1,721,080 research outputs found
Preliminary Thermohydraulics Design of the LORELEI Device with CATHARE
Full text linkThis report has been issued within the framework of the PAR2008-09 research program of the ENEA-MSE agreement and it is one of the deliverables of the task E "Sviluppo e validazione codici di calcolo" of the work program LP2 "Reattori evolutivi". In the Jules Horowitz Reactor (JHR) experimental facilities are foreseen, including the Light water One Rod Equipment for LOCA Experimental Investigations (LORELEI) device, which is dedicated to Loss Of Coolant Accident (LOCA) transient studies on a single fuel rod. In this work the thermal-hydraulic design of the LORELEI facility was developed with the code CATHARE. The objective of the work was: to define a 3D geometry of the facility; to verify the capacity of the system, under natural circulation, to remove the power generated by the fuel rod (up to 400 W/cm) and the power generated by gamma irradiation heating on the device materials. The study consisted of three main steps: definition of a 3D geometry of the facility, definition of a numerical model, development of thermo-hydraulic calculations
Pre-Test Analysis for an Experimental Campaign in the Upgraded HE-FUS3 Loop
Full text linkOn the basis of the results obtained in the 2009 experimental campaign conducted in the HE-FUS3 loop (CR BRASIMONE) within the framework of the first year of the AdP ENEA-MSE a new experimental campaign has been planned for the second year for the following reasons: - the post-tests calculations performed with the RELAP5 code showed for some tests a lack of important information on the facility behaviour in transient conditions that would require the repetition of the tests with an upgraded instrumentation, - new experimental tests conducted at higher pressure and mass flowrate considering previous and additional transient scenarios would allow to enlarge the experimental data base for the assessment of thermal-hydraulic codes used for HTR and VHTR design and safety analysis As for the previous year the definition of the test matrix has been supported with pre-test calculations carried out with the T/H system code RELAP5. To this purpose the HE-FUS3 model assessed in the post-test activity has been used with minor modifications
Engineering validation and engineering design of lithium target facility in Ifmif/Eveda project
No full textEVEDA Lithium Test Loop (ELTL) has been designed and constructed, has operated a liquid lithium flow test facility with the world's highest flow rate and has succeeded in generating a 100-mm-wide and 25-mmthick free-surface lithium flow along a concave back plate steadily at a high speed of 20 m/s at 300°C for the first time in the world. This result will greatly advance the development of an accelerator-based neutron source to high energy and high density, one of the key objectives of the fusion reactor materials development under the BA (Broader Approach) Activities. Recent related engineering validation and engineering design of the lithium facility has been evaluated
Nuclear assessment of the IFMIF-DONES lithium target system
No full textIn the framework of the Work Package Early Neutron Source (WPENS) of the EUROfusion Consortium, the engineering design of the IFMIF-DONES (International Fusion Material Irradiation Facility - Demo Oriented Neutron Source) lithium target system has been accomplished. The development of the design required that new neutronic calculations had to be performed in ENEA, in order to update those already achieved in the past for the previous geometrical layout. The aim of these evaluations is to provide quantities, such as power deposition, dpa and gas production, useful for the thermo-mechanical analysis that is required for assessing the structural behavior of the system subjected to irradiation. Coupled neutron-gamma transport calculations have been carried out by using the MCNP6.2 code integrated with the McDeLicious-17 neutron source. The geometrical input for MCNP used in the calculations was provided by KIT. Neutron activation calculations have been also performed by means of the FISPACT-II activation code package in order to provide radioactive quantities, such as decay heat and contact dose rates, in various parts of the system, useful for thermo-mechanical analysis and safety purposes, like waste management considerations. This paper presents the main results obtained from the above analyses
Analysis of Thermal-Hydraulic Performance of IRIS/SPES3 EHRS Condenser with an Appropriate RELAP5 Model
