Dislocation density transients and saturation in irradiated zirconium

Zirconium alloys are widely used as the fuel cladding material in pressurised water reactors, accumulating a significant population of defects and dislocations from exposure to neutrons. We present interpret synchrotron microbeam X-ray diffraction measurements proton-irradiated Zircaloy-4, where we identify transient peak subsequent saturation dislocation density function exposure. This is explained by direct atomistic simulations showing that observed variation dose natural result evolution dense defect microstructure driven concurrent generation their stress-driven relaxation. In dynamic equilibrium state developing high limit, content distribution loops, coexisting with network, follows power law exponent $\alpha \approx 2.2$. corresponds $\beta 3.4$ for loops diameter compares favourably experimentally measured values $\beta$ range $ 3 \leq \beta 4$.