ふげんを活用した軽水炉の高経年化調査研究

Studies on plant aging of light water reactors using the Fugen NPS

海老根 典也 

Ebine, Noriya

高経年化技術評価等における国の規制判断に必要な技術的知見を収集・整備に資することを目的として、約25年間運転した「ふげん」の機器・構造物の実機材料や運転データを用いて、配管の減肉状況や、SCC対策技術の有効性に関する調査を行った。配管減肉については減肉率データの収集と検討、減肉予測式との比較、配管減肉データベースを構築し、ふげんの配管減肉管理の妥当性を確認した。SCCに関しては、金属組織観察や超音波検査からその発生が無いことを確認した。さらに残留応力測定や溶接熱影響部の詳細調査結果から、SCCの発生が抑制できたものと考えられSCC対策技術の有効性を確認した。

In order to provide the technical information for the safety regulation on the aging management technical evaluation for the current commercial light water reactors (LWRs), wall thinning of the steel piping and verification of the countermeasures against SCC using the served materials of "Fugen" Power Station retired after 25 years operation have been investigated. Reliability of the wall thinning rate of the steel piping was examined referring the inspection data and the predicted calculations. Using these results, wall thinning data base was established. The validity of the management of pipe wall thinning at Fugen was examined. For SCC, there was no observed crack by metallurgical structure observations and ultrasonic inspections. It was thought that SCC was controlled judging also from the measurements of residual stress and the analysis of heat affected zone. The effectiveness of SCC management techniques at Fugen was examined.