Solution chemistry of wastes from US atomic weapons production is controlled to inhibit corrosion of carbon steel tanks used in containment and storage. The pH, nitrate ion and nitrite ion concentrations of fresh solutions are maintained within specified limits for this purpose. In the start up process for a new waste evaporator (RHLWE), non-radioactive solutions of similar chemistry will be circulated through carbon steel piping between a steel tank and the evaporator. The evaporator is fabricated from a corrosion resistant nickel base alloy. The equipment will be exposed continuously to the hot corrosive caustic solutions. Published corrosion rates for steel in pure caustic at the elevated temperatures indicate losses greater than 1.3 mm/y. Because the total test period for start up is relatively short, penetration will not occur. However, concern exists because the rust particles will probably circulate and precipitate throughout the system.
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