In-service inspection program of PWR containment post-tensioning system

The in-service inspection procedure for the ungrouted post-tensioning system of the two identical PWR containment is prepared to conform to newly proposed USNRC Regulatory Guide 1.35, Rev. 3 and 1.35.1. The containment structure has a cylindrical wall and hemispherical dome with vertical inverted U-type tendons. The tendon in-service inspection program consists of visual inspection, tendon prestress monitoring, and material test of tendon strand and filler grease. Specifically, by constructing the strain influence line of each tendon rather than following the approach in the proposed Regulatory Guide, more reasonable values of concrete elastic shortening loss are reflected in the tolerance band for prestress monitoring