The present work concerns the detection and visualization of hydrogen and hydrides in unirradiated nuclear fuel claddings, focusing on the temporal development of hydrogen relocation and precipitation, plus the rearrangement of hydrides in three dimensions. The methods used are thermomechanical tests to trigger hydrogen mobility and precipitation, and neutron imaging. Hydrogen is a by-product of the fuel cladding oxidation in the hot reactor water during the operation of the fuel rods in the nuclear power plant. A part of the hydrogen is picked up into the cladding which consists of a zirconium alloy, and, exceeding the solubility limit, forms brittle hydrides which can affect the mechanical stability of the cladding. This integrity risk is of specific concern during handling and transportation of spent nuclear fuel, specifically after long term intermediate dry storage during which hydrogen relocation and hydrides accumulation can occur. Thus, the characterization of hydrides distributions is important for the safety assessment. Neutron imaging is very sensitive to detect hydrogen and hydrides with a high spatial resolution in a non-destructive way. To trigger hydrogen relocation and precipitation, we chose two approaches: (i) the hydrogen diffusion into the liner of a so-called duplex cladding, where the liner acts as a hydrogen sink, and (ii) the hydrogen diffusion in a mechanical stress field to cause hydrides reorientation. In both cases, the test material was slowly cooled down, to shift from a hydrogen diffusion to a precipitation mode. In the duplex cladding, hydrides gradually formed at the substrate-liner interface. Interrupted cooling allowed snapshots of the relocation. Competing attracting forces of precipitated hydrides and of the liner on diffusing hydrogen could be established. In the liner-free cladding, without any stress, hydrides form according to the texture, i.e., in a circumferential way. With hoop stress, hydrides are formed perpendicularly to the stress direction, in radial direction, which deteriorates the fracture toughness of the cladding. The hydrides reorientation is typically revealed by two dimensional cuts of samples using light optical microscopy or scanning electron microscopy. In the performed three-dimensional visualization, it turned out, that hydrides in different depths along the cladding tube axis do not necessarily show the same orientations as in a two-dimensional cut. In summary, the present work shows that conventional hydrides analyses may not provide the complete picture and may potentially ignore parts of the temporal development of hydrides accumulation or their three-dimensional arrangement.