[en] It has been reported that the effect of thermal redistribution of hydrides across the metal-oxide interface, coupled with thermal feedback on the metal-oxide interface, is a dominating factor in the accelerated oxidation in zirconium alloys cladding PWR fuel. Especially the precipitated and redistributed hydrides are known to relieve the stress imposed onto the metal / oxide interface during the waterside corrosion of zirconium alloys. Without the hydrides the stress exceeds the critical value of 3GPa which induce the tetragonal-ZrO₂ phase formation. Therefore, in this study enhanced oxidation due to the precipitated hydrides are experimentally confirmed and the stress on the interface is measured with in-situ bend test using steam beam in order to support the stress relieve hypothesis of hydride precipitates. Prior to the bend test the enhancement of zirconium oxidation due to hydride precipitates are experimentally revealed by the in-situ and intermittent weight gain measurement during the oxidation reaction. Through these measurements, it is confirmed that hydride precipitate enhances and sometimes accelerates the oxidation reaction rate and the enhancements augments with reaction temperature increase. Steam beam bend test disclose that the stress imposed onto the metal / oxide interface surely exceeds the critical 3 GPa inducing tetragonal zirconium oxide formation. In actuality, the highest stress measured in the test is 2.9 GPa with about 0.1 μm oxide thickness. It is well-known that the stress increases rapidly with the decreasing oxide thickness. In the following study, the stress relieve due to the hydride precipitation will be experimentally verified