Evaluation on Ultrasonic Examination Methods applied to Ni-base Alloy Weld including Cracks dueto Stress Corrosion Cracking found in BWR Reactor Internal
青木 孝行 Takayuki AOKI 小林 広幸 Hiroyuki KOBAYSHI 樋口 真一 Shinichi HIGUCHI 清水 禎人 Sadato SHIMIZU
Boiling Water Reactor Ni-base Alloy Stress Corrosion Cracking TOFD Ultrasonic Examination
A Ni-base alloy weld, including cracks due to stress corrosion cracking found in the reactor internal of the oldest BWR in Japan, Tsuruga unit 1, in 1999, was examined by three (3) types of UT method. After this examination, a depth of each crack was confirmed by carrying out a little excavation with a grinder and PT examination by turns until each crack Hisappeared. Then, the depth measured by the former method was comp ared with the one measured by the latter method. n this fashion, performances of the UT methods were verified. As a result, a combination of the three types of UT method vas found to meet the acceptance criteria given by ASME Sec.XI Appendix VIII, Performance Demonstration for Jltrasonic Examination Systems- Supplement6. In this paper, the results of the UT examination described above and their evaluation are discussed.