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Research - Presentation

The R&D activities of the Nuclear Reactors Group refer to 5 main fields, currently applied to 3 main reactor concepts declined in international projects:

 

 

 

Thermal Fluid Dynamics:


» theoretical and experimental investigation of helical coil tube, modular steam generators, to identify the dynamic behaviour and the effect of geometrical and T-H parameters on two-phase pressure drops, dry-out, flow instability, also to obtain general validity correlations and stability maps;

 

» theoretical and experimental investigation of two-phase flow, natural circulation, closed loop passive safety systems in sliding pressure configuration, for stable-unstable behaviour characterization;

 

Experim.facility @ SIET lab: helical coil steam generator

 

 Simulation & Control, Multiphysics:

» multi-physics approach to the modelling of core neutronics, fluid dynamics and thermal mechanics features of new generation reactors (Lead-cooled and Molten Salt reactors), by developing code and routines in a single environment (COMSOL);

 

» development of object-oriented modelling for flexible and fast running simulators, for dynamic response analysis and control purposes, applicable to different reactor concepts (IRIS, reactors for space applications, ADS), adopting a model-based, predictive control strategy.

 

 

 

Multi-Physics simulation of Molten Salt Reactor: neutronics + fluid dynamics

 

 Economics:

» development of a simulation code (INCAS - INtegrated model for the Competitiveness Analysis of Small-medium sized reactors) for the analysis of economics and financial features of Small-Medium reactors (IAEA Coordinated Research Project), by modelling generation and financial costs, including external factors evaluation;

 

» comparison of Large Reactors vs. Small-Medium Modular Reactors and evaluation of deployment scenarios, for policy management decision
(a joint collaboration with POLIMI-Department of Management, Economics and Industrial Engineering).

 

 Safety:

 

» collaboration to the study, design and future operation of an integral facility (SPES-3) for the IRIS integral testing, for licensing purposes;

 

»  study of passive safety systems for new generation reactors

 

» development of a risk-informed approach and procedure to the design phase of new generation reactors (e.g. IRIS), following a “safety-by-design” strategy, the main goals obtained being a sensible reduction of both the estimated Core Damage Frequency (CDF) and the Emergency Planning Zone (EPZ).

 

 SPES-3 facility (click to enlarge)

 

 Fuel Cycle and Performance & Thermalmechanics:

» Characterization and performance of innovative fuel and cladding materials, including MOX fuels for LWRs and LFRs, T91 and other materials for Gen IV (Lead-Cooled) reactors, also by means of TRANSURANUS code simulation and ad hoc routines development;

 

» development of parametric analysis for optimal core configurations (breeder or burner) and fuel burn-up, for Gen IV reactors (Lead-cooled and Molten Salt reactors).

 

» theoretical and numerical investigation on the collapse of thick tubes under external pressure, aimed at reducing their thickness with respect to existing requirements, so as to diminish the resistance given by conductivity through the metal (interaction with ASME Boiler and Pressure Vessel Code committees);

 

» numerical analysis of the response of Nuclear Power Plants to seismic excitation, aimed at:
   (i) the definition of a simplified but accurate model to predict the acceleration history at the components supports, so as to reduce safety factors referring to analysis uncertainties;
   (ii) the assessment of soil damping influence on the component response, in order to obtain a precise definition of its effects;
   (iii) the definition of fragility curves for significant components, giving their probabilities of failure as function of the peak ground acceleration, also to the purpose of providing hints for a safer design.