88,731 research outputs found
‘Il diacono e il celebrante’. Giuseppe Alessi e Salvatore Aldisio: una pagina di storia siciliana attraverso la vita e l’esperienza dei due protagonisti dell’autonomia regionale
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UNCERTAINTIES ON FISSION PRODUCT RELEASE IN A LOSS-OF-COOLING SCENARIO IN A SPENT FUEL POOL WITH MELCOR 2.0
No full textAfter the events occurred in Fukushima in 2011, the vulnerability of the Spent Nuclear Fuel (SNF) stored in Spent Fuel Pools (SFPs) was highlighted, and the reliability of the SA codes predictions in SFPs questioned. The present study synthesizes the main insights gained by quantifying the uncertainties and assessing outcomes’ sensitivities of a SFP analysis. Inspired by the Unit 4 SFP of Fukushima-Daiichi, a loss-of-cooling accident was assumed with the focus on fission products release. Calculations were performed with the MELCOR code, and the uncertainty propagation was articulated through the DAKOTA statistical tool. Fifteen input uncertain parameters related to fuel rod failures, their degradation and fission products release were selected. By using several data analysis techniques, some correlations between input parameters and figures of merit were noted. As expected, Xe and Cs uncertainties were qualitatively similar, while Ru release showed its own footprints. Two outcomes of the study worth highlighting here: the relevance of a consistent choice of the input uncertainty parameters set, both number and variables, was shown to be crucial in the analysis; a thorough characterization of the FOM sensitivity will likely require more than just an individual data analysis technique
Territorio e logistica: un binomio ancora tutto da inventare
No full textLa velocità di adattamento alle situazioni è quel concetto che sta alla base del nuovo modo di fare e vivere il territorio. Esso accomuna sia gli aspetti di urgenza legati all’esigenza di trasformazione delle strutture territoriali per far sì che esse possano confrontarsi in maniera competitiva con territori che sempre di più devono aggiornare la propria immagine ed organizzazione per far fronte ai nuovi dettami e strategie imposti dalla globalizzazione, sia gli aspetti più strettamente economici e della produzione i quali, nelle sfide lanciate dalla mondializzazione dei mercati e dall’impellenza della sostenibilità - intesa nella sua accezione più ampia - risentono in maniera sempre più pressante della necessità di un aggiornamento o di una trasformazione continui
SOURCE TERM UNCERTAINTIES IN UNMITIGATED SBO SEQUENCES IN A PWR-1000: INSIGHTS FROM THE EU-MUSA PROJECT
No full textThe Management and Uncertainties of Severe Accidents (MUSA) project focused on the testing, adapting, and employing Uncertainty Quantification (UQ) and sensitivity methods for Severe Accident (SA) analysis. In collaboration with the University of Pisa, CIEMAT conducted an Uncertainty and Sensitivity Analysis (UaSA) of Source Term (ST) estimates in an unmitigated Station Black-Out (SBO) scenario involving a 3-loop Pressurized Water Reactor with Westinghouse design (PWR-W). The study employed the MELCOR 2.2 code (version 2.2.21402) in conjunction with DAKOTA 6.7 as the UQ tool. To propagate uncertainties, the Wilks' approach was employed, with random sampling of 24 selected uncertain parameters. The Figures Of Merit (FOMs) chosen for the analysis were iodine, cesium, and noble gases releases to the environment. A sensitivity analysis, based on Pearson’s and Spearman’s Correlation Coefficients (CCs), was also conducted. In relative terms, the magnitude of the ST displayed a narrow uncertainty band. The early containment failure led to most iodine released from fuel to reach the environment, with a narrow variability. Conversely, a visible uncertainty surrounded the onset time of release to the environment (approximately 5 hours), potentially influencing the implementation of Accident Management (AM) measures that might be adopted in the scenario. Although sensitivity analyses did not identify dominant variables, emphasis was placed on the relationship between the release onset time and fuel failure time (temperature controlled), as well as the subsequent diffusional release of radionuclides
Excellence Spreading Actions in NUGENIA TA2 /SARNET
No full textStatus of the different actions in the Education and Mobility programme in NUGENIA TA2/SARNE
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