Study on the formation of bulk Zr hydride and fracture behavior analysis

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This report summarizes the study on the formation of bulk Zr hydride and fracture behavior analysis.In the first part, the preparation methods for bulk Zr, Ti and Y hydride and hydrogen solid solution without defects were developed and the physicochemical and mechanical properties were measured. They have respectively unique physico-chemical properties, and that the properties for the zirconium metal and hydrides have similar properties to the titanium and yttrium metals and hydrides, since such properties for these hydrides are ruled by the electronegativity.In the second part PEC properties of oxide film of Zr-Nb alloy with or without hydrogen were studied, and the distribution of the impurity level induced by hydrogen charging was discussed. The band gap energy of all the samples was consistent with that of ZrO2 film. The terminal solid solubility of hydrogen (TSS) for pure Zr, Zr-Nb binary alloys with different Nb concentrations, and Nb added Zircaloy-4 was examined. The TSS of the a single-phase Zr-0.3Nb (Zr-0.3 wt% Nb) specimen appeared to be almost same as that of pure Zr.In the third part, the hydrogen diffusion behavior near the crack tip was simulated by FEM using ABAQUS ver.6.5. The hydrogen quickly redistributed according to the stress distribution. The hydrogen concentration at the crack tip increased more than 10 % within one second in most situations. The crack growth rate was discussed from the results.