The corrosion behavior of hafnium in high-temperature water environments

The high-temperature water corrosion performance of hafnium is evaluated. Corrosion kinetic data are used to develop correlations that are a function of time and temperature. The evaluation is based on corrosion tests conducted in out-of-pile autoclaves and in out-of-flux locations of the Advanced Test Reactor at temperatures ranging from 288 to 360 °C. Similar to the corrosion behavior of unalloyed zirconium, the high-temperature water corrosion response of hafnium exhibits three corrosion regimes: pretransition, post-transition, and spalling. In the pretransition regime, cubic corrosion kinetics are exhibited, whereas in the post-transition regime, linear corrosion kinetics are exhibited. Because of the scatter in the spalling regime data, it is not reasonable to use a best fit of the data to describe spalling regime corrosion. Data are presented to show that in the pretransition regime, neutron irradiation does not alter the corrosion performance of hafnium.