Modeling of OECD/NEA P2M Benchmark Cases by Means of TRANSURANUS Code

This paper presents the fuel performance simulation of two past experiments that are concerned with partial fuel melting. The activity is conducted in the framework of the Organisation for Economic Co-operation and Development/Nuclear Energy Agency Power to Melt and Maneuverability (P2M) – Second Framework for Irradiation Experiments (FIDES-II) Joint ExpErimental Programme (JEEP). The xM3 transient experiment involved uranium oxide (UO₂) fuel with a ZIRconium Low Oxidation alloy (ZIRLO) cladding base irradiated up to 27 MWd/kg U, followed a ramp test up to 70 kW/m leading to inception of melting. The High Burnup Chemistry Experiment 4 (HBC4) transient was performed according to a rapid power ramp, on a UO₂ fuel with a Zircaloy-4 cladding base irradiated up to 47 MWd/kg U. The linear heat generation rate reached 66.3 kW/m at the end of the transient leading to inception of melting and rodlet failure. Three main cases per each of the two transients were modeled with the TRANSURANUS code version 2015 in agreement with the benchmark specifications to consider uncertainty on the power during the ramping phases. The paper presents and discusses the analysis of these tests and provides an in-depth sensitivity analysis to assess the capabilities of the code as well as the effect of user choices in simulating the base irradiation and the inception of melting in light water reactor fuel rods.