Improvements in transient fuel performance modelling

VTT employs the fuel transient performance code FRAPTRAN for safety-related analyses of nuclear fuel. Within the High-burnup Upgrades in Fuel Behaviour Modelling research task (KORU), capabilities of FRAPTRAN have been improved by coupling the fuel performance code to an advanced thermal hydraulic model GENFLO. Further, the mechanical modelling in the FRAPTRAN code has been modernized by implementing a new mechanical model for the fuel rod cladding stress-strain analysis. FRAPTRAN-GENFLO and the new mechanical modelling have been successfully validated against the OECD Halden Project LOCA experiments