ALFRED (Advanced Lead Fast Reactor European Demonstrator) is the 300 MWth pool-type reactor aimed at proving the feasibility of the design concept adopted for the European Lead-cooled Fast Reactor (LFR) of Generation IV, whose preliminary design has been proposed within the LEADER (Lead Cooled European Advanced Demonstration Reactor) EURATOM Project. An LFR-oriented version of the deterministic fuel pin performance code TRANSURANUS has been developed in the frame of a collaboration between the JRC-ITU (Joint Research Center, Institute for Transuranium Elements, Germany) and Politecnico di Milano. In the present work, all the correlations for LFR coolant and cladding implemented in this version have been reviewed. Moreover, this version of TRANSURANUS has been extended with the introduction of specific routines for the modeling of the cladding material (in particular, as concerns the thermal creep strain rate, and the thermal creep cumulative damage function, which has been based on an innovative parameter instead of the more classical Larson-Miller parameter). In the thesis, moreover, fuel pin performance analysis for the ALFRED reactor is carried out adopting this extended TRANSURANUS version. Results of the average and the hottest reactor conditions are discussed, concerning both fuel and cladding performance, on the basis of indicative design limits. A sensitivity analysis is performed in order to assess the impact of models and parameters affected by a larger uncertainty, and to identify a “worst case” scenario. This strategy allows identifying some design parameters of the pin (namely, the gap width, the internal pre-pressurization, and the upper plenum), which could be modified to improve its thermo-mechanical behavior, in order to gain benefits in terms of maximum fuel temperature. The results of the present work are useful for giving feedbacks to the conceptual design of the ALFRED reactor and, in perspective, to improve the “safety by design” characteristics of the LFR systems.
ALFRED (Advanced Lead Fast Reactor European Demonstrator) è un reattore a piscina con una potenza di 300 MWth, progettato per dimostrare la fattibilità tecnica ed economica della filiera dei reattori veloci a piombo di quarta generazione, il cui design preliminare è parte del progetto LEADER (Lead-cooled European Advanced Demonstration Reactor) finanziato da EURATOM nel settimo Programma Quadro dell’Unione Europea. Nell’ambito di una collaborazione di ricerca fra l’Istituto degli Elementi Transuranici della Commisione Europea (Karlsruhe, Germania) e il Politecnico di Milano è stata sviluppata una versione dedicata ai reattori a piombo del codice di fuel pin performance TRANSURANUS. Durante il lavoro di tesi, le correlazioni implementate in questa versione per il termovettore (piombo) e il materiale di guaina (acciaio austenitico) sono state oggetto di un’attenta revisione critica. Inoltre, sono state aggiunte nuove correlazioni per la modellazione dell’acciaio di guaina (in particolare per quanto riguarda le problematiche relative allo scorrimento viscoso), realizzando una versione estesa di TRANSURANUS. Nella tesi è stata effettuata un’analisi di performance delle barrette di combustibile di ALFRED utilizzando la succitata versione estesa di TRANSURANUS. I risultati relativi alle condizioni di reattore medie e più calde, sia per la guaina che per il combustibile, sono stati discussi in relazione ai limiti di progetto preliminari. Vista l’incertezza associata ad alcuni modelli e parametri critici, è stata effettuata un’analisi di sensitività volta alla definizione di uno scenario penalizzante per la performance. Alcuni parametri di progetto della barretta (l’ampiezza dell’intercapedine tra guaina e combustibile, la pressione interna di riempimento e l’altezza del plenum superiore) sono stati quindi modificati per ottenere una riduzione della temperatura massima del combustibile (altrimenti al di sopra dei limiti preliminari). I risultati di questo lavoro di tesi permettono di fornire indicazioni utili al progetto del reattore ALFRED e, più in generale, per migliorare la sicurezza intrinseca dei reattori a piombo.
Extension and application of a fuel pin performance code in the conceptual design of a lead cooled fast reactor
PIZZOCRI, DAVIDE
2012/2013
Abstract
ALFRED (Advanced Lead Fast Reactor European Demonstrator) is the 300 MWth pool-type reactor aimed at proving the feasibility of the design concept adopted for the European Lead-cooled Fast Reactor (LFR) of Generation IV, whose preliminary design has been proposed within the LEADER (Lead Cooled European Advanced Demonstration Reactor) EURATOM Project. An LFR-oriented version of the deterministic fuel pin performance code TRANSURANUS has been developed in the frame of a collaboration between the JRC-ITU (Joint Research Center, Institute for Transuranium Elements, Germany) and Politecnico di Milano. In the present work, all the correlations for LFR coolant and cladding implemented in this version have been reviewed. Moreover, this version of TRANSURANUS has been extended with the introduction of specific routines for the modeling of the cladding material (in particular, as concerns the thermal creep strain rate, and the thermal creep cumulative damage function, which has been based on an innovative parameter instead of the more classical Larson-Miller parameter). In the thesis, moreover, fuel pin performance analysis for the ALFRED reactor is carried out adopting this extended TRANSURANUS version. Results of the average and the hottest reactor conditions are discussed, concerning both fuel and cladding performance, on the basis of indicative design limits. A sensitivity analysis is performed in order to assess the impact of models and parameters affected by a larger uncertainty, and to identify a “worst case” scenario. This strategy allows identifying some design parameters of the pin (namely, the gap width, the internal pre-pressurization, and the upper plenum), which could be modified to improve its thermo-mechanical behavior, in order to gain benefits in terms of maximum fuel temperature. The results of the present work are useful for giving feedbacks to the conceptual design of the ALFRED reactor and, in perspective, to improve the “safety by design” characteristics of the LFR systems.| File | Dimensione | Formato | |
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2013_10_Pizzocri.pdf
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Descrizione: Testo della tesi
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https://hdl.handle.net/10589/85161