No full textThe numerical analysis to asses the design of the IRIS/SPES3 EIHRS condenser has been carried out with the reference RELAP code. The RELAP code has shown an inaccuracy to predict the calculation of heat power exchange and HTCs evaluation on condenser exchanger with vertical pipes. This was put in evidence in the post-test calculation of PERSEO facility in which a tuning process on heated hydraulic diameter on condensation side was utilized, being this one the bottleneck of heat conduction train, in the order to match the experimental values of exchanged power. However this procedure brought to unrealistic HTCs values. In this work, instead of the variation of heated hydraulic diameter the parameter 'Fouling Factor' has been utilized, a multiplier of HTC, which has been calibrated on the basis of CATHARE simulation results to obtain realistic HTC values. Also this criterion is a numerical artifice because the heat exchange correlation in RELAP remain inadequate, but the results are more realistic
Electrochemical hydrogen detection in DONES loop materials
No full textThe radiation-induced degradation of materials in fusion systems is planned to be investigated in IFMIF-DONES (International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source), where fast neutrons are produced by a reaction of deuteron-beams with a liquid lithium target. A by-product as critical impurity is hydrogen, which might affect the reliable and safe operation of the IFMIF-DONES loops. Therefore, an important issue is the measurement and control of the hydrogen impurity concentrations in liquid lithium. Initially, a practically applicable direct measurement of hydrogen concentrations in lithium facilities did not exist. However, one promising approach to manage this issue is based on the electrochemistry of the DONES materials The developed Electro-Chemical Hydrogen Sensor for Liquid Lithium (ECHSLL) allows the measurement of the electromotive Force (EMF) between a reference materials system and the loop lithium melt, and thus the monitoring of the hydrogen impurity concentrations. This article will show backgrounds of non-metallic impurities in liquid metal materials and the specific material stabilities within DONES. Liquid lithium is a very reactive material. Therefore critical issuesareviable materials compatibilities, the interactions with hydrogen and the transport behaviour of H-ions in electrolytes at the applied temperatures. Further issues are also the syntheses of the electrochemical materials, as hydrogen conducting electrolytes, reference electrode systems and the different procedures (heat treatments and conditioning steps). The tests showed the functionality of the developed H-sensor. Beyond that, the used material combinations exhibited reliable behaviour in melts under harsh conditions. Hence, the most critical aspect (stability of the sensor materials in the Li-melt) has been resolved by using niobium sensor heads. The observed experimental EMF potentials are in good accordance compared with calculated models, also in long-time experiments
Detection of hydrogen as impurity in liquid lithium: An electrochemical hydrogen-sensor for IFMIF-DONES
Full text linkIFMIF-DONES, the International Fusion Materials Irradiation Facility - DEMO Oriented NEutron Source, is the planned facility in Granada/Spain for fusion materials investigations using neutron irradiation in the scale of DEMO-oriented energies. This irradiation is generated by the interaction of deuteron beams with a liquid lithium flow-target system, containing huge amounts of this very reactive alkaline-metal. An important and critical issue during the operation of IFMIF-DONES is the enrichment of dissolved impurity components in the Li-melt and in the liquid melt concerning reactivity, corrosivity and radiation hazards. In the case of hydrogen, there is the danger of H-introduced embrittlement of the loop structure components as well as effects and hazards of the radioactive tritium. The application of liquid lithium in the scope IFMIF-DONES unconditionally hence requires a suitable impurity control. Regarding this subject, an electrochemical sensor for a continuous hydrogen monitoring is being developed in the frame of an international EUROFusion-WPENS task. This sensor was designed as single-rod-measuring-cell with niobium as the relevant membrane-material and a hydrogen conducting electrolyte. Potentials (Electro-Motive Force EMF) are being measured between the Li melt and a reference electrode by voltmeters with high impedances and can easily converted into H concentrations. Long-term tests (campaign-units of several hundred hours) in stagnant Li-melts with different sharply controlled hydrogen concentrations showed, that the sensor fulfills the requirements of chemical and mechanical stability and functionality also under harsher conditions (temperatures up to 500 °C). The obtained results and operational experiences will be discussed, e.g., concerning application windows, reproducibility and calibration needs. Additionally, recommendations will be outlined for upgraded systems and future qualification needs
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
Caratterizzazione cromatografica della frazione volatile e solubile di cagliate congelate
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