Abstract

The Hanford site contains approximately 55 million gallons of radioactive and chemically hazardous wastes stored in 177 carbon steel underground storage tanks, of which 149 are single-shell tanks (SSTs) and the remaining tanks are double-shell tanks (DSTs). This paper presents the results of ongoing studies on the effects of various waste chemistries on localized corrosion and SCC of one of the DSTs – 241 AY-102 (AY-102). This is the only DST to have experienced a leak of the primary tank liner. The chemistries of the waste in the annular space of AY-102 were simulated using various scenarios of evaporation and equilibration with atmospheric CO2. Additionally, the metallurgical treatments undergone by the tank during its installation were simulated. The resultant simulant chemistries and thermal treatments were used in localized corrosion and stress corrosion cracking (SCC) tests. A combination of cyclic potentiodynamic polarization and potential staircase methods indicate that the secondary tank liner is not likely to suffer from localized corrosion in simulants representing the waste present in the annular space. Similarly, crack growth rate tests do not indicate an immediate threat of SCC to the secondary tank liner.

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