Electrochemical behaviour and hydride embrittlement evaluation of titanium during cathodic polarization in HNO3/UO/N2H solutions

In conjunction with reprocessing of nuclear fuels by electrochemical methods, the general electrochemical behaviour of titanium cathodes and the problem of their hydride embrittlement have been investigated in the absence of γ-radiation in HNO₃/UO/N₂H solutions of varying composition. The electrode potential of galvanostatically polarized titanium cathodes is shown to be located either in the passive range, within the passive-to-active transition, or in the regime of hydrogen absorption/hydride formation, depending on the current yield of the nitrate reduction reaction. Hydride growth was observed predominantly in the morphology of continuous layers and/or isolated platelets. Following a parabolic rate law it was restricted to the vicinity of the electrode surface, the maximum penetration for polarization times up to 1000 h being less than 100 μm. As a consequence, no significant loss of ductility of normal tensile specimens could be detected under these conditions.