Development of leak-before-break assessment method for Japan Sodium cooled Fast Reactor pipe, 1; Crack opening displacement assessment of thin wall pipes made of modified 9Cr-1Mo steel

ナトリウム冷却高速炉(JSFR)配管のLBB評価法の開発,1; 改良9Cr-1Mo鋼製薄肉管のき裂開口変位評価

若井 隆純 ; 町田 秀夫*; 荒川 学*; 吉田 伸司*; 江沼 康弘  

Wakai, Takashi; Machida, Hideo*; Arakawa, Manabu*; Yoshida, Shinji*; Enuma, Yasuhiro

ナトリウム冷却高速炉(JSFR)の改良9Cr-1Mo鋼製薄肉大口径配管に対する破断前漏えい(LBB)評価に用いるき裂開口変位評価法を開発した。この方法では、き裂開口変位を、弾性域,小規模降伏域及び大規模降伏域に分けて計算する。この方法の妥当性検証を、周方向貫通き裂を有する改良9Cr-1Mo鋼薄肉管に対する高温における4点曲げ試験によって行った。その結果、LBB評価に適用可能な適切な評価方法を提案することができた。

This was carried out to establish crack opening displacement (COD) evaluation methods used in Leak-Before-Break (LBB) assessment of sodium pipes of the Japan Sodium cooled Fast Reactor (JSFR). A COD assessment method applicable to thin walled large diameter pipe made of modified 9Cr-1Mo steel was proposed in this study. In this method, COD was calculated by classifying the components of COD; elastic, local plastic and fully plastic. In addition, the verification of this method was performed by comparing with 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. The rational leak rate evaluation method in LBB assessment was proposed.