高速炉蒸気発生器伝熱管のセルフウェステージ現象解明実験,2

Experiments of self-wastage behavior due to sodium-water reaction in steam generator of sodium-cooled fast reactor, 2

下山 一仁 ; 栗原 成計 ; 菊地 晋  ; 梅田 良太 

Shimoyama, Kazuhito; Kurihara, Akikazu; Kikuchi, Shin; Umeda, Ryota

ナトリウム(Na)冷却高速炉の蒸気発生器(SG)伝熱管に生じた微細な貫通亀裂から水/蒸気がNa中に漏えいして自管が損傷するセルフウェステージ現象について、疲労き裂を模擬した微細孔型試験体を用いた高温Na中での実験を実施し、損耗形状の時間変化、損耗部での腐食環境に関するデータを取得した。第1報で報告したピンホール型の微細孔損耗挙動実験と比較した結果、セルフウェステージ率に及ぼす初期貫通欠陥形状(ピンホール, 疲労き裂)の影響は有意ではなく、疲労き裂の方が出口部の縁長が長く、貫通破損に至った時の減肉体積や開口面積は大きくなる傾向にあることが確認された。

Self-wastage comes from water/steam leak through the penetrating crack caused in the steam generator tube of sodium-cooled fast reactor. When the self-wastage proceeds to inside wall of tube, breach area and water leak rate will be larger, then, it will be likely to spread the affected area caused by sodium-water reaction. It is very important to clarify the self-wastage behavior for locally affected region and detection of the water leak in real plant. In the 1st report, the authors have performed the self-wastage experiments for the pinhole type micro crack. In this report, fatigue crack type self-wastage experiments were carried out to evaluate the effect of wastage form/geometry and water leak rate, it was confirmed that initial defect geometry, such as pinhole and fatigue crack, does not strongly influence to self-wastage rate.