Modelling of the H2020 INSPYRE Fuel Creep Experiment

To better understand irradiation creep of nuclear fuel, NRG has prepared, as part of the H2020 European project INSPYRE, a separate effect irradiation experiment in the High Flux Reactor (HFR) in Petten (the Netherlands) aiming to measure fuel creep in-pile as a function of temperature, flux, burn-up and axial pressure load. This continuous type of measurement will supply a large data set, leading to more detailed knowledge on fuel behaviour during irradiation. To support the experiment and make optimal use of the generated data, a model is created of the experiment to better predict the behaviour of the fuel samples during irradiation. The current paper describes the numerical model, which couples the 1.5D fuel performance code TRANSURANUS (TU) with a Finite Element Analysis (FEA). The thermal analysis of the experiment is carried out using the FEA. Such approach enables to model a rather complex geometry of the experiment, and to include axial heat transport, which is not implemented in TU. TU is modified in order to use the fuel pellet temperatures obtained using the FEA and to include the axial load present in the experiment. The model is validated against several test cases and used to predict the fuel behaviour during a selection of foreseen irradiation scenario’s. Results of the model will be used in the future for optimization of the irradiation parameters used in the experiment and for analysis of the data obtained during the irradiation.