Long-term aging of light water reactor concrete containments

This paper evaluates the aging of light water reactor concrete containments and identifies three degradation mechanisms that have the potential to cause widespread aging damage after years of satisfactory experience: alkali–silica reactions; corrosion of reinforcing steel, steel liner, and prestressing steel; and sulfate attack. The aging evaluation is based on a comprehensive review of the relevant technical literature. Low-alkali cement and slow-reacting aggregates selected according to ASTM requirements cause deleterious alkali–silica reactions. Low concentrations of chloride ions can initiate corrosion of the reinforcing steel if the hydroxyl ions are sufficiently reduced by carbonation, leaching or magnesium sulfate attack. Magnesium sulfate attack on concrete can also cause loss of strength and degradation of cementitious properties of the containment concrete after long-term exposure. The techniques for inspecting, mitigating and repairing these long-term aging effects are discussed.