Application of Fracture Toughness Master Curve Method for RTPTS Evaluation of Reactor Pressure Vessel

The CF value of 190.96 of was obtained from the surveillance test data of the first to the fifth for Kori-1 power plant. Using this value the RTPTS was estimated that the screening value will reach at the 27.93 EFPY before expected EOLE (End of Licence Extension). Because this value cannot satisfied the limit of EOLE for Kori-1, the precise re-assessment of integrity of RPV is needed to extend the period of operation using the advanced fracture mechanics instead of the CVN method. The master curve method studied at KNPP and BVPS-1, whose RPVs have problem of low RTPTS like Kori-1, was investigated. The RTPTS of Kori-1 RPV was anticipated using the data and concepts of the master curve method used in KNPP RPV assessment. The anticipated RTPTS at 32 EFPY is about 288 .deg. F, which is lower value than the screening temperature proposed in regulation. But, the margin to the screening temperature is not so much as expected value before investigation