Application of the BEPU methodology to assess fuel performance in dry storage

The present work shows the application of the BEPU (Best Estimate Plus Uncertainty) methodology in this field. Concretely, hydrides radial reorientation has been assessed based on stress predictions under challenging thermal conditions (400 °C) and a stress limit of 90 MPa. The computational tools used to do that are FRAPCON-3xt (best estimate) and Dakota (uncertainty analysis). The methodology has been applied to a typical PWR fuel rod highly irradiated (65 GWd/tU) at different power histories. The study performed allows concluding that both the power history and the prediction uncertainty should not be disregarded when fuel rod integrity is evaluated in dry storage. On probabilistic bases, a burnup of 60 GWd/tU is found out as an acceptable threshold even in the most challenging irradiation conditions considered.