ELECTROCHEMISTRY CORROSION STUDY FOR TANK 241-AY-102 SLUDGE

摘要

The chemistry (sodium hydroxide and sodium nitrate concentrations) in the sludge region of the Hanford underground radioactive waste storage tank 241-AY-102, did not meet the requirements for corrosion control established in Technical Safety Requirements (TSR), Administrative Control (AC) 5.15, "Chemistry Control Program." Because there are no near-term alternatives available to correct the sludge chemistry, an understanding of the corrosion behavior of the waste in the sludge region of the tank was required. The sludge resides deep within the tank (at 60 deg Celsius) where its oxygen content may be low enough to significantly retard any corrosion mechanisms occurring at the tank wall. The requirements were to extrude a core segment sample under anaerobic conditions into an electrochemical test cell. To then perform potentiodynamic scans at 60 deg Celsius while minimizing sample handling and exposure to the atmosphere. Both the electrochemical test cell and the extrusion platform were designed and fabricated to ensure the sample maintain anaerobic integrity. The electrochemical cell was benchmarked against the ASTM G5-94 method both in a non radioactive and a radioactive hot cell environment.