In-service inspections and R&D of PCCVs in Japan

In Japan, the following five plants in operation use prestressed concrete containment vessels (PCCVs): Tsuruga # 2 (in operation in 1987), Ohi # 3 and # 4 (in operation in 1991 and 1993. respectively), and Genkai # 3 and # 4 (in operation in 1994 and 1997, respectively). These plants have adopted the hemispherical dome type PCCV with two or three buttresses and unbonded prestressing system. For the above five PCCVs, lift-off tests in the in-service inspection have been carried out 1, 3 and 5 years after the beginning of operation. In addition, concrete strain and temperature have been measured periodically. This paper presents the in-service inspection methods and results of the lift-off tests and the measurement of concrete strain. The given results are as follows. Measured strain shows good agreement with calculated creep and shrinkage strain, so tendon tensile force can be predicted by the design method using calculated strain, and it also matches well the results of the lift-off tests.