Extension and application of the TRANSURANUS code to the normal operating conditions of the MYRRHA reactor

•Extension of the TRANSURANUS fuel performance code to the MYRRHA pin cladding material.•Creep and void swelling modelling of DIN1.4970.•Application of TRANSURANUS to the fuel and cladding performance analysis of MYRRHA.•Simulation of MYRRHA normal operating conditions and identification of worst-case scenarios.•Assessment of the code predictions adopting conservative design limits. This work deals with the performance analysis of the MYRRHA hottest fuel pin in normal operating conditions, employing the TRANSURANUS fuel performance code, with the aim of assessing the current design specifications considering conservative design limits. To allow the proper simulation of the MYRRHA pin behaviour, TRANSURANUS is extended with novel correlations for the creep and void swelling response of the specific cladding material (DIN 1.4970). The analysis of the best-estimate reference scenario is complemented by a sensitivity analysis on models describing fuel and cladding phenomena and properties, determining those which most affect the pin performance results and identifying the worst-case scenarios. The simulation outcomes point out the high level of safety related to the MYRRHA fuel pin performance in normal operating conditions, which keeps far from any design or critical limit, even in the most challenging (worst-case) scenarios.