NUREG/CR-6706 "Capacity of Steel and Concrete Containment Vessels with Corrosion Damage" S103109

Corrosion damage has been found in a number of nuclear power plant containment structures, and this could degrade the pressure capacity of the vessel. This has prompted concerns regarding the capacity of corroded containments to withstand accident loadings. For the low-carbon, low-strength steels used in containments, the effect of corrosion on material properties is discussed in this report, and a basis for using finite element analyses to calculate the capacity of a vessel with corrosion damage is developed. The pressure capacity was calculated for two typical steel containment vessels with no corrosion damage: a PWR Ice Condenser containment and a BWR Mark I containment. The pressure capacity was also calculated for two typical concrete containment vessels with no corrosion damage: a PWR reinforced concrete sub-atmospheric containment and a PWR prestressed concrete containment vessel. Multiple analyses were then performed with the location of corrosion and the amount of corrosion varied in each analysis. A "lower bound", "best estimate", and "upper bound" failure level was predicted for each case. These limits were established by: determining the amount of variability that exists in material properties of typical containments, estimating the amount of uncertainty associated with the level of modeling detail and modeling assumptions, and estimating the stress concentration effect caused by a rough, uneven, corroded surface.