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Re-examination of the fuel burnup level of the TRIGA RC-1 Casaccia reactor
No full textQuesto lavoro è stato concepito e svolto nell'ambito delle attività residuali del programma TRADE. Il programma TRADE, previsto nel reattore TRIGA RC-1 del Centro ENEA della Casaccia, era finalizzato allo studio del comportamento statico e dinamico di un ADS a potenza. Il programma fu interrotto al termine del 2004 a causa di problemi finanziari. A dispetto di tali circostanze, durante il periodo precedente l'interruzione del programma è stata generata una vasta banca dati sperimentale.
Nel 2007 la IAEA ha rivalutato tale banca dati ed ha lanciato un benchmark internazionale in seno al Coordinated Research Project "Analytical and Experimental Benchmark Analyses of Accelerator Driven Systems (ADS)" coordinato dalla stessa IAEA (2006-2010). Il benchmark, denominato "pre-TRADE experimental benchmark", è stato coordinato da ENEA. Una questione chiave per il benchmark è risultata essere il grado di conoscenza del livello di burnup del combustibile del TRIGA RC-1, ed in tale ottica è stato svolto il presente lavoro con la finalità di consentire un piccolo passo in avanti nel settore.This work was conceived and performed in the frame of the residual activities concerning the TRADE program The TRADE program, which was foreseen in RC-1 TRIGA reactor located at ENEA-Casaccia research centre near Rome, was planned to investigate the static and dynamic behaviour of ADS at power in thermal neutron spectrum. Because problems in financial backing, the program was interrupted at the end of 2004. In spite of these unlucky circumstances, a huge experimental data bank has been set up during the time period prior to the program interruption.
In 2007 IAEA endorsed this experimental campaign, and an experimental benchmark was launched in the frame of the Coordinated Research Project "Analytical and Experimental Benchmark Analyses of Accelerator Driven Systems (ADS)" coordinated by IAEA (2006-2010). The benchmark, named "pre-TRADE experimental benchmark", has been coordinated by ENEA. A "basic" issue for the benchmark concerned the degree of knowledge of the fuel burnup status of the RC-1 TRIGA reactor. In this frame this work provided a small step forward for what concerns the improvement of the knowledge of the fuel burnup status of the RC- 1 TRIGA reactor
Sviluppo di un codice di cinetica spaziale di nocciolo per sistemi LFR
Full text linkThe development of a new multi-physics simulation tool is presented for the quasi-3D analysis of a lead-cooled fast reactor core with the hexagonal fuel element configuration, as currently proposed within the framework of the European project LEADER. The tool implements coupled neutronic (NE) and thermal-hydraulic (TH) models. In the NE module a 2D + 1 D full-core multi-group diffusion solver has been developed, while in the TH module the 3D problem is split in 1 D (axial) problems along each hexagonal assembly thermally coupled to each other in the transverse directions. The two modules are coupled by exchanging the power distribution (from NE to TH) and the temperature map (from TH to NE). The code is benchmarked against pure TH and pure NE analytical solutions and the results of a coupled NE/TH simulation are also presented
Analysis of experiments in TAPIRO and study of the effects of nuclear data in the simulations
Full text linkIl reattore TAPIRO è un impianto sperimentale che può fornire importanti informazioni sulla qualità dei dati nucleari utilizzati per la fisica dei reattori. In particolare, la presenza di una grande quantità di rame nel riflettore, consente di qualificare l'adeguatezza dei dati esistenti per questo materiale in varie librerie di dati di base. In questo lavoro, il codice Serpent è usato per simulare i tassi di reazione che sono stati misurati in una campagna sperimentale condotta in passato. Il confronto quantifica le differenze nei risultati ottenuti utilizzando le librerie JEFF-3.1.1 e ENDF/B-VIII.The TAPIRO reactor is an experimental facility that may provide important information on the quality of nuclear data used for reactor physics evaluations. In particular, the presence of a large quantity of copper in the reflector, allows to qualify the adequateness of the existing data for this material in various libraries. In this work, the Serpent code is used to simulate reaction rates that were measured in an experimental campaign carried out in the past. The comparison quantifies the differences in the results obtained using JEFF-3.1.1 and ENDF/B-VIII librarie
Studi di dinamica di nocciolo per reattori LFR
Full text linkObiettivo del presente rapporto congiunto ENEA-POLITECNICO di TORINO e elaborare un modello di reattore, considerando l'accoppiamento tra la parte neutronica e quell a termoidraulica, per descrivere il comportamento della dinamica di nocciolo. L'approccio usato per la neutronica e utilizzare un modello quasi-statico multigruppo. II modulo
Termoidraulico, dettagliato, tiene conto dei vari fenomeni che si instaurano nel Fuel Assembly. I due moduli di calcolo, scritti in FORTRAN, sono accoppiati tra loro dalla piattaforma TISC, che Ii richiama per l'esecuzione, scambiando opportunamente i dati. Sono riportati dei risultati ottenuti utilizzando i dati del sistema ELSY.Aim of the present report is the elaboration of a physical-mathematical model, by taking into account the Neutronic-Thermalhydraulics coupling to analyze in detail the core dynamics. The neutronic code uses a quasi-static multigroup model. The detailed Thermal-Hydraulic code is able to consider the various events happening in the Fuel Assembly.
