FENOMENA KOROSI ZIRKALOY-2 DAN ZIRKALOY-4 DALAM MEDIA LARUTAN NaCl SECARA ELEKTROKIMIA

CORROSION PHENOMENA OF ZIRKALOY-2 AND ZIRKALOY-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 Pressurezid 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 (grafit) and work electrode (sample). Solvent medium was NaCl solution with concentration 3.5 %; 0.35 %; and 0.175 %. The result showed that ion Clˉ 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 Ecorr was uniform corrosion in ZrO2 oxide form. Zirkaloy-2 and zirkaloy-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 Ecorr) showed that zirkaloy-2 and zirkaloy-4 underwent passivation and pitting corrosion. Pitting potential zirkaloy-2 and zirkaloy-4 were obtained -452.8 mV and -182.8 mV severally.