Corrosion phenomena of zircaloy-2 and zircaloy-4 in nacl solution medium by electrochemically

Zircaloy-2 and zircaloy-4 are used as cladding material in Light Water Reactor, (LWR), Boiling Water Reactor (BWR) and Pressurized Water Reactor (PWR). During its use in the spent fuel pool may interact between the cladding and seawater in case of abnormal condition. Chloride ion which contained in seawater has the potential for being corrosion in cladding material. The aim of this work was knowing zircaloy-2 and zircaloy-4 corrosion phenomena in NaCl medium by corrosion parameter determination with polarization resistance technique, tafel, and potentiodynamic. Samples are zircaloy-2 and zircaloy-4 pieces material with 1x1 cm dimension. The samples are mounting and soldered with copper wire, then the sample surface are polished by 1200 grade grinding paper. Corrosion test was done with corrosion cell that was completed by electrode standard (saturated calomel), electrode buffer (graffiti) and work electrode (sample). Solvent medium was NaCl solution with concentration 3.5 %; 0.35 %; and 0.175 %. The result showed that ion CΓ contained in NaCl which were concentration area from 0.175 % to 3.5 % did not affect corrosion mechanism. The corrosion type in potential range ± 250 mV to E_corr was uniform corrosion in ZrO₂ oxide form. Zircaloy-2 and zircaloy-4 corrosion rate in 3.5 % NaCl concentration were obtained 6.39×10^-3 and 7.40×10^-3 mpy respectively. Corrosion phenomenon which was observed by potentiodynamic technique (± 1000 mV to E_corr) showed that zircaloy-2 and zircaloy-4 underwent passivation and pitting corrosion. Pitting potential zircaloy-2 and zircaloy-4 were obtained -452.8 mV and -182.8 mV severally. (author)