This paper summarizes the work performed by the Institute for Nuclear Research and Nuclear Energy (INRNE,
BAS) – Sofia, Bulgaria in the IAEA’s Coordinated Research Project “Fuel Modelling in Accident Conditions (FUMAC)”. The
IFA 650 LOCA experiments in Halden are integral in-pile tests on fuel behaviour under simulated LOCA conditions. Object
of the proposed analysis is the case IFA650.11 from the Halden LOCA experiments. It is a test of the fuel rod with WWER
fuel, manufactured by JSC TVEL and pre-irradiated up to 56 MWd/kgU in the Loviisa NPP (Finland). The cladding material
was Zr alloy E110. The modified version of the TRANSURANUS code with incorporated specific LOCA models as well as two
different models of thermo-hydraulic boundary conditions was applied. Fuel behaviour code predictions were analysed and
Keywords: fuel performance, LOCA, oxide layer thickness.