High-level nuclear wastes at the Hanford Site are stored underground in carbon steel double-shell and single-shell tanks. The installation of a prototype corrosion monitoring system into double-shell tank 241-AZ-101 was completed irr August, 1996. The system monitors fluctuations in corrosion current an potential
(electrochemical noise) occurring on three electrode arrays immersed in the waste liquid and in the vapor space above the waste. The system also supports the use of Tafel and linear polarization resistance testing. By monitoring and analyzing the data from these techniques, changes in the corrosive characteristics nf the waste have been rapidly detected and correlated with operational changes in the tank.
Keywords: electrochemical noise, pitting, stress corrosion cracking, Iocalized corrosion, nuclear waste tank corrosion, mild steel,
nitrates, corrosion surveillance, and corrosion-monitoring.