FRENETIC
The design of innovative generation IV reactors, such as the Leadcooled Fast Reactor, requires stability and safety assessments to be performed in both operational and accidental transient conditions. These studies typically require the use of multiphysics models. The Fast REactor NEutronics/ThermalhydraulICs (FRENETIC) code has been developed since 2011 with the ambition to provide (approximate) solutions for liquid metalcooled fast reactor core design and/or safety analysis in a computationally effective (i.e. relatively fast) way, thanks to the fact that the 3D problem is solved with a simplified approach.
Reference geometry is the closed hexagonal fuel element configuration, as currently proposed for ALFRED prototype reactor within the framework of the FALCON consortium. The tool implements coupled neutronic (NE) and thermalhydraulic (TH) models.
Main outputs of the code are the TH variables and power 3D distributions in the core at selected times, together with their inlet and outlet values during the whole transient.
In the NE module, a 3D fullcore multigroup diffusion solver has been developed, based on a 3D coarsemesh nodal. A photon transport model and a decayheat model are also included.
In steady state mode, iterations are performed to compute the effective multiplication factor of the system.
In the transient mode three options are available:
 the point kinetics method
 a full discretisation of the prompt neutron balance equation and delayed neutron precursors balance equations with the onestep theta method
 the quasi static method.
The NE module can be run in standalone mode to compute neutron flux distribution for a given input temperature.
In the TH module, the hexagonal elements, described by 1D (axial) transient advection and conduction in the coolant coupled to conduction in the fuel pins, are thermally coupled (in explicit, thanks to the weak thermal coupling between assemblies) to each other in the transverse directions to obtain the fullcore evolution of the distribution of the TH variables.
Space derivatives along the axial direction are approximated by 1D linear finite elements, equivalent to central difference approximation. The set of equations for each assembly is solved implicitly in time (fully implicit or CrankNicolson schemes).
Also the TH module can be run in standalone mode to compute TH variables distribution and evolution in the core (or in a single channel) for a given power generation.
The two modules are coupled by transferring to the TH module the distribution of the power source computed by the NE module, which is the driver of the TH evolution; alternately, the temperature distribution computed by the TH module is input at each time step to the NE module in order to update the cross sections.
Research topics
Publications
2018
Fullcore coupled neutronic/thermalhydraulic modelling of the EBRII SHRT45R transient
Article
Caron, Dominic; Bonifetto, Roberto; Dulla, Sandra; Mascolino, Valerio; Ravetto, Piero; Savoldi, Laura; Valerio, Domenico; Zanino, Roberto
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
John Wiley & Sons
Vol.42 pp.17 (pp.134150) ISSN:0363907X DOI:10.1002/er.3571

New aspects in the implementation of the quasistatic method for the solution of neutron diffusion problems in the framework of a nodal method
Article
Caron, Dominic; Dulla, Sandra; Ravetto, Piero
ANNALS OF NUCLEAR ENERGY
ELSEVIER
Vol.87 pp.15 (pp.3448) ISSN:03064549 DOI:10.1016/j.anucene.2015.02.035

A fullcore coupled neutronic/thermalhydraulic code for the modeling of leadcooled nuclear fast reactors
Article
Bonifetto, Roberto; Dulla, Sandra; Ravetto, Piero; Savoldi, Laura; Zanino, Roberto
NUCLEAR ENGINEERING AND DESIGN
Elsevier
Vol.261 pp.10 (pp.8594) ISSN:00295493 DOI:10.1016/j.nucengdes.2013.03.030

FullCore Coupled Neutronic/ThermalHydraulic Model of Innovative LeadCooled Fast Reactors
Proceeding
Bonifetto, Roberto; Dulla, Sandra; Ravetto, Piero; Savoldi, Laura; Zanino, Roberto
TRANSACTIONS OF THE AMERICAN NUCLEAR SOCIETY
In: TRANSACTIONS OF THE AMERICAN NUCLEAR SOCIETY
American Nuclear Society
2012 ANS Annual Meeting (Chicago, IL (USA)) June 2428, 2012
Vol.106 pp.3 (pp.630632) ISSN:0003018X 
PROGRESS IN MULTIPHYSICS MODELING OF INNOVATIVE LEADCOOLED FAST REACTORS
Article
Bonifetto, Roberto; Dulla, Sandra; Ravetto, Piero; Savoldi, Laura; Zanino, Roberto
FUSION SCIENCE AND TECHNOLOGY
American Nuclear Society
Vol.61 pp.5 (pp.293297) ISSN:15361055 DOI:10.13182/FST12A13435
Total: 5