The two calculation parts, written in FORTRAN language, are coupled each other by the TISC commercial platform, allowing the synchronization of execution and in/out exchange of separate codes data. As an example, some results obtained by ELSY project data, are showed
Esperienza GUINEVERE critica con combustibile metallico. Analisi coefficienti di correlazione con MYRRHA
Full text linkL'esperimento GUINEVERE è un programma sperimentale per lo sviluppo dei reattori ADS in relazione con le attività sui reattori veloci a piombo presentemente svolte presso il Centro SCK di Mol (Belgio). Esso è parte del 7° programma quadro del progetto FREYA dell’EURATOM. Il presente documento è focalizzato sull'analisi della rappresentatività di questo esperimento rispetto al sistema di riferimento MYRRHA, in base a simulazioni numeriche per la determinazione di quantità integrali caratteristiche (indici spettrali). L'analisi, effettuata utilizzando la metodologia GPT implementata nel codice ERANOS, è consistita nel calcolo dei coefficienti di sensibilità richiesti per la determinazione dei coefficienti di correlazione tra le quantità integrali considerati. Per ottenere tali coefficienti è stata utilizzata la matrice di dispersione BOLNA, a 15 gruppi di energia. I risultati indicano una correlazione molto buona per tutte le grandezze integrali prese in considerazione, in particolare per gli indici spettrali ad alta energia
The physical principles of the ERANOS neutronic deterministic code and its application to the LFR and VENUS-F critical cores
No full textThis work was carried out in the framework of the EU FP7 project FREYA “Fast Reactor Experiments for hYbrid Applications”. It reports the lecture held by the author during the FREYA WP5 session for training and education on February 22-26th, 2016, at the SCK•CEN Academy for nuclear science and technology in Mol (B). The main goal was to illustrate the potentiality of the ERANOS neutronic deterministic code to PhD students coming from the EU universities. At the same time, this document could be used also in ENEA for students and researchers that may be interested and/or have to be introduced to the utilisation of the code.
ERANOS (together with Monte Carlo codes) was widely utilised in the FREYA project: in the design phase of the experiments to be realised in the VENUS-F zero-power reactor (at the Belgian Nuclear Research Centre, SCK•CEN), as well as in the post-processing analyses of the experimental results. Starting from the basic physical principles of the deterministic neutronic analyses, the lecture describes the application of ERANOS to the Lead Fast Reactor (LFR) concept and to a couple of VENUS-F Critical Cores (named CC5 and CC6), assembled and experimentally characterised during FREYA. In particular, the CC6 layout was specifically designed to reproduce locally the typical spectrum of the LFR.
The main calculation procedures were briefly shown: the cell / lattice calculations providing multi-group cross-sections of the different reactor zones for full core calculations, which can be carried out with finite differences and variational nodal methods. The experimental measurements on the CC5 and CC6 cores demonstrated the accuracy of the ERANOS results, obtained with JEFF3.1 and ENDF/B6.8 nuclear data libraries. The lecture is focused on the core criticality and spectral index calculations, by pointing out at which extent the CC6 core can reproduce accurately the LFR spectrum
Specifications of the IAEA "pre-TRADE Experimental Benchmark"
No full textQuesto lavoro e stato concepito e svolto nell'ambito delle attività residuali del programma TRADE. Il programma TRADE, previsto nel reattore TRIGA RC-1 del Centro ENEA della Casaccia, era finalizzato allo studio del comportamento statico e dinamico di un ADS a potenza. Il programma fu interrotto al termine del 2004 a causa di problemi finanziari. A dispetto di tali circostanze, durante il periodo precedente l'interruzione del programma è stata generata una vasta banca dati sperimentale.
Nel 2007 la IAEA ha rivalutato tale banca dati ed ha lanciato un benchmark internazionale in seno al Coordinated Research Project "Analytical and Experimental Benchmark Analyses of Accelerator Driven Systems (ADS)" coordinato dalla stessa IAEA (2006-2010). Il benchmark descritto in questo lavoro, denominato "pre-TRADE experimental benchmark", è stato coordinato da ENEA ed è stato focalizzato sulla valutazione, tramite calcolo, dei fattori correttivi da applicare ad una selezione di risultati di misura di reattività con tecniche PNS Area-ratio e MSA per prendere in considerazione l'influenza degli effetti spazio-energetici sui dati sperimentali grezzi.This work has been conceived and performed in the frame of the residual activities concerning the TRADE program. The TRADE program, which was foreseen in RC-1 TRIGA reactor located at ENEA-Casaccia research centre near Rome, was planned to investigate the static and dynamic behaviour of ADS at power in thermal neutron spectrum. Because problems in financial backing, the program was interrupted at the end of 2004. In spite of these unlucky circumstances, a huge experimental data bank has been set up during the time period prior to the program interruption.
In 2007 IAEA endorsed this experimental campaign, and an experimental benchmark was launched in the frame of the Coordinated Research Project "Analytical and Experimental Benchmark Analyses of Accelerator Driven Systems (ADS)" coordinated by IAEA (2006-2010). The benchmark, named "pre-TRADE experimental benchmark" and described in this report, has been coordinated by ENEA and has been
focused on the evaluation, via computation, of the correction factors to be applied to the PNS Area-ratio and MSA results for the selected reactivity estimates to take into account the role of the spatial/energy effects on the rough experimental data
Experimental Results in a Variable-Pitch Wells Rotor
Full text linkSystems based on the oscillating water column (OWC) principle are often equipped with Wells turbines as power take-offs (PTOs) to convert sea-wave energy. The self-rectifying nature of the Wells turbine represents a strength for such applications, while its limited operating range, due to stall, is one of the most relevant limitations. A possible improvement lies in varying the blade stagger angle during operation as this can delay stall by reducing the incidence angle. Although the performance of variable-pitch Wells turbines has been studied in the past, their local aerodynamic performance has never been investigated before. This study addresses this important task by experimentally reconstructing the flow field along the blade height of a Wells turbine prototype, coupled to an OWC simulator, for three values of the stagger angle. The aerodynamic behavior of the Wells rotor is characterized at its inlet and outlet, showing how the interaction between adjacent blades changes due to the stagger angle. The rotor performance is evaluated and compared, providing useful information that is of general validity for similar rows of symmetric blade profiles when pitched at different stagger angles
Feasibility studies of an experimental campaign in TAPIRO devoted to the analysis of nuclear database for minor actinides
No full textIn the frame of the NEA Expert Group on Integral Experiments for Minor Actinide Management a joint collaboration between ENEA and CEA was established with the aim to study the feasibility of a MAs irradiation campaign in the TAPIRO fast neutron source research reactor, located at the ENEA Casaccia center near Rome. In particular, during the 80’s, in the frame of an agreement between ENEA and SCK/CEN Mol (Belgium), an extensive experimental neutronic characterization of the TAPIRO source reactor was carried-out. The present work describes the simulation of the TAPIRO reactor and the experimental campaign using Monte Carlo and deterministic methods. Some computational results of the model are compared and discussed, using different cross section data libraries. Due to the relevant contribution of copper to the neutronics of this system, the effects of its properties are also preliminarily analyzed. Finally, to complement the preliminary analyses on the irradiation in TAPIRO of some CEA samples, additional evaluations about the reactivity associated with the insertion of some OSMOSE and IRMM samples into different TAPIRO channels are provided
Effects of tip gap size and aspect ratio on the performance of a Wells turbine
Full text linkThe Wells turbine is one of the most suitable power take offs for oscillating water column systems, due to its simple and effective design combined to a reasonable efficiency. In recent years, a significant number of local geometry modifications have been suggested, with the promise to provide some important performance improvements. In order to achieve the full potential of this machine, these local modifications need to be applied to an optimal configuration of the machine’s global geometric parameters, such as tip clearance, blade aspect ratio, hub-to-tip ratio and solidity. The aim of this work is to provide a comprehensive experimental analysis of the effects of aspect ratio and tip clearance on the overall performance and operating range of a Wells turbine. These two effects have been accurately isolated, excluding the influence of the Reynolds’ number, thus providing a larger and more detailed set of data with respect to the ones available in the literature. An important conclusion is that the tip clearance size, which plays a dominant role, is best expressed in non-dimensional form with respect to the blade height rather than to the blade chord. With this approach, the turbine performance appears independent from the blade aspect ratio, within the ranges of parameters analyzed in this work. A lower aspect ratio, however, helps to achieve a larger operational Reynolds’ number, leading to better overall performance
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