Search results for "IMPIANTI"

Natural Convection Cooling of a Hot Vertical Wall Wet by a Falling Liquid Film

2008

Abstract The system studied is a plane channel in which one of the two vertical walls is kept at an arbitrary temperature profile and may be partially or completely wet by a falling liquid film, while the opposite wall is adiabatic. Air from the environment flows along the channel with a mass flow rate which depends on the balance between hydraulic resistances and buoyancy forces. These latter, in their turn, depend on the distribution of temperature and humidity (hence, density) along the channel and eventually on the heat and mass transferred from wall and film to the humid air. A simplified computational model of the above system was developed and applied to the prediction of relevant qu…

On the impact of the heat transfer modelling approach on the prediction of EU-DEMO WCLL breeding blanket thermal performances

2020

Abstract The Water-Cooled Lithium-Lead Breeding Blanket is a key component of a fusion power plant, in charge of ensure Tritium production, shield Vacuum Vessel and magnets and remove the heat power deposited by radiation and particles arising from plasma. The last function is fulfilled by First Wall and Breeding Zone independent cooling systems. Several layouts of BZ coolant system have been investigated in the last years to identify a configuration that might guarantee EUROFER temperature below the limit (550 °C) and good thermal-hydraulic performances (i.e. water outlet temperature of 328 °C). A research activity is conducted to study and compare different modelling approaches to simulat…

Mixed MHD convection and Tritium transport in fusion-relevant configurations

2005

Mixed MHD flow and Tritium transport were computed for a slender poloidal duct, representative of a DEMO HCLL blanket element. 2-D flow and temperature fields were computed in the duct's cross section under the assumption of parallel, fully developed flow, while Tritium concentration C was found by solving a fully 3-D problem with simplifying assumptions at the duct's ends. The spatial distribution of C depended on the intensity and direction of the forced flow. Significant peak factors were obtained if the net flow rate was so low that re-circulation occurred; C maxima were attained near the walls for upward flow, in the core region for downward flow.

An efficient proposal for the application of simulated annealing algorithms

2014

Complex nonlinear optimization problems require specific resolution techniques. These problems are often characterized by a solution space that presents many local optima. In these cases, local search algorithms, as the classical descent neighborhood search method, have a heavy drawback: the optimization algorithm generally converges towards a local minimum. To avoid getting trapped in a local minimum, the optimization algorithm must allow to accept worse solutions than the current one. Several kinds of algorithms have been ideated for this purpose and they differ for the acceptance criteria of a pejorative solution. Among such algorithms it is possible to remember the Taboo Search (TS) and…

On the nuclear response of the helium-cooled lithium lead test blanket module in ITER

2005

Abstract The helium-cooled lithium lead (HCLL) concept has been recently selected as one of the two European reference designs foreseen for the breeding blanket of a demonstration fusion reactor. In particular, within the framework of the research and development activities on this blanket line, an HCLL test blanket module (TBM) has to be designed and manufactured to be implemented in ITER. At the Department of Nuclear Engineering (DIN) of the University of Palermo, a research campaign has been carried out to investigate the nuclear response of HCLL-TBM inside ITER by a numerical approach based on the Monte Carlo method. A realistic 3D heterogeneous model of HCLL-TBM has been set-up and ins…

A study of the potential influence of frame coolant distribution on the radiation-induced damage of HCLL-TBM structural material

2008

Abstract Within the European Fusion Technology Programme, the Helium-Cooled Lithium Lead (HCLL) breeding blanket concept is one of the two EU lines to be developed for a Long Term fusion reactor, in particular with the aim of manufacturing a Test Blanket Module (TBM) to be implemented in ITER. The HCLL-TBM is foreseen to be located in an ITER equatorial port, being housed inside a steel-supporting frame, actively cooled by pressurized water. That supporting frame has been designed to house two different TBMs, providing two cavities separated by a dividing Plate 20 cm thick. As the nuclear response of HCLL-TBM might vary accordingly to the supporting frame configuration and composition, at t…

Study of the helium-cooled lithium lead test blanket module nuclear behaviour under irradiation in ITER

2009

Abstract The present paper deals with the detailed investigation of the helium-cooled lithium lead test blanket module (HCLL-TBM) nuclear behaviour under irradiation in ITER, carried out at the Department of Nuclear Engineering of the University of Palermo adopting a numerical approach based on the Monte Carlo method. A realistic 3D heterogeneous model of the HCLL-TBM was set-up and inserted into an ITER 3D semi-heterogeneous model that realistically simulates the reactor lay-out up to the cryostat. A Gaussian-shaped neutron source was adopted for the calculations. The main features of the HCLL-TBM nuclear response were assessed, paying a particular attention to the neutronic and photonic d…

MHD Free Convection in Helium-Cooled Lithium-Lead Blanket Modules for the Demonstration Fusion Reactor

2003

Integrated multi-physics design tool for fusion breeding blanket systems - development and validation

2020

Il Breeding Blanket (BB) del reattore DEMO rappresenta un sistema complesso in un ambiente pericoloso. Infatti, esso deve soddisfare diversi requisiti e vincoli ingegneristici sia di tipo nucleare, termo-strutturale che di sicurezza. Per questi motivi, è necessaria una progettazione omnicomprensiva che preveda l'applicazione di strumenti avanzati di simulazione basati su approcci multi-fisici. Questi strumenti devono eseguire simultaneamente diversi tipi di analisi. Tre di esse possono essere considerate prioritarie e propedeutiche per lo studio di tutti gli altri fenomeni riguardanti il BB, vale a dire l´analisi nucleare, termo-fluidodinamica e strutturale. In questa tesi, è proposto un in…

THERMOFLUID-DYNAMICS OF DEMO DIVERTOR CASSETTE

2023

The divertor is a critical in-vessel component of nuclear fusion reactors, being responsible for the fulfilment of certain fundamental functions for the machine: it must be able to handle the power deposited by charged particle and neutron irradiation, ensure the presence of channels through which the fusion ashes can be removed from the Vacuum Vessel (VV), provide plasma-compatible surfaces, and shield the VV and magnets from nuclear loads. The heat load that can be tolerated by the divertor under normal and off-normal operating conditions is a pivotal parameter when dimensioning a fusion power plant since exceptionally high heat fluxes can be observed in some regions of the divertor, in t…