Thermal transient test and strength evaluation of a tubesheet structure made of Mod.9Cr-1Mo steel, 2; Creep-fatigue strength evaluation

改良9Cr-1Mo鋼製管板構造試験体の熱過渡試験と強度評価,2; クリープ疲労強度評価

安藤 勝訓 ; 長谷部 慎一; 小林 澄男; 笠原 直人*; 豊吉 晃*; 大前 隆広*; 江沼 康弘*

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

JSFRの蒸気発生器のために設計された球形管板の破損様式を明らかにするために実施された管板構造試験体のナトリウム中繰返し熱過渡強度試験の結果ついて、試験中に得られたナトリウム温度分布およびその履歴と、試験体表面温度分布およびその履歴をもとに熱伝導解析を実施し、試験体の温度分布履歴を算定した。この結果を用いて応力解析を実施し、応力発生状況とき裂発生状況の比較、破損機構の検証、強度評価結果とき裂の関係調査などを実施した。非弾性解析結果に基づく評価では2.59mmのき裂に対してファクター3で寿命を予測できた。

In this study, the strength of a tubesheet test model simulating a semispherical tubesheet structure subjected to cyclic thermal transients was evaluated using the finite element analysis (FEA). A test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loading using a large-scale sodium loop, in which elevated-temperature sodium at 600C and 250C was flowed repeatedly and kept at the final temperature for 2 and 1 h, respectively. Heat transfer analysis and stress analysis were performed using the sodium temperature data measured during the test. Then, the elastic and inelastic stress analysis results were used to investigate the failure mechanism by creep-fatigue damage and evaluate the failure strength. The evaluation based on the results of inelastic analysis estimated the number of cycles to failure within a factor of 3.