  Although of primary importance in the mechanistic understanding of Zircaloy
hydriding, practically nothing is known on the transport properties of hydrogen
in zirconia. In this frame the muon, which can be considered as a light
hydrogen nuclide, can be used as an analogue and its behavior in zirconia and
Zircaloy corrosion layer may provide more insight to understand the behavior of
hydrogen in these phases. Preliminary muon spin relaxation ($\mu$SR)
measurements on several monoclinic zirconia samples, including a Zircaloy
corrosion layer, have been performed. From the observed muon depolarization
rate, the muon diffusivity in bulk monoclinic zirconia can be extracted and is
found comparable to that of recently reported proton diffusivity.
