PROJECT DESCRIPTION
Hydride precipitation is relevant for nuclear engineering application because it causes embrittlement of the fuel cladding. This is an issue both for spent fuel or for LWRs in accident conditions (for example during a reactivity-initiated accident.
The MIMIC coupling interface has been employed to simulate hydrogen migration and hydride precipitation in a PWR fuel subassembly using the fuel behavior code BISON and the CFD code STAR-CCM+.
RESULTS
Simulations using the CFD code STAR-CCM+ have been used to simulate the temperature distribution in a PWR 5×5 subassmebly. As indicated in the figure below, highly non-uniform temperature distributions on fuel pins are found. While heterogeneous pin power distribution contributes to the non uniform temperature distribution, the strong azimuthal temperature gradients are mostly the result of the effect of the grid spacers mixing vanes.
The effect of the azimuthal temperature distribution on hydrogen migration and hydride precipitation for a selected pin (Pin 11 in the figure above) and a given elevation (also indicated in the picture above) is reported in the figure below.