. This paper highlights the main objectives of the LEADER project. © 2011 Atomic Energy Society of Japan. All Rights Reserved
Developing structural, high-heat flux and plasma facing materials for a near-term DEMO fusion power plant: The EU assessment
No full textThe findings of the EU 'Materials Assessment Group' (MAG), within the 2012 EU Fusion Roadmap exercise, are discussed. MAG analysed the technological readiness of structural, plasma facing and high heat flux materials for a DEMO concept to be constructed in the early 2030s, proposing a coherent strategy for R&D up to a DEMO construction decision. A DEMO phase I with a 'Starter Blanket' and 'Starter Divertor' is foreseen: the blanket being capable of withstanding ≥2 MW yr m-2 fusion neutron fluence (∼20 dpa in the front-wall steel). A second phase ensues for DEMO with ≥5 MW yr m -2 first wall neutron fluence. Technical consequences for the materials required and the development, testing and modelling programmes, are analysed using: a systems engineering approach, considering reactor operational cycles, efficient maintenance and inspection requirements, and interaction with functional materials/coolants; and a project-based risk analysis, with R&D to mitigate risks from material shortcomings including development of specific risk mitigation materials. The DEMO balance of plant constrains the blanket and divertor coolants to remain unchanged between the two phases. The blanket coolant choices (He gas or pressurised water) put technical constraints on the blanket steels, either to have high strength at higher temperatures than current baseline variants (above 650 °C for high thermodynamic efficiency from He-gas coolant), or superior radiation-embrittlement properties at lower temperatures (∼290-320 °C), for construction of water-cooled blankets. Risk mitigation proposed would develop these options in parallel, and computational and modelling techniques to shorten the cycle-time of new steel development will be important to achieve tight R&D timescales. The superior power handling of a water-cooled divertor target suggests a substructure temperature operating window (∼200-350 °C) that could be realised, as a baseline-concept, using tungsten on a copper-alloy substructure. The difficulty of establishing design codes for brittle tungsten puts great urgency on the development of a range of advanced ductile or strengthened tungsten and copper compounds. Lessons learned from Fission reactor material development have been included, especially in safety and licensing, fabrication/joining techniques and designing for in-vessel inspection. The technical basis of using the ITER licensing experience to refine the issues in nuclear testing of materials is discussed. Testing with 14 MeV neutrons is essential to Fusion Materials development, and the Roadmap requires acquisition of ≥30 dpa (steels) 14 MeV test data by 2026. The value and limits of pre-screening testing with fission neutrons on isotopically- or chemically-doped steels and with ion-beams are evaluated to help determine the minimum14 MeV testing programme requirements. © 2014 The Authors. Published by Elsevier B.V. All rights reserved
Optical classification, existence temperatures, and coexistence of different polar stratospheric cloud types
No full textMultispectral lidar measurements of polar stratospheric clouds (PSCs) from two winter campaigns in 1994/1995 and 1996/1997 at Sodankylä, Finland, have been evaluated together with temperature data from local radiosondes to find optical parameters for a PSC classification of different particle types and their existence temperatures. Precise depolarization measurements show that both solid and liquid particles exist below the NAT (nitric acid trihydrate) temperature. A comparison of temperatures at the PSC base and at the cloud top shows a good agreement with the NAT-existence temperature for solid type Ia clouds and a 3-4 K lower temperature for liquid type Ib clouds. The two particle families are therefore consistent with solid NAT particle formation and condensational growth of HNO3, H2O and H2SO4 liquid ternary solutions. The coexistence of solid and liquid particles has been observed by means of the temporal development of parallel and perpendicular polarized lidar signals. These time series of subsequent lidar measurements show stronger and faster fluctuations in the liquid particle mode compared to the solid particles and thus indicate a higher sensitivity toward temperature fluctuations for the liquid PSCs. While the optical properties of most observations are consistent with the definition of PSC type Ia (solid) and type Ib (liquid) clouds, a third type has been observed which does not fit into the current type Ia/Ib optical classification. This cloud type consists of solid particles but has a higher backscatter than type Ia PSC. Copyright 1999 by the American Geophysical Union
Using multiple indices to evaluate scenarios for the remediation of contaminated land: the Porto Marghera (Venice, Italy) contaminated site
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
NUCLEARE DA FISSIONE: STATO E PROSPETTIVE
Full text linkQuesto documento è stato redatto dal Comitato di Coordinamento sul nucleare da fissione e da altri colleghi ENEA esperti nel settore con l'obiettivo di effettuare lo 'stato dell'arte' e analizzare le prospettive di sviluppo del nucleare da fissione nel mondo, in Europa e in Italia. Esso vuole rappresentare solamente la base di partenza sulla quale sviluppare i necessari approfondimenti tematici, per un supporto più puntuale all'azione del Governo per il ritorno all'energia nucleare in Italia
Lead-bismuth eutectic recrystallization studies for the Megapie target
No full textThe expansion behaviour after freezing of the lead-bismuth eutectic (LBE) with 44.5% lead and 55.5% bismuth is described according to the reported theory. The issue of the vessel structural integrity after LBE recrystallization was dealt with by experimental and numerical studies performed in the frame of the Megapie (Megawatt Pilot Experiment) project. We have identified the important elements which, in the case of LBE solidification inside the Megapie target, play a role in the reduction of the possible vessel over-stressing; among them, the LBE yield strength has been tested under significant experimental conditions. The resulting suggestions can also be related to the design and to the freezing procedures for other LBE technology facilities
Estimating the small area effects of austerity measures in the UK
No full textGovernments across Europe are starting to implement a range of cost-cutting and income- generating programmes in order to re-balance their fiscal budgets following substantial investments in stabilising domestic financial institutions in 2008 and 2009. One method of doing this has been to increase tax rates such as the increase in VAT in the UK from 17.5% to 20% from January 1st 2011. In this paper we explore the different spatial impact of this VAT rise on household expenditure on public and private transport and communication technology from 2006 to 2016. We do this by combining three elements: an agent-based dynamic population microsimulation model that produces projected snapshots of the UK population in 2006, 2011 and 2016; an expenditure system model based on the familiar Quadratic Almost Ideal Demand System approach; and synthetic small area census tables produced by projecting historical UK census data. Taken together these elements provide a toolkit for assessing the potential spatial impact of rising taxes or prices (or both) and we use them to compare small area projections of household expenditure under two scenarios. The first is a 'no intervention' scenario where prices and income align to UK government inflation forecasts and the second is a one-off non-reversed 2.5% increase in VAT on goods and services rated at 17.5% on 1st January 2011. We present results for different areas (rural vs urban/deprived vs affluent) and for different income groups within them and discuss the potential implications for the telecommunications industry and for the usage of public and private transport
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