A mechanistic understanding of hydrogen diffusion and hydride precipitation at the microscale underpins the
prediction of delayed hydride cracking in zirconium alloy nuclear fuel cladding. We present a novel approach to
modelling the microstructures created by hydride precipitation at loaded notches in polycrystalline Zr alloys. The
model is multi-scale in that it includes the elastic dipole tensor of interstitial hydrogen in α-Zr, it treats the stressdriven diffusion of hydrogen at the meso-level (mm), it calculates the thermodynamically favourable spatial
arrangement of microhydrides and their assembly into macrohydride colonies, in a textured polycrystalline
sample, and it treats the full elastic field of the loaded notch and all the hydrides at a scale similar to the cladding
thickness. A simplifying innovation is the representation of the elastic field of a microhydride by a dislocation
dipole, where the Burgers vector is set to create the experimentally measured strain in the 〈1100〉 direction. The
model provides a predictive framework for treating elastic anisotropy, a variety of potential nucleation sites, and
different grain sizes. Simulated micrographs of hydride networks in polycrystalline samples with blunt and
sharper loaded notches are compared with experimental micrographs obtained at the same scale. The simulations
are extremely fast and calculations typically take around tens of seconds. This makes it possible to carry out
detailed sensitivity studies with respect to several pertinent metallurgical variables, as well as conducting
ensemble averaging of hydride microstructures.