Hanford site waste tanks concentrations

The most important consideration in tank design is minimization of corrosion. Originally two storage philosophies were believed to be equally safe in this respect (1) neutralized waste in mild steel tanks and (2) acid waste in stainless steel tanks. Almost three decades of experience have proved that only the latter satisfies all safety requirements. No leakage from stainless steel tanks has become known, whereas 20 out of 183 mild steel tanks at the Hanford and Savannah River sites developed leaks [L2]. It is now generally accepted that a minimum conosion rate can be maintained with suitable types of stainless steel and nitric acid concentrations in the range of 2 to 4 Af. If the HNO3 concentration falls below 1 M stress corrosion due to chloride ions may be promoted. 

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