Development of LBB assessment method for Japan Sodium Cooled Fast Reactor (JSFR) pipes, 4; Verification of crack opening displacement assessment method for thin wall pipes made of Mod.9Cr-1Mo steel

JSFR配管LBB評価法の開発,4; 改良9Cr-1Mo鋼製薄肉配管のき裂開口変位評価法の検証

若井 隆純 ; 町田 秀夫*; 吉田 伸司*; 川島 芙美子*; 菊地 浩一*; Xu, Y.*; 月森 和之

Wakai, Takashi; Machida, Hideo*; Yoshida, Shinji*; Kawashima, Fumiko*; Kikuchi, Koichi*; Xu, Y.*; Tsukimori, Kazuyuki

き裂開口変位評価法の改良と改良9Cr-1Mo鋼製薄肉管の高温4点曲げ破壊試験結果による妥当性検証について述べる。溶接継手を有しない管のき裂開口変位評価結果は、実験結果とよく一致したが、き裂が溶接金属又は溶接熱影響部にある場合には、き裂開口変位は過大評価された。この結果を踏まえ、LBB評価に適用する合理的な漏えい評価法が提案された。

This paper describes the improved COD assessment method and verifies the validity of the method based on the results of a series of four-point bending tests at elevated temperature using thin wall modified 9Cr-1Mo steel pipe containing a circumferential through wall crack. As a result, COD values calculated by the proposed method were in a good agreement with the experimental results for the uniform pipe without weld. In the case that the crack was machined at weld metal or heat affected zone (HAZ), proposed method predicted relatively larger COD than the experimental results. The causes of such discrepancies were discussed comparing with the results of finite element analyses. Based on these examinations, the rational leak rate evaluation method in LBB assessment was proposed.