Establishment of Bare Metal Visual Examination Guideline for Class 1 Pressure Vessels such as Reactor Pressure Vessel
名越 康人 （三菱重工） 一ノ瀬 雄平 （関西電力） 佐藤 寿志 （原子力安全推進協会）
Bare metal visual examinationBoric acid corrosionDavis-BesseGuidelinePWSCCReactor pressure vessel
Bare metal visual examination (BMV) is required for dissimilar metal welds of class 1 component for PWR (Pressurized Water Reactor) in inspection and evaluation guidelines published by Japan Nuclear Safety Institute (JANSI). However, there have been no guidelines which specify the procedures for BMV. In 2021, the guideline stipulating specific procedures for BMV were established by JANSI. This guideline includes both lessons-learned related to the boric acid corrosion on reactor pressure vessel upper head at the Davis-Besse nuclear power plant in the USA and other operational experiences with reactor coolant system leakage, which are intended to alert the examiners to the possibility of similar events occurring at domestic nuclear power plants. In this paper, the guideline for BMV established in 2021 is overviewed.