• Gray, J.
• Wiersma, B.

Abstract

Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 70 years at theHanford nuclear facility. Vapor space corrosion of the tank walls has emerged as an ongoing challenge toovercome in maintaining the structural integrity of these tanks. The interaction between corrosive andinhibitor species in condensates/supernates on the tank wall above the liquid level, and their interactionwith vapor phase constituents as the liquid evaporates from the tank wall influences the formation ofcorrosion products and the corrosion of the carbon steel. An effort is underway to gain an understandingof the mechanism of vapor space corrosion. Localized corrosion, in the form of pitting, is of particularinterest in the vapor space. CPP testing was utilized to determine the susceptibility of the steel in asimulated vapor space environment. The tests also investigated the impact of ammonia gas in the vaporspace area on the corrosion of the steel. Vapor space coupon tests were also performed to investigate theevolution of the corrosion products during longer term exposures. These tests were also conducted atvapor space ammonia levels of 50 and 550 ppm NH{sub 3} (0.005, and 0.055 vol.%) in air. Ammonia wasshown to mitigate vapor space corrosion.

Topics

• impedance spectroscopy
• Carbon
• corrosion
• phase
• steel
• susceptibility