FONESYS (Forum & Network of SYS-TH Codes in Nuclear Reactor Thermal-Hydraulics) is a Network for cooperation among developers of system thermal-hydraulics codes adopted worldwide for nuclear reactor analysis.

Network connects Institutions and Organizations that are involved in the development and the application of SYS-TH codes to support the Best Estimate Plus Uncertainty safety assessment and the design of water-cooled nuclear reactor.

Network has been created to strengthen the current technology, cooperate and share recent advances, identify and discuss further ways of improvements in SYS-TH code development.

The San Piero a Grado Nuclear Research Group (GRNSPG) of the University of Pisa serves as Host Institution for FONESYS.