Description: Spent nuclear fuels from foreign and domestic research and test reactors being returned to SRS are now stored with other nuclear materials in the L-basin at the Savannah River Site (SRS). Recent efforts have consolidated the fuel storage systems and L-basin has become the SRS site for water storage of spent nuclear fuels. Corrosion surveillance of coupons in this basin is being performed to provide assurance of safe storage of spent fuel. This paper describes the highlights of recent studies on these aluminum coupons after immersion for more than 7 years in L-basin. Selected coupons were metallurgically characterized to establish the existence of general corrosion and pitting. Pitting was observed on galvanically coupled samples and also on intentionally creviced coupons, thus demonstrating that localized concentration cells were formed during the exposure period. In these cases, the susceptibility to pitting was not attributed to aggressive basin water chemistry but to local condition s (crevices and galvanic coupling) that allowed the development of oxygen and/or metal ion concentration cells that produced locally aggressive waters. General corrosion was also observed on some of the coupons that had not been treated to enhance the protective oxide prior to exposure in the basin water. These observations demonstrate that, even when the basin water chemistry is rigorously controlled, localized aggressive conditions can develop. Although this demonstration does not suggest significant deterioration of the stored spent nuclear fuels, it does illustrate the potential for corrosion induced degradation and thus the importance of a routine surveillance program.
Date: September 24, 2004
Creator: Vormelker, Philip R. & Duncan, Andrew J.
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