Nuclear fusion is the most promising energy source, with limitless fuel, little risk for environment and population and no long-living radioactive waste. Bringing fusion energy to the market still requires a lot of research and development activities, including the design and testing of the Breeding Blanket, which is in charge of protect the vacuum vessel and the magnet, of transferring heat generated in an efficient power conversion system and of generating enough tritium to assure self-sufficiency of the reactor. The Water Cooled Lithium Lead concept relies on the liquid lithium-lead as breeder-multiplier, pressurized water as coolant and EUROFER as structural material. Water coolant flows in the channels of the first wall and in tubes, crossing the liquid PbLi of the breeding zone. The probability that the PbLi alloy and water come in contact depends on the design features the system, thus it can be minimized but not neglected. Therefore, this is a relevant safety issue to be studied from the point of view of thermo-fluid dynamics, pressure wave propagation, and chemical reaction. Research activities are ongoing at ENEA CR Brasimone to master phenomena and processes occurring during the postulated accident to enhance the predictive capability and reliability of numerical tools, as well as to qualify computer codes, such as SIMMER and RELAP5 and the procedures for their applications. Cornerstone of these activities is LIFUS5/Mod3 facility, which simulates the failure of a water-cooling channel at 15.5 MPa in the PbLi. The facility has installed instrumentation and dedicated data acquisition system at 10kHz to provide data such as pressure, temperature, hydrogen production, for code validation. This thesis work is contributing to the experimental campaign (commissioning, execution of experiments and maintenance) and on the numerical simulation of the facility, providing tools to analyze the large datasets generated at each test. Firstly, an overview of the main phenomena occurring during the postulated accidental scenario is presented, focusing mainly on the chemical interaction studies undertaken in the past and on the capability of computer codes to simulate such scenario. Then the behavior of such codes is analyzed with respect to critical flow models, which is the main driver for the scenario progression. Finally, data coming from one of the experiments are analyzed and injection line behavior is simulated with one of the codes.
La fusione nucleare rappresenta la più promettente tra le fonti energetiche, con ridotti rischi per l’ambiente e la popolazione ed assenza di rifiuti radioattivi a lunga emivita. La costruzione di un impianto commerciale richiede tuttavia grandi sforzi in ricerca e sviluppo per lo sviluppo dei suoi componenti, tra cui il Breeding Blanket, componente il cui scopo è schermare il Vacuum Vessel ed i magneti, trasferire il calore generato in un sistema di conversione dell’energia e produrre sufficiente trizio da assicurare l’autosufficienza del reattore. Il Water Cooled Lithium Lead è una delle proposte in studio: una lega allo stato liquido di piombo e litio circonda la camera del plasma, con il piombo che dato il suo alto Z moltiplica i neutroni ed il litio (arricchito in 6Li) che li assorbe producendo trizio. Un circuito ad acqua pressurizzata raffredda la First Wall ed il metallo liquido all’interno del Breeding Blanket, che viene poi indirizzata al sistema di conversione dell’energia. La probabilità che la lega e l’acqua entrino in contatto dipende dal design scelto per i sistemi, quindi può essere minimizzata ma non trascurata. Tale scenario deve quindi essere studiato dal punto di vista termo-fluidodinamico, della propagazione delle onde di pressione e della reazione chimica tra litio ed acqua. Numerose attività di ricerca sono in corso presso il CR Enea Brasimone per approfondire i fenomeni e processi che hanno luogo durante lo scenario incidentale, migliorando le capacità predittive e l’affidabilità di codici numerici come SIMMER-III e RELAP5/Mod3.3, per procedere poi alla loro validazione e alla stesura delle procedure per la loro applicazione. Fondamentale per tale processo è l’apparato sperimentale LIFUS5/Mod3, costruito per simulare la rottura di uno dei tubi del circuito ad acqua a 15,5 MPa all’interno della lega piombo-litio. Questo è dotato di acquisizione di dati di pressione, temperature, deformazione e produzione di idrogeno fino a 10 kHz. Questo lavoro di tesi contribuisce allo svolgimento della campagna sperimentale, con la partecipazione al condizionamento iniziale, esecuzione dei test e manutenzione dell’apparato sperimentale, l’elaborazione ed analisi dei dati sperimentali con lo sviluppo di strumenti in grado di gestire il gran numero di dati generati ad ogni test. Inoltre, è stata effettuata una analisi di letteratura sui fenomeni che hanno luogo durante lo scenario incidentale, in particolare per quanto riguarda la reazione chimica, ed una analisi della applicabilità dei codici SIMMER-III e RELAP5/Mod3.3 alla simulazione della portata critica attraverso un orifizio di piccole dimensioni.
Experimental study of PbLi water reaction in LIFUS5/Mod3 facility
CRUGNOLA, RICCARDO MARIA
2018/2019
Abstract
Nuclear fusion is the most promising energy source, with limitless fuel, little risk for environment and population and no long-living radioactive waste. Bringing fusion energy to the market still requires a lot of research and development activities, including the design and testing of the Breeding Blanket, which is in charge of protect the vacuum vessel and the magnet, of transferring heat generated in an efficient power conversion system and of generating enough tritium to assure self-sufficiency of the reactor. The Water Cooled Lithium Lead concept relies on the liquid lithium-lead as breeder-multiplier, pressurized water as coolant and EUROFER as structural material. Water coolant flows in the channels of the first wall and in tubes, crossing the liquid PbLi of the breeding zone. The probability that the PbLi alloy and water come in contact depends on the design features the system, thus it can be minimized but not neglected. Therefore, this is a relevant safety issue to be studied from the point of view of thermo-fluid dynamics, pressure wave propagation, and chemical reaction. Research activities are ongoing at ENEA CR Brasimone to master phenomena and processes occurring during the postulated accident to enhance the predictive capability and reliability of numerical tools, as well as to qualify computer codes, such as SIMMER and RELAP5 and the procedures for their applications. Cornerstone of these activities is LIFUS5/Mod3 facility, which simulates the failure of a water-cooling channel at 15.5 MPa in the PbLi. The facility has installed instrumentation and dedicated data acquisition system at 10kHz to provide data such as pressure, temperature, hydrogen production, for code validation. This thesis work is contributing to the experimental campaign (commissioning, execution of experiments and maintenance) and on the numerical simulation of the facility, providing tools to analyze the large datasets generated at each test. Firstly, an overview of the main phenomena occurring during the postulated accidental scenario is presented, focusing mainly on the chemical interaction studies undertaken in the past and on the capability of computer codes to simulate such scenario. Then the behavior of such codes is analyzed with respect to critical flow models, which is the main driver for the scenario progression. Finally, data coming from one of the experiments are analyzed and injection line behavior is simulated with one of the codes.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/